Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 01/25/07

.SYNOPSIS...WEAK OFFSHORE FLOW AND HIGH PRESSURE ALOFT WILL CONTINUE MOSTLY CLEAR SKIES WITH WARMER DAYS THROUGH THURSDAY. LOCALLY BREEZY THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES AT TIMES THROUGH THURSDAY. UPPER LEVEL LOW PRESSURE AND ONSHORE FLOW WILL BRING MORE CLOUDS AND COOLER DAYS THIS WEEKEND AND EARLY NEXT WEEK.

&&

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

.SHORT TERM (TODAY-FRI)...CLEAR SKIES TODAY EXCEPT FOR A FEW HIGH CLOUDS. ACARS SOUNDINGS SHOWED WEAK NE WINDS AT OR BELOW 10 KTS IN THE LOW LEVELS AND ONLY 25-30 KT ABOVE 10 KFT. WEAKENING OFFSHORE GRADIENTS WITH ABOUT -4 MB SAN-TPH.

A RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE W COAST WHILE A LOW UNDERCUTS IT AND MEANDERS AROUND OVER NW MEX THROUGH WED. AN UPPER TROUGH MOVES INTO NRN CA AND THE CLOSED LOW OVER MEX BEGINS TO MOVE OFF THE TO E ON THU. THE TROUGH CONTINUES TO SLOWLY MOVE E WITH GRADUALLY LOWERING HEIGHTS LATE THU AND FRI. WEAK OFFSHORE FLOW MAY BRIEFLY REINTENSIFY WED BUT WINDS WILL REMAIN BELOW ADVISORY STRENGTH. TEMPS AT 850 MB INCREASE THROUGH WED...LEVEL OFF THU AND DECREASE A LITTLE FRI. SKIES WILL REMAIN MOSTLY CLEAR THROUGH THU THEN THERE WILL BE INCREASING HIGH CLOUDINESS FRI. MILD DAYS IN MOST AREAS WED...ESPECIALLY W OF THE MOUNTAINS. SLIGHTLY COOLER THU IN THE COASTAL AND VALLEY AREAS AS A STRONGER AFTERNOON SEA BREEZE DEVELOPS. COOLER IN MOST AREAS FRI WITH DECREASING HEIGHTS AND STRONGER ONSHORE FLOW.

THE DRY OFFSHORE FLOW WILL CONTINUE AREAS OF VERY LOW HUMIDITIES THE REMAINDER OF THIS AFTERNOON. IT WILL STILL BE QUITE DRY WED BUT HUMIDITIES SHOULD NOT BE LOW ENOUGH FOR A LONG ENOUGH PERIOD OF TIME FOR RED FLAG CONDITIONS.

.LONG TERM (SAT-TUE)...PROGS CONTINUE IN POOR AGREEMENT ON THE DETAILS BUT GENERALLY INDICATE TROUGHING ALOFT AND ONSHORE FLOW THROUGH THE EXTENDED PERIOD. THIS WILL BRING A RETURN OF MARINE LAYER CLOUDS AND ALSO MORE MID TO HIGH CLOUDINESS. THE COOL UPPER TROUGH AND LIMITED MOISTURE WILL RESULT IN A SLIGHT CHANCE OF PRECIP EARLY NEXT WEEK OVER AND W OF THE MOUNTAINS. COOLER DAYS. RELATIVELY MILD NIGHTS W OF THE MOUNTAINS DUE TO INCREASED CLOUD COVER.

&&

.AVIATION... CLEAR SKIES TONIGHT THROUGH WEDNESDAY. ONLY AVIATION CONCERN IS OCCASIONAL MODERATE TURBULENCE OVER AND TO THE SOUTHWEST OF MOUNTAINS. WINDS BELOW FL035 UNTIL 2000 PST/0400 UTC...WEST TO NORTHWEST 5-10 KNOTS...OTHERWISE WINDS FL0100-FL100 NORTHEAST 10-20 KNOTS TONIGHT BECOMING EAST 10-15 KNOTS AFTER 0700 PST/1500 UTC.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

RED FLAG WARNING UNTIL 6 PM PST THIS AFTERNOON FOR THE MOUNTAINS...INLAND VALLEYS AND ORANGE COUNTY. SEE LAXRFWSGX.

&&

$$

PUBLIC...DVA AVIATION...BALFOUR

DISCUSSION FOR MORNING ZONES/GRIDS... 430 AM CST

DISTURBANCES TO PERIODICALLY DROP SOUTHEAST ACROSS CENTRAL CANADA AS THE UPPER RIDGE CONTINUES TO BUILD ACROSS WESTERN CANADA THROUGH THE WEEKEND. THIS KEEPS REGION SEASONALLY COLD AS CORE OF COLD AIR DROPS ACROSS ONTARIO TO THE LOWER LAKES...ST. LAWRENCE VALLEY AND NEW ENGLAND MID AND LATE WEEK. COLD AIR CURRENTLY OVER THE YKON AND ALASKA ARRIVES SAT AND SAT NIGHT FOLLOWING SHORT WAVE TROF PASSAGE AND CFP.

LATEST IMPULSE IS MOVING ACROSS LAKE MI EARLY THIS MORNING WHILE NEXT IN SERIES IS QUICKLY DROPPING ACROSS MT WITH WAA MID CLOUDS ALREADY SPREADING INTO SW MN AND NW IA. STRATUS/STRATOCU CEILINGS CONTINUE TO CLEAR W TO E ACROSS NW AND W CENTRAL IL AT AROUND 30 KTS AND SHOULD CLEAR THE IN STATE LINE BY AROUND 14Z BUT THE MID CLOUDS WILL BE NOT FAR BEHIND AND WILL BE SPREADING ACROSS THE AREA LATER THIS MORNING AND THROUGH THE AFTERNOON. MODELS INDICATE THAT THE ISENTROPIC LIFT AHEAD OF THE SHORT WAVE WILL SLICE ESE ACROSS NW IL INTO CENTRAL IND DURING THE AFTERNOON...AND THAT ONLY THE FAR SW AND SOITHERN PORTIONS OF THE FA ARE AT RISK OF SEEING MEASURABLE SN FROM LATE AFTERNOON THRU THIS EVE.

ANOTHER SHORT WAVE IS TO DROP SE ON WED BUT FURTHER TO THE E ACROSS WESTERN ONTARIO INTO UPPER GREAT LAKES WITH PRECIP THREAT REMAINING IN WI AND LOWER MI. AS THIS WAVE PASSES BY WED NIGHT THE EDGE OF ANOTHER SHOT OF COLD AIR BRUSHES BY INTO THE CENTRAL LAKES. THIS WITH VEERING SURFACE WINDS MAY BRING LAKE EFFECT SHSN AS FAR WEST AS THE NE CORNER OF PORTER CO. THE LAKE EFFECT MAY PERSIST INTO THU AS THE SURFACE RIDGE BUILDS ACROSS THE UPPER MIDWEST AND UPPER GREAT LAKES KEEPING NNW-NW LOW LEVEL FLOW GOING.

UPPER LOW THAT BREACHES THE TOP OF THE WESTERN UPPER RIDGE IS FORECAST TO MOVE FROM NORTHERN SASK AND ACROSS NORTHERN ONTARIO FRI AND SAT. FLOW BACKS AHEAD OF THE SYSTEM AND BRINGS SOME MODERATION FRI AND FRI NIGHT BEFORE COLD FRONT TRAILING FROM THE ASSOCIATED SURFACE LOW DROPS SE OUT OF THE UPPER MIDWEST AND THRU THE FA DURING THE DAY SAT AND SAT NIGHT DELIVERING VERY COLD AIR. ANY SIGNIFICANT PRECIP WITH THIS SYSTEM WILL BE OFF TO THE N AND NE INTO THE GREAT LAKES AND CANADA. LIKELY TO BE SOME FLURRIES OR LIGHT SNOW SHOWERS PRE AND ESPECIALLY POST CFP BUT OF NO CONSEQUENCE. TRS

&&

.AVIATION DISCUSSION... 538 AM CST

THE SNOW COVER WILL KEEP THE ATMOSPHERE COLDER THAN WITHOUT SNOW BELOW 930 MB TODAY AND TONIGHT. THIS IS SEEN ON THE 1205 UTC ACARS SOUNDING FROM ROCKFORD AND THE 1148 UTC SOUNDING AT ORD AS AN INVERSION AROUND 900 MB. SOUTHWEST WIND IS BRINGING WARM AIR INTO THE REGION AND MIX OF THE WARM AIR AND COLD AIR IS FORMING STRATUS CLOUDS. A WEAK SURFACE TROUGH OVER SOUTHERN WISCONSIN WILL PASS THROUGH THIS AFTERNOON AND THE WIND WILL SHIFT TO THE WEST. THERE WILL BE SOME DRIER AND COLDER AIR ABOVE THE BOUNDARY LAYER. SO THE STRATUS CLOUDS MAY BECOME SCATTERED THIS AFTERNOON. BUT THE STRATUS MAY COME BACK WITH SOME FOG TONIGHT AS THE WIND BECOMES LIGHT AND THE INVERSION SETS UP. WILL ADD MVFR CEILINGS TONIGHT. &&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVY FOR ILLINOIS AND INDIANA NEARSHORE UNTIL 1 PM CST.

&&

$$

.EVENING UPDATE...

UPDATED EVENING FORECAST TO REFLECT CLOUD TRENDS. ALBERTA CLIPPER CURRENTLY SEEN ON WATER VAPOR SATELLITE CURRENTLY OVER WISCONSIN WILL DIVE SOUTHWARD AND MOVE ACROSS EASTERN KENTUCKY EARLY TOMORROW. MOISTURE IS LACKING AND AIR REMAINS UNSATURATED ABOVE 800 MB ACCORDING TO NAM CROSS SECTIONS. HOWEVER...STRONG COLD AIR ADVECTION WILL BEGIN IN EARNEST EARLY TOMORROW. AS LOW LEVEL LAPSE RATES STEEPEN...SCATTERED SNOW SHOWERS STILL EXPECTED TO DEVELOP ACROSS EASTERN INDIANA...AND MOVE ACROSS OUR NORTHEASTERN COUNTIES. HAVE PUSHED BACK THE POSSIBLE ONSET OF SNOW SHOWERS TO THE PRE-DAWN HOURS TO CORRESPOND WITH COLDER AIR`S ARRIVAL. SOME LIGHT LOCALIZED ACCUMULATIONS STILL POSSIBLE ACROSS THE BLUEGRASS REGION UNDER THE HEAVIER SHOWERS. TEMPERATURES WILL NOT RISE MUCH TOMORROW...AS BLUSTERY NORTHWEST WINDS WILL DEVELOP BY LATE MORNING AS COLDER AIR ARRIVES. JSD

.SHORT TERM (TONIGHT-THURSDAY)...

DUE TO CLIPPER SYSTEM...NE SECTIONS OF THE LMK CWA SAW MEASURABLE SNOW EARLY THIS MORNING...WITH AMOUNTS RANGING FROM A FEW TENTHS TO NEARLY 1.5 INCHES. NUMEROUS TRAFFIC ACCIDENTS OCCURRED DURING THE MORNING COMMUTE. TEMPERATURES HAVE RISEN ABOVE FREEZING...MELTING NEARLY ALL THE SNOW PER WEBCAMS. POWERFUL JET STREAK OVERHEAD TODAY...EARLIER 737 AIRCRAFT OBSERVATION AT FL380 NEAR SDF INDICATED A 183KT WESTERLY WIND (AND MODERATE TURBULENCE).

FOCUS FOR THIS PERIOD IS ON YET ANOTHER CLIPPER SYSTEM FCST TO ROLL THOUGH THE DISTRICT THURSDAY. CURRENTLY FEATURE IS POSITIONED OVER WRN SECTIONS OF ONTARIO...AND IS FCST TO DROP QUICKLY FROM SRN INDIANA AT 12Z/THU INTO ERN KY BY 18Z/THU. AHEAD OF THIS UPPER WAVE FCST SOUNDINGS FROM GFS/NAM SHOW STEEPENING LAPSE RATES LATE TONIGHT AND THURSDAY WITH SATURATION INTO THE CRITICAL ICE CRYSTAL GENERATION LAYERS OVER NE 1/3 OF THE CWA...THOUGH GFS IS LESS AGGRESSIVE WITH SATURATION AS COMPARED TO THE NAM. SCT SHSN ARE EXPECTED OVER THE NRN/ERN ZONES FROM ROUGHLY 8Z TONIGHT THROUGH 15Z THURSDAY MORNING.

WE WILL GO WITH 30-40% POPS FOR THIS AREA...LESSER VALUES OVER REMAINDER OF CWA INCLUDING MOST OF SRN KY...WHERE ONLY FLURRIES WILL BE MENTIONED. BUFKIT DIAGNOSTICS FROM WETTER NAM PRODUCE AROUND 0.5 INCH OF SNOWFALL FROM MADISON INDIANA SE INTO THE FFT/LEX AREAS... WITH AROUND 0.25 INCH AT SDF. THESE VALUES SEEM REASONABLE...THOUGH THEY WILL BE LOCALIZED DEPENDING ON EXACTLY WHERE SNOW SHOWERS DEVELOP. AN SPS WILL BE ISSUED FOR OUR FAR NE COUNTIES HIGHLIGHTING POTENTIAL FOR MORE SNOW...AND SIMILAR IN NATURE TO THIS MORNINGS ACTIVITY...IT HAS THE POTENTIAL TO AFFECT THE MORNING DRIVE TOMORROW.

IN THE MEANTIME...CURRENT AREA OF LOW CLOUDS IS EXPECTED TO DISSIPATE AND/OR SLIDE SE SUCH THAT SKIES WILL GO PARTLY CLOUDY OR MOSTLY CLEAR OVER MUCH OF THE CWA FROM LATE AFTN INTO EARLY EVENING. THEN TOWARD 6Z LOW LEVEL RH FIELDS DEPICT CLOUDS RAPIDLY INCREASING INTO THE OVERNIGHT HOURS. REGARDING TEMPERATURES...HAVE FOLLOWED LATEST RUC PROJECTIONS FOR TONIGHT AND TOMORROW GIVEN IT`S RECENT GOOD PERFORMANCE. THIS YIELDS VERY SLOWLY FALLING TEMPS TONIGHT INTO THE UPPER 20S/LOWER 30S...WITH NEAR STEADY READINGS THURSDAY. STEEPENING LAPSE RATES WILL PROMOTE GUSTY WINDS THURSDAY...BUFKIT SUGGESTING GUSTS TO 20KTS OR SO POSSIBLE AND HAVE FOLLOWED THIS.

CS

.LONG TERM (THURSDAY NIGHT-WEDNESDAY)...

THURSDAY NIGHT AND FRIDAY...

COLD AIR ADVECTION WILL IN IN PLACE AT THE BEGINNING OF THIS FORECAST PERIOD WITH THE 8H ISOTHERM AT 00Z FRIDAY SOUTH OF THE FORECAST AREA. THIS IS IN THE WAKE OF A CLIPPER MOVING TO OUR SOUTHEAST. THIS CAA WILL BE SHORT LIVED AS THE NEXT CLIPPER SYSTEM BEGINS TO DROP SOUTH OUT OF CENTRAL CANADA. LOW LEVEL WINDS WILL BACK AND INCREASE FROM THE WEST FRIDAY AND A WARM FRONT WILL MOVE THROUGH THE AREA. BY 00Z SATURDAY H8 TEMPS WILL HAVE WARMED TO THE FREEZING MARK. SO AFTER A CLEAR AND COLD THURSDAY NIGHT...FRIDAY WILL BE BREEZY AND WARMER.

TEMPERATURES FRIDAY MORNING WILL START OUT IN THE LOWER 20S BUT WITH THE WARMING READINGS WILL RISE INTO THE LOWER AND MID 40S BY AFTERNOON. SOUTHWEST WINDS FRIDAY NIGHT WILL KEEP TEMPERATURES IN THE 30S WITH INCREASING CLOUDS.

SATURDAY THROUGH WEDNESDAY...

A GREAT LAKES AND OHIO VALLEY UPPER LEVEL TROUGH WILL REMAIN IN PLACE THROUGH THIS FORECAST PERIOD. EXTENDED MODELS ARE IN AGREEMENT ON BRINGING SEVERAL DISTURBANCES THROUGH THE FLOW WHICH WILL BRING SOME ADDITIONAL LIGHT RAIN OR SNOW TO THE AREA AS WELL AS REINFORCING COLD AIR.

THE FIRST WAVE WILL SHARPEN UP SATURDAY AND SLOWLY MOVE ACROSS THE REGION SUNDAY. WITH BACKING LOW LEVEL WINDS AHEAD OF THE DEEPENING TROUGH ENOUGH WARM AIR WILL FILTER INTO THE REGION TO PRODUCE LIGHT RAIN SATURDAY. COLDER AIR WILL OVERSPREAD THE LOWER OHIO VALLEY SATURDAY NIGHT SO ANY ADDITIONAL PRECIPITATION WILL BE IN THE FORM OF SNOW. WE WILL KEEP POPS IN THE LOW CHANCE CATEGORY BUT IF WE SEE PERSISTENCE IN THIS CLIPPER SYSTEM POPS WILL NEED TO BE RAISED ESPECIALLY OVER THE NORTHEAST PORTION OF THE FORECAST AREA.

A SECOND WAVE WILL DIG INTO THE REGION TUESDAY WITH SOME VARIATION IN THE MODELS ON THE LOCATION AND STRENGTH. FOR NOW WE WILL FOLLOW THE GFS AND KEEP THE FORECAST AREA DRY.

THE INITIAL SHOT OF COLD AIR SATURDAY NIGHT WILL DROP TEMPERATURES INTO THE 20S AND LOW 30S SUNDAY AND INTO THE TEENS AND 20S MONDAY WITH A SLIGHT WARM UP TUESDAY. COLDER TEMPERATURES WILL BE NOTED AGAIN WEDNESDAY AS THE SECOND CLIPPER MOVES TO THE SOUTHEAST.

--JA

.AVIATION (00Z TAFS)...

SATELLITE SHOWS BROAD FIELD OF STRATO-CU THAT WILL MOVE SOUTHEAST AND APPROACH THE OHIO RIVER AND SDF BY AROUND 02Z. MVFR CEILINGS WILL ARRIVE AT SDF AROUND 02Z AND LEX AROUND 4Z. FARTHER SOUTH...EXPECT MVFR CEILINGS AT BWG AROUND 04 TO 05Z

OVERCAST SKIES LATER TONIGHT WILL BE ASSOCIATED WITH A WEAK CLIPPER TYPE DISTURBANCE DROPPING SOUTHEAST ACROSS SOUTHERN INDIANA TOMORROW MORNING. ALTHOUGH TRACK WILL BE SIMILAR TO LAST NIGHT`S LIGHT SNOW PRODUCER...EXPECT LITTLE MORE THAN A COUPLE OF SNOW FLURRIES ACROSS SDF AND LEX AFTER 08Z. NO RESTRICTIONS TO VISIBILITIES ARE EXPECTED. CEILINGS MAY LOWER TO 1000 FEET DURING PREDAWN HOURS AT SDF AND BWG. WEST WINDS OF 5 TO 10 TOMORROW WILL VEER TO THE NORTHWEST BY TOMORROW MORNING AND FRESHEN TO 10 TO 20 MPH BY LATE MORNING AS COLD AIR ADVECTION WILL STEEPEN LAPSE RATES.

JSD

&&

.LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. &&

$$

.AVIATION (00Z TAFS)...

SATELLITE SHOWS BROAD FIELD OF STRATO-CU THAT WILL MOVE SOUTHEAST AND APPROACH THE OHIO RIVER AND SDF BY AROUND 02Z. MVFR CEILINGS WILL ARRIVE AT SDF AROUND 02Z AND LEX AROUND 4Z. FARTHER SOUTH...EXPECT MVFR CEILINGS AT BWG AROUND 04 TO 05Z

OVERCAST SKIES LATER TONIGHT WILL BE ASSOCIATED WITH A WEAK CLIPPER TYPE DISTURBANCE DROPPING SOUTHEAST ACROSS SOUTHERN INDIANA TOMORROW MORNING. ALTHOUGH TRACK WILL BE SIMILAR TO LAST NIGHT`S LIGHT SNOW PRODUCER...EXPECT LITTLE MORE THAN A COUPLE OF SNOW FLURRIES ACROSS SDF AND LEX AFTER 08Z. NO RESTRICTIONS TO VISIBILITIES ARE EXPECTED. CEILINGS MAY LOWER TO 1000 FEET DURING PREDAWN HOURS AT SDF AND BWG. WEST WINDS OF 5 TO 10 TOMORROW WILL VEER TO THE NORTHWEST BY TOMORROW MORNING AND FRESHEN TO 10 TO 20 MPH BY LATE MORNING AS COLD AIR ADVECTION WILL STEEPEN LAPSE RATES.

JSD

.SHORT TERM (TONIGHT-THURSDAY)...

DUE TO CLIPPER SYSTEM...NE SECTIONS OF THE LMK CWA SAW MEASURABLE SNOW EARLY THIS MORNING...WITH AMOUNTS RANGING FROM A FEW TENTHS TO NEARLY 1.5 INCHES. NUMEROUS TRAFFIC ACCIDENTS OCCURRED DURING THE MORNING COMMUTE. TEMPERATURES HAVE RISEN ABOVE FREEZING...MELTING NEARLY ALL THE SNOW PER WEBCAMS. POWERFUL JET STREAK OVERHEAD TODAY...EARLIER 737 AIRCRAFT OBSERVATION AT FL380 NEAR SDF INDICATED A 183KT WESTERLY WIND (AND MODERATE TURBULENCE).

FOCUS FOR THIS PERIOD IS ON YET ANOTHER CLIPPER SYSTEM FCST TO ROLL THOUGH THE DISTRICT THURSDAY. CURRENTLY FEATURE IS POSITIONED OVER WRN SECTIONS OF ONTARIO...AND IS FCST TO DROP QUICKLY FROM SRN INDIANA AT 12Z/THU INTO ERN KY BY 18Z/THU. AHEAD OF THIS UPPER WAVE FCST SOUNDINGS FROM GFS/NAM SHOW STEEPENING LAPSE RATES LATE TONIGHT AND THURSDAY WITH SATURATION INTO THE CRITICAL ICE CRYSTAL GENERATION LAYERS OVER NE 1/3 OF THE CWA...THOUGH GFS IS LESS AGGRESSIVE WITH SATURATION AS COMPARED TO THE NAM. SCT SHSN ARE EXPECTED OVER THE NRN/ERN ZONES FROM ROUGHLY 8Z TONIGHT THROUGH 15Z THURSDAY MORNING.

WE WILL GO WITH 30-40% POPS FOR THIS AREA...LESSER VALUES OVER REMAINDER OF CWA INCLUDING MOST OF SRN KY...WHERE ONLY FLURRIES WILL BE MENTIONED. BUFKIT DIAGNOSTICS FROM WETTER NAM PRODUCE AROUND 0.5 INCH OF SNOWFALL FROM MADISON INDIANA SE INTO THE FFT/LEX AREAS... WITH AROUND 0.25 INCH AT SDF. THESE VALUES SEEM REASONABLE...THOUGH THEY WILL BE LOCALIZED DEPENDING ON EXACTLY WHERE SNOW SHOWERS DEVELOP. AN SPS WILL BE ISSUED FOR OUR FAR NE COUNTIES HIGHLIGHTING POTENTIAL FOR MORE SNOW...AND SIMILAR IN NATURE TO THIS MORNINGS ACTIVITY...IT HAS THE POTENTIAL TO AFFECT THE MORNING DRIVE TOMORROW.

IN THE MEANTIME...CURRENT AREA OF LOW CLOUDS IS EXPECTED TO DISSIPATE AND/OR SLIDE SE SUCH THAT SKIES WILL GO PARTLY CLOUDY OR MOSTLY CLEAR OVER MUCH OF THE CWA FROM LATE AFTN INTO EARLY EVENING. THEN TOWARD 6Z LOW LEVEL RH FIELDS DEPICT CLOUDS RAPIDLY INCREASING INTO THE OVERNIGHT HOURS. REGARDING TEMPERATURES...HAVE FOLLOWED LATEST RUC PROJECTIONS FOR TONIGHT AND TOMORROW GIVEN IT`S RECENT GOOD PERFORMANCE. THIS YIELDS VERY SLOWLY FALLING TEMPS TONIGHT INTO THE UPPER 20S/LOWER 30S...WITH NEAR STEADY READINGS THURSDAY. STEEPENING LAPSE RATES WILL PROMOTE GUSTY WINDS THURSDAY...BUFKIT SUGGESTING GUSTS TO 20KTS OR SO POSSIBLE AND HAVE FOLLOWED THIS.

CS

.LONG TERM (THURSDAY NIGHT-WEDNESDAY)...

THURSDAY NIGHT AND FRIDAY...

COLD AIR ADVECTION WILL IN IN PLACE AT THE BEGINNING OF THIS FORECAST PERIOD WITH THE 8H ISOTHERM AT 00Z FRIDAY SOUTH OF THE FORECAST AREA. THIS IS IN THE WAKE OF A CLIPPER MOVING TO OUR SOUTHEAST. THIS CAA WILL BE SHORT LIVED AS THE NEXT CLIPPER SYSTEM BEGINS TO DROP SOUTH OUT OF CENTRAL CANADA. LOW LEVEL WINDS WILL BACK AND INCREASE FROM THE WEST FRIDAY AND A WARM FRONT WILL MOVE THROUGH THE AREA. BY 00Z SATURDAY H8 TEMPS WILL HAVE WARMED TO THE FREEZING MARK. SO AFTER A CLEAR AND COLD THURSDAY NIGHT...FRIDAY WILL BE BREEZY AND WARMER.

TEMPERATURES FRIDAY MORNING WILL START OUT IN THE LOWER 20S BUT WITH THE WARMING READINGS WILL RISE INTO THE LOWER AND MID 40S BY AFTERNOON. SOUTHWEST WINDS FRIDAY NIGHT WILL KEEP TEMPERATURES IN THE 30S WITH INCREASING CLOUDS.

SATURDAY THROUGH WEDNESDAY...

A GREAT LAKES AND OHIO VALLEY UPPER LEVEL TROUGH WILL REMAIN IN PLACE THROUGH THIS FORECAST PERIOD. EXTENDED MODELS ARE IN AGREEMENT ON BRINGING SEVERAL DISTURBANCES THROUGH THE FLOW WHICH WILL BRING SOME ADDITIONAL LIGHT RAIN OR SNOW TO THE AREA AS WELL AS REINFORCING COLD AIR.

THE FIRST WAVE WILL SHARPEN UP SATURDAY AND SLOWLY MOVE ACROSS THE REGION SUNDAY. WITH BACKING LOW LEVEL WINDS AHEAD OF THE DEEPENING TROUGH ENOUGH WARM AIR WILL FILTER INTO THE REGION TO PRODUCE LIGHT RAIN SATURDAY. COLDER AIR WILL OVERSPREAD THE LOWER OHIO VALLEY SATURDAY NIGHT SO ANY ADDITIONAL PRECIPITATION WILL BE IN THE FORM OF SNOW. WE WILL KEEP POPS IN THE LOW CHANCE CATEGORY BUT IF WE SEE PERSISTENCE IN THIS CLIPPER SYSTEM POPS WILL NEED TO BE RAISED ESPECIALLY OVER THE NORTHEAST PORTION OF THE FORECAST AREA.

A SECOND WAVE WILL DIG INTO THE REGION TUESDAY WITH SOME VARIATION IN THE MODELS ON THE LOCATION AND STRENGTH. FOR NOW WE WILL FOLLOW THE GFS AND KEEP THE FORECAST AREA DRY.

THE INITIAL SHOT OF COLD AIR SATURDAY NIGHT WILL DROP TEMPERATURES INTO THE 20S AND LOW 30S SUNDAY AND INTO THE TEENS AND 20S MONDAY WITH A SLIGHT WARM UP TUESDAY. COLDER TEMPERATURES WILL BE NOTED AGAIN WEDNESDAY AS THE SECOND CLIPPER MOVES TO THE SOUTHEAST.

--JA

&&

.LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. &&

$$

.AVIATION (06Z TAFS)... BOTH THE GFS AND NAM LOW LEVEL RH FIELDS POINT TO CLEARING SKIES OVER THE WESTERN FA 10-12Z AND IN THE EAST BY AFTN...THIS LOOKS TO BE A BIT TOO FAST CONSIDERING THE LATEST SAT TRENDS. CIGS 2000 TO 2500 FT UNTIL CLEARING...SOME LOWER CIGS 1200-15000 ERN SECS FOR THE FIRST TWO OR THREE HOURS. WILL INTROD MID CLDS IN ASSOCIATED WITH SHORT WAVE DROPPING SOUTHEAST INTO THE REGION DURING THE EARLY NIGHT HOURS THIS TUE EVE. --21

.EVENING UPDATE...

UPDATED ZONES TO TAKE OUT EVENING WORDING. LOWERED DEWPOINTS AND TEMPERATURES ACROSS THE NORTH HALF OF CWA TO REFLECT LATEST OBS. EARLIER...SOME LIGHT SLEET WAS REPORTED ACROSS CENTRAL KENTUCKY. RADAR RETURNS HAVE DIMINISHED CONSIDERABLY AND ASIDE FROM A FEW STRAY FLURRIES OR AN ICE PELLET...HAVE REMOVED POPS FROM THE FORECAST. EXTENSIVE LOW CLOUDS CONTINUE WEST ALL THE WAY THROUGH ILLINOIS. ANY CLEARING WILL HAVE TO WAIT UNTIL TOMORROW AFTERNOON AT THE EARLIEST.

.AVIATION (00Z TAFS)...

EXTENSIVE LOW STRATUS WILL CONTINUE OVERNIGHT THROUGH THE MORNING HOURS TUESDAY. PATCHY DRIZZLE OR FLURRIES MAY BRIEFLY REDUCE VISIBILITIES TO BELOW 5SM THIS EVENING. CEILINGS WILL REMAIN MVFR AND VARY BETWEEN 1 AND 1.5 THOUSAND FEET OVERNIGHT...BUT PERHAPS LOWER CLOSER TO ONE THOUSAND FEET AT LEX...DUE TO NORTHWEST FLOW AND HIGHER ELEVATION. SURFACE WINDS WILL REMAIN WEST NORTHWEST AT 5 TO 10 MPH OVERNIGHT..WITH 15-20 MPH WEST NORTHWEST WINDS AT 2000 FEET. DUE TO STRONG INVERSION AT 5000 FEET...LOW CLOUDS WILL BE SLOW TO ERODE...BUT MAY BECOME SCATTERED TUESDAY AFTERNOON. JSD

.SHORT TERM (TONIGHT-TUESDAY)...

EXTENSIVE LOW CLOUDS OVER THE ENTIRE OHIO VALLEY REGION TODAY. THIS COUPLED WITH WEAK COLD ADVECTION HAS LED TO STEADY OR SLOWLY FALLING TEMPS TODAY...IN THE MID-UPPER 30S MOST PLACES AS OF 19Z. SCT PRECIP ON RADAR...AND BASED ON SPOTTER REPORTS COUPLED WITH ACARS DATA... PTYPE IS A MIX OF -RA/-SN/-PL...BUT INTENSITIES ARE VERY LIGHT. EXPECT THIS TO CONTINUE FOR THE REMAINDER OF THE AFTN HOURS.

FCST SOUNDINGS SHOW LOW LEVEL LAPSE RATES STEEPENING INTO THE EVENING HOURS. THIS ALONG WITH LIFT FROM PASSING UPPER TROF WILL HELP CONTINUE POTENTIAL FOR PRECIP THIS EVENING...WILL WORD AS SLIGHT CHANCE OF -SHRA/-SHSN...HOWEVER AIRMASS ABOVE 800MB (ICE CRYSTAL LEVELS) IS FCST TO REMAIN ON THE DRY SIDE...SO PRECIP AMTS SHOULD BE LIGHT AND WE MAY END UP SEEING MORE OF A PATCHY LIGHT DRIZZLE/FLURRY TYPE DEAL. WILL MENTION ISLTD SLICK SPOTS POSSIBLE IN THE HWO FOR TONIGHT AND EARLY TUESDAY MORNING.

CHANCES FOR PRECIP SHOULD DIMINISH AFTER 6Z AS UPPER WAVE PASSES OFF TO THE EAST...BUT SKIES WILL REMAIN CLOUDY PER NAM/GFS FCST SOUNDINGS. BOTH SHOW CLOUD COVER DIMINISHING TUESDAY AS DRIER AIR ADVECTS IN FROM THE W/SW...WHICH IS OBSERVED IN VISIBLE SATELLITE OVER AR/OK ATTM. HOWEVER THAT MAY BE DELAYED DUE TO VERY STRONG INVERSION SEEN AROUND 850MB. OVERALL WILL TREND TOWARD PARTLY CLOUDY WORDING IN THE AFTN TUESDAY.

REGARDING TEMPS...USED A 50/50 BLEND OF NAM/GFS TEMPS WHICH YIELDED MIDDLE 20S MOST LOCATIONS FOR LOWS TONIGHT...AND UPPER 30S/LOWER 40S FOR HIGHS TUESDAY.

CS

.LONG TERM (TUESDAY NIGHT-MONDAY)...

TUES NIGHT-WED NIGHT...

THIS PERIOD BEGINS WITH THE UPPER FLOW PATTERN MAINLY ZONAL/SLIGHTLY NW. AT THE SFC...LOW PRESSURE AND ASSOCIATED FRONT EXTEND FROM HUDSON BAY SW TO SRN GREAT LAKES. A SHORTWAVE EMBEDDED IN WNW FLOW ALOFT IS LOCATED ACROSS THE NRN PLAINS. AT THIS TIME...THINK THE SFC FRONT FROM THE GREAT LAKES MAY STAY TO OUR NE FOR THE MOST PART...AND ONLY BRING A SLIGHT WIND SHIFT TO THE AREA WED MORNING. HOWEVER TIME-HEIGHT CROSS SECTIONS ACROSS OUR NE FROM THE NAM AND GFS INDICATE DEEPER MOISTURE FROM 06-12Z...EXTENDING INTO THE -5 TO -15 DEGREE C RANGE. THINK THAT ONLY TRACE AMOUNTS OF PRECIP WOULD OCCUR (IN THE FORM OF FLURRIES) SO MAY INSERT THIS INTO THE GRIDS. THINK A BETTER CHANCE RESIDES WITH THE UPPER PLAINS` SHORTWAVE DIVING SEWD ACROSS THE CWA WED NIGHT. THIS MAY HELP SPARK A FEW LIGHT SHOWERS ACROSS THE AREA...WITH THE BEST CHANCE ACROSS THE NERN CWA. THINK SLT CHC SNOW SHOWERS SHOULD DO THE TRICK. ANY PRECIP WOULD BE LIGHT IN NATURE.

THU-FRI...

THIS PERIOD WILL BE MAINLY DRY AS UPPER TROUGH MOVES OFF TO THE NE AND SFC HIGH PRESSURE TRIES TO NOSE IN FROM THE WEST. STILL A NW FLOW ALOFT WILL BE PRESENT ACROSS THE REGION...AND MAY HAVE SOME LINGERING FLURRIES ACROSS OUR NE THU MORN. WOULD BE A MINIMAL SHOT SO WILL NOT INSERT INTO GRIDS AT THIS TIME. MODELS HAVE BEEN TRENDING CLOSER TO THE ECMWF...WHICH HAS BEEN THE MOST CONSISTENT MODEL DOWNPLAYING THE SOUTHWARD ADVANCEMENT OF ARCTIC AIR. STILL...THINK TEMPS WILL HAVE A HARD TIME GETTING OUT OF THE 30S FOR THU UNDER THE NW FLOW (ESPECIALLY ACROSS OUR NE). TEMPS SHOULD SLOWLY MODERATE ON FRI...WITH VALUES CLOSER TO NORMAL.

SAT-MON...

THIS PERIOD POSES THE MOST UNCERTAINTY...HOWEVER FORECASTER CONFIDENCE INCREASING DUE TO THE CONSISTENCY WITH THE ECMWF. AT THE BEGINNING OF THIS PERIOD...UPPER FLOW ALOFT IS STILL A WNW FLOW...WITH A CUT-OFF LOW OVER THE SWRN CONUS FINALLY EJECTING INTO THE SRN PLAINS. MODERATING TEMPS CONTINUE WITH SWRLY SFC WINDS AND SLT RIDGING OVERHEAD. A SFC LOW IS LOCATED OVER THE GREAT LAKES REGION SAT MORN...WITH SWWD EXTENDING FRONT. THIS FRONT WILL LIKELY PASS THROUGH THE REGION SATURDAY...WHILE AT THE SAME TIME UPPER LOW EJECTING INTO PLAINS TRAVELS JUST TO OUR SOUTH. A COMBINATION OF THESE POSES A SLT PRECIP THREAT FOR THE AREA...HOWEVER QPF AMOUNTS LOOK VERY LIGHT AT THIS POINT SINCE OUR CWA RESIDES IN THE MIDDLE OF THE TWO NRN AND SRN STREAMS. WILL JUST CARRY SLT CHC POPS...AND WOULD LIKELY START OFF AS LIQUID. SAT NIGHT...PRECIP SHOULD SWITCH TO -SHSN AS TEMPS AT 850MB DROP TO AROUND -12 DEGREES C. UPPER TROUGH BEHIND NRN STREAM FRONT TRIES TO BRING ARCTIC AIR INTO THE REGION...HOWEVER TREND IS TO LIGHTEN THE PUNCH...WITH THE NE CONUS REALLY EXPERIENCING THE WORST OF THE ARCTIC AIR. COULD HAVE A CHC OF FLURRIES WITH THE UPPER TROUGH PASSAGE...BUT GIVEN VERY DRY ATMS WILL NOT INSERT INTO THE GRIDS FOR SUNDAY AT THIS TIME. DESPITE THE MODELS TRENDING TOWARD KEEPING THE COLDEST TEMPS TO OUR NE...ENSEMBLES STILL SHOW TEMPS 1 STD DEV BELOW NORM SUN-MON...SO WILL TREND TOWARD ROUGHLY 3-5 DEGREES BELOW NORMAL FOR THESE DAYS.

AL

&&

.AVIATION (00Z TAFS)...

EXTENSIVE LOW STRATUS WILL CONTINUE OVERNIGHT THROUGH THE MORNING HOURS TUESDAY. PATCHY DRIZZLE OR FLURRIES MAY BRIEFLY REDUCE VISIBILITIES TO BELOW 5SM THIS EVENING. CEILINGS WILL REMAIN MVFR AND VARY BETWEEN 1 AND 1.5 THOUSAND FEET OVERNIGHT...BUT PERHAPS LOWER CLOSER TO ONE THOUSAND FEET AT LEX...DUE TO NORTHWEST FLOW AND HIGHER ELEVATION. SURFACE WINDS WILL REMAIN WEST NORTHWEST AT 5 TO 10 MPH OVERNIGHT..WITH 15-20 MPH WEST NORTHWEST WINDS AT 2000 FEET. DUE TO STRONG INVERSION AT 5000 FEET...LOW CLOUDS WILL BE SLOW TO ERODE...BUT MAY BECOME SCATTERED TUESDAY AFTERNOON. JSD

&&

.LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE.

&&

$$

.UPDATE... RADAR INDICATED SOME INCREASE IN LES INTENSITY WITH BANDS GENERALLY ALIGNED WITH 330-340 CBL FLOW. HOWEVER...LES REMAINED RELATIVELY UNORGANIZED WITH FEW COHERENT BANDS AS WINDS CONTINUED TO SLOWLY VEER. 01Z KSAW TAMDAR SNDG INDICATED -19C AT 5K FT INVERSION TOP (850 MB). CAA IS EXPECTED TO DROP 850 MB TEMPS TO NEAR -22C LATER TONIGHT WHICH WILL LEAD DECREASE DEPTH OF THE SNOW GROWTH LAYER. THE 00Z NAM CONTINUED TO SHOW BEST 950 MB CONV LATE TONIGHT INTO EARLY THU BETWEEN MARQUETTE AND MUNISING WHILE THE RUC13 WITH MORE NNE WINDS OVER THE ERN LAKE PUSHED THIS AREA MORE INTO MARQUETTE. THE 00Z LCL HIGH RES WRF-ARW AS A COMPROMISE SEEMED TO BEST FIT EXPECTED LES EVOLUTION WITH BANDS INTO MARQUETTE AND HARVEY AND TOWARD AU TRAIN. DESPITE THE STRENGTH OF THE COLD AIR...THE VERY DRY ARCTIC AIR MASS AND LIMITED SHOULD STILL LIMIT SNOWFALL AMOUNTS INTO THE 2-5 INCH RANGE INTO EARLY THU. OVER THE WEST THE SHORTER FETCH LENGTH SHOULD KEEP ACCUMULATIONS IN THE 1-3 INCH RANGE WITH THE HIGHER AMOUNTS FROM WHITE PINE TOWARD WAKEFIELD...PER NAM LOW LVL CONV.

OVERALL ONLY MINOR ADJUSTMENTS MADE TO GOING FCST.

&&

JLB

.SHORT TERM DISCUSSION (CURRENT THRU THU)...ISSUED 326 PM EST WED JAN 24 2007

12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE WRN RDG/ERN TROF UPR FLOW WITH POSITIVE PNA/NEGATIVE NAO PATTERN LOCKING COLD AIR IN PLACE OVER ERN NAMERICA. TWO SHRTWVS OF CONCERN EMBEDDED WITHIN THIS FLOW. THE FIRST IS CURRENTLY DROPPING FM MANITOBA INTO NW ONTARIO...AND THE SECOND IS MOVING FM HUDSON BAY INTO NW ONTARIO. AREA OF THICKER CLD/SOME -SN ASSOCIATED WITH FIRST SHRTWV/DPVA/H85-5 QVECTOR CNVGC IS NOW MOVING INTO THE WRN CWA...BUT OVERALL PCPN COVG/INTENSITY LIMITED BY DRY AIR SHOWN ON THE 12Z INL/YPL/YQD RAOBS AND MINIMAL ISENTROPIC LIFT. BACK EDGE OF THICKER CLD ASSOCIATED WITH THIS SHRTWV IS MOVING STEADILY S THRU NW ONTARIO...SFC DWPT NEAR -20F AT YPL. FARTHER E...LES BANDS ARE PUSHING INTO THE NW SN BELTS E OF MQT AS COLD AIR TO THE NW (12Z H85 TEMP AT YPL -21C) FLOWS ACRS THE RELATIVELY WARM WATERS OF LK SUP. ALTHOUGH THESE BANDS APPEAR TO BE GETTING MORE DISORGANIZED WITH INCRSD WIND SHEAR AHEAD OF SHRTWV...SOME REFLECTIVITIES STILL AOA 28DBZ IN WRN MOST BAND OVER WRN ALGER COUNTY IN AXIS OF LLVL CNVGC BTWN MORE WLY FLOW ACRS THE WCNTRL CWA AND ELY FLOW OFF ONTARIO FARTHER TO THE E. EARLIER SPOTTER REPORT NEAR AU TRAIN INDICATED SN FALLING AT THE RATE OF AN INCH/HR UNDER THIS BAND. NO WX AND HARDLY ANY CLD ASSOCIATED WITH SECOND SHRTWV AS 12Z MOOSONEE RAOB SHOWS PWAT ONLY 0.06 INCH.

MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LES TRENDS AND AMTS/GOING HEADLINES/NEED FOR ADDITIONAL HEADLINES.

TNGT/THU...SHRTWV MOVING FM MANITOBA FCST TO MOVE INTO NRN WI BY 00Z AND THEN INTO THE OH VALLEY BY 12Z THU. SECOND SHRTWV FCST TO REACH NR ANJ BY 12Z THU BEFORE MOVING INTO NY STATE BY 00Z FRI. ALTHOUGH DPVA/H85-5 QVECTOR CNVGC BEHIND FIRST SHRTWV WL BE EXITING THE FA BY EARLY THIS EVNG...EXPECT LES IN THE COLD NNW FLOW IN THE WAKE OF THIS SHRTWV TO BE ONGOING DOWNWIND OF LK SUP. GFS FCST SDNGS SHOW FAIRLY DEEP MSTR AT 00Z INCLUDING FVRBL SN GROWTH LYR UP TO H6 OVER THE E WITH FAIRLY UNIDIRECTIONAL NNW FLOW BLO INVNR AS HI AS H8. IN ADDITION TO EARLIER ADVY ISSUED FOR GOGEBIC/ONTONAGON ZNS AND WRNG FOR ALGER COUNTY WHERE LLVL CNVGC WL BE MOST PERSISTENT ALG EXISTING SFC TROF...WL POST ADVY FOR MQT/SCHOOLCRAFT/DELTA COUNTIES TO ACCOUNT FOR FVRBL NLY FLOW AND DPVA/SOME H85-5 QVECTOR CNVGC ACCOMPANYING PASSAGE OF SECOND SHRTWV LATER OVER THE E. SINCE THESE DYNAMICS WILL MISS THE WRN ZNS (SECOND SHRTWV TRACKING WELL TO THE E) AND ARRIVING DRIER AIR BEGINNING TNGT WL HAVE A SHORTER FETCH OVER WRN LK SUP...ADVYS FOR WRN ZNS ONLY NECESSARY THRU 12Z THU... WHEN GFS FCST SDNG FOR IWD SHOWS INVRN BASE AT 12Z THU FALLING TO H9. CONSIDERED ADVY FOR LUCE COUNTY AS WELL...BUT SHORTER FETCH WITH BONE DRY AIRMASS UPSTREAM/POORER SN GROWTH WITH H85 TEMPS FALLING TOWARD -25C BY 12Z THU SUG HEADLINE NOT NECESSARY THERE. EXPECT LES TO DIMINISH EVEN OVER THE ERN ZNS LATER ON THU WITH APRCH OF SFC HI PRES/MORE ACYC FLOW/LOWERING INVRN BASE TO H9.

AS FOR TEMPS...STRONG NLY FLOW TNGT/LK SUP MODERATION SHOULD HOLD TEMPS UP HIER TNGT THAN MIGHT BE EXPECTED FOR INCOMING DRY AIR. EXPECT LOWEST TEMPS OVER THE ERN ZNS WITH POTENTIAL LAND BREEZE OFF ONTARIO. LO END OF MOS GUIDANCE SEEMS MORE APPROPRIATE FOR HI TEMPS ON THU.

COORDINATED WITH DLH/GRB.

KC

.LONG TERM (THURSDAY NIGHT THROUGH WEDNESDAY)...

SLEET OR FREEZING DRIZZLE FOR THURSDAY NIGHT INTO FRIDAY? AT THIS TIME...THIS SEEMS MORE LIKELY TO OUR SOUTH...AND WHILE UTILIZING THE GFS...WITH MORE MOISTURE AND COOLER AIR OVER OUR AREA...WILL KEEP SNOW ACROSS THE UPPER PENINSULA. THE 500MB RIDGE SHOULD BE DIRECTLY OVERHEAD AROUND 18Z FRIDAY. STILL...WITH THE UPSTREAM LOW GEARING UP TO SINK TOWARDS UPPER MICHIGAN...AN EXTENDED DRY PERIOD IS NOT FIGURED AS THE SURFACE HIGH PRESSURE CENTER IS LONG GONE...AND OVER THE EASTERN GREAT LAKES BY THIS TIME.

AS FOR FRIDAY NIGHT...OUR FORECAST TEMPS SEEMED TOO LOW WHEN COMPARED TO UPDATED MODEL DATA. WENT AHEAD AND ADJUSTED UP FROM 1-3 DEGREES ACROSS THE BOARD...WHICH IS STILL TOWARDS THE LOWER END OF GUIDANCE VALUES. CAA WILL BE MOVING IN AT THIS TIME...AS THE CLIPPER SYSTEM MOVES OUT OF OF SOUTHEASTERN MANITOBA FRIDAY...AND OVER THE EASTERN THIRD OF LAKE SUPERIOR BY O6Z SATURDAY. WE MAY NEED TO MAKE FURTHER ADJUSTMENTS TO THE TEMPERATURES FOR THIS PERIOD...AS I HAVE HAVE A HARD TIME BELIEVING THAT WE WOULD BE ABLE TO CLEAR OUT...TO REALIZE THE COOLER GUIDANCE TEMPS CLOSE TO OUR CURRENT FORECAST WITH THE AMOUNT OF LOW LEVEL MOISTURE BEING PRODUCED BY THE MODELS FRIDAY NIGHT INTO SATURDAY MORNING. POP WISE FOR FRIDAY NIGHT...WITH DISCREDITING THE NAM WHICH HAD PROBLEMS IN THE NEAR TERM WITH TEMPERATURES OVER THE CWA...AND THE FACT THAT DURING THE FRIDAY INTO SATURDAY TIME PERIOD THAT IT IS FURTHER NORTH AND EAST OF A MAJORITY OF THE OTHER MODELS...HAVE A HARD TIME GOING WITH ANY DRY AREAS. STILL...BELIEVE THAT THE BEST CHANCE FOR ANY PLACE TO STAY DRY WILL BE ACROSS THE SOUTH...SO HAVE MANIPULATED THE POP AND WEATHER GRIDS ACCORDINGLY. COOLER AIR WILL SLIDE INTO THE AREA...AS NOTED PREVIOUSLY...WITH 850MB TEMPERATURES FALLING FROM ROUGHLY -10C AT 00Z SATURDAY TO -22C BY 12Z SUNDAY (THEN CONTINUING AROUND THIS MARK THROUGH MONDAY AFTERNOON). AS THIS COOLER AIR SLIDES IN...AND WE HAVE AN EXTENDED PERIOD OF NORTH TO NORTHWESTERLY FLOW NEAR THE SURFACE...WE WILL NEED TO CONTINUE MONITORING FOR THE POSSIBILITY OF ENHANCE PRECIPITATION DUE TO LAKE EFFECT...PARTICULARLY 12Z SATURDAY THROUGH 00Z SUNDAY ENHANCED BY THE COLD FRONT SLIDING SOUTHWARD ACROSS THE FORECAST AREA.

OTHERWISE FOR SUNDAY THROUGH WEDNESDAY (DAYS 4 - 7)...COOLER HAS BEEN THE TREND TODAY...ADJUSTING TEMPERATURES FROM DAY 4 (SUNDAY) ON DOWNWARD. FOR THE MOST PART...DID NOT DEVIATE MUCH FROM HPC GUIDANCE FOR THIS PERIOD...WITH ONLY SMALL SCALE ADJUSTMENTS DEEMED NECESSARY AT THIS TIME. THE PRELIMINARY AND FINAL GUIDANCE CONTINUES TO DEVIATE FROM THE NAM...AND FOLLOWS THE GFS FOR THE MOST PART OVER OUR REGION.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FOR MIZ006 TNGT THRU 22Z THU. LAKE EFFECT SNOW ADVISORY FOR MIZ005-013 TNGT UNTIL 18Z THU. LAKE EFFECT SNOW ADVISORY FOR MIZ002-009 TNGT THRU 12Z THU. LAKE EFFECT SNOW ADVISORY FOR MIZ014-085 TNGT THRU 22Z THU.

&&

$$

.SHORT TERM...KC .LONG TERM...KF

.AVIATION (06Z TAFS)...

MAIN CONCERN OVER THE NEXT SEVERAL HOURS IS AREA OF SNOW DROPPING SOUTH OUT OF INDIANA. THIS SNOW WILL AFFECT SDF AND LEX TERMINALS THE MOST...PRIMARILY BETWEEN 09Z AND 16Z. BWG WILL CATCH A FEW FLURRIES FROM IT BUT THAT SHOULD BE ABOUT IT THERE. CEILINGS AND VISIBILITIES WILL GO MVFR...AND DURING THE HEIGHT OF THE SNOW SHOWERS AT SDF AND LEX WILL LIKELY DROP SLIGHTLY BELOW 2000 FEET.

AS THE AXIS OF THE UPPER TROF RESPONSIBLE FOR THESE SNOW SHOWERS MOVES TO OUR EAST THE SNOW SHOULD EXIT AS WELL...BY MIDMORNING. WITH HIGH PRESSURE NOSING IN FROM THE WEST SKIES WILL MOSTLY CLEAR BY LATE MORNING AT SDF AND BWG. WILL KEEP THE CLOUDS IN AT LEX LONGER AS THE MOISTURE TAKES A BIT MORE TIME TO SCOUR OUT OF THAT AREA IN THESE NORTHWEST FLOW SITUATIONS PLUS SOME CLOUD ENHANCEMENT COMING OFF LAKE MICHIGAN.

BY LATE AFTERNOON CLOUDS SHOULD BE GONE AND CLEAR SKIES WILL CONTINUE INTO THE EVENING.

WINDS COULD GET A BIT GUSTY OUT OF THE NORTH TODAY AS THE GRADIENT TIGHTENS.

13

&&

.EVENING UPDATE...

UPDATED EVENING FORECAST TO REFLECT CLOUD TRENDS. ALBERTA CLIPPER CURRENTLY SEEN ON WATER VAPOR SATELLITE CURRENTLY OVER WISCONSIN WILL DIVE SOUTHWARD AND MOVE ACROSS EASTERN KENTUCKY EARLY TOMORROW. MOISTURE IS LACKING AND AIR REMAINS UNSATURATED ABOVE 800 MB ACCORDING TO NAM CROSS SECTIONS. HOWEVER...STRONG COLD AIR ADVECTION WILL BEGIN IN EARNEST EARLY TOMORROW. AS LOW LEVEL LAPSE RATES STEEPEN...SCATTERED SNOW SHOWERS STILL EXPECTED TO DEVELOP ACROSS EASTERN INDIANA...AND MOVE ACROSS OUR NORTHEASTERN COUNTIES. HAVE PUSHED BACK THE POSSIBLE ONSET OF SNOW SHOWERS TO THE PRE-DAWN HOURS TO CORRESPOND WITH COLDER AIR`S ARRIVAL. SOME LIGHT LOCALIZED ACCUMULATIONS STILL POSSIBLE ACROSS THE BLUEGRASS REGION UNDER THE HEAVIER SHOWERS. TEMPERATURES WILL NOT RISE MUCH TOMORROW...AS BLUSTERY NORTHWEST WINDS WILL DEVELOP BY LATE MORNING AS COLDER AIR ARRIVES. JSD

.SHORT TERM (TONIGHT-THURSDAY)...

DUE TO CLIPPER SYSTEM...NE SECTIONS OF THE LMK CWA SAW MEASURABLE SNOW EARLY THIS MORNING...WITH AMOUNTS RANGING FROM A FEW TENTHS TO NEARLY 1.5 INCHES. NUMEROUS TRAFFIC ACCIDENTS OCCURRED DURING THE MORNING COMMUTE. TEMPERATURES HAVE RISEN ABOVE FREEZING...MELTING NEARLY ALL THE SNOW PER WEBCAMS. POWERFUL JET STREAK OVERHEAD TODAY...EARLIER 737 AIRCRAFT OBSERVATION AT FL380 NEAR SDF INDICATED A 183KT WESTERLY WIND (AND MODERATE TURBULENCE).

FOCUS FOR THIS PERIOD IS ON YET ANOTHER CLIPPER SYSTEM FCST TO ROLL THOUGH THE DISTRICT THURSDAY. CURRENTLY FEATURE IS POSITIONED OVER WRN SECTIONS OF ONTARIO...AND IS FCST TO DROP QUICKLY FROM SRN INDIANA AT 12Z/THU INTO ERN KY BY 18Z/THU. AHEAD OF THIS UPPER WAVE FCST SOUNDINGS FROM GFS/NAM SHOW STEEPENING LAPSE RATES LATE TONIGHT AND THURSDAY WITH SATURATION INTO THE CRITICAL ICE CRYSTAL GENERATION LAYERS OVER NE 1/3 OF THE CWA...THOUGH GFS IS LESS AGGRESSIVE WITH SATURATION AS COMPARED TO THE NAM. SCT SHSN ARE EXPECTED OVER THE NRN/ERN ZONES FROM ROUGHLY 8Z TONIGHT THROUGH 15Z THURSDAY MORNING.

WE WILL GO WITH 30-40% POPS FOR THIS AREA...LESSER VALUES OVER REMAINDER OF CWA INCLUDING MOST OF SRN KY...WHERE ONLY FLURRIES WILL BE MENTIONED. BUFKIT DIAGNOSTICS FROM WETTER NAM PRODUCE AROUND 0.5 INCH OF SNOWFALL FROM MADISON INDIANA SE INTO THE FFT/LEX AREAS... WITH AROUND 0.25 INCH AT SDF. THESE VALUES SEEM REASONABLE...THOUGH THEY WILL BE LOCALIZED DEPENDING ON EXACTLY WHERE SNOW SHOWERS DEVELOP. AN SPS WILL BE ISSUED FOR OUR FAR NE COUNTIES HIGHLIGHTING POTENTIAL FOR MORE SNOW...AND SIMILAR IN NATURE TO THIS MORNINGS ACTIVITY...IT HAS THE POTENTIAL TO AFFECT THE MORNING DRIVE TOMORROW.

IN THE MEANTIME...CURRENT AREA OF LOW CLOUDS IS EXPECTED TO DISSIPATE AND/OR SLIDE SE SUCH THAT SKIES WILL GO PARTLY CLOUDY OR MOSTLY CLEAR OVER MUCH OF THE CWA FROM LATE AFTN INTO EARLY EVENING. THEN TOWARD 6Z LOW LEVEL RH FIELDS DEPICT CLOUDS RAPIDLY INCREASING INTO THE OVERNIGHT HOURS. REGARDING TEMPERATURES...HAVE FOLLOWED LATEST RUC PROJECTIONS FOR TONIGHT AND TOMORROW GIVEN IT`S RECENT GOOD PERFORMANCE. THIS YIELDS VERY SLOWLY FALLING TEMPS TONIGHT INTO THE UPPER 20S/LOWER 30S...WITH NEAR STEADY READINGS THURSDAY. STEEPENING LAPSE RATES WILL PROMOTE GUSTY WINDS THURSDAY...BUFKIT SUGGESTING GUSTS TO 20KTS OR SO POSSIBLE AND HAVE FOLLOWED THIS.

CS

.LONG TERM (THURSDAY NIGHT-WEDNESDAY)...

THURSDAY NIGHT AND FRIDAY...

COLD AIR ADVECTION WILL IN IN PLACE AT THE BEGINNING OF THIS FORECAST PERIOD WITH THE 8H ISOTHERM AT 00Z FRIDAY SOUTH OF THE FORECAST AREA. THIS IS IN THE WAKE OF A CLIPPER MOVING TO OUR SOUTHEAST. THIS CAA WILL BE SHORT LIVED AS THE NEXT CLIPPER SYSTEM BEGINS TO DROP SOUTH OUT OF CENTRAL CANADA. LOW LEVEL WINDS WILL BACK AND INCREASE FROM THE WEST FRIDAY AND A WARM FRONT WILL MOVE THROUGH THE AREA. BY 00Z SATURDAY H8 TEMPS WILL HAVE WARMED TO THE FREEZING MARK. SO AFTER A CLEAR AND COLD THURSDAY NIGHT...FRIDAY WILL BE BREEZY AND WARMER.

TEMPERATURES FRIDAY MORNING WILL START OUT IN THE LOWER 20S BUT WITH THE WARMING READINGS WILL RISE INTO THE LOWER AND MID 40S BY AFTERNOON. SOUTHWEST WINDS FRIDAY NIGHT WILL KEEP TEMPERATURES IN THE 30S WITH INCREASING CLOUDS.

SATURDAY THROUGH WEDNESDAY...

A GREAT LAKES AND OHIO VALLEY UPPER LEVEL TROUGH WILL REMAIN IN PLACE THROUGH THIS FORECAST PERIOD. EXTENDED MODELS ARE IN AGREEMENT ON BRINGING SEVERAL DISTURBANCES THROUGH THE FLOW WHICH WILL BRING SOME ADDITIONAL LIGHT RAIN OR SNOW TO THE AREA AS WELL AS REINFORCING COLD AIR.

THE FIRST WAVE WILL SHARPEN UP SATURDAY AND SLOWLY MOVE ACROSS THE REGION SUNDAY. WITH BACKING LOW LEVEL WINDS AHEAD OF THE DEEPENING TROUGH ENOUGH WARM AIR WILL FILTER INTO THE REGION TO PRODUCE LIGHT RAIN SATURDAY. COLDER AIR WILL OVERSPREAD THE LOWER OHIO VALLEY SATURDAY NIGHT SO ANY ADDITIONAL PRECIPITATION WILL BE IN THE FORM OF SNOW. WE WILL KEEP POPS IN THE LOW CHANCE CATEGORY BUT IF WE SEE PERSISTENCE IN THIS CLIPPER SYSTEM POPS WILL NEED TO BE RAISED ESPECIALLY OVER THE NORTHEAST PORTION OF THE FORECAST AREA.

A SECOND WAVE WILL DIG INTO THE REGION TUESDAY WITH SOME VARIATION IN THE MODELS ON THE LOCATION AND STRENGTH. FOR NOW WE WILL FOLLOW THE GFS AND KEEP THE FORECAST AREA DRY.

THE INITIAL SHOT OF COLD AIR SATURDAY NIGHT WILL DROP TEMPERATURES INTO THE 20S AND LOW 30S SUNDAY AND INTO THE TEENS AND 20S MONDAY WITH A SLIGHT WARM UP TUESDAY. COLDER TEMPERATURES WILL BE NOTED AGAIN WEDNESDAY AS THE SECOND CLIPPER MOVES TO THE SOUTHEAST.

--JA

&&

.LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. &&

$$

.SHORT TERM... UPPER LEVEL RIDGE OVER THE NORTHERN ROCKIES WILL SHIFT OVER THE REGION AND MAKE FOR A RELATIVELY MILD DAY. HOWEVER TEMPS STARTING OUT COLD IN THE NORTHEAST ZONES. UPPER LEVEL LOW OVER WESTERN CANADA WILL MOVE OVER SOUTHERN CANADA FRI NIGHT WITH 200 METER HEIGHT FALLS FORECAST. GOOD WARM ADVECTION SHOULD OCCUR EAST OF UPPER LOW.

TAMDAR SOUNDINGS SHOW HIGHER TEMPERATURES AND HIGHER MID LEVEL MOISTURE OVER WESTERN ZONES THAN IN THE EASTERN ZONES. CANADIAN RADAR SHOWING SOME RETURNS ALONG SOUTHERN MANITOBA MOVING SOUTHEAST IN AREA OF BEST LOW LEVEL WARM ADVECTION. FEW RETURNS ON KMVX OVER NORTHWEST ZONES ALSO MOVING SOUTHEAST. SOME 850 AND 700 HPA FRONTOGENESIS NOTED ALONG NORTHERN BORDER TODAY. WILL ADD CHANCE FOR DUSTING OF SNOW TODAY MAINLY IN THE NORTHERN VALLEY.

HAVE RAISED TEMPS FOR FRI NIGHT AS MODELS EXPECT LOW LEVEL ADIABATIC CONDITIONS FRI NIGHT THROUGH SAT MORNING.

.LONG TERM... TEMPERATURES TWEAKED.

&&

.FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. &&

$$

HOPPES

.MORNING DISCUSSION... 930 AM CST

INHERITED FORECAST SEEMS TO HAVE THE LAKE EFFECT SNOW SITUATION WELL IN HAND. EXPECTING A FEW MORE HOURS OF LAKE EFFECT SNOW SHOWERS ACROSS NORTHEAST PORTER COUNTY BEFORE SNOW TAPERS TO FLURRIES. REPORTS ARE TOUGH TO COME BY THIS MORNING ACROSS NORTHEAST PORTER COUNTY...BUT DID RECEIVE A REPORT OF 1 TO 2 INCHES OF SNOW IN WANATAH JUST EAST OF THE PORTER COUNTY LINE. 1 TO 3 INCHES STILL DOES SEEM TO BE IN ORDER IN TERMS OF SNOWFALL ACCUMULATIONS ACROSS NORTHEAST PORTER COUNTY WITH SOME LOCALIZED HIGHER AMOUNTS CLOSER TO 4 INCHES POSSIBLE ACROSS THE EXTREME NORTHEAST PART OF THE COUNTY.

OTHERWISE MOSTLY SUNNY SKIES PERSIST ACROSS REMAINDER OF THE FORECAST AREA EXCEPT IN NORTHWEST ILLINOIS WHERE LOW CLOUDS ARE LINGERING CLOSER TO THE LOW LEVEL RIDGE AXIS. AT THIS TIME...EXPECTING STRENGTHENING SUBSIDENCE SHOULD PREVENT SUBSTANTIAL CLOUD COVER ACROSS MUCH OF THE FORECAST AREA TODAY...SO WILL MAINTAIN PARTLY CLOUDY CONDITIONS THROUGH THE AFTERNOON. TEMPS/WINDS ALSO APPEAR TO BE ON TRACK.

MARSILI

&&

.DISCUSSION MORNING GRIDS/ZONES... 445 AM CST

NO SIGNIFICANT CHANGES NECESSARY TO GOING FORECAST...AND NO MAJOR WX CONCERNS OVER THE NEXT SEVERAL DAYS.

SHORT WAVE TROUGH CROSSED THROUGH THE REGION OVERNIGHT AND IS NOW MOVING INTO THE LOWER LAKES AND UPPER OH VALLEY WITH SUBSIDENCE AND DRYING IN ITS WAKE CLEARING OUT CLOUDS FROM MOST OF WI AND IL. WITH CORE OF COLD AIR OVER THE ONTARIO/QUEBEC BORDER THE DEPTH OF REINFORCING COLD AIR ACROSS THE WESTERN GREAT LAKES IS RATHER SHALLOW. LAKE EFFECT SHOW QUICKLY DEVELOPED EARLIER THIS MORNING WITH THE WESTERN EDGE CLIPPING EASTERN PORTER COUNTY AS THE BOUNDARY LAYER FLOW HAS VEERED TO NNW. FORECAST TEMPERATURE PROFILE OVER SOUTHERN LAKE MI INDICATES TOPS OF LAKE EFFECT CLOUDS TO REACH TO AROUND 7K FT ALLOWING MODERATELY VIGOROUS SNOW SHOWERS. WINDS ALREADY BACK TO NW BY 18Z SHIFTING THE LAKE EFFECT OUT OF THE FA LIMITING THE TIME OF POSSIBLE ACCUMULATION. FAR NE PORTER MAY SEE 1-3 INCHES THIS MORNING.

SURFACE RIDGE CROSSES AREA THIS EVENING WITH INCREASING SW LOW LEVEL FLOW OVERNIGHT. THIS IN RESPONSE TO LOW PRESSURE DEEPENING AND MOVING ACROSS SASKATCHEWAN TO MANITOBA BY FRI MORNING AS STRONG SHORT WAVE MOVES SE FROM NORTHERN B.C. WAA AND UVV SPREAD E INTO THE NORTHERN LAKES OVERNIGHT AND INTO THE CENTRAL LAKES DURING THE DAY FRI. SNOW IN THE ZONE OF STRONG ISENTROPIC LIFT WILL PASS BY TO THE N AND NE OF THE LOCAL AREA. AS THE SHORT WAVE CONTINUES ESE TO LAKE SUPERIOR FRI NIGHT THE ASSOCIATED SURFACE LOW MOVE INTO THE CENTRAL LAKES AND A COLD FRONT PUSHES SE INTO THE FA DELIVERING MORE COLD AIR DEEPER ACROSS THE PLAINS AND MIDWEST. DEW POINTS TO CLIMB IN THE MID 20S ON THE SW FLOW AHEAD OF THE COLD FRONT AND WITH FROPA FRI NIGHT STRONG SHALLOW CAA SETS IN AND A PERIOD OF LIGHT FREEZING DRIZZLE POSSIBLE POST FROPA.

A COUPLE MORE WAVES TO DROP INTO THE UPPER TROUGH SAT AND SUN DEEPENING IT ACROSS THE OH VALLEY. THESE IMPULSES TO GENERATE ONLY SOME FLURRIES EXCEPT POTENTIAL FOR LAKE EFFECT TO MOVE BACK INTO FAR NW FOR SUN DEPENDING ON HOW MUCH THE LOW LEVEL FLOW VEERS. WITH COLD AIR AND RELATIVELY WARM LAKE WATERS A LOW PRESSURE TROUGH TENDS TO LAY OUT E-W ACROSS THE UPPER GREAT LAKES AND THIS MAY TEND TO KEEP SURFACE WINDS ON SOUTHERN LAKE MI FROM THE NW VS NNW.

WITH THE UPPER TROUGH AXIS OVER THE GREAT LAKES SUN INTO MID WEEK TEMPS WILL BE BELOW NORMAL AFTER RUNNING NEAR NORMAL FRI AND SAT.

TRS

&&

.AVIATION... 616 AM CST

SOME VFR TO HIGH MVFR CLOUDS MAY MOVE INTO NORTH CENTRAL ILLINOIS THIS MORNING. A BAND OF CLOUDS WAS SEEN OVER WESTERN WISCONSIN THIS MORNING AT 11 AND 12 UTC. THE WIND FLOW IS FROM THE NORTHWEST AS SEEN ON THE PROFILER 850 MB WIND. WILL ADD A BROKEN VFR LAYER OVER RFD IN THIS MORNINGS FORECAST. THE ACARS SOUNDING SHOW A SHALLOW INVERSION AROUND 1330 FT AT RFD 848 UTC. THE WIND ABOVE THIS INVERSION INCREASES TO AROUND 30 KNOTS FROM THE NORTH. THE FORECAST WIND IS AROUND 9 KNOTS THIS MORNING BUT MAY INCREASE TO 10 TO 15 KNOTS LATER TODAY. THE SNOW COVER MAY KEEP THE AIR NEAR THE GROUND COLD ENOUGH TO MAINTAIN THE INVERSION. WE EXPECT THE WIND TO BECOME SOUTHWEST BY 04 UTC FRIDAY. THE SURFACE HIGH PRESSURE RIDGE WILL PASS OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA EARLY TONIGHT. &&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADV IN EFFECT THROUGH THIS AFTEROON.

&&

$$

.DISCUSSION MORNING GRIDS/ZONES... 445 AM CST

NO SIGNIFICANT CHANGES NECESSARY TO GOING FORECAST...AND NO MAJOR WX CONCERNS OVER THE NEXT SEVERAL DAYS.

SHORT WAVE TROUGH CROSSED THROUGH THE REGION OVERNIGHT AND IS NOW MOVING INTO THE LOWER LAKES AND UPPER OH VALLEY WITH SUBSIDENCE AND DRYING IN ITS WAKE CLEARING OUT CLOUDS FROM MOST OF WI AND IL. WITH CORE OF COLD AIR OVER THE ONTARIO/QUEBEC BORDER THE DEPTH OF REINFORCING COLD AIR ACROSS THE WESTERN GREAT LAKES IS RATHER SHALLOW. LAKE EFFECT SHOW QUICKLY DEVELOPED EARLIER THIS MORNING WITH THE WESTERN EDGE CLIPPING EASTERN PORTER COUNTY AS THE BOUNDARY LAYER FLOW HAS VEERED TO NNW. FORECAST TEMPERATURE PROFILE OVER SOUTHERN LAKE MI INDICATES TOPS OF LAKE EFFECT CLOUDS TO REACH TO AROUND 7K FT ALLOWING MODERATELY VIGEROUS SNOW SHOWERS. WINDS ALREADY BACK TO NW BY 18Z SHIFTING THE LAKE EFFECT OUT OF THE FA LIMITING THE TIME OF POSSIBLE ACCUMULATION. FAR NE PORTER MAY SEE 1-3 INCHES THIS MORNING.

SURFACE RIDGE CROSSES AREA THIS EVENING WITH INCREASING SW LOW LEVEL FLOW OVERNIGHT. THIS IN RESPONSE TO LOW PRESSURE DEEPENING AND MOVING ACROSS SASKATCHEWAN TO MANITOBA BY FRI MORNING AS STRONG SHORT WAVE MOVES SE FROM NORTHERN B.C. WAA AND UVV SPREAD E INTO THE NORTHERN LAKES OVERNIGHT AND INTO THE CENTRAL LAKES DURING THE DAY FRI. SNOW IN THE ZONE OF STRONG ISENTROPIC LIFT WILL PASS BY TO THE N AND NE OF THE LOCAL AREA. AS THE SHORT WAVE CONTINUES ESE TO LAKE SUPERIOR FRI NIGHT THE ASSOCIATED SURFACE LOW MOVE INTO THE CENTRAL LAKES AND A COLD FRONT PUSHES SE INTO THE FA DELIVERING MORE COLD AIR DEEPER ACROSS THE PLAINS AND MIDWEST. DEW POINTS TO CLIMB IN THE MID 20S ON THE SW FLOW AHEAD OF THE COLD FRONT AND WITH FROPA FRI NIGHT STRONG SHALLOW CAA SETS IN AND A PERIOD OF LIGHT FREEZING DRIZZLE POSSIBLE POST FROPA.

A COUPLE MORE WAVES TO DROP INTO THE UPPER TROUGH SAT AND SUN DEEPENING IT ACROSS THE OH VALLEY. THESE IMPULSES TO GENERATE ONLY SOME FLURRIES EXCEPT POTENTIAL FOR LAKE EFFECT TO MOVE BACK INTO FAR NW FOR SUN DEPENDING ON HOW MUCH THE LOW LEVEL FLOW VEERS. WITH COLD AIR AND RELATIVELY WARM LAKE WATERS A LOW PRESSURE TROUGH TENDS TO LAY OUT E-W ACROSS THE UPPER GREAT LAKES AND THIS MAY TEND TO KEEP SURFACE WINDS ON SOUTHERN LAKE MI FROM THE NW VS NNW.

WITH THE UPPER TROUGH AXIS OVER THE GREAT LAKES SUN INTO MID WEEK TEMPS WILL BE BLEOW NORMAL AFTER RUNNING NEAR NORMAL FRI AND SAT.

TRS

&&

.AVIATION... 616 AM CST

SOME VFR TO HIGH MVFR CLOUDS MAY MOVE INTO NORTH CENTRAL ILLINOIS THIS MORNING. A BAND OF CLOUDS WAS SEEN OVER WESTERN WISCONSIN THIS MORNING AT 11 AND 12 UTC. THE WIND FLOW IS FROM THE NORTHWEST AS SEEN ON THE PROFILER 850 MB WIND. WILL ADD A BROKEN VFR LAYER OVER RFD IN THIS MORNINGS FORECAST. THE ACARS SOUNDING SHOW A SHALLOW INVERSION AROUND 1330 FT AT RFD 848 UTC. THE WIND ABOVE THIS INVERSION INCREASES TO AROUND 30 KNOTS FROM THE NORTH. THE FORECAST WIND IS AROUND 9 KNOTS THIS MORNING BUT MAY INCREASE TO 10 TO 15 KNOTS LATER TODAY. THE SNOW COVER MAY KEEP THE AIR NEAR THE GROUND COLD ENOUGH TO MAINTAIN THE INVERSION. WE EXPECT THE WIND TO BECOME SOUTHWEST BY 04 UTC FRIDAY. THE SURFACE HIGH PRESSURE RIDGE WILL PASS OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA EARLY TONIGHT. &&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADV IN EFFECT FROM THIS EVENING THROUGH THURSDAY AFTERNOON.

&&

$$

.UPDATE... 12Z RAOBS/WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE TROF IN ERN NAMERICA DOWNSTREAM OF RDG OVER THE ROCKIES. LES CONTINUES OVER THE FA DOWNSTREAM OF LK SUP IN COLD N FLOW BTWN HI PRES IN NW ONTARIO AND LO PRES TROF EXTENDING FM LK HURON INTO CNTRL LK SUP. 12Z TAMDAR SDNG FM SAW SHOWS INVRN AT H825 WITH BASE TEMP A CHILLY -25C. RUC ANALYSIS SHOWS H85 THERMAL TROF OVER LK SUP ATTM. SPOTTER REPORT FM EBEN JUNCTION IN WRN ALGER COUNTY INDICATES 8 INCHES FELL THERE DURING THE NGT WHERE HEAVIER LES BAND LINGERED LONGER. REPORTS IN GOGEBIC COUNTY/ERN MQT COUNTY SHOW 4-6 INCHES ACCUMULATION. HOWEVER... THE OVERALL SHSN INTENSITY/COVG HAS BEEN DIMINISHED SOMEWHAT BY VERY DRY/STABLE AIR UPSTREAM OVER ONTARIO ASSOCIATED WITH THE ARCTIC HI PRES. SFC DWPTS -30F TO -40F WDSPRD OVER ONTARIO N OF LK SUP...AND 12Z TAMDAR SDNG FM YQT AS WELL AS RAOBS FM INL/YPL SHOW INVRN BASE H925-95 AND PWAT 0.05-0.10 INCH. IN FACT DESPITE LLVL CNVGC ALG TROF IN ALGER COUNTY BTWN NW LAND BREEZE FM THE W AND MORE NNE FLOW OVER THE E OFF ONTARIO...MQT 88D SHOWS LES BANDS HAVE BECOME RATHER DISORGANIZED WITH IMPACT OF DRY/STABLE ADVCTN AS WELL AS SOME DIRECTIONAL SHEAR IN THE SUB INVRN LYR DEPICTED ON MQT VWP. FEW REFLECTIVITIES ABV 20DBZ REMAIN. SHORTER FETCH/LAND BREEZE FLOW OFF ONTARIO HAVE PRETTY MUCH ENDED THE LES OVER THE FAR ERN CWA. SFC TEMP IN CHIPPEWA COUNTY HAS FALLEN TO ARND -10F WITH DRIER FLOW.

MAIN FCST CONCERNS TDAY INVOLVE LES TRENDS/ADDITIONAL AMTS/GOING HEADLINES.

FOR TDAY...GUIDANCE SHOWS HGT RISES BLDG HI PRES INTO THE UPR GRT LKS. ARRIVAL OF MORE ACYC FLOW/LOWER INVRN HGT WL DIMINISH THE LES W-E. IN FACT...EXPECT THE SHSN TO END OVER THE W AT IWD THIS AFTN AS LLVL FLOW BACKS TO THE SW. GOING FCST HAS THESE LARGE SCALE TRENDS WELL IN HAND...SO NEED TO MAKE ONLY MINOR ADJUSTMENTS TO FCST WX AND SN AMTS. WL ALLOW GOING HEADLINES TO CONT/EXPIRE AS FCST. EXCEPT TO BUMP UP FCST HI TEMPS AT A FEW PLACES MAINLY NR LK SUP BASED ON CURRENT TEMPS...ONLY A FEW TWEAKS NECESSARY TO GOING MAX TEMPS FCST.

KC

.PREVIOUS DISCUSSION (ISSUED AT 404 AM)... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING FROM SOUTHERN CALIFORNIA INTO NORTHERN ALBERTA WHILE UPPER TROUGHING DOMINATED SE CANADA INTO THE GREAT LAKES. WITHIN THIS TROUGH...A SHRTWV CAN BE SEEN DIVING SOUTHWARD THROUGH NORTHERN ONTARIO...NOW NEAR WAWA. 850MB TEMPS ASSOCIATED WITH THIS SHRTWV APPEAR TO BE AROUND -25C BASED ON 00Z RAOBS FROM MOOSONEE AND PICKLE LAKE. ALTHOUGH THE AIR IS QUITE COLD WITH THE SHRTWV...VERY LITTLE IS OCCURRING ON IR IMAGERY WITH IT DUE TO THE PRESENCE OF VERY DRY AIR (PRECIPITABLE WATER OF 0.04 INCHES ON THE PICKLE LAKE SOUNDING). SURFACE TEMPERATURES AND DEWPOINTS ALSO DEPICT THE SAME STORY OVER NORTHERN ONTARIO...WITH READINGS WELL BELOW ZERO F. THE COLD AND DRY AIR CONTINUES TO FLOW ACROSS LAKE SUPERIOR ON NORTHERLY WINDS BETWEEN A 1032MB HIGH OVER NW ONTARIO AND A LOW PRESSURE TROUGH THAT EXTENDS FROM LAKE ERIE TO SOUTHERN WISCONSIN. A LAKE INDUCED TROUGH ALSO EXTENDS FROM LAKE ERIE NW TO NEAR ONTONAGON. PLENTY OF LAKE EFFECT SNOW SHOWERS EXIST DUE TO THE COLD AIR FLOWING OVER 2-3C WATER TEMPS. CURRENT RADAR IMAGERY SHOWS A FEW DISORGANIZED BANDS IN ALGER AND EASTERN MARQUETTE COUNTIES...THOUGH THERE ARE A FEW 28DBZ PIXELS WITHIN THEM. THERE WERE ALSO SOME INTENSE BANDS OCCURRING IN THE FAR WESTERN U.P. OVERNIGHT...WITH THE BESSEMER AREA PICKING UP AROUND 6 INCHES SINCE 7 PM CST PER THE COUNTY SHERIFF. HOWEVER... OVER THE PAST FEW HOURS...THE SATELLITE APPEARANCE HAS GREATLY DIMINISHED FOR THE LAKE EFFECT BANDS ON WESTERN LAKE SUPERIOR. TO OUR NW...A 130 KT JET STREAK IS MOVING THROUGH WESTERN ONTARIO. UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION IS HELPING SUPPORT MID/HIGH CLOUDS OVER NORTHERN MANITOBA. THESE CLOUDS ARE ALSO ASSOCIATED WITH A STRONG SHRTWV TROUGH WHICH CAN BE SEEN MOVING ACROSS NORTHERN BRITISH COLUMBIA.

&&

.DISCUSSION... MAIN FORECAST CONCERNS ARE WARM ADVECTION SNOW TONIGHT/FRI AND LES EVENT FOR FRI NIGHT/SAT.

TODAY...SHRTWV NEAR WAWA WILL CONTINUE TO MAKE ITS WAY SOUTHWARD IN THE MAINLY NORTHERLY FLOW ALOFT...REACHING SOUTHERN LAKE HURON BY 18Z. AS THIS SHRTWV PASSES...IT WILL CAUSE THE HIGH PRESSURE AREA OVER NW ONTARIO TO BE PULLED DOWN INTO THE CWA BY 00Z. THEREFORE... LES SHOULD BE ON A DIMINISHING TREND. IN FACT...THE LES IS EXPECTED TO END IN THE WESTERN U.P. DUE TO A COMBINATION OF A CRASHING INVERSION AND STRONG DRY AIR ADVECTION...DESPITE LAKE SURFACE TO 850MB DELTA-TS REMAINING AT OR ABOVE 16C. CURRENT LES TRENDS ON WESTERN LAKE SUPERIOR SUPPORT THIS ASSESSMENT TOO. FOR THE NORTH CENTRAL U.P....THE ENDING TREND WILL BE DOMINATED BY THE WIND DIRECTION SINCE DELTA-TS ARE PROGGED AT OR ABOVE 20C AND THE LONGER FETCH OF EASTERN LAKE SUPERIOR WILL MITIGATE THE MOISTURE. HOWEVER...THE LAKE EFFECT WILL NOT BE AS GREAT AS IT WAS YESTERDAY OR LAST NIGHT. WITH 850MB TEMPS REMAINING CHILLY...ONLY WARMING TO -14C WEST OT -20C EAST...WILL CONTINUE TO STAY ON THE LOW END OF GUIDANCE FOR TEMPS.

AS FAR AS HEADLINE CHANGES...DROPPED ADVISORY FOR SOUTHERN SCHOOLCRAFT AS LITTLE IN THE WAY OF SNOWFALL APPEARS TO HAVE OCCURRED THERE OVERNIGHT PER RADAR IMAGERY. ALL OTHER HEADLINES WILL CONTINUE TO THEIR EXPIRATION TIMES.

TONIGHT...SHRTWV TROUGH CURRENTLY OVER NORTHERN BRITISH COLUMBIA IS PROGGED TO DROP SE TO LAKE WINNIPEG BY 12Z FRI...WITH A 997MB LOW OR SO LOCATED NEAR THE NE END. AS THIS OCCURS...A PORTION OF THE WESTERN RIDGE WILL COME DOWN AHEAD OF THE TROUGH...CAUSING THE HIGH PRESSURE AREA OVER UPPER MICHIGAN TO SLIDE EASTWARD. WARM ADVECTION ON THE BACK SIDE OF THE HIGH/AHEAD OF THE SHRTWV TROUGH...COMBINED WITH UPPER DIVERGENCE ASSOCIATED WITH THE 130KT JET STREAK CURRENTLY IN MANITOBA MOVING TO LAKE HURON...WILL CAUSE A BAND OF MID CLOUDS TO MOVE INTO THE CWA. INITIALLY...DRY LOW LEVELS SHOULD PREVENT PCPN. HOWEVER...CONTINUED ISENTROPIC LIFTING/FRONTOGENETICAL FORCING WILL CAUSE BASES TO LOWER AFTER MIDNIGHT...AND SOME LIGHT SNOW IS EXPECTED TO DEVELOP. THERE STILL REMAINS SOME DISAGREEMENT ON THE DEVELOPMENT OF THIS SNOW...THOUGH...AS NOTED BY NAM SOUNDINGS WHICH SUGGEST THE DRIER LOW LEVELS WILL STAY FIRMLY IN PLACE. GIVEN THIS DISAGREEMENT...AM HESITANT TO GO LIKELY YET...THOUGH WITH THE CONSISTENCY OF THE GFS AND A LOCAL WRF-ARW RUN SHOWING A SIMILAR SCENARIO TO THE GFS...FEEL AN UPGRADE TO 50 POPS IS WARRANTED. TEMPERATURES ARE STILL TRICKY GIVEN THAT THERE WILL BE A FEW HOURS IN THE EVENING WITH ONLY SOME HIGH CLOUDS AROUND. GOING FORECAST MINS LOOK REASONABLE. READINGS SHOULD CLIMB AFTER MIDNIGHT WITH RETURN FLOW AND INCOMING WARM ADVECTION PCPN.

FRI...SHRTWV TROUGH WILL CONTINUE MOVING SE...REACHING MINNESOTAS INTERNATIONAL BORDER AROUND 00Z. THE SURFACE LOW ASSOCIATED WITH THE TROUGH IS PROGGED TO MOVE INTO THE WESTERN U.P.. BAND OF WARM ADVECTION SNOW WHICH IS EXPECTED OVER THE WEST HALF OF THE U.P. IN THE MORNING WILL PUSH EAST THROUGH THE DAY...PERHAPS GETTING ENHANCED BY A LAKE MICHIGAN LAKE EFFECT BAND. BEHIND THE WARM ADVECTION SNOW...A DRY SLOT IS PROGGED TO COME IN ALOFT. SOME CONCERN EXISTS THAT THE SNOW MAY TAPER OFF TO FREEZING DRIZZLE...BUT RIGHT NOW THE -10C LAYER STILL REMAIN SATURATED...SO THE SNOW MAY JUST TO TAPER OFF TO FLURRIES OR NOTHING AT ALL. FOR NOW WILL MAINTAIN A CHANCE OF SNOW INTO THE AFTERNOON...BUT HAVE MUCH LOWER QPF VALUES THEN. HAVE RAISED TEMPERATURES SLIGHTLY IN THE WESTERN U.P. GIVEN THAT GUIDANCE HAS WARMED UP IN THIS AREA. OTHERWISE...THE REST OF THE HIGH TEMP FORECAST LOOKS REASONABLE.

FRI NIGHT AND SAT...DURING THIS PERIOD...THE SHRTWV TROUGH IS PROGGED BY ALL MODELS TO SWING THROUGH THE CWA. COLD AIR ADVECTION AT 850MB SHOULD ALREADY BE GOING ON FRI EVENING...WITH 850MB TEMPS FALLING TO -12 TO -14C BY 06Z...WHICH SHOULD BE ENOUGH TO GET LAKE EFFECT GOING...ESPECIALLY IN THE WESTERN U.P. GIVEN THE PROGGED WNW LOW LEVEL WIND FLOW. LAKE EFFECT WILL ALSO GET SOME SYNOPTIC SUPPORT DUE TO DPVA AHEAD OF THE SHRTWV TROUGH. HAVE INCLUDED A FEW INCHES OF SNOWFALL...HOWEVER IF THE TROUGH COMES IN FASTER...AT LEAST ADVISORY LEVEL SNOWFALL SHOULD BE MET FOR FRI NIGHT. SINCE IT LOOKS CERTAIN THAT SOME LAKE EFFECT WILL OCCUR IN THE WESTERN U.P....HAVE RAISED POPS TO CATEGORICAL. THINGS GET A LITTLE MORE INTERESTING ON SAT. ON SAT...AS THE SHRTWV TROUGH AND ITS ACCOMPANYING MID-LEVEL MOISTURE MOVES ACROSS...A SECONDARY SURFACE COLD FRONT ASSOCIATED WITH THE SHRTWVS SURFACE LOW IS PROGGED TO DROP SOUTH ACROSS LAKE SUPERIOR. GIVEN THAT 850MB TEMPS COOL A FEW MORE DEGREES C... RESULTING IN PLENTY OF OVER-WATER INSTABILITY...THERE WILL LIKELY BE A SIGNIFICANT CONVERGENT LAKE EFFECT BAND ALONG THE FRONT. WOULD NOT BE SURPRISED TO SEE A COUPLE OF INCHES OF SNOW FALL OUT OF THIS BAND ACROSS ALL OF THE NORTHERN U.P.. GFS FORECAST SOUNDINGS ARE PRETTY IMPRESSIVE WHEN THE BAND COMES THROUGH...INDICATING SATURATED CONDITIONS UP TO 15000 FT AND THE ONLY INVERSION BEING THAT OF THE TROPOPAUSE. IN ADDITION...NORTHERLY WINDS BEHIND THE FRONT...ALONG WITH PLENTY OF LOW TO MID LEVEL MOISTURE AROUND SHOULD SUPPORT MORE INTENSE MULTI-PARALLEL BANDS THAN THOSE TODAY. GIVEN THE CONSISTENCY FROM THE MODELS PREDICTING THIS EVENT...HAVE INCREASED POPS TO CATEGORICAL. IN FACT...HAVE EVEN INCLUDED THE WORDING OF HEAVY AT TIMES FOR THE FAR WESTERN U.P. AS THIS AREA WILL SEE STRONG LOW LEVEL CONVERGENCE ALL DAY. HAVE ADJUSTED QPF/SNOW AMOUNTS UPWARD TO NEAR WARNING CRITERIA FOR THE FAR WESTERN U.P. WITH THE REST OF THE NORTHERN U.P. AT ADVISORY LEVEL. FOR NOW...THE EVENT WILL CONTINUE TO BE HIGHLIGHTED IN THE HWO...BUT FUTURE SHIFTS WILL LIKELY NEED TO ISSUE WATCHES...WARNINGS AND/OR ADVISORIES.

SAT NIGHT AND SUN...GFS/UKMET/ECMWF INDICATE THAT AFTER THE PASSAGE OF SATURDAYS SHRTWV TROUGH...ANOTHER SHRTWV WILL DIVE SOUTHWARD THROUGH MINNESOTA AND INTO ILLINOIS. MOISTURE ASSOCIATED WITH THIS SHRTWV LOOKS TO STAY TO THE WEST OF HERE...THEREFORE WITH 850MB TEMPS COOLING INTO THE LOW -20S C...DRY AIR ADVECTION AND LOWERING INVERSIONS...THE LAKE EFFECT SNOW WILL BE ON A DIMINISHING TREND THROUGH THIS PERIOD. OTHERWISE...WITH THE COOLER 850MB TEMPS...READINGS WHICH WILL BE CLOSE TO NORMAL FOR FRI AND SAT WILL GO BACK TO BELOW NORMAL.

BEYOND SUN...LOOKS LIKE THE PATTERN WILL REMAIN COLD WITH PERIODS OF LAKE EFFECT SNOW. LOOKING FARTHER OUT TOWARDS THE BEGINNING OF FEBRUARY...THERE HAS BEEN A LOT OF CONSISTENCY WITH PAST GFS AND ECMWF RUNS...INCLUDING THOSE TODAY...SUGGESTING A COLDER ARCTIC AIRMASS TO MOVE INTO THE CWA WITH 850MB TEMPS AROUND THE -30C MARK. WILL WAIT AND SEE IF THIS OCCURS...BUT GIVEN THE CONSISTENCY...IT BEARS WATCHING.

COORD WITH GRB AND HPC...THANKS.

AJ

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FOR MIZ006 UNTIL 22Z. LAKE EFFECT SNOW ADVISORY FOR MIZ005-013 UNTIL 18Z. LAKE EFFECT SNOW ADVISORY FOR MIZ002-009 UNTIL 12Z. LAKE EFFECT SNOW ADVISORY FOR MIZ085 UNTIL 22Z.

&&

$$

.SYNOPSIS...HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL CONTINUE MOSTLY CLEAR SKIES INTO FRIDAY. COOLER FRIDAY AS ONSHORE FLOW RETURNS. UPPER LEVEL LOW PRESSURE WILL BRING COOLER DAYS WITH A RETURN OF COASTAL LOW CLOUDS AND FOG IN THE NIGHTS AND MORNINGS ALONG WITH VARIABLE HIGH CLOUDINESS THIS WEEKEND AND EARLY NEXT WEEK.

&&

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

.SHORT TERM (TODAY-SUN)...CLEAR SKIES TODAY. ACARS SOUNDINGS HAD WEAK ELY WIND THROUGH MOST OF THE COLUMN. WEAK OFFSHORE GRADIENTS WITH ABOUT -5 MB SAN-TPH AND -2 SAN-IPL.

THE OFFSHORE FLOW WILL STILL CAUSE LOCAL BREEZY CONDITIONS LATE THIS AFTERNOON AND EARLY EVENING...MAINLY IN AND NEAR THE SAN DIEGO AND RIVERSIDE COUNTY MOUNTAINS. CONTINUED FAIR BUT A LITTLE COOLER IN MOST AREAS FRI AS HEIGHTS BEGIN TO LOWER AND ONSHORE FLOW INCREASES. A WEAK UPPER LOW WILL UNDERCUT THE HIGH AMPLITUDE RIDGE NEAR THE W COAST THIS WEEKEND. AN EDDY IS EXPECTED TO DEVELOP LATE FRI NIGHT WITH A RETURN OF MARINE LAYER CLOUDS. LOW CLOUDY MAY START MOVING ONSHORE FRI AFTERNOON. THERE COULD BE LOCAL DENSE FOG IN THE COASTAL AREAS AND FAR WRN SAN DIEGO INLAND VALLEYS FRI NIGHT AND SAT MORNING. THE MARINE LAYER WILL CONTINUE TO DEEPEN INTO SUN BUT BUT MAY BE BROKEN UP A BIT BY INCREASING HIGH CLOUDINESS. COOLER DAYS. HIGHER HUMIDITIES AND MORE CLOUDS WILL MODERATE MIN TEMPS W OF THE MOUNTAINS.

.LONG TERM (MON-THU)...PROGS CONTINUE TO DISAGREE ON THE DETAILS BUT GENERALLY INDICATE WEAK TROUGHING OVER THE SW EARLY NEXT WEEK. THIS SHOULD BRING VARIABLE CLOUDINESS WITH A SMALL CHANCE OF LIGHT PRECIP. HOWEVER...TOO MUCH UNCERTAINTY TO MENTION PRECIP IN THE FORECAST YET. COOL DAYS BUT STILL MILD AT NIGHT W OF THE MOUNTAINS. BUILDING HIGH PRESSURE AND OFFSHORE FLOW SHOULD RETURN TOWARD THU OF NEXT WEEK.

&&

.AVIATION... WEAK OFFSHORE FLOW WILL CONTINUE VFR CONDITIONS THROUGH FRIDAY MORNING WITH A CLEAR SKY AND UNRESTRICTED VISIBILITIES. SOME WINDS IN SOUTHERN SAN DIEGO COUNTY MAY CAUSE LOCAL TURBULENCE AND LLWS THIS AFTERNOON. WEAK ONSHORE FLOW IS EXPECTED TO RETURN TO THE COAST FRIDAY AFTERNOON WHICH COULD BRING SOME STRATUS/FOG BACK TO THE COASTAL AIRPORTS FRIDAY EVE.

&&

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

&&

$$

PUBLIC...DVA AVIATION...MM

.SHORT TERM DISCUSSION (TONIGHT)... 12Z RAOBS/WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE TROF IN ERN NAMERICA DOWNSTREAM OF RDG OVER THE ROCKIES. LES OVER THE FA DOWNWIND OF LK SUP IN COLD NW FLOW BTWN ARCTIC HI PRES OVER ONTARIO AND LO PRES IN THE LOWER GREAT LKS IS ON THE DIMINISHING TREND AS VERY DRY/STABLE AIR SHOWN ON UPSTREAM 12Z RAOBS/TAMDAR SDNG FM CYQT (INVRN BASE H925-95 AND PWAT AS LO AS 0.05 INCH) MOVES OVER THE UPR LKS UNDER BLDG H5 HGTS/ INCRSG LARGER SCALE ACYC FLOW DESPITE SOME LINGERING CNVGC ALG LK INDUCED TROFFING EXTENDING FM LO TO THE SE NW ACRS LK HURON INTO ALGER COUNTY/CNTRL LK SUP. UPSTREAM...A SHRTWV MOVING INTO NRN ALBERTA/SASKATCHEWAN IS TOPPING THE ROCKIES RDG. QUITE A BIT OF MID CLD AND EVEN SOME PTCHY -SN NOTED FM SCNTRL CAN INTO NE ND/NW MN IN THE SW FLOW/WAD PATTERN BTWN LO PRES ASSOCIATED WITH THIS SHRTWV AND THE HI PRES SYS OVER ONTARIO AND THE UPR MS RIVER VALLEY. PWAT 0.44 INCH AT YQD...SO THERE IS MORE MSTR AVBL TO THIS SHRTWV.

MAIN FCST CONCERNS IN THE SHORT TERM ARE LINGERING LES TRENDS AND -SN CHCS ASSOCIATED WITH SHRTWV NOW TOPPING ROCKIES RDG.

FOR TNGT...GUIDANCE SHOWS RISING HGTS OVER THE UPR GRT LKS IN ADVANCE OF SHRTWV NOW OVER NRN ALBERTA/SASKATCHEWAN...WHICH IS FCST TO REACH NR LK WINNIPEG BY 12Z FRI. AS HGTS RISE AND SFC RDG AXIS/ LOWER INVRN BASE/DEEPER DRY AIR PASSES ACRS THE CWA THIS EVNG UNDER THE RISING HGTS...EXPECT LES TO DIMINISH AND THEN END WITH LTL ADDITIONAL ACCUMULATION. WL LET ANY GOING HEADLINES EXPIRE AS SCHEDULED. ALTHOUGH SKIES WL BE PCLDY FOR A TIME WITH ARRIVAL OF RDG AXIS (EXCEPT OVER THE KEWEENAW WITH BKN-OVC SC LINGERING IN W-SW FLOW EVEN ON BACK SIDE OF RDG)...NAM/GFS SHOW ISENTROPIC LIFT ON THE 280-290K SFCS OVERSPREADING THE FA QUICKLY AS SW RETURN FLOW DVLPS IN THE WAKE OF DEPARTING SFC RDG. GFS IS MOST AGGRESSIVE AT PUSHING HIER MID LVL MSTR TO THE E...AND USED ITS 280K SFC RH AOA 70 PCT TO TIME ARRIVAL OF MID CLD AS THIS PROG APPEARS TO CORRELATE WELL WITH OBSVD HI SC/LO AC CLD UPSTREAM. NAM FCSTS LLVLS BLO THE MID CLD DECK REMAINING SO DRY THAT MODEL QPF IS ZERO...BUT GFS GENERATES SOME LGT PCPN UNDER THE STRONGER ISENTROPIC LIFT AFT ABOUT 03Z OR SO OVER THE W AND ACRS THE ENTIRE CWA AFT 06Z WITH ARRIVAL OF UPR DVGC IN RRQ OF H3 JET MAX FCST TO MOVE OVER SE ONTARIO BY 12Z FRI. GFS FCST SDNGS ARE QUITE A BIT MORE MOIST THRU MOST OF THE TROP IN LINE WITH OBSVD 12Z YQD SDNG...BUT MODEL FCST SDNGS DO SHOW LINGERING DRY LYR BTWN H75-55...WHICH WOULD ALSO BE THE PRIME DENDRITIC SN GROWTH LYR. CONSIDERING THIS DRY LYR AS WELL AS ANTECEDENT DRY AIR...LIMITED COVG OF OBSVD SN UPSTREAM...AND NAM FCST...HAVE OPTED TO RETAIN POPS BUT CUT VALUES FM HI CHC TO LWR CHC IN LINE WITH GFS MOS GUIDANCE. AS FOR TEMPS...EXPECT MIN TEMPS RELATIVELY EARLY BEFORE THICKER MID CLD/A BIT STRONGER SW FLOW DVLPS W-E AFT EARLY THIS EVNG.

KC

.LONG TERM (FRIDAY THROUGH THURSDAY)... THE MAIN FORECAST CONCERN FOR THIS PORTION OF THE FORECAST REMAINS THE LAKE EFFECT SNOW EVENT FOR LATE FRIDAY NIGHT THROUGH MUCH OF THE WEEKEND.

ONCE AGAIN FOR THIS PERIOD...AM GENERALLY DISCOUNTING THE NAM...AS IT IS OUT OF BOUNDS WHEN COMPARED TO THE GLOBAL MODELS. AS A RESULT...HAVE LEANED THIS FORECAST CLOSER TO THE GFS SOLUTION.

GFS OFF OF BUFKIT IS PUTTING OUT OVER HALF AN INCH OF QFP OVER IWD DURING THE NEXT 5 DAYS. CONTINUE TO MONITOR THE TRACK OF THE SURFACE LOW...CURRENTLY CENTERED OVER THE SOUTHERN NORTHWEST TERRITORIES SLIDING INTO NORTHERN SASKATCHEWAN. THIS LOW WILL SLIDE SOUTHEASTWARD...AND OVER THE WESTERN HALF OF LAKE SUPERIOR BY FRIDAY AFTERNOON AND THEN SOUTHEASTWARD OVER LAKE HURON BY 12Z SATURDAY. THIS WILL FIRST ALLOW FOR A LONG SOUTHERLY FETCH ACROSS LAKE MICHIGAN LATE FRIDAY MORNING THROUGH EARLY AFTERNOON (GENERALLY 2 TO 4 INCHES OF SNOW EXPECTED ACROSS THIS AREA FRIDAY)...AND THEN SWING THE WINDS OUT OF A GENERALLY NORTH TO NORTHWESTERLY DIRECTION FRIDAY NIGHT (AND KEEP THEM BETWEEN 300 AND 030 THROUGH TUESDAY). 850MB TEMPERATURES...AFTER WARMING TO -7C OR SO FRIDAY WILL COOL DOWN TO -12C ACROSS THE AREA BY 12Z SATURDAY...ALLOWING FOR A BETTER CHANCE OF LAKE EFFECT OR LAKE ENHANCED SNOW. 850MB TEMPERATURES WILL THEN SLOWLY COOL TO -20 TO -22C BY 06Z SUNDAY. GIVEN THIS...HAVE HOISTED LAKE EFFECT SNOW WATCHES FOR GOGEBIC...ONTONAGON...MARQUETTE...AND ALGER COUNTIES FOR SATURDAY MORNING THROUGH MID DAY SUNDAY.

FOR FRIDAY NIGHT HAVE ADJUSTED TEMPS DOWN A COUPLE OF DEGREES ACROSS OUR CLIMATOLOGICALLY COOLER SOUTH CENTRAL CWA...WITH THE IDEA THAT THE DRY SLOT MAY COME IN EARLY AND ALLOW TEMPS TO DROP. FIRST COLD FRONT IS EXPECTED TO CROSS THE CWA LATE FRIDAY AFTERNOON THROUGH 06Z SATURDAY. COOLER TEMPS ALOFT WILL TAKE A BIT LONGER TO SLIDE IN.

EXPECT THE SINGLE DIGITS TO LOW TEENS FOR HIGH TEMPERATURES SUNDAY...AS THE COLDEST AIR SINKS OVERHEAD. WINDS BACK SLIGHTLY SUNDAY...ADDING TO THE CONVERGENCE OVER THE EASTERN THIRD OF THE LAKE SUPERIOR SHORELINE FROM MUNISING EAST. AS HAS BEEN THE TREND OVER THE LAST COUPLE OF SHIFTS...HAVE INCREASED POPS HERE TO DEFINITE. AS FOR RIGHT NOW...DO NOT HAVE ANY WATCHES/WARNINGS OR ADVISORIES POSTED FOR THE EASTERN PORTIONS OF THE CWA (EXCEPT ALGER COUNTY)...BUT AS THE TIME NEARS HEADLINES WILL LIKELY BE NEEDED.

MONDAY THROUGH THURSDAY (DAYS 4-7)...WITH THE RELATIVE CONSISTENCY IN THE EXTENDED RANGE...WITH LESS MODEL FLIP FLOPPING THAN USUAL...FEW CHANGES WERE MADE...PARTICULARLY TO TEMPERATURES. STILL...DID COOL DOWN TEMPERATURES ROUGHLY 4 DEGREES ACROSS THE BOARD MONDAY AFTERNOON. SO THE OVERALL PATTERN INCLUDES A SERIES OF SHORTWAVES IN THE POLAR/ARCTIC JET CONTINUALLY RE-ENFORCING OUR ALREADY COLD AIRMASS.

MONDAY 12Z...LOOKING AT THE MID LEVELS...THE GFS AND ECMWF BEGIN TO BECOME A LITTLE MORE NOTICEABLE IN THERE DIFFERENCES. THE 500MB DEPICTED BY THE GFS...ALTHOUGH SIMILAR IN STRENGTH IS ABLE TO SLIDE FURTHER SOUTHWARD...MAKING IT INTO EASTERN LAKE HURON BY THIS TIME...WHILE THE ECMWF HAS IT REMAINING OVER EASTERN HUDSON BAY. AS PREVIOUSLY STATED...GENERALLY DISREGARDED THIS DISCREPANCY...AND SIDED CLOSER TO THE GFS SOLUTION. UPDATED AND INCREASED CLOUD COVER FOR MONDAY INTO MONDAY NIGHT...AS SHORTWAVE SLIDES IN FROM THE NORTHWEST...ACCORDING TO THE 06Z GFS. ALTHOUGH IT SEEMS THAT THE SHORTWAVE HAS DROPPED FURTHER SOUTH FOR THE 12Z GFS RUN...STILL BELIEVE THAT WE WILL HAVE MORE THAN 40 PERCENT CLOUD COVER FOR THIS PERIOD...SO HAVE KEPT THE ADJUSTED MORE PESSIMISTIC CLOUD FOR MONDAY INTO MONDAY NIGHT.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR MIZ005-006.

LAKE EFFECT SNOW WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING FOR MIZ002-009.

&&

$$

.SHORT TERM...KC .LONG TERM...KF