Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 01/16/07


AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 146 AM EST SUN JAN 14 2007

.AVIATION... PATCHY FREEZING DRIZZLE WILL PERSIST THIS MORNING WITH AREAS OF FREEZING RAIN DEVELOPING AS A WEAK UPPER LEVEL SYSTEM MOVES INTO THE AREA. EXPECT ONLY A SLIGHT TEMPERATURE INCREASE TODAY...BUT JUST ENOUGH FOR FWA TO RISE ABOVE FREEZING. HAVE KEPT SBN AT OR BELOW FREEZING...SO HAVE INCLUDED FREEZING DRIZZLE AND FREEZING RAIN THERE. NOT MUCH OF A CHANCE FOR CIGS TO IMPROVE OUT OF THE IFR CATEGORY AS THE FRONT REMAINS SOUTH OF THE AREA AND AS MOISTURE CONTINUES TO SPREAD NORTH OVER THE FRONT.

&&

.UPDATE... UPDATED ZONES/GRIDS TO ADD MENTION OF PRECIP THIS EVE. HAVE SEEN A COUPLE WAVES OF DRIZZLE MOVE THROUGH THE AREA LATE THIS AFTN AND THIS EVE AS WK TROFS MOVG THROUGH THE FLOW PROVIDING SLIGHT ENHANCEMENT TO THE GENERAL OVER-RUNNING PATTERN IN PLACE. MORE SGFNT PRECIP OVER WEST CENTRAL IL HAS BEEN DIMINISHING AS IT MOVES NE THIS EVE AND 00Z SOUNDINGS ARE SHOWING SOME MID LEVEL DRYING HAS OCCURRED TODAY OVER OUR AREA. 00Z NAM SUGGESTS DEEPER MOISTURE AND PRECIP ASSOCIATED WITH SHRTWV SEEN ON WATER VAPOR LOOP MOVG THROUGH MO MAY NOT REACH US UNTIL CLOSE TO DAYBREAK. HWVR, WITH A COUPLE OF WAVES OF FREEZING DRIZZLE ALREADY MOVG THROUGH THE AREA, THINK IT`S LIKELY THAT MORE OF THIS LIGHT FREEZING PRECIP WILL OCCUR OVERNIGHT SO WILL HOLD ONTO THE ADVISORY ISSUED EARLIER FOR LATE TONIGHT AND SUNDAY, THOUGH ATTM APPEARS THE MOST SGFNT PRECIP DURING THIS ADVISORY MAY HOLD OFF UNTIL SUNDAY MORNING.

&&

.SHORT TERM... TONIGHT AND SUNDAY

WILL SIDE MORE WITH THE 12Z NAM-WRF THAN THE 12Z GFS FOR THIS FORECAST PACKAGE. THE THERMAL PROFILES SEEM MORE PLAUSIBLE THAN THE GFS AS SEEN BY MOST CURRENT TAMDAR DATA.

AT 19Z...SFC ANALYSIS DEPICTED A NEARLY STATIONARY FRONTAL BOUNDARY NEAR THE OHIO RIVER. THIS FRONT WILL UNDULATE SOME OVER THE NEXT 24 HOURS AS WAVES OF SFC LOW PRESSURE RIPPLE NE ALONG IT. MEANWHILE...ARCTIC HIGH PRESSURE WAS SPRAWLED FROM ONTARIO WESTWARD INTO THE UPR MS RIVER VLY. COLDER AIR HAS MADE ITS WAY INTO THE NRN THIRD OF THE FCST VIA SFC NE FLOW. THE FORECAST DILEMMA FOR TONIGHT INTO SUNDAY WILL BE HOW FAR SOUTH THE FREEZING LINE WILL MOVE AND HOW THIS WILL AFFECT PCPN TYPE.

FOR TONIGHT...A TANDEM OF UPR LVL S/WVS WILL ROTATE NE INTO THE WRN GREAT LAKES AND OHIO VLY REGION FROM THE SRN PLAINS/LOWER MS RIVER VLY. THESE S/WVS WILL PROVIDE UPR SUPPORT FOR VERTICAL LIFT. IN ADDITION...MODELS INDICATE THAT WARM...MOIST ISENTROPIC LIFT WILL DEVELOP TONIGHT...CONTINUING INTO SUNDAY. THE COMBINATION OF THE LIFT FROM THE S/WVS AND THE LIFT FROM MOIST...WARM AIR ADVECTION WILL CAUSE PCPN TO BREAK OUT FROM W TO EAST OVERNIGHT. WITH TEMPS AT OR BELOW FREEZING ACRS THE NRN TWO THIRDS OF THE FCST AREA AND WITH A WARM TONGUE OF AIR EXPECTED ALOFT...PCPN WILL FALL IN THE FORM OF FREEZING RAIN AND SLEET. ICE ACCUMULATIONS FROM THE FREEZING RAIN WILL BE ON THE LIGHT SIDE OVERNIGHT...MEASURING 0.05 OF AN INCH OR LESS. HOWEVER...ANY ICE WILL BE A HAZARD TO TRAVEL. HENCE...WILL ISSUE WINTER WX AND FREEZING RAIN ADVISORIES FOR TONIGHT STARING AFTER MIDNIGHT. ON SUNDAY...THERE MAY BE A BRIEF LULL IN THE PCPN BY AFTN AS AFOREMENTIONED S/WVS PIVOT OFF TO THE NE. HOWEVER...ANOTHER DISTURBANCE AND STRONGER WAVE OF LOW PRESSURE WILL APCH THE OHIO VALLEY BY EARLY EVENING...SPREADING WIDESPREAD PCPN BACK INTO THE REGION. KEEPING THIS IN MIND...HAVE DECIDED TO KEEP LIKELY POPS FOR THE ENTIRE PERIOD. TEMPERATURES WILL ONLY WARM SLIGHTLY DURING THE DAY...PERHAPS 3 TO 5 DEGREES FROM MORNING LOWS. ANY FREEZING RAIN BY AFTN WILL PROBABLY NOT ACCUMULATE MUCH WITH TEMPS HOVERING IN THE 32 TO 34 DEGREE RANGE. TO KEEP HEADLINES SOMEWHAT SIMPLISTIC WILL EXTEND THE ADVISORY THROUGH THE ENTIRE DAY AS ICING WILL LIKELY OCCUR DURING THE MORNING HOURS (ANOTHER 0.05 OF AN INCH). ALSO...THIS WILL MATCH UP WITH THE LONG TERM FORECASTER/S PLAN TO ISSUE A WINTER STORM WATCH FOR THE SUNDAY NIGHT/MONDAY TIME FRAME DUE TO THE NEXT WEATHER SYSTEM TO AFFECT THE REGION.

&&

.LONG TERM... SUNDAY NIGHT THROUGH SATURDAY

VERY CHALLENGING LONG TERM WITH THE FOCUS CONTINUING TO LIE WITH POTENTIAL MAJOR MIXED PRECIP EVENT AT THE START OF THE PERIOD. WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A WELL DEVELOPED MID/UPPER LEVEL TROUGH AND EMBEDDED CLOSED CIRCULATION OVER THE WESTERN CONUS. A DEEP PLUME OF SUB-TROPICAL MOISTURE EMANATING FROM THE LOW LATITUDES OF THE PACIFIC STRETCHES INTO THE CENTRAL CONUS IN ADVANCE OF THE WESTERN TROUGH WITH PWAT SOME 2-3 STDEV ABOVE NORMAL FOR JAN. THIS WILL SET THE STAGE FOR YET ANOTHER SIGNIFICANT QPF EVENT...ONLY THIS TIME THERE WILL BE A LOW LEVEL ARCTIC AIRMASS ATTEMPTING TO UNDERCUT THE CONTINUED WARM/MOIST SW FLOW ALOFT.

SIMILAR TO MIDNIGHT SHIFT...HAVE LEANED TOWARDS THE STRONGER AND FARTHER NW SOLUTION OF THE NAM OVER THE FLATTER AND SUPPRESSED GFS SOLUTION. THE NAM HAS SUPPORT FROM BOTH THE CANADIAN REGIONAL GEM AND THE UKMET FOR THE PAST SEVERAL RUNS. ON SUNDAY SHORTWAVE ENERGY AND ASSOCIATED HEIGHT FALLS EJECTING OUT OF MEAN WESTERN CONUS TROUGH WILL SPAWN ANOTHER SURFACE WAVE ALONG THE BAROCLINIC BOUNDARY STRETCHING FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY. BOTH NAM/GFS SHOW RAPIDLY STRENGTHENING UPPER LEVEL JET ACROSS THE GREAT LAKES SUN NGT IN ADVANCE OF TROUGH EJECTION WITH AREA OF STRONG UPPER LEVEL DIVERGENCE DEVELOPING WITHIN THE RIGHT ENTRANCE REGION OVER THE CWA. THE UPPER LEVEL SUPPORT COUPLED WITH LOW LEVEL ISENTROPIC ASCENT/THETA-E ADVECTION SHOULD SUPPORT A BROAD AREA OF LIFT SUN NGT INTO MON AM. GIVEN THE ANOMALOUS HIGH AVAILABLE MOISTURE WITHIN SUB-TROPICAL MOISTURE PLUME...FEEL ALL MODEL GUIDANCE MAY VERY WELL BE UNDER-FORECASTING QPF IN THE COLD SECTOR. SIGNIFICANT QPF OF A HALF INCH OR MORE IS POSSIBLE IN AREAS WHICH WILL BE AT OR BELOW FREEZING AT THE SURFACE...WITH HEAVIER AMOUNTS IN THE FAR SOUTHERN PART OF THE CWA WHERE DEEPER MOISTURE AND WARMER TEMPS ARE FORECAST.

NEXT QUESTION IS PTYPE. AGAIN...FAVORED THE NAM THERMAL PROFILES IN FAVOR OF A STRONGER AND FARTHER NORTH TRACK...WHICH WOULD IMPLY WARMER TEMPS ALOFT. NAM POINT SOUNDINGS FAVORABLE FOR FZRA AND IP ACROSS MUCH OF THE NORTHERN 2/3 OF THE CWA...WITH TENDENCY TOWARDS MORE SLEET FARTHER NORTH WITH A DEEPER NEAR SURFACE COLD LAYER. THE ONLY PORTION OF THE CWA WITH SOUNDINGS SUPPORT SNOW SUN NGT BASED ON CURRENT 12Z NAM RUN WOULD BE THE FAR NW CORNER FROM NEAR MCY TO BEH. FOLLOWING THIS TREND...HAVE REDUCED THE AMOUNT OF SNOW MENTION IN GRIDS AND INCREASED FZRA/IP MENTION. LEFT THE SOUTHERN 1/3 OF THE CWA AS MAINLY RAIN SUN NGT...POSSIBLY SOME FZRA LATE AS TEMPS COOL TO NEAR FREEZING. HAVE HOISTED A WINTER STORM WATCH FOR SUN NGT THROUGH MIDDAY MON FOR ROUGHLY THE NORTHERN 2/3 OF THE CWA FOR A COMBINATION OF FZRA AND SLEET...WITH SOME SNOW IN THE MIX AS WELL IN THE FAR NW. A FLOOD WATCH HAS ALSO BEEN HOISTED FOR THE SAME TIME FRAME ACROSS THE SOUTH FOR A COMBINATION OF POTENTIAL RIVER FLOODING AND ALSO POOR DRAINAGE TYPE FLOODING. STILL SOME UNCERTAINTY WITH EXACT TRACK AND SURFACE TEMPS...BUT IF THE EXPECTED GREATER QPF VERIFIES COULD SEE SIGNIFICANT ICE AND/OR SLEET ACCUMULATION FOR A PORTION OF THE CWA.

ON MONDAY SLOWER/WARMER NAM STILL FAVORS A MIXED BAG IN THE MORNING...THEN AS LOW/MID LEVEL CAA RAMPS UP IN THE AFTERNOON ANY REMAINING PRECIP SHOULD CHANGE TO ALL SNOW FROM NW TO SE. ATTENTION THEN TURNS TO LAKE EFFECT POTENTIAL. FROM LATE MON AFTERNOON THROUGH TUE NW FLOW OF MUCH COLDER AIR ARRIVES. 12Z NAM BUFKIT ANALYSIS SHOWING MODERATE COLLIER INDEX AND FAIRLY WELL ALIGNED NW FLOW WITH A GOOD AMOUNT OF AMBIENT SYNOPTIC SCALE MOISTURE BENEATH AN INVERSION CENTERED AROUND 7K FEET. INSTABILITY PARAMETERS AND PATTERN RECOGNITION POINT TOWARDS A POTENTIALLY DECENT LAKE EFFECT EVENT. THIS IS STILL SEVERAL DAYS OFF...AND WITH FOCUS ON SYNOPTIC EVENT STILL PLENTY OF TIME TO WATCH FUTURE MODEL TRENDS. FOR NOW HAVE INCREASED POPS TO LIKELY SE OF THE LAKE WITH A LARGE AREA OF CHANCE POPS IN AREAS FAVORED BY NW FLOW. LITTLE CHANGE TO REMAINDER OF FORECAST FROM TUE NGT THROUGH SAT.

&&

.IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR INZ020-INZ022-INZ023-INZ024-INZ025-INZ026-INZ027-INZ032- INZ033-INZ034.

FREEZING RAIN ADVISORY UNTIL 7 PM EST /6 PM CST FOR INZ008-INZ009-INZ013-INZ015-INZ016-INZ017-INZ018.

WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR INZ003-INZ004-INZ005-INZ006-INZ007-INZ008-INZ009-INZ012- INZ013-INZ014-INZ015-INZ016-INZ017-INZ018.

WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ FOR INZ003-INZ004-INZ005-INZ006-INZ007-INZ012-INZ014.

MI...WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

WINTER WEATHER ADVISORY UNTIL 7 PM EST FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

OH...FLOOD WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR OHZ016-OHZ024-OHZ025.

FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST SUNDAY FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

LM...NONE. &&

$$

SHORT TERM...HICKMAN LONG TERM....HITCHCOCK AVIATION...SKIPPER UPDATE...TAYLOR


AREA FORECAST DISCUSSION...UPDATED WWA SECTION
NWS TOPEKA KS
AFDTOP 1045 PM CST SAT JAN 13 2007

.DISCUSSION... WENT AHEAD AND REPLACED THE WATCH WITH ADVISORIES. WITH THE POSSIBILITY FOR A MIX OF SLEET AND SNOW...WENT WITH A WINTER WEATHER ADVISORY RUFFLY FROM EMPORIA TO HIAWATHA. SNOW IS EXPECTED TO BE THE PRIMARY PRECIP TYPE ACROSS NORTH CENTRAL KS...SO HAVE ISSUED A SNOW ADVISORY FOR THESE AREAS. THE WINTER STORM WARNING REMAINS UNCHANGED FROM PREVIOUS SHIFTS.

&&

WOLTERS

.PREV DISCUSSION /907 PM CST SAT JAN 13 2007/... WILL UPDATE THE FORECAST SHORTLY FOR CURRENT CONDITIONS. FOR THE MOST PART...PRECIP HAS ENDED ACROSS MOST OF THE FORECAST AREA. THERE ARE SOME SMALL BANDS OF VERY LIGHT PRECIP SEEN ON RADAR. IT IS HARD TO TELL IF THE PRECIP FALLING IS LIGHT FREEZING DRIZZLE OR POSSIBLY SNOW NEEDLES...ITS THAT LIGHT. THE LATEST RUC FORECAST WAS SHOWING SOME VERY LIGHT ISENTROPIC LIFT WITHIN THE CLOUD. THINK THIS MAY BE THE REASON FOR THE LIGHT PRECIP. NEVERTHELESS DO NOT ANTICIPATE ANY ACCUMULATING PRECIP FOR THE REST OF THE NIGHT SINCE LARGE SCALE FORCING HAS LEFT THE AREA FOR THE TIME BEING.

MAIN QUESTION IS WHAT TO DO WITH THE WATCH. AM CONSIDERING REPLACING THE WATCH WITH AN ADVISORY OF SOME SORT. THE 00Z NAM IS COMING IN SHOWING A SIMILAR SOLUTION TO THE DAY TIME RUNS. AS THE BASE OF THE UPPER LEVEL TROUGH ROTATES THROUGH THE SOUTHER ROCKIES AND INTO THE WESTERN CENTRAL PLAINS...LARGE SCALE FORCING IS EXPECTED TO AFFECT THE AREA ONCE AGAIN. HOWEVER THE FORCING DOES NOT LOOK TERRIBLY IMPRESSIVE WITH THE UPPER WAVE SHEARING OUT AS IT MOVES INTO THE PLAINS. WILL WAIT TO REPLACE THE WATCH AND PEEK AT THE 00Z GFS TO SEE IF IT SHOWS SOMETHING DIFFERENT FROM THE EARLIER RUNS. IF THE NAM IS CORRECT...LOOKS LIKE MAINLY SNOW WILL FALL ACROSS AREAS NORTH AND WEST OF MHK WITH AROUND 2 INCHES POSSIBLE. ALONG THE TURNPIKE WILL BE A LITTLE MORE PROBLEMATIC GIVEN FORECAST SOUNDINGS STILL SHOWING A WARM NOSE AROUND 800MB THROUGH 21Z. WILL KEEP THE WINTER STORM WARNING AS IS FOR THE TIME BEING...GIVEN THE POSSIBILITY FOR DECENT SLEET ACCUMULATIONS ONCE AGAIN.

AVIATION WISE...EXPECT CURRENT CONDITIONS TO REMAIN RELATIVELY STABLE THROUGH THE OVERNIGHT PERIOD. OBVIOUSLY THE LIGHT PRECIP SEEN ON RADAR WILL CAUSE A PROBLEM FOR AIRCRAFT. THIS SHOULD BE SPOTTY THOUGH AND CONFINED TO AREAS BELOW 4000FT. SFC VIS WILL DROP TO AROUND 4SM IN THESE LIGHT BANDS WITH CEILINGS AROUND 800FT. OTHERWISE ANTICIPATE A SLIGHT IMPROVEMENT TO THE CEILINGS AROUND 1000FT AS VERY WEAK ISENTROPIC LIFT BREAKS DOWN.

&&

WOLTERS

.PREV DISCUSSION /340 PM CST SAT JAN 13 2007/... CURRENTLY...SLEET SHOWERS EXITING THE CWA TO THE EAST WITH SOME LIGHT SNOW FILLING IN BEHIND. CONDITIONS HAVE IMPROVED ENOUGH TO LIFT ADVISORY ALL AREAS...AND WILL LET IT GO WITH THE AFTERNOON PACKAGE.

ANTICIPATING A LULL IN THE WEATHER FOR TONIGHT AS TODAYS SYSTEM DEPARTS EAST AND UPPER TROF STILL LUMBERING INTO THE GREAT BASIN. BASE OF THE MAIN TROF PROGGED TO MAKE IT INTO NORTHERN NM BY MORNING...EJECTING SHORTWAVES INTO SOUTH CENTRAL KANSAS AT THAT TIME AS WELL. GFS STRONGER WITH THESE FEATURES...AND WHILE SEVERAL WAVES ARE SEEN OVER THE SW US IN THE WATER VAPOR...STILL DIFFICULT TO DISCERN WHICH WILL MAKE IT HERE AND WHEN. CONSENSUS SEEMS TO BE THAT BEST WINDOW FOR ACCUMULATING SNOWS IS NOW MAINLY IN THE 15Z-0Z TIMEFRAME. GUIDANCE NUMBERS FOR SNOW HAVE COME DOWN...AND NOT MUCH INSTABILITY IN THE COLUMN. BUT WITH SOME FRONTOGENESIS...POT VORT AND Q VECTOR CONVERGENCE STILL OCCURING OVER OUR AREA AT THIS TIME...WILL KEEP SOME ADVISORY ACCUMULATIONS IN THE FORECAST FOR MUCH OF THE CWA. FAR SE COUNTIES WHERE WARNING IS IN EFFECT HAVE ALREADY SEEN OVER AN INCH OF SLEET IN PLACES...AND WILL BE EXACERBATED BY SOME SNOW ACCUMULATION ON TOP OF THIS TOMORROW. WITH PWS AROUND HALF AN INCH AND SNOW RATIOS LIKELY OVER 10/1 IN THE COLD AIR...AM NOT READY TO DROP THE WATCH JUST YET...AND WILL TREND GRIDS TOWARDS ADVISORY NUMBERS.

MAIN UPPER LEVEL WAVE FINALLY EJECTS OUT THROUGH THE PLAINS AND EXITS TO THE NORTHEAST OF THE CWA BY 12Z MONDAY...BUT NOT BEFORE PRODUCING SOME LIGHT SNOW ACROSS THE CWA...MAINLY DURING THE EVENING ALONG AND NORTH OF I-70 AS DRIER AIR AND SUBSIDENCE INCREASE FROM THE SOUTHWEST. ADDITIONAL AMOUNTS GENERALLY SHOULD BE FROM LESS THAN HALF AN INCH SOUTH TO AN INCH TO AN INCH AND A HALF NORTHEAST CORNER OF THE CWA. ALTHOUGH LOWS SUNDAY NIGHT WILL BE COLDER...CLOUDS AND INCREASING WINDS WILL KEEP TEMPERATURES FROM FALLING AS MUCH AS THEY OTHERWISE WOULD...SO WILL KEEP GENERALLY IN THE 5 TO 12 DEGREE RANGE. THE STRATUS ON MONDAY WILL THEN LINGER IN THE MORNING BUT START TO BREAK UP BY AFTERNOON. STILL...WITH EXPECTED SNOW/ICE COVER...THIS WILL LIMIT HIGHS TO THE TEENS.

TUESDAY NIGHT SHOULD BE THE COLDEST NIGHT WITH DIMINISHING WINDS...DECREASING CLOUDS AND SNOW/ICE COVER. WILL GO WITH MOST TEMPS NEAR ZERO FOR NOW...BUT DEPENDING ON SNOW/ICE DEPTHS...COULD SEE TEMPS A FEW DEGREES COLDER. ALTHOUGH SUNSHINE SHOULD BE THE RULE ON TUESDAY...MIXING WILL BE WEAK FOLLOWING VERY COLD MORNING LOWS...SO THIS WILL LIMIT HIGHS TO UPPER TEENS TO LOWER 20S. RETURN FLOW ON THE BACK SIDE OF THE HIGH SHOULD THEN KEEP LOWS ABOVE ZERO INTO WEDNESDAY MORNING WITH MOST HIGHS IN THE MIDDLE TO UPPER 20S. WILL KEEP THE REST OF THE FCST DRY ON THROUGH EARLY NEXT WEEKEND AS THE GFS/ECMWF SEEMS TOO PROGRESSIVE AND TOO FAR EAST WITH CUTOFF LOW COMING OUT OF THE SOUTHWEST U.S. WEDNESDAY. ALSO LOW CONFIDENCE WITH THE ARRIVAL TIME OF THE NEXT SYSTEM BY SATURDAY.

EITHER WAY...WITH THE SNOW/ICE COVER WILL SEE A "GRADUAL" MODERATION IN TEMPS THROUGH THE REST OF THE WEEK INTO THE 30S THURSDAY AND FRIDAY AND SOME LOWER 40S SOUTHERN CWA BY NEXT WEEKEND.

&&

.TOP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING THROUGH 06Z MONDAY FOR COFFEY...FRANKLIN AND ANDERSON COUNTIES.

WINTER WEATHER ADVISORY FROM 16Z SUNDAY UNTIL 06Z MONDAY FOR LYON... MORRIS...WABAUNSEE...OSAGE...SHAWNEE...DOUGLAS...JEFFERSON...JACKSON AND BROWN COUNTIES.

SNOW ADVISORY FROM 16Z SUNDAY UNTIL 06Z MONDAY FOR ALL OTHER COUNTIES.

&&

$$


AREA FORECAST DISCUSSION...UPDATED
NWS LOUISVILLE KY
AFDLMK 910 PM EST MON JAN 15 2007

.UPDATE...

WITHIN COLD ADVECTION/POST FRONTAL LOW CLOUDS...AREAS OF LIGHT PRECIP ARE MOVING THROUGH THE LMK CWA AS OF 2Z. BASED ON RECENT ACARS SOUNDINGS AT SDF...AND MOST RECENT RUC MODEL...PRECIP TYPE SHOULD BE LIQUID. ADDITIONAL LIGHT PRECIP OBSERVED UPSTREAM OVER IL/IN...HEADING IN THIS GENERAL DIRECTION. OVERNIGHT...PTYPE WILL BE TRICKY. AS IS THE SITUATION RIGHT NOW...FCST SOUNDINGS FROM NAM/GFS/RUC SHOW ATMOSPHERE ABOVE -5C OR SO REMAINING FAIRLY DRY OVERNIGHT...LEADING TO MORE OF A DRIZZLE ENVIRONMENT. THIS IS EVEN AS THE NEAR SURFACE LEVELS COOL TO NEAR OR BELOW FREEZING.

WILL UPDATE FCST TO ADD MENTION OF PATCHY -FZDZ LATE TONIGHT AND EARLY TUESDAY MORNING OVER THE N 1/2 OF THE LMK CWA...ALSO MENTIONING SLIGHT CHANCES FOR -SHRA/-SHSN FOR ANY ISOLATED ELEMENTS WHICH CAN SATURATE UP INTO THE -10C TO -20C LEVELS OVERNIGHT. ROADWAY TEMPS RIGHT NOW ARE RELATIVELY WARM...UPPER 30S TO LOWER 40S...BUT EXPECT THOSE TO COOL OVERNIGHT ESPECIALLY IN SRN IND AND ADJACENT PARTS OF KY. EVEN JUST A LITTLE -FZDZ CAN HAVE A BIG IMPACT.

INTO TUESDAY...MODELS ARE INDICATING THAT A PLUME OF ENHANCED MOISTURE ORIGINATING FROM LAKE MICH MAY CONTRIBUTE TO SOME SCT SHSN INTO PARTS OF THE BLUEGRASS AND NE KY. ONGOING FCST HAS THIS WELL IN HAND...BUT HAVE UPPED POPS INTO 40% RANGE FOR OUR FAR NE MOST COUNTIES BASED ON MOST RECENT DATA. SOME LOCALIZED MINOR ACCUMS POSSIBLE THERE SHOULD THESE SHOWERS MATERIALIZE.

NO SIGNIFICANT CHANGES TO TEMPS/WINDS/DEWPOINTS/CLOUDS TONIGHT AND TUESDAY.

UPDATED FCST EXPECTED OUT BY 945 PM EST.

CS

&&

.PREV DISCUSSION... /ISSUED 328 PM EST MON JAN 15 2007/

SHORT TERM (TONIGHT AND TUESDAY)..

FRONTAL BOUNDARY THAT HAS BEEN RESPONSIBLE FOR THE RAINY WEATHER OF LATE CONTINUES TO MOVE EAST THROUGH THE COMMONWEALTH. LARGE POST FRONTAL BAND OF PRECIPITATION CONTINUES TO AFFECT THE SOUTHEASTERN HALF OF THE FA. PRECIPITATION CONTINUES TO MOVE STEADILY EASTWARD AND SHOULD EXIT THE LMK FORECAST AREA BETWEEN 400 AND 500 PM EST. TEMPERATURES CONTINUE TO FALL IN THE WAKE OF THE FRONT. SIGNIFICANTLY COOLER AIR STILL RESIDES WELL WEST OF THE FA. TEMPERATURES ARE FALLING INTO THE UPPER 30S NOW ACROSS THE NORTHWEST CWA AND THIS TREND SHOULD CONTINUE. THE RUC SFC TEMP FCST HAS BEEN DOING A BANG UP JOB WITH THIS AND WILL FOLLOW ITS FORECAST CLOSELY FOR TEMPERATURES THIS AFTERNOON AND EVENING. WITH THE THREAT OF EXCESSIVE RAIN COMING TO AN END...THE FLOOD WATCH WILL BE ALLOWED TO EXPIRE AT 400 PM EST/300 PM CST.

FOR TONIGHT...SHORT TERM MODELS CONTINUE TO BE IN GOOD AGREEMENT THROUGH THE FIRST 24 HOURS OF THE FCST PD. POST FRONTAL PRECIP IS FCST TO BE WELL EAST OF THE FA BY 00Z TONIGHT. LATEST RUC AND WRF SOUNDINGS SUPPORT STEEPENING LOW-LEVEL LAPSE RATES THROUGH THE EVENING THAT WOULD PROMOTE AREAS OF DRIZZLE INITIALLY THROUGH ABOUT 03Z. AFTER THAT...SUFFICIENT TOP-DOWN COOLING WOULD RESULT IN A TRANSITION OVER TO SNOW FLURRIES FROM WEST TO EAST. UPSTREAM RADARS SHOWING SOME LIGHT SNOWS ACROSS NORTHERN MISSOURI AND NW ILLINOIS DROPPING EAST-SOUTHEAST. MODELS GENERALLY WEAKEN THIS AREA AND SHIFT IT NORTH OF THE OHIO RIVER. HOWEVER...WILL NEED TO WATCH THIS CLOSELY AS THE EVENING PROGRESSES. SFC TEMPERATURES WILL CONTINUE TO SLOWLY FALL THROUGH THE EVENING...WITH TEMPERATURES DROPPING TO NEAR FREEZING AROUND BETWEEN 06-08Z. OVERNIGHT MINIMUMS LOOKS TO COOL INTO THE MID AND UPPER 20S.

TUESDAY...AS FRONTAL BOUNDARY CONTINUES EAST...HIGH PRESSURE IS FORECAST TO BUILD IN ACROSS THE MIDWEST. RESULTANT LOW-LEVEL FLOW WITH BE FROM THE NORTH/NORTH-NORTHWEST. WITH THE LAKES FAIRLY WARM DUE TO RECENT MILD WEATHER...LAKE EFFECT SNOW MACHINE IS FORECAST TO CRANK UP. BOTH WRF AND GFS SOLUTIONS SHOW BEST LAPSE RATES FOR SNOW SHOWERS ACROSS THE NE THIRD OF OUR FA (BLUEGRASS REGION). THUS WILL CONTINUE CHANCE OF SNOW SHOWERS ACROSS THAT AREA. STRONG COLD ADVECTION IS FCST TO CONTINUE AND AFTERNOON TEMPS WILL NOT RISE MUCH DURING THE AFTERNOON. HIGHS IN THE UPPER 20S TO THE VERY LOW 30S LOOK LIKELY. GENERALLY TRENDED TEMPS CLOSER TO RAW 2M SFC TEMPS FROM OUR LOCAL HI-REZ WRF AND GFS SOLUTIONS.

-MJ

LONG TERM (TUESDAY NIGHT THROUGH MONDAY)...

TUESDAY NIGHT AND WEDNESDAY...

WE WILL FINALLY SEE A GENERAL CLEARING TAKE PLACE ON LATE ON TUESDAY AND TUESDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION AND THEN SHIFTS OFF TO THE EAST ON WEDNESDAY. A RETURN TO MUCH COLDER BUT MORE NORMAL TEMPS.

WEDNESDAY THROUGH SATURDAY NIGHT...

WE WILL PRIMARILY BE UNDER A NORTHWESTERLY FLOW REGIME AT 500 MB AS THE WESTERN RIDGE...INITIALLY FLATTENED BY A SHORT WAVE ON TUESDAY THEN REBUILDS INTO SOUTHWESTERN CANADA...THE ABOVE MENTIONED SHORT WAVE WILL DROP ESE THROUGH THE CENTRAL U.S. AND BRING ANOTHER SURGE OF SEASONABLY COLD ARCTIC AIR INTO THE REGION AS A SURFACE RIDGE BUILDS SOUTHEAST INTO THE WESTERN PLAINS. A SERIES OF WEAKER SYSTEMS DRIFTING BY TO OUR NORTH AND EAST SHOULD HELP TO REINFORCE AND KEEP THE COLD AND DRY AIR IN PLACE THROUGH THE REST OF THIS PERIOD. THIS COULD LEAD TO SOME MIXED WINTERY PRECIPITATION LATER.

SUNDAY AND MONDAY...

THE GENERAL CONSENSUS IS THAT A CLOSED LOW WILL SETUP OFF THE SOUTHERN CALIFORNIA COAST LATE THIS WEEK. OVER THE WEEKEND THIS SYSTEM OPEN AND TREK ENE INTO THE CENTRAL U.S. BY LATE ON SUNDAY INTO MONDAY. INITIAL INDICATIONS ARE THAT THE ATMOSPHERE WILL BE COLD ENOUGH FOR A POSSIBLE SNOW TO RAIN SCENARIO ON SUNDAY NIGHT THAT DOES CHANGE OVER TO ALL RAIN ON MONDAY AS A SURFACE LOW MOVES INTO THE CENTRAL U.S. FROM THE SOUTHERN PLAINS. --21

&&

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

$$


AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 430 PM EST SUN JAN 14 2007

.SYNOPSIS AND SHORT TERM...

WATER VAPOR LOOP AND RUC/LAPS ANALYSIS SHOW SOUTHWEST FLOW ALOFT BUT COLDER AIR REMAINS ENTRENCHED OVR PLAINS INTO UPR LAKES. FRONTAL BOUNDARY HAS SLIPPED SOUTH OF UPR MI ATTM. WINDS BECOMING NORTHERLY IN WAKE OF TROUGH. DESPITE LOW INVERSION AROUND 3 KFT PER MIDDAY TAMDAR DATA AT CYQT AND KSAW...LK EFFECT HAS BEEN PROFICIENT WITH SOME ACCUMS REPORTED BY SPOTTER IN MOHAWK IN HOUGHTON COUNTY. LATEST RADAR AND VIS SAT EVEN SHOW ENHANCED CONVERGENCE BAND BTWN MQT AND STDM4 OVR SCNTRL LK SUPERIOR. TO THE SW OF UPR LAKES LARGE AREA OF MOSTLY SNOW IS LIFTING NE ACROSS NEB AND WESTERN IA. THIS SNOW IS ASSOCIATED WITH MID LEVEL LOW IN CNTRL KS AND IT NOW LOOKS LIKE THIS SNOW WILL MAKE IT INTO UPR MI LATE TONIGHT INTO MONDAY. SNOW AMOUNTS AND HEADLINES ARE MAIN CONCERNS IN SHORT TERM.

NORTHERLY FLOW TONIGHT WITH TEMPS AT TOP OF INVERSION AROUND -17C WILL KEEP LK EFFECT GOING THROUGH EVENING. NOTED CONVERGENCE BAND MAY ENHANCE SNOWFALL BRIEFLY THIS EVENING OVR NCNTRL. OTHERWISE... EXPECT SNOW TO INCREASE AFTER MIDNIGHT AS SYNOPTIC SNOW ARRIVES FM THE SOUTH. HOW FAR NORTH WILL SHIELD OF DEEPER MOISTURE/UPR LEVEL FORCING AND SYNOPTIC SNOW SURGE WAS MAIN QUESTION OF THE SHIFT. UNLIKE YDY FOR THE MOST PART GFS/NAM/UKMET/ECMWF/CANADIAN GEM ARE ALL ON SAME PAGE. BLEND OF QPF OUTPUT GIVES MOST AREAS A SOLID 0.20 TO 0.25 INCHES OF LIQUID 00Z MON THROUGH 00Z TUE. USING BUFKIT COBB SNOW-WATER RATIOS AND UWM ROEBBER SNOW RATIO FORECAST PAGE GIVES HIGHER RATIO THAN TYPICAL SYNOPTIC EVENT...MORE IN LINE WITH 15-20 TO 1. IN GENERAL...THIS GIVES TOTAL AMOUNTS OF 3 TO 5 INCHES OVR SOUTHERN TIER...WHICH JUSTIFIES AN ADVY THROUGH LATE TOMORROW. COORD THIS WITH DLH AND GRB.

BASED ON AIRMASS OVERHEAD AND WAY LK EFFECT HAS TURNED OUT LAST FEW DAYS...EXPECT EVEN HIGHER RATIOS OVR PRONE LK EFFECT AREAS. LOWER LEVEL WINDS THROUGH H85 ON AVERAGE FM 360 DIRECTION...ALTHOUGH NAM/CANADIAN GEM ARE A BIT MORE TOWARD 030. INVERSION HEIGHTS ARE FAIRLY LOW...5-7KFT...BUT WITH DEEP MOISTURE PRESENT...AND TEMPS AT TOP OF INVERSION TOWARD -18C...SIGNIFICANT LAKE CONTRIBUTION IS EXPECTED. UPGRADED TO LK EFFECT SNOW WARNING FOR FAR WEST AND NCNTRL UPR MI. SOME LOCALIZED AREAS MAY SEE AROUND A FOOT OF SNOW FM THE EVENT. ALTHOUGH WINDS ARE NOT AS FAVORABLE FOR OTHER ZONES NEAR LK SUPERIOR...SYNOPTIC MOISTURE AND SOME LAKE CONTRIBUTION TIPS SCALES TOWARD ADVY FOR ALL BUT LUCE COUNTY AS NORTHEAST WINDS DO NOT PRODUCE PROVIDE SUITABLE FETCH FOR LK INDUCED CONVECTION. ONE NOTE ABOUT THE KEWEENAW. AIRMASS LURKING OVER NORTHERN LAKE SUPERIOR IS QUITE DRY AND SOUNDINGS EVEN FM THE HIGHER RESOLUTION MODELS INDICATE SHARP CUTOFF TO DEEPER MOISTURE. THIS MAY IMPACT INTENSITY OF INDIVIDUAL SNOW BANDS. STILL...SINCE LAKE IS SHOWING NO ICE ON IT AND WATER TEMPS ARE RUNNING +3C TO +4C AND THERE IS SOME SYNOPTIC SUPPORT...BELIEVE THE HIGHER TERRAIN OF NORTHERN KEWEENAW AND TOWARD ONTONAGON COUNTY COULD EEK INTO ADVY CRITERIA. ALL LK SUPERIOR HEADLINES EXPIRE LATE MON EVENING.

.LONG TERM...(MON NIGHT THROUGH SUNDAY)

MON NIGHT...AS THE SYNOPTIC SCALE SUPPORT WITH THE QVECTOR CONV WITH THE MID LVL TROF AND DEEPER MOISTURE DEPARTS THE SNOW OVER SOUTH UPPER MICHIGAN WILL TAPER OFF QUICKLY EARLY IN THE EVENING...AND THE LES INTENSITY NORTH WILL DIMINISH SIGNIFICANTLY. HOWEVER...THE NAM AND GFS CONTINUE TO INDICATE DECENT LOW LEVEL CONV INTO N CNTRL UPPER MI (VCNTY MARQEUTTE) AND OVER THE WEST(NEAR KIWD) THROUGH 06Z. TEMPS OF -18C NEAR THE TOP OF THE 4K FT INVERSION SHOULD STILL FAVOR BANDS OF LIGHT TO MODERATE LES. AS THE WINDS BACK TO NW OVERNIGHT THE LES FOCUS WILL SHIFT INTO AREAS FROM KP53 EASTWARD. THE SHORTER FETCH INTO W UPR MI AND EVEN LOWER INVERSION HEIGHTS SHOULD ALLOW LES TO TAPER OFF TO JUST LIGHT SNOW OR FLURRIES WITH ONLY MINOR AMOUNTS AFT 06Z.

TUE...ALTHOUGH THE SFC RDG WILL BUILD INTO THE AREA...LAKE INDUCED TROUGHING WILL KEEP NW OR NW WINDS GOING WITH BEST LOW LVL CONV EAST OF MARQEUTTE. BY AFTERNOON...THE COMBINATION BACKING WINDS AND ADDITIONAL LOW LEVEL DRYING...WAA AND BACKING WINDS SHOULD BRING AN END TO ANY SIGNIFICANT LES. THE EXCEPTION WILL BE OVER THE FAR E CWA WHERE LONGER FETCH AND CLOSER PROXIMITY TO THE DEPARTING 850 MB THERMAL TROF WILL KEEP LIGHT LES GOING.

WED INTO THU...GLBL MDLS ARE CONSISTENT WITH PATTERN WITH STRONG WAA DEVELOPING AS THE SFC RDG SINKS SE AND A PLAINS SHRTWV AND SFC TROF MOVE TOWARD THE AREA. AS A RESULT...TEMPS SHOULD REBOUND TO READINGS AOA NORMAL WED. MODERATE QVECTOR CONV WITH THE PROMINENT 500 MB TROF WARRANT AT LEAST CHANCE POPS ACROSS THE CWA WITH LES CHANCES INCREASING BY LATE THU AS CAA TAKES OVER BEHIND THE SFC FRONT/TROF AS 850 MB TEMPS FALL TO NEAR -15C.

FRI THROUGH SUN...GOOD LES CHANCES CONTINUE IN GENERAL FOR NW FLOW FAVORED LOCATIONS. NW NORTHERN STREAM FLOW WILL BRING A FEW CLIPPER SHRTWVS THROUGH THE AREA BUT LESS CERTAINTY WITH TIMING/STRENGTH OF THESE FEATURES AND IMPACT ON WIND DIRECTION.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY FROM 11 PM THIS EVENING TO 11 PM EST MONDAY FOR MIZ001>004-006-084-085.

LAKE EFFECT SNOW WARNING FROM 11 PM EST /10 PM CST/ THIS EVENING TO 11 PM EST /10 PM CST/ MONDAY FOR MIZ005-009.

SNOW ADVISORY FROM 1 AM TO 11 PM EST MONDAY FOR MIZ013.

SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST MONDAY FOR MIZ010>012.

&&

$$

JLA(SHORT TERM) JLB(LONG TERM)


AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 835 AM PST SUN JAN 14 2007

.SYNOPSIS...A COLD AND DRY AIR MASS WILL REMAIN OVER WESTERN WASHINGTON THROUGH MONDAY NIGHT. A PACIFIC FRONTAL SYSTEM WILL PASS THROUGH THE AREA TUESDAY. DRY WEATHER WILL RETURN TO THE AREA WEDNESDAY AND THURSDAY. ANOTHER WEATHER SYSTEM WILL BRING ANOTHER CHANCE OF PRECIPITATION TO THE AREA TOWARD THE END OF THE WEEK.

&&

.SHORT TERM...COLD AIR HAS A GRIP OVER THE STATE AND WESTERN WASHINGTON TEMPERATURES RANGE FROM THE MID TEENS TO THE 20S THIS MORNING. MOISTURE OFF THE SOUND AND UNFROZEN LAKES ARE RESULTING IN AREAS OF FREEZING FOG MAKING SOME ROADS SLICK AND LOCALLY REDUCING VISIBILITIES TO A MILE OR SO. THE FOG IS SHALLOW AND SHOULD BURN OFF MIDDAY. REALLY LIGHT OFFSHORE PRES GRADIENTS COMBINED WITH A ISOTHERMAL LAPSE RATE AT SEATTLE FROM THE SURFACE TO 10000 FT PER ACARS SOUNDINGS...SOME SNOW ON THE GROUND...AND LOW MID JAN SUN ANGLES ALL POINT TO TEMPERATURES TODAY STRUGGLING TO GET ABOVE FREEZING. CI MOVING AROUND THE RIDGE AT 132W WILL OCCASIONALLY SPILL INTO THE AREA FILTERING THE AFTN SUNSHINE.

TONIGHT WILL BE QUITE COLD AGAIN...THOUGH SOME HIGH CLOUDINESS MAY KEEP TEMPERATURES ABOUT 2 DEG HIGHER THAN THIS MORNING MOST AREAS.

TEMPERATURES WILL CONTINUE TO MODERATE ON MON BY A COUPLE DEGREES THOUGH SUNSHINE WILL BE FILTERED BY A THICKENING LAYER OF HIGH CLOUDS. AIR MOVEMENT WILL CONTINUE TO BE MINIMIZED BY LIGHT GRADIENTS AND INCREASING TEMPERATURE INVERSIONS TONIGHT AND MON.

STAGNATION WILL CONTINUE TO BE AN ISSUE THRU MON NIGHT WITH THE VERY STABLE AIR MASS IN PLACE AND LIGHT PRES GRADIENTS. WILL MAINTAIN THE AIR STAGNATION ADVISORY THRU MON NIGHT OR TUE MORNING.

THE NEXT PROBLEM IN THE FORECAST WILL BE LATE MON NIGHT AND TUE. BOTH THE NAM AND THE GFS SHOW A SPLITTING FRONT MOVING INTO THE AREA TUE MORNING. WHILE TEMPERATURES ARE VERY SLIGHTLY ABOVE FREEZING IN THE LAYER FROM 1000 FT TO 3000 FT...THE AIR MASS WILL BE QUITE DRY AND PRES GRADIENTS WITH THE INCOMING FRONT WILL BE WEAKLY OFFSHORE. MODEL QPF WITH THE INCOMING FRONT IS ON THE ORDER OF 0.15-0.40 INCHES ACROSS THE AREA TUE...AND LOW LEVEL THICKNESS ARE AROUND 1295 M. A QUICK LOOK AT NAM BUFR SOUNDING FORECASTS AS WELL AS FORECAST SOUNDINGS OFF THE INCOMING GFS ALL POINT TO MOST AREAS IN THE INTERIOR SEEING SNOW TUE MORNING WITH POSSIBLE ACCUMULATIONS IN THE 2-4 INCH RANGE. PCPN MAY CHANGE TO RAIN SHOWERS WITH THE PASSAGE OF THE FRONT DURING THE DAY SEATTLE SOUTHWARD...BUT SNOW LEVELS REMAIN QUITE LOW...AND ANY POST FRONTAL CONVERGENCE LATE IN THE DAY INTO EARLY WED MORNING COULD STILL CAUSE FROZEN PCPN ON HILLS N/E OF SEATTLE. WILL CONTINUE TO EVALUATE THIS BEFORE THE AFTERNOON PACKAGE GOES OUT. ALBRECHT.

.LONG TERM...LONG TERM MODELS NOT SHOWING A LOT OF RUN TO RUN CONSISTENCY BUT THE GENERAL TREND IS FOR MORE SHORT WAVE RIDGING FOR WEDNESDAY AND THURSDAY THEN ANOTHER SYSTEM MOVING INTO THE AREA FRIDAY INTO SATURDAY. 00Z RUNS A LITTLE FASTER AND GIVEN THE EXTENDED MODELS HAVE GIVEN THE RIDGES A LITTLE TOO MUCH STRENGTH IN THE LAST FEW RUNS WILL GO AHEAD AND MOVE UP THE CHANCE POPS TIMING INTO THE FIRST HALF OF FRIDAY. CONFIDENCE NOT HIGH IN THE EXTENDED AT THIS POINT. FELTON

&&

.AVIATION...INCREASING HIGH CLOUDS DURING THE DAY...OTHERWISE EXPECT AREAS OF 1/4-1/2SM FZFG CIGS BKN001-003 TO MOSTLY DISSIPATE BY 20Z. CONTINUED WEAK LOW LEVEL OFFSHORE FLOW.

KSEA...FOG IS EXPECTED TO REMAIN OUTSIDE THE AIRPORT COMPLEX. MEANWHILE...WINDS WILL BE LIGHT AND VARIABLE WITH MAINLY HIGH CLOUDS ANTICIPATED.

&& .SEW WATCHES/WARNINGS/ADVISORIES...AIR STAGNATION ADVISORY INTERIOR LOWLANDS THROUGH TUESDAY MORNING.

$$

WEATHER.GOV/SEATTLE.


AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 300 AM EDT FRI JAN 12 2007

.SHORT TERM (TDA AND TONIGHT)...

MID JAN WEATHER FINALLY...THO WE`RE NOT COMPLAINING. EXPECT WIDESPREAD FLURRIES/SCT TO NUMEROUS SNOW SHOWERS...TEMPS AROUND FREEZING TDA. READINGS DROPPING INTO THE TEENS TNGT.

UPR LEVEL TROF TO APPROACH OUR FA TDA AND MOVE THRU EARLY TNGT...WITH A SHRTWV RIDGE QUICKLY IN ARREARS. LO CLOUDS/FLURRIES OBSERVED ATTM UPSTREAM FROM MO INTO IL AND IN. CURRENT ACARS SOUNDING INDICATING MOISTURE UP TO ABOUT 850 MBS AT A TEMP OF ABOUT -11C. FCST SOUNDINGS SHOW MOISTURE DEEPENING A BIT UP TO ABOUT 800 MBS TDA AT TEMPS AROUND -15C AS LO LEVEL WINDS VEER TO NNW...RESULTING IN A FETCH OFF LAKE MI PRIMARILY AFFECTING OUR E/NE SECTIONS OF THE FCST AREA. MODELS SHOW SIMILAR LO LVL MSTR PROGS TDA WITH THE GFS INDICATING .01 TO .05 WATER EAST. THINKING SNOW SHOWERS WILL BE NUMEROUS PRIMARILY IN THE BLUEGRASS TDA...WITH SCT SNOW SHOWERS WEST OF THERE AND JUST FLURRIES SCNTRL KY. DAYLIGHT/RELATIVELY WARM GROUND TEMPS SHUD INHIBIT ACCUMS...WILL USE LITTLE OR NO ACCUM TERMINOLOGY EAST WITH LIKELY POPS.

WE SHUD START OFF AROUND THE 30 DEGREE MARK AT SUNRISE MOST PLACES AND WITH COLD ADVECTION...HOLD NEARLY STEADY WITH 850 MB THERMAL TROF ACRS OUR FA THIS AFTN.

CLOUDS WILL DECREASE TNGT WITH TROF PASSAGE...THO SNOW SHOWERS/FLURRIES MAY CONT EAST EARLY THIS EVE...WILL END HOWEVER AT OOZ TO BE CONSISTENT WITH PREVIOUS FCST. TEMPS TO FALL INTO THE TEENS MOST AREAS.

DK

LONG-TERM (WEDNESDAY THROUGH MONDAY)...

FOR THE MAJORITY OF THIS WEEK...TEMPS WILL GENERALLY RUN AT OR JUST BELOW NORMALS FOR THIS TIME OF YEAR. THIS IS RELATIVELY MUCH COLDER THAN THE TEMPS WE HAVE EXPERIENCED THUS FAR THIS YEAR...AS WE ARE RUNNING 12-13 DEGREES ABOVE NORMAL FOR JANUARY!

WEDNESDAY-THURSDAY...

SFC HIGH PRESSURE AND MAINLY ZONAL FLOW ALOFT WILL DOMINATE WED AND THRS ACROSS THE REGION. WITH LIGHT WINDS AND DRY CONDITIONS...WED AND WED NIGHT WILL BE COLD WITH HIGHS IN THE 30S TO NEAR 40 DOWN SOUTH...AND LOWS IN THE LOW 20S. WILL BE A BIT WARMER ON THRS AS HIGH PRESSURE SLIDES EAST AND SOUTHERLY FLOW COMMENCES.

FRIDAY-MONDAY...

AT THE BEGINNING OF THIS PERIOD...A CLOSED LOW WILL BE LOCATED OVER THE SWRN CONUS. BEFORE THIS MOVES EASTWARD...STRONG NORTHWEST FLOW ACROSS THE NRN U.S. WILL BRING A REINFORCING SHOT OF COLD ARCTIC AIR INTO THE REGION LATE FRIDAY AND INTO SATURDAY. HOWEVER...IF THE CLOSED LOW BECOMES MORE OF AN OPEN WAVE AND MOVES MORE QUICKLY EASTWARD...THIS ARCTIC AIR WOULD BE MORE TO OUR N/NE. CURRENT GRID TEMPS REFLECT A MINOR REINFORCEMENT WHICH LOOKS GOOD SO NO ADJUSTMENTS NEEDED.

ON FRIDAY...THE UPPER JET IS FAIRLY ZONAL AND STRONG...AROUND 160-180KTS. BECAUSE OF THE FAST ZONAL FLOW ALOFT...THINK THE CLOSED LOW OVER SWRN CONUS WILL QUICKLY EJECT OUT INTO THE PLAINS. MOST RECENT MRF MODEL RUNS OPEN UP THIS LOW OVER THE CENTRAL PLAINS BY SUNDAY MORNING. BUT THE TREND FROM THE PAST FOUR (THREE/TWO) RUNS OF THE GFS (GFS ENSEMBLES/ECMWF) HAVE REALLY SPED THIS UP. FOR INSTANCE...THE 06Z GFS RUN FROM YESTERDAY HAD THE UPPER LOW WELL OFF THE SE CALI COAST FRIDAY MORNING. THE 00Z RUN HAS THE OPENING LOW OVER ARIZONA. THE RESULT IS THAT THE SOUTHERN STREAM IS SHOWING QPF GETTING CONTINUALLY CLOSER TO OUR SRN CWA. IF THE MODELS CONTINUE THIS PROGRESSIVE TREND...THEN MAY HAVE TO INSERT PRECIP INTO THE FORECAST SOONER. IN FACT...THE GFS ENSEMBLES SHOW A BIT OF QPF ACROSS OUR SRN CWA ON FRIDAY WITH THE FIRST PUSH OF MOISTURE TOWARD THE REGION. WILL HAVE TO WATCH LATER RUNS TO SEE IF THIS HOLDS. FOR NOW WILL JUST BEEF UP CLOUDS DOWN SOUTH.

SECOND (MAIN) WAVE OF MOISTURE FROM THE SOUTHERN STREAM LOOKS TO OCCUR DURING THE SUNDAY-MONDAY TIMEFRAME WHEN THE UPPER LOW EJECTS OUT INTO THE MIDWEST. AGAIN...IF MODEL TREND CONTINUES...THIS WOULD OCCUR SOONER. RIGHT NOW WE HAVE POPS IN THE GRIDS SUNDAY NIGHT...BUT MAY NEED A SOONER ONSET IF MORE PROGRESSIVE MODEL TREND CONTINUES.

FOR NOW...MADE NO POP CHANGES...BUT ADJUSTED TEMPS DOWN ON WEDNESDAY...CLOSER TO THE OFTEN-TIMES UNJUSTLY IGNORED FWC GUIDANCE.

AL

&&

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

$$


AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 1030 AM EDT FRI JAN 12 2007

.MORNING UPDATE:... ONLY MINOR TWEAKS NEEDED TO TEMP TRENDS FOR TODAY...REMAINDER OF FCST STILL LOOKS GOOD. --21

.SHORT TERM (TDA AND TONIGHT)...

MID JAN WEATHER FINALLY...THO WE`RE NOT COMPLAINING. EXPECT WIDESPREAD FLURRIES/SCT TO NUMEROUS SNOW SHOWERS...TEMPS AROUND FREEZING TDA. READINGS DROPPING INTO THE TEENS TNGT.

UPR LEVEL TROF TO APPROACH OUR FA TDA AND MOVE THRU EARLY TNGT...WITH A SHRTWV RIDGE QUICKLY IN ARREARS. LO CLOUDS/FLURRIES OBSERVED ATTM UPSTREAM FROM MO INTO IL AND IN. CURRENT ACARS SOUNDING INDICATING MOISTURE UP TO ABOUT 850 MBS AT A TEMP OF ABOUT -11C. FCST SOUNDINGS SHOW MOISTURE DEEPENING A BIT UP TO ABOUT 800 MBS TDA AT TEMPS AROUND -15C AS LO LEVEL WINDS VEER TO NNW...RESULTING IN A FETCH OFF LAKE MI PRIMARILY AFFECTING OUR E/NE SECTIONS OF THE FCST AREA. MODELS SHOW SIMILAR LO LVL MSTR PROGS TDA WITH THE GFS INDICATING .01 TO .05 WATER EAST. THINKING SNOW SHOWERS WILL BE NUMEROUS PRIMARILY IN THE BLUEGRASS TDA...WITH SCT SNOW SHOWERS WEST OF THERE AND JUST FLURRIES SCNTRL KY. DAYLIGHT/RELATIVELY WARM GROUND TEMPS SHUD INHIBIT ACCUMS...WILL USE LITTLE OR NO ACCUM TERMINOLOGY EAST WITH LIKELY POPS.

WE SHUD START OFF AROUND THE 30 DEGREE MARK AT SUNRISE MOST PLACES AND WITH COLD ADVECTION...HOLD NEARLY STEADY WITH 850 MB THERMAL TROF ACRS OUR FA THIS AFTN.

CLOUDS WILL DECREASE TNGT WITH TROF PASSAGE...THO SNOW SHOWERS/FLURRIES MAY CONT EAST EARLY THIS EVE...WILL END HOWEVER AT OOZ TO BE CONSISTENT WITH PREVIOUS FCST. TEMPS TO FALL INTO THE TEENS MOST AREAS.

DK

LONG-TERM (WEDNESDAY THROUGH MONDAY)...

FOR THE MAJORITY OF THIS WEEK...TEMPS WILL GENERALLY RUN AT OR JUST BELOW NORMALS FOR THIS TIME OF YEAR. THIS IS RELATIVELY MUCH COLDER THAN THE TEMPS WE HAVE EXPERIENCED THUS FAR THIS YEAR...AS WE ARE RUNNING 12-13 DEGREES ABOVE NORMAL FOR JANUARY!

WEDNESDAY-THURSDAY...

SFC HIGH PRESSURE AND MAINLY ZONAL FLOW ALOFT WILL DOMINATE WED AND THRS ACROSS THE REGION. WITH LIGHT WINDS AND DRY CONDITIONS...WED AND WED NIGHT WILL BE COLD WITH HIGHS IN THE 30S TO NEAR 40 DOWN SOUTH...AND LOWS IN THE LOW 20S. WILL BE A BIT WARMER ON THRS AS HIGH PRESSURE SLIDES EAST AND SOUTHERLY FLOW COMMENCES.

FRIDAY-MONDAY...

AT THE BEGINNING OF THIS PERIOD...A CLOSED LOW WILL BE LOCATED OVER THE SWRN CONUS. BEFORE THIS MOVES EASTWARD...STRONG NORTHWEST FLOW ACROSS THE NRN U.S. WILL BRING A REINFORCING SHOT OF COLD ARCTIC AIR INTO THE REGION LATE FRIDAY AND INTO SATURDAY. HOWEVER...IF THE CLOSED LOW BECOMES MORE OF AN OPEN WAVE AND MOVES MORE QUICKLY EASTWARD...THIS ARCTIC AIR WOULD BE MORE TO OUR N/NE. CURRENT GRID TEMPS REFLECT A MINOR REINFORCEMENT WHICH LOOKS GOOD SO NO ADJUSTMENTS NEEDED.

ON FRIDAY...THE UPPER JET IS FAIRLY ZONAL AND STRONG...AROUND 160-180KTS. BECAUSE OF THE FAST ZONAL FLOW ALOFT...THINK THE CLOSED LOW OVER SWRN CONUS WILL QUICKLY EJECT OUT INTO THE PLAINS. MOST RECENT MRF MODEL RUNS OPEN UP THIS LOW OVER THE CENTRAL PLAINS BY SUNDAY MORNING. BUT THE TREND FROM THE PAST FOUR (THREE/TWO) RUNS OF THE GFS (GFS ENSEMBLES/ECMWF) HAVE REALLY SPED THIS UP. FOR INSTANCE...THE 06Z GFS RUN FROM YESTERDAY HAD THE UPPER LOW WELL OFF THE SE CALI COAST FRIDAY MORNING. THE 00Z RUN HAS THE OPENING LOW OVER ARIZONA. THE RESULT IS THAT THE SOUTHERN STREAM IS SHOWING QPF GETTING CONTINUALLY CLOSER TO OUR SRN CWA. IF THE MODELS CONTINUE THIS PROGRESSIVE TREND...THEN MAY HAVE TO INSERT PRECIP INTO THE FORECAST SOONER. IN FACT...THE GFS ENSEMBLES SHOW A BIT OF QPF ACROSS OUR SRN CWA ON FRIDAY WITH THE FIRST PUSH OF MOISTURE TOWARD THE REGION. WILL HAVE TO WATCH LATER RUNS TO SEE IF THIS HOLDS. FOR NOW WILL JUST BEEF UP CLOUDS DOWN SOUTH.

SECOND (MAIN) WAVE OF MOISTURE FROM THE SOUTHERN STREAM LOOKS TO OCCUR DURING THE SUNDAY-MONDAY TIMEFRAME WHEN THE UPPER LOW EJECTS OUT INTO THE MIDWEST. AGAIN...IF MODEL TREND CONTINUES...THIS WOULD OCCUR SOONER. RIGHT NOW WE HAVE POPS IN THE GRIDS SUNDAY NIGHT...BUT MAY NEED A SOONER ONSET IF MORE PROGRESSIVE MODEL TREND CONTINUES.

FOR NOW...MADE NO POP CHANGES...BUT ADJUSTED TEMPS DOWN ON WEDNESDAY...CLOSER TO THE OFTEN-TIMES UNJUSTLY IGNORED FWC GUIDANCE.

AL

&&

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

$$


AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
AFDFGF 1011 AM CST TUE JAN 16 2007

.UPDATE...MINIMAL CHANGES TO TODAYS GRIDS/ZONES. 12Z NAM SLIGHTLY UNDERESTIMATED SOME OF THE UPSTREAM WARM AIR ALOFT ACCORDING TO AMDAR SOUNDINGS AT CYQR/CYWG AT 800-850 MB OR SO. BUT POOR MOMENTIVE TRANSFER THIS AFTERNOON/EVENING EXPECTED WITH WINDS THAT HIGH DUE TO DIRECTIONAL VERTICAL SHEAR SO DO NOT EXPECT ANY CONSEQUENCE. BOOSTED CLOUDS A BIT IN ZONES THOUGH GRIDS DON/T LOOK TOO BAD. WILL LIKELY ADJUST THOSE UPWARD TOO WITH LOTS OF MID/HIGH CLOUDS TO STREAM ACROSS NORTH HALF OF CWA.

&&

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

$$

GV


AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSGX 230 PM PST TUE JAN 16 2007

.SYNOPSIS...WEAKENING OFFSHORE FLOW WILL CONTINUE LOCAL GUSTY WINDS THIS EVENING...MAINLY THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. OTHERWISE...FAIR THROUGH WEDNESDAY. UPPER LEVEL LOW PRESSURE WILL BRING PARTLY CLOUDY SKIES WITH A SLIGHT CHANCE OF SHOWERS IN SAN DIEGO COUNTY LATE WEDNESDAY THROUGH THURSDAY. PERIODS OF OFFSHORE FLOW WILL PREVAIL LATE THURSDAY THROUGH THE MIDDLE OF NEXT WEEK FOR DRY WEATHER AND LOCAL GUSTY WINDS. GRADUALLY WARMER DAYS AND NOT AS COLD AT NIGHT.

&&

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

.SHORT TERM (TODAY-FRI)...CLEAR SKIES TODAY. ACARS SOUNDINGS HAD NE WINDS TO 20 KTS IN THE LOW LEVELS AND WLY WINDS ALOFT. WEAKENING OFFSHORE GRADIENTS WITH ABOUT -5 MB SAN-IPL.

LOCAL GUSTY WINDS WILL CONTINUE THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES THIS EVENING BUT THEY SHOULD REMAIN BELOW ADVISORY STRENGTH. SUPPORT FOR THE OFFSHORE FLOW WILL WEAKEN FURTHER LATER TONIGHT WITH DECREASING WINDS. CURRENT INDICATIONS ARE THAT AN UPPER LOW WILL DROP S JUST OFF THE COAST BY LATE WED NIGHT AND THEN MOVE INLAND TO THE S OF SAN DIEGO THU AND INTO AZ BY FRI. HOWEVER...MODELS HAVE BEEN INCONSISTENT WITH THIS SYSTEM AND A SMALL CHANGE IN THE EXACT PATH OF THIS LOW WILL MAKE A BIG DIFFERENCE IN THE LOCAL WEATHER. WILL KEEP SLIGHT CHANCE OF PRECIP CONFINED TO SAN DIEGO COUNTY LATE WED THROUGH THU FOR NOW. OFFSHORE FLOW WILL DEVELOP ON THE W SIDE OF THIS LOW LATE THU AND FRI AND COULD POTENTIALLY BE STRONG. WILL ONLY INDICATE MODERATE OFFSHORE WINDS AT THIS TIME DUE TO LARGE UNCERTAINTIES IN THE FORECAST TRACK OF THE LOW. A LITTLE WARMER DAYS IN MOST AREAS...ESPECIALLY W OF THE MOUNTAINS ON FRI. NOT QUITE AS COLD TONIGHT BUT THERE WILL STILL BE AREAS OF FROST BY MORNING WITH EXCELLENT RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES WITH LOW DEW POINTS. WARMER WED NIGHT AND THEN SLIGHTLY COOLER THU NIGHT.

.LONG TERM (FRI-TUE)...PERIODS OF OFFSHORE FLOW SHOULD PREVAIL FOR DRY WEATHER AND LOCAL GUSTY WINDS AT TIMES...MAINLY THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. GRADUALLY WARMER DAYS. COOL AT NIGHT IN AREAS PROTECTED FROM THE WINDS. THE EXTENDED PERIOD OF DRY OFFSHORE FLOW WILL INCREASE THE FIRE WEATHER HAZARD ONCE AGAIN. THERE MAY ALSO BE PERIODS OF WINDS STRONG ENOUGH FOR LOCAL WIND ADVISORIES OR WARNINGS. &&

.AVIATION... DECREASING OFFSHORE FLOW WILL CONTINUE CLEAR SKIES AND UNRESTRICTED VSBYS THIS AFTERNOON AND EVENING. ONSHORE FLOW WILL RETURN WEDNESDAY MORNING AND UPPER LEVEL LOW PRESSURE APPROACHING FROM THE NORTH WILL BRING SOME CLOUDS AND A SLIGHT CHANCE OF SHOWERS BY WEDNESDAY AFTERNOON. WINDS AT 10K FT WILL BACK TO THE SOUTHWEST AND INCREASE TO 25-35 KT WEDNESDAY AS WELL. OFFSHORE FLOW WILL LIKELY MAKE A RETURN THURSDAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

RED FLAG WARNING UNTIL 6 PM THIS EVENING FOR...ALL MOUNTAINS AND INLAND VALLEY AREAS AND ORANGE COUNTY COASTAL AREA. SEE LAXRFWSGX.

$$

PUBLIC...DVA AVIATION...SCV


AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSGX 930 AM PST TUE JAN 16 2007

.SYNOPSIS...WEAKENING OFFSHORE FLOW WILL CONTINUE LOCAL GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES TODAY...OTHERWISE FAIR THROUGH WEDNESDAY. UPPER LEVEL LOW PRESSURE WILL BRING PARTLY CLOUDY SKIES WITH A SLIGHT CHANCE OF SHOWERS IN SAN DIEGO COUNTY LATE WEDNESDAY THROUGH THURSDAY. PERIODS OF OFFSHORE FLOW WILL PREVAIL LATE THURSDAY THROUGH THE MIDDLE OF NEXT WEEK FOR DRY WEATHER AND LOCAL GUSTY WINDS. GRADUALLY WARMER DAYS AND NOT AS COLD AT NIGHT.

&&

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

.SHORT TERM (TODAY-FRI)...CLEAR SKIES TODAY. ACARS SOUNDINGS HAD NE WINDS TO 20 KTS IN THE LOW LEVELS AND WLY WINDS ALOFT. OFFSHORE GRADIENTS WITH ABOUT -9 MB SAN-IPL.

LOCAL GUSTY WINDS WILL CONTINUE THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES TODAY AND THE CURRENT WIND WARNINGS AND ADVISORIES LOOK OK. THE DRY OFFSHORE FLOW WILL MAINTAIN AN ELEVATED FIRE WEATHER HAZARD THROUGH THIS AFTERNOON. SUPPORT FOR OFFSHORE FLOW WILL WEAKEN THIS AFTERNOON AND TONIGHT. CURRENT INDICATIONS ARE THAT AN UPPER LOW WILL DROP S JUST OFF THE COAST BY LATE WED NIGHT AND THEN MOVE INLAND TO THE S OF SAN DIEGO THU AND INTO AZ BY FRI. HOWEVER...MODELS HAVE BEEN INCONSISTENT WITH THIS SYSTEM AND A SMALL CHANGE IN THE EXACT PATH OF THIS LOW WILL MAKE A BIG DIFFERENCE IN THE LOCAL WEATHER. WILL KEEP SLIGHT CHANCE OF PRECIP CONFINED TO SAN DIEGO COUNTY LATE WED THROUGH THU FOR NOW. OFFSHORE FLOW WILL DEVELOP ON THE W SIDE OF THIS LOW LATE THU AND FRI AND COULD POTENTIALLY BE STRONG. WILL ONLY INDICATE MODERATE OFFSHORE WINDS AT THIS TIME DUE TO LARGE UNCERTAINTIES IN THE FORECAST TRACK OF THE LOW. A LITTLE WARMER DAYS IN MOST AREAS...ESPECIALLY W OF THE MOUNTAINS ON FRI.

.LONG TERM (FRI-TUE)...PERIODS OF OFFSHORE FLOW SHOULD PREVAIL FOR DRY WEATHER AND LOCAL GUSTY WINDS AT TIMES...MAINLY THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. GRADUALLY WARMER DAYS. COOL AT NIGHT IN AREAS PROTECTED FROM THE WINDS. THE EXTENDED PERIOD OF DRY OFFSHORE FLOW WILL INCREASE THE FIRE WEATHER HAZARD ONCE AGAIN. THERE MAY ALSO BE PERIODS OF WINDS STRONG ENOUGH FOR LOCAL WIND ADVISORIES OR WARNINGS. &&

.AVIATION... GUSTY OFFSHORE WINDS WILL CONTINUE TODAY NEAR AND BELOW THE MOUNTAIN PASSES AND CANYONS...THEN WEAKEN THIS AFTN INTO WED. THE STRONGEST WINDS WILL OCCUR THIS MORNING BELOW THE CAJON PASS IN THE INLAND EMPIRE AND NEAR THE SANTA ANA MOUNTAINS. THESE WINDS WILL GENERATE AREAS OF TURBULENCE...STRONG UP AND DOWN DRAFTS...MOUNTAIN WAVES WITH ROTORS AND LOCAL LOW LEVEL WIND SHEAR. LOCAL BLOWING DUST COULD ALSO OCCUR AT TIMES. OTHERWISE VFR CONDITIONS WILL PREVAIL WITH CLEAR SKIES AND UNRESTRICTED VSBYS. WINDS AT 10K FT WILL SHIFT WESTERLY ON WEDNESDAY AND INCREASE TO 25-35 KT AS AN UPPER LEVEL LOW APPROACHES THE AREA.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WARNING UNTIL 3 PM THIS AFTERNOON FOR...THE INLAND EMPIRE...SAN BERNARDINO MOUNTAINS AND SANTA ANA MOUNTAINS. SEE LAXNPWSGX.

WIND ADVISORY UNTIL 3 PM THIS AFTERNOON FOR...ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY VALLEYS...RIVERSIDE COUNTY MOUNTAINS AND SAN DIEGO COUNTY MOUNTAINS. SEE LAXNPWSGX.

RED FLAG WARNING UNTIL 6 PM THIS EVENING FOR...ALL MOUNTAINS AND INLAND VALLEY AREAS AND ORANGE COUNTY COASTAL AREA. SEE LAXRFWSGX.

$$

PUBLIC...DVA AVIATION...SCV


AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
AFDLOT 310 PM CST TUE JAN 16 2007

.DISCUSSION FOR AFTERNOON GRIDS/ZONES...

310 PM CST

LAKE EFFECT SNOW TRENDS MAIN SHORT TERM FOCUS FOR FIRST FEW HOURS TONIGHT.

WEAK VORT/POS TILT UPPER TROF AXIS MOVG EAST OF FCST AREA THIS AFTN. WEAKENING SFC PRES GRADIENT AS SFC HIGH APPRCHG FROM WEST...WITH MODEL TSECTS DEPICTING STRONG AND DEEP SUBSIDENCE DVLPG ATTM. RECENT ACARS SOUNDINGS OUT OF KORD SHOW DIRECTIONAL SHEAR INCREASING THRU ABOUT 750 HPA ALONG WITH DECREASING WIND SPEEDS...AND THIS LACK OF ORGANIZATION RESULTING IN DVLPMNT OF ONE TIME SINGLE BAND LES EVENT NOW TAKING ON MORE OF A THERMALLY FORCED MESO LOW STRUCTURE AS IT FADES. RADAR AND VIS SATELLITE IMGRY FROM LAST HOUR OR SO VERY IMPRESSIVE WITH THIS TRANSITION...LOOKING LIKE A MINI SNOW HURRICANE COMPLETE WITH AN EYE AT 1951Z. IT BEGS TO BE NAMED. WILL HAVE TO CONTEND WITH SNOW SHOWERS ACROSS NORTHERN LAKE/PORTER COUNTIES FOR REMAINDER OF AFTN HOURS AS THIS LES BAND CONTINUES TO DECAY...THOUGH ANTICIPATE THAT COMBINATION OF VERY DRY LOW LVLS...STRENGTHENING AND LOWERING SUBSIDENCE INVERSION AND LOSS OF LLVL CONVERGENCE WILL ALLOW PCPN TO COME TO AN END BY EARLY EVENING.

WITH SFC RIDGE BUILDING ACROSS FCST AREA TNGT...AND SNOW COVER IN PLACE MOST AREAS...SET UP FOR STRONG RADIATIONAL COOLING. LLVL PARCEL TRAJECTORIES FROM NERN IA...WHERE TEMPS DIPPED BLO ZERO THIS MRNG. WILL CONTINUE TO UNDERCUT ALL GUIDANCE NUMBERS FOR MINS OVRNGT...WITH CURRENT GRIDS ACTUALLY LOOKING QUITE GOOD RANGING FROM AROUND -3 NW WHERE DEEPEST SNOW COVER EXISTS...TO NEAR 10 ABOVE SOUTHEAST WHERE SNOW COVER MINIMAL.

MID LVL S/WV RDG MOVS ACROSS FCST AREA WED MORNING...WITH TSECTS AND FCST SOUNDINGS CONTINUING TO DEPICT VERY DRY AMS. SHOULD SEE PLENTY OF SUNSHINE...WITH A LITTLE REBOUND IN TEMPS AS WAA DVLPS IN SWLY FLOW ON BACK SIDE OF SFC RIDGE DURG AFTN. S/WV TROF THEN MOVG OUT OF HIGH PLAINS WED NGT EXPCTD TO GENERATE SOME MID CLOUD COVER AFTER MIDNIGHT AS IT APPROACHES UPPER MS VLY TOWARD MRNG. SWLY LLVL FLOW 10-15 MPH SHOULD HELP TEMPS KEEP FROM DROPPING TOO FAR WED EVENING...THOUGH HAVE STILL GONE A BIT BLO COLDEST FWC NUMBERS.

S/WV MOVES ACROSS FCST AREA THURSDAY...WITH MODELS IN AGREEMENT IN DROPPING SECOND WAVE IN BY LATE IN THE DAY. TSECTS INDICATE LOW LEVELS MOISTEN DURG THE AFTN HOURS AS LLVL COLD ADVECTION STARTS TO KICK IN...THOUGH MOISTURE FAIRLY SHALLOW AND LIFT FOCUSED MORE IN MID LEVELS. WRF/GFS DO ATTEMPT TO KICK OUT SOME VERY LIGHT QPF MAINLY NORTH OF THE FA HOWEVER...SO WILL MAINTAIN CHC OF FLURRIES DURG MAX LLVL CAA/SATURATION THURSDAY NIGHT.

FOR REMAINDER OF FCST...INCREASING SPREAD IN ENSEMBLE SOLUTIONS WITH PATTERN HEADING INTO NEXT WEEKEND. OVERALL TREND SUPPORTS MORE OF A TROUGHINESS ACROSS THE AREA...WITH PERHAPS BEST FOCUS FOR ORGANIZED PCPN ARRIVING SUN/SUN NGT. HPC FAVORING ECMWF/GEM HANDLING OF LATER PERIODS AND WILL NOT ARGUE AT THIS POINT. THUS WILL HAVE CHC LGT SNOW SUN/SUN NGT...THEN CHC SNOW SHOWERS/FLURRIES MONDAY/MON NGT. TEMPS REMAIN RELATIVELY COLD THRU PERIOD...ESPECIALLY IN WAKE OF COLD FRONT THURSDAY NIGHT/FRIDAY...AND WITH PASSAGE OF NEXT SFC HIGH PRES RIDGE FRI NGT/EARLY SAT.

RATZER

&&

.AVIATION...

A SURFACE HIGH OVER EASTERN NEBRASKA WILL DOMINATE THE WEATHER OVER THE MIDWEST AND WESTERN GREAT LAKES. THERE IS A BAND OF LAKE EFFECT SNOW THAT IS JUST EAST OF THE GARY AIRPORT. THIS BAND IS A RESULT OF THE WARM WATER OF LAKE MICHIGAN AND A LOCALIZED LOW LEVEL CONVERGENCE ZONE. AS OF NOW ONLY THE GARY AIRPORT MAY SEE SNOW. THE WIND WILL BE AROUND 320 TO 310 DEGREES AT 10 TO 12 KNOTS. THERE IS A VERY SMALL INVERSION AROUND 1660 FT. THE WIND IS 320 TO 334 DEGREES UP TO 941 MB. THIS FROM THE ACARS SOUNDING AT ORD. BY WEDNESDAY MORNING THE WIND IS FORECAST TO BECOME MORE WEST TO SOUTHWEST BY WEDNESDAY MORNING.

&&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY THROUGH TUESDAY NIGHT.

&&

$$


AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
AFDLOT 1045 AM CST TUE JAN 16 2007

.DISCUSSION FOR MORNING UPDATE...

RADAR INDICATES LES BAND SNAKING BACK TO THE WEST LAST HOUR OR SO...AND WILL LIKELY IMPINGE FARTHER WEST INTO LAKE CO IND DURG NXT HOUR OR SO. RECENT ACARS DESCENT SOUNDINGS FROM KORD INDICATE SOME DIRECTIONAL SHEAR PRESENT IN LOWER 8000 FT...WITH NNE WINDS BETWEEN 3000-7500 FT. THIS HELPING BAND SHIFT TO THE WEST...THOUGH SHORT TERM MODEL GUIDANCE FROM WRF INDICATES A LITTLE MORE OF A SHIFT BACK TO NWLY FLOW IN THIS LAYER LATER THIS AFTERNOON. BASED ON CURRENT RADAR TRENDS HOWEVER...WILL HAVE TO UP POPS...AND MENTION POTENTIAL FOR 1-3 INCHES MAINLY NE LAKE/NORTHERN PORTER THIS AFTN. SOME CLOUD COVER LIKELY TO AFFECT IL SHORE AREAS AS WELL.

ZFP/GRIDS SHORTLY.

RATZER

PREVIOUS DISCUSSION FOR MORNING GRIDS/ZONES...

FOR THE VERY NEAR TERM...THE LIGHT SNOW IS WINDING DOWN OVER THE CWA AS LOW AND MID LEVEL FLOW IS BEGINNING TO TURN MORE ANTICYCLONIC OVER THE REGION. DURING THE PRE-DAWN HOURS THIS MORNING...SOME LINGERING SNOW SHOWERS WILL REMAIN OVER NERN IL...ESPECIALLY OVER ERN LAKE AND COOK COUNTIES IN IL...WHILE SKIES BEGIN TO CLEAR OVER NRN PORTIONS OF THE STATE. CLEARING SKIES WILL SPREAD SEWD DURG THE DAY TODAY. THE EXCEPTION WILL BE OVER NWRN INDIANA WHERE LAKE EFFECT SNOWS WL CONTINUE INTO THE LATE MORNING HOURS. MUCH OF THE LAKE EFFECT SNOW HAS ALREADY BEEN SHUNTED EWD OVER FAR ERN PORTER COUNTY...BUT A LITTLE LIGHT SNOW IS POSSIBLE OVER ERN LAKE COUNTY...INDIANA THIS MORNING. AS THE SFC RIDGE BUILDS EWD TODAY...THE CWA WL SEE CLEARING SKIES...BUT FLOW WL TURN MORE NWLY...SETTING UP A STG COLD ADVECTIVE PATTERN AND TEMPS WILL REACH THE COOLEST LEVELS THAT REGION HAS SEEN IN QUITE SOME TIME. HAVE GENERALLY UNDERCUT TEMP GUIDANCE FOR TODAY`S HIGHS AND TOMORROW MORNING`S LOWS GIVEN THE MOSTLY CLEAR SKIES AND A BIT OF SNOW COVER. TEMPS OVER MUCH OF THE CWA SHOULD DROP BELOW 0F...WITH THE EXCEPTION OF URBANIZED AREAS AND LOCATIONS INVOF LAKE MICHIGAN WHICH SHOULD REMAIN ABV ZERO...BUT WILL STILL BE IN THE SINGLE DIGITS.

BY WEDNESDAY...THE CENTER OF THE SFC HIGH WILL HAVE PASSED EAST OF THE LOCAL AREA AND LOW LEVEL FLOW WL TURN SLY...ALLOWING TEMPS TO MODERATE. THE NEXT CHANCE FOR ANY PCPN WILL NOT BE UNTIL THURSDAY AFTERNOON AND EVENING. THE MODEL GUIDANCE IS IN DECENT AGREEMENT ON HANDLING THE NEXT SYSTEM TO IMPACT THE UPPER MID WEST. THIS SYSTEM HAS ALREADY MOVED ONSHORE INTO THE NRN CANADIAN ROCKIES AND THE MAIN SFC LOW IS EXPECTED TO TRACK ACROSS THE CANADIAN PRAIRIES. THIS LOW SHOULD DRAG A WEAK COLD FRONT ACROSS THE REGION THURSDAY EVENING...BRINGING SOME MORE LIGHT SNOW. BUT GIVEN THE PACIFIC ORIGIN OF THIS SYSTEM...NOT EXPECTING TEMPS TO DROP BLW 0F...BUT SOME SINGLE DIGIT LOW ARE LIKELY FOR SATURDAY MORNING. LOW LEVEL FLOW IS LOOKING CONDUCIVE FOR ADDITIONAL LAKE EFFECT SNOW FOR NWRN INDIANA ON FRIDAY AND SATURDAY...AS FLOW TURNS NWLY BEHIND THE EXITING COLD FRONT AND AND SFC RIDGING BUILDS FROM THE SRN PLAINS THROUGH THE UPPER MISSISSIPPI VALLEY.

KREIN

&&

.AVIATION...

A SURFACE HIGH OVER EASTERN NEBRASKA WILL DOMINATE THE WEATHER OVER THE MIDWEST AND WESTERN GREAT LAKES. THERE IS A BAND OF LAKE EFFECT SNOW THAT IS JUST EAST OF THE GARY AIRPORT. THIS BAND IS A RESULT OF THE WARM WATER OF LAKE MICHIGAN AND A LOCALIZED LOW LEVEL CONVERGENCE ZONE. AS OF NOW ONLY THE GARY AIRPORT MAY SEE SNOW. THE WIND WILL BE AROUND 320 TO 310 DEGREES AT 10 TO 12 KNOTS. THERE IS A VERY SMALL INVERSION AROUND 1660 FT. THE WIND IS 320 TO 334 DEGREES UP TO 941 MB. THIS FROM THE ACARS SOUNDING AT ORD. BY WEDNESDAY MORNING THE WIND IS FORECAST TO BECOME MORE WEST TO SOUTHWEST BY WEDNESDAY MORNING.

&&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY THROUGH TUESDAY NIGHT.

&&

$$


AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
AFDFGF 245 PM CST TUE JAN 16 2007

.SHORT TERM (THROUGH FRI)...ARCTIC AIR IS FINALLY ERODING FROM THE REGION...MOST SLOWLY FOR RED RIVER VALLEY WHERE IT IS 5-10F DEGREES COLDER THAN EITHER SIDE ATTM. CLOUDS PASSING OVER APPEAR TO BE NOT AFFECTING THE WARMING TREND. MODEL SOUNDINGS SHOW THE SURFACE BASED INVERSION TO BE NO MORE THAN 2 KFT DEEP MOST SPOTS WHILE UP TO 10C WARMER ON TOP. 1847Z CYWG AMDAR SOUNDING CONFIRMS THAT AND IS EVEN MORE EXTREME. AM TEMPTED TO FORECAST STEADY/SLOWLY RISING TEMPERATURES TONIGHT BUT THE LIMITED CLOUD COVER ARRIVING FROM THE NORTHWEST WILL BE DISSIPATED AND MOVING ON BY 06Z. EXPECT THE TOO MUCH VERTICAL DIRECTIONAL SHEAR TO ENSURE DECOUPLED LOW LEVEL JET TO MAKE WARM AIR MIXING DOWNWARD TO BE UNLIKELY TONIGHT. SO LEANED ON THE WARMER NAM/NGM MOS GUIDANCE THOUGH SURFACE WARMING WILL OCCUR RELATIVELY QUICK ON WED MORNING.

NEXT SIGNIFICANT 5H SHORTWAVE HAS ENTERED NORTHERN B.C. AND MODELS HAVE SLOWED ITS ARRIVAL TO THU. BOTH NAM/GFS SHOW A NARROW RIBBON OF STRONG ISENTROPIC LIFT AT 280-285K PASSING OVER IN A SECONDARY SHORTWAVE IMMEDIATELY AFTER THE MAIN TROUGH...WHICH SHOWS BETTER POTENTIAL FOR SATURATING THE LOW LEVELS FOR MEASURABLE SNOW. MIXING RATIOS BY THEN DECREASE TO LESS THAN 1 G/KG SO WILL NOT SUGGEST MORE THAN AN INCH THAT DAY. ARCTIC AIR RETURNS THU NIGHT/FRI BUT WILL NOT BE AS COLD AS THE AIR MASS LEAVING ATTM. .LONG TERM (SAT-TUE)... THE OVERALL PATTERN WILL BE DOMINATED BY NW FLOW AND RIDGING INTO THE PACIFIC WEST COAST. THIS WILL MEAN SLIGHT CHANCES FOR LIGHT SNOW...WITH THE STRONGEST CLIPPER TYPE SYSTEM MOVING THROUGH SUNDAY AND SUNDAY NIGHT. THE BEST FORCING WILL BE ACROSS NORTHERN AREAS...BUT BY SUNDAY NIGHT EVEN THE SOUTH WILL SEE A LOW CHANCE FOR LIGHT SNOW. OTHERWISE...EXPECT A DRY PERIOD WITH TEMPS NEAR NORMAL.

&&

.AVIATION... EXPECT VFR CONDITIONS TO PREVAIL AT ALL TAF SITES THROUGH 18Z WED.

&&

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

$$

GV