Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/03/07

.SYNOPSIS...A DEEP MARINE LAYER WILL CAUSE VARIABLE CLOUDINESS WEST OF THE MOUNTAINS THROUGH FRIDAY MORNING WITH A FEW SPRINKLES THIS EVENING. OTHERWISE...FAIR AND A LITTLE WARMER FRIDAY. MOSTLY CLEAR AND MUCH WARMER THIS WEEKEND THROUGH EARLY NEXT WEEK UNDER HIGH PRESSURE. UPPER LEVEL LOW PRESSURE WILL BRING MORE CLOUDS AND COOLING TOWARD THE MIDDLE OF NEXT WEEK.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

.SHORT TERM (TODAY-SUN)...THERE WAS A DEEP MOIST LAYER WITH PARTLY TO MOSTLY CLOUDY SKIES WITH A FEW LIGHT SHOWERS OVER AND W OF THE MOUNTAINS TODAY. ACARS SOUNDINGS INDICATED AN INVERSION BASED NEAR 6000 FT WITH STRONG NW WINDS ALOFT. ONSHORE GRADIENTS WITH ABOUT 4 MB SAN-IPL.

RESIDUAL MOISTURE AND A DEVELOPING DEEP MARINE LAYER WILL CAUSE LOW CLOUDS AND PATCHY FOG W OF THE MOUNTAINS TONIGHT AND FRI MORNING. THERE COULD STILL BE A FEW SPRINKLES OR LIGHT SHOWERS FROM THE W OF THE MOUNTAIN RIDGES THIS EVENING. GOOD CLEARING FRI AFTERNOON AS OFFSHORE FLOW BEGINS TO DEVELOP. A LITTLE WARMER FRI. DRY NW FLOW ALOFT THROUGH FRI WITH A HIGH AMPLITUDE RIDGE OFF THE W COAST. THIS RIDGE WILL SLOWLY SHIFTS E SAT AND SUN AND OFFSHORE GRADIENTS CONTINUE. THIS WILL BRING MOSTLY CLEAR SKIES AND MUCH WARMER DAYS...ESPECIALLY SUN. LOCALLY BREEZY IN THE MOUNTAINS AND DESERTS TODAY DUE TO ONSHORE FLOW AND WINDS ALOFT...THEN LOCAL GUSTY OFFSHORE WINDS FRI THROUGH SUN. MOST WINDS SHOULD REMAIN BELOW ADVISORY STRENGTH BUT THERE COULD BE LOCAL STRONGER GUSTS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES...ESPECIALLY BELOW THE CAJON PASS AND IN THE SANTA ANA MOUNTAINS. LARGE W SWELL WILL CAUSE ABOVE NORMAL SURF THROUGH SAT MORNING.

&&

.LONG TERM (MON-THU)...CONTINUED MOSTLY CLEAR AND WARM MON WITH HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW. SLIGHTLY COOLER IN MOST AREAS TUE AS THE HIGH WEAKENS. A PAC TROUGH WILL APPROACH THE W COAST WED AND MOVE THROUGH THU FOR MORE CLOUDS AND COOLING. MODELS HAVE BEEN INCONSISTENT ON THE STRENGTH OF THIS TROUGH AND CANNOT COMPLETELY RULE OUT THE POSSIBILITY OF PRECIP THU.

&&

.AVIATION... A DEEP MARINE LAYER WILL CONTINUE THROUGH TONIGHT KEEPING LAYERS OF STRATOCU OVER MOST OF THE AREA FROM THE MOUNTAINS TO THE COASTAL WATERS. THE LOWEST SCATTERED TO BROKEN LAYER SHOULD BE AROUND 3000 FEET MSL WITH ADDITIONAL LAYERS AROUND 4500 FEET AND 6000 FEET MSL. TOPS SHOULD BE AROUND 7000 FEET. THE MARINE LAYER SHOULD BEGIN TO LOWER FRIDAY MORNING WITH BETTER CLEARING EXPECTED BY FRIDAY AFTERNOON.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

HIGH SURF ADVISORY UNTIL 2 AM PST SATURDAY FOR SAN DIEGO COUNTY COASTAL AREAS. SEE LAXCFWSGX.

&&

$$

PUBLIC...DVA AVIATION...HORTON

.MESOSCALE UPDATE... SO FAR EVERYTHING SEEMS TO BE GOING ACCORDING TO PLAN...AS LEADING EDGE OF PRECIPITATION SHIELD IS WORKING INTO SE NY AT THIS TIME.

SURFACE ANALYSIS SHOWS VERY WEAK GRADIENT IN PLACE WITH LITTLE IF ANY LOW LEVEL TEMPERATURE ADVECTION. TEMPERATURES ARE WARM ENOUGH FOR RAIN ON LONG ISLAND AND IMMEDIATE NYC AREA...WHILE DECENT SNOWS ARE MOVING THROUGH NE PA AND INTERIOR SE NY. THIS AREA OF SNOWFALL IS TAKING AIM ON OUR WESTERN/CENTRAL MA AND SW NH ZONES...PROBABLY EXTREME N CENTRAL CT AS WELL. FARTHER S AND E...TEMPERATURES ARE MARGINAL FOR SNOW AT START AND WE WILL EITHER SEE RAIN OR A RAIN/SNOW MIX ONTO COASTAL PLAIN...BEFORE DYNAMIC COOLING COMES INTO PLAY WITH STEADIER PRECIPITATION AND FORCES A CHANGE TO SNOW.

WE HAVE REVIEWED 18Z MODELS AND THEY LARGELY SUPPORT GOING FORECAST... NAM REMAINS COLDER AND SHOWS BEST SNOWGROWTH POTENTIAL ALONG MASS PIKE WHILE GFS IS A BIT WARMER. RECENT AIRCRAFT OBSERVATION FROM KBOS REPORTED 925 MB TEMPERATURE OF 0C WHILE 18Z NAM SHOWED -2C...SO RIGHT OFF BAT NAM IS TOO WARM...AT LEAST ON COASTAL PLAIN. 18Z GFS HAS 0C AT 00Z SAT AND LOOKS BETTER.

AS A RESULT...WE THINK FORECAST IS IN GOOD SHAPE WITH MAX 2-4 INCHES IN SW NH. OPTION REMAINS ON TABLE FOR UPPING TOTALS IN NORTHERN MA INTO 2-4 INCH RANGE...BUT RIGHT NOW WE STILL ARE NOT CONFIDENT THAT ANY 4 INCH TOTALS IN NORTHERN MA WOULD BE LOCALIZED.

JWD

&&

.PREV DISCUSSION... /ISSUED 421 PM EST FRI FEB 2 2007/

..POTENT BUT FAST MOVING SYSTEM WILL BRING LIGHT ACCUMULATING SNOWS EARLY TONIGHT TO INTERIOR SOUTHERN NEW ENGLAND - POTENTIALLY THE MOST WIDESPREAD EVENT OF THIS WINTER SEASON...

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... 12Z NAM/GFS ARE IN GOOD AGREEMENT SHOWING POTENTIAL FOR LIGHT ACCUMULATING SNOWS IN MUCH OF SOUTHERN NEW ENGLAND TONIGHT...MAINLY BEFORE MIDNIGHT AS A POTENT SHORT WAVE AND ITS SURFACE COLD FRONT MOVE THROUGH REGION.

CROSS SECTIONS ON BOTH MODELS SHOW A PERIOD OF STRONG MID LEVEL FORCING MOVING THROUGH REGION BETWEEN 00Z AND 06Z...ESPECIALLY NW OF A LINE FROM HARTFORD TO WORCESTER AND BOSTON. LIMITING FACTORS FOR DECENT SNOW ACCUMULATIONS ARE SPEED OF SYSTEM AND A LACK OF GOOD MID LEVEL FRONTOGENESIS...BUT IN THIS CASE DYNAMICS SHOULD BE STRONG ENOUGH TO OVERCOME THAT CONCERN. THIS LOOKS TO BE A CASE WHERE IT COULD SNOW HARD FOR A COUPLE OF HOURS FROM WESTERN/CENTRAL MA INTO SW NH.

MAX SNOW GROWTH ZONE IS NOT TOO FAR OFF ON BOTH MODELS...ALTHOUGH GFS IS A BIT WARMER. NAM HAS IT ROUGHLY ALONG ROUTE 2 AND MASS PIKE CORRIDORS...AND GFS A BIT FARTHER N FROM ROUTE 2 INTO SW NH. THIS IS PRIMARILY DUE TO LOW LEVEL WARMING AS WE NOTED RAIN/SNOW LINE ON NAM IS FARTHER S...FROM MARTHAS VINEYARD TO HYANNIS EARLY THIS EVENING...WHILE GFS IS WARMER AND TAKES IT UP INTO PROVIDENCE TO BOSTON CORRIDOR. RIGHT NOW WE ARE LEANING TOWARD COLDER SOLUTION...GIVEN DYNAMIC COOLING SHOULD BE MORE THAN ABLE TO OFFSET ANY RESIDUAL LOW LEVEL WARMING...BUT THAT DOES NOT RULE OUT RAIN OR MIXED RAIN/SNOW AT START AS FAR NW AS PROVIDENCE AND BOSTON.

FOR WHAT ITS WORTH WE TOOK A QUICK LOOK AT 1000 TO 850 MB THICKNESSES AND NAM IS DOING A BETTER JOB RIGHT NOW THAN GFS.

REGIONAL RADAR MOSAIC SHOWS LARGE AREA OF SNOW ADVANCING NE FROM NY/PA AND LEADING EDGE IS HANDLED WELL BY BOTH NAM/GFS. WE EXPECT TO SEE THIS AREA BLOSSOM FURTHER AS IT APPROACHES NEW ENGLAND DUE TO INCREASING WARM ADVECTION...SO THIS MAY NOT BE A CASE WHERE WE CAN EXTRAPOLATE LEADING EDGE FOR TIMING OF ONSET. WE THINK IT WILL START IN CT VALLEY AROUND 5 OR 6 PM...THEN IN RI/EASTERN MA AROUND 7 OR 8 PM...POSSIBLY AS LATE AS 8-9 PM ON CAPE COD.

QPF SHOULD AVERAGE 0.10 TO 0.25 INCH OVER REGION WITH HIGHEST AMOUNTS IN NORTHERN MA AND SW NH. TEMPERATURE PROFILES SUGGEST WE GO HIGHER THAN STANDARD 10:1 RATIO...PERHAPS AS MUCH AS 15 OR 20:1. THIS YIELDS SNOWFALL TOTALS OF 2 TO 4 INCHES IN SW NH...PERHAPS AS MUCH AS 5 INCHES IN A FEW LOCATIONS IN NORTHERN CHESHIRE AND NORTHERN HILLSBOROUGH COUNTIES. TOTALS OF 1 TO 3 INCHES ARE EXPECTED DOWN INTO NORTHERN CT...NORTHERN RI AND I-95 BETWEEN PROVIDENCE AND BOSTON. A DUSTING TO PERHAPS AN INCH CAN BE EXPECTED IN CENTRAL RI AND MUCH OF SE MA...WITH LITTLE OR NO ACCUMULATION ON S COAST...CAPE COD AND ISLANDS.

THESE AMOUNTS DO NOT REQUIRE US TO ISSUE ANY ADVISORIES...SINCE WE NEED 3 TO 5 INCH TOTALS ON AVERAGE FOR NH. IT IT STILL POSSIBLE THAT PORTIONS OF ROUTE 2 CORRIDOR INTO INTERIOR NE MA GET 2 TO 4 INCH AMOUNTS...BUT WE ARE NOT CONFIDENT ENOUGH TO GO THAT HIGH. A SOLID 1 TO 3 INCHES IS MUCH MORE LIKELY THERE RIGHT NOW.

ONCE COLD FRONT CROSSES REGION AFTER MIDNIGHT...WE GET INTO A STRONG COLD ADVECTION PATTERN AS 850 MB TEMPERATURES DROP AND INCREASING W FLOW ENSUES. WINDS WILL APPROACH ADVISORY CRITERIA SAT ON COASTAL PLAIN...MORE DUE TO SUSTAINED WIND THAN GUSTS...SO THIS WILL NEED TO BE CONSIDERED IN LATER FORECASTS. WE DECIDED TO HOLD OFF SINCE THERE IS ONLY A 1 TO 3 HOUR WINDOW SAT MORNING WHERE THIS LOOKS MOST LIKELY...BEFORE WINDS DROP OFF A BIT SAT AFTERNOON.

GOOD DRYING TAKES HOLD BEHIND FRONT AS WELL...THOUGH WITH STRONG W FLOW WE ALWAYS HAVE TO CONSIDER POSSIBLE CONTRIBUTION FROM LAKE EFFECT OFF LAKE ONTARIO WHICH CAN BE TRANSPORTED OVER BERKSHIRES AND INTO WORCESTER HILLS/MERRIMACK VALLEY. WE THINK THERE WILL BE TOO MUCH SUBSIDENCE AND DRYING FOR THIS TO TAKE PLACE...ESPECIALLY WITH ANTICYCLONIC FLOW AT LOWER LEVELS. FLOW ALSO HAS TOO MUCH OF A W COMPONENT TO BRING ANY OCEAN EFFECT TO CAPE COD... ANYTHING WILL BE FOCUSED OFFSHORE.

ANOTHER COLD FRONT IS EXPECTED TO PUSH THROUGH NEW ENGLAND SAT NIGHT. ALTHOUGH MOISTURE IS LIMITED...THERE DOES APPEAR TO BE ENOUGH TO GENERATE SOME FLURRIES WITH ITS PASSAGE. IN ADDITION...AS FLOW BACKS TO SW AHEAD OF FRONT...THERE MAY BE ENOUGH INSTABILITY ON S COAST TO GENERATE OCEAN EFFECT SNOW SHOWERS...MAINLY FOR VINEYARD...NANTUCKET AND MID CAPE. WE INCLUDED SLIGHT CHANCE POPS THERE FOR NOW.

LONG TERM /SUNDAY THROUGH FRIDAY/... TRICKY TEMPERATURE FORECAST DURING THIS STRETCH OF TIME. ANOTHER ARCTIC FRONT IS EXPECTED TO APPROACH THE MA/NH BORDER SUNDAY NIGHT INTO MONDAY. THERE IS SOME QUESTION AS TO WHEN THE REALLY COLD AIR ARRIVES...CONFIDENCE IS HIGHEST FOR MONDAY NIGHT INTO TUESDAY. WITH THE MODELS IN DECENT AGREEMENT...USED THE CONSENSUS AS THE BASIS FOR THIS FORECAST.

02/12Z GFS ENSEMBLES IN LINE WITH THE OPERATIONAL RUNS IN ADVERTIZING A PROLONGED COLD COLD SNAP FOR MUCH OF NEXT WEEK. HAVE GENERALLY STAYED BELOW THE MOS GUIDANCE TO VARYING DEGREES FOR ALL OF NEXT WEEK. WINDS THIS TIME ARE EXPECTED TO BE MORE FROM THE WEST THAN THE NORTHWEST...WHICH WOULD LEAD TO BETTER DOWNSLOPING ACROSS EASTERN MA.

PRECIPITATION WISE...NOT MUCH GOING ON. SEVERAL WEAK MOISTURE-STARVED TROUGHS SHOULD ROTATE ACROSS SOUTHERN NEW ENGLAND AT TIMES NEXT WEEK. ONLY EXPECTING CLOUDS FOR THE MOST PART...BUT THERE IS A SMALL POSSIBILITY OF SNOW SHOWERS DURING THE MIDDLE OF NEXT WEEK. NO SYSTEMS OF CONSEQUENCE SEEN ON THE HORIZON.

AVIATION /21Z-18Z/... LITTLE CHANGE IS EXPECTED THROUGH EARLY THIS EVENING...WITH PREDOMINATELY MVFR CEILINGS...THOUGH AREAS OF IFR WILL HANG TOUGH NEAR CAPE COD WHILE VFR CEILINGS PREVAIL IN NW MA.

SNOW SHOWERS WILL REACH WESTERN TERMINALS 22-24Z AND COASTAL PLAIN 00Z-02Z...ALTHOUGH IT WILL BE WARM ENOUGH FOR A RAIN/SNOW MIX IN KBOS/KPVD TERMINALS AND ALL RAIN KHYA/KACK. LOWEST CONDITIONS EXPECTED TO IMPACT INTERIOR...FROM KORH TO KMHT WHERE LIFR IS POSSIBLE FOR A TIME PRIOR TO 06Z. OTHERWISE WIDESPREAD MVFR CONDITIONS ARE FORECAST WITH AREAS OF IFR.

RAPID IMPROVEMENT WILL TAKE PLACE 07Z-09Z AS COLD FRONT MOVES THROUGH AND BRINGS INCREASING W WINDS. COASTAL TERMINALS WILL GUST TO 25KT RIGHT AFTER FRONTAL PASSAGE AND THEN POTENTIALLY GUST TO 30-35KT SAT. INLAND TERMINALS WILL GUST TO 25KT STARTING AROUND 12Z SAT. MECHANICAL TURBULENCE IS LIKELY TO BECOME A FACTOR STARTING AROUND DAYBREAK.

MARINE... GALE WARNINGS ARE BEING ISSUED FOR OUTER WATERS...AS WE EXPECT W WINDS TO REACH GALE FORCE TOWARD DAYBREAK SAT. ALTHOUGH WINDS MAY DIMINISH A BIT DURING DAY...ANOTHER ROUND OF W GALES IS EXPECTED SAT NIGHT BEHIND NEXT COLD FRONT...SO FOR SIMPLICITY WE EXTENDED GALE WARNINGS INTO SAT NIGHT.

SIMILARLY...SMALL CRAFT ADVISORIES ARE BEING ISSUED FOR REMAINDER OF WATERS BEGINNING LATE TONIGHT AND LASTING THROUGH SAT NIGHT. CONFIDENCE ON REACHING GALES IS SOMEWHAT LESS SINCE IT IS MORE MARGINAL CLOSER TO SHORE...BUT THERE REMAINS POSSIBILITY THAT LATER FORECASTS WILL UPGRADE SOME OF THESE WATERS AS WELL.

IN ADDITION TO WIND...FREEZING SPRAY IS EXPECTED AROUND DAYBREAK SAT MAINLY NEAR SHORE...THEN AGAIN LATE SAT NIGHT OVER MUCH OF COASTAL WATERS.

A PROLONGED PERIOD OF GALE FORCE WINDS POSSIBLE FROM SUNDAY INTO MONDAY NIGHT. ANOTHER SURGE OF ARCTIC AIR WILL ALSO PRESENT THE POSSIBILITY OF FREEZING SPRAY FOR MOST OF NEXT WEEK AS WELL. PERSISTENT WEST WINDS WILL LEAD TO ROUGH SEAS ACROSS THE SOUTH COASTAL WATERS AND OUTER EAST COASTAL WATERS FOR MOST OF THE WEEK AS WELL.

&&

.BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM SATURDAY TO 6 AM EST SUNDAY FOR ANZ230>237.

GALE WARNING FROM 4 AM SATURDAY TO 6 AM EST SUNDAY FOR ANZ250- 254-255.

&&

$$

.UPDATE...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS OVER THE LAST SEVERAL HOURS SHOWED SW 1000-850MB FLOW YESTERDAY MORNING GOT REINFORCED BY A PASSING AND MOISTURE-STARVED SHORTWAVE ALOFT. THE SHORTWAVE ITSELF PRODUCED MINIMAL SNOWFALL...LESS THAN AN INCH. DAYTIME HEATING/DIURNAL DISRUPTION DID A NUMBER ON THE BANDING...WITH MORE CELLULAR ACTIVITY SEEN FROM AFTERNOON INTO SUNDOWN. WITH THE LOSS OF HEATING...THE DIURNAL SNOW SHOWERS DECREASED SUBSTANTIALLY...AND THE SKIES CLEARED FROM ROUGHLY US 131 EASTWARD. AS THE EVENING HAS PROGRESSED...PURE LES HAS BEEN RE-ESTABLISHING ITSELF. CLOUDS ARE BEGINNING TO SPREAD BACK TO THE EAST AND THE LES HAS INCREASED A TOUCH...WHILE SHOWING MORE ORGANIZED BANDING. THIS HAS BEEN HELPED SOMEWHAT BY AN INCREASE IN MID LEVEL MOISTURE AHEAD OF MAIN/NEXT SHORTWAVE SEEN WORKING INTO WESTERN IOWA. THE EXTENT OF THE HELP IS TOUGH TO DISCERN AS THERE ARE NOT MANY TAMDAR SOUNDINGS TO SAMPLE THIS EVENING. HOWEVER...ONE SUCH SOUNDING DOES SUGGEST THAT A DRY LAYER REMAINS BETWEEN 650-825MB...SO LES INCREASING IS MORE LIKELY JUST A FUNCTION OF RE-ORGANIZATION AFTER LOSS OF HEATING.

WINDS HAVE DIED OFF MOST AREAS...THE EXCEPTIONS BEING ALONG THE LAKE MICHIGAN LAKESHORE AND AT TIMES ON THE HIGHER TERRAIN OF INTERIOR NRN LOWER. THIS HAS LIMITED THE BLOWING AND DRIFTING FOR MOST. TEMPERATURES HAVE DROPPED INTO THE ZERO TO +12F RANGE...WARMEST ALONG THE LAKESHORES. THE LAKE EFFECT SNOWS HAVE ORIENTED TO A 250 WSW DIRECTION IN NRN LOWER...WHILE A 280 FLOW HAS HUNG ON ACROSS CHIPPEWA COUNTY. THIS SUGGESTS THAT TROUGHING STILL LINGERS AROUND THE STRAITS REGION. ONLY WHITEFISH POINT HAS BEEN SEEING SNOW SHOWERS IN EASTERN UPPER...WHILE MANY OF THESE INTERIOR LOCALES HAVE CLEARED OUT. IN NRN LOWER...THE WSW FLOW HAS RESULTED IN EMMET/CHARLEVOIX AND CHEBOYGAN ONCE AGAIN BEING THE TARGET OF THE MAIN SNOW SHOWERS. ANTRIM/OTSEGO TO A LESSER DEGREE. SNOWFLAKES HAVE BEEN QUITE SMALL WITH COLD H8 TEMPS DROPPING INTO THE -20C RANGE. SNOW REPORTS FROM TODAY HAVE SHOWN 4-5 INCHES AS THE HIGH NUMBER IN NRN LOWER (EMMET/CHEBOYGAN)...WITH PARADISE COMING IN WITH 7 INCHES (WHITEFISH POINT 2INCHES...TO SHOW HOW THESE SNOWS CAN VARY).

WITH ALL THAT SAID...ABSENCE OF SNOW SHOWERS IN WSW FLOW OVERNIGHT IN EASTERN UPPER...OUTSIDE OF CEDARVILLE AND DRUMMOND ISLAND...HAVE ENDED THE ADVISORIES. THESE WILL MORE THAN LIKELY HAVE TO BE PICKED UP AGAIN IN AT LEAST CHIPPEWA COUNTY FOR TOMORROW AFTERNOON AS WINDS SHIFT BACK AROUND TO NW WITH DEEP MOISTURE AND LONGER FETCH/STRONG AND GUSTY WINDS. TOO LONG OF TIME FOR THERE TO BE LITTLE TO NO ACTION TO KEEP THE HEADLINE GOING.

IN NRN LOWER...HAVE KEPT ALL ADVISORIES...EVEN THOUGH THERE IS A LULL IN THE ACTION RIGHT NOW...AND GUSTY WINDS NOT AS WIDESPREAD AS IT WAS IN THE AFTERNOON. THE SNOWFALL WILL INCREASE IN INTENSITY LATE TONIGHT AND TOMORROW MORNING...AS AFOREMENTIONED NEXT SHORTWAVE TROUGH WORKS INTO SRN LOWER. MOST OF THE STRONGER -DIVQ WILL RESIDE IN SRN LOWER...BUT COULD CLIP AREAS SOUTH OF GTV BAY TO ALLOW FOR A BETTER INCREASE IN INTENSITY.

HAVE CUT SNOW AMOUNTS BACK FOR THE OVERNIGHT...AS FLAKES WILL BE TOO SMALL IN THE COLD AIR MASS...AND ANY FORCING ALOFT WILL RESIDE MAINLY TO OUR SOUTH. AM LOOKING FOR UP TO 1.5 INCHES THROUGH THE ENTIRE EVENING...WITH MAYBE 2 OT 2.5 OVERNIGHT. TOTALS MOST AREAS WILL BE IN THE 1-3 INCH RANGE IN SW FLOW REGIMES. SOME BLOWING AND DRIFTING...BUT THIS WILL BE MORE WIDESPREAD TOMORROW AS MIXING OVER LAND BEGINS. GUSTS TO 30 MPH WILL BE COMMON AND THE ARRIVAL OF THE SHORTWAVE WILL HELP THE GUSTS...AS WELL AS ENHANCE/INCREASE THE INTENSITY OF THE SNOW SHOWERS TO PROVIDE A PERIOD OF NASTY WINTER WEATHER CONDITIONS. SIGNIFICANTLY REDUCED VISIBILITIES WITH BLOWING AND DRIFTING SNOW ARE EXPECTED AT TIMES TOMORROW...WITH INTERMITTENT PEEKS AT BLUE SKY. MOST EVERYONE WILL SEE SNOW TOO...AS CONVECTIVE SNOW SHOWERS LOOK TO DEVELOP IN THE DEEP MOIST MIXED LAYER. SNOW AMOUNTS TOMORROW...MAYBE ANOTHER 1 TO 3...FOR A TOTAL OF NO MORE THAN 6 INCHES IN ANY ONE AREA. THIS SCENARIO LEADS TO THE CONTINUANCE OF WINTER STORM WARNINGS...JUST EXPECT THIS TO BE WORST TOMORROW...RATHER THAN TONIGHT (EXCEPT FOR THOSE AREAS RIGHT ALONG THE LAKE WHERE GUSTS WILL BE MORE COMMON). SMD

&&

.PREV DISCUSSION ISSUED AT 333 PM EST FRI FEB 2 2007 DISCUSSION...SURFACE LOW HAS REACHED SE ONTARIO LATE THIS AFTERNOON. LARGE AREA OF DPVA AN ENHANCED MID/UPPER LEVEL MOISTURE HAS SPREAD INTO OUR ENTIRE CWA DRIVEN BY A STRONG SHORT WAVE ALONG THE 500 MB TROUGH. ORGANIZED W/SW FLOW LAKE BANDS OF LATE MORNING/ EARLY AFTERNOON HAS TRANSITIONED INTO A NEARLY STRAIGHT WESTERLY FLOW LAKE ENHANCED EVENT WITH LAKE BANDS SOMEWHAT EMBEDDED WITHIN WIDESPREAD SYNOPTICALLY-DRIVEN SNOW SHOWERS. MOST INTENSE BANDS CONTINUE TO TARGET FAR NRN LOWER MICHIGAN...SPECIFICALLY EMMET... CHEBOYGAN AND CHARLEVOIX COUNTIES...ALTHOUGH SURFACE OBS ALONG THE MAINLY LAKE MICHIGAN SHORELINE OF NW LOWER MICHIGAN INDICATE FAIRLY LOW VSBYS (AOB 1 SM) IN MODERATE SNOW SHOWERS. FORECAST FOR THE NEXT 24 HOURS WILL FOCUS ON THE EVOLUTION OF THIS WESTERLY FLOW LAKE ENHANCED EVENT AS ANOTHER POTENT SHORT WAVE DRIVES THRU NRN MICHIGAN OVERNIGHT AND SATURDAY MORNING. COLD...SNOW AND WIND WILL REMAIN THE PRIMARY FORECAST ISSUES THRU THE WEEKEND AND THE FIRST HALF OF NEXT WEEK.

TONIGHT AND SATURDAY...SHARP TROUGHING WILL REMAIN JUST NORTH OF ERN UPR MICHIGAN UNTIL LATE SATURDAY AFTERNOON...HELPING TO MAINTAIN NEARLY STRAIGHT WESTERLY FLOW ACROSS OUR CWA TONIGHT AND MOST OF SATURDAY. OVER-LAKE INSTABILITY WILL REMAIN EXCEPTIONAL...WITH DELTA T`S RISING INTO THE MID 20S BY LATE TONIGHT IN ONGOING CAA. INVERSION HEIGHTS WILL STAY CLOSE TO 10 KFT THIS EVENING AND THEN RISE EVEN FURTHER OVERNIGHT AS ANOTHER STRONG SHORT WAVE RIDES THRU NRN MICHIGAN. 850-700 MB RH HOLDS AROUND 90 PCT THRU THE ENTIRE TIME. OBVIOUSLY PARAMETERS WILL REMAIN VERY FAVORABLE FOR THE GENERATION OF SIGNIFICANT LAKE EFFECT SNOW SHOWERS WILL SOME SYNOPTIC ENHANCEMENT ALSO AVAILABLE...ESPECIALLY LATE TONIGHT AND SATURDAY MORNING. EXPECT 2 TO 5 INCHES OF ADDITIONAL SNOWFALL FOR THE WARNED AREAS TONIGHT AND ANOTHER 2 TO 5 INCHES ON SATURDAY. EXPECT 2 TO 3 INCHES FOR ERN UPR MICHIGAN AND FOR KALKASKA AND WEXFORD COUNTIES FOR EACH PERIOD AS WELL. ADDED HAZARDS WILL BE WIND SPEEDS GUSTING TO 25 MPH...CAUSING CONSIDERABLE BLOWING/DRIFTING SNOW AND DROPPING TEMPS COMBINING WITH THE INCREASING WIND SPEEDS TO DROP WIND CHILL READINGS INTO THE NEGATIVE TEENS. IN LIGHT OF THE MULTIPLE HAZARDS SITUATION THAT IS DEVELOPING...WILL NEED TO TRANSITION FROM LAKE EFFECT HEADLINES TO WINTER STORM WARNING/WINTER WEATHER ADVISORY HEADLINES FOR BETTER REPRESENTATION.

LATER PERIODS...THE MAIN HIGHLIGHT THROUGH NEXT FRIDAY WILL BE THE BITTERLY COLD AIR THROUGH EARLY NEXT WEEK...BEFORE WE SLOWLY WARM UP CLOSE TO AVERAGE BY THE END OF NEXT WEEK. NAM/GFS HAS BECOME IN BETTER AGREEMENT WITH THE THERMAL PROFILE AS THE CORE OF THE ARCTIC AIRMASS SPREADS OVER THE GREAT LAKES SATURDAY NIGHT INTO MONDAY. THEREAFTER...MODELS START TO DIVERGE ON TUESDAY WITH TIMING OF THE NEXT SHORTWAVE ON WEDNESDAY...BUT REMAIN IN DECENT AGREEMENT IN GENERAL WITH THE OVERALL UPPER AIR FLOW PATTERN AND THE RESULTANT RETREAT OF THE ARCTIC AIR.

SATURDAY NIGHT THROUGH SUNDAY...CORE OF THE ARCTIC AIRMASS MOVES EAST IN CONJUNCTION WITH THE MOVEMENT OF THE POLAR VORTEX ACROSS CENTRAL ONTARIO. MODELS CONTINUE TO DEPICT THE STRONGEST FORCING WILL BE ALONG A LAKE AGGREGATE TROUGH THAT SETS UP FROM NORTHERN LAKE HURON TO CENTRAL LAKE SUPERIOR DURING THE EVENING AND GRADUALLY WORKS ITS WAY TO THE SOUTH SHORE OF LAKE SUPERIOR BY SUNDAY MORNING. THE LOCATION AND MOVEMENT OF THIS FEATURE WILL LARGELY DETERMINE THE WIND DIRECTIONS...AND THEREFORE...WHO GETS THE MOST SNOW. TO THE SOUTH OF THIS TROUGH...WINDS SEEM TO BE LOCKED IN FROM THE WNW DIRECTION...AND FROM THE NW NORTH OF THE TROUGH. IN ADDITION...ABUNDANT MOISTURE WILL BE PRESENT IN THE 900-700MB LAYER ALONG WITH INVERSION HEIGHTS BETWEEN 6.5KFT AND 8KFT. THE LIMITING FACTOR...HOWEVER...WILL BE THE COLD TEMPERATURES...WHICH WILL LIMIT THE SIZE OF SNOWFLAKES AND POTENTIAL ACCUMULATIONS. NAM/GFS HAVE COME INTO BETTER AGREEMENT RECENTLY WITH THE THERMAL PROFILE...WITH TEMPS AT 850MB QUICKLY COOLING IN THE -27C TO -29C RANGE. WILL REMAIN CONSERVATIVE WITH SNOWFALL ACCUMULATIONS BETWEEN 2 AND 3 INCHES ACROSS THE SNOWBELT OF NORTHERN LOWER AND AROUND WHITEFISH POINT PER 12HR PERIOD. LOW TEMPERATURES ACROSS THE ENTIRE AREA WILL FALL BELOW ZERO AND POTENTIALLY BETWEEN -10F AND -20F AT TYPICAL COLD SPOTS. HIGHS ON SUNDAY WILL RANGE BETWEEN 2 BELOW ACROSS THE INTERIOR OF NORTHERN LOWER TO ABOUT 5 ABOVE NEAR THE LAKESHORES. WIND CHILL READINGS COULD REACH IN THE -20F TO -30F...WHICH COULD WARRANT HEADLINES COMBINED WITH OTHER FACTORS LIKE SNOWFALL. HAVE CONSIDERED HEADLINES ACROSS EASTERN UPPER WHERE THEY ARE HEADLINE FREE...BUT WILL LEAVE ALONE FOR NOW WITH THE MARGINAL SNOWFALL AND WINDCHILLS EXPECTED.

SUNDAY NIGHT AND MONDAY...NEXT SHORTWAVE ROUNDING THE POLAR VORTEX DUE TO ARRIVE DURING THE EVENING HOURS. GFS IS SLIGHTLY FASTER THAN THE OTHER MODELS(NAM/UKMET/ECMWF/CANADIAN)...SO WILL TEND TO SIDE ON THE SLOWER TIMING. BECAUSE OF THIS FORCING...LAKE EFFECT PARAMETERS LOOKING GOOD TO START THE NIGHT...WITH PLENTY OF 900-700MB RH AND INVERSION HEIGHTS ABOUT 6KFT. HOWEVER...WINDS SHIFTING FROM WNW TO NW BEHIND THE WAVE AND MORESO THE COLD 850MB TEMPS AROUND -26C WILL LIMIT SNOW ACCUMULATIONS. HEIGHTS REBOUND BEHIND THE DEPARTING WAVE WITH MID-LEVEL DRYING OCCURRING AND INVERSION HEIGHTS LOWERING TO ABOUT 4KFT BY 00Z TUE. BUT LARGE DELTA T`S AROUND 25C SHOULD HELP TO OVERCOME THE INCREASING HOSTILE ENVIRONMENT TO PROMOTE NUMEROUS SNOW SHOWERS WITHIN THE WNW-NW SNOW BELTS. ANOTHER BITTERLY COLD DAY ON TAP WITH LOWS RANGING FROM MINUS 5F NEAR THE LAKESHORES TO MINUS 15F AT THE COLD SPOTS. HIGHS WILL NOT WARM UP MUCH EITHER BUT SHOULD GET ABOVE ZERO.

TUESDAY THROUGH FRIDAY...MEDIUM RANGE MODELS AND ENSEMBLES CONTINUE TO SHOW A PATTERN DE-AMPLIFICATION TREND THROUGH THE PERIOD. SHARP WESTERN NOAM RIDGE BROADENS OUT ACROSS ALASKA AND NORTHERN CANADA WHILE THE STRONG POLAR VORTEX RETREATS NE ACROSS QUEBEC AND NEWFOUNDLAND. THIS ALLOWS THE CORE OF THE ARCTIC AIRMASS TO ALSO RETREAT NORTH...BUT KEEPS THE GREAT LAKES IN A GENERALLY BROAD WNW FLOW WITH TEMPERATURES PLENTY COLD TO SUPPORT LAKE EFFECT SNOW SHOWERS. LAST SHORTWAVE ROUNDING THE POLAR VORTEX LOOKS TO ARRIVE AROUND THE WEDNESDAY TIMEFRAME...BUT THIS SEEMS TO BE THE ONLY REASONABLE SYSTEM TO CONTEND WITH OUTSIDE OF THE LAKE EFFECT REGIMES. AFTER A COLD START TO THE PERIOD...TEMPERATURES LOOK TO REBOUND TO NEAR AVERAGE BY THE END OF THE WEEK.

&&

.APX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 PM EST SATURDAY... MIZ016-017-019>022-025-026-031 WINTER WX ADVISORY...UNTIL 7 PM EST SATURDAY.. MIZ027-032.

&&

$$

...SEVERAL DAYS OF VERY COLD AIR EXPECTED THIS WEEKEND INTO NEXT WEEK...

.DISCUSSION... MAIN CONCERN WITH THE UPDATE THIS MORNING IS HANDLING OF CURRENT HEADLINES ACROSS THE CWFA. A VERY COMPLICATED SCENARIO IS SHAPING UP FOR THE NEXT SEVERAL DAYS...WITH PERIODIC SURGES OF ARCTIC AIR ACCOMPANYING SHORT WAVE PASSAGES. IN THE SHORT TERM...WHICH WAS THE PERIOD OF FOCUS FOR THE UPDATE...THE SHORTWAVE MOVING EASTWARD FROM THE NORTHERN PLAINS WILL SWEEP THROUGH THE AREA TONIGHT THROUGH EARLY FRIDAY. THE ARCTIC BOUNDARY IS CURRENTLY SAGGING SOUTH ACROSS LAKE SUPERIOR...AND THIS BOUNDARY WILL SURGE A BIT FARTHER SOUTH TONIGHT THROUGH EARLY FRIDAY AS THE SHORTWAVE SWINGS THROUGH...BUT WILL THEN DRIFT BACK TO THE NORTH LATE FRIDAY AFTERNOON INTO FRIDAY NIGHT...BEFORE IT IS DEPRESSED SOUTHWARD AGAIN BY ANOTHER SHORTWAVE FRIDAY NIGHT AND SATURDAY. THAT SECOND SHORTWAVE IS CURRENTLY ROTATING AROUND THE WESTERN PERIPHERY OF THE EASTERN CANADA UPPER LOW AND CAN BE SEEN DROPPING SOUTHWARD THROUGH CENTRAL CANADA.

LOCATIONS THAT WILL BE IMPACTED BY SIGNIFICANT LAKE ENHANCED SNOW TONIGHT AND FRIDAY IS TOUGH TO PIN DOWN SINCE MUCH WILL DEPEND ON THE BOUNDARY LAYER WIND FLOW. OTHER FACTORS ARE ALL SUGGESTING THE POTENTIAL OF A GOOD LAKE ENHANCED EVENT...WITH DECENT Q-VECTOR CONVERGENCE...DEEP MOISTURE (APPARENT ON 12Z KINL SOUNDING)...GOOD SNOW GROWTH POTENTIAL IN THE POSITIVE AREA OF THE CBL...AND SIGNIFICANT LOW LEVEL CONVERGENCE OWING TO THE ARCTIC FRONTAL BOUNDARY AND SIGNIFICANTLY BACKED LOW LEVEL WINDS SOUTH OF THE FRONT GIVEN THE SHARP TEMPERATURE CONTRAST FROM LAKE TO LAKE. THE WESTERN CWFA SEEMS SOMEWHAT STRAIGHTFORWARD...WITH CONVERGENCE ALONG THE FRONTAL BOUNDARY GIVING DECENT SNOW SHOWERS TO THE KEWEENAW THIS AFTERNOON...THEN DROPPING SOUTH THROUGH ONTONAGON AND INTO GOGEBIC COUNTY THIS EVENING. BEHIND THE FRONT...NORTHERLY WINDS SHOULD STILL HAVE ENOUGH FETCH GIVEN THE OTHER FAVORABLE CONDITIONS TO KEEP SNOW SHOWERS GOING OVER THE KEWEENAW. THE BOUNDARY WILL LIFT BACK TO THE NORTH ON FRIDAY...BRINGING THINGS TO AN END OVER GOGEBIC AND ONTONAGON COUNTIES...BUT THEN IT APPEARS THE CONVERGENCE AXIS MAY STALL OVER THE KEWEENAW AND LINGER THERE UNTIL THE NEXT SHORTWAVE ARRIVES. WITH THESE IDEAS...UPGRADED THE WATCHES TO WARNINGS OVER THE WEST...AND KEPT IT GOING FOR AN EXTENDED PERIOD OVER THE KEWEENAW SINCE ALTHOUGH THERE MAY BE LULLS IN THE ACTIVITY...GENERALLY POOR CONDITIONS WILL PERSIST THROUGH SATURDAY.

FARTHER EAST...THINGS ARE MORE DIFFICULT TO ASSESS...SINCE BOUNDARY LAYER WIND DIRECTIONS LOOK PARTICULARY TROUBLING. USED A VARIETY OF GUIDANCE...INCLUDING THE 12Z NAM...RUC13...LOCAL 20KM AND 5KM WRF-ARW...AND REGIONAL GEM TO HELP DETERMINE HOW THINGS WILL EVOLVE OVER NORTH CENTRAL UPPER MICHIGAN. THERE IS GENERAL AGREEMENT THAT THE BOUNDARY AND ASSOCIATED CONVERGENCE AXIS WILL MOVE INTO THE AREA LATE TONIGHT AND LINGER INTO FRIDAY AFTERNOON. HOWEVER...WITH ALL OF THE MODELS SUGGESTING A CLOSED LOW OVER SOUTHEAST LAKE SUPERIOR...THE BL WIND DIRECTIONS VARY CONSIDERABLY DEPENDING ON EXACTLY WHERE THAT LOW WILL BE LOCATED. THE NAM IS FARTHEST WEST...AND WOULD PRODUCE THE MOST PROLONGED PERIOD OF FAVORABLE CONDITIONS AND CONVERGENCE OVER NORTHERN AND EASTERN MARQUETTE COUNTIES...WHILE MOST OF THE OTHER GUIDANCE IS FARTHER EAST AND WOULD ONLY GIVE THE FAR NORTHEAST PORTION OF MARQUETTE COUNTY A BRIEF BOUT OF HEAVIER SNOW SHOWER ACTIVITY. THE RUC13 HAS DONE EXCEPTIONALLY WELL WITH BL WINDS OF LATE...SO LEANED MORE HEAVILY TOWARD ITS SLIGHTLY FARTHER EAST SOLUTION...WHICH NEVER REALLY BRINGS NE 925-850MB WINDS INTO MARQUETTE COUNTY AS THE NAM DOES. IF THE NAM VERIFIES...THEN FAR NORTHERN AND EASTERN MARQUETTE COUNTY...INCLUDING THE CITY...COULD SEE WARNING SNOWFALL AMOUNTS WITH 3 TO 4 INCH PER HOUR RATES FRIDAY MORNING. GIVEN THE UNCERTAINTY AND GENERALLY FARTHER EAST SOLUTIONS OF THE OTHER MODELS...WILL JUST ISSUE AND ADVISORY FOR MARQUETTE COUNTY AT THIS TIME...PARTICULARLY SINCE ONLY A SMALL PORTION OF THE COUNTY WILL BE SIGNIFICANTLY IMPACTED IN EITHER SCENARIO. ALSO PUT UP AN ADVISORY FOR ALGER COUNTY. ALTHOUGH CONDITIONS WILL BE MORE FAVORABLE FOR ALGER...THE PROGRESSIVELY BACKING WINDS FRIDAY INTO FRIDAY EVENING THROUGH KEEP ANY SPECIFIC LOCATION FROM BEING IMPACTED BY HEAVIER SNOW FOR AN EXTENDED PERIOD. LATER SHIFTS WILL DEFINITELY NEED TO KEEP AN EYE ON THINGS...SINCE SUBTLE DIFFERENCES IN THE SURFACE LOW LOCATION AND WIND FIELD WILL HAVE A BIG IMPACT ON THE LOCATIONS IMPACTED. ADVISORIES MAY EVENTUALLY BE NEEDED FOR NORTHERN SCHOOLCRAFT AND LUCE COUNTIES AS WELL...BUT SINCE THEY WILL NOT BE IMPACTED UNTIL LATER IN THE DAY ON FRIDAY...LEFT THEM OUT OF THE HEADLINE SCENARIO FOR NOW.

TRH

&&

.PREV DISCUSSION... MAIN FCST ISSUES REVOLVE LES OVER THE NW FCST AREA TODAY/THIS EVENING....POSSIBLE SIGNIFICANT LAKE EFFECT/LAKE ENHANCED EVENT LATE TONIGHT/FRI WITH SHORTWAVE PASSAGE...AND THEN THE VERY COLD AIR TO SETTLE OVER THE AREA IN ITS WAKE.

WATER VAPOR IMAGERY AND GFS ANALYSIS CONTINUE TO SHOW A VERY PRONOUNCED RIDGE ALONG THE W COAST OF NAMERICA WITH 500MB HEIGHTS AROUND 5750M ALONG THE SHORE OF FAR SE ALASKA. IN THAT AREA...THE HEIGHT ANOMALY IS A WHOPPING 400M ABOVE THE AVERAGE FOR THIS TIME OF YEAR. DOWNSTREAM OF THIS HUGE POSITIVE ANOMALY...A TROF COVERS A GOOD PORTION OF CNTRL/ERN NAMERICA WITH CORE OF POLAR VORTEX CONTINUING TO DEEPEN OVER NRN HUDSON BAY WHERE HEIGHTS ARE AROUND 4780M. CLOSER TO HOME...ONE SHORTWAVE IS TRACKING E THRU THE GREAT LAKES REGION. SFC TROF ASSOCIATED WITH THIS FEATURE RUNS FROM A POSSIBLE MESOLOW OVER FAR NE LAKE SUPERIOR TO NEAR COPPER HARBOR THEN TO THE APOSTLES. MID EVENING TAMDAR SOUNDING FROM KDLH SHOWED INVERSION AT 840MB (5KFT MSL) WITH 850MB TEMP OF -18C. PROFILE WAS MOIST THRU 600MB. WITH FOCUSED CONVERGENCE...CONDITIONS ARE FAVORABLE FOR MDT/HVY LES...ESPECIALLY CONSIDERING RELATIVELY DEEP LAYER OF FAVORABLE DENDRITIC SNOW GROWTH TEMPS BLO INVERSION. KEWEENAW COUNTY SHERIFF AT EAGLE RIVER IN FACT DID REPORT A PERIOD OF HVY SNOW WITH 4-6 INCHES OF ACCUMULATION BTWN 530Z AND 08Z AS LES BAND SHIFTED SE. BAND APPEARS TO BE SOMEWHERE BETWEEN HOUGHTON AND COPPER HARBOR AT 0930Z. NEXT SHORTWAVE TROF OF INTEREST WAS HEADING S THRU NW ONTARIO/MANITOBA/SASKATCHEWAN. IT IS THIS SYSTEM THAT WILL BRING THE ARCTIC AIR S INTO THE GREAT LAKES AND MIDWEST. ARCTIC COLD FRONT ASSOCIATED WITH SHORTWAVE IS CLEARLY EVIDENT IN SFC OBS AS THERE IS A SHARP WIND SHIFT FROM NW ONTARIO TO ND/SASKATCHEWAN BORDER

FCST TODAY IS EXTREMELY COMPLICATED FOR THE KEWEENAW DUE TO SFC TROFFING ACROSS THE LAKE AND UNCERTAIN SFC WIND FIELD EVOLUTION. RUC13 WHICH HAS FREQUENTLY HAD SUPERIOR PERFORMANCE WITH WIND FIELDS OVER LAKE SUPERIOR/NRN LAKE MICHIGAN SHOWS TROF HANGING UP OVER NW UPPER MI FROM JUST OFFSHORE OF ONTONAGON NE ACROSS THE KEWEENAW. IT WOULD POINT TO PERSISTENT LES FROM JUST S OF HOUGHTON NORTHWARD. NAM BRINGS TROF ACROSS THE KEWEENAW THIS MORNING...BUT IT THEN DEVELOPS CONVERGENT WRLY WINDS INTO THE KEWEENAW IN THE AFTN. LOCAL HIGH RESOLUTION WRF-ARW LOOKS LIKE THE RUC13 THIS MORNING...BUT THEN IT SHIFTS CONVERGENCE N OF THE KEWEENAW THIS AFTN. DIFFICULT TO SAY WHICH IF ANY OF THESE SOLUTIONS WILL WORK OUT...BUT THE RUC13 DOES HAVE RECENT HISTORY OF OUTSTANDING PERFORMANCE. WILL LEAN IN ITS DIRECTION...SO NEXT QUESTION IS SNOW INTENSITY. UPSTREAM 00Z KINL SOUNDING SHOWED INVERSION AT 880MB (3.3KFT MSL) WITH SHARP DRYING ABOVE. THIS IS A SIGNIFICANT DIFFERENCE FROM MID EVENING KDLH TAMDAR SOUNDING WHICH WAS MUCH MORE FAVORABLE FOR LES. NAM/GFS FCST SOUNDINGS SOMEWHAT REFLECT THIS DRYING AND LOWERING OF INVERSION AT KCMX DURING THE MORNING. SO...ONE WOULD EXPECT A DIMINISHING OF LES THAT IS OCCURRING OVER THE KEWEENAW RIGHT NOW. GIVEN REPORT AT EAGLE RIVER...WILL GO WITH AN ADVY THIS MORNING FOR NRN HOUGHTON/KEWEENAW WITH EXPECTATION THAT MAIN SNOW BAND WILL DIMINISH BY LATE MORNING DUE TO DRYING AND LOWERING OF INVERSION. IT`S POSSIBLE MAIN SNOW BAND MAY BE JUST ABOUT OUT OF KEWEENAW COUNTY...BUT THERE IS NO WAY TO KNOW FOR SURE RIGHT NOW. OTHERWISE...EXPECT DRY WEATHER ELSEWHERE TODAY AFTER A FEW FLURRIES EARLY. THE TROF OVER LAKE SUPERIOR MAY SAG S TOWARD THE SRN PORTION OF THE ERN LAKE TODAY...BUT IT APPEARS WIND DIRECTION OVER UPPER MI WILL RETAIN ENOUGH OF A SRLY COMPONENT TO KEEP LES OFFSHORE OF THE ERN FCST AREA.

FCST DOES NOT GET ANY EASIER TONIGHT/FRI. AGAIN...ALL THE COMPLICATIONS REVOLVE AROUND THE WIND FIELDS. SHORTWAVE TROF OVER SRN CANADA APPROACHES TONIGHT...BUT ENERGY TENDS TO FOCUS IN SW END OF TROF WITH TIME. THE RESULT TONIGHT IS THAT THE ARCTIC FRONT WILL MOVE OVER LAKE SUPERIOR...AND THEN BECOME NEARLY STATIONARY UNTIL THE CONSOLIDATING ENERGY IN SHORTWAVE TROF TRACKS THRU THE UPPER LAKES FRI. DESPITE THE DIFFERENCES IN WIND FIELDS TODAY...THE RUC13 AND NAM LOOK SIMILAR BY THE 06Z-12Z TIME FRAME. ARCTIC FRONT WILL REACH THE KEWEENAW AT SOME POINT THIS EVENING AND THEN IT SHOULD SLOW OR HANG UP FROM NEAR OR SE OF THE APOSTLES TO NEAR HOUGHTON AND TO SE LAKE SUPERIOR WHERE MAIN SFC LOW WILL BEGIN TO ORGANIZE/DEEPEN. LOW-LEVEL CONVERGENCE/GRADUAL INCREASE IN DEEP LAYER FORCING AND DEEP MOISTENING OF COLUMN STRONGLY ARGUE FOR THE DEVELOPMENT OF HVY LAKE ENHANCED SNOW (ESPECIALLY ALONG ARCTIC FRONT) SINCE 850MB TEMPS ARE ALREADY LOW AROUND -18C. ALTHOUGH THERE IS A BIT MORE CONFIDENCE IN PLACEMENT OF ARCTIC FRONT OVERNIGHT... WIND FIELDS WILL STILL BE TROUBLESOME FOR PINPOINTING LOCATIONS OF HEAVIEST SNOW. RUC13 HAS MESOLOW DEVELOPMENT OVERNIGHT ALONG FRONT BTWN APOSTLES AND PORCUPINE MTNS. THIS COMBINED WITH SFC LOW DEVELOPMENT OVER SE LAKE SUPERIOR RESULTS IN DIVERGENT WIND FLOW DEVELOPING IN VCNTY OF FRONT OVER THE KEWEENAW. ALTHOUGH THAT`S POSSIBLE...STILL THINK THE VERY FAVORABLE LAKE ENHANCEMENT CONDITIONS WILL LEAD TO HVY SNOW THERE. HAVE OPTED TO RETAIN WATCH...BUT DID START TIMING EARLY THIS EVENING AND CARRIED WATCH THRU SAT MORNING (MORE ON THAT LATER). FOLLOWING NAM/RUC13 SOLUTIONS...HEAVIER SNOW WILL NOT START OVER ONTONAGON/GOGEBIC COUNTIES UNTIL AFTER MIDNIGHT WHEN WINDS FINALLY SHIFT AROUND TO THE N OR NW. LAKE ENHANCMENT PERIOD WILL BE SHORT FOR GOGEBIC COUNTY AS WINDS BACK W OR EVEN SW FRI. STILL...MIGHT BE ABLE TO PICK UP A QUICK 8 INCHES GIVEN SUCH FAVORABLE LAKE ENHANCEMENT CONDITIONS. AT LEAST A BRIEF PERIOD OF VERY HVY SNOW WILL SWEEP ACROSS MARQUETTE/ALGER/LUCE COUNTIES FRI AS DEEPENING LOW SHIFTS E OF LAKE SUPERIOR AND ARCTIC FRONT HEADS SE. SHOULD EASILY BE AN ADVY TYPE EVENT.

ANOTHER SHORTWAVE WILL ROTATE SE INTO THE UPPER LAKES FRI NIGHT AS POLAR VORTEX HEADS S. THIS WILL BRING ANOTHER ROUND OF HVY LAKE ENHANCED SNOW...AND ANOTHER SFC LOW WILL LIKELY DEVELOP OVER ERN LAKE SUPERIOR. THIS WILL RESULT IN CONVERGENT LOW-LEVEL WIND FLOW INTO NW UPPER MI. AIRMASS WILL NOT QUITE BE TOO COLD YET TO PRECLUDE DECENT SNOW GROWTH MICROPHYSICS...SO SNOW ACCUMULATIONS COULD BE HVY...ESPECIALLY CONSIDERING THE LOW-LEVEL CONVERGENCE. DEVELOPMENT OF ERN LAKE SUPERIOR LOW PRES AND STRENGTHENING LAND BREEZE WILL LIKELY RESULT IN WINDS BACKING ENOUGH TO KEEP HEAVIEST LES OFFSHORE OF THE NE FCST AREA FRI NIGHT. OVER THE WEEKEND AND INTO EARLY NEXT WEEK...THE COLDEST AIR OF THE SEASON WILL SETTLE OVER THE AREA. CONSENSUS OF THE LAST FEW DAYS OF ECWMF/GFS RUNS IS THAT 850MB TEMPS WILL BOTTOM OUT IN THE -28 TO -32C RANGE. NOGAPS AND SEVERAL RECENT LOCAL HEMISPHERIC WRF-ARW RUNS HAVE INDICATED 850MB TEMPS A FEW DEGREES LWR. IN ANYCASE...IT IS POSSIBLE THAT A FEW LOCATIONS OVER THE W HALF OF UPPER MI AWAY FROM LAKE SUPERIOR INFLUENCE MAY SEE TEMPS REMAIN BLO ZERO FROM FRI NIGHT UNTIL TUE AFTN. MIN TEMPS WILL DEPEND ON CLOUD COVER/WINDS...BUT -10F TO -20F SHOULD BE THE RULE AWAY FROM LAKE SUPERIOR INFLUENCE. AS FOR LAKE EFFECT...GFS FCST SOUNDINGS INDICATE AIRMASS REMAINING FAIRLY MOIST WITH HIGH INVERSIONS 8KFT TO AS MUCH AS 15KFT. HOWEVER...AN OVERWHELMING NEGATIVE FOR SIGNIFICANT SNOW IS THE VERY COLD AIR WHICH WILL SEVERELY LIMIT SNOWFLAKE GROWTH AND THUS ACCUMULATIONS. IT WILL BE INTERESTING THOUGH TO SEE IF LOCAL CONVERGENCE ZONES STRENGTHENED BY LAND BREEZES WILL BE ABLE TO YIELD HEAVIER LES BANDS AND SIGNIFICANT SNOW IN SUCH A COLD AIRMASS. ALTHOUGH ACCUMULATIONS ARE EXPECTED TO BE FAIRLY LIGHT EACH DAY...DURING SNOW SHOWERS THE AIR WILL BE THICK WITH SMALL SNOWFLAKES WHICH WILL BE EXTREMELY EFFECTIVE AT REDUCING VISIBILITY TO NEAR ZERO.

ROLFSON

&&

.MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING THROUGH 6PM EST SATURDAY MIZ001-003. WINTER STORM WARNING 10 PM EST THIS EVENING THROUGH 4 PM EST FRIDAY MIZ002. WINTER STORM WARNING 9 PM CST THIS EVENING THROUGH 9 AM CST FRIDAY MIZ009. WINTER STORM WARNING MIDNIGHT EST TONIGHT THROUGH 4 PM EST FRIDAY MIZ084. WINTER WEATHER ADVISORY MIDNIGHT EST TONIGHT THROUGH 4 PM EST FRIDAY MIZ004. WINTER WEATHER ADVISORY 1 AM EST TONIGHT THROUGH 4 PM EST FRIDAY MIZ005. WINTER WEATHER ADVISORY 7 AM EST THROUGH 10 PM EST FRIDAY MIZ006. HEAVY FREEZING SPRAY WARNING W HALF OF LAKE SUPERIOR.

&&

$$

...SEVERAL DAYS OF VERY COLD AIR EXPECTED THIS WEEKEND INTO NEXT WEEK...

.DISCUSSION... MAIN FCST ISSUES REVOLVE LES OVER THE NW FCST AREA TODAY/THIS EVENING....POSSIBLE SIGNIFICANT LAKE EFFECT/LAKE ENHANCED EVENT LATE TONIGHT/FRI WITH SHORTWAVE PASSAGE...AND THEN THE VERY COLD AIR TO SETTLE OVER THE AREA IN ITS WAKE.

WATER VAPOR IMAGERY AND GFS ANALYSIS CONTINUE TO SHOW A VERY PRONOUNCED RIDGE ALONG THE W COAST OF NAMERICA WITH 500MB HEIGHTS AROUND 5750M ALONG THE SHORE OF FAR SE ALASKA. IN THAT AREA...THE HEIGHT ANOMALY IS A WHOPPING 400M ABOVE THE AVERAGE FOR THIS TIME OF YEAR. DOWNSTREAM OF THIS HUGE POSITIVE ANOMALY...A TROF COVERS A GOOD PORTION OF CNTRL/ERN NAMERICA WITH CORE OF POLAR VORTEX CONTINUING TO DEEPEN OVER NRN HUDSON BAY WHERE HEIGHTS ARE AROUND 4780M. CLOSER TO HOME...ONE SHORTWAVE IS TRACKING E THRU THE GREAT LAKES REGION. SFC TROF ASSOCIATED WITH THIS FEATURE RUNS FROM A POSSIBLE MESOLOW OVER FAR NE LAKE SUPERIOR TO NEAR COPPER HARBOR THEN TO THE APOSTLES. MID EVENING TAMDAR SOUNDING FROM KDLH SHOWED INVERSION AT 840MB (5KFT MSL) WITH 850MB TEMP OF -18C. PROFILE WAS MOIST THRU 600MB. WITH FOCUSED CONVERGENCE...CONDITIONS ARE FAVORABLE FOR MDT/HVY LES...ESPECIALLY CONSIDERING RELATIVELY DEEP LAYER OF FAVORABLE DENDRITIC SNOW GROWTH TEMPS BLO INVERSION. KEWEENAW COUNTY SHERIFF AT EAGLE RIVER IN FACT DID REPORT A PERIOD OF HVY SNOW WITH 4-6 INCHES OF ACCUMULATION BTWN 530Z AND 08Z AS LES BAND SHIFTED SE. BAND APPEARS TO BE SOMEWHERE BETWEEN HOUGHTON AND COPPER HARBOR AT 0930Z. NEXT SHORTWAVE TROF OF INTEREST WAS HEADING S THRU NW ONTARIO/MANITOBA/SASKATCHEWAN. IT IS THIS SYSTEM THAT WILL BRING THE ARCTIC AIR S INTO THE GREAT LAKES AND MIDWEST. ARCTIC COLD FRONT ASSOCIATED WITH SHORTWAVE IS CLEARLY EVIDENT IN SFC OBS AS THERE IS A SHARP WIND SHIFT FROM NW ONTARIO TO ND/SASKATCHEWAN BORDER

FCST TODAY IS EXTREMELY COMPLICATED FOR THE KEWEENAW DUE TO SFC TROFFING ACROSS THE LAKE AND UNCERTAIN SFC WIND FIELD EVOLUTION. RUC13 WHICH HAS FREQUENTLY HAD SUPERIOR PERFORMANCE WITH WIND FIELDS OVER LAKE SUPERIOR/NRN LAKE MICHIGAN SHOWS TROF HANGING UP OVER NW UPPER MI FROM JUST OFFSHORE OF ONTONAGON NE ACROSS THE KEWEENAW. IT WOULD POINT TO PERSISTENT LES FROM JUST S OF HOUGHTON NORTHWARD. NAM BRINGS TROF ACROSS THE KEWEENAW THIS MORNING...BUT IT THEN DEVELOPS CONVERGENT WRLY WINDS INTO THE KEWEENAW IN THE AFTN. LOCAL HIGH RESOLUTION WRF-ARW LOOKS LIKE THE RUC13 THIS MORNING...BUT THEN IT SHIFTS CONVERGENCE N OF THE KEWEENAW THIS AFTN. DIFFICULT TO SAY WHICH IF ANY OF THESE SOLUTIONS WILL WORK OUT...BUT THE RUC13 DOES HAVE RECENT HISTORY OF OUTSTANDING PERFORMANCE. WILL LEAN IN ITS DIRECTION...SO NEXT QUESTION IS SNOW INTENSITY. UPSTREAM 00Z KINL SOUNDING SHOWED INVERSION AT 880MB (3.3KFT MSL) WITH SHARP DRYING ABOVE. THIS IS A SIGNIFICANT DIFFERENCE FROM MID EVENING KDLH TAMDAR SOUNDING WHICH WAS MUCH MORE FAVORABLE FOR LES. NAM/GFS FCST SOUNDINGS SOMEWHAT REFLECT THIS DRYING AND LOWERING OF INVERSION AT KCMX DURING THE MORNING. SO...ONE WOULD EXPECT A DIMINISHING OF LES THAT IS OCCURRING OVER THE KEWEENAW RIGHT NOW. GIVEN REPORT AT EAGLE RIVER...WILL GO WITH AN ADVY THIS MORNING FOR NRN HOUGHTON/KEWEENAW WITH EXPECTATION THAT MAIN SNOW BAND WILL DIMINISH BY LATE MORNING DUE TO DRYING AND LOWERING OF INVERSION. IT`S POSSIBLE MAIN SNOW BAND MAY BE JUST ABOUT OUT OF KEWEENAW COUNTY...BUT THERE IS NO WAY TO KNOW FOR SURE RIGHT NOW. OTHERWISE...EXPECT DRY WEATHER ELSEWHERE TODAY AFTER A FEW FLURRIES EARLY. THE TROF OVER LAKE SUPERIOR MAY SAG S TOWARD THE SRN PORTION OF THE ERN LAKE TODAY...BUT IT APPEARS WIND DIRECTION OVER UPPER MI WILL RETAIN ENOUGH OF A SRLY COMPONENT TO KEEP LES OFFSHORE OF THE ERN FCST AREA.

FCST DOES NOT GET ANY EASIER TONIGHT/FRI. AGAIN...ALL THE COMPLICATIONS REVOLVE AROUND THE WIND FIELDS. SHORTWAVE TROF OVER SRN CANADA APPROACHES TONIGHT...BUT ENERGY TENDS TO FOCUS IN SW END OF TROF WITH TIME. THE RESULT TONIGHT IS THAT THE ARCTIC FRONT WILL MOVE OVER LAKE SUPERIOR...AND THEN BECOME NEARLY STATIONARY UNTIL THE CONSOLIDATING ENERGY IN SHORTWAVE TROF TRACKS THRU THE UPPER LAKES FRI. DESPITE THE DIFFERENCES IN WIND FIELDS TODAY...THE RUC13 AND NAM LOOK SIMILAR BY THE 06Z-12Z TIME FRAME. ARCTIC FRONT WILL REACH THE KEWEENAW AT SOME POINT THIS EVENING AND THEN IT SHOULD SLOW OR HANG UP FROM NEAR OR SE OF THE APOSTLES TO NEAR HOUGHTON AND TO SE LAKE SUPERIOR WHERE MAIN SFC LOW WILL BEGIN TO ORGANIZE/DEEPEN. LOW-LEVEL CONVERGENCE/GRADUAL INCREASE IN DEEP LAYER FORCING AND DEEP MOISTENING OF COLUMN STRONGLY ARGUE FOR THE DEVELOPMENT OF HVY LAKE ENHANCED SNOW (ESPECIALLY ALONG ARCTIC FRONT) SINCE 850MB TEMPS ARE ALREADY LOW AROUND -18C. ALTHOUGH THERE IS A BIT MORE CONFIDENCE IN PLACEMENT OF ARCTIC FRONT OVERNIGHT... WIND FIELDS WILL STILL BE TROUBLESOME FOR PINPOINTING LOCATIONS OF HEAVIEST SNOW. RUC13 HAS MESOLOW DEVELOPMENT OVERNIGHT ALONG FRONT BTWN APOSTLES AND PORCUPINE MTNS. THIS COMBINED WITH SFC LOW DEVELOPMENT OVER SE LAKE SUPERIOR RESULTS IN DIVERGENT WIND FLOW DEVELOPING IN VCNTY OF FRONT OVER THE KEWEENAW. ALTHOUGH THAT`S POSSIBLE...STILL THINK THE VERY FAVORABLE LAKE ENHANCEMENT CONDITIONS WILL LEAD TO HVY SNOW THERE. HAVE OPTED TO RETAIN WATCH...BUT DID START TIMING EARLY THIS EVENING AND CARRIED WATCH THRU SAT MORNING (MORE ON THAT LATER). FOLLOWING NAM/RUC13 SOLUTIONS...HEAVIER SNOW WILL NOT START OVER ONTONAGON/GOGEBIC COUNTIES UNTIL AFTER MIDNIGHT WHEN WINDS FINALLY SHIFT AROUND TO THE N OR NW. LAKE ENHANCMENT PERIOD WILL BE SHORT FOR GOGEBIC COUNTY AS WINDS BACK W OR EVEN SW FRI. STILL...MIGHT BE ABLE TO PICK UP A QUICK 8 INCHES GIVEN SUCH FAVORABLE LAKE ENHANCEMENT CONDITIONS. AT LEAST A BRIEF PERIOD OF VERY HVY SNOW WILL SWEEP ACROSS MARQUETTE/ALGER/LUCE COUNTIES FRI AS DEEPENING LOW SHIFTS E OF LAKE SUPERIOR AND ARCTIC FRONT HEADS SE. SHOULD EASILY BE AN ADVY TYPE EVENT.

ANOTHER SHORTWAVE WILL ROTATE SE INTO THE UPPER LAKES FRI NIGHT AS POLAR VORTEX HEADS S. THIS WILL BRING ANOTHER ROUND OF HVY LAKE ENHANCED SNOW...AND ANOTHER SFC LOW WILL LIKELY DEVELOP OVER ERN LAKE SUPERIOR. THIS WILL RESULT IN CONVERGENT LOW-LEVEL WIND FLOW INTO NW UPPER MI. AIRMASS WILL NOT QUITE BE TOO COLD YET TO PRECLUDE DECENT SNOW GROWTH MICROPHYSICS...SO SNOW ACCUMULATIONS COULD BE HVY...ESPECIALLY CONSIDERING THE LOW-LEVEL CONVERGENCE. DEVELOPMENT OF ERN LAKE SUPERIOR LOW PRES AND STRENGTHENING LAND BREEZE WILL LIKELY RESULT IN WINDS BACKING ENOUGH TO KEEP HEAVIEST LES OFFSHORE OF THE NE FCST AREA FRI NIGHT. OVER THE WEEKEND AND INTO EARLY NEXT WEEK...THE COLDEST AIR OF THE SEASON WILL SETTLE OVER THE AREA. CONSENSUS OF THE LAST FEW DAYS OF ECWMF/GFS RUNS IS THAT 850MB TEMPS WILL BOTTOM OUT IN THE -28 TO -32C RANGE. NOGAPS AND SEVERAL RECENT LOCAL HEMISPHERIC WRF-ARW RUNS HAVE INDICATED 850MB TEMPS A FEW DEGREES LWR. IN ANYCASE...IT IS POSSIBLE THAT A FEW LOCATIONS OVER THE W HALF OF UPPER MI AWAY FROM LAKE SUPERIOR INFLUENCE MAY SEE TEMPS REMAIN BLO ZERO FROM FRI NIGHT UNTIL TUE AFTN. MIN TEMPS WILL DEPEND ON CLOUD COVER/WINDS...BUT -10F TO -20F SHOULD BE THE RULE AWAY FROM LAKE SUPERIOR INFLUENCE. AS FOR LAKE EFFECT...GFS FCST SOUNDINGS INDICATE AIRMASS REMAINING FAIRLY MOIST WITH HIGH INVERSIONS 8KFT TO AS MUCH AS 15KFT. HOWEVER...AN OVERWHELMING NEGATIVE FOR SIGNIFICANT SNOW IS THE VERY COLD AIR WHICH WILL SEVERELY LIMIT SNOWFLAKE GROWTH AND THUS ACCUMULATIONS. IT WILL BE INTERESTING THOUGH TO SEE IF LOCAL CONVERGENCE ZONES STRENGTHENED BY LAND BREEZES WILL BE ABLE TO YIELD HEAVIER LES BANDS AND SIGNIFICANT SNOW IN SUCH A COLD AIRMASS. ALTHOUGH ACCUMULATIONS ARE EXPECTED TO BE FAIRLY LIGHT EACH DAY...DURING SNOW SHOWERS THE AIR WILL BE THICK WITH SMALL SNOWFLAKES WHICH WILL BE EXTREMELY EFFECTIVE AT REDUCING VISIBILITY TO NEAR ZERO.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL NOON EST MIZ001-003. WINTER STORM WATCH THIS EVENING THRU SAT MORNING MIZ001-003. WINTER STORM WATCH LATE TONIGHT THRU FRI AFTN MIZ002-004-009-084. HEAVY FREEZING SPRAY WARNING W HALF OF LAKE SUPERIOR.

&&

$$

ROLFSON

...SEVERAL DAYS OF VERY COLD AIR EXPECTED THIS WEEKEND INTO NEXT WEEK... .DISCUSSION... MAIN FCST ISSUES REVOLVE LES OVER THE NW FCST AREA TODAY/THIS EVENING....POSSIBLE SIGNIFICANT LAKE EFFECT/LAKE ENHANCED EVENT LATE TONIGHT/FRI WITH SHORTWAVE PASSAGE...AND THEN THE VERY COLD AIR TO SETTLE OVER THE AREA IN ITS WAKE. WATER VAPOR IMAGERY AND GFS ANALYSIS CONTINUE TO SHOW A VERY PRONOUNCED RIDGE ALONG THE W COAST OF NAMERICA WITH 500MB HEIGHTS AROUND 5750M ALONG THE SHORE OF FAR SE ALASKA. IN THAT AREA...THE HEIGHT ANOMALY IS A WHOPPING 400M ABOVE THE AVERAGE FOR THIS TIME OF YEAR. DOWNSTREAM OF THIS HUGE POSITIVE ANOMALY...A TROF COVERS A GOOD PORTION OF CNTRL/ERN NAMERICA WITH CORE OF POLAR VORTEX CONTINUING TO DEEPEN OVER NRN HUDSON BAY WHERE HEIGHTS ARE AROUND 4780M. CLOSER TO HOME...ONE SHORTWAVE IS TRACKING E THRU THE GREAT LAKES REGION. SFC TROF ASSOCIATED WITH THIS FEATURE RUNS FROM A POSSIBLE MESOLOW OVER FAR NE LAKE SUPERIOR TO NEAR COPPER HARBOR THEN TO THE APOSTLES. MID EVENING TAMDAR SOUNDING FROM KDLH SHOWED INVERSION AT 840MB (5KFT MSL) WITH 850MB TEMP OF -18C. PROFILE WAS MOIST THRU 600MB. WITH FOCUSED CONVERGENCE...CONDITIONS ARE FAVORABLE FOR MDT/HVY LES...ESPECIALLY CONSIDERING RELATIVELY DEEP LAYER OF FAVORABLE DENDRITIC SNOW GROWTH TEMPS BLO INVERSION. KEWEENAW COUNTY SHERIFF AT EAGLE RIVER IN FACT DID REPORT A PERIOD OF HVY SNOW WITH 4-6 INCHES OF ACCUMULATION BTWN 530Z AND 08Z AS LES BAND SHIFTED SE. BAND APPEARS TO BE SOMEWHERE BETWEEN HOUGHTON AND COPPER HARBOR AT 0930Z. NEXT SHORTWAVE TROF OF INTEREST WAS HEADING S THRU NW ONTARIO/MANITOBA/SASKATCHEWAN. IT IS THIS SYSTEM THAT WILL BRING THE ARCTIC AIR S INTO THE GREAT LAKES AND MIDWEST. ARCTIC COLD FRONT ASSOCIATED WITH SHORTWAVE IS CLEARLY EVIDENT IN SFC OBS AS THERE IS A SHARP WIND SHIFT FROM NW ONTARIO TO ND/SASKATCHEWAN BORDER FCST TODAY IS EXTREMELY COMPLICATED FOR THE KEWEENAW DUE TO SFC TROFFING ACROSS THE LAKE AND UNCERTAIN SFC WIND FIELD EVOLUTION. RUC13 WHICH HAS FREQUENTLY HAD SUPERIOR PERFORMANCE WITH WIND FIELDS OVER LAKE SUPERIOR/NRN LAKE MICHIGAN SHOWS TROF HANGING UP OVER NW UPPER MI FROM JUST OFFSHORE OF ONTONAGON NE ACROSS THE KEWEENAW. IT WOULD POINT TO PERSISTENT LES FROM JUST S OF HOUGHTON NORTHWARD. NAM BRINGS TROF ACROSS THE KEWEENAW THIS MORNING...BUT IT THEN DEVELOPS CONVERGENT WRLY WINDS INTO THE KEWEENAW IN THE AFTN. LOCAL HIGH RESOLUTION WRF-ARW LOOKS LIKE THE RUC13 THIS MORNING...BUT THEN IT SHIFTS CONVERGENCE N OF THE KEWEENAW THIS AFTN. DIFFICULT TO SAY WHICH IF ANY OF THESE SOLUTIONS WILL WORK OUT...BUT THE RUC13 DOES HAVE RECENT HISTORY OF OUTSTANDING PERFORMANCE. WILL LEAN IN ITS DIRECTION...SO NEXT QUESTION IS SNOW INTENSITY. UPSTREAM 00Z KINL SOUNDING SHOWED INVERSION AT 880MB (3.3KFT MSL) WITH SHARP DRYING ABOVE. THIS IS A SIGNIFICANT DIFFERENCE FROM MID EVENING KDLH TAMDAR SOUNDING WHICH WAS MUCH MORE FAVORABLE FOR LES. NAM/GFS FCST SOUNDINGS SOMEWHAT REFLECT THIS DRYING AND LOWERING OF INVERSION AT KCMX DURING THE MORNING. SO...ONE WOULD EXPECT A DIMINISHING OF LES THAT IS OCCURRING OVER THE KEWEENAW RIGHT NOW. GIVEN REPORT AT EAGLE RIVER...WILL GO WITH AN ADVY THIS MORNING FOR NRN HOUGHTON/KEWEENAW WITH EXPECTATION THAT MAIN SNOW BAND WILL DIMINISH BY LATE MORNING DUE TO DRYING AND LOWERING OF INVERSION. IT`S POSSIBLE MAIN SNOW BAND MAY BE JUST ABOUT OUT OF KEWEENAW COUNTY...BUT THERE IS NO WAY TO KNOW FOR SURE RIGHT NOW. OTHERWISE...EXPECT DRY WEATHER ELSEWHERE TODAY AFTER A FEW FLURRIES EARLY. THE TROF OVER LAKE SUPERIOR MAY SAG S TOWARD THE SRN PORTION OF THE ERN LAKE TODAY...BUT IT APPEARS WIND DIRECTION OVER UPPER MI WILL RETAIN ENOUGH OF A SRLY COMPONENT TO KEEP LES OFFSHORE OF THE ERN FCST AREA. FCST DOES NOT GET ANY EASIER TONIGHT/FRI. AGAIN...ALL THE COMPLICATIONS REVOLVE AROUND THE WIND FIELDS. SHORTWAVE TROF OVER SRN CANADA APPROACHES TONIGHT...BUT ENERGY TENDS TO FOCUS IN SW END OF TROF WITH TIME. THE RESULT TONIGHT IS THAT THE ARCTIC FRONT WILL MOVE OVER LAKE SUPERIOR...AND THEN BECOME NEARLY STATIONARY UNTIL THE CONSOLIDATING ENERGY IN SHORTWAVE TROF TRACKS THRU THE UPPER LAKES FRI. DESPITE THE DIFFERENCES IN WIND FIELDS TODAY...THE RUC13 AND NAM LOOK SIMILAR BY THE 06Z-12Z TIME FRAME. ARCTIC FRONT WILL REACH THE KEWEENAW AT SOME POINT THIS EVENING AND THEN IT SHOULD SLOW OR HANG UP FROM NEAR OR SE OF THE APOSTLES TO NEAR HOUGHTON AND TO SE LAKE SUPERIOR WHERE MAIN SFC LOW WILL BEGIN TO ORGANIZE/DEEPEN. LOW-LEVEL CONVERGENCE/GRADUAL INCREASE IN DEEP LAYER FORCING AND DEEP MOISTENING OF COLUMN STRONGLY ARGUE FOR THE DEVELOPMENT OF HVY LAKE ENHANCED SNOW (ESPECIALLY ALONG ARCTIC FRONT) SINCE 850MB TEMPS ARE ALREADY LOW AROUND -18C. ALTHOUGH THERE IS A BIT MORE CONFIDENCE IN PLACEMENT OF ARCTIC FRONT OVERNIGHT... WIND FIELDS WILL STILL BE TROUBLESOME FOR PINPOINTING LOCATIONS OF HEAVIEST SNOW. RUC13 HAS MESOLOW DEVELOPMENT OVERNIGHT ALONG FRONT BTWN APOSTLES AND PORCUPINE MTNS. THIS COMBINED WITH SFC LOW DEVELOPMENT OVER SE LAKE SUPERIOR RESULTS IN DIVERGENT WIND FLOW DEVELOPING IN VCNTY OF FRONT OVER THE KEWEENAW. ALTHOUGH THAT`S POSSIBLE...STILL THINK THE VERY FAVORABLE LAKE ENHANCEMENT CONDITIONS WILL LEAD TO HVY SNOW THERE. HAVE OPTED TO RETAIN WATCH...BUT DID START TIMING EARLY THIS EVENING AND CARRIED WATCH THRU SAT MORNING (MORE ON THAT LATER). FOLLOWING NAM/RUC13 SOLUTIONS...HEAVIER SNOW WILL NOT START OVER ONTONAGON/GOGEBIC COUNTIES UNTIL AFTER MIDNIGHT WHEN WINDS FINALLY SHIFT AROUND TO THE N OR NW. LAKE ENHANCMENT PERIOD WILL BE SHORT FOR GOGEBIC COUNTY AS WINDS BACK W OR EVEN SW FRI. STILL...MIGHT BE ABLE TO PICK UP A QUICK 8 INCHES GIVEN SUCH FAVORABLE LAKE ENHANCEMENT CONDITIONS. AT LEAST A BRIEF PERIOD OF VERY HVY SNOW WILL SWEEP ACROSS MARQUETTE/ALGER/LUCE COUNTIES FRI AS DEEPENING LOW SHIFTS E OF LAKE SUPERIOR AND ARCTIC FRONT HEADS SE. SHOULD EASILY BE AN ADVY TYPE EVENT. ANOTHER SHORTWAVE WILL ROTATE SE INTO THE UPPER LAKES FRI NIGHT AS POLAR VORTEX HEADS S. THIS WILL BRING ANOTHER ROUND OF HVY LAKE ENHANCED SNOW...AND ANOTHER SFC LOW WILL LIKELY DEVELOP OVER ERN LAKE SUPERIOR. THIS WILL RESULT IN CONVERGENT LOW-LEVEL WIND FLOW INTO NW UPPER MI. AIRMASS WILL NOT QUITE BE TOO COLD YET TO PRECLUDE DECENT SNOW GROWTH MICROPHYSICS...SO SNOW ACCUMULATIONS COULD BE HVY...ESPECIALLY CONSIDERING THE LOW-LEVEL CONVERGENCE. DEVELOPMENT OF ERN LAKE SUPERIOR LOW PRES AND STRENGTHENING LAND BREEZE WILL LIKELY RESULT IN WINDS BACKING ENOUGH TO KEEP HEAVIEST LES OFFSHORE OF THE NE FCST AREA FRI NIGHT. OVER THE WEEKEND AND INTO EARLY NEXT WEEK...THE COLDEST AIR OF THE SEASON WILL SETTLE OVER THE AREA. CONSENSUS OF THE LAST FEW DAYS OF ECWMF/GFS RUNS IS THAT 850MB TEMPS WILL BOTTOM OUT IN THE -28 TO -32C RANGE. NOGAPS AND SEVERAL RECENT LOCAL HEMISPHERIC WRF-ARW RUNS HAVE INDICATED 850MB TEMPS A FEW DEGREES LWR. IN ANYCASE...IT IS POSSIBLE THAT A FEW LOCATIONS OVER THE W HALF OF UPPER MI AWAY FROM LAKE SUPERIOR INFLUENCE MAY SEE TEMPS REMAIN BLO ZERO FROM FRI NIGHT UNTIL TUE AFTN. MIN TEMPS WILL DEPEND ON CLOUD COVER/WINDS...BUT -10F TO -20F SHOULD BE THE RULE AWAY FROM LAKE SUPERIOR INFLUENCE. AS FOR LAKE EFFECT...GFS FCST SOUNDINGS INDICATE AIRMASS REMAINING FAIRLY MOIST WITH HIGH INVERSIONS 8KFT TO AS MUCH AS 15KFT. HOWEVER...AN OVERWHELMING NEGATIVE FOR SIGNIFICANT SNOW IS THE VERY COLD AIR WHICH WILL SEVERELY LIMIT SNOWFLAKE GROWTH AND THUS ACCUMULATIONS. IT WILL BE INTERESTING THOUGH TO SEE IF LOCAL CONVERGENCE ZONES STRENGTHENED BY LAND BREEZES WILL BE ABLE TO YIELD HEAVIER LES BANDS AND SIGNIFICANT SNOW IN SUCH A COLD AIRMASS. ALTHOUGH ACCUMULATIONS ARE EXPECTED TO BE FAIRLY LIGHT EACH DAY...DURING SNOW SHOWERS THE AIR WILL BE THICK WITH SMALL SNOWFLAKES WHICH WILL BE EXTREMELY EFFECTIVE AT REDUCING VISIBILITY TO NEAR ZERO. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL NOON EST MIZ001-003. WINTER STORM WATCH THIS EVENING THRU SAT MORNING MIZ001-003. WINTER STORM WATCH LATE TONIGHT THRU FRI AFTN MIZ002-004-009-084. HEAVY FREEZING SPRAY WARNING W HALF OF LAKE SUPERIOR. && $$ ROLFSON

.UPDATE...

&&

.SHORT TERM /REST OF TODAY/...

THE INITIAL HEAVY BURST OF SNOW HAS RESULTED IN HEAVIEST SNOWFALL TOTALS ACROSS THE SOUTHERN HALF OF CWA...SEEN CLEARLY EARLIER ON THE KRAX RADAR IMAGERY WITH THE BRIGHT BAND REFLECTIVITY EXTENDING OVER THE SOUTHERN SECTOR. REPORTS INDICATE THE HIGHEST AMOUNTS ACROSS THE SOUTHWEST PIEDMONT...STANLY...ANSON...AND MONTGOMERY AND MOORE COUNTIES. 1 TO 1.5 INCHES WAS REPORTED IN THE SANDHILLS AND SOUTHERN COASTAL PLAIN...WHICH PROMPTED RAISING A WINTER WX ADVISORY THROUGH NOON. MEANWHILE ACROSS THE NORTHERN HALF...SNOW AMOUNTS ARE LESS THAN AN INCH WITH THE TRIAD AND COUNTIES ALONG THE VA BORDER REPORTING ONLY A TRACE.

CURRENTLY... REAL TIME REPORTS...AIRCRAFT(AMDAR)SOUNDINGS...AND THE MRR-VERTICALLY POINTING RADAR...ARE ALL SHOWING THE ADVERTISED WARMING NOSE ALOFT ADVANCING NORTH WITH THE MELTING LAYER STARTING TO DESCEND DOWN TO THE SURFACE. REPORTS EXTENDING FROM ALBEMARLE...MOORE... FAYETTEVILLE HAVE CHANGED OVER TO SLEET OR FREEZING RAIN. THE LATEST RUC IS MODELING THE THERMAL PROFILE FAIRLY WELL WHEN COMPARED TO THE LATEST AMDAR SOUNDING FROM GSO...WITH IT A LITTLE TOO COOL ALOFT AND SLIGHTLY TOO WARM NEAR THE SURFACE SURFACE.

WITH THE MAIN WARM/MOIST AIR CONVEYOR BELT DIRECTED IN A MORE SW TO NE FASHION AND TRANSLATING IN A MORE EASTERLY DIRECTION...RADARS RETURNS HAVE BEEN HARD TO COME BY ACROSS THE TRIAD. IT APPEARS THAT THE PREDICTED SNOWFALL OF 1 TO 2 INCHES WILL NOT BE REALIZED. HOWEVER...PRECIP WILL SPREAD BACK NORTH THIS AFTERNOON AS THE WELL-DEFINED WAVE OVER ALABAMA TRANSLATES NE TOWARDS CENTRAL NC. BY THAT TIME...THE THERMAL PROFILE WILL BE WARMING TO SUPPORT A TRANSITION TO SLEET AND THE ANTICIPATED FREEZING RAIN. THERE IS STILL YET ANOTHER WAVE OVER THE TEXAS AND OKLAHOMA THIS IS PROGGED TO APPROACH THE AREA BETWEEN 00Z TO 06Z. SO BY NO MEANS IS THE TRIAD OUT OF THE WOODS...WITH A QUARTER OF AN INCH ICE STILL VERY POSSIBLE. WILL BE KEEPING ALL WARNINGS AND ADVISORIES UP...BUT LOWER THE SNOWFALL AMOUNTS AND POPS. OTHERWISE...MINOR ADJUSTMENTS TO FORECAST OF P-TYPE AND TIMING OF CHANGEOVER.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... THE FLOW ALOFT IS DOMINATED BY A BROAD LARGE SCALE TROUGH OVER THE EASTERN TWO-THIRDS OF THE CONUS WITH A TROUGH AXIS THAT STEEPENS OVER THE APPALACHIANS AROUND TUE NIGHT...THEN FLATTENS AS THE TROUGH LOSES AMPLITUDE BY THU. SURFACE FEATURES SHOW WEAK HIGH PRESSURE DRIFTING ACROSS THE AREA SUN NGT AND MON AHEAD OF A COLD FRONT MON NIGHT THAT USHERS ANOTHER ARCTIC AIRMASS SOUTHEASTWARD OUT OF THE NORTHERN PLAINS. THE OVERNIGHT GFS SHOWS A WEAK LOW FORMATION IN THE LEE OF THE APPALACHIANS WITH THE COLD FRONT LATE MON... SUGGESTING SOME MOISTURE CONVERGENCE IN LOWER TO MID LEVELS. OTHER MODELS DO NOT RESOLVE THIS FEATURE. THE SURFACE LAYER IS EXPECTED TO BE VERY DRY WITH DEW POINTS OF 10-15 DEGREES AND CHANCES OF PRECIPITATION HITTING THE GROUND REMAIN LESS THAN 15 PERCENT IN THE RAH CWA. TEMPERATURES DROP TO BETWEEN 10 AND 20 DEGREES BELOW NORMAL FOLLOWING THE ARCTIC COLD FRONT FOR TUE AND WED MODERATING BUT STILL BELOW NORMAL ON THU.

&&

.PREV DISCUSSION... /ISSUED 312 AM EST THU FEB 1 2007/

SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... TODAY THROUGH FRIDAY... INTERESTING AND SOMEWHAT TRICKY FORECAST FOR THE NEXT 24 HOURS OVER A LARGE PORTION OF CENTRAL NORTH CAROLINA. MID/HIGH LEVEL CLOUDS SPREADING INTO AREA RESULTING IN TEMPERATURES BOUNCING AROUND SHOWING RISES WHICH MAKES FORECAST ALL THE MORE TRICKY. BUT DEWPOINTS ARE QUITE LOW...STILL SINGLE DIGITS IN NORTHWEST BUT A SLIGHT RISE OVER SOUTH/SOUTHWEST SECTIONS. HOWEVER EXPECT TEMPERATURES TO FALL ONCE PRECIP STARTS. ONSET TIMING AND QPF AMOUNTS ARE THE KEY FACTORS. PRECIPITATION CURRENTLY OVER DEEP SOUTH HANDLED QUITE WELL BY GFS. LATEST RADAR TRENDS SHOW AREA ADVANCING NORTHEAST/EAST FAIRLY QUICKLY. HEAVIER MIX PRECIP CURRENTLY INTO NORTH AND NORTH CENTRAL GEORGIA WITH SOME LIGHTER ECHOES ALOFT NOW OVER CENTRAL CWA. SOME DIFFERENCES EXIST BETWEEN NAM/GFS WHILE THERE ARE SIMILARITIES. NAM IS THE COLDEST AND WETTEST. NAM BRINGS CORE OF HIGHEST PRECIP ACROSS THE CWA WHILE GFS MOVES ACROSS MAINLY SOUTHERN SECTIONS. ALSO NAM HAS MORE PRONOUNCED INSITU WEDGE AND PROFILES FOR GSO/RDU BELOW FREEZING THROUGH 18Z INDICATING A LONGER PERIOD OF SNOW. GFS WEAKER ON INSITU WEDGE AND PROFILES INDICATE PRECIP TRANSITIONING OVER SLEET/FREEZING RAIN BY THE AFTERNOON. TOUGH CALL AS GFS HAS BEEN FAIRLY CONSISTENT AND PERFORMANCE GOOD SO FAR THIS WINTER. GFS PARTIALS ARE MORE IN LINE WITH LATEST GSO RAOB (06Z). 06Z GSO SOUNDING SHOWING QUITE A BIT OF MID LEVEL DRY AIR. PER GFS GOOD ISENTROPIC LIFT COMMENCES OVER CWA AT 12Z WHILE NAM FURTHER SOUTH AND SOUTHWEST. BOTH NAM/GFS SHOWING TWO ROUNDS OF PRECIP MOVING ACROSS THE AREA...ONE DURING THE DAY...THEN ANOTHER WITH SECOND WAVE 00Z-06Z. OVERALL WILL LEAN TOWARD GFS WITH MODIFICATION. WILL HOLD ON TO ALL SNOW LONGER IN NORTHWEST PIEDMONT. ALSO SLOWER TREND ON TRANSITION OF PRECIP IN EASTERN PIEDMONT TO ALL RAIN. ADDITIONALLY WILL ADJUST TEMPERATURE TRENDS TO KEEP COLDER THROUGH 00Z. FOR FRIDAY WILL KEEP DRIZZLE MENTIONED THROUGH MID MORNING. --RA

FRIDAY NIGHT THROUGH SATURDAY NIGHT... AT THIS POINT WILL CONTINUE CURRENT FORECAST TREND. DRY AND COLD.

LONG TERM /SUNDAY THROUGH WEDNESDAY/... BROAD UPPER LEVEL TROUGH REMAIN ANCHORED OVER THE AREA THROUGH THE PERIOD TO REINFORCE COLD AIR OVER THE AREA. AT THE SURFACE HIGH PRESSURE BUILDS OVER THE AREA SUNDAY. SUNDAY NIGHT...A BOUNDARY DEVELOPS ALONG THE VIRGINIA/NORTH CAROLINA BORDER AND EXTENDS WEST AND SOUTHWEST TO TENNESSEE...THEN TO A LOW OVER EASTERN TEXAS. THERE IS SOME MOISTURE AND WEAK UPPER SUPPORT ASSOCIATED WITH THIS FEATURE ..HOWEVER WILL LEAVE FORECAST DRY AT THE PRESENT TIME. THIS SYSTEM WILL BE PUSHED TO THE SOUTHEAST LATE MONDAY AND EARLY TUESDAY AS ARCTIC HIGH PRESSURE BUILDS OVER THE AREA...AND REMAINS OVER THE REGION THROUGH WEDNESDAY. THE RESULT OF THIS ARCTIC AIRMASS WILL BE BELOW TO MUCH BELOW NORMAL TEMPERATURES. -RHJ

AVIATION /07Z-06Z/... ALTOCUMULUS BEGINNING TO MOVE INTO THE FOOTHILLS AT THIS TIME. CLOUDS WILL LOWER OVERNIGHT AND LIKELY DROP BELOW VFR A COUPLE OF HOURS AFTER SUNRISE AT THE TAF LOCATIONS. CEILINGS BELOW 1000 FEET ONCE PRECIPITATION BEGINS WITH MVFR VISIBILITIES IN GENERAL. CEILINGS BELOW 600 FEET MOST OF THE AFTERNOON AND INTO THE NIGHT.

ALL TAF SITES EXPECTING SOME NON-LIQUID PRECIPITATION THURSDAY WITH FAYETTEVILLE HAVING THE LEAST IMPACT AND SHORTEST DURATION...AND GREENSBORO AND WINSTON-SALEM MOST IMPACTED BY WINTER WEATHER. ACCUMULATING SNOW THURSDAY MORNING WILL MIX WITH SLEET AND CHANGE TO FREEZING RAIN IN THE AFTERNOON. LESSER AMOUNTS OF SNOW AND SLEET AS ONE MOVES EAST BUT FREEZING RAIN WILL BE A CONCERN. -RLH/VINCENT

&&

.RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ078-085- 086-088-089.

WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR NCZ007>010- 021>025-038>040-073-074.

WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ011- 026>028-041>043-075>077-083-084.

&&

$$

SHORT TERM...CBL

.SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LARGE TROUGH DOMINATES CENTRAL CANADA AND NORTH CENTRAL CONUS...WITH A SHORT WAVE PRESSING INTO NEW ENGLAND...AS THE NEXT WAVE ROTATES INTO THE MIDWEST. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 175-220KT SOUTHWESTERLY JET EXTENDS FROM THE PLAINS THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A COLD FRONT FROM A 991MB OCCLUDED CYCLONE IN WESTERN QUEBEC SOUTH THROUGH THE MID ATLANTIC. A TROUGH WAS NOTED IN THE LEE OF THE APPALACHIANS WITH A 1026MB ANTICYCLONE ACROSS EASTERN TEXAS. THE NEXT COLD FRONT WAS SLICING THROUGH THE UPPER MIDWEST.

UPSLOPE SNOW SHOWERS ARE QUICKLY DECAYING EARLY THIS MORNING AS ANTICYCLONIC FLOW BUILDS IN FROM THE OHIO VALLEY. A FEW AREAS OF FLURRIES EAST TO THE WESTERN WASHINGTON SUBURBS WILL BE VERY SHORT LIVED.

COLD/DRY ADVECTION ALONG WITH DECENT DOWNSLOPE COMPONENT WILL CONTINUE TO ERODE LOW LEVEL MOISTURE AND PROVIDE A SUNNY DAY EAST OF THE MOUNTAINS. GRADIENT BEHIND THE LAST COLD FRONT WILL STILL SUPPORT WIND GUSTS AS MIXING DEEPENS DURING THE AFTERNOON. WENT BELOW MOS GUIDANCE FOR HIGH TEMPERATURES BASED ON RECENT PERFORMANCE AND COLD ADVECTION.

ANOTHER COLD FRONT PRESSES THROUGH FROM THE OHIO VALLEY THIS EVENING...SHARPENING THE GRADIENT AND REINVIGORATING COLD ADVECTION. WIND GUSTS MAY BE AS HIGH AS 40 MPH IN THE HIGHER TERRAIN...PROMPTING A WIND CHILL ADVISORY ACROSS MUCH OF THE WEST VIRGINIA AND MARYLAND PAN HANDLE REGION. WIND CHILLS DIP INTO THE SINGLE DIGITS EAST TO THE CHESAPEAKE BAY.

PASSAGE OF THE NEXT SHORT WAVE INTO THE EASTERN GREAT LAKES THIS EVENING IS EXPECTED TO BRING SCATTERED CLOUDS TRAPPED UNDER THE SUBSIDENCE INVERSION AND TO RE-INITIATE UPSLOPE SNOW SHOWERS IN THE MOUNTAINS.

&&

.AVIATION... DOWNSLOPE FLOW HAS SCOURED OUT MOISTURE EAST OF THE MOUNTAINS. WINDS WILL REMAIN GUSTY THROUGH THE TAF CYCLE...BACKING THIS EVENING AHEAD OF THE NEXT COLD FRONT...AND VEERING OVERNIGHT AS THE FRONTAL BOUNDARY PUSHES THROUGH. THERE COULD BE SOME MOISTURE TRAPPED UNDER THE SUBSIDENCE INVERSION THIS EVENING AS THE NEXT WAVE MOVES ACROSS THE EASTERN GREAT LAKES.

&&

.MARINE... SMALL CRAFT ADVISORY IS IN EFFECT.

00Z ETA/GFS MOS AT THOMAS POINT INDICATES SUSTAINED WINDS WILL INCREASE FROM 15KT TO 20KT BEGINNING THIS AFTERNOON. 00Z PROXIMITY NAM/GFS BUFKIT FORECAST SOUNDINGS INDICATE WIND GUST POTENTIAL OF 25KT THIS AFTERNOON...AND UP TO 30KT FOR A PERIOD TONIGHT.

SCA WINDS WILL CONTINUE THROUGH SUN AFTERNOON FOR THE MARINE WATERS UNDER STRONG CAA.

A BRIEF RESPITE IN SCA WINDS IS LIKELY SUN NGT AND MON...BUT EXPECT RENEWED SCA WINDS LATE MON THROUGH MIDWEEK AS CAA ENSUES.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A HALF FOOT TO A FOOT ABOVE ASTRONOMICAL PREDICTIONS. THE LUNAR CYCLE IS AT FULL MOON (99% FULL).

THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM WHICH HAD A GOOD HANDLE ON OBSERVED DEPARTURES INDICATES DEPARTURES WILL DIMINISH THROUGH THE AFTERNOON...BUT STILL REMAIN A BIT ABOVE ASTRONOMICAL PREDICTIONS. THE NOAA EXTRATROPICAL SURGE MODEL DID NOT CAPTURE OBSERVED DEPARTURES.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY...

COLDEST AIRMASS OVERHEAD SUNDAY THROUGH MONDAY NGT ACROSS OUR AREA. HAVE UNDERCUT MOS FCST BETWEEN 1-2 CATEGORIES DURING THAT TIMEFRAME BASED ON THE SNOWPACK OUT WEST AND THE FACT THAT CLIMO PROBABLY HOLDING MOS PREDICTIONS BACK FROM THE REALISTIC COLDER VALUES. WILL ALSO CONTINUE TO MENTION HIGH CHCS FOR SN SHWRS ALONG AND W OF THE ALLEG FRONT DURING SUNDAY THROUGH MON NGT WITH GOOD WIND TRAJECTORIES AND DELTA T VALUES.

SLIGHT MODERATION IN TEMPS BUT STILL BELOW NORMS TUE-WED. 00Z GFS IS BRINGING A CLIPPER ESE INTO THE MID ATLC LATE WED INTO THU AND SQUEEZING OUT ALMOST 0.10 INCH QPF WITH THIS SYSTEM ACROSS MUCH OF OUR AREA. WILL INTRODUCE LOW CHC (20-30 POP) ACROSS THE NW HALF OF THE CWFA WITH THIS SYSTEM. 00Z MEX POPS AROUND 50 DURING THIS PERIOD AT MOST SITES. MEDIUM RANGE ENSEMBLES NOT AS GUNG HO ON THE PTNL FOR QPF WITH THIS FEATURE...PARTIALLY BECAUSE YOU GET A 0.10 INCH POP FORECAST VERSUS THE 0.01 INCH WITH THE MEX MOS. 00Z ECMWF IS FASTER WITH THIS FEATURE AND SEEMS TO BE AS STRONG AS THE 00Z GFS RUN. SREF PLUME CHARTS SHOWING AN UPSWING IN SNOW CHCS IN EASTERN OHIO ON THE 7TH IN CONJUNCTION WITH THE CLIPPER SO AN EXTRAPOLATION TO THE 8TH WOULD SUPPORT A CHC OF SNOW AT LEAST IN OUR NW ZONES.

WHETHER OR NOT WE END UP GETTING ANY SNOW WITH THIS NEXT FEATURE IS DEBATABLE...HWVR IT SEEMS LIKELY A REINFORCING SHOT OF ARCTIC AIR WILL ONCE AGAIN BUILD ACROSS OUR REGION WED-THU WITH TEMPS REMAINING BELOW NORMAL THROUGH THE END OF THE WORK WEEK.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 12 PM EST SUNDAY FOR MDZ003-501-502.

VA...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 12 PM EST SUNDAY FOR VAZ021.

WV...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 12 PM EST SUNDAY FOR WVZ050-051-054-055-501>504.

MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST SUNDAY FOR ANZ530>537.

&&

$$

SHORT TERM/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.SHORT TERM /TODAY THROUGH MONDAY/... EXPECT A FEW FLURRIES THIS MORNING ACROSS THE NORTHERN MOUNTAINS OF NORTH CAROLINA. AIRMASS DRIES OUT THIS AFTERNOON TO THE POINT WHERE FLURRIES SHOULD END. WINDY CONDITIONS WILL PREVAIL ACROSS THE NC MOUNTAINS...AND A LAKE WIND ADVISORY WILL BE NEEDED THERE. I/M JUST GOING BREEZY FOR NOW ACROSS THE UPSTATE AND NE GA...BUT DEPENDING ON THE DEPTH OF THE MIXING...A FEW HOURS OF WINDY CONDITIONS ARE QUITE POSSIBLE IN THESE AREAS BY MID AFTERNOON.

LATE TONIGHT A WEAKENING SHORT WAVE WILL APPROACH THE NC MOUNTAINS. 1000-500MB LAYER RH/S INCREASE TO OVER 70 PERCENT ALONG THE TN LINE BETWEEN 9 AND 12 UTC. WHILE THE LOW LEVEL FLOW IS OUT OF THE WEST...WHICH IS NOT OPTIMAL FOR UPSLOPE SNOW SHOWERS...THE WINDS ARE FAIRLY STRONG AT 30 TO 40 KTS. WITH H8 TEMPS AROUND -10 DEG C...THIS SHOULD BE ADEQUATE FOR SNOW SHOWERS FROM MADISON CO NORTHWARD. WENT ON THE COOL SIDE OF MOS TODAY AND TONIGHT.

SNOW SHOWERS WILL LINGER ALONG THE TENN BORDER SUN MORNING...BUT MOISTURE IS EXPECTED TO DIMINISH BY EARLY PM. THIS WILL GIVE WAY TO A DRY BUT SEASONABLY COOL END TO THE WEEKEND.

A STRONG SW TROUGH DIVING OUT OF THE UPPER MIDWEST WILL DEEPEN THE EASTERN TROUGH EARLY NEXT WEEK...SENDING A REINFORCING SHOT OF COLD AIR INTO THE REGION BY EARLY MONDAY. AS A RESULT...MONDAY/S MAX TEMPS WILL LIKELY RANGE FROM THE LOW TEENS IN THE HIGHER ELEVATIONS...TO THE MID AND UPPER 20S IN THE VALLEYS...TO THE MID AND UPPER 30S ACROSS MOST OF THE PIEDMONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... EASTERN LONG WAVE TROUGH WILL CONTINUE TO DOMINATE THE WEATHER THROUGH AT LEAST MID-WEEK. THIS WILL RESULT IN A MOSTLY DRY FORECAST THROUGH THE PERIOD. THE MAIN STORY WILL BE THE COLD...AS TEMPS SHOULD REMAIN BELOW...EVEN WELL BELOW NORMAL THROUGH MID-WEEK... WHEN THE LARGE SCALE FLOW WILL TAKE ON A MORE ZONAL CONFIGURATION ACROSS THE EASTERN STATES. HOWEVER...ANOTHER STRONG SW TROUGH DIVING OUT OF THE UPPER MIDWEST WILL LIKELY SEND ANOTHER SHOT OF COLD AIR INTO THE REGION LATE NEXT WEEK.

&&

.AVIATION /07Z-06Z/... WITH A MUCH DRIER AIRMASS WORKING INTO THE REGION...AND WITH MANY TAF SITES REMAINING MIXED THROUGH SUNRISE...DON/T SEE ANY FOG OR STRATUS CONCERNS THIS MORNING. WINDS WILL GRADUALLY INCREASE INTO THE EARLY AFTERNOON HOURS OUT OF THE WSW. THERE WILL BE DEEP MIXING THIS AFTERNOON...AND GUSTS INTO THE MID 20KT RANGE ARE POSSIBLE JUST ABOUT ANYWHERE...BUT ESPECIALLY ACROSS THE UPSTATE. AT KAVL WINDS WILL BE MORE NORTHWESTERLY...BUT AS MIXING DEEPENS DURING THE AFTERNOON HOURS...WOULDN/T BE SURPRISED TO SEE THEM TURN OUT OF THE WEST AT TIMES. THIS WILL MAKE FOR QUITE A BIT OF LOW LEVEL TURBULENCE...SOMETHING SMALLER AIRCRAFT WILL NEED TO BE WARY OF.

&&

.FIRE WEATHER... DEWPOINTS SHOULD MIX OUT INTO THE SINGLE DIGITS IN THE NORTH CAROLINA ZONES THIS AFTERNOON. WITH A WESTERLY DOWNSLOPE FLOW...DEWPOINTS COULD BECOME ESPECIALLY LOW ACROSS THE FRENCH BROAD VALLEY AND THE NC FOOTHILLS...WITH RH/S FALLING WELL INTO THE TEENS BY LATE AFTERNOON. ELSEWHERE...RH/S WILL STILL FALL AT LEAST INTO THE L-M20S. SO...ACROSS THE MOUNTAINS...THE UPSTATE AND NE GA THERE IS A GOOD CHANCE OF MEETING METEOROLOGICAL RED FLAG CRITERIA. HOWEVER...CALLS TO LAND MANAGEMENT AGENCIES YESTERDAY REVEALED THAT FUEL MOISTURE IS VERY HIGH...SO THE FIRE DANGER IS NOT HIGH ENOUGH TO WARRANT A RED FLAG WARNING.

&&

.GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...LAKE WIND ADVISORY FOR ALL MOUNTAIN ZONES. SC...NONE. &&

$$

SHORT TERM...MCAVOY/LANE LONG TERM...LANE AVIATION/FIRE WEATHER...MCAVOY

.SHORT TERM...BIGGEST CHALLENGE NEXT 24 HOURS WILL BE TEMPERATURE FCST. GUSTY AND ERRATIC CHINOOK WINDS WILL PLAY HAVOC WITH THE TEMPERATURE FIELD...ESPLY FM THE FOOTHILLS EASTWARD ACROSS THE I-25 URBAN CORRIDOR AND ADJACENT AREAS OF WELD...ERN ADAMS...ERN ARAPAHOE AND ELBERT COUNTIES. MODEL TEMPERATURE GUIDANCE INDICATING MAX TEMPERATURES TODAY IN THE 30S ALONG THE FRONT RANGE...BUT NO DOUBT WITH THE SPORADIC NATURE OF CHINOOK WINDS...MAY SEE A SPAN OF 10-15 DEGS WEST-TO-EAST ACROSS THE CORRIDOR. AT ANY EVENT...THE WARMUP IS UNDERWAY. 700 MB TEMP OF -12C NOW OVER DEN AS PER LOCAL ACARS OBS PROG BY WRF AND GFS TO WARM TO AROUND -4C BY 12Z/SUNDAY. WARMUP IN AND NEAR THE FRONT RANGE ALSO ATTRIBUTED TO STG AND GUSTY W-NWLY CHINOOK WINDS. WINDS NOT YET BLOWING AT LOWER ELEVATIONS...BUT OVER HIGHER ELEVATIONS OF THE FRONT RANGE WIND GUSTING IN THE 40-60 MPH IN THE PAST COUPLE HRS WITH A GUST TO 77 MPH PAST HOUR ATOP BERTHOUD PASS. SEVERE BLOWING AND DRIFTING SNOW HAS KEPT LOVELAND PASS CLOSED OVERNIGHT. AT THIS TIME BELIEVE WIDESPREAD WIND SPEEDS NOT EXPECTED TO REACH HIGH WIND CRITERIA BUT NO DOUBT SOME AREAS WILL SEE OCCASIONAL GUSTS MEETING THIS CRITERIA.

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

LONG TERM...STRONG NORTHWEST FLOW ALOFT WITH CROSS MOUNTAIN COMPONENT 40-45 KNOTS AND MOUNTAIN TOP STABLE LAYER WILL CONTINUE TO BRING STRONG GUSTY WINDS TO THE FRONT RANGE SUNDAY MORNING. HOWEVER...WINDS ARE EXPECTED TO WEAKEN BY AFTERNOON AS MID LEVEL FLOW RELAXES TO AROUND 30 KNOTS. CANT RULE OUT LIGHT SNOW SHOWERS IN THE MOUNTAINS AS ANOTHER SURGE OF MID LEVEL MOISTURE PROGGED INTO THE AREA VIA DISSIPATING SHORT WAVE CAUGHT UP IN NORTHWEST FLOW ALOFT. OTHERWISE...TEMPERATURES WILL CONTINUE TO MODERATE WITH WARMING MID LEVEL TEMPERATURES AND DOWNSLOPE COMPONENT...ESPECIALLY NEAR THE FRONT RANGE WHERE EFFECTS OF SNOW COVER ARE MINIMIZED BY THE DOWNSLOPE.

EVEN MORE WARMING EXPECTED MONDAY AND TUESDAY AS MID LEVEL TEMPERATURES CONTINUE TO WARM. AT THIS TIME...DONT SEE ANY SURGE IN NORTHWEST FLOW ALOFT TO BE STRONG ENOUGH TO PUSH BACK AGAINST THE FRONT RANGE...SO WILL CONTINUE TREND OF WARMING THE FORECAST FOR THE I-25 URBAN CORRIDOR. EXPECT QUITE A FEW 50S BY MONDAY AND ESPECIALLY TUESDAY AS 700 MB TEMPS ARE PROGGED TO GET AS HIGH AS +6C BY TUESDAY AFTERNOON. COULDNT EVEN RULE OUT SOME LOWER 60S IF DOWNSLOPE COMPONENT IS STRONG ENOUGH. SPRING MUST BE COMING. FARTHER EAST ACROSS THE PLAINS...SNOW COVER WILL CONTINUE TO HAVE MORE IMPACT ON HIGH TEMPERATURES SO WILL HOLD FAST WITH A MORE CONSERVATIVE APPROACH TO DAYTIME HIGHS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...BLOWING SNOW ADVISORY TODAY AND TONIGHT FRONT RANGE MOUNTAINS AND FOOTHILLS...ZONES 33>36.

&&

$$

BAKER/BARJENBRUCH

.SHORT TERM /REST OF TODAY/... DRY HIGH PRESSURE RIDGING UP FROM THE DEEP SOUTH WILL REMAIN IN PLACE TODAY...BUT WITH A WEAK LEE TROUGH EAST OF MTNS. THE SFC RIDGE WILL GET SUPPRESSED SOUTH BY LATE DAY AS A COLD FRONT MOVES THROUGH THE OHIO VALLEY THIS AFTERNOON UNDER THE BROAD AND DEEP UPPER TROUGH. BREEZY TO WINDY CONDITIONS ARE ANTICIPATED THROUGH THE AFTERNOON...WITH 850 MB FLOW REACHING 35 TO 40 KT ACROSS THE NRN TIER LATE ALONG WITH WEAK COLD ADVECTION. WILL LEAVE THE CURRENT LAKE WIND ADVISORY IN PLACE. THE ONLY CLOUDS TO SPEAK OF THIS AFTERNOON WILL BE SCATTERED UPSLOPE INDUCED CLOUDS IN THE WRN MTNS AND SCATTERED CIRRUS UNDER THE PIEDMONT JET AXIS. WILL TRIM TEMPERATURES A DEGREE OR SO GIVEN A SLOW START NEXT TO GUIDANCE AND VERY COOL THICKNESSES ON THE MORNING SOUNDINGS.

&&

.FIRE WEATHER... COORDINATION WITH FIRE WEATHER USERS TODAY AND YESTERDAY HAS INDICATED THAT RED FLAG CRITERIA ARE NOT EXPECTED TO BE MET DUE TO WET FUELS. HOWEVER...LOW RH AND BREEZY/WINDY CONDITIONS WILL LEAD TO RAPID FUEL DRYING THROUGH MONDAY. A FIRE DANGER STATEMENT FOR NORTH CAROLINA COULD BE NEEDED AT SOME POINT THIS WEEKEND...HOWEVER WILL JUST HEADLINE WIND/RH CONCERNS FOR NOW.

&&

.PREV DISCUSSION... /ISSUED 221 AM EST SAT FEB 3 2007/

SHORT TERM /TODAY THROUGH MONDAY/... EXPECT A FEW FLURRIES THIS MORNING ACROSS THE NORTHERN MOUNTAINS OF NORTH CAROLINA. AIRMASS DRIES OUT THIS AFTERNOON TO THE POINT WHERE FLURRIES SHOULD END. WINDY CONDITIONS WILL PREVAIL ACROSS THE NC MOUNTAINS...AND A LAKE WIND ADVISORY WILL BE NEEDED THERE. I/M JUST GOING BREEZY FOR NOW ACROSS THE UPSTATE AND NE GA...BUT DEPENDING ON THE DEPTH OF THE MIXING...A FEW HOURS OF WINDY CONDITIONS ARE QUITE POSSIBLE IN THESE AREAS BY MID AFTERNOON.

LATE TONIGHT A WEAKENING SHORT WAVE WILL APPROACH THE NC MOUNTAINS. 1000-500MB LAYER RH/S INCREASE TO OVER 70 PERCENT ALONG THE TN LINE BETWEEN 9 AND 12 UTC. WHILE THE LOW LEVEL FLOW IS OUT OF THE WEST...WHICH IS NOT OPTIMAL FOR UPSLOPE SNOW SHOWERS...THE WINDS ARE FAIRLY STRONG AT 30 TO 40 KTS. WITH H8 TEMPS AROUND -10 DEG C...THIS SHOULD BE ADEQUATE FOR SNOW SHOWERS FROM MADISON CO NORTHWARD. WENT ON THE COOL SIDE OF MOS TODAY AND TONIGHT.

SNOW SHOWERS WILL LINGER ALONG THE TENN BORDER SUN MORNING...BUT MOISTURE IS EXPECTED TO DIMINISH BY EARLY PM. THIS WILL GIVE WAY TO A DRY BUT SEASONABLY COOL END TO THE WEEKEND.

A STRONG SW TROUGH DIVING OUT OF THE UPPER MIDWEST WILL DEEPEN THE EASTERN TROUGH EARLY NEXT WEEK...SENDING A REINFORCING SHOT OF COLD AIR INTO THE REGION BY EARLY MONDAY. AS A RESULT...MONDAY/S MAX TEMPS WILL LIKELY RANGE FROM THE LOW TEENS IN THE HIGHER ELEVATIONS...TO THE MID AND UPPER 20S IN THE VALLEYS...TO THE MID AND UPPER 30S ACROSS MOST OF THE PIEDMONT.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... EASTERN LONG WAVE TROUGH WILL CONTINUE TO DOMINATE THE WEATHER THROUGH AT LEAST MID-WEEK. THIS WILL RESULT IN A MOSTLY DRY FORECAST THROUGH THE PERIOD. THE MAIN STORY WILL BE THE COLD...AS TEMPS SHOULD REMAIN BELOW...EVEN WELL BELOW NORMAL THROUGH MID-WEEK... WHEN THE LARGE SCALE FLOW WILL TAKE ON A MORE ZONAL CONFIGURATION ACROSS THE EASTERN STATES. HOWEVER...ANOTHER STRONG SW TROUGH DIVING OUT OF THE UPPER MIDWEST WILL LIKELY SEND ANOTHER SHOT OF COLD AIR INTO THE REGION LATE NEXT WEEK.

AVIATION /07Z-06Z/... WITH A MUCH DRIER AIRMASS WORKING INTO THE REGION...AND WITH MANY TAF SITES REMAINING MIXED THROUGH SUNRISE...DON/T SEE ANY FOG OR STRATUS CONCERNS THIS MORNING. WINDS WILL GRADUALLY INCREASE INTO THE EARLY AFTERNOON HOURS OUT OF THE WSW. THERE WILL BE DEEP MIXING THIS AFTERNOON...AND GUSTS INTO THE MID 20KT RANGE ARE POSSIBLE JUST ABOUT ANYWHERE...BUT ESPECIALLY ACROSS THE UPSTATE. AT KAVL WINDS WILL BE MORE NORTHWESTERLY...BUT AS MIXING DEEPENS DURING THE AFTERNOON HOURS...WOULDN/T BE SURPRISED TO SEE THEM TURN OUT OF THE WEST AT TIMES. THIS WILL MAKE FOR QUITE A BIT OF LOW LEVEL TURBULENCE...SOMETHING SMALLER AIRCRAFT WILL NEED TO BE WARY OF.

FIRE WEATHER... DEWPOINTS SHOULD MIX OUT INTO THE SINGLE DIGITS IN THE NORTH CAROLINA ZONES THIS AFTERNOON. WITH A WESTERLY DOWNSLOPE FLOW...DEWPOINTS COULD BECOME ESPECIALLY LOW ACROSS THE FRENCH BROAD VALLEY AND THE NC FOOTHILLS...WITH RH/S FALLING WELL INTO THE TEENS BY LATE AFTERNOON. ELSEWHERE...RH/S WILL STILL FALL AT LEAST INTO THE L-M20S. SO...ACROSS THE MOUNTAINS...THE UPSTATE AND NE GA THERE IS A GOOD CHANCE OF MEETING METEOROLOGICAL RED FLAG CRITERIA. HOWEVER...CALLS TO LAND MANAGEMENT AGENCIES YESTERDAY REVEALED THAT FUEL MOISTURE IS VERY HIGH...SO THE FIRE DANGER IS NOT HIGH ENOUGH TO WARRANT A RED FLAG WARNING.

&&

.GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...LAKE WIND ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR NCZ033- 048>053-058-059-062>065-501-503-505-507-509.

SC...NONE. &&

$$

SHORT TERM...HG FIRE WEATHER...HG

.AVIATION... VFR CONDITIONS FOR BOTH KDFW AND KACT TRACONS TODAY AND TONIGHT. SURFACE HIGH PRESSURE IS CENTER OVER NEAR KCLL THIS MORNING AND WILL SLIDE TO THE TEXAS COAST THIS AFTERNOON...THEN INTO THE SOUTHERN ALABAMA BY 12Z SUNDAY. WINDS WILL BE SOUTH TO SOUTHWEST 8-14 KNOTS TODAY...THEN WEAKENING TO 4-7 KNOTS OVERNIGHT. KACT WILL SEE SOME SCATTERED MID/HIGH LEVEL CLOUDS AND A SIMILAR WIND TREND AS WELL.

SUB-FREEZING TEMPERATURES WILL PERSIST UNTIL MID MORNING. THIS WILL LIKELY RESULT IN A HEAVY FROST COATING AIRCRAFT PARKED OVERNIGHT. 75

&&

.PREV DISCUSSION... / ISSUED 222 AM CST SAT FEB 3 2007 / STARTING OFF THE DAY WITH A CHILLY MORNING IN DRY/POLAR AIRMASS WITH LIGHT WINDS. MORNING LOWS THE COLDEST WE`VE SEEN IN AWHILE THIS WINTER SEASON WITH 20S AREAWIDE...WITH POSSIBLE UPPER TEENS ACROSS SHELTERED AREAS OF THE WRN/NRN COUNTIES. SHOULD BE SOME FROST AND POSSIBLE SHALLOW...FREEZING GROUND FOG...BUT NOTHING TOO BAD OR WIDESPREAD. MAY ADD PATCHY FOG IN FCST EARLY THIS MORNING.

OTHERWISE...THE WARMING/MODIFICATION PROCESS BEGINS TODAY AND INTO MONDAY...AS CANADIAN MID LVL POLAR VORTEX OVER WRN ONTARIO SHIFTS EWD OVER THE CANADIAN MARITIMES DURING THIS TIME...AND MID LVL RIDGE AMPLIFIES OVER THE WRN CONUS. MEANWHILE...LOW LVL WAA WILL GET GOING AS SLY COMPONENT BEGINS. TEMPERED WARM UP MORE TOWARD LOW GFS ENSEMBLE MOS NUMBERS TODAY WITH A LARGE TEMP CONTRAST FROM NE-SW (COLDER...WARMER RESPECTIVELY)...THEN WARM IT UP ANOTHER COUPLE OF CATEGORIES INTO SUN. JUST IN TIME FOR YOU WEEKEND ENTHUSIASTS. A BACK-DOOR COLD FRONT WILL ENTER FROM THE NE ON MONDAY AND HAVE LOWERED TEMPS ACROSS THE NE 1/2 OF N TX WITH THIS IN MIND...BUT NOT TOO TERRIBLY COLD WITH TEMPS 45-50 NORTH ...IN THE 50S TO NEAR 60 SOUTH. MID LVL S/W DROPS OUT OF ROCKIES AND OVER TX MON AFTN/NIGHT ...BUT FEEL LOW LVL MSTR IS TOO SHALLOW WITH VERY DRY MID LVL AIR FOR ANY RAIN CHANCES. AIRMASS WILL MOISTEN/WARM TUES/WED AS MID LVL RIDGE EXPANDS OVERHEAD AND NIGHTLY LLJ TRANSPORTS SOME MODIFIED MSTR NWD. NEAR SEASONABLE TEMPS FOR EARLY FEBRUARY EXPECTED MID WEEK.

SOME CHANGES ARRIVE LATE WEEK AS MID LVL RIDGE WEAKENS AND ERN CONUS POLAR VORTEX RETROGRADES WWD SOME...ALLOW FOR MORE MID LVL ENERGY AND ARRIVAL OF SOME COLD AIR ONCE AGAIN BY THE WEEKEND. TIMING OF FEATURES/QPF/COLDER AIR TOUGH TO ASCERTAIN...SO KEPT THINGS A COLD RAIN AND WENT MIDDLE OF THE ROAD WITH TEMPS...BUT GENERALLY ON THE LOWER END OF THE GFS ENSEMBLE MOS NUMBERS WHICH MATCH UP WELL WITH ECMWF PROJECTION OF PATTERN. IF BACK-DOOR AIRMASS THURS INTO FRI IS COLDER THAN EXPECTED...COULD SEE A FZRA POTENTIAL NEAR IMMEDIATE RED RIVER VALLEY...BUT LAID OFF THAT FOR NOW. EVEN COLDER...SHALLOW AIRMASS ARRIVES NEXT WEEKEND...BUT LEFT ANY PRECIP CHANCES OUT WITH MOISTURE AVAILABILITY IN QUESTION.

&&

.PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 48 33 57 36 50 / 0 0 0 0 0 WACO, TX 52 35 62 40 55 / 0 0 0 0 0 PARIS, TX 44 29 52 31 41 / 0 0 0 0 10 DENTON, TX 48 30 56 32 48 / 0 0 0 0 0 MCKINNEY, TX 47 30 54 33 47 / 0 0 0 0 10 DALLAS, TX 48 35 57 38 51 / 0 0 0 0 0 TERRELL, TX 48 33 56 38 51 / 0 0 0 0 10 CORSICANA, TX 51 34 59 40 54 / 0 0 0 0 10 TEMPLE, TX 55 36 63 42 57 / 0 0 0 0 0

&&

.FWD WATCHES/WARNINGS/ADVISORIES... NONE. &&

$$

/05

.SYNOPSIS...HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL BRING FAIR AND WARMER WEATHER THROUGH EARLY NEXT WEEK WITH NEAR RECORD HIGH TEMPERATURES POSSIBLE SUNDAY AND MONDAY. LOCALLY WINDY THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES AT TIMES. A SERIES OF LOW PRESSURE SYSTEMS WILL BRING MORE CLOUDS AND COOLING WITH CHANCES OF PRECIPITATION DURING THE LATTER PART OF NEXT WEEK.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

.SHORT TERM (TODAY-TUE)...CLEAR SKIES TODAY EXCEPT FOR PATCHY GROUND FOG INLAND THIS MORNING. ACARS SOUNDINGS SHOWED NE WINDS IN THE LOW LEVELS INCREASING TO ABOUT 20 KT AROUND 10 KFT WITH STRONG N WINDS ALOFT. OFFSHORE GRADIENTS WITH ABOUT -5 MB SAN-TPH.

A STRONG HIGH AMPLITUDE RIDGE OF HIGH PRESSURE ALONG THE W COAST WILL SLOWLY SHIFT INLAND SUN AND GRADUALLY WEAKEN MON AND TUE. OFFSHORE FLOW FROM THE N AND NE WILL SHIFT MORE OFFSHORE FROM THE E MON AND WEAKEN TUE. THERE COULD BE LOCAL GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES...BUT WIDESPREAD SUSTAINED ADVISORY STRENGTH WINDS ARE NOT EXPECTED. THE HIGH ALOFT AND OFFSHORE FLOW WILL BRING MUCH WARMER DAYS...ESPECIALLY SUN AND MON WHEN NEAR RECORD MAX TEMPS ARE POSSIBLE. A LITTLE COOLER TUE...MAINLY W OF THE MOUNTAINS. SKIES WILL BE MOSTLY CLEAR EXCEPT FOR A FEW HIGH CLOUDS AT TIMES. THE WARM...DRY OFFSHORE WINDS WILL ALSO INCREASE THE FIRE WEATHER HAZARD.

&&

.LONG TERM (WED-SAT)...HEIGHTS WILL CONTINUE TO LOWER WED AND ONSHORE FLOW WILL RETURN AS AN UPPER LEVEL TROUGH OF LOW PRESSURE APPROACHES FROM THE W. LOOKS LIKE A PATTERN IS SETTING UP FOR A STRONG SRN BRANCH OF FLOW ACROSS THE PAC BRINGING A SERIES OF SHORT WAVES THROUGH SRN CA. THE EXACT TIMING OF THESE FAST MOVING LOW LATITUDE SHORT WAVES IS STILL UNCERTAIN BUT THEY SHOULD EVENTUALLY BRING A CHANCE OF PRECIP. THE CURRENT TIMING INDICATES A WEAK SHORT WAVE WILL BRING A CHANCE OF SHOWERS LATE WED AND THU. SLIGHT CHANCE OF SHOWERS FRI IN MOIST WLY FLOW UNDER A VERY WEAK RIDGE. A STRONGER SYSTEMS COULD BRING MORE PRECIP NEXT WEEKEND.

&&

.AVIATION... WEAK OFFSHORE FLOW WILL BRING VFR CONDITIONS TO ALL AREA AIRPORTS THROUGH SUNDAY WITH A MOSTLY CLEAR SKY AND UNRESTRICTED VISIBILITIES.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC...DVA AVIATION...HORTON

.AVIATION... 1100 AM VFR THROUGH TODAY...NO PROBLEMS EXPECTED. WILL WRITE SOME 3SM BR IN FOR SUNDAY MORNING. WEAK BOUNDARY MOVES INTO AREA OVERNIGHT AND MODEL SOUNDINGS SHOW LOW LEVEL SATURATION WITH VERY LIGHT WINDS. ATMOSPHERE TOO DRY TO SUPPORT DENSE FOG. 84

&&

.DISCUSSION... 1040 AM LIGHT WINDS...CLEAR SKIES...AND LOW DEWPOINTS ALLOWED TEMPERATURES TO FALL INTO THE UPPER TEENS TO MID 20S ACROSS NORTH TEXAS OVERNIGHT. TEMPERATURES ARE WARMING UP QUICKLY...AFTER A VERY COLD START THIS MORNING. AS OF 10 AM...TEMPERATURES HAD WARMED INTO THE MID TO UPPER 30S. SOUTHERLY WINDS OF 10 TO 15 WITH GUSTS TO OVER 20 MPH WILL OCCUR THIS AFTERNOON. THE PREVIOUS FORECAST IS IN PRETTY GOOD SHAPE...AND ONLY MINOR ADJUSTMENTS WERE MADE TO THE FIRST PERIOD FORECAST. #58

&&

.PREV DISCUSSION... /ISSUED 515 AM CST SAT FEB 3 2007/

.PREV AVIATION... VFR CONDITIONS FOR BOTH KDFW AND KACT TRACONS TODAY AND TONIGHT. SURFACE HIGH PRESSURE IS CENTER OVER NEAR KCLL THIS MORNING AND WILL SLIDE TO THE TEXAS COAST THIS AFTERNOON...THEN INTO THE SOUTHERN ALABAMA BY 12Z SUNDAY. WINDS WILL BE SOUTH TO SOUTHWEST 8-14 KNOTS TODAY...THEN WEAKENING TO 4-7 KNOTS OVERNIGHT. KACT WILL SEE SOME SCATTERED MID/HIGH LEVEL CLOUDS AND A SIMILAR WIND TREND AS WELL.

SUB-FREEZING TEMPERATURES WILL PERSIST UNTIL MID MORNING. THIS WILL LIKELY RESULT IN A HEAVY FROST COATING AIRCRAFT PARKED OVERNIGHT. 75

PREV DISCUSSION... / ISSUED 222 AM CST SAT FEB 3 2007 / STARTING OFF THE DAY WITH A CHILLY MORNING IN DRY/POLAR AIRMASS WITH LIGHT WINDS. MORNING LOWS THE COLDEST WE`VE SEEN IN AWHILE THIS WINTER SEASON WITH 20S AREAWIDE...WITH POSSIBLE UPPER TEENS ACROSS SHELTERED AREAS OF THE WRN/NRN COUNTIES. SHOULD BE SOME FROST AND POSSIBLE SHALLOW...FREEZING GROUND FOG...BUT NOTHING TOO BAD OR WIDESPREAD. MAY ADD PATCHY FOG IN FCST EARLY THIS MORNING.

OTHERWISE...THE WARMING/MODIFICATION PROCESS BEGINS TODAY AND INTO MONDAY...AS CANADIAN MID LVL POLAR VORTEX OVER WRN ONTARIO SHIFTS EWD OVER THE CANADIAN MARITIMES DURING THIS TIME...AND MID LVL RIDGE AMPLIFIES OVER THE WRN CONUS. MEANWHILE...LOW LVL WAA WILL GET GOING AS SLY COMPONENT BEGINS. TEMPERED WARM UP MORE TOWARD LOW GFS ENSEMBLE MOS NUMBERS TODAY WITH A LARGE TEMP CONTRAST FROM NE-SW (COLDER...WARMER RESPECTIVELY)...THEN WARM IT UP ANOTHER COUPLE OF CATEGORIES INTO SUN. JUST IN TIME FOR YOU WEEKEND ENTHUSIASTS. A BACK-DOOR COLD FRONT WILL ENTER FROM THE NE ON MONDAY AND HAVE LOWERED TEMPS ACROSS THE NE 1/2 OF N TX WITH THIS IN MIND...BUT NOT TOO TERRIBLY COLD WITH TEMPS 45-50 NORTH ...IN THE 50S TO NEAR 60 SOUTH. MID LVL S/W DROPS OUT OF ROCKIES AND OVER TX MON AFTN/NIGHT ..BUT FEEL LOW LVL MSTR IS TOO SHALLOW WITH VERY DRY MID LVL AIR FOR ANY RAIN CHANCES. AIRMASS WILL MOISTEN/WARM TUES/WED AS MID LVL RIDGE EXPANDS OVERHEAD AND NIGHTLY LLJ TRANSPORTS SOME MODIFIED MSTR NWD. NEAR SEASONABLE TEMPS FOR EARLY FEBRUARY EXPECTED MID WEEK.

SOME CHANGES ARRIVE LATE WEEK AS MID LVL RIDGE WEAKENS AND ERN CONUS POLAR VORTEX RETROGRADES WWD SOME...ALLOW FOR MORE MID LVL ENERGY AND ARRIVAL OF SOME COLD AIR ONCE AGAIN BY THE WEEKEND. TIMING OF FEATURES/QPF/COLDER AIR TOUGH TO ASCERTAIN...SO KEPT THINGS A COLD RAIN AND WENT MIDDLE OF THE ROAD WITH TEMPS...BUT GENERALLY ON THE LOWER END OF THE GFS ENSEMBLE MOS NUMBERS WHICH MATCH UP WELL WITH ECMWF PROJECTION OF PATTERN. IF BACK-DOOR AIRMASS THURS INTO FRI IS COLDER THAN EXPECTED...COULD SEE A FZRA POTENTIAL NEAR IMMEDIATE RED RIVER VALLEY...BUT LAID OFF THAT FOR NOW. EVEN COLDER...SHALLOW AIRMASS ARRIVES NEXT WEEKEND...BUT LEFT ANY PRECIP CHANCES OUT WITH MOISTURE AVAILABILITY IN QUESTION.

&&

.PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 48 33 57 36 49 / 0 0 0 0 0 WACO, TX 52 35 62 40 55 / 0 0 0 0 0 PARIS, TX 44 29 52 31 45 / 0 0 0 0 10 DENTON, TX 48 30 56 32 48 / 0 0 0 0 0 MCKINNEY, TX 47 30 54 33 48 / 0 0 0 0 10 DALLAS, TX 48 35 57 38 50 / 0 0 0 0 0 TERRELL, TX 48 33 56 38 51 / 0 0 0 0 10 CORSICANA, TX 51 34 59 40 53 / 0 0 0 0 10 TEMPLE, TX 55 36 63 42 57 / 0 0 0 0 0

&&

.FWD WATCHES/WARNINGS/ADVISORIES... NONE. &&

$$

84/58

.DISCUSSION... LIGHT WINDS...CLEAR SKIES...AND LOW DEWPOINTS ALLOWED TEMPERATURES TO FALL INTO THE UPPER TEENS TO MID 20S ACROSS NORTH TEXAS OVERNIGHT. TEMPERATURES ARE WARMING UP QUICKLY...AFTER A VERY COLD START THIS MORNING. AS OF 10 AM...TEMPERATURES HAD WARMED INTO THE MID TO UPPER 30S. SOUTHERLY WINDS OF 10 TO 15 WITH GUSTS TO OVER 20 MPH WILL OCCUR THIS AFTERNOON. THE PREVIOUS FORECAST IS IN PRETTY GOOD SHAPE...AND ONLY MINOR ADJUSTMENTS WERE MADE TO THE FIRST PERIOD FORECAST. #58

&&

.PREV DISCUSSION... /ISSUED 515 AM CST SAT FEB 3 2007/

AVIATION... VFR CONDITIONS FOR BOTH KDFW AND KACT TRACONS TODAY AND TONIGHT. SURFACE HIGH PRESSURE IS CENTER OVER NEAR KCLL THIS MORNING AND WILL SLIDE TO THE TEXAS COAST THIS AFTERNOON...THEN INTO THE SOUTHERN ALABAMA BY 12Z SUNDAY. WINDS WILL BE SOUTH TO SOUTHWEST 8-14 KNOTS TODAY...THEN WEAKENING TO 4-7 KNOTS OVERNIGHT. KACT WILL SEE SOME SCATTERED MID/HIGH LEVEL CLOUDS AND A SIMILAR WIND TREND AS WELL.

SUB-FREEZING TEMPERATURES WILL PERSIST UNTIL MID MORNING. THIS WILL LIKELY RESULT IN A HEAVY FROST COATING AIRCRAFT PARKED OVERNIGHT. 75

PREV DISCUSSION... / ISSUED 222 AM CST SAT FEB 3 2007 / STARTING OFF THE DAY WITH A CHILLY MORNING IN DRY/POLAR AIRMASS WITH LIGHT WINDS. MORNING LOWS THE COLDEST WE`VE SEEN IN AWHILE THIS WINTER SEASON WITH 20S AREAWIDE...WITH POSSIBLE UPPER TEENS ACROSS SHELTERED AREAS OF THE WRN/NRN COUNTIES. SHOULD BE SOME FROST AND POSSIBLE SHALLOW...FREEZING GROUND FOG...BUT NOTHING TOO BAD OR WIDESPREAD. MAY ADD PATCHY FOG IN FCST EARLY THIS MORNING.

OTHERWISE...THE WARMING/MODIFICATION PROCESS BEGINS TODAY AND INTO MONDAY...AS CANADIAN MID LVL POLAR VORTEX OVER WRN ONTARIO SHIFTS EWD OVER THE CANADIAN MARITIMES DURING THIS TIME...AND MID LVL RIDGE AMPLIFIES OVER THE WRN CONUS. MEANWHILE...LOW LVL WAA WILL GET GOING AS SLY COMPONENT BEGINS. TEMPERED WARM UP MORE TOWARD LOW GFS ENSEMBLE MOS NUMBERS TODAY WITH A LARGE TEMP CONTRAST FROM NE-SW (COLDER...WARMER RESPECTIVELY)...THEN WARM IT UP ANOTHER COUPLE OF CATEGORIES INTO SUN. JUST IN TIME FOR YOU WEEKEND ENTHUSIASTS. A BACK-DOOR COLD FRONT WILL ENTER FROM THE NE ON MONDAY AND HAVE LOWERED TEMPS ACROSS THE NE 1/2 OF N TX WITH THIS IN MIND...BUT NOT TOO TERRIBLY COLD WITH TEMPS 45-50 NORTH ...IN THE 50S TO NEAR 60 SOUTH. MID LVL S/W DROPS OUT OF ROCKIES AND OVER TX MON AFTN/NIGHT ..BUT FEEL LOW LVL MSTR IS TOO SHALLOW WITH VERY DRY MID LVL AIR FOR ANY RAIN CHANCES. AIRMASS WILL MOISTEN/WARM TUES/WED AS MID LVL RIDGE EXPANDS OVERHEAD AND NIGHTLY LLJ TRANSPORTS SOME MODIFIED MSTR NWD. NEAR SEASONABLE TEMPS FOR EARLY FEBRUARY EXPECTED MID WEEK.

SOME CHANGES ARRIVE LATE WEEK AS MID LVL RIDGE WEAKENS AND ERN CONUS POLAR VORTEX RETROGRADES WWD SOME...ALLOW FOR MORE MID LVL ENERGY AND ARRIVAL OF SOME COLD AIR ONCE AGAIN BY THE WEEKEND. TIMING OF FEATURES/QPF/COLDER AIR TOUGH TO ASCERTAIN...SO KEPT THINGS A COLD RAIN AND WENT MIDDLE OF THE ROAD WITH TEMPS...BUT GENERALLY ON THE LOWER END OF THE GFS ENSEMBLE MOS NUMBERS WHICH MATCH UP WELL WITH ECMWF PROJECTION OF PATTERN. IF BACK-DOOR AIRMASS THURS INTO FRI IS COLDER THAN EXPECTED...COULD SEE A FZRA POTENTIAL NEAR IMMEDIATE RED RIVER VALLEY...BUT LAID OFF THAT FOR NOW. EVEN COLDER...SHALLOW AIRMASS ARRIVES NEXT WEEKEND...BUT LEFT ANY PRECIP CHANCES OUT WITH MOISTURE AVAILABILITY IN QUESTION.

&&

.PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 48 33 57 36 49 / 0 0 0 0 0 WACO, TX 52 35 62 40 55 / 0 0 0 0 0 PARIS, TX 44 29 52 31 45 / 0 0 0 0 10 DENTON, TX 48 30 56 32 48 / 0 0 0 0 0 MCKINNEY, TX 47 30 54 33 48 / 0 0 0 0 10 DALLAS, TX 48 35 57 38 50 / 0 0 0 0 0 TERRELL, TX 48 33 56 38 51 / 0 0 0 0 10 CORSICANA, TX 51 34 59 40 53 / 0 0 0 0 10 TEMPLE, TX 55 36 63 42 57 / 0 0 0 0 0

&&

.FWD WATCHES/WARNINGS/ADVISORIES... NONE. &&

$$

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