Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/31/13


AREA FORECAST DISCUSSION
NWS TUCSON AZ
950 PM MST MON JAN 28 2013 .SYNOPSIS...AN UPPER LEVEL SYSTEM OVER WESTERN ARIZONA MONDAY EVENING WILL PUSH EAST ACROSS THE AREA TONIGHT INTO TUESDAY MORNING. EXPECT SCATTERED SHOWERS WITH SNOW LEVELS LOWERING DOWN TO AROUND 3500 FEET. MINOR SNOW ACCUMULATIONS ARE POSSIBLE SOUTH AND EAST OF TUCSON. COLD TUESDAY AND WEDNESDAY MORNING. EXPECT DRY CONDITIONS TO RETURN THE SECOND HALF OF THE WEEK ALONG WITH WARMER TEMPERATURES. && .DISCUSSION...WATER VAPOR IMAGERY SHOWED UPPER LEVEL TROF AXIS EXTENDING FROM THE FOUR CORNERS SW TO JUST WEST OF ROCKY POINT. HAVE HAD SCATTERED LIGHT SHOWERS GOING MOST OF THIS EVENING EAST OF TUCSON WITH ANOTHER BATCH OF SHOWERS WEST SOUTHWEST OF TUCSON. 00Z NAM AND RAP MODELS MOVE UPPER LEVEL TROF EAST OVERNIGHT WITH SHOWERS INCREASING IN AREAL COVERAGE AS TROF ENCOUNTERED A LITTLE MORE PRECIPITABLE WATER. THE SHOWERS THAT WERE OUT BY YUMA AND ROCKY POINT EARLIER THIS EVENING HAS FALLEN APART AS THEY HAVE MOVED INTO SOME DRIER AIR THAT RESIDES OVER CENTRAL PIMA COUNTY WHERE PW VALUES WERE AROUND 0.35" BASED ON GPS. PW VALUES FROM TUCSON EAST ARE NEAR A HALF AN INCH. SNOW LEVEL WILL LOWER TO AROUND 3500 FEET OVERNIGHT WITH UP TO AN INCH ACROSS SANTA CRUZ AND COCHISE COUNTIES. CONTEMPLATED WINTER WEATHER ADVISORY FOR THOSE COUNTIES BUT HELD OFF ON ISSUING ONE. IF RADAR LIGHTS UP IN THE NEXT COUPLE OF HOURS THEN WE MAY HAVE TO HOIST A QUICK ONE. OTHERWISE SENDING OUT ANOTHER UPDATE TO THE FORECAST. SYSTEM OUT OF HERE ON TUESDAY WITH STRONG NW FLOW ON BACK SIDE. MAY SEE PRETTY STRONG WINDS IN NW-SE ORIENTED VALLEYS TUESDAY AFTERNOON. SPEEDS MAY END UP NEAR ADVISORY CRITERIA. && .AVIATION...BKN-OVC CLOUDS 5-8K FT AGL AND MTNS OBSCD...WITH SCT -SHRA/SHSN THRU TONIGHT...THEN SKIES GRADUALLY CLEARING TUESDAY MORNING. WINDS GENERALLY WLY-SWLY 12-22 KTS WITH HIGHER GUSTS EAST OF TUCSON THROUGH 06Z TUESDAY...THEN MAINLY LESS THAN 10 KTS THROUGH TUESDAY MORNING FROM KTUS WESTWARD AND 10-20 KTS ACROSS EASTERN AREAS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS. SCATTERED SHOWERS AND BREEZY CONDITIONS INTO THIS EVENING. DRY WEATHER TUESDAY BUT WINDY ESPECIALLY IN THE UPPER GILA RIVER VALLEY. TEMPERATURES WILL BEGIN TO MODERATE WEDNESDAY WITH DRY CONDITIONS CONTINUING. && .TWC WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY TIL 11 PM TONIGHT FOR AZZ510 && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
355 PM MST WED JAN 30 2013 .SHORT TERM...STRONG NORTHWEST FLOW ALOFT OVER AREA WITH OROGRAPHICS CONTINUING ACROSS MOUNTAINS. WEB CAMS INDICATE SNOW CONTINUING ACROSS MOUNTAINS...THOUGH HAS SHOWN SOME SIGNS OF DECREASING DURING THE PAST FEW HOURS. STABILITY HAS BEEN LIMITED...WHICH HAS HINDERED THE HEAVIER SNOW RATES. STILL..WINDS BEEN QUITE GUSTY ACROSS THE RIDGES...WITH A RECENT GUST TO 71 MPH ATOP BERTHOUD PASS WHILE OTHER GUSTS WERE MAINLY IN THE 50S. THE WINDS WERE CREATING AREAS OF BLOWING SNOW ACROSS THE MOUNTAIN PASSES. GUSTY WINDS ALSO OCCURRING IN AND NEAR FOOTHILLS WITH GUSTS MAINLY IN THE 40S. ACROSS PLAINS WEAK MESOCYCLONE SLIDING SOUTH ACROSS MORGAN COUNTY KEEPING GUSTY WINDS FROM SPREADING EAST ACROSS URBAN CORRIDOR. FLOW ALOFT REMAINS STRONG TONIGHT AND INCREASES SLIGHTLY AS SHOWN BY RAP CROSS SECTIONS. AIRMASS TO REMAIN QUITE MOIST ACROSS THE MOUNTAINS ALONG WITH CONTINUED OROGRAPHICS AND SNOWFALL. STABILITY SHOULD IMPROVE OVERNIGHT... HELPING WITH SNOWFALL RATES. ADDITIONAL 3 TO 6 INCHES STILL POSSIBLE ON FAVORED WEST FACING SLOPES WITH LESSER AMOUNTS ELSEWHERE. MODEL CROSS SECTIONS SHOW WEAK MOUNTAIN WAVE DEVELOPING OVERNIGHT WHICH WILL HELP TO INCREASE WINDS. GUSTS AROUND 70 MPH POSSIBLE ALONG THE HIGHER RIDGES...WITH GUSTS UP TO 60 MPH ALONG THE FOOTHILLS. THE GUSTY WINDS WILL CONTINUE TO CREATE CONSIDERABLE BLOWING SNOW OVER THE MOUNTAIN PASSES WITH POSSIBLE WHITE OUT CONDITIONS ABOVE TIMBERLINE. ACROSS PLAINS...WINDS TO BE A BIT GUSTY NEAR THE FOOTHILLS AND WYOMING BORDER WITH LESS WIND ELSEWHERE. MODELS CONTINUE TO SHOW AN AREA OF LIGHT SNOW DEVELOPING ALONG THE WYOMING BORDER TONIGHT IN VICINITY OF UPPER JET. OTHERWISE...DRY CONDITIONS TO PREVAIL. ON THURSDAY...STRONG NORTHWEST FLOW ALOFT TO CONTINUE THOUGH MODEL CROSS SECTIONS INDICATE MOISTURE ACROSS MOUNTAINS DECREASING BY THE AFTERNOON AS STABILITY INCREASES. STILL DECENT ORORGRAPHICS IN PLACE FOR MUCH OF THE DAY ALONG WITH GUSTY WINDS. SHOULD SEE SNOW GRADUALLY DECREASE DURING THE DAY THOUGH THERE WILL STILL BE QUITE A BIT OF BLOWING SNOW. WILL MAINTAIN THE WARNING THROUGH THE DAY THOUGH ADDITIONAL SNOWFALL SHOULD BE LIGHT. WINDS TO BE A BIT GUSTY IN AND NEAR THE FOOTHILLS AS A WEAK SURFACE TROUGH IS EXPECTED TO DEVELOP. FURTHER EAST...MODELS CONTINUE TO SHOW A WEAK COLD FRONT MOVING INTO THE NORTHEAST CORNER. WITH UPPER JET IN VICINITY... THERE COULD BE A SLIGHT CHANCE OF LIGHT SNOW IN THE FAR NEAR THE WYOMING BORDER. OTHERWISE DRY CONDITIONS WILL PREVAIL. .LONG TERM...A RATHER BENIGN WEEK OF WEATHER IS EXPECTED AFTER THE SNOW SHOWERS CLEAR OUT OF THE MOUNTAINS THURSDAY NIGHT. ON THURSDAY EVENING...A FEW SNOW SHOWERS MAY BE LINGERING...BUT THEY WILL BE ON THE DECREASE AS SUBSIDENCE OVER THE STATE INCREASES. DRY...NORTHWESTERLY FLOW ALOFT IS FORECAST TO CONTINUE THROUGH THE PERIOD AS AN UPPER RIDGE REMAINS ANCHORED OFF THE WEST COAST AND A DEEP TROUGH CONTINUES OVER THE EASTERN UNITED STATES. THE ECMWF AND GFS ARE IN GOOD AGREEMENT THROUGH THE WEEKEND...BUT AT THE END THE TWO MODELS HAVE DIFFERENT IDEAS ABOUT A TROUGH THAT DEVELOPS OFF THE CALIFORNIA COAST. IF A TROUGH DEVELOPS...IT IS NOT EXPECTED TO MOVE INTO THE CENTRAL ROCKIES UNTIL THE MIDDLE OF NEXT WEEK. TEMPERATURES SHOULD GRADUALLY MODERATE THROUGH THE UPCOMING FORECAST PERIOD AS THE NORTHWEST FLOW ALOFT CONTINUES. && .AVIATION... WINDS HAVE BECOME LIGHT NORTHEAST AT DEN DUE TO WEAK MESOCYCLONE OVER MORGAN COUNTY. GUSTY WEST TO NORTHWEST WINDS CONTINUE AT APA AND BJC. WINDS TO BECOME NORTHWEST AT DEN BY 00Z AS MESOCYCLONE SHIFTS EAST INTO WASHINGTON COUNTY. AFTER 03Z...WINDS SHOULD SHIFT TO THE SOUTHWEST AT DEN AND APA AS DRAINAGE FLOW DEVELOPS WITH SPEEDS AROUND 12 KTS. WINDS TO REMAIN WEST TO NORTHWEST AT BJC THROUGH THE EVENING AND OVERNIGHT...WITH SOME GUSTS TO 40 KTS POSSIBLE AFTER 06Z. ON THURSDAY...WINDS TO BECOME NORTHWEST AND WEAKEN ACROSS THE AREA AFTER 16Z. SOME GUSTS TO 25 KTS WILL BE POSSIBLE AT BJC. VFR TO PREVAIL. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 5 PM MST THURSDAY FOR COZ031-033-034. && $$ SHORT TERM...D-L LONG TERM....DANKERS AVIATION...D-L
AREA FORECAST DISCUSSION
NWS PUEBLO CO
302 PM MST TUE JAN 29 2013 .SHORT TERM... (TONIGHT AND WEDNESDAY) SNOW HAS BEEN WINDING DOWN ACROSS THE SOUTHEAST MOUNTAINS/I-25 CORRIDOR AS FOCUS FOR HEAVIER SNOW SHIFTS EASTWARD ACROSS THE PLAINS AHEAD OF THE MAIN UPPER TROF AXIS. SNOWFALL REPORTS THAT HAVE COME IN SO FAR HAVE INDICATED 2 TO 5 INCHES ACROSS THE LOWER EASTERN SLOPES OF THE SE MTS AND ADJACENT I-25 CORRIDOR. GOBBLERS KNOB WEB CAM IN SOUTHERN PROWERS COUNTY STARTING TO PICK UP SOME HEAVIER SNOW AS OF 2 PM...WITH GROUND NEARLY SNOW COVERED. FOCUS FOR HEAVIER SNOW WILL CONTINUE TO SHIFT SOUTH AND EASTWARD THROUGH THE LATE AFTERNOON AND EARLY EVENING. STILL THINKING GENERALLY 1-3 INCHES OF SNOWFALL FOR THE SOUTHEAST PLAINS GENERALLY TO THE SOUTH AND EAST OF KLHX. THE HEAVIEST WILL FALL ALONG THE NORTHERN SLOPES OF THE RATON MESA AND ACROSS BACA COUNTY. WHILE 18Z NAM CONTINUES TO DEPICT A BAND OF HEAVIER SNOW AMOUNTS OF 1 TO 3 INCHES ACROSS BACA/LAS ANIMAS...THE RAP HAS BACKED OFF ON THIS AND NOW PLACES THE BAND WELL TO THE SOUTH OF THE AREA. HRRR ALSO APPEARS TO HAVE BACKED OFF ON SNOW AMOUNTS ACROSS BACA COUNTY...SO WILL HOLD OFF ON ISSUING ANY HIGHLIGHTS AT THIS POINT AND STICK WITH THE GENERALLY 1-3 INCH AMOUNTS. WITH INSTABILITY STILL IN PLACE WITHIN THE TROF AXIS...THERE STILL COULD BE SOME LINGERING SNOW SHOWERS BEHIND THE TROF AXIS THROUGH THE EVENING...THUS WILL KEEP SCATTERED POPS IN AND NEAR THE MOUNTAINS UNTIL 06Z. MEANWHILE...ALTHOUGH HEAVIER SNOW WILL BE TAPERING OFF...NORTHWESTERLY OROGRAPHICS AND INCREASING WINDS ALOFT ON THE BACK SIDE OF THE UPPER TROF WILL KEEP WIDESPREAD LIGHT TO MODERATE SNOW GOING ALONG THE SAWATCH AND MOSQUITO RANGES THROUGH THE NIGHT...WITH THE WIND CAUSING SOME AREAS OF BLOWING SNOW. WITH TEMPERATURES FALLING INTO THE NEGATIVE READINGS OVERNIGHT...MAY ALSO SEE SOME WIND CHILL ADVISORY READINGS IN THE -25 TO -34 DEGREE RANGE. PREVIOUS SHIFT ISSUED A LONG DURATION WINTER WEATHER ADVISORY FOR THIS AREA...AND THIS STILL LOOKS GOOD...THOUGH HIGHEST IMPACT MAY BE DUE TO MORE BLOWING SNOW INITIALLY. WILL ADD MENTION OF THE WIND CHILL VALUES TO THE UPDATED WSW. MAY ALSO SEE WIND CHILL ADVISORY VALUES ACROSS THE HIGHER ELEVATIONS OF THE EASTERN SAN JUAN AND LA GARITA MOUNTAINS...THOUGH GIVEN THE SPOTTY NATURE WILL HOLD OFF ON ISSUING A WIND CHILL ADVISORY AT THIS POINT. TRAILING SHORTWAVE ENERGY DROPPING IN ON WEDNESDAY SHOULD ENHANCE SNOWFALL AGAIN ACROSS THE CENTRAL MOUNTAINS WEDNESDAY AFTERNOON. SHOULD SEE 24 HOUR ACCUMULATIONS OF 2 TO 8 INCHES THROUGH WEDNESDAY AFTERNOON FOR THIS AREA. ELSEWHERE WX WILL BE PRIMARILY DRY. GUSTY NORTHWEST 20-40 MPH WINDS WILL MIX DOWN INTO THE LOWER ELEVATIONS AND ADJACENT I-25 CORRIDOR WEDNESDAY AFTERNOON WHERE GUSTS TO AROUND 20-30 MPH WILL BE POSSIBLE. SNOW COVER WOULD BODE FOR KEEPING TEMPERATURES ON THE COOL SIDE OF GUIDANCE TOMORROW...THOUGH WITH THE WINDS AND SOME MIXING...THEY SHOULD MANAGE TO WARM ABOVE FREEZING ACROSS MOST OF THE PLAINS. LEANED MAX TEMPS TOWARDS THE COOLER SIDE OF GUIDANCE FOR NOW. MOUNTAIN AREAS WILL SEE HIGHS GENERALLY IN THE TEENS AND 20S...WITH SOME LOWER 30S ACROSS THE VALLEY AREAS. -KT .LONG TERM... (WEDNESDAY NIGHT THROUGH TUESDAY) WEDNESDAY NIGHT AND THURSDAY...BRISK NW FLOW ALOFT CONTINUES ACROSS THE REGION THROUGH THURSDAY...WITH MODELS AGREEING ON KEEPING A NEARLY CONSTANT THREAT OF LIGHT TO MODERATE PCPN OVER THE CENT MTS THROUGH THE EVE. THOUGH NEW SNOW AMOUNTS WILL ACCUMULATE TO 12 TO 16 INCHES BY THURSDAY AFTN...ANOTHER REAL CONCERN WILL BE THE STRONG WINDS ALOFT THAT WILL BE EXPERIENCED ACROSS THE HIGHER TERRAIN. A 100 KT CORE OF THE UPPER JET NOSES INTO THE NW QUAD OF COLORADO THROUGH WEDNESDAY NIGHT...BEFORE MOVING EAST AND WINDS WEAKEN BY MIDDAY THURSDAY. THEREFORE...ONGOING WINTER WX ADV FOR THE HIGHER ELEVATIONS OF LAKE AND CHAFFEE COUNTIES LOOKS GOOD. MAX TEMPS ON THURSDAY ARE EXPECTED TO REBOUND INTO THE 50S FOR THE PLAINS...30S AND 40S FOR THE HIGH VALLEYS. FRIDAY AND SATURDAY...TEMPORARY RIDGING ACROSS THE DESERT SW AND COLORADO TO START THE WEEKEND...WITH DRY AND MILD CONDITIONS EXPECTED. MODELS DO INDICATE A MINOR UPPER DISTURBANCE ROLLING ACROSS THE ROCKY MT REGION...BUT CONTINUE TO KEEP THIS FEATURE JUST NORTH OF THE CWA AND FEEL THAT THE ONLY EFFECT WILL BE AN INCREASE IN HIGH LEVEL CLOUDINESS. WINDS REMAIN SOMEWHAT LIGHT...SO NO APPRECIABLE CHANGE IN THE TEMPS IS EXPECTED. SUNDAY THROUGH TUESDAY...AN UPPER LOW PRES SYSTEM JUST OFF THE S CA COAST WILL START PUSHING A PLUME OF WARMER PACIFIC MOISTURE UP ACROSS AZ AND THE 4 CORNERS STARTING ON SUNDAY. AT THE SAME TIME...AN UPPER DISTURBANCE DROPPING DOWN ACROSS MT AND WY WILL ACT UPON THIS MOISTURE TAP AND SQUEEZE OUT SOME ISOLATED SHOWERS ALONG THE CONTDVD LATE SUNDAY. AS THIS FEATURE MOVES EAST AND OUT OF THE AREA MONDAY...PCPN CHANCE DIMINISH. HOWEVER...LATE MONDAY THE LOW OFF THE WEST COAST STARTS TO FILL AND MOVE ONSHORE...BRINGING A SHOT FOR PCPN ONCE AGAIN TO THE CONTDVD STARTING TUESDAY MORNING. MOORE && .AVIATION... VFR CIGS ACROSS THE TAF SITES WILL GRADUALLY DIMINISH THROUGH THE EVENING. THERE COULD BE A LIGHT SNOW SHOWER IN THE VICINITY OF KCOS THIS EVENING...THOUGH CHANCE LOOKS TOO REMOTE TO WARRANT INCLUSION IN THE TAF AT THIS POINT. WINDS WILL DECREASE TO UNDER 6 KTS AT KPUB AND KALS OVERNIGHT...THOUGH KCOS MAY CONTINUE TO SEE SOME ENHANCED NORTH WINDS IN THE 5-10 KT RANGE THROUGH THE NIGHT. MEANWHILE...IFR TO LIFR CIGS AND VIS IN -SHSN WILL CONTINUE ALONG THE CONTDVD...PARTICULARLY ACROSS THE CENTRAL MTS...RESULTING IN WIDESPREAD MTN OBSCURATIONS. MVFR TO BRIEFLY IFR CIGS WILL CONTINUE ACROSS THE SOUTHEAST PLAINS THROUGH EARLY EVENING BEFORE THE SNOW BAND PUSHES SOUTHEAST OF THE AREA OVERNIGHT. ON WEDNESDAY...VFR CIGS/VIS EXPECTED FOR THE TAF SITES...WITH SOME BREEZY WEST TO NW WINDS 10-15 KTS POSSIBLE AT KCOS AND KPUB DURING THE AFTERNOON. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THURSDAY FOR COZ058-060. && $$ 31/27
AREA FORECAST DISCUSSION...UPDATED
NWS PUEBLO CO
1119 AM MST TUE JAN 29 2013 .UPDATE... QUICK UPDATE TO INCREASE POPS FARTHER EAST AND TO DECREASE POPS TO THE NORTH AND WEST. DISTINCT BACK EDGE TO THE SNOW BAND IS DROPPING SOUTHWARD INTO NRN PUEBLO COUNTY...AND SNOW IS LIGHTENING UP ALONG THE LEE OF THE WET MOUNTAINS. ALREADY HAD REPORTS OF 1 TO 3 INCHES FOR EL PASO AND PUEBLO COUNTIES...WITH AROUND 5 INCHES REPORTED AT BEULAH...AND 4 INCHES AROUND 5 MILES WEST OF WALSENBURG. THE LOWER EASTERN SLOPES OF THE SE MTS...WETS AND SANGRES...COULD PICK UP ANOTHER INCH OR TWO...WITH GREATEST AMOUNTS ACROSS THE SOUTHERN SANGRES AREAS DURING THE EARLY AFTERNOON. MAIN CONCERN IS SHIFTING TO THE SOUTHEAST PLAINS. SOME OF THE HIGH RES SHORT RANGE MODELS DEPICT A BAND OF 2 TO 4 INCHES ACROSS BACA COUNTY LATER THIS AFTERNOON...THOUGH RAP IS KEEPING THIS AXIS TO THE SOUTH OF THE AREA. COULD HIT LOW END ADVISORY THRESHOLDS OUT THAT WAY...BUT BREVITY OF THE STORM MAY LIMIT SNOWFALL ACCUMS TO JUST BELOW CRITERIA AS THE SYSTEM PULLS EAST OF THE AREA AFTER 00Z. LAPSE RATES ARE QUITE IMPRESSIVE...WHICH IS WHY SNOWFALL HAS BEEN HEAVY AT TIMES. INSTABILITY IS ALWAYS A WILD CARD IN SCENARIOS LIKE THIS ONE AND CAN RESULT IN LOCALLY HEAVY SNOWFALL AMOUNTS. WILL CONTINUE TO MONITOR AND MAKE ADJUSTMENTS TO THE FORECAST AS NEEDED. -KT && .PREV DISCUSSION... /ISSUED 1030 AM MST TUE JAN 29 2013/ AVIATION... FOR KCOS...SNOW HAS ENDED. CONDITIONS WILL IMPROVE TO VFR. KPUB...SNOW EXPECTED TO CONTINUE THROUGH ABOUT 19Z AND THEN DIMINISH. IFR/LIFR UNTIL AROUND 19Z...AND THEN GRADUALLY IMPROVING TO VFR. KALS...SNOW SHOWERS WILL BE POSSIBLE THROUGH THE DAY WITH POSSIBLE MVFR CONDITIONS. SNOW SHOWERS WILL CONTINUE IN THE MOUNTAINS WITH ISOLATED TO SCATTERED MVFR/IFR/LIFR CONDITIONS. THE HEAVIEST SNOW IS YET TO COME FOR THE FAR SOUTHEAST COLORADO PLAINS...SOUTH AND EAST OF PUEBLO. SNOWFALL EXPECTED TO INCREASE IN THAT AREA THROUGH THE AFTERNOON WITH SNOW...BLOWING SNOW AND AT LEAST A FEW INCHES OF ACCUMULATION POSSIBLE. EXPECTING MVFR/IFR/LIFR CONDITIONS TO DEVELOP ACROSS THE FAR SOUTHEAST PLAINS THIS AFTERNOON AS SNOWFALL MOVES INTO THE AREA. LW PREV DISCUSSION... /ISSUED 341 AM MST TUE JAN 29 2013/ SHORT TERM... (TODAY AND TONIGHT) .SOME SNOW FOR THE PLAINS... .SNOW CONTINUING ACROSS THE C MTNS... CURRENTLY... FULL LATITUDE TROUGH EXTENDS FROM NORTHERN WY S-SWD INTO S ARIZ. THIS TROUGH WAS MOVING STEADILY EAST. LOCALLY ON THE PLAINS...ECHOES WERE INCREASING ACROSS EL PASO COUNTY WITH HIGH LEVEL ECHOES DEVELOPING OVER THE FAR E PLAINS. SKIES WERE GENERALLY CLOUDY OVER THE ENTIRE REGION WITH LOW CLOUDS ALONG THE GREATER I-25 CORRIDOR REGION. TODAY... IT PROMISES TO BE AN INTERESTING DAY...HOW INTERESTING WILL BE THE MAIN QUESTION. I AM CONFIDENT WE WILL SEE SNOW ACROSS THE PLAINS TODAY. MODELS IN FAIRLY GOOD AGREEMENT WITH SNOW DEVELOPING THIS MORNING OVER THE PALMER DIVIDE (AND THIS IS VERIFYING) AND MOVING S/DEVELOPING OVER THE EASTERN PLAINS AFTER SUNRISE. SHORTER RANGE MODELS ARE NOW DEVELOPING A SHARP TROUGH AXIS/WEAK CLOSED LOW AT 700 MB OVER THE FAR SE PLAINS REGION OF CO. THIS WILL SET UP STRONGER LLVL CONVERGENCE OVER THE E PLAINS AND THIS SHOULD ALLOW A DECENT BAND OF SNOW TO DEVELOP...WITH THE HEAVIEST PRECIP LIKELY EXTENDING FROM EADS SSW TOWARDS LAS ANIMAS COUNTY. ADDITIONALLY...WITH THE SHARP LLVL TROUGH...WINDS AT 700 GO NORTHEASTERLY AND THIS SHOULD FAVOR THE RATON MESA/S MTNS LATER TODAY. THE COS/PUB AREAS WILL SEE ITS BEST CHANCE OF SNOW FROM NOW THROUGH LATE MORNING. AS FOR ACCUMULATIONS...WE COULD SEE 1-2" IN AREAS IN THE PUB/COS AREA. IN MATTER OF FACT...SOME OF THE HIGH RES MODELS ARE SHOWING MORE SNOW FOR THE PUB AREA THAN THE SPRINGS. FOR THE FAR E PLAINS...I PUT IN 1-2"...I AM CONCERNED THERE MAY BE LOCALLY MORE IF THE SNOW COMES DOWN HEAVY ENOUGH. RATON MAY SEE 1-3". THESE VALUES ARE SOMEWHAT UNCERTAIN...ESPECIALLY FOR THE FAR E PLAINS. IF THE BAND SETS UP AND STAYS IN PLACE...WE COULD SEE LOCALLY HIGHER AMOUNTS OVER THE FAR E PLAINS...ESPECIALLY IN AREAS FROM KIOWA COUNTY S-SE INTO LAS ANIMAS COUNTY. SNOW OVER THE CONTDVD WILL DECREASE THIS MORNING...ESPECIALLY ACROSS THE SW MTNS. THE SNOW WILL PICK UP AGAIN ACROSS THE C MTNS THIS AFTERNOON. TONIGHT... PLAINS WILL BE DRY. THERE MAY BE A FEW LINGERING SHOWERS EARLY THIS EVENING OVER THE FAR E PLAINS...BUT THEY SHOULD MOVE OUT INTO KS PRETTY QUICKLY. IN ADDITION...WE MAY SEE SOME LINGERING SNOW SHOWERS OVER THE PALMER DIVIDE DURING THE EVENING HOURS. FOR THE C MTNS...SNOW WILL CONTINUE TO INCREASE. WE WILL BE ISSUING ADDITIONAL HILITES FOR THIS REGION AFTER 5 AM THIS MORNING. WE ARE LEANING TOWARDS A LONG DURATION HILITE STARTING LATER TODAY AND LASTING POSSIBLY INTO LATE WEEK (THU?). FAVORABLE NW FLOW WILL KEEP THE SNOW MACHINE GOING FOR AT LEAST A COUPLE OF DAYS ACROSS THE C MTN REGION. /34 LONG TERM... (WEDNESDAY THROUGH TUESDAY) MODELS IN GOOD AGREEMENT HEADING INTO THE WEEKEND WITH DIFFERENCES BY EARLY NEXT WEEK. TRENDED THE FORECAST WITH THE ECMWF WHICH SEEMS TO HAVE A BIT BETTER SUPPORT OF THE ENSEMBLE MEMBERS. THE UPPER LEVEL TROUGH SITTING OVER EASTERN COLORADO WEDNESDAY MORNING WILL QUICKLY SHIFT EAST INTO THE MISSOURI VALLEY BY WEDNESDAY AFTERNOON. BOTH THE ECMWF AND NAM HAVE SNOW COMING TO AN END OVER THE PALMER DIVIDE AND SOUTHERN SANGRE DE CRISTO RANGE BEFORE SUNRISE WEDNESDAY...WHILE THE GFS WANTS TO HANG ONTO LINGERING SNOW OVER THESE AREAS THROUGH MUCH OF WEDNESDAY MORNING. GIVEN THAT THE MODELS SEEM TO FAVOR DRY CONDITIONS...HAVE THE EASTERN MOUNTAINS AND PALMER DRY BY WEDNESDAY MORNING. ONCE THE UPPER TROUGH SHIFTS EAST WEDNESDAY AFTERNOON...THE REGION WILL BE UNDER BROAD NORTHWESTERLY FLOW. EXPECT A PROLONGED PERIOD OF LIGHT TO MODERATE SNOWFALL ACROSS THE CENTRAL MOUNTAINS THROUGH THURSDAY. WEST FACING SLOPES WILL LIKELY SEE A GOOD 4 TO 8 INCHES WEDNESDAY THROUGH THURSDAY WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WINTER WEATHER HIGHLIGHTS WILL LIKELY BE ISSUED FOR THE HIGHER ELEVATIONS OF THE CENTRAL MOUNTAINS LATER THIS MORNING. TEMPERATURES WILL BE COOL ON WEDNESDAY WITH 40S FOR THE LOWER ELEVATIONS BEFORE REBOUNDING INTO THE MID 50S ON THURSDAY. NORTHWEST FLOW TURNS MORE WESTERLY THURSDAY NIGHT AHEAD OF A WEAK SHORTWAVE TROUGH DROPPING SOUTH OUT OF THE NORTHERN ROCKIES. THIS SHOULD EFFECTIVELY SHUT DOWN SNOWFALL OVER THE CENTRAL MOUNTAINS BY THURSDAY EVENING. MODELS HANDLE THE WEAK SHORTWAVE DIFFERENTLY. THE GFS DROPS THE WAVE SOUTH ACROSS COLORADO ON FRIDAY WITH A PERIOD OF LIGHT SNOWFALL ACROSS THE HIGHER ELEVATIONS FRIDAY EVENING. THE ECMWF PROVIDES A GLANCING BLOW ACROSS NORTHERN COLORADO AND KEEPS THE REGION DRY. GIVEN THE CONSISTENCY FROM RUN TO RUN OF THE ECMWF...HAVE TRENDED WITH IT...WITH DRY CONDITIONS ON FRIDAY AND FRIDAY NIGHT. FOR THE LATER HALF OF THE FORECAST PERIOD...HAVE TRENDED WITH THE ECMWF WHICH HAS BETTER SUPPORT FROM THE ENSEMBLES. HIGH PRESSURE WILL SHIFT EAST ACROSS COLORADO SATURDAY INTO SUNDAY BEFORE A WEAK TROUGH OUT OF THE PACIFIC NORTHWEST TRACKS ACROSS THE REGION SUNDAY NIGHT INTO MONDAY MORNING. TEMPERATURES SHOULD WARM NICELY FOR THE WEEKEND WITH AT LEAST UPPER 50S TO LOWER 60S ACROSS THE PLAINS. THERE IS VERY LITTLE MOISTURE TO WORK WITH AND THE FORECAST LOOKS TO BE DRY AT THIS POINT. HIGH PRESSURE WILL THEN REBUILD ACROSS THE ROCKIES BY TUESDAY WITH CONTINUED DRY AND MILD WEATHER. IT SHOULD BE NOTED THAT THE GFS BRINGS A TROUGH INTO THE REGION LATE SATURDAY THROUGH SUNDAY NIGHT WITH INCREASED CHANCES FOR SNOWFALL OVER THE MOUNTAIN AREAS...SPREADING EAST INTO THE PLAINS AS THE SYSTEM PASSES BY. THERE SEEMS TO BE LITTLE SUPPORT FOR THIS SOLUTION...AND A QUICK LOOK AT THE NEW 06Z RUN HAS REALLY BACKED OFF ON PRECIPITATION COMPARED TO THE 00Z SOLUTION AND LOOKS MORE LIKE THE ECMWF. 88 AVIATION... FOR KCOS...PERIODS OF SNOW WILL OCCUR UNTIL ABOUT LATE MORNING THEN VFR. LIGHT ACCUMS...ABOUT AN INCH OR SO...ARE POSSIBLE. IFR CONDITIONS WILL OCCUR IN STEADY PRECIP. WINDS SHOULD NOT BE TOO MUCH OF AN ISSUE...NNE AT 10-15 KTS DURING THE SNOW. VFR AFTER NOONTIME. KPUB...COULD SEE SOME SNOW THIS MORNING AND EARLY AFTERNOON. OVC MVFR/IFR LIKELY. SHOULD CLEAR UP BY EARLY AFTERNOON WITH VFR CONDITIONS. KALS...SNOW SHOWERS WILL BE POSSIBLE THROUGH THE DAY WITH POSSIBLE MVFR CONDITIONS. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 5 PM MST THURSDAY FOR COZ058-060. && $$ 31/27
AREA FORECAST DISCUSSION
NWS MIAMI FL
855 PM EST WED JAN 30 2013 .UPDATE... COLD FRONT MOVING THROUGH THE PANHANDLE THIS EVENING WILL APPROACH SOUTH FLORIDA AFTER MIDNIGHT TONIGHT. LOCAL WRF AND HRRR SHOW A THIN LINE OF SHOWERS APPROACHING THE NORTHWEST PORTIONS OF THE CWA AROUND 09Z TONIGHT...AND THEN THE LINE SLOWLY MOVING THROUGH THE REST OF THE REGION THROUGH THE MORNING HOURS. THE CURRENT POP GRIDS HANDLE THIS WELL...SO NO UPDATES ARE NEEDED. TEMPERATURES TONIGHT WILL BE WARM...WITH LOWS NEAR 60 TO THE LOWER 70S. ALTHOUGH WINDS WILL LIKELY FALL BELOW SCA CRITERION OVER THE LOCAL GULF WATERS THIS EVENING...KEPT THE SCA GOING AS WINDS WILL INCREASE LATE TONIGHT BEHIND THE FRONT. FOR THE ATLANTIC WATERS...WILL CANCEL THE SCA SINCE THE WINDS HAVE FALLEN TO AROUND 10-15 KNOTS AND WINDS ARE NOT EXPECTED TO INCREASE TO SCA CONDITIONS AGAIN UNTIL AFTER 18Z ON THURSDAY. && .PREV DISCUSSION... /ISSUED 628 PM EST WED JAN 30 2013/ AVIATION...VFR WILL PREVAIL, BUT A FEW SHOWERS/BRIEF MVFR WILL BE POSSIBLE ALONG COLD FRONT EXPECTED TO MOVE ACROSS KAPF AT AROUND SUNRISE, THEN THE EAST COAST TERMINALS BY MID MORNING THU. CURRENT WIND OBS ARE SSE BUT ACARS DATA SHOWS SSW JUST ABOVE THE SFC. VEERED WINDS THROUGH THE NIGHT TO SSW AS FRONT APPROACHES, THEN TURNED WINDS NW BEHIND THE COLD FRONT THU. GUIDANCE SUGGEST CLOUDS LIKELY WILL HANG TOUGH BEHIND THE FRONT FOR THE EAST COAST TERMINALS THROUGHOUT THE DAY THU. BEST PROSPECTS FOR SHOWERS/BRIEF MVFR CIGS LOOK TO BE 10-15Z THU, EXCEPT 06-12Z AT KAPF. THX CWSU MIAMI FOR COORDINATION. /GREGORIA PREV DISCUSSION... /ISSUED 237 PM EST WED JAN 30 2013/ SYNOPSIS... A COLD FRONT WILL MOVE THROUGH SOUTH FLORIDA THURSDAY MORNING...ENDING THE ABOVE NORMAL TEMPERATURES AND BRINGING A SLIGHT CHANCE OF SHOWERS AS IT PASSES. HIGH PRESSURE BUILDS IN FRIDAY THROUGH THE WEEKEND...WITH SLIGHTLY BELOW NORMAL TEMPERATURES RISING TO NEAR SEASONAL AVERAGES BY EARLY NEXT WEEK. SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... BREEZY CONDITIONS IN PLACE THROUGH FLORIDA AS PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE OVER WESTERN ATLANTIC AND SURFACE COLD FRONT MOVING EASTWARD THROUGH THE DEEP SOUTH INCREASES. SOUTH WINDS HAVE GUSTED TO NEAR 30 KTS...JUST BELOW WIND ADVISORY CRITERION. GUSTS MAY DIURNALLY DIMINISH SLIGHTLY...BUT REMAIN HIGH ENOUGH TO PRECLUDE ANY FOG FORMATION TONIGHT. TEMPERATURES AHEAD OF THE FRONT CONTINUE TO BE ABOVE NORMAL...WITH READINGS NEAR 80F ACROSS MOST OF SOUTH FLORIDA. MODELS HAVE TRENDED A BIT SLOWER FOR FROPA FOR SOUTH FLORIDA. THE SFC FRONT LOCATED NEAR KPNS NOW WILL TREK ACROSS THE PANHANDLE THIS EVENING...THEN APPROACH I-4 CORRIDOR OVERNIGHT. IT IS NOT EXPECTED TO INTRUDE ON NORTHWEST SECTIONS OF OUR CWA UNTIL AROUND SUNRISE. THUS...WARM AND FAIRLY BREEZY NIGHT IS IN STORE. MINIMA WILL RANGE FROM AROUND 60F NORTHWEST INTERIOR TO AROUND 70F ATLANTIC METROS. THE COLD FRONT WILL MOVE ACROSS SOUTH FLORIDA DURING THE MORNING...ACCOMPANIED BY A FEW SHOWERS. DYNAMICAL FORCING WILL BE NEGLIGIBLE AND ATMOSPHERE WILL REMAIN FAIRLY STABLE...BUT LOW-LEVEL CONVERGENCE AND DECENT MOISTURE CONTENT SHOULD BE SUFFICIENT FOR SCATTERED ACTIVITY ALONG AND IN VICINITY OF SURFACE BOUNDARY. CAA WILL LAG SEVERAL HOURS BEHIND THE FRONT...SO HIGH TEMPERATURES WILL STILL REACH M/U70S MOST LOCATIONS. SKIES CLEAR AND TEMPERATURES PLUMMET THURSDAY NIGHT...AND DESPITE LACK OF IDEAL RADIATIONAL COOLING CONDITIONS...ADVECTION SHOULD SUPPORT MINIMA REACHING BELOW 50F FOR MUCH OF THE INTERIOR...AND SOME 30S ARE POSSIBLE ACROSS COLLIER...GLADES...AND HENDRY COUNTY. IT APPEARS DRY LOW LEVELS AND NON-ZERO WIND SPEEDS WILL PREVENT ANY FROST...BUT THIS WILL BE MONITORED. AFOREMENTIONED WINDS HOWEVER WILL CREATE WIND CHILL VALUES SOME 5-10 DEGREES LOWER THAN AMBIENT READINGS...LOW ENOUGH TO POSSIBLY REACH ADVISORY THRESHOLDS ACROSS MAINLY GLADES AND HENDRY COUNTIES. TEMPERATURES FRIDAY AND FRIDAY NIGHT WILL BE SLIGHTLY BELOW NORMAL...WITH L70S FOR MAXIMA AND 40S INLAND/50S COASTAL FOR MINIMA. HIGH PRESSURE BUILDING SOUTH WILL KEEP SKIES CLEAR...AND NORTH WINDS WILL GRADUALLY BECOME NORTHEAST AND BECOME QUITE LIGHT OVERNIGHT FRIDAY. TEMPERATURES ATTM APPEAR JUST ABOVE VALUES THAT WOULD CAUSE FROST CONCERN AND LACK OF WIND SHOULD PRECLUDE ANY WIND CHILL CONCERNS. LONG TERM /SATURDAY THROUGH WEDNESDAY/... THE EXTENDED PERIOD FROM THIS WEEKEND INTO THE MIDDLE OF NEXT WEEK LOOKS UNEVENTFUL AND DRY AS SEVERAL MID LEVEL TROUGHS MOVE ACROSS THE NORTHERN STATES MAINTAINING A WEST TO NORTHWEST FLOW OF DRY AIR OVER THE FLORIDA PENINSULA AND KEEPING THE MID LEVEL RIDGE SUPPRESSED TO OUR SOUTHEAST. AS THE TROUGHS MOVE TO OUR NORTH, THIS WILL ALSO REINFORCE THE SURFACE RIDGING ACROSS THE SOUTHEAST STATES WHICH IN TURN WILL KEEP THE TEMPERATURES CLOSE TO OR SLIGHTLY BELOW CLIMATOLOGICAL AVERAGES FOR THE BEGINNING OF FEBRUARY. AVIATION... GUSTY SOUTHEASTERLY WINDS WILL CONTINUE THROUGH THE TAF PERIOD AT ALL SITES. FROPA IS STILL EXPECTED ACROSS THE EAST COAST TERMINALS BETWEEN 10Z-13Z ACCOMPANIED BY SCATTERED SHOWERS. BRIEF PERIODS OF MVFR CIGS WILL LIKELY ACCOMPANY ANY SHOWER ACTIVITY BUT SHOULD NOT BE LONG ENOUGH TO PREVAIL IN THE TAF. WINDS WILL TURN AROUND TO THE NORTHWEST BEHIND THE FRONT AND REMAIN AT AROUND 10 KNOTS. MARINE... WINDS NEAR 20 KTS WITH SOUTHERLY GUSTS TO NEAR 30 KTS WARRANTED ISSUANCE OF SMALL CRAFT ADVISORY EARLY TODAY...AND THIS WILL REMAIN IN EFFECT FOR ALL MARINE ZONES OVERNIGHT. STRONG WINDS BEING INDUCED BY TIGHT PRESSURE GRADIENT IN ADVANCE OF QUICK- MOVING COLD FRONT. THIS FRONT WILL PASS THROUGH EARLY FRIDAY...WITH NORTH WINDS LIKELY EXCEEDING ADVISORY THRESHOLD BEHIND IT. STRONG WINDS AND BUILDING SEAS WILL IMPACT THE WATERS THURSDAY NIGHT THROUGH AT LEAST FRIDAY...BEFORE SUBSIDING AS HIGH PRESSURE BUILDS OVERHEAD. FIRE WEATHER... NO FIRE WEATHER CONCERNS TODAY. A COLD FRONT WILL RACE THROUGH SOUTH FLORIDA THURSDAY MORNING...WITH MUCH DRIER AIR MOVING IN IN ITS WAKE. RELATIVE HUMIDITY VALUES MAY DROP TO NEAR 35 PERCENT THURSDAY AFTERNOON ACROSS GLADES AND HENDRY COUNTIES AND NORTH WINDS WILL BE 10 TO 15 MPH OR HIGHER. FORECAST CONDITIONS DONT SUPPORT ISSUANCE OF FIRE WEATHER WATCH...BUT A FIRE DANGER STATEMENT HAS BEEN ISSUED THURSDAY. RELATIVE HUMIDITY WILL BE VERY LOW FRIDAY...BUT WINDS WILL SUBSIDE A BIT. STILL...FIRE WEATHER HEADLINES ARE LIKELY ON FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 67 75 52 71 / 20 30 - 0 FORT LAUDERDALE 71 79 56 72 / 20 30 - 0 MIAMI 71 80 57 72 / 20 20 - 0 NAPLES 66 71 46 71 / 30 20 - 0 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR BISCAYNE BAY- COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM- GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...57/DG
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
627 AM EST TUE JAN 29 2013 ...WIDESPREAD DENSE FOG THIS MORNING... .SYNOPSIS... ATLANTIC HIGH PRESSURE WILL PREVAIL TONIGHT INTO WEDNESDAY. A STRONG COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY...BRINGING WINDY CONDITIONS AND THE THREAT OF THUNDERSTORMS. AFTER THE COLD FRONT PUSHES OFFSHORE WEDNESDAY NIGHT...HIGH PRESSURE WILL SUPPORT COOLER AND DRIER CONDITIONS INTO NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DENSE FOG ADVISORY ALL ZONES UNTIL 10 AM. HIGH RESOLUTION DATA SUGGESTS FOG MAY LINGER WELL INTO THE MORNING OVER MUCH OF INTERIOR SOUTHEAST SOUTH CAROLINA WHICH MAY HAVE AN IMPACT ON HIGH TEMPERATURES. LATEST RAP SUGGESTS TEMPERATURES WILL NOT PEAK MUCH OUT OF THE MID 60S. NOT READY TO MAKE ANY CHANGES AT THIS POINT...BUT IT IS A CONCERNING TREND. ALSO...NEW GUIDANCE SUGGESTS SEA FOG OFFSHORE MAY MOVE INLAND LATE THIS AFTERNOON AND SPREAD INLAND THIS EVENING. THIS IS NOT SPECIFICALLY ADDRESSED IN THE FORECAST...BUT AGAIN...THIS TREND WILL HAVE TO BE MONITORED. TODAY...THE WESTERN PERIPHERY OF ATLANTIC HIGH PRESSURE WILL EXTEND ACROSS THE SOUTHEAST U.S. TODAY AS A POTENT STORM SYSTEM MATURES ACROSS THE CENTRAL PLAINS. BROAD WARM AIR ADVECTION AHEAD OF THIS SYSTEM WILL PUSH H8 TEMPERATURES TO +12-13C WHICH COUPLED WITH SOME INSOLATION WILL ALLOW HIGHS TO SOAR IN THE MID- UPPER 70S AWAY FROM THE COAST. AN ONSHORE FLOW OVER THE COLDER SHELF WATERS WILL TEMPER THERMAL RISES A BIT ROUGHLY EAST OF HIGHWAY 17 IN SOUTH CAROLINA AND I-95 IN SOUTHEAST GEORGIA WITH THE BEACHES LIKELY NOT WARMING OUT OF THE UPPER 50S/LOWER 60S. LOOKS LIKE THE HIGHS AT BOTH THE SAVANNAH AND CHARLESTON AIRPORTS WILL REMAIN BELOW RECORD TERRITORY--84 SET IN 1957 AT SAVANNAH AND 79 SET IN 2002 AND 1947 AT CHARLESTON. THE DAY WILL START OUT CLOUDY DUE TO WIDESPREAD FOG AND STRATUS WHICH WILL DISSIPATE BY MID-MORNING YIELDING AT LEAST PARTLY CLOUDY SKIES. CLOUDS WILL THEN BEGIN TO INCREASE LATER THIS AFTERNOON AS ISENTROPIC ASSENT/WARM AIR ADVECTION STRENGTHENS IN RESPONSE TO AN INTENSIFYING LOW-LEVEL JET. THE CORE OF THE STRONGEST LIFT LOOKS TO REMAIN DISPLACED WELL TO THE WEST...SO IT APPEARS THE NAM/S DEPICTION OF ISOLATED TO SCATTERED SHOWERS FORMING INLAND IS LIKELY TOO AGGRESSIVE PER THE LATEST RAP/H3R RUNS. WILL KEEP THE FORECAST RAIN FREE FOR NOW WITH GRIDDED POPS GENERALLY LESS THAN 10 PERCENT. THERE IS A POSSIBILITY THAT SOME SEA FOG WILL FORM OVER THE COOL NEARSHORE WATERS THIS AFTERNOON AS DEWPOINTS RISE INTO THE LOWER- MID 60S. AS SOUTHERLY WINDS INCREASE...THERE IS A POSSIBILITY THAT SOME OF THIS COULD PUSH INLAND AND AFFECT SOME BEACH COMMUNITIES. THIS IS CERTAINLY SOMETHING THAT WILL HAVE TO BE WATCHED VERY CAREFULLY. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... TONIGHT...IT WILL BE A RELATIVELY WARM NIGHT FOR LATE JANUARY WITH THE REGION PLACED SOLIDLY WITHIN THE WARM SECTOR OF THE APPROACHING FRONTAL SYSTEM. A STRENGTHENING LOW-LEVEL JET WILL KEEP THE ATMOSPHERE WELL MIXED WITH THE BOUNDARY LAYER REMAINING DECOUPLED. LOWS WILL ONLY BOTTOM OUT IN THE LOWER 60S FOR MOST LOCALES. IT APPEARS THE BEST RAIN CHANCES WILL REMAIN WELL TO THE WEST CLOSER TO THE FRONT ITSELF...BUT WOULD NOT BE SURPRISED TO SEE SOME VERY LIGHT SHOWER ACTIVITY DEVELOP OVER THE FAR NORTHERN ZONES EARLY WEDNESDAY IN THE STRONG WARM AIR ADVECTION REGIME. WILL KEEP THE FORECAST DRY FOR NOW...ALTHOUGH THE INTRODUCTION OF AT LEAST ISOLATED SHOWERS MAY BE NEEDED IN LATER FORECAST CYCLES. WEDNESDAY...THE AXIS OF A ROBUST UPPER TROUGH WILL SWEEP FROM THE GREAT PLAINS INTO THE OHIO/TENNESSEE VALLEY THROUGH THE DAY...PROVIDING THE ENERGY TO PUSH A STRONG COLD FRONT INTO THE FORECAST AREA BY THE LATE AFTERNOON/EARLY EVENING HOURS. IMPRESSIVE DYNAMICS WILL BE ENHANCING A LINE OF CONVECTION MOVING EASTWARD WITH THE COLD FRONT...WHILE LATEST NUMERICAL MODEL SOLUTIONS DELAY THE INTRUSION OF THESE SHOWERS/THUNDERSTORMS UNTIL AT LEAST 21Z TO 00Z. WARM ADVECTION COULD STILL INITIATE SOME ISOLATED TO SCATTERED SHOWER ACTIVITY AHEAD OF THE FRONT...AND HAVE THUS INTRODUCED 20 TO 30 PERCENT RAIN CHANCES AS EARLY AS MID MORNING. RAIN COVERAGE AND INTENSITY WILL THEN GRADUALLY INCREASE FROM WEST TO EAST AS THE FRONT APPROACHES THE REGION...PEAKING IN THE EVENING/NIGHTTIME PERIOD. THE MAIN QUESTION THEN BECOMES THE POTENTIAL FOR SEVERE WEATHER LATE WEDNESDAY. STORM PREDICTION CENTER HAS MAINTAINED A SLIGHT RISK FOR SEVERE WEATHER ACROSS THE FORECAST AREA ON WEDNESDAY. DYNAMICS ASSOCIATED WITH THE APPROACHING FRONTAL SYSTEM ARE CONCERNING...AS A 50 TO 60 KT LOW LEVEL JET MOVES DIRECTLY OVER THE AREA BY THE EVENING HOURS. THE AXIS OF THE UPPER JET WILL BE DELAYED TO THE WEST...HOWEVER THE FORECAST AREA WILL STILL BECOME LOCATED UNDER 110 TO 120 KT FLOW ALOFT ALONG THE EASTERN PERIPHERY OF THE JET. SHEAR PROFILES WILL THUS BE QUITE STRONG...AND WHEN COMBINED WITH A TIGHTENED PRESSURE GRADIENT AHEAD OF THE COLD FRONT...PREVAILING WINDS ACROSS THE FORECAST AREA WILL BE GUSTY EVEN BEFORE STRONGEST PRECIPITATION ARRIVES. AS TEMPERATURES WARM WELL ABOVE NORMAL INTO THE UPPER 70S TO NEAR 80 DEGREES...MIXING DURING THE PEAK HEATING HOURS COULD TAP INTO THE IMPRESSIVE BOUNDARY LAYER WINDS AND SUPPORT WIND ADVISORY CONDITIONS. HOWEVER...AS THE CONVECTIVE PRECIPITATION ASSOCIATED WITH THE COLD FRONT APPROACHES...INSTABILITY AND LAPSE RATES STILL APPEAR MARGINAL AT BEST. THIS LENDS SOME UNCERTAINTY TO THE POTENTIAL FOR STORMS TO BECOME SEVERE AND PRODUCE DAMAGING WINDS GUSTS. DUE TO THE STRONG DYNAMICS FOR FORCING...WILL MAINTAIN MENTION OF A SLIGHT CHANCE FOR THUNDER...YET REMAIN SOMEWHAT CONSERVATIVE DUE TO THE INHERENT ISSUES OF HIGH SHEAR/LOW INSTABILITY ENVIRONMENTS. WILL MAINTAIN MENTION OF SEVERE POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK TO ADDRESS THE POSSIBILITY OF AT LEAST ISOLATED SEVERE THUNDERSTORM DEVELOPMENT. WEDNESDAY NIGHT AND THURSDAY...THE UPPER TROUGH WILL LIFT AND FLATTEN BY WEDNESDAY NIGHT...WITH THE COLD FRONT RAPIDLY MOVING OFFSHORE BY DAYBREAK THURSDAY. PRECIPITATION POTENTIAL PEAKING BEFORE MIDNIGHT WILL QUICKLY DECREASE FROM WEST TO EAST DURING THE PRE DAWN HOURS...WITH RAIN CHANCES BELOW 15 PERCENT BY SUNRISE. DRY HIGH PRESSURE WILL BUILD BEHIND THE DEPARTING SYSTEM...AND STRONG COLD ADVECTION WILL SUPPORT HIGH TEMPERATURES THURSDAY AFTERNOON 15 TO 20 DEGREES COOLER THAN THE PREVIOUS DAY. HIGHS WILL BE SUPPRESSED AROUND 60 DEGREES DESPITE SCATTERING SKY COVER AND BETTER INSOLATION. CONTINUING COLD ADVECTION AND TIGHTENED PRESSURE GRADIENTS WILL SUPPORT ANOTHER BREEZY AFTERNOON...ESPECIALLY AS BETTER MIXING UNDER CLEARING SKIES TAPS INTO BOUNDARY LAYER FLOW. LOW TEMPERATURES THURSDAY NIGHT WILL ALSO REFLECT THE SIGNIFICANT CHANCE IN AIR MASS...WITH TEMPERATURES FALLING INTO THE LOW 30S INLAND TO THE MID/UPPER 30S CLOSER TO THE COAST. FRIDAY...HIGH PRESSURE WILL BE REINFORCED FROM THE NORTH...AND WITH NEARLY ZONAL FLOW ALOFT...EXPECT ANOTHER DRY AND COOL DAY. TEMPERATURES WILL RANGE RIGHT AROUND SEASONAL NORMALS FOR EARLY FEBRUARY...PEAKING AROUND 60 DEGREES UNDER MOSTLY SUNNY SKIES. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... AN UPPER LEVEL SHORTWAVE WILL AMPLIFY AS IT SLIPS SOUTHEAST INTO THE REGION ON SATURDAY...ALLOWING A WEAK WAVE OF LOW PRESSURE AND COLD FRONT TO MOVE ACROSS THE MID ATLANTIC AND SOUTHEAST STATES. DEEP MOISTURE AND DYNAMICS WILL BE MUCH MORE LIMITED WITH THIS SYSTEM...AND HAVE THUS MAINTAINED A DRY FORECAST. HIGH PRESSURE WILL QUICKLY REBUILD BEHIND THE DEPARTING SHORTWAVE AND FRONT...STEADILY MOVING INTO THE ATLANTIC EARLY NEXT WEEK. A STRONGER COLD FRONT COULD APPROACH THE FORECAST AREA BY TUESDAY...HOWEVER WILL KEEP POPS BELOW 15 PERCENT DUE TO TIMING AND IMPACT UNCERTAINTIES THIS FAR IN ADVANCE. HIGH TEMPERATURES WILL GENERALLY REACH THE LOW 60S EACH AFTERNOON...WITH LOWS MODERATING INTO THE UPPER 30S TO LOWER 40S. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... BIGGEST CONCERN IS TRYING TO TIME WHEN THE FOG WILL LIFT ABOVE VARIOUS AIRPORT MINIMUMS. LOOKS LIKE LIFR VSBYS WILL LINGER THROUGH ABOUT 14Z WITH SOME IMPROVEMENT BETWEEN 14-16Z. ITS UNCLEAR WHETHER IFR OR MVFR CIGS WILL ESTABLISH THEMSELVES AS THE FOG LAYER LIFTS...BUT WILL HIGHLIGHT SOME CIGS TO COVER. EXPECT VFR TO RETURN BY 16-17Z AT BOTH TERMINALS. BIG QUESTION LATE THIS AFTERNOON AND OVERNIGHT IS WHETHER SEA FOG WILL MOVE INLAND AND IMPACT THE TERMINALS BY EARLY EVENING. GUIDANCE IS ALL OVER THE PLACE ON THIS POTENTIAL SO LIMITED CONDITIONS TO MVFR FOR NOW. COULD SEE MARGINAL LOW-LEVEL WIND SHEAR EARLY WEDNESDAY...BUT WILL NOT INTRODUCE JUST YET AS IT LOOK MARGINAL. EXTENDED AVIATION OUTLOOK...WINDY CONDITIONS EXPECTED ON WEDNESDAY...WITH LOW-LEVEL WIND SHEAR POSSIBLE WEDNESDAY MORNING BEFORE MIXING INCREASES LATE MORNING. TEMPO MVFR OR LOWER CIGS/ VSBYS ARE POSSIBLE WEDNESDAY EVENING/NIGHT WITH SHOWERS AND/OR THUNDERSTORMS ALONG A COLD FRONT. EXPECT PREVAILING VFR CONDITIONS TO RETURN BY THURSDAY INTO THE LATE WEEK PERIOD. && .MARINE... TODAY...MARINE DENSE FOG ADVISORY FOR THE CHARLESTON HARBOR UNTIL 10 AM AND ALL NEARSHORE LEGS UNTIL 1 PM. WEBCAMS SUGGEST VERY DENSE FOG HAS DEVELOPED OFFSHORE. THE FOG WILL LIKELY LINGER WELL INTO THE DAY AS THE FOG WILL REMAIN TRAPPED WITHIN THE STRONG MARINE LAYER. LIGHT WINDS WILL BECOME SOUTHERLY AND INCREASE TO 5-10 KT TODAY AHEAD OF AN APPROACHING COLD FRONT. INCREASING DEWPOINTS OVER THE CHILLY SHELF WATERS COULD SUPPORT AT LEAST PATCHY SEA FOG OVER THE NEARSHORE WATERS TODAY. IT REMAINS TO BE SEEN HOW WIDESPREAD ANY SEA FOG COULD BECOME...BUT A MARINE DENSE FOG ADVISORIES MAY BE NEEDED AT SOME POINT. SEAS WILL RANGE FROM 2-4 FT...HIGHEST OFFSHORE WATERS. TONIGHT...WINDS WILL BEGIN TO INCREASE AS LOW-LEVEL JETTING INTENSIFIES AHEAD OF THE APPROACHING COLD FRONT. WINDS LOOK TO MAX OUT AT 15-20 KT ALL WATERS AND LOCAL SWAN OUTPUT SUGGESTS SEAS WILL REMAIN BELOW 6 FT...SO WILL NOT HOIST A SMALL CRAFT ADVISORY FOR ANY MARINE LEGS FOR THE TONIGHT PERIOD. ANY SEA FOG COULD LINGER IN THE NEARSHORE WATERS FOR MUCH OF THE NIGHT. WEDNESDAY THROUGH SATURDAY...MARINE CONDITIONS WILL RAPIDLY DETERIORATE ON WEDNESDAY...AS THE PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY AHEAD OF A COLD FRONT AND AN IMPRESSIVE 50 TO 60 KT LOW LEVEL JET MOVES OVER THE AREA. DUE TO DECENT CONFIDENCE IN SECOND AND THIRD PERIOD WIND POTENTIAL...HAVE ISSUED SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS AND THE CHARLESTON HARBOR BEGINNING 15Z WEDNESDAY. HAVE ALSO RAISED A GALE WATCH FOR THE OFFSHORE GEORGIA WATERS AT 15Z...WHEN FREQUENT GUSTS ABOVE 34 KT ARE MOST LIKELY TO INITIATE. GALE CONDITIONS COULD ALSO OCCUR ACROSS THE NEARSHORE WATERS...ESPECIALLY THE MARINE ZONES ADJACENT TO CHARLESTON COUNTY...HOWEVER TIMING SUGGESTS THESE CONDITIONS ARE MORE LIKELY TO BE DELAYED TOWARD WEDNESDAY EVENING OR NIGHT. WILL THUS HOLD OFF ON A GALE WARNING FOR THE NEARSHORE ZONES AT THIS TIME. SEAS WILL BUILD AHEAD OF THE FRONT...PEAKING BETWEEN 5-10 FT BEYOND 10 NM FROM THE COAST. ALTHOUGH THE FRONT WILL RAPIDLY SHIFT OUT OF THE AREA BY THURSDAY MORNING...OFFSHORE WINDS WILL STILL BE QUITE STRONG IN A LOW LEVEL COLD ADVECTION PATTERN...AND SMALL CRAFT ADVISORY CONDITIONS COULD LINGER THROUGH AT LEAST THURSDAY AFTERNOON. WINDS AND SEAS WILL THEN STEADILY DIMINISH THURSDAY NIGHT...REMAINING BELOW ADVISORY CRITERIA FOR THE REMAINDER OF THE FORECAST PERIOD WITH HIGH PRESSURE GENERALLY IN CONTROL. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ087-088- 099>101-114>119-137>141. SC...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ040- 042>045-047>052. MARINE...DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ350- 352-354. SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 7 PM EST THURSDAY FOR AMZ330-350-352-354. GALE WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY MORNING FOR AMZ374. DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ330. && $$ ST/79
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
622 AM EST TUE JAN 29 2013 .SYNOPSIS... ATLANTIC HIGH PRESSURE WILL PREVAIL TONIGHT INTO WEDNESDAY. A STRONG COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY...BRINGING WINDY CONDITIONS AND THE THREAT OF THUNDERSTORMS. AFTER THE COLD FRONT PUSHES OFFSHORE WEDNESDAY NIGHT...HIGH PRESSURE WILL SUPPORT COOLER AND DRIER CONDITIONS INTO NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DENSE FOG ADVISORY ALL ZONES UNTIL 10 AM. HIGH RESOLUTION DATA SUGGESTS FOG MAY LINGER WELL INTO THE MORNING OVER MUCH OF INTERIOR SOUTHEAST SOUTH CAROLINA WHICH MAY HAVE AN IMPACT ON HIGH TEMPERATURES. LATEST RAP SUGGESTS TEMPERATURES WILL NOT PEAK MUCH OUT OF THE MID 60S. NOT READY TO MAKE ANY CHANGES AT THIS POINT...BUT IT IS A CONCERNING TREND. ALSO...NEW GUIDANCE SUGGESTS SEA FOG OFFSHORE MAY MOVE INLAND LATE THIS AFTERNOON AND SPREAD INLAND THIS EVENING. THIS IS NOT SPECIFICALLY ADDRESSED IN THE FORECAST...BUT AGAIN...THIS TREND WILL HAVE TO BE MONITORED. TODAY...THE WESTERN PERIPHERY OF ATLANTIC HIGH PRESSURE WILL EXTEND ACROSS THE SOUTHEAST U.S. TODAY AS A POTENT STORM SYSTEM MATURES ACROSS THE CENTRAL PLAINS. BROAD WARM AIR ADVECTION AHEAD OF THIS SYSTEM WILL PUSH H8 TEMPERATURES TO +12-13C WHICH COUPLED WITH SOME INSOLATION WILL ALLOW HIGHS TO SOAR IN THE MID- UPPER 70S AWAY FROM THE COAST. AN ONSHORE FLOW OVER THE COLDER SHELF WATERS WILL TEMPER THERMAL RISES A BIT ROUGHLY EAST OF HIGHWAY 17 IN SOUTH CAROLINA AND I-95 IN SOUTHEAST GEORGIA WITH THE BEACHES LIKELY NOT WARMING OUT OF THE UPPER 50S/LOWER 60S. LOOKS LIKE THE HIGHS AT BOTH THE SAVANNAH AND CHARLESTON AIRPORTS WILL REMAIN BELOW RECORD TERRITORY--84 SET IN 1957 AT SAVANNAH AND 79 SET IN 2002 AND 1947 AT CHARLESTON. THE DAY WILL START OUT CLOUDY DUE TO WIDESPREAD FOG AND STRATUS WHICH WILL DISSIPATE BY MID-MORNING YIELDING AT LEAST PARTLY CLOUDY SKIES. CLOUDS WILL THEN BEGIN TO INCREASE LATER THIS AFTERNOON AS ISENTROPIC ASSENT/WARM AIR ADVECTION STRENGTHENS IN RESPONSE TO AN INTENSIFYING LOW-LEVEL JET. THE CORE OF THE STRONGEST LIFT LOOKS TO REMAIN DISPLACED WELL TO THE WEST...SO IT APPEARS THE NAM/S DEPICTION OF ISOLATED TO SCATTERED SHOWERS FORMING INLAND IS LIKELY TOO AGGRESSIVE PER THE LATEST RAP/H3R RUNS. WILL KEEP THE FORECAST RAIN FREE FOR NOW WITH GRIDDED POPS GENERALLY LESS THAN 10 PERCENT. THERE IS A POSSIBILITY THAT SOME SEA FOG WILL FORM OVER THE COOL NEARSHORE WATERS THIS AFTERNOON AS DEWPOINTS RISE INTO THE LOWER- MID 60S. AS SOUTHERLY WINDS INCREASE...THERE IS A POSSIBILITY THAT SOME OF THIS COULD PUSH INLAND AND AFFECT SOME BEACH COMMUNITIES. THIS IS CERTAINLY SOMETHING THAT WILL HAVE TO BE WATCHED VERY CAREFULLY. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... TONIGHT...IT WILL BE A RELATIVELY WARM NIGHT FOR LATE JANUARY WITH THE REGION PLACED SOLIDLY WITHIN THE WARM SECTOR OF THE APPROACHING FRONTAL SYSTEM. A STRENGTHENING LOW-LEVEL JET WILL KEEP THE ATMOSPHERE WELL MIXED WITH THE BOUNDARY LAYER REMAINING DECOUPLED. LOWS WILL ONLY BOTTOM OUT IN THE LOWER 60S FOR MOST LOCALES. IT APPEARS THE BEST RAIN CHANCES WILL REMAIN WELL TO THE WEST CLOSER TO THE FRONT ITSELF...BUT WOULD NOT BE SURPRISED TO SEE SOME VERY LIGHT SHOWER ACTIVITY DEVELOP OVER THE FAR NORTHERN ZONES EARLY WEDNESDAY IN THE STRONG WARM AIR ADVECTION REGIME. WILL KEEP THE FORECAST DRY FOR NOW...ALTHOUGH THE INTRODUCTION OF AT LEAST ISOLATED SHOWERS MAY BE NEEDED IN LATER FORECAST CYCLES. WEDNESDAY...THE AXIS OF A ROBUST UPPER TROUGH WILL SWEEP FROM THE GREAT PLAINS INTO THE OHIO/TENNESSEE VALLEY THROUGH THE DAY...PROVIDING THE ENERGY TO PUSH A STRONG COLD FRONT INTO THE FORECAST AREA BY THE LATE AFTERNOON/EARLY EVENING HOURS. IMPRESSIVE DYNAMICS WILL BE ENHANCING A LINE OF CONVECTION MOVING EASTWARD WITH THE COLD FRONT...WHILE LATEST NUMERICAL MODEL SOLUTIONS DELAY THE INTRUSION OF THESE SHOWERS/THUNDERSTORMS UNTIL AT LEAST 21Z TO 00Z. WARM ADVECTION COULD STILL INITIATE SOME ISOLATED TO SCATTERED SHOWER ACTIVITY AHEAD OF THE FRONT...AND HAVE THUS INTRODUCED 20 TO 30 PERCENT RAIN CHANCES AS EARLY AS MID MORNING. RAIN COVERAGE AND INTENSITY WILL THEN GRADUALLY INCREASE FROM WEST TO EAST AS THE FRONT APPROACHES THE REGION...PEAKING IN THE EVENING/NIGHTTIME PERIOD. THE MAIN QUESTION THEN BECOMES THE POTENTIAL FOR SEVERE WEATHER LATE WEDNESDAY. STORM PREDICTION CENTER HAS MAINTAINED A SLIGHT RISK FOR SEVERE WEATHER ACROSS THE FORECAST AREA ON WEDNESDAY. DYNAMICS ASSOCIATED WITH THE APPROACHING FRONTAL SYSTEM ARE CONCERNING...AS A 50 TO 60 KT LOW LEVEL JET MOVES DIRECTLY OVER THE AREA BY THE EVENING HOURS. THE AXIS OF THE UPPER JET WILL BE DELAYED TO THE WEST...HOWEVER THE FORECAST AREA WILL STILL BECOME LOCATED UNDER 110 TO 120 KT FLOW ALOFT ALONG THE EASTERN PERIPHERY OF THE JET. SHEAR PROFILES WILL THUS BE QUITE STRONG...AND WHEN COMBINED WITH A TIGHTENED PRESSURE GRADIENT AHEAD OF THE COLD FRONT...PREVAILING WINDS ACROSS THE FORECAST AREA WILL BE GUSTY EVEN BEFORE STRONGEST PRECIPITATION ARRIVES. AS TEMPERATURES WARM WELL ABOVE NORMAL INTO THE UPPER 70S TO NEAR 80 DEGREES...MIXING DURING THE PEAK HEATING HOURS COULD TAP INTO THE IMPRESSIVE BOUNDARY LAYER WINDS AND SUPPORT WIND ADVISORY CONDITIONS. HOWEVER...AS THE CONVECTIVE PRECIPITATION ASSOCIATED WITH THE COLD FRONT APPROACHES...INSTABILITY AND LAPSE RATES STILL APPEAR MARGINAL AT BEST. THIS LENDS SOME UNCERTAINTY TO THE POTENTIAL FOR STORMS TO BECOME SEVERE AND PRODUCE DAMAGING WINDS GUSTS. DUE TO THE STRONG DYNAMICS FOR FORCING...WILL MAINTAIN MENTION OF A SLIGHT CHANCE FOR THUNDER...YET REMAIN SOMEWHAT CONSERVATIVE DUE TO THE INHERENT ISSUES OF HIGH SHEAR/LOW INSTABILITY ENVIRONMENTS. WILL MAINTAIN MENTION OF SEVERE POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK TO ADDRESS THE POSSIBILITY OF AT LEAST ISOLATED SEVERE THUNDERSTORM DEVELOPMENT. WEDNESDAY NIGHT AND THURSDAY...THE UPPER TROUGH WILL LIFT AND FLATTEN BY WEDNESDAY NIGHT...WITH THE COLD FRONT RAPIDLY MOVING OFFSHORE BY DAYBREAK THURSDAY. PRECIPITATION POTENTIAL PEAKING BEFORE MIDNIGHT WILL QUICKLY DECREASE FROM WEST TO EAST DURING THE PRE DAWN HOURS...WITH RAIN CHANCES BELOW 15 PERCENT BY SUNRISE. DRY HIGH PRESSURE WILL BUILD BEHIND THE DEPARTING SYSTEM...AND STRONG COLD ADVECTION WILL SUPPORT HIGH TEMPERATURES THURSDAY AFTERNOON 15 TO 20 DEGREES COOLER THAN THE PREVIOUS DAY. HIGHS WILL BE SUPPRESSED AROUND 60 DEGREES DESPITE SCATTERING SKY COVER AND BETTER INSOLATION. CONTINUING COLD ADVECTION AND TIGHTENED PRESSURE GRADIENTS WILL SUPPORT ANOTHER BREEZY AFTERNOON...ESPECIALLY AS BETTER MIXING UNDER CLEARING SKIES TAPS INTO BOUNDARY LAYER FLOW. LOW TEMPERATURES THURSDAY NIGHT WILL ALSO REFLECT THE SIGNIFICANT CHANCE IN AIR MASS...WITH TEMPERATURES FALLING INTO THE LOW 30S INLAND TO THE MID/UPPER 30S CLOSER TO THE COAST. FRIDAY...HIGH PRESSURE WILL BE REINFORCED FROM THE NORTH...AND WITH NEARLY ZONAL FLOW ALOFT...EXPECT ANOTHER DRY AND COOL DAY. TEMPERATURES WILL RANGE RIGHT AROUND SEASONAL NORMALS FOR EARLY FEBRUARY...PEAKING AROUND 60 DEGREES UNDER MOSTLY SUNNY SKIES. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... AN UPPER LEVEL SHORTWAVE WILL AMPLIFY AS IT SLIPS SOUTHEAST INTO THE REGION ON SATURDAY...ALLOWING A WEAK WAVE OF LOW PRESSURE AND COLD FRONT TO MOVE ACROSS THE MID ATLANTIC AND SOUTHEAST STATES. DEEP MOISTURE AND DYNAMICS WILL BE MUCH MORE LIMITED WITH THIS SYSTEM...AND HAVE THUS MAINTAINED A DRY FORECAST. HIGH PRESSURE WILL QUICKLY REBUILD BEHIND THE DEPARTING SHORTWAVE AND FRONT...STEADILY MOVING INTO THE ATLANTIC EARLY NEXT WEEK. A STRONGER COLD FRONT COULD APPROACH THE FORECAST AREA BY TUESDAY...HOWEVER WILL KEEP POPS BELOW 15 PERCENT DUE TO TIMING AND IMPACT UNCERTAINTIES THIS FAR IN ADVANCE. HIGH TEMPERATURES WILL GENERALLY REACH THE LOW 60S EACH AFTERNOON...WITH LOWS MODERATING INTO THE UPPER 30S TO LOWER 40S. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/... FOG IS ALREADY BEGINNING TO FORM AT BOTH TERMINALS EARLY THIS MORNING. THE FOG IS PRETTY SHALLOW SO FAR WHICH WILL LIKELY RESULT IN VSBYS BOUNCING FOR A FEW MORE HOURS BEFORE SETTLING DOWN AFTER 09Z ONCE THE FOG LAYERS THICKEN. ANTICIPATE LIFR CONDITIONS TO IMPACT THE TERMINALS WITH BOTH CIGS AND VSBYS REACHING AIRPORT MINIMUMS. THERE IS SOME HINT THAT A MID-LEVEL CLOUD DECK AROUND 5000 FT COULD DEVELOP JUST AS THE FOG POTENTIAL PEAKS. IT IS UNCLEAR WHETHER THIS LAYER WILL FORM...BUT IF IT DOES CONDITIONS COULD STAY ABOVE AIRFIELD AND POSSIBLY ALTERNATE MINIMUMS. FOR NOW...WILL SHOW PREVAILING LIFR CONDITIONS AT BOTH TERMINALS BY 09Z AND MAINTAIN THIS UNTIL 14-15Z AFTER WHICH CONDITIONS WILL IMPROVE TO VFR AS THE FOG LAYER DISSIPATES. EXTENDED AVIATION OUTLOOK...WINDY CONDITIONS EXPECTED ON WEDNESDAY...WITH LOW-LEVEL WIND SHEAR POSSIBLE WEDNESDAY MORNING BEFORE MIXING INCREASES LATE MORNING. TEMPO MVFR OR LOWER CIGS/ VSBYS ARE POSSIBLE WEDNESDAY EVENING/NIGHT WITH SHOWERS AND/OR THUNDERSTORMS ALONG A COLD FRONT. EXPECT PREVAILING VFR CONDITIONS TO RETURN BY THURSDAY INTO THE LATE WEEK PERIOD. && .MARINE... TODAY...MARINE DENSE FOG ADVISORY FOR THE CHARLESTON HARBOR UNTIL 10 AM AND ALL NEARSHORE LEGS UNTIL 1 PM. WEBCAMS SUGGEST VERY DENSE FOG HAS DEVELOPED OFFSHORE. THE FOG WILL LIKELY LINGER WELL INTO THE DAY AS THE FOG WILL REMAIN TRAPPED WITHIN THE STRONG MARINE LAYER. LIGHT WINDS WILL BECOME SOUTHERLY AND INCREASE TO 5-10 KT TODAY AHEAD OF AN APPROACHING COLD FRONT. INCREASING DEWPOINTS OVER THE CHILLY SHELF WATERS COULD SUPPORT AT LEAST PATCHY SEA FOG OVER THE NEARSHORE WATERS TODAY. IT REMAINS TO BE SEEN HOW WIDESPREAD ANY SEA FOG COULD BECOME...BUT A MARINE DENSE FOG ADVISORIES MAY BE NEEDED AT SOME POINT. SEAS WILL RANGE FROM 2-4 FT...HIGHEST OFFSHORE WATERS. TONIGHT...WINDS WILL BEGIN TO INCREASE AS LOW-LEVEL JETTING INTENSIFIES AHEAD OF THE APPROACHING COLD FRONT. WINDS LOOK TO MAX OUT AT 15-20 KT ALL WATERS AND LOCAL SWAN OUTPUT SUGGESTS SEAS WILL REMAIN BELOW 6 FT...SO WILL NOT HOIST A SMALL CRAFT ADVISORY FOR ANY MARINE LEGS FOR THE TONIGHT PERIOD. ANY SEA FOG COULD LINGER IN THE NEARSHORE WATERS FOR MUCH OF THE NIGHT. WEDNESDAY THROUGH SATURDAY...MARINE CONDITIONS WILL RAPIDLY DETERIORATE ON WEDNESDAY...AS THE PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY AHEAD OF A COLD FRONT AND AN IMPRESSIVE 50 TO 60 KT LOW LEVEL JET MOVES OVER THE AREA. DUE TO DECENT CONFIDENCE IN SECOND AND THIRD PERIOD WIND POTENTIAL...HAVE ISSUED SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS AND THE CHARLESTON HARBOR BEGINNING 15Z WEDNESDAY. HAVE ALSO RAISED A GALE WATCH FOR THE OFFSHORE GEORGIA WATERS AT 15Z...WHEN FREQUENT GUSTS ABOVE 34 KT ARE MOST LIKELY TO INITIATE. GALE CONDITIONS COULD ALSO OCCUR ACROSS THE NEARSHORE WATERS...ESPECIALLY THE MARINE ZONES ADJACENT TO CHARLESTON COUNTY...HOWEVER TIMING SUGGESTS THESE CONDITIONS ARE MORE LIKELY TO BE DELAYED TOWARD WEDNESDAY EVENING OR NIGHT. WILL THUS HOLD OFF ON A GALE WARNING FOR THE NEARSHORE ZONES AT THIS TIME. SEAS WILL BUILD AHEAD OF THE FRONT...PEAKING BETWEEN 5-10 FT BEYOND 10 NM FROM THE COAST. ALTHOUGH THE FRONT WILL RAPIDLY SHIFT OUT OF THE AREA BY THURSDAY MORNING...OFFSHORE WINDS WILL STILL BE QUITE STRONG IN A LOW LEVEL COLD ADVECTION PATTERN...AND SMALL CRAFT ADVISORY CONDITIONS COULD LINGER THROUGH AT LEAST THURSDAY AFTERNOON. WINDS AND SEAS WILL THEN STEADILY DIMINISH THURSDAY NIGHT...REMAINING BELOW ADVISORY CRITERIA FOR THE REMAINDER OF THE FORECAST PERIOD WITH HIGH PRESSURE GENERALLY IN CONTROL. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ087-088- 099>101-114>119-137>141. SC...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ040- 042>045-047>052. MARINE...DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ350- 352-354. SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 7 PM EST THURSDAY FOR AMZ330-350-352-354. GALE WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY MORNING FOR AMZ374. DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ330. && $$ ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
410 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEWPOINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WINDCHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * SCATTERED SHOWERS AND THUNDERSTORMS WILL PERSIST UNTIL AROUND 00Z...THEN A MORE SOLID LINE WILL PASS THROUGH THE TERMINALS WITH A SHORT PERIOD OF PREVAILING RAIN AND THUNDER. AFTER ARND 02Z...WIDESPREAD RAIN WILL PERSIST THROUGH THE EVENING. * SOUTH WINDS GUSTING TO ARND 20 KT...SHIFTINGTO SWLY WITH GUSTS TO 25KT WITH THE MORE SOLID LINE OF SHRA/TSRA. WINDS VEERING WYL AND NWLY THROUGH THE EVENING. AND OVERNIGHT. * MVFR CONDITIONS PREVAILING THE REMAINDER OF THIS AFTERNOON AND INTO THE EVENING...WITH OCNL IFR LIKELY. THEN PREVAILING IFR CIGS THROUGH THE NIGHT. KREIN //DISCUSSION...UPDATED 18Z... A SERIES OF UPPER LEVEL WAVES HAS BEEN MOVING ACROSS THE AREA WITH PERIODS OF SHRA AND TSRA. THE NEXT OF THESE WAVES IS MOVING OUT OF THE SOUTHERN PLAINS AT MID DAY AND IS EXPECTED TO BRING A LARGE AREA OF RA/SHRA WITH EMBEDDED TSRA TO NORTHERN IL AND NORTHWEST IN LATE THIS AFTERNOON AND THROUGH THE EVENING. HAVE HIGHLIGHTED THE MOST LIKELY TIME FRAME IN THE TAFS BUT THE TIMING MAY NEED TO BE ADJUSTED AS DETAILS BECOME MORE CLEAR. CONDITIONS LOWERING TO IFR OVERNIGHT AS A SURFACE COLD FRONT MOVES ACROSS THE AREA AND SHIFTS THE WINDS TO WEST TO NORTHWEST. COLDER AIR BEHIND THE FRONT WILL TURN THE REMAINING PRECIPITATION TO SN ON WEDNESDAY. PAW //ORD AND MDW CONFIDENCE...UPDATED 22Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS EVENING...AND IN CIG/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN IFR TIMING. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 6 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
320 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEWPOINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WINDCHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * AN AREA OF SHOWERS AND THUNDERSTORMS APPROACHING ORD AND MDW FROM THE SOUTHWEST AT 20Z. MORE WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS MOVING IN LATER THIS AFTERNOON AND THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR CONDITIONS PREVAILING THIS AFTERNOON AND EVENING. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 18Z... A SERIES OF UPPER LEVEL WAVES HAS BEEN MOVING ACROSS THE AREA WITH PERIODS OF SHRA AND TSRA. THE NEXT OF THESE WAVES IS MOVING OUT OF THE SOUTHERN PLAINS AT MID DAY AND IS EXPECTED TO BRING A LARGE AREA OF RA/SHRA WITH EMBEDDED TSRA TO NORTHERN IL AND NORTHWEST IN LATE THIS AFTERNOON AND THROUGH THE EVENING. HAVE HIGHLIGHTED THE MOST LIKELY TIME FRAME IN THE TAFS BUT THE TIMING MAY NEED TO BE ADJUSTED AS DETAILS BECOME MORE CLEAR. CONDITIONS LOWERING TO IFR OVERNIGHT AS A SURFACE COLD FRONT MOVES ACROSS THE AREA AND SHIFTS THE WINDS TO WEST TO NORTHWEST. COLDER AIR BEHIND THE FRONT WILL TURN THE REMAINING PRECIPITATION TO SN ON WEDNESDAY. PAW //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN IFR TIMING. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 6 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
245 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * AN AREA OF SHOWERS AND THUNDERSTORMS APPROACHING ORD AND MDW FROM THE SOUTHWEST AT 20Z. MORE WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS MOVING IN LATER THIS AFTERNOON AND THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR CONDITIONS PREVAILING THIS AFTERNOON AND EVENING. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 18Z... A SERIES OF UPPER LEVEL WAVES HAS BEEN MOVING ACROSS THE AREA WITH PERIODS OF SHRA AND TSRA. THE NEXT OF THESE WAVES IS MOVING OUT OF THE SOUTHERN PLAINS AT MID DAY AND IS EXPECTED TO BRING A LARGE AREA OF RA/SHRA WITH EMBEDDED TSRA TO NORTHERN IL AND NORTHWEST IN LATE THIS AFTERNOON AND THROUGH THE EVENING. HAVE HIGHLIGHTED THE MOST LIKELY TIME FRAME IN THE TAFS BUT THE TIMING MAY NEED TO BE ADJUSTED AS DETAILS BECOME MORE CLEAR. CONDITIONS LOWERING TO IFR OVERNIGHT AS A SURFACE COLD FRONT MOVES ACROSS THE AREA AND SHIFTS THE WINDS TO WEST TO NORTHWEST. COLDER AIR BEHIND THE FRONT WILL TURN THE REMAINING PRECIPITATION TO SN ON WEDNESDAY. PAW //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN IFR TIMING. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
149 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 1110 AM CST CONTINUE TO MONITOR ENVIRONMENTAL AND RADAR TRENDS WITH AN INCREASE IN STORM COVERAGE EXPECTED ACROSS THE WESTERN FORECAST AREA FROM 1-3 PM WORKING EASTWARD THROUGH THE LATE AFTERNOON AND NIGHT. CONCERNS REMAIN FOR ESPECIALLY HEAVY RAIN BUT ALSO FOR POSSIBLE SEVERE STORMS. SATELLITE CHANNELS AND UPPER AIR PROFILES THIS MORNING SHOW A SHORT WAVE-LADEN ATMOSPHERIC RIVER ANCHORED FROM THE SOUTHERN PLAIN ACROSS THE AREA AHEAD OF THE DEEP UPPER TROUGH. A COUPLE IMPULSES RESPONSIBLE FOR EARLIER MORNING CONVECTION HAVE PASSED INTO MI. RIGHT NOW THE FORECAST AREA IS IN A BIT OF A LULL THAT LOOKS TO LAST THROUGH THE NOON HOUR. A COUPLE MORE WAVES...EACH SUCCESSIVE ONE A LITTLE BETTER DEFINED ON WATER VAPOR...ARE SEEN FROM WESTERN MO THROUGH CENTRAL OK. AT THE SURFACE...THE COLD FRONT IS NOT FAR AWAY...INTO SOUTHWEST WI EXTENDING SOUTHWEST INTO WESTERN MO. THE FRONT HAS AND WILL CONTINUE TO SLOW SOMEWHAT AS A STRONGER SUB 998MB SURFACE LOW DEVELOPS ACROSS OK INTO THE AFTERNOON. THE ONSET OF OUR CONVECTION IS WHAT LIKELY IS MOVING NORTHEAST OUT OF MO AHEAD OF ONE OF THE SHORT WAVES. VISIBLE SATELLITE INDICATES ENHANCED AND ORGANIZED CLOUD TOPS WITH THIS ACTIVITY AND A LOOSE MCS MAY BE TRYING TO EVOLVE. THIS CONVECTION AS WELL AS MORE DEVELOPING UNDER IMPROVING UPPER LEVEL FORCING AND LOWER-MID LEVEL CONVERGENCE SHOULD ENCOMPASS MUCH OF THE WESTERN FORECAST AREA MID TO LATE AFTERNOON. THINNING ON THE VISIBLE SATELLITE ACROSS THE SOUTHWEST FORECAST AREA LIKELY WILL ALLOW TEMPS TO REACH THE FORECAST MID-UPPER 60S. THE RAP FORECAST SOUNDINGS WITH MID 60S INDICATE SURFACE BASED CAPE OF 500-700 J/KG...INCLUDING ALL IMPORTANT LOW-LEVEL CAPE IN THESE SITUATIONS NEAR 100 J/KG. MORE THAN ENOUGH ANALYZED AND FORECAST DEEP LAYER AND LOW-LEVEL SHEAR OF 30-40 KT WILL SUPPORT ORGANIZED STORMS CAPABLE OF WIND AND ISOLATED TORNADOES...ESPECIALLY IF THE CAPE VALUES ARE ABLE TO REACH THE VALUES ABOVE OR HIGHER. THE SPC STORM SCALE ENSEMBLE OF OPPORTUNITY /SSEO/ DOES INCLUDE A FEW MEMBERS INDICATING HIGHER UPDRAFT HELICITY IN THIS AREA DURING THE MID TO LATE AFTERNOON...A GENERAL PROXY FOR ROTATING STORMS. THIS CONVECTION WILL GRADUALLY EVOLVE EAST LATE THIS AFTERNOON AND EVENING ALONG WITH REDEVELOPING/ALMOST BACK BUILDING DUE TO STRONG SUSTAINING MOISTURE TRANSPORT...CONVERGENCE...AND PARALLEL ORIENTED BULK SHEAR VECTORS TO THE MEAN STORM FLOW. THIS WOULD PUT MUCH OF THE EASTERN FORECAST AREA UNDER THE BEST CHANCES FOR HEAVY RAIN AND STRONGER STORMS AFTER 6 PM. HOWEVER...AROUND HALF OF THE EXPLICIT CONVECTIVE MODELS LOOKED AT DO DEVELOP SCATTERED CONVECTION 3-5 PM SOUTH OF INTERSTATE 80 NEAR KANKAKEE...GIBSON CITY...AND PONTIAC AREAS. LOW-LEVEL FLOW IS BACKED MORE HERE SO THIS WOULD BE AN AREA TO WATCH...BUT CONFIDENCE ON DEVELOPMENT IS LOW AT THIS TIME. DURING THE EVENING HOWEVER THE SEVERE WEATHER THREAT WILL REMAIN IN THE EASTERN HALF...ESPECIALLY SOUTH OF INTERSTATE 80 AS LOW-LEVEL SHEAR AND HELICITY ARE EXTREMELY HIGH. IF TEMPERATURES CAN SUSTAIN THEMSELVES AND NOT DROP MUCH THIS EVENING IN THOSE AREAS...THE SURFACE BASED CONVECTIVE THREAT FOR WIND AND ISOLATED TORNADOES WILL REMAIN. UPSTREAM CONVECTION ACROSS THE MODERATE RISK AREA COULD STEAL SOME OF THE POTENCY IN OUR CONVECTION BY MID TO LATE EVE...BUT CERTAINLY NOT THE HEAVY RAIN THREAT. AND THAT HEAVY RAIN THREAT LOOKS HIGH FOR TONIGHT. PRECIPITABLE WATERS ARE RUNNING RIGHT AT RECORD HIGHS FOR THE MONTH OF JANUARY /1.33/ AND ARE FORECAST TO SUSTAIN THEMSELVES TONIGHT WITH AMPLE REPLENISHMENT. CLASSIC HIGH PWAT AND MOISTURE TRANSPORT AND CONVERGENCE SIGNATURES POINT TOWARD WIDESPREAD 1-2.50 INCHES OF RAIN IN TRAINING CONVECTIVE ACTIVITY. THE SSEO INDICATES A SIX HOUR MEAN OF 1-1.50 INCHES JUST DURING THIS EVENING WHICH IS IMPRESSIVE FOR A SPREAD OF HIGH RES ENSEMBLES. WILL CONTINUE THE FLOOD WATCH AS IS. MTF && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * AN AREA OF SHOWERS AND THUNDERSTORMS APPROACHING ORD AND MDW FROM THE SOUTHWEST AT 20Z. MORE WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS MOVING IN LATER THIS AFTERNOON AND THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR CONDITIONS PREVAILING THIS AFTERNOON AND EVENING. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 18Z... A SERIES OF UPPER LEVEL WAVES HAS BEEN MOVING ACROSS THE AREA WITH PERIODS OF SHRA AND TSRA. THE NEXT OF THESE WAVES IS MOVING OUT OF THE SOUTHERN PLAINS AT MID DAY AND IS EXPECTED TO BRING A LARGE AREA OF RA/SHRA WITH EMBEDDED TSRA TO NORTHERN IL AND NORTHWEST IN LATE THIS AFTERNOON AND THROUGH THE EVENING. HAVE HIGHLIGHTED THE MOST LIKELY TIME FRAME IN THE TAFS BUT THE TIMING MAY NEED TO BE ADJUSTED AS DETAILS BECOME MORE CLEAR. CONDITIONS LOWERING TO IFR OVERNIGHT AS A SURFACE COLD FRONT MOVES ACROSS THE AREA AND SHIFTS THE WINDS TO WEST TO NORTHWEST. COLDER AIR BEHIND THE FRONT WILL TURN THE REMAINING PRECIPITATION TO SN ON WEDNESDAY. PAW //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN IFR TIMING. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
105 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 1110 AM CST CONTINUE TO MONITOR ENVIRONMENTAL AND RADAR TRENDS WITH AN INCREASE IN STORM COVERAGE EXPECTED ACROSS THE WESTERN FORECAST AREA FROM 1-3 PM WORKING EASTWARD THROUGH THE LATE AFTERNOON AND NIGHT. CONCERNS REMAIN FOR ESPECIALLY HEAVY RAIN BUT ALSO FOR POSSIBLE SEVERE STORMS. SATELLITE CHANNELS AND UPPER AIR PROFILES THIS MORNING SHOW A SHORT WAVE-LADEN ATMOSPHERIC RIVER ANCHORED FROM THE SOUTHERN PLAIN ACROSS THE AREA AHEAD OF THE DEEP UPPER TROUGH. A COUPLE IMPULSES RESPONSIBLE FOR EARLIER MORNING CONVECTION HAVE PASSED INTO MI. RIGHT NOW THE FORECAST AREA IS IN A BIT OF A LULL THAT LOOKS TO LAST THROUGH THE NOON HOUR. A COUPLE MORE WAVES...EACH SUCCESSIVE ONE A LITTLE BETTER DEFINED ON WATER VAPOR...ARE SEEN FROM WESTERN MO THROUGH CENTRAL OK. AT THE SURFACE...THE COLD FRONT IS NOT FAR AWAY...INTO SOUTHWEST WI EXTENDING SOUTHWEST INTO WESTERN MO. THE FRONT HAS AND WILL CONTINUE TO SLOW SOMEWHAT AS A STRONGER SUB 998MB SURFACE LOW DEVELOPS ACROSS OK INTO THE AFTERNOON. THE ONSET OF OUR CONVECTION IS WHAT LIKELY IS MOVING NORTHEAST OUT OF MO AHEAD OF ONE OF THE SHORT WAVES. VISIBLE SATELLITE INDICATES ENHANCED AND ORGANIZED CLOUD TOPS WITH THIS ACTIVITY AND A LOOSE MCS MAY BE TRYING TO EVOLVE. THIS CONVECTION AS WELL AS MORE DEVELOPING UNDER IMPROVING UPPER LEVEL FORCING AND LOWER-MID LEVEL CONVERGENCE SHOULD ENCOMPASS MUCH OF THE WESTERN FORECAST AREA MID TO LATE AFTERNOON. THINNING ON THE VISIBLE SATELLITE ACROSS THE SOUTHWEST FORECAST AREA LIKELY WILL ALLOW TEMPS TO REACH THE FORECAST MID-UPPER 60S. THE RAP FORECAST SOUNDINGS WITH MID 60S INDICATE SURFACE BASED CAPE OF 500-700 J/KG...INCLUDING ALL IMPORTANT LOW-LEVEL CAPE IN THESE SITUATIONS NEAR 100 J/KG. MORE THAN ENOUGH ANALYZED AND FORECAST DEEP LAYER AND LOW-LEVEL SHEAR OF 30-40 KT WILL SUPPORT ORGANIZED STORMS CAPABLE OF WIND AND ISOLATED TORNADOES...ESPECIALLY IF THE CAPE VALUES ARE ABLE TO REACH THE VALUES ABOVE OR HIGHER. THE SPC STORM SCALE ENSEMBLE OF OPPORTUNITY /SSEO/ DOES INCLUDE A FEW MEMBERS INDICATING HIGHER UPDRAFT HELICITY IN THIS AREA DURING THE MID TO LATE AFTERNOON...A GENERAL PROXY FOR ROTATING STORMS. THIS CONVECTION WILL GRADUALLY EVOLVE EAST LATE THIS AFTERNOON AND EVENING ALONG WITH REDEVELOPING/ALMOST BACK BUILDING DUE TO STRONG SUSTAINING MOISTURE TRANSPORT...CONVERGENCE...AND PARALLEL ORIENTED BULK SHEAR VECTORS TO THE MEAN STORM FLOW. THIS WOULD PUT MUCH OF THE EASTERN FORECAST AREA UNDER THE BEST CHANCES FOR HEAVY RAIN AND STRONGER STORMS AFTER 6 PM. HOWEVER...AROUND HALF OF THE EXPLICIT CONVECTIVE MODELS LOOKED AT DO DEVELOP SCATTERED CONVECTION 3-5 PM SOUTH OF INTERSTATE 80 NEAR KANKAKEE...GIBSON CITY...AND PONTIAC AREAS. LOW-LEVEL FLOW IS BACKED MORE HERE SO THIS WOULD BE AN AREA TO WATCH...BUT CONFIDENCE ON DEVELOPMENT IS LOW AT THIS TIME. DURING THE EVENING HOWEVER THE SEVERE WEATHER THREAT WILL REMAIN IN THE EASTERN HALF...ESPECIALLY SOUTH OF INTERSTATE 80 AS LOW-LEVEL SHEAR AND HELICITY ARE EXTREMELY HIGH. IF TEMPERATURES CAN SUSTAIN THEMSELVES AND NOT DROP MUCH THIS EVENING IN THOSE AREAS...THE SURFACE BASED CONVECTIVE THREAT FOR WIND AND ISOLATED TORNADOES WILL REMAIN. UPSTREAM CONVECTION ACROSS THE MODERATE RISK AREA COULD STEAL SOME OF THE POTENCY IN OUR CONVECTION BY MID TO LATE EVE...BUT CERTAINLY NOT THE HEAVY RAIN THREAT. AND THAT HEAVY RAIN THREAT LOOKS HIGH FOR TONIGHT. PRECIPITABLE WATERS ARE RUNNING RIGHT AT RECORD HIGHS FOR THE MONTH OF JANUARY /1.33/ AND ARE FORECAST TO SUSTAIN THEMSELVES TONIGHT WITH AMPLE REPLENISHMENT. CLASSIC HIGH PWAT AND MOISTURE TRANSPORT AND CONVERGENCE SIGNATURES POINT TOWARD WIDESPREAD 1-2.50 INCHES OF RAIN IN TRAINING CONVECTIVE ACTIVITY. THE SSEO INDICATES A SIX HOUR MEAN OF 1-1.50 INCHES JUST DURING THIS EVENING WHICH IS IMPRESSIVE FOR A SPREAD OF HIGH RES ENSEMBLES. WILL CONTINUE THE FLOOD WATCH AS IS. MTF && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AREA THROUGH MID AFTERNOON. MORE WIDESPREAD RAIN AND SCATTERED THUNDERSTORMS LATER THIS AFTERNOON THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR TO IFR CEILINGS PREVAILING TODAY. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 18Z... A SERIES OF UPPER LEVEL WAVES HAS BEEN MOVING ACROSS THE AREA WITH PERIODS OF SHRA AND TSRA. THE NEXT OF THESE WAVES IS MOVING OUT OF THE SOUTHERN PLAINS AT MID DAY AND IS EXPECTED TO BRING A LARGE AREA OF RA/SHRA WITH EMBEDDED TSRA TO NORTHERN IL AND NORTHWEST IN LATE THIS AFTERNOON AND THROUGH THE EVENING. HAVE HIGHLIGHTED THE MOST LIKELY TIME FRAME IN THE TAFS BUT THE TIMING MAY NEED TO BE ADJUSTED AS DETAILS BECOME MORE CLEAR. CONDITIONS LOWERING TO IFR OVERNIGHT AS A SURFACE COLD FRONT MOVES ACROSS THE AREA AND SHIFTS THE WINDS TO WEST TO NORTHWEST. COLDER AIR BEHIND THE FRONT WILL TURN THE REMAINING PRECIPITATION TO SN ON WEDNESDAY. PAW //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN CEILING TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1144 AM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 1110 AM CST CONTINUE TO MONITOR ENVIRONMENTAL AND RADAR TRENDS WITH AN INCREASE IN STORM COVERAGE EXPECTED ACROSS THE WESTERN FORECAST AREA FROM 1-3 PM WORKING EASTWARD THROUGH THE LATE AFTERNOON AND NIGHT. CONCERNS REMAIN FOR ESPECIALLY HEAVY RAIN BUT ALSO FOR POSSIBLE SEVERE STORMS. SATELLITE CHANNELS AND UPPER AIR PROFILES THIS MORNING SHOW A SHORT WAVE-LADEN ATMOSPHERIC RIVER ANCHORED FROM THE SOUTHERN PLAIN ACROSS THE AREA AHEAD OF THE DEEP UPPER TROUGH. A COUPLE IMPULSES RESPONSIBLE FOR EARLIER MORNING CONVECTION HAVE PASSED INTO MI. RIGHT NOW THE FORECAST AREA IS IN A BIT OF A LULL THAT LOOKS TO LAST THROUGH THE NOON HOUR. A COUPLE MORE WAVES...EACH SUCCESSIVE ONE A LITTLE BETTER DEFINED ON WATER VAPOR...ARE SEEN FROM WESTERN MO THROUGH CENTRAL OK. AT THE SURFACE...THE COLD FRONT IS NOT FAR AWAY...INTO SOUTHWEST WI EXTENDING SOUTHWEST INTO WESTERN MO. THE FRONT HAS AND WILL CONTINUE TO SLOW SOMEWHAT AS A STRONGER SUB 998MB SURFACE LOW DEVELOPS ACROSS OK INTO THE AFTERNOON. THE ONSET OF OUR CONVECTION IS WHAT LIKELY IS MOVING NORTHEAST OUT OF MO AHEAD OF ONE OF THE SHORT WAVES. VISIBLE SATELLITE INDICATES ENHANCED AND ORGANIZED CLOUD TOPS WITH THIS ACTIVITY AND A LOOSE MCS MAY BE TRYING TO EVOLVE. THIS CONVECTION AS WELL AS MORE DEVELOPING UNDER IMPROVING UPPER LEVEL FORCING AND LOWER-MID LEVEL CONVERGENCE SHOULD ENCOMPASS MUCH OF THE WESTERN FORECAST AREA MID TO LATE AFTERNOON. THINNING ON THE VISIBLE SATELLITE ACROSS THE SOUTHWEST FORECAST AREA LIKELY WILL ALLOW TEMPS TO REACH THE FORECAST MID-UPPER 60S. THE RAP FORECAST SOUNDINGS WITH MID 60S INDICATE SURFACE BASED CAPE OF 500-700 J/KG...INCLUDING ALL IMPORTANT LOW-LEVEL CAPE IN THESE SITUATIONS NEAR 100 J/KG. MORE THAN ENOUGH ANALYZED AND FORECAST DEEP LAYER AND LOW-LEVEL SHEAR OF 30-40 KT WILL SUPPORT ORGANIZED STORMS CAPABLE OF WIND AND ISOLATED TORNADOES...ESPECIALLY IF THE CAPE VALUES ARE ABLE TO REACH THE VALUES ABOVE OR HIGHER. THE SPC STORM SCALE ENSEMBLE OF OPPORTUNITY /SSEO/ DOES INCLUDE A FEW MEMBERS INDICATING HIGHER UPDRAFT HELICITY IN THIS AREA DURING THE MID TO LATE AFTERNOON...A GENERAL PROXY FOR ROTATING STORMS. THIS CONVECTION WILL GRADUALLY EVOLVE EAST LATE THIS AFTERNOON AND EVENING ALONG WITH REDEVELOPING/ALMOST BACK BUILDING DUE TO STRONG SUSTAINING MOISTURE TRANSPORT...CONVERGENCE...AND PARALLEL ORIENTED BULK SHEAR VECTORS TO THE MEAN STORM FLOW. THIS WOULD PUT MUCH OF THE EASTERN FORECAST AREA UNDER THE BEST CHANCES FOR HEAVY RAIN AND STRONGER STORMS AFTER 6 PM. HOWEVER...AROUND HALF OF THE EXPLICIT CONVECTIVE MODELS LOOKED AT DO DEVELOP SCATTERED CONVECTION 3-5 PM SOUTH OF INTERSTATE 80 NEAR KANKAKEE...GIBSON CITY...AND PONTIAC AREAS. LOW-LEVEL FLOW IS BACKED MORE HERE SO THIS WOULD BE AN AREA TO WATCH...BUT CONFIDENCE ON DEVELOPMENT IS LOW AT THIS TIME. DURING THE EVENING HOWEVER THE SEVERE WEATHER THREAT WILL REMAIN IN THE EASTERN HALF...ESPECIALLY SOUTH OF INTERSTATE 80 AS LOW-LEVEL SHEAR AND HELICITY ARE EXTREMELY HIGH. IF TEMPERATURES CAN SUSTAIN THEMSELVES AND NOT DROP MUCH THIS EVENING IN THOSE AREAS...THE SURFACE BASED CONVECTIVE THREAT FOR WIND AND ISOLATED TORNADOES WILL REMAIN. UPSTREAM CONVECTION ACROSS THE MODERATE RISK AREA COULD STEAL SOME OF THE POTENCY IN OUR CONVECTION BY MID TO LATE EVE...BUT CERTAINLY NOT THE HEAVY RAIN THREAT. AND THAT HEAVY RAIN THREAT LOOKS HIGH FOR TONIGHT. PRECIPITABLE WATERS ARE RUNNING RIGHT AT RECORD HIGHS FOR THE MONTH OF JANUARY /1.33/ AND ARE FORECAST TO SUSTAIN THEMSELVES TONIGHT WITH AMPLE REPLENISHMENT. CLASSIC HIGH PWAT AND MOISTURE TRANSPORT AND CONVERGENCE SIGNATURES POINT TOWARD WIDESPREAD 1-2.50 INCHES OF RAIN IN TRAINING CONVECTIVE ACTIVITY. THE SSEO INDICATES A SIX HOUR MEAN OF 1-1.50 INCHES JUST DURING THIS EVENING WHICH IS IMPRESSIVE FOR A SPREAD OF HIGH RES ENSEMBLES. WILL CONTINUE THE FLOOD WATCH AS IS. MTF && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AREA THROUGH MID AFTERNOON. MORE WIDESPREAD RAIN AND SCATTERED THUNDERSTORMS LATER THIS AFTERNOON THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR TO IFR CEILINGS PREVAILING TODAY. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 18Z... A SERIES OF UPPER LEVEL WAVES HAS BEEN MOVING ACROSS THE AREA WITH PERIODS OF SHRA AND TSRA. THE NEXT OF THESE WAVES IS MOVING OUT OF THE SOUTHERN PLAINS AT MID DAY AND IS EXPECTED TO BRING A LARGE AREA OF RA/SHRA WITH EMBEDDED TSRA TO NORTHERN IL AND NORTHWEST IN LATE THIS AFTERNOON AND THROUGH THE EVENING. HAVE HIGHLIGHTED THE MOST LIKELY TIME FRAME IN THE TAFS BUT THE TIMING MAY NEED TO BE ADJUSTED AS DETAILS BECOME MORE CLEAR. CONDITIONS LOWERING TO IFR OVERNIGHT AS A SURFACE COLD FRONT MOVES ACROSS THE AREA AND SHIFTS THE WINDS TO WEST TO NORTHWEST. COLDER AIR BEHIND THE FRONT WILL TURN THE REMAINING PRECIPITATION TO SN ON WEDNESDAY. PAW //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN CEILING TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 300 AM CST LOW PRESSURE INCHES OVER IOWA...WILL CONTINUE TO TRACK NORTHEAST TO SOUTHERN ONTARIO BY THIS EVENING...DRAGGING A WARM FRONT NORTH ACROSS LAKE MICHIGAN...BRINGING A SURGE OF UNSEASONABLY WARM AND HUMID AIR TO THE GREAT LAKES. AN ASSOCIATED COLD FRONT TRAILS BACK TO ANOTHER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THIS SECOND LOW IS EXPECTED TO TRACK NORTHEAST ACROSS THE FAR SOUTHERN TIP OF THE LAKE LATE TONIGHT WHILE DRAGGING A STRONG COLD FRONT IN IT`S WAKE. FOLLOWING THE PASSAGE OF THIS SYSTEM...COLD HIGH PRESSURE WILL BUILD OUT OF CANADA AND SPREAD ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT. THE COMBINATION OF THE EXITING LOW...THE BUILDING HIGH AND THE INFLUX OF MUCH COOLER AIR WILL BRING NORTHWEST GALES TO THE ENTIRE LAKE BY WEDNESDAY MORNING. GALES SHOULD PERSIST OVER THE LAKE THROUGH LATE WEDNESDAY NIGHT. THE HIGH PRESSURE WILL THEN SPREAD INTO THE CENTRAL PLAINS AND MISSOURI VALLEY ON THURSDAY. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1112 AM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 1110 AM CST CONTINUE TO MONITOR ENVIRONMENTAL AND RADAR TRENDS WITH AN INCREASE IN STORM COVERAGE EXPECTED ACROSS THE WESTERN FORECAST AREA FROM 1-3 PM WORKING EASTWARD THROUGH THE LATE AFTERNOON AND NIGHT. CONCERNS REMAIN FOR ESPECIALLY HEAVY RAIN BUT ALSO FOR POSSIBLE SEVERE STORMS. SATELLITE CHANNELS AND UPPER AIR PROFILES THIS MORNING SHOW A SHORT WAVE-LADEN ATMOSPHERIC RIVER ANCHORED FROM THE SOUTHERN PLAIN ACROSS THE AREA AHEAD OF THE DEEP UPPER TROUGH. A COUPLE IMPULSES RESPONSIBLE FOR EARLIER MORNING CONVECTION HAVE PASSED INTO MI. RIGHT NOW THE FORECAST AREA IS IN A BIT OF A LULL THAT LOOKS TO LAST THROUGH THE NOON HOUR. A COUPLE MORE WAVES...EACH SUCCESSIVE ONE A LITTLE BETTER DEFINED ON WATER VAPOR...ARE SEEN FROM WESTERN MO THROUGH CENTRAL OK. AT THE SURFACE...THE COLD FRONT IS NOT FAR AWAY...INTO SOUTHWEST WI EXTENDING SOUTHWEST INTO WESTERN MO. THE FRONT HAS AND WILL CONTINUE TO SLOW SOMEWHAT AS A STRONGER SUB 998MB SURFACE LOW DEVELOPS ACROSS OK INTO THE AFTERNOON. THE ONSET OF OUR CONVECTION IS WHAT LIKELY IS MOVING NORTHEAST OUT OF MO AHEAD OF ONE OF THE SHORT WAVES. VISIBLE SATELLITE INDICATES ENHANCED AND ORGANIZED CLOUD TOPS WITH THIS ACTIVITY AND A LOOSE MCS MAY BE TRYING TO EVOLVE. THIS CONVECTION AS WELL AS MORE DEVELOPING UNDER IMPROVING UPPER LEVEL FORCING AND LOWER-MID LEVEL CONVERGENCE SHOULD ENCOMPASS MUCH OF THE WESTERN FORECAST AREA MID TO LATE AFTERNOON. THINNING ON THE VISIBLE SATELLITE ACROSS THE SOUTHWEST FORECAST AREA LIKELY WILL ALLOW TEMPS TO REACH THE FORECAST MID-UPPER 60S. THE RAP FORECAST SOUNDINGS WITH MID 60S INDICATE SURFACE BASED CAPE OF 500-700 J/KG...INCLUDING ALL IMPORTANT LOW-LEVEL CAPE IN THESE SITUATIONS NEAR 100 J/KG. MORE THAN ENOUGH ANALYZED AND FORECAST DEEP LAYER AND LOW-LEVEL SHEAR OF 30-40 KT WILL SUPPORT ORGANIZED STORMS CAPABLE OF WIND AND ISOLATED TORNADOES...ESPECIALLY IF THE CAPE VALUES ARE ABLE TO REACH THE VALUES ABOVE OR HIGHER. THE SPC STORM SCALE ENSEMBLE OF OPPORTUNITY /SSEO/ DOES INCLUDE A FEW MEMBERS INDICATING HIGHER UPDRAFT HELICITY IN THIS AREA DURING THE MID TO LATE AFTERNOON...A GENERAL PROXY FOR ROTATING STORMS. THIS CONVECTION WILL GRADUALLY EVOLVE EAST LATE THIS AFTERNOON AND EVENING ALONG WITH REDEVELOPING/ALMOST BACK BUILDING DUE TO STRONG SUSTAINING MOISTURE TRANSPORT...CONVERGENCE...AND PARALLEL ORIENTED BULK SHEAR VECTORS TO THE MEAN STORM FLOW. THIS WOULD PUT MUCH OF THE EASTERN FORECAST AREA UNDER THE BEST CHANCES FOR HEAVY RAIN AND STRONGER STORMS AFTER 6 PM. HOWEVER...AROUND HALF OF THE EXPLICIT CONVECTIVE MODELS LOOKED AT DO DEVELOP SCATTERED CONVECTION 3-5 PM SOUTH OF INTERSTATE 80 NEAR KANKAKEE...GIBSON CITY...AND PONTIAC AREAS. LOW-LEVEL FLOW IS BACKED MORE HERE SO THIS WOULD BE AN AREA TO WATCH...BUT CONFIDENCE ON DEVELOPMENT IS LOW AT THIS TIME. DURING THE EVENING HOWEVER THE SEVERE WEATHER THREAT WILL REMAIN IN THE EASTERN HALF...ESPECIALLY SOUTH OF INTERSTATE 80 AS LOW-LEVEL SHEAR AND HELICITY ARE EXTREMELY HIGH. IF TEMPERATURES CAN SUSTAIN THEMSELVES AND NOT DROP MUCH THIS EVENING IN THOSE AREAS...THE SURFACE BASED CONVECTIVE THREAT FOR WIND AND ISOLATED TORNADOES WILL REMAIN. UPSTREAM CONVECTION ACROSS THE MODERATE RISK AREA COULD STEAL SOME OF THE POTENCY IN OUR CONVECTION BY MID TO LATE EVE...BUT CERTAINLY NOT THE HEAVY RAIN THREAT. AND THAT HEAVY RAIN THREAT LOOKS HIGH FOR TONIGHT. PRECIPITABLE WATERS ARE RUNNING RIGHT AT RECORD HIGHS FOR THE MONTH OF JANUARY /1.33/ AND ARE FORECAST TO SUSTAIN THEMSELVES TONIGHT WITH AMPLE REPLENISHMENT. CLASSIC HIGH PWAT AND MOISTURE TRANSPORT AND CONVERGENCE SIGNATURES POINT TOWARD WIDESPREAD 1-2.50 INCHES OF RAIN IN TRAINING CONVECTIVE ACTIVITY. THE SSEO INDICATES A SIX HOUR MEAN OF 1-1.50 INCHES JUST DURING THIS EVENING WHICH IS IMPRESSIVE FOR A SPREAD OF HIGH RES ENSEMBLES. WILL CONTINUE THE FLOOD WATCH AS IS. MTF && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AREA THROUGH MID AFTERNOON. MORE WIDESPREAD RAIN AND SCATTERED THUNDERSTORMS LATER THIS AFTERNOON THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR CEILINGS PREVAILING TODAY. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 12Z... ANOTHER SHORT WAVE IS QUICKLY LIFTING NE FROM E CENTRAL IA AND WILL BE PASSING OVER NW AND N CENTRAL IL AND THEN ON TO S CENTRAL WI BY 15Z. THIS FEATURE WAS CONTINUING TO DEVELOP AND MAINTAIN SHOWERS AND THUNDERSTORMS...THAT ARE EXPECTED TO MOVE NE AND OUT OF NW AND N CENTRAL IL DURING THE EARLY MORNING. ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED AS STRONG SSW-SW FLOW IN THE LOWER AND MID LEVELS CONTINUES TO RESULT IN ISENTROPIC UPGLIDE. HOWEVER...THEY ARE EXPECTED TO BE MAINLY ACROSS SE AND E CENTRAL IA...NW IL AND N CENTRAL IL...AND SW AND S CENTRAL WI AS THIS IS WHERE THE AXIS OF GREATEST INSTABILITY IS LOCATED. FORECAST REFLECTIVITY FROM THE 08Z RUN OF THE HRRR HAD A GOOD DEPICTION OF WHERE MAIN ACTIVITY WAS OCCURRING OVER THE LAST FEW HOURS. LOOP OF REFLECTIVITY KEEPS THE TERMINALS MAINLY DRY THROUGH MUCH OF THE DAY WITH A SW-NE BAND OF RAIN AND THUNDERSTORMS AROUND 75 MILES W THROUGH N OF THE CHICAGO AREA AND ANOTHER BAND FORM 70 MILES SE TO 150 MILES SW OF ORD AND MDW. THE WARM FRONT PUSHED N TO THE WI BORDER AT 12Z. THIS RESULTED IN A WIND SHIFT TO OUT OF THE S-SSW AND A RAPID CLEARING OUT OF THE FOG THAT BLANKED THE AREA LAST EVENING AND INTO THE LATE OVERNIGHT HOURS. THE WIDESPREAD LIFR CEILINGS HAVE ALSO IMPROVED BUT NOT AS QUICKLY AS ARE CURRENTLY MAINLY MVFR. CEILINGS WILL RISE A BIT MORE TO HIGHER END MVFR BY LATE MORNING. THERE MAY BE SOME PERIODS OF VFR AS HOLES IN THE STRATOCU MOVE ACROSS THE AREA. A MID LEVEL TROUGH CONTINUES TO PROGRESS EASTWARD TODAY WITH ITS AXIS REACHING A N CENTRAL MN TO TX PANHANDLE LINE BY 00Z...AND A NE MN TO CENTRAL OK LINE BY 06Z. ANOTHER SHORT WAVE WAS CURRENTLY LIFTING NE FROM OK AND IS PROGGED TO REACH IA AND MO BY 00Z. INCREASING LIFT AHEAD OF THE TROUGH AXIS ALONG WITH LOW LEVEL CONVERGENCE ALONG AND S OF A SLOWLY ADVANCING COLD FRONT AS THE ASSOCIATED SURFACE LOW RIDES NE ALONG THE BOUNDARY PROGGED TO BE FROM NORTHERN LAKE MI SW TO LOW PRESSURE IN NE MO BY EVENING WILL CONTINUE TO SPREAD AN INCREASING AREA OF RAIN AND THUNDERSTORMS INTO THE LOCAL AREA DURING THE LATER AFTERNOON. THE AREA OF PRECIPITATION WILL BE SHIFTING NE AND E ACROSS THE LOCAL AREA DURING THE EARLY TO MID EVENING AS THE SURFACE LOW CONTINUES NE ALONG THE BOUNDARY TO SOUTHERN LAKE MI PULLING A COLD FRONT ACROSS NW AND FAR NE IL BY 06Z. S TO SW WINDS SHOULD CONTINUE TO GUST AT 20-25KT THROUGH THE DAY THEN DIMINISH THIS EVENING AS THE PRESSURE GRADIENT DECREASES AS THE FRONT APPROACHES. THE COLD FRONT IS EXPECTED TO PASS ACROSS THE LOCAL AREA AROUND 07Z WITH A WIND SHIFT TO OUT OF THE W AND NW. IFR TO LIFR CONDITIONS ARE ANTICIPATED TO RETURN FOR LATER EVENING AND OVERNIGHT. TRS //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN CEILING TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 300 AM CST LOW PRESSURE INCHES OVER IOWA...WILL CONTINUE TO TRACK NORTHEAST TO SOUTHERN ONTARIO BY THIS EVENING...DRAGGING A WARM FRONT NORTH ACROSS LAKE MICHIGAN...BRINGING A SURGE OF UNSEASONABLY WARM AND HUMID AIR TO THE GREAT LAKES. AN ASSOCIATED COLD FRONT TRAILS BACK TO ANOTHER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THIS SECOND LOW IS EXPECTED TO TRACK NORTHEAST ACROSS THE FAR SOUTHERN TIP OF THE LAKE LATE TONIGHT WHILE DRAGGING A STRONG COLD FRONT IN IT`S WAKE. FOLLOWING THE PASSAGE OF THIS SYSTEM...COLD HIGH PRESSURE WILL BUILD OUT OF CANADA AND SPREAD ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT. THE COMBINATION OF THE EXITING LOW...THE BUILDING HIGH AND THE INFLUX OF MUCH COOLER AIR WILL BRING NORTHWEST GALES TO THE ENTIRE LAKE BY WEDNESDAY MORNING. GALES SHOULD PERSIST OVER THE LAKE THROUGH LATE WEDNESDAY NIGHT. THE HIGH PRESSURE WILL THEN SPREAD INTO THE CENTRAL PLAINS AND MISSOURI VALLEY ON THURSDAY. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1005 AM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 538 AM CST A COUPLE OF LATE THOUGHTS ON THE SEVERE WEATHER POTENTIAL LATER THIS AFTERNOON. SUBTLE SHORTWAVE IN THE SOUTHWEST FLOW IS BECOMING A BIT MORE APPARENT THIS MORNING OVER EASTERN IOWA/NORTHERN MO WITH AN INCREASE IN SCTD CONVECTION ASSOCIATED WITH THIS FEATURE. AS THIS WAVE MOVES THROUGH THIS MORNING WOULD ANTICIPATE AN INCREASE IN THE COVERAGE OF SHOWERS AND STORMS WITH EXTRAPOLATION HAVING THIS WAVE OUT OF OUR EASTERN CWA BY 15-16Z. IN THE WAKE OF THIS WEAK WAVE COULD SEE A BIT OF A LULL IN CONVECTION AND MAYBE A THINNING OF CLOUD COVER AND SOME FILTERED SUNSHINE OR AT LEAST WEAK HEATING. AS ALLUDED TO IN THE EARLIER AFD...LAPSE RATES ARE WEAK AND NOT EXPECTED TO IMPROVE MUCH TODAY. WHILE MODELS ARE FORECAST LITTLE TO NO SURFACE BASED CAPE TODAY...THEY ARE ALSO LIKELY UNDER-DOING SURFACE TEMPS BY HOLDING READINGS IN THE UPPER 50S ALL AFTERNOON. ASSUMING FORECAST HIGHS IN THE MID 60S ARE ACHIEVED THEN A FEW HUNDRED JOULES OF SBCAPE COULD BE REALIZED THIS AFTERNOON AHEAD OF THE MORE VIGOROUS SHORT WHICH IS EXPECTED TO IGNITE CONVECTION JUST TO OUR WEST THIS AFTERNOON. ASSUMING WEAK SURFACE BASED INSTABILITY DOES INDEED MATERIALIZE...THEN LOW AND DEEP LAYER SHEAR WOULD BE EXCEPTIONALLY SUPPORTIVE OF SEVERE THUNDERSTORMS WITH A WIND DAMAGE AND POTENTIALLY A LOW END TORNADO THREAT. THE SEVERE RISK TODAY IS CERTAINLY A VERY CONDITIONAL ONE BASED LARGELY ON WHETHER SOME WEAK DESTABILIZATION CAN OCCUR AND ALSO THAT FORCING CAN HELP COMPENSATE FOR THE WEAK INSTABILITY TO ALLOW FOR UPRIGHT DRAFTS THAT ARE NOT SHEARED APART. WHILE THE SEVERE RISK THIS AFTERNOON AND EVENING DOES NOT APPEAR HUGE AT THIS TIME...THE DIFFERENCE BETWEEN NOTHING AND TORNADOES IS ONLY A FEW HUNDRED JOULES OF CAPE AND THE RIGHT STORM MODE...BOTH OF WHICH ARE VERY DIFFICULT TO PREDICT BEYOND THE VERY NEAR TERM. WANTED TO ADD THIS SHORT ADDITION TO THE AFD BECAUSE I FEARED I MAY HAVE UNINTENTIONALLY DOWNPLAYED THE SEVERE THREAT A BIT TOO MUCH IN THE INITIAL MORNING AFD. IZZI && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AREA THROUGH MID AFTERNOON. MORE WIDESPREAD RAIN AND SCATTERED THUNDERSTORMS LATER THIS AFTERNOON THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS..GUSTING TO 20-25 KT THROUGH THE AFTERNOON. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR CEILINGS PREVAILING TODAY. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 12Z... ANOTHER SHORT WAVE IS QUICKLY LIFTING NE FROM E CENTRAL IA AND WILL BE PASSING OVER NW AND N CENTRAL IL AND THEN ON TO S CENTRAL WI BY 15Z. THIS FEATURE WAS CONTINUING TO DEVELOP AND MAINTAIN SHOWERS AND THUNDERSTORMS...THAT ARE EXPECTED TO MOVE NE AND OUT OF NW AND N CENTRAL IL DURING THE EARLY MORNING. ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED AS STRONG SSW-SW FLOW IN THE LOWER AND MID LEVELS CONTINUES TO RESULT IN ISENTROPIC UPGLIDE. HOWEVER...THEY ARE EXPECTED TO BE MAINLY ACROSS SE AND E CENTRAL IA...NW IL AND N CENTRAL IL...AND SW AND S CENTRAL WI AS THIS IS WHERE THE AXIS OF GREATEST INSTABILITY IS LOCATED. FORECAST REFLECTIVITY FROM THE 08Z RUN OF THE HRRR HAD A GOOD DEPICTION OF WHERE MAIN ACTIVITY WAS OCCURRING OVER THE LAST FEW HOURS. LOOP OF REFLECTIVITY KEEPS THE TERMINALS MAINLY DRY THROUGH MUCH OF THE DAY WITH A SW-NE BAND OF RAIN AND THUNDERSTORMS AROUND 75 MILES W THROUGH N OF THE CHICAGO AREA AND ANOTHER BAND FORM 70 MILES SE TO 150 MILES SW OF ORD AND MDW. THE WARM FRONT PUSHED N TO THE WI BORDER AT 12Z. THIS RESULTED IN A WIND SHIFT TO OUT OF THE S-SSW AND A RAPID CLEARING OUT OF THE FOG THAT BLANKED THE AREA LAST EVENING AND INTO THE LATE OVERNIGHT HOURS. THE WIDESPREAD LIFR CEILINGS HAVE ALSO IMPROVED BUT NOT AS QUICKLY AS ARE CURRENTLY MAINLY MVFR. CEILINGS WILL RISE A BIT MORE TO HIGHER END MVFR BY LATE MORNING. THERE MAY BE SOME PERIODS OF VFR AS HOLES IN THE STRATOCU MOVE ACROSS THE AREA. A MID LEVEL TROUGH CONTINUES TO PROGRESS EASTWARD TODAY WITH ITS AXIS REACHING A N CENTRAL MN TO TX PANHANDLE LINE BY 00Z...AND A NE MN TO CENTRAL OK LINE BY 06Z. ANOTHER SHORT WAVE WAS CURRENTLY LIFTING NE FROM OK AND IS PROGGED TO REACH IA AND MO BY 00Z. INCREASING LIFT AHEAD OF THE TROUGH AXIS ALONG WITH LOW LEVEL CONVERGENCE ALONG AND S OF A SLOWLY ADVANCING COLD FRONT AS THE ASSOCIATED SURFACE LOW RIDES NE ALONG THE BOUNDARY PROGGED TO BE FROM NORTHERN LAKE MI SW TO LOW PRESSURE IN NE MO BY EVENING WILL CONTINUE TO SPREAD AN INCREASING AREA OF RAIN AND THUNDERSTORMS INTO THE LOCAL AREA DURING THE LATER AFTERNOON. THE AREA OF PRECIPITATION WILL BE SHIFTING NE AND E ACROSS THE LOCAL AREA DURING THE EARLY TO MID EVENING AS THE SURFACE LOW CONTINUES NE ALONG THE BOUNDARY TO SOUTHERN LAKE MI PULLING A COLD FRONT ACROSS NW AND FAR NE IL BY 06Z. S TO SW WINDS SHOULD CONTINUE TO GUST AT 20-25KT THROUGH THE DAY THEN DIMINISH THIS EVENING AS THE PRESSURE GRADIENT DECREASES AS THE FRONT APPROACHES. THE COLD FRONT IS EXPECTED TO PASS ACROSS THE LOCAL AREA AROUND 07Z WITH A WIND SHIFT TO OUT OF THE W AND NW. IFR TO LIFR CONDITIONS ARE ANTICIPATED TO RETURN FOR LATER EVENING AND OVERNIGHT. TRS //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM TREND. MEDIUM CONFIDENCE IN TIMING OF MORE WIDESPREAD ACTIVITY LATER THIS AFTERNOON AND EVENING...AND IN CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN CEILING TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 300 AM CST LOW PRESSURE INCHES OVER IOWA...WILL CONTINUE TO TRACK NORTHEAST TO SOUTHERN ONTARIO BY THIS EVENING...DRAGGING A WARM FRONT NORTH ACROSS LAKE MICHIGAN...BRINGING A SURGE OF UNSEASONABLY WARM AND HUMID AIR TO THE GREAT LAKES. AN ASSOCIATED COLD FRONT TRAILS BACK TO ANOTHER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THIS SECOND LOW IS EXPECTED TO TRACK NORTHEAST ACROSS THE FAR SOUTHERN TIP OF THE LAKE LATE TONIGHT WHILE DRAGGING A STRONG COLD FRONT IN IT`S WAKE. FOLLOWING THE PASSAGE OF THIS SYSTEM...COLD HIGH PRESSURE WILL BUILD OUT OF CANADA AND SPREAD ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT. THE COMBINATION OF THE EXITING LOW...THE BUILDING HIGH AND THE INFLUX OF MUCH COOLER AIR WILL BRING NORTHWEST GALES TO THE ENTIRE LAKE BY WEDNESDAY MORNING. GALES SHOULD PERSIST OVER THE LAKE THROUGH LATE WEDNESDAY NIGHT. THE HIGH PRESSURE WILL THEN SPREAD INTO THE CENTRAL PLAINS AND MISSOURI VALLEY ON THURSDAY. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
811 AM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 538 AM CST A COUPLE OF LATE THOUGHTS ON THE SEVERE WEATHER POTENTIAL LATER THIS AFTERNOON. SUBTLE SHORTWAVE IN THE SOUTHWEST FLOW IS BECOMING A BIT MORE APPARENT THIS MORNING OVER EASTERN IOWA/NORTHERN MO WITH AN INCREASE IN SCTD CONVECTION ASSOCIATED WITH THIS FEATURE. AS THIS WAVE MOVES THROUGH THIS MORNING WOULD ANTICIPATE AN INCREASE IN THE COVERAGE OF SHOWERS AND STORMS WITH EXTRAPOLATION HAVING THIS WAVE OUT OF OUR EASTERN CWA BY 15-16Z. IN THE WAKE OF THIS WEAK WAVE COULD SEE A BIT OF A LULL IN CONVECTION AND MAYBE A THINNING OF CLOUD COVER AND SOME FILTERED SUNSHINE OR AT LEAST WEAK HEATING. AS ALLUDED TO IN THE EARLIER AFD...LAPSE RATES ARE WEAK AND NOT EXPECTED TO IMPROVE MUCH TODAY. WHILE MODELS ARE FORECAST LITTLE TO NO SURFACE BASED CAPE TODAY...THEY ARE ALSO LIKELY UNDER-DOING SURFACE TEMPS BY HOLDING READINGS IN THE UPPER 50S ALL AFTERNOON. ASSUMING FORECAST HIGHS IN THE MID 60S ARE ACHIEVED THEN A FEW HUNDRED JOULES OF SBCAPE COULD BE REALIZED THIS AFTERNOON AHEAD OF THE MORE VIGOROUS SHORT WHICH IS EXPECTED TO IGNITE CONVECTION JUST TO OUR WEST THIS AFTERNOON. ASSUMING WEAK SURFACE BASED INSTABILITY DOES INDEED MATERIALIZE...THEN LOW AND DEEP LAYER SHEAR WOULD BE EXCEPTIONALLY SUPPORTIVE OF SEVERE THUNDERSTORMS WITH A WIND DAMAGE AND POTENTIALLY A LOW END TORNADO THREAT. THE SEVERE RISK TODAY IS CERTAINLY A VERY CONDITIONAL ONE BASED LARGELY ON WHETHER SOME WEAK DESTABILIZATION CAN OCCUR AND ALSO THAT FORCING CAN HELP COMPENSATE FOR THE WEAK INSTABILITY TO ALLOW FOR UPRIGHT DRAFTS THAT ARE NOT SHEARED APART. WHILE THE SEVERE RISK THIS AFTERNOON AND EVENING DOES NOT APPEAR HUGE AT THIS TIME...THE DIFFERENCE BETWEEN NOTHING AND TORNADOES IS ONLY A FEW HUNDRED JOULES OF CAPE AND THE RIGHT STORM MODE...BOTH OF WHICH ARE VERY DIFFICULT TO PREDICT BEYOND THE VERY NEAR TERM. WANTED TO ADD THIS SHORT ADDITION TO THE AFD BECAUSE I FEARED I MAY HAVE UNINTENTIONALLY DOWNPLAYED THE SEVERE THREAT A BIT TOO MUCH IN THE INITIAL MORNING AFD. IZZI && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AREA THROUGH MID AFTERNOON. MORE WIDESPREAD RAIN AND SCATTERED THUNDERSTORMS LATER THIS AFTERNOON THROUGH THE EVENING. * SOUTH TO SOUTHWEST WINDS GUSTING TO 20-25 KT DURING THE DAY. WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES ACROSS THE AREA. * MVFR CEILINGS PREVAILING TODAY. IFR CONDITIONS TONIGHT. PAW //DISCUSSION...UPDATED 12Z... ANOTHER SHORT WAVE IS QUICKLY LIFTING NE FROM E CENTRAL IA AND WILL BE PASSING OVER NW AND N CENTRAL IL AND THEN ON TO S CENTRAL WI BY 15Z. THIS FEATURE WAS CONTINUING TO DEVELOP AND MAINTAIN SHOWERS AND THUNDERSTORMS...THAT ARE EXPECTED TO MOVE NE AND OUT OF NW AND N CENTRAL IL DURING THE EARLY MORNING. ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED AS STRONG SSW-SW FLOW IN THE LOWER AND MID LEVELS CONTINUES TO RESULT IN ISENTROPIC UPGLIDE. HOWEVER...THEY ARE EXPECTED TO BE MAINLY ACROSS SE AND E CENTRAL IA...NW IL AND N CENTRAL IL...AND SW AND S CENTRAL WI AS THIS IS WHERE THE AXIS OF GREATEST INSTABILITY IS LOCATED. FORECAST REFLECTIVITY FROM THE 08Z RUN OF THE HRRR HAD A GOOD DEPICTION OF WHERE MAIN ACTIVITY WAS OCCURRING OVER THE LAST FEW HOURS. LOOP OF REFLECTIVITY KEEPS THE TERMINALS MAINLY DRY THROUGH MUCH OF THE DAY WITH A SW-NE BAND OF RAIN AND THUNDERSTORMS AROUND 75 MILES W THROUGH N OF THE CHICAGO AREA AND ANOTHER BAND FORM 70 MILES SE TO 150 MILES SW OF ORD AND MDW. THE WARM FRONT PUSHED N TO THE WI BORDER AT 12Z. THIS RESULTED IN A WIND SHIFT TO OUT OF THE S-SSW AND A RAPID CLEARING OUT OF THE FOG THAT BLANKED THE AREA LAST EVENING AND INTO THE LATE OVERNIGHT HOURS. THE WIDESPREAD LIFR CEILINGS HAVE ALSO IMPROVED BUT NOT AS QUICKLY AS ARE CURRENTLY MAINLY MVFR. CEILINGS WILL RISE A BIT MORE TO HIGHER END MVFR BY LATE MORNING. THERE MAY BE SOME PERIODS OF VFR AS HOLES IN THE STRATOCU MOVE ACROSS THE AREA. A MID LEVEL TROUGH CONTINUES TO PROGRESS EASTWARD TODAY WITH ITS AXIS REACHING A N CENTRAL MN TO TX PANHANDLE LINE BY 00Z...AND A NE MN TO CENTRAL OK LINE BY 06Z. ANOTHER SHORT WAVE WAS CURRENTLY LIFTING NE FROM OK AND IS PROGGED TO REACH IA AND MO BY 00Z. INCREASING LIFT AHEAD OF THE TROUGH AXIS ALONG WITH LOW LEVEL CONVERGENCE ALONG AND S OF A SLOWLY ADVANCING COLD FRONT AS THE ASSOCIATED SURFACE LOW RIDES NE ALONG THE BOUNDARY PROGGED TO BE FROM NORTHERN LAKE MI SW TO LOW PRESSURE IN NE MO BY EVENING WILL CONTINUE TO SPREAD AN INCREASING AREA OF RAIN AND THUNDERSTORMS INTO THE LOCAL AREA DURING THE LATER AFTERNOON. THE AREA OF PRECIPITATION WILL BE SHIFTING NE AND E ACROSS THE LOCAL AREA DURING THE EARLY TO MID EVENING AS THE SURFACE LOW CONTINUES NE ALONG THE BOUNDARY TO SOUTHERN LAKE MI PULLING A COLD FRONT ACROSS NW AND FAR NE IL BY 06Z. S TO SW WINDS SHOULD CONTINUE TO GUST AT 20-25KT THROUGH THE DAY THEN DIMINISH THIS EVENING AS THE PRESSURE GRADIENT DECREASES AS THE FRONT APPROACHES. THE COLD FRONT IS EXPECTED TO PASS ACROSS THE LOCAL AREA AROUND 07Z WITH A WIND SHIFT TO OUT OF THE W AND NW. IFR TO LIFR CONDITIONS ARE ANTICIPATED TO RETURN FOR LATER EVENING AND OVERNIGHT. TRS //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM CONFIDENCE THAT SHOWERS AND THUNDERSTORMS WILL NOT BE IN CLOSE PROXIMITY TO ORD AND MDW UNTIL LATER AFTERNOON. * HIGH CONFIDENCE IN A PERIOD OF MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LATER AFTERNOON INTO EVENING. MEDIUM CONFIDENCE IN TIMING AND CEILING/VIS DETAILS. * HIGH CONFIDENCE IN WIND TREND. * MEDIUM CONFIDENCE IN CEILING TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 300 AM CST LOW PRESSURE INCHES OVER IOWA...WILL CONTINUE TO TRACK NORTHEAST TO SOUTHERN ONTARIO BY THIS EVENING...DRAGGING A WARM FRONT NORTH ACROSS LAKE MICHIGAN...BRINGING A SURGE OF UNSEASONABLY WARM AND HUMID AIR TO THE GREAT LAKES. AN ASSOCIATED COLD FRONT TRAILS BACK TO ANOTHER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THIS SECOND LOW IS EXPECTED TO TRACK NORTHEAST ACROSS THE FAR SOUTHERN TIP OF THE LAKE LATE TONIGHT WHILE DRAGGING A STRONG COLD FRONT IN IT`S WAKE. FOLLOWING THE PASSAGE OF THIS SYSTEM...COLD HIGH PRESSURE WILL BUILD OUT OF CANADA AND SPREAD ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT. THE COMBINATION OF THE EXITING LOW...THE BUILDING HIGH AND THE INFLUX OF MUCH COOLER AIR WILL BRING NORTHWEST GALES TO THE ENTIRE LAKE BY WEDNESDAY MORNING. GALES SHOULD PERSIST OVER THE LAKE THROUGH LATE WEDNESDAY NIGHT. THE HIGH PRESSURE WILL THEN SPREAD INTO THE CENTRAL PLAINS AND MISSOURI VALLEY ON THURSDAY. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019...NOON TUESDAY TO 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
712 AM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 538 AM CST A COUPLE OF LATE THOUGHTS ON THE SEVERE WEATHER POTENTIAL LATER THIS AFTERNOON. SUBTLE SHORTWAVE IN THE SOUTHWEST FLOW IS BECOMING A BIT MORE APPARENT THIS MORNING OVER EASTERN IOWA/NORTHERN MO WITH AN INCREASE IN SCTD CONVECTION ASSOCIATED WITH THIS FEATURE. AS THIS WAVE MOVES THROUGH THIS MORNING WOULD ANTICIPATE AN INCREASE IN THE COVERAGE OF SHOWERS AND STORMS WITH EXTRAPOLATION HAVING THIS WAVE OUT OF OUR EASTERN CWA BY 15-16Z. IN THE WAKE OF THIS WEAK WAVE COULD SEE A BIT OF A LULL IN CONVECTION AND MAYBE A THINNING OF CLOUD COVER AND SOME FILTERED SUNSHINE OR AT LEAST WEAK HEATING. AS ALLUDED TO IN THE EARLIER AFD...LAPSE RATES ARE WEAK AND NOT EXPECTED TO IMPROVE MUCH TODAY. WHILE MODELS ARE FORECAST LITTLE TO NO SURFACE BASED CAPE TODAY...THEY ARE ALSO LIKELY UNDER-DOING SURFACE TEMPS BY HOLDING READINGS IN THE UPPER 50S ALL AFTERNOON. ASSUMING FORECAST HIGHS IN THE MID 60S ARE ACHIEVED THEN A FEW HUNDRED JOULES OF SBCAPE COULD BE REALIZED THIS AFTERNOON AHEAD OF THE MORE VIGOROUS SHORT WHICH IS EXPECTED TO IGNITE CONVECTION JUST TO OUR WEST THIS AFTERNOON. ASSUMING WEAK SURFACE BASED INSTABILITY DOES INDEED MATERIALIZE...THEN LOW AND DEEP LAYER SHEAR WOULD BE EXCEPTIONALLY SUPPORTIVE OF SEVERE THUNDERSTORMS WITH A WIND DAMAGE AND POTENTIALLY A LOW END TORNADO THREAT. THE SEVERE RISK TODAY IS CERTAINLY A VERY CONDITIONAL ONE BASED LARGELY ON WHETHER SOME WEAK DESTABILIZATION CAN OCCUR AND ALSO THAT FORCING CAN HELP COMPENSATE FOR THE WEAK INSTABILITY TO ALLOW FOR UPRIGHT DRAFTS THAT ARE NOT SHEARED APART. WHILE THE SEVERE RISK THIS AFTERNOON AND EVENING DOES NOT APPEAR HUGE AT THIS TIME...THE DIFFERENCE BETWEEN NOTHING AND TORNADOES IS ONLY A FEW HUNDRED JOULES OF CAPE AND THE RIGHT STORM MODE...BOTH OF WHICH ARE VERY DIFFICULT TO PREDICT BEYOND THE VERY NEAR TERM. WANTED TO ADD THIS SHORT ADDITION TO THE AFD BECAUSE I FEARED I MAY HAVE UNINTENTIONALLY DOWNPLAYED THE SEVERE THREAT A BIT TOO MUCH IN THE INITIAL MORNING AFD. IZZI && .DISCUSSION... 352 AM CST ...RECORD SHATTERING WARMTH LIKELY TODAY WITH HEAVY AND POTENTIALLY FLOODING RAINS EXPECTED LATER TODAY AND TONIGHT... THE MOTHER OF ALL WARM FRONTS IS CHARGING NORTH THROUGH THE AREA AT THIS TIME...WITH TEMPERATURES SOARING RECORD OR NEAR RECORD LEVELS IN THE MIDDLE OF THE NIGHT BEHIND THIS WARM FRONT. EQUALLY AS IMPRESSIVE IS THE MOISTURE CONTENT OF THE AIR MASS SPREADING NORTH INTO THE AREA WITH DEW POINTS CLIMBING INTO THE MID TO UPPER 50S...WHICH IN MANY CASES EXCEED DAILY RECORD HIGH TEMPERATURES. HIGH TEMP FORECAST FOR TODAY IS TRICKY AS MOST AREAS WILL BE NEAR 60F AT SUNRISE...THOUGH THERE WILL LIKELY BE SCTD SHOWERS AND THUNDERSTORMS TODAY ALSO EXPECT MANY DRY HOURS WHICH COULD EASILY ALLOW FOR AT LEAST A 4F+ RISE IN TEMPS WHICH PUTS HIGHS RIVALING ALL TIME RECORDS FOR THE MONTH OF JANUARY...WITH ANY BREAKS FOR SUNSHINE ONLY INCREASING THE CHANCE FOR AN ALL TIME RECORD. THE AIR MASS MOVING IN PRODUCED MID TO UPPER 70S OVER MO AND SW IL MONDAY AFTERNOON...SO NOT TERRIBLY FAR FETCHED TO FORECAST MID 60S UP HERE EVEN WITH WIDELY SCTD CONVECTION AROUND. PRECIPITATION-WISE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT JUST ABOUT ANY POINT IN TIME TODAY AS SUBTLE AND INDISTINGUISHABLE DISTURBANCES IN THE SW FLOW COULD KICK OFF CONVECTION. HOWEVER...WOULD EXPECT MAJORITY OF THE DAY TO BE DRY IN MOST AREAS UNTIL THE MORE SIGNIFICANT SHORTWAVE APPROACHES WESTERN CWA LATE THIS AFTERNOON WITH MORE WIDESPREAD AND VIGOROUS DEVELOPMENT OF SHOWERS AND THUNDERSTORMS UPSTREAM MOVING INTO THE CWA LATER THIS AFTERNOON. CERTAINLY WITH DEW POINTS NEAR 60F IN JANUARY AND SEASONABLY EXTREME SHEAR AM RELUCTANT TO DISCOUNT THE SEVERE WEATHER THREAT...THOUGH THE VERY MOIST ENVIRONMENT SHOULD FEATURE RATHER MODEST/WEAK LAPSE RATES...SO UNLESS WE GET SOME SUNSHINE AND BONUS HEATING WOULD GENERALLY THINK THAT INSTABILITY WILL BE TOO MEAGER FOR THERE TO BE A SIGNIFICANT SEVERE THREAT. HOWEVER...MUCH LIKE JAN 2008...SHEAR IS EXTREME SO IF WE DO REALIZE ANY APPRECIABLE INSTABILITY TODAY THEN ALL BETS WOULD BE OFF AND THERE WOULD BE A DMG WIND AND POSSIBLY EVEN A TORNADO THREAT. THE SEVERE THREAT LOOKS VERY CONDITIONAL...HOWEVER THE HEAVY RAIN THREAT LOOKS QUITE HIGH. PRETTY MUCH ANY VARIABLE YOU COULD LOOK AT TO DIAGNOSE A COLD SEASON HEAVY RAIN THREAT IS NEAR OR EXCEEDING RECORD LEVELS. PWATS ARE FORECAST TO REACH RECORD LEVELS OVER 1.3 INCHES BY THIS EVENING...WHICH IS OVER 300% OF NORMAL AND COULD EVEN APPROACH 400% OF NORMAL. LOW/MID LEVEL FLOW WILL BACK AHEAD OF THE APPROACHING TROUGH AS IT BECOMING MORE NEUTRALLY TILTED...WHICH SHOULD RESULT IN LONGER RESIDENCE TIME OF THE LARGE BAND OF RAIN AND CONVECTION IN THE WARM CONVEYOR BELT AS FLOW ALOFT BECOMES MORE ALIGNED WITH THE LOW LEVEL FRONTAL BOUNDARY. HPC`S STANDARDIZED ANOMALIES PAGE SHOWS 850MB MOISTURE TRANSPORT VALUES EXCEEDING 6 STANDARD DEVIATIONS ABOVE AVERAGE...OR IN OTHER WORDS NEARLY UNHEARD OF PROPORTIONS. FEEL THAT WIDESPREAD 1-2" RAINFALL TOTALS ARE LIKELY WITH 3"+ TOTALS NOT FAR FETCHED...AND WITH DEEP FROZEN GROUND THE FLOOD POTENTIAL LOOKS HIGH DESPITE BELOW AVG STREAM FLOW HEADING INTO THE EVENT. HAVE EXPAND THE FFA TO INCLUDE ENTIRE CWA AND DELAYED START TIME UNTIL TONIGHT FOR CHGO AND NW INDIANA. MODELS CONTINUE TO TREND SLOWER WITH THE MOVEMENT OF THE WHOLE UPPER TROUGH WHICH REQUIRED SOME ADJUSTMENTS TO THE GRIDS TO LINGER PRECIP LATER INTO TONIGHT AND DELAY THE ARRIVAL OF THE COLD AIR AND SUBSEQUENT CHANGE OVER OF ANY LINGERING PRECIP. THE SLOW MOVING STRONG COLD FRONT WILL DEMARK THE PATH THAT THE CONGA LINE OF SFC LOWS WILL TAKE WITH 00Z GUIDANCE A BIT MORE ROBUST WITH THE WAVE PROGGED TO MOVE UP THE FRONT INTO THE GREAT LAKES TOMORROW. WHILE STILL A GREAT DEAL OF VARIABILITY...GUIDANCE IS MORE BULLISH WITH DEVELOPING A DEFORMATION BAND/TROWAL WITH ACCUMULATING SNOW POTENTIAL TO THE NORTHWEST OF THE LOW TRACK. AT THIS POINT IT WOULD SEEM THE BEST THREAT OF ACCUMULATING SNOW WOULD BE OVER FAR NW IL NORTHEAST INTO WI AND MICHIGAN...BUT OUR FAR NW CWA COULD BE CLOSE ENOUGH FOR A GLANCING BLOW OF ACCUMULATING SNOW. GIVEN LOW CONFIDENCE HAVE KEPT SNOWFALL AMOUNTS MODEST FOR NOW BUT NUDGE POPS UP TO LIKELY. MID LEVEL DRY INTRUSION WOULD SEEM TO FAVOR KEEPING MEASURABLE PRECIP CHANCES LOWER OVER THE MAJORITY OF THE CWA BY THE TIME TEMPS COOL ENOUGH FOR A CHANGE OVER TO SNOW. THIS IS A VERY DYNAMIC TROUGH AND FORECAST CONFIDENCE TOMORROW IS LOW SO STAY TUNED... PROGRESSIVELY COLDER AIR FILTERS INTO THE REGION WITH FALLING TEMPS WEDNESDAY AND WEDNESDAY NIGHT. LACK OF SNOW COVER AND LINGERING CLOUDS/WINDS SHOULD KEEP TEMPS A BIT MORE MODERATE THAN WHAT AN AIR MASS OF THIS MAGNITUDE WOULD NORMALLY PRODUCE. IT WILL STILL BE A MAJOR SHOCK TO THE SYSTEM GOING FROM TEMPS NOT FAR FROM 70 TO NEAR 0 OVER NW COUNTIES IN A 48 HOUR PERIOD. CLIPPER STILL LOOKS TO BE IN THE NEIGHBORHOOD FRIDAY NIGHT INTO SATURDAY AND COULD LAY DOWN A SWATH OF ACCUMULATING SNOW SOMEWHERE IN THE MIDWEST...BUT FAR TOO FAR OUT TO PIN POINT A TRACK YET. MODERATING TEMPS ARE EXPECTED LATER INTO THE WEEKEND INTO NEXT WEEK THOUGH NOTHING LIKE WHAT WE`LL EXPERIENCE TODAY. IZZI && .CLIMATE... 330 AM CST THE FOLLOWING RECORDS COULD BE IN JEOPARDY WITH THE UPCOMING WARM SPELL TUESDAY... JANUARY 29 ALL TIME JANUARY HIGH WARM LOW RECORD HIGH ROCKFORD 55 (1914) 35 (1989) 63 (1/8/2008, 1/31/1989) CHICAGO 59 (1914) 38 (1924) 67 (1/25/1950) IZZI && .AVIATION... .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * MVFR CEILINGS TODAY. * A CHANCE OF SHOWERS AND THUNDERSTORMS THOUGH MID AFTERNOON. * WIDESPREAD RAIN AND SCATTERED THUNDERSTORMS LATER AFTERNOON THROUGH EVENING. * SOUTH TO SOUTHWEST WINDS GUST UP TO 25KT DURING THE DAY. * WINDS SHIFT TO WEST AND NORTHWEST LATE TONIGHT AS A COLD FRONT MOVES EAST ACROSS THE AREA. * RETURN OF LIFR CONDITIONS TONIGHT...MAINLY DUE TO LOW CEILINGS. TRS //DISCUSSION...UPDATED 12Z ANOTHER SHORT WAVE IS QUICKLY LIFTING NE FROM E CENTRAL IA AND WILL BE PASSING OVER NW AND N CENTRAL IL AND THEN ON TO S CENTRAL WI BY 15Z. THIS FEATURE WAS CONTINUING TO DEVELOP AND MAINTAIN SHOWERS AND THUNDERSTORMS...THAT ARE EXPECTED TO MOVE NE AND OUT OF NW AND N CENTRAL IL DURING THE EARLY MORNING. ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED AS STRONG SSW-SW FLOW IN THE LOWER AND MID LEVELS CONTINUES TO RESULT IN ISENTROPIC UPGLIDE. HOWEVER...THEY ARE EXPECTED TO BE MAINLY ACROSS SE AND E CENTRAL IA...NW IL AND N CENTRAL IL...AND SW AND S CENTRAL WI AS THIS IS WHERE THE AXIS OF GREATEST INSTABILITY IS LOCATED. FORECAST REFLECTIVITY FROM THE 08Z RUN OF THE HRRR HAD A GOOD DEPICTION OF WHERE MAIN ACTIVITY WAS OCCURRING OVER THE LAST FEW HOURS. LOOP OF REFLECTIVITY KEEPS THE TERMINALS MAINLY DRY THROUGH MUCH OF THE DAY WITH A SW-NE BAND OF RAIN AND THUNDERSTORMS AROUND 75 MILES W THROUGH N OF THE CHICAGO AREA AND ANOTHER BAND FORM 70 MILES SE TO 150 MILES SW OF ORD AND MDW. THE WARM FRONT PUSHED N TO THE WI BORDER AT 12Z. THIS RESULTED IN A WIND SHIFT TO OUT OF THE S-SSW AND A RAPID CLEARING OUT OF THE FOG THAT BLANKED THE AREA LAST EVENING AND INTO THE LATE OVERNIGHT HOURS. THE WIDESPREAD LIFR CEILINGS HAVE ALSO IMPROVED BUT NOT AS QUICKLY AS ARE CURRENTLY MAINLY MVFR. CEILINGS WILL RISE A BIT MORE TO HIGHER END MVFR BY LATE MORNING. THERE MAY BE SOME PERIODS OF VFR AS HOLES IN THE STRATOCU MOVE ACROSS THE AREA. A MID LEVEL TROUGH CONTINUES TO PROGRESS EASTWARD TODAY WITH ITS AXIS REACHING A N CENTRAL MN TO TX PANHANDLE LINE BY 00Z...AND A NE MN TO CENTRAL OK LINE BY 06Z. ANOTHER SHORT WAVE WAS CURRENTLY LIFTING NE FROM OK AND IS PROGGED TO REACH IA AND MO BY 00Z. INCREASING LIFT AHEAD OF THE TROUGH AXIS ALONG WITH LOW LEVEL CONVERGENCE ALONG AND S OF A SLOWLY ADVANCING COLD FRONT AS THE ASSOCIATED SURFACE LOW RIDES NE ALONG THE BOUNDARY PROGGED TO BE FROM NORTHERN LAKE MI SW TO LOW PRESSURE IN NE MO BY EVENING WILL CONTINUE TO SPREAD AN INCREASING AREA OF RAIN AND THUNDERSTORMS INTO THE LOCAL AREA DURING THE LATER AFTERNOON. THE AREA OF PRECIPITATION WILL BE SHIFTING NE AND E ACROSS THE LOCAL AREA DURING THE EARLY TO MID EVENING AS THE SURFACE LOW CONTINUES NE ALONG THE BOUNDARY TO SOUTHERN LAKE MI PULLING A COLD FRONT ACROSS NW AND FAR NE IL BY 06Z. S TO SW WINDS SHOULD CONTINUE TO GUST AT 20-25KT THROUGH THE DAY THEN DIMINISH THIS EVENING AS THE PRESSURE GRADIENT DECREASES AS THE FRONT APPROACHES. THE COLD FRONT IS EXPECTED TO PASS ACROSS THE LOCAL AREA AROUND 07Z WITH A WIND SHIFT TO OUT OF THE W AND NW. IFR TO LIFR CONDITIONS ARE ANTICIPATED TO RETURN FOR LATER EVENING AND OVERNIGHT. TRS //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM CONFIDENCE IN CIG/VSBY TRENDS. * MEDIUM CONFIDENCE SCATTERED SHOWERS AND THUNDERSTORMS WILL NOT BE IN CLOSE PROXIMITY OF THE CHI TERMINALS UNTIL LATER AFTERNOON. * HIGH CONFIDENCE IN A PERIOD OF RA/+RA WITH EMBEDDED TS LATE AFTERNOON INTO LATER EVENING. * MEDIUM CONFIDENCE IN TIMING OF ARRIVAL OF WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS. TRS //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT...VFR. THURSDAY...VFR. FRIDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS AT NIGHT. SATURDAY...CHANCE OF ACCUMULATING SNOW AND MVFR/IFR CONDITIONS DURING THE DAY. SUNDAY...VFR. MONDAY...VFR. TRS && .MARINE... 300 AM CST LOW PRESSURE INCHES OVER IOWA...WILL CONTINUE TO TRACK NORTHEAST TO SOUTHERN ONTARIO BY THIS EVENING...DRAGGING A WARM FRONT NORTH ACROSS LAKE MICHIGAN...BRINGING A SURGE OF UNSEASONABLY WARM AND HUMID AIR TO THE GREAT LAKES. AN ASSOCIATED COLD FRONT TRAILS BACK TO ANOTHER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THIS SECOND LOW IS EXPECTED TO TRACK NORTHEAST ACROSS THE FAR SOUTHERN TIP OF THE LAKE LATE TONIGHT WHILE DRAGGING A STRONG COLD FRONT IN IT`S WAKE. FOLLOWING THE PASSAGE OF THIS SYSTEM...COLD HIGH PRESSURE WILL BUILD OUT OF CANADA AND SPREAD ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT. THE COMBINATION OF THE EXITING LOW...THE BUILDING HIGH AND THE INFLUX OF MUCH COOLER AIR WILL BRING NORTHWEST GALES TO THE ENTIRE LAKE BY WEDNESDAY MORNING. GALES SHOULD PERSIST OVER THE LAKE THROUGH LATE WEDNESDAY NIGHT. THE HIGH PRESSURE WILL THEN SPREAD INTO THE CENTRAL PLAINS AND MISSOURI VALLEY ON THURSDAY. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019...NOON TUESDAY TO 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...6 PM TUESDAY TO 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019...6 PM TUESDAY TO 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 3 AM THURSDAY. DENSE FOG ADVISORY...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 9 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
341 PM EST TUE JAN 29 2013 .UPDATE... THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 337 PM EST TUE JAN 29 2013 NUMEROUS WEATHER HAZARDS WILL ACCOMPANY AN EXTREMELY POTENT SYSTEM IMPACTING THE REGION THROUGH TOMORROW. VERY UNSEASONABLY WARM AND MOIST CONDITIONS WILL BE IN PLACE THROUGH TONIGHT. AHEAD OF A STRONG COLD FRONT SWEEPING THROUGH THE REGION...THE POTENTIAL WILL EXIST FOR THUNDERSTORMS...HEAVY RAINFALL...FLOODING AND DAMAGING WINDS. POTENTIAL FOR STRONG WINDS WILL CONTINUE BEHIND THE FRONTAL BOUNDARY ON WEDNESDAY...AND FLOODING MAY LAST FOR SEVERAL DAYS OR MORE. && .NEAR TERM /TONIGHT/... ISSUED AT 337 PM EST TUE JAN 29 2013 FOCUS OF THE NEAR TERM REMAINS ON SEVERE WEATHER CHANCES AS WELL AS POSSIBLE HEAVY RAINFALL/FLOODING POSSIBILITIES TONIGHT. THE PERIOD BEGINS WITH GOOD SHORT TERM MODEL AGREEMENT AS TO THE LOCATION OF KEY FEATURES THAT MAY BRING POSSIBLE SEVERE TO PORTIONS OF THE FORECAST AREA TONIGHT. AT 00Z/WED...THE LOW PRESSURE CENTER IS PROGGED TO BE OVER CENTRAL MISSOURI...WITH ONGOING CONVECTION POSSIBLY ALREADY IN THE FORM OF A SQUALL LINE ALONG A STRONG COLD FRONT STRETCHED FROM NORTHWEST ILLINOIS...DOWN THROUGH CENTRAL MISSOURI...INTO EASTERN OKLAHOMA/WESTERN ARKANSAS. THERE DOES APPEAR TO BE SOME DIFFERENCES IN SPEED/TIMING OF THE FRONT INTO THE FORECAST AREA...WITH THE HRRR AND RAP INTO THE AREA A BIT QUICKER THE THE NAM AND GFS. PERSONAL EXPERIENCE HAS SHOWN THAT THESE COLD FRONT/SQUALL LINE FEATURES TEND TO COME IN A BIT QUICKER THAN SOMETIMES EXPECTED. THEREFORE...DECIDED TO TREND TOWARD THE HRRR/RUC SOLNS. AS WAS MENTIONED IN PREVIOUS DISCUSSIONS...DYNAMICS WILL NOT BE AN ISSUE WITH THIS SYSTEM AS THE FRONT APPROACHES. A LOW LEVEL JET AOA 80 KTS AT 850 MB IS EXPECTED TO DEVELOP OUT AHEAD OF THE FRONT THIS EVENING AND WILL TRANSLATE INTO OUR AREA TONIGHT. WITH 50 KT WINDS LOCATED APPROXIMATELY 1000-1500 FEET ABOVE THE SURFACE TONIGHT...DAMAGING WINDS MAY BECOME A REAL THREAT WITH ANY STORMS THAT ARE ABLE TO REMAIN ORGANIZED AS THEY PUSH INTO THE FORECAST AREA. ONE LIMITING FACTOR FOR CONVECTION REMAINING ORGANIZED INTO THE OVERNIGHT HOURS IS INSTABILITY. SFC-BASED CAPE LOOKS TO BE IN THE UNDER 200 J/KG RANGE...WHILE MUCAPE GIVES SLIGHTLY HIGHER VALUES OF 200-400 J/KG AS THE FRONT MOVES INTO THE AREA. WITH THE STRONG DYNAMICS AVAILABLE...WILL CONTINUE DAMAGING WINDS REFERENCE IN THE GRIDS. ALSO KEEP IN MIND THAT WITH AMPLE LOW LEVEL SHEAR...0-1 HELICITIES AOA 400-500 M2/S2...AN ISOLATED TORNADO CANNOT BE RULED OUT. THE BEST TIMING FOR SEVERE LOOKS TO START AT APPROXIMATELY 04-05Z ACROSS WESTERN PORTIONS OF THE FORECAST AREA...TO ABOUT 10-11Z OVER THE EAST. JUST ONE OTHER NOTE TO MENTION...THE HRRR ILLUSTRATES A LINE OF CONVECTION DEVELOPING OUT AHEAD OF THE MAIN SQUALL LINE. TO A LESSER EXTENT...THE RAP ALSO DEPICTS A SIMILAR SCENARIO. WHILE THIS FORECAST HAS TAKEN THIS INTO CONSIDERATION...IT COULD STILL ALLOW FOR AN EARLIER ONSET THAN FORECAST. HEAVY RAINFALL IS ALSO IN PLAY TONIGHT AS MOISTURE HAS CONTINUED TO STREAM NORTH INTO THE AREA. A PACIFIC TROPICAL PLUME OF MOISTURE HAS BEEN EVIDENT ALL DAY ON WATER VAPOR IMAGERY STREAMING NORTHWEST INTO LOWER MISSOURI/MID MISSISSIPPI/OHIO RIVER VALLEY STATES. COUPLE THAT WITH 60 DEGREE DEWPOINTS CURRENTLY ON THE SOUTHWESTERN DOORSTEP OF THE FORECAST AREA. PWATS TONIGHT AHEAD OF THE FRONT LOOK TO REACH UPWARDS OF 1.40-1.50 INCHES...YIELDING A PERCENT OF NORMAL OF AROUND 300 PERCENT. WOULD NOT BE SURPRISED TO SEE A WIDESPREAD 1 TO 1.5 INCH RAINFALL...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 337 PM EST TUE JAN 29 2013 SHORT TERM PERIOD SEES A DIFFERENT SET OF CHALLENGES. ONE OF THE INITIAL CHALLENGES WILL BE STRONG WINDS AFTER THE COLD FRONT SWEEPS THROUGH THE AREA AND A DRY SLOT APPROACHES THE FORECAST AREA DURING THE AFTERNOON HOURS. SUSTAINED WINDS AROUND 20-25 KTS...WITH THE POSSIBILITY TO TAP 40 KT WINDS FROM APPROX 850 MB AS BOUNDARY LAYER MIXES OUT. A WIND ADVISORY MAY BE NEED FOR A TIME IN THE LATE MORNING TO EARLY EVENING HOURS ON WEDNESDAY. ADDITIONALLY...SOME LIGHT SNOW SHOWERS MAY WRAP AROUND AND AFFECT MAINLY NORTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY NIGHT AS THE UPPER TROUGH FINALLY PASSES THROUGH. NOT CURRENTLY EXPECTING MUCH IN THE WAY OF ACCUMULATION. ANOTHER UPPER TROUGH AND COLD FRONT PUSHES INTO THE THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...BRINGING AN ADDITIONAL CHANCE FOR SNOW AND FALLING TEMPS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 144 PM EST TUE JAN 29 2013 .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE EXTENDED PERIOD WILL NOT BE NEARLY AS ACTIVE AS THE FIRST FEW DAYS OF THE FORECAST. FIRST OFF A SHORT WAVE TROUGH MOVING THROUGH THE GREAT LAKES REGION MAY BRING A FEW SNOW SHOWERS TO CENTRAL INDIANA AT THE BEGINNING OF THIS PERIOD. TEMPS/THICKNESS ALL LOOK COLD ENOUGH FOR PLAIN SNOW DURING THIS TIME. ATTM ACCUMULATIONS APPEAR TO BE AN INCH OR LESS. AFTER A COLD SHOT OF AIR THU AND FRIDAY...TEMPERATURES WILL GRADUALLY MODERATE TO CLIMO OVER THE WEEKEND AND INTO NEXT WEEK. SECOND HALF OF THE WEEKEND LOOKS DRY AND INTO EARLY NEXT WEEK. ENSEMBLES SHOW SOME PRECIP BY NEXT MONDAY/MONDAY NIGHT. TEMPERATURES LOOK WARM ENOUGH FOR A SNOW/RAIN MIX ACROSS A GOOD PORTION OF THE AREA. HAVE SMALL MINIMAL PRECIP CHANCES IN DURING THIS TIME. && .AVIATION /DISCUSSION FOR THE 29/21Z TAF UPDATE/... ISSUED AT 316 PM EST TUE JAN 29 2013 UPDATE... NO CHANGES. PREVIOUS DISCUSSION... AVIATION FORECAST BASICALLY LOOKS RIGHT ON TRACK WITH ONLY A FEW MINOR TWEAKS MADE. MVFR CEILINGS THROUGH EARLY EVENING...THEN IFR CEILINGS AS RA...SCATTERED THUNDERSTORMS AND WIND GUSTS TO 35 KNOTS DEVELOP LATER TONIGHT. OPTED TO REMOVE MUCH OF THE VCSH AND EVEN VCTS MENTION THIS AFTERNOON AND PUSH BACK TIMING FOR VCSH TO THIS EVENING WITH VCTS TO ARRIVE WITH MAIN PUSH AFTER MIDNIGHT, ALONG WITH MODERATE TO HEAVY RAINFALL. MODELS INDICATE NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS WITH COLD FRONT OVERNIGHT. IFR CEILINGS RAIN AND THUNDERSTORMS SHOULD SPREAD INTO KLAF AND KHUF THIS EVENING AND ELSEWHERE AFTER MIDNIGHT. SOUTHERLY WINDS WILL CONTINUE TO INCREASE TO 20 TO 30 KNOTS THIS AFTERNOON AND EVEN HIGHER WITH COLD FRONT OVERNIGHT. A LOW LEVEL JET WILL PRODUCE LOW LEVEL WIND SHEAR ONCE AGAIN OVERNIGHT WITH 60 KT AROUND 2K FT. && .IND WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY MORNING FOR INZ021-028>031-035>049-051>057-060>065-067>072. && $$ SYNOPSIS...MRD NEAR TERM...MRD SHORT TERM...MRD LONG TERM....SMF AVIATION...SMF/TDUD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
438 AM CST TUE JAN 29 2013 .SYNOPSIS... VERY...VERY ACTIVE WEATHER TODAY. THIS MORNING A SURFACE LOW IS LOCATED OVER NORTHERN IOWA NEAR KMCW AS OF 10Z...WITH A WARM FRONT DRAPED FROM IT SOUTHEAST ACROSS THE NORTHERN COUNTIES OF THE FORECAST AREA...GRADUALLY MOVING NORTH. DENSE FOG IS AFFECTING AREAS IN THE IMMEDIATE VICINITY OF THE FRONT...THUS THE DENSE FOG ADVISORY THAT CONTINUES UNTIL 6 AM. DEWPOINTS ON THE SOUTH SIDE OF THIS FRONT ARE IN THE MID 40S TO MID 50S...WITH TEMPERATURES IN THE UPPER 40S TO NEAR 60. A STRONG COLD FRONT IS DRAPED SOUTH FROM THE SURFACE LOW BACK INTO NORTHWEST MISSOURI AND INTO KANSAS...WITH STRONG WEST WINDS BEHIND IT. IN THE WARM SECTOR WE HAVE SCATTERED SHOWER AND THUNDERSTORM ACTIVITY...WHICH HAS SO FAR PRODUCED MAINLY SMALL HAIL REPORTS. ..LE.. && .SHORT TERM...TODAY... TODAY IS GOING TO BE A VERY BUSY DAY AS WELL...WITH THE COLD FRONT SLOWLY BEGINNING TO PLOW INTO THE FORECAST AREA WITH THIS VERY WARM MOIST AIRMASS IN PLACE. THIS MORNING THE WARM FRONT SHOULD PUSH NORTH OF THE FORECAST AREA FAIRLY EARLY...ALLOWING THE FOG TO DISSIPATE. THE CURRENT SHOWER AND THUNDERSTORM ACTIVITY IS JUST THE SECOND WAVE OF ACTIVITY THAT CAN BE EXPECTED TO AFFECT THE AREA WITH THIS EVENT. SCATTERED ACTIVITY WILL LIKELY CONTINUE TO MOVE ACROSS THE FORECAST AREA THIS MORNING. HOWEVER THIS AFTERNOON THE FRONT SHOULD REALLY LIGHT UP. THIS ALREADY WARM AIRMASS IS LIKELY TO DEVELOP MUCAPE VALUES OF 500-1000J/KG WITH HIGH TEMPERATURES IN THE 60S IN THE WARM SECTOR. THEN...A NICE SHORTWAVE AND EXIT REGION OF AN UPPER LEVEL JET COME ACROSS THIS NICE WARM AIRMASS...WE ARE GOING TO GET WIDESPREAD SHOWER AND THUNDERSTORM DEVELOPMENT. REFER TO THE SPC DAY 1 OUTLOOK FOR DETAILS...BUT IN THIS AREA WE ARE LOOKING AT STORMS WITH STRONG WINDS AND SMALL HAIL AS THE MAIN THREAT. THUNDERSTORMS WITH THIS ACTIVITY WILL BE TAPPING INTO VERY HIGH PRECIPITABLE WATER VALUE AIR FOR THIS TIME OF YEAR...AND HEAVY RAINFALL IS EXPECTED THIS AFTERNOON AND EVENING. SEE THE HYDRO SECTION BELOW FOR MORE INFORMATION. HAVE ALREADY MENTIONED HIGH TEMPERATURES...WHAT I HAVE FORECASTED FOR TODAY IS GOING TO BREAK RECORDS. UPSTREAM IN MISSOURI YESTERDAY HIGH TEMPS ROSE INTO THE 70S NEARLY EVERYWHERE...SO DO NOT THINK THAT HIGHS IN THE MID-UPPER 60S IS UNREASONABLE GIVEN THE AIRMASS THAT WE WILL HAVE. ..LE.. .LONG TERM...TONIGHT THROUGH NEXT SATURDAY... A VERY INTERESTING FCST TONIGHT THROUGH WEDNESDAY NIGHT WITH TEMPERATURES FALLING THROUGHOUT THE ENTIRE TIME FRAME. THE COLD FRONT WILL BE EAST OF THE MISSISSIPPI BY THIS EVENING. NUMEROUS SHOWERS/THUNDERSTORMS WILL BE SEEN AHEAD OF THE FRONT WITH HEAVY RAIN INTO THE FIRST PART OF THE EVENING. BY MID EVENING TEMPERATURES MAY HAVE FALLEN ENOUGH TO ALLOW A MIX TO DEVELOP OVER THE NORTHWEST THIRD OF THE CWFA. AS TEMPERATURES CONTINUE TO FALL THE RAIN WILL CHANGE OVER TO SNOW OVER ROUGHLY THE NORTHWEST 60 PERCENT OF THE CWFA BY SUNRISE WEDNESDAY. A MIX OR JUST RAIN WILL BE OCCURRING OVER THE FAR EAST/SOUTHEAST. ON WEDNESDAY...THE DEFORMATION ZONE ASSOCIATED WITH THE SFC LOW WILL MOVE ACROSS ROUGHLY THE NORTHWEST 40 PERCENT OF THE CWFA. THE TIME PERIOD JUST PRIOR TO DAWN AND THROUGH MID DAY WILL BE WHEN MOST OF THE SNOW ACCUMULATION OCCURS. STRONG CAA BEHIND THE DEPARTING LOW ON WEDNESDAY WILL RESULT IN A HIGH TEMPERATURE FOR THE DAYLIGHT HOURS OCCURRING JUST AFTER SUNRISE. TEMPERATURES WILL FALL FOR THE REMAINDER OF THE DAY. WINDS WILL BE QUITE STRONG WHICH WILL REDUCE VISIBILITIES IN RURAL AREAS. BY LATE WEDNESDAY AFTERNOON THE SNOW WILL SLOWLY TAPER TO FLURRIES THAT WILL END DURING THE EVENING HOURS. LATE WEDNESDAY NIGHT WILL BE DRY AS THE CANADIAN/ARCTIC HIGH BEGINS BUILDING INTO THE MIDWEST. AS FOR SNOW AMOUNTS...AREAS GENERALLY WEST OF A DUBUQUE TO WILLIAMSBURG LINE SHOULD SEE 3-4 INCHES WITH POSSIBLY A FEW 5 INCH AMOUNTS. SOUTHEAST OF THAT LINE AND UP TO A FREEPORT IL TO MEMPHIS MO LINE 2-3 INCHES ARE EXPECTED. SOUTHEAST OF A FREEPORT TO MEMPHIS LINE 1-2 INCHES ARE EXPECTED. DRY BUT COLD CONDITIONS WILL BE SEEN THURSDAY/THURS NIGHT AS THE CANADIAN/ARCTIC HIGH BUILDS INTO THE MIDWEST. FRIDAY ON... MODEL CONSENSUS HAS DRY CONDITIONS ON FRIDAY AHEAD OF AN APPROACHING CLIPPER SYSTEM. THIS SYSTEM WILL MOVE THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. THE CURRENT MODEL CONSENSUS SCHC POPS LOOKS REASONABLE AS WHERE THE CLIPPER TRACKS IS DEPENDENT UPON HOW DEEP THE LONGWAVE TROF OVER THE EASTERN CONUS BECOMES. SUNDAY THROUGH MONDAY THE MODEL CONSENSUS CURRENTLY HAS DRY CONDITIONS WITH MODERATING TEMPERATURES. HOWEVER...THERE ARE SEVERAL DISTURBANCES MOVING THROUGH IN THE FLOW ALOFT WITH YET ANOTHER CLIPPER TYPE SYSTEM. MOISTURE AVAILABILITY IS QUESTIONABLE SO THE CURRENT DRY FCST LOOKS REASONABLE FOR NOW. ..08.. && .AVIATION... /ISSUED 1142 PM CST MON JAN 28 2013/ WARM FRONT LIFTING NORTH THROUGH IOWA/ILLINOIS WILL RESULT IN VLIFR CONDITIONS IMPROVING TO VFR. PRIOR TO AND FOR AN HOUR OR TWO BEHIND THE FRONTAL PASSAGE LLWS IS LIKELY. RAP MODEL TRENDS SUGGEST NEW CONVECTION WILL DVLP THROUGH 12Z/29 WITH SOME TSRA POSSIBLE. COLD FRONT TO MOVE THROUGH EASTERN IOWA/ILLINOIS FROM 15Z/29 TO 00Z/30 BRINGING ANOTHER THREAT OF TSRA. VFR CONDITIONS WILL DETERIORATE TO MVFR FOLLOWING THE PASSAGE OF THE COLD FRONT. AFT 06Z/30 CONDITIONS WILL DETERIORATE TO IFR/LIFR WITH SN. ..08.. && .HYDROLOGY... AIRMASS THAT IS NOW IN PLACE OVER THE FORECAST AREA THIS MORNING HAS COPIOUS MOISTURE...WITH DEWPOINTS IN THE MID 50S. LAST NIGHTS UPPER AIR SOUNDINGS SHOWED THAT THE ENTIRE ATMOSPERE IS FAIRLY WELL LOADED WITH MOISTURE...WITH PRECIPITABLE WATER VALUES THAT ARE 200-300 PERCENT OF NORMAL FOR THIS TIME OF YEAR. QPF FROM THE THUNDERSTORMS ALONG AND AHEAD OF THE COLD FRONT IS LIKELY TO RANGE FROM 1 TO 2 INCHES OVER ABOUT THE SOUTHEASTERN THIRD TO HALF OF THE FORECAST AREA. CURRENT TIMING INDICATES THAT THIS WILL FALL IN THE AFTERNOON AND EVENING AS THE COLD FRONT PUSHES THROUGH THE AREA. GIVEN THIS SCENARIO...THE ROCK RIVER BASIN IS AT GREATEST RISK FOR POSSIBLE FLOODING...THOUGH THERE IS MUCH UNCERTAINTY OF HOW THE VERY LOW RIVER LEVELS DUE TO THE RECENT DROUGHT AND THE FROZEN GROUND WILL REACT ONCE THIS RAIN FALLS ON IT. AN ALMOST GREATER THREAT WILL BE FLOODING OF URBAN AREAS AND SMALL STREAMS DUE TO HEAVY RAINFALL RATES IN THE STRONGEST THUNDERSTORMS THIS AFTERNOON AND EVENING. ..LE.. && .CLIMATE... RECORD HIGHS FOR JANUARY 29... MOLINE.........57 IN 1914 CEDAR RAPIDS...53 IN 1919 DUBUQUE........54 IN 1914 BURLINGTON.....59 IN 1917 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR BENTON- BUCHANAN-DELAWARE-DUBUQUE-JACKSON-JONES-LINN. WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON FOR CEDAR-DUBUQUE-JACKSON-JEFFERSON-JOHNSON-JONES- WASHINGTON. WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY AFTERNOON FOR BENTON-BUCHANAN-DELAWARE-IOWA-KEOKUK-LINN. FLOOD WATCH FROM NOON CST TODAY THROUGH THIS EVENING FOR DES MOINES-LEE. IL...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR CARROLL- JO DAVIESS-STEPHENSON. WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON FOR JO DAVIESS. FLOOD WATCH FROM NOON CST TODAY THROUGH THIS EVENING FOR BUREAU- HANCOCK-HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-WARREN-WHITESIDE. MO...FLOOD WATCH FROM NOON CST TODAY THROUGH THIS EVENING FOR CLARK. && $$ LE/08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1142 PM CST MON JAN 28 2013 .AVIATION... WARM FRONT LIFTING NORTH THROUGH IOWA/ILLINOIS WILL RESULT IN VLIFR CONDITIONS IMPROVING TO VFR. PRIOR TO AND FOR AN HOUR OR TWO BEHIND THE FRONTAL PASSAGE LLWS IS LIKELY. RAP MODEL TRENDS SUGGEST NEW CONVECTION WILL DVLP THROUGH 12Z/29 WITH SOME TSRA POSSIBLE. COLD FRONT TO MOVE THROUGH EASTERN IOWA/ILLINOIS FROM 15Z/29 TO 00Z/30 BRINGING ANOTHER THREAT OF TSRA. VFR CONDITIONS WILL DETERIORATE TO MVFR FOLLOWING THE PASSAGE OF THE COLD FRONT. AFT 06Z/30 CONDITIONS WILL DETERIORATE TO IFR/LIFR WITH SN. ..08.. && .PREV DISCUSSION... /ISSUED 924 PM CST MON JAN 28 2013/ UPDATE... UPDATED THE NPW JUST BEFORE 9 PM TO DROP THE CLARK AND SCOTLAND COUNTIES. REPORTS FROM THAT AREA SUGGESTED VISIBILITIES WERE IMPROVING ALTHOUGH SOME PATCHY FOG WAS STILL OCCURRING. THE REST OF THE ADVISORY FOR THE SOUTHERN COUNTIES WAS EXTENDED TO 3 AM. HOWEVER...RECENT OBS FROM KBRL SHOW VSBYS THERE UP TO 3SM. IF THIS TREND CONTINUES PART OF THE ADVISORY WILL LIKELY BE DROPPED BEFORE MIDNIGHT. THUNDERSTORMS CONTINUE TO ERUPT OVER THE CENTRAL AND NORTHERN CWFA. RADAR DATA SUGGESTS THAT SOME OF THE STORMS CONTAIN SMALL HAIL BUT HAVE YET TO RECEIVE ANY REPORTS. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...DENSE FOG ADVISORY UNTIL 3 AM CST TUESDAY FOR BENTON-BUCHANAN- CEDAR-CLINTON-DELAWARE-DUBUQUE-IOWA-JACKSON-JOHNSON-JONES- KEOKUK-LINN-LOUISA-MUSCATINE-SCOTT-WASHINGTON. IL...DENSE FOG ADVISORY UNTIL 3 AM CST TUESDAY FOR BUREAU-CARROLL- HENRY IL-JO DAVIESS-MERCER-PUTNAM-ROCK ISLAND-STEPHENSON- WHITESIDE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
656 PM EST WED JAN 30 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 441 PM EST WED JAN 30 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM HUDSON BAY AND NW ONTARIO THROUGH MN/IA INTO ERN OK. THE POTENT SHORTWAVE TROUGH OVER SW WI AND ASSOCIATED DEFORMATION ZONE CONTINUED TO SUPPORT A HEAVY SNOW BAND FROM ERN WI INTO THE E HALF OF UPPER MI. LIGHTER SNOW WAS OBSERVED OVER THE WEST HALF OF UPPER MI. SNOW TOTALS OF AROUND 6 INCHES WERE OBSERVED BY 21Z FROM THE NWS MQT OFFICE TO MNM...GLADSTONE AND MANISTIQUE. A TIGHT GRADIENT BTWN THE 987 MB LOW OVER SRN LOWER MI AND ARCTIC HIGH PRES BUILDING INTO THE PLAINS HAS RESULTED IN GALES ACROSS LAKE SUPERIOR AND GUSTY N WINDS TO 30 MPH OVER MOST OF THE CWA. TONIGHT AND THURSDAY...THE HEAVY SNOW BAND WHICH CORRELATED WELL WITH NAM/RUC 700-600 MB FGEN IS EXPECTED TO SHIF QUICKLY TO THE NORTHEAST THIS EVENING LEAVING MAINLY LIGHT SNOW THAT WILL DIMINISH BTWN 00Z-03Z. HOWEVER...COLDER AIR MOVING IN ON THE STRONG N WINDS COMBINED WITH 850 MB TEMPS TO AROUND -15C WILL CONTINUE TO SUPPORT LCLY HIGHER SNOWFALL RATES N CNTRL...ESPECIALLY VCTY MARQUETTE THIS EVENING WITH CYCLONIC LOW LEVEL 340-350 WIND DIRECTION NEAR THE SHORE. FAVORABLE UPSLOPE NRLY FLOW INTO THE FAR WEST SHOULD ALSO BRING INCREASING LES INTO IWD. RADAR TRENDS AND MODELS SUGGEST ADDITIONAL SYNOPTIC SNOW POTENTIAL IN THE 1 TO 3 INCH RANGE BTWN 21Z- 03Z. HOWEVER AREAS WITH LAKE CONTRIBUTION COULD SEE ANOTHER 3 TO 6 INCHES THROUGH 12Z/THU. AS THE STRONGER SYNOPTIC FORCING WITH THE SHRTWV MOVES OUT THIS EVENING...HEADLINES ARE SET TO EXPIRE BY AROUND 03Z OVER THE S CWA. A TRANSISTION TO LAKE EFFECT SNOW WILL CONTINUE OVERNIGHT WITH FAVORABLE CONDITION PERSISTING INTO THURSDAY. ANOTHER TRAILING SHRTWV SLIDING SE INTO THE UPPER LAKES WILL MAINTAIN 850-700 MB MOISTURE AND INVERSION HEIGHTS AOA 10K FT. WITH THE WINDS BACKING SLIGHTLY TO 340-330 THE HEAVIER LES WILL CONTINUE TO FOCUS INTO THE FAR WEST AND TO AREAS EAST OF MARQUETTE. 850 MB TEMPS FALLING TO AROUND -20C MAY SHRINK THE DGZ LAYER INTO THE 1K-3K RANGE BUT STILL SHOULD BE SUFFICIENT FOR LSR VALUES CLOSE TO 25/1. ADDITIONAL SNOWFALL AMOUNTS OF 3 TO 7 INCHES ARE POSSIBLE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 441 PM EST WED JAN 30 2013 MODELS ARE IN GOOD GENERAL AGREEMENT THROUGH THE EXTENDED WITH DEEP UPPER TROUGH STARTING THE PERIOD FRI AND GRADUALLY BREAKING DOWN AND SHIFTING WEST THROUGH NEXT WED...AS AN UPPER RIDGE MOVES INTO THE WRN CONUS. GOOD NW WIND LES WILL BE ONGOING INTO THU NIGHT GIVEN NW LOW LEVEL FLOW...AMPLE MOISTURE AND 825MB INVERSION TOP TEMPS AROUND -25C. LATE THU NIGHT AND FRI...A SFC HIGH WILL MOVE S OF THE CWA WHILE A SHORTWAVE TROUGH DIVES IN FROM THE NW FORMING A MESO-LOW OVER ERN LAKE SUPERIOR LATE FRI. THIS TURNS THE NW WINDS WLY BY FRI AFTERNOON...FOCUSING LES OVER THE KEWEENAW AND FAR NE UPPER MI. PRIOR WIND SHIFT...THE BEST LES WILL BE FOCUSED OVER ONTONAGON AND GOGEBIC COUNTIES AND OVER ERN UPPER MI FROM MUNISING TO GRAND MARAIS. LES SHOULD INITIALLY WEAKEN SOME LATE THU NIGHT AS RIDGING MOVES INTO THE AREA...BUT WILL GET A BOOST FROM THE SHORTWAVE LATER ON FRIDAY. THERE IS ALREADY A LES ADVISORY FOR ONTONAGON/GOGEBIC COUNTIES THROUGH THU NIGHT...AND THAT STILL LOOKS FINE. BUT WILL LIKELY ALSO NEED HEADLINES FOR THE ERN U.P. THU NIGHT INTO FRI. THE KEWEENAW MAY ALSO NEED HEADLINES FRI INTO FRI NIGHT. WILL NOT ISSUE ANY NEW HEADLINES AT THIS POINT GIVEN HEADLINES ALREADY IN EFFECT OVER THE ERN U.P. AND SOME UNCERTAINTY AS TO THE RESIDENCE TIME AND INTENSITY OF ANY STRONGER BANDS THAT MOVE ACROSS THE KEWEENAW. THU NIGHT THROUGH FRI NIGHT LOOKS TO BE THE COLDEST PERIOD OF THE NEXT WEEK. LOWS THU NIGHT AND FRI NIGHT LOOKS TO FALL TO THE TEENS BELOW ZERO WITH WIND CHILLS TO -35F OVER PARTS OF THE INTERIOR. HIGHS ON FRI LOOK TO BE AROUND ZERO OVER THE INTERIOR W...AND IN THE LOW TEENS ABOVE ZERO E. WIND CHILL VALUES ARE CURRENTLY FORECAST TO BE IN TEENS BELOW ZERO AT THE WARMEST FRI AFTERNOON OVER THE INTERIOR W...AND IN THE SINGLE DIGITS BELOW ZERO E. WILL LIKELY NEED SOME WIND CHILL ADVISORY HEADLINES UP WHERE THERE ARE NO OTHER WINTER WX HEADLINES. MODELS IN RELATIVELY GOOD AGREEMENT WITH A CLIPPER SHORTWAVE MOVING THROUGH LATE SAT INTO EARLY SAT NIGHT...BUT ONLY MINOR SYNOPTIC SNOW ACCUMULATIONS AND INCREASED NW WIND LES ARE EXPECTED TO RESULT FROM THE SYSTEM. SFC RIDGING MOVES OVER ON SUN AHEAD OF THE NEXT...STRONGER...CLIPPER SYSTEM THAT MODEL DEPICT MOVING THROUGH. ALTHOUGH MODELS SEEM TO AGREE FAIRLY WELL ON THE OVERALL TRACK AND INTENSITY OF THE SYSTEM...THE 00Z/30 ECMWF IS 6-12 HOURS FASTER THAN THE 12Z/30 GFS. SEVERAL INCHES OF SNOW MAY RESULT AREA WIDE FROM THIS SYSTEM. MODELS THEN INDICATE...WITH GREATER UNCERTAINTY...ANOTHER CLIPPER SYSTEM MOVING THROUGH SOMETIME MIDWEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 655 PM EST WED JAN 30 2013 AT KIWD...LAKE EFFECT -SHSN WILL INCREASE TONIGHT AS COLDER AIR FLOWS INTO THE AREA AND LOW-LEVEL WINDS BECOME MORE CYCLONIC. AS A RESULT...MVFR CONDITIONS THIS EVENING SHOULD FALL TO IFR OVERNIGHT THRU MUCH OF THE DAY THU. AT KCMX...LIFR CONDITIONS HAVE ALREADY DEVELOPED AND WILL LIKELY CONTINUE THRU THE FCST PERIOD AS LAKE EFFECT -SHSN CONTINUE UNDER INCREASINGLY COLDER AIR MASS. WITH THE COLDER AIR...SNOWFLAKE SIZE WILL BE SMALL AND VERY EFFECTIVE AT KEEPING VIS LOW. AT KSAW...SYNOPTIC SNOW SHIELD WILL BE EXITING LEAVING LAKE EFFECT -SHSN LATE EVENING THRU THU. AS A RESULT... EXPECT INITIAL LIFR CONDITIONS TO IMPROVE TO IFR THIS EVENING AND TO MOSTLY MVFR OVERNIGHT THRU THU. AS IS TYPICAL FOR LAKE EFFECT SNOW...EXPECT VIS AT ALL SITES TO BE HIGHLY VARIABLE AT TIMES AS SNOW BANDS MOVE ACROSS THE AREA. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 441 PM EST WED JAN 30 2013 N TO NW GALES OF 35 TO 40 KNOTS WILL CONTINUE THROUGH MUCH OF TONIGHT...WITH A FEW GALE FORCE GUSTS TO 35 KNOTS LINGERING E THROUGH THURSDAY. LOW PRESSURE OVER LOWER MICHIGAN WILL LIFT NORTHEAST INTO ONTARIO AND QUEBEC TONIGHT. WITH PLENTY OF COLD AIR SINKING IN BEHIND THE LOW AND STRONG WINDS...HEAVY FREEZING SPRAY WILL PREVAIL THROUGH THURSDAY NIGHT...AND MAY LINGER OVER THE FAR EAST THROUGH FRIDAY NIGHT. A TROUGH WILL LINGER OVER LAKE SUPERIOR THROUGH THURSDAY...AS STRONG HIGH PRESSURE SINKS ACROSS THE PLAINS STATES. EXPECT THE HIGH PRESSURE SYSTEM TO WEAKEN SLIGHTLY OVER THE MISSISSIPPI VALLEY FRIDAY...WHILE PUSHING A RIDGE ACROSS WESTERN LAKE SUPERIOR. WEAK LOW PRESSURE WILL LINGER ACROSS EASTERN LAKE SUPERIOR THROUGH SATURDAY. ANOTHER LOW PRESSURE TROUGH WILL SINK SOUTHWARD FROM MANITOBA INTO THE UPPER GREAT LAKES SATURDAY EVENING...BEFORE MOVING INTO THE LOWER GREAT LAKES DURING THE DAY SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR MIZ010- 011. WINTER STORM WARNING UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ012>014. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ002-009. WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR MIZ005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST FRIDAY FOR LSZ265>267. GALE WARNING UNTIL 4 AM EST THURSDAY FOR LSZ264>267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162-263-264. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
443 PM EST WED JAN 30 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 441 PM EST WED JAN 30 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM HUDSON BAY AND NW ONTARIO THROUGH MN/IA INTO ERN OK. THE POTENT SHORTWAVE TROUGH OVER SW WI AND ASSOCIATED DEFORMATION ZONE CONTINUED TO SUPPORT A HEAVY SNOW BAND FROM ERN WI INTO THE E HALF OF UPPER MI. LIGHTER SNOW WAS OBSERVED OVER THE WEST HALF OF UPPER MI. SNOW TOTALS OF AROUND 6 INCHES WERE OBSERVED BY 21Z FROM THE NWS MQT OFFICE TO MNM...GLADSTONE AND MANISTIQUE. A TIGHT GRADIENT BTWN THE 987 MB LOW OVER SRN LOWER MI AND ARCTIC HIGH PRES BUILDING INTO THE PLAINS HAS RESULTED IN GALES ACROSS LAKE SUPERIOR AND GUSTY N WINDS TO 30 MPH OVER MOST OF THE CWA. TONIGHT AND THURSDAY...THE HEAVY SNOW BAND WHICH CORRELATED WELL WITH NAM/RUC 700-600 MB FGEN IS EXPECTED TO SHIF QUICKLY TO THE NORTHEAST THIS EVENING LEAVING MAINLY LIGHT SNOW THAT WILL DIMINISH BTWN 00Z-03Z. HOWEVER...COLDER AIR MOVING IN ON THE STRONG N WINDS COMBINED WITH 850 MB TEMPS TO AROUND -15C WILL CONTINUE TO SUPPORT LCLY HIGHER SNOWFALL RATES N CNTRL...ESPECIALLY VCTY MARQUETTE THIS EVENING WITH CYCLONIC LOW LEVEL 340-350 WIND DIRECTION NEAR THE SHORE. FAVORABLE UPSLOPE NRLY FLOW INTO THE FAR WEST SHOULD ALSO BRING INCREASING LES INTO IWD. RADAR TRENDS AND MODELS SUGGEST ADDITIONAL SYNOPTIC SNOW POTENTIAL IN THE 1 TO 3 INCH RANGE BTWN 21Z- 03Z. HOWEVER AREAS WITH LAKE CONTRIBUTION COULD SEE ANOTHER 3 TO 6 INCHES THROUGH 12Z/THU. AS THE STRONGER SYNOPTIC FORCING WITH THE SHRTWV MOVES OUT THIS EVENING...HEADLINES ARE SET TO EXPIRE BY AROUND 03Z OVER THE S CWA. A TRANSISTION TO LAKE EFFECT SNOW WILL CONTINUE OVERNIGHT WITH FAVORABLE CONDITION PERSISTING INTO THURSDAY. ANOTHER TRAILING SHRTWV SLIDING SE INTO THE UPPER LAKES WILL MAINTAIN 850-700 MB MOISTURE AND INVERSION HEIGHTS AOA 10K FT. WITH THE WINDS BACKING SLIGHTLY TO 340-330 THE HEAVIER LES WILL CONTINUE TO FOCUS INTO THE FAR WEST AND TO AREAS EAST OF MARQUETTE. 850 MB TEMPS FALLING TO AROUND -20C MAY SHRINK THE DGZ LAYER INTO THE 1K-3K RANGE BUT STILL SHOULD BE SUFFICIENT FOR LSR VALUES CLOSE TO 25/1. ADDITIONAL SNOWFALL AMOUNTS OF 3 TO 7 INCHES ARE POSSIBLE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 441 PM EST WED JAN 30 2013 MODELS ARE IN GOOD GENERAL AGREEMENT THROUGH THE EXTENDED WITH DEEP UPPER TROUGH STARTING THE PERIOD FRI AND GRADUALLY BREAKING DOWN AND SHIFTING WEST THROUGH NEXT WED...AS AN UPPER RIDGE MOVES INTO THE WRN CONUS. GOOD NW WIND LES WILL BE ONGOING INTO THU NIGHT GIVEN NW LOW LEVEL FLOW...AMPLE MOISTURE AND 825MB INVERSION TOP TEMPS AROUND -25C. LATE THU NIGHT AND FRI...A SFC HIGH WILL MOVE S OF THE CWA WHILE A SHORTWAVE TROUGH DIVES IN FROM THE NW FORMING A MESO-LOW OVER ERN LAKE SUPERIOR LATE FRI. THIS TURNS THE NW WINDS WLY BY FRI AFTERNOON...FOCUSING LES OVER THE KEWEENAW AND FAR NE UPPER MI. PRIOR WIND SHIFT...THE BEST LES WILL BE FOCUSED OVER ONTONAGON AND GOGEBIC COUNTIES AND OVER ERN UPPER MI FROM MUNISING TO GRAND MARAIS. LES SHOULD INITIALLY WEAKEN SOME LATE THU NIGHT AS RIDGING MOVES INTO THE AREA...BUT WILL GET A BOOST FROM THE SHORTWAVE LATER ON FRIDAY. THERE IS ALREADY A LES ADVISORY FOR ONTONAGON/GOGEBIC COUNTIES THROUGH THU NIGHT...AND THAT STILL LOOKS FINE. BUT WILL LIKELY ALSO NEED HEADLINES FOR THE ERN U.P. THU NIGHT INTO FRI. THE KEWEENAW MAY ALSO NEED HEADLINES FRI INTO FRI NIGHT. WILL NOT ISSUE ANY NEW HEADLINES AT THIS POINT GIVEN HEADLINES ALREADY IN EFFECT OVER THE ERN U.P. AND SOME UNCERTAINTY AS TO THE RESIDENCE TIME AND INTENSITY OF ANY STRONGER BANDS THAT MOVE ACROSS THE KEWEENAW. THU NIGHT THROUGH FRI NIGHT LOOKS TO BE THE COLDEST PERIOD OF THE NEXT WEEK. LOWS THU NIGHT AND FRI NIGHT LOOKS TO FALL TO THE TEENS BELOW ZERO WITH WIND CHILLS TO -35F OVER PARTS OF THE INTERIOR. HIGHS ON FRI LOOK TO BE AROUND ZERO OVER THE INTERIOR W...AND IN THE LOW TEENS ABOVE ZERO E. WIND CHILL VALUES ARE CURRENTLY FORECAST TO BE IN TEENS BELOW ZERO AT THE WARMEST FRI AFTERNOON OVER THE INTERIOR W...AND IN THE SINGLE DIGITS BELOW ZERO E. WILL LIKELY NEED SOME WIND CHILL ADVISORY HEADLINES UP WHERE THERE ARE NO OTHER WINTER WX HEADLINES. MODELS IN RELATIVELY GOOD AGREEMENT WITH A CLIPPER SHORTWAVE MOVING THROUGH LATE SAT INTO EARLY SAT NIGHT...BUT ONLY MINOR SYNOPTIC SNOW ACCUMULATIONS AND INCREASED NW WIND LES ARE EXPECTED TO RESULT FROM THE SYSTEM. SFC RIDGING MOVES OVER ON SUN AHEAD OF THE NEXT...STRONGER...CLIPPER SYSTEM THAT MODEL DEPICT MOVING THROUGH. ALTHOUGH MODELS SEEM TO AGREE FAIRLY WELL ON THE OVERALL TRACK AND INTENSITY OF THE SYSTEM...THE 00Z/30 ECMWF IS 6-12 HOURS FASTER THAN THE 12Z/30 GFS. SEVERAL INCHES OF SNOW MAY RESULT AREA WIDE FROM THIS SYSTEM. MODELS THEN INDICATE...WITH GREATER UNCERTAINTY...ANOTHER CLIPPER SYSTEM MOVING THROUGH SOMETIME MIDWEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1251 PM EST WED JAN 30 2013 A LARGE AREA OF SYNOPTIC SCALE SNOW WILL MOVE THROUGH THE REGION THIS AFTERNOON AND EVENING. NRLY FLOW WILL LEAD TO POTENTIAL FOR GREATER SNOWFALL RATES AND LOWER VSBY WITH LAKE ENHANCED SNOW AT IWD AND SAW. SO...MAINLY IFR CONDITIONS ARE EXPECTED WITH LIFR VSBY AT TIMES. SNOW WILL TRANSITION TO LAKE EFFECT SNOW TONIGHT AND CONTINUE INTO THURSDAY KEEPING MVFR CONDITIONS WITH OCNL IFR. WITH WINDS BACKING MORE TO THE NW CONDITIONS SHOULD GRADUALLY IMPROVE AT SAW LATE TONIGHT. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 441 PM EST WED JAN 30 2013 N TO NW GALES OF 35 TO 40 KNOTS WILL CONTINUE THROUGH MUCH OF TONIGHT...WITH A FEW GALE FORCE GUSTS TO 35 KNOTS LINGERING E THROUGH THURSDAY. LOW PRESSURE OVER LOWER MICHIGAN WILL LIFT NORTHEAST INTO ONTARIO AND QUEBEC TONIGHT. WITH PLENTY OF COLD AIR SINKING IN BEHIND THE LOW AND STRONG WINDS...HEAVY FREEZING SPRAY WILL PREVAIL THROUGH THURSDAY NIGHT...AND MAY LINGER OVER THE FAR EAST THROUGH FRIDAY NIGHT. A TROUGH WILL LINGER OVER LAKE SUPERIOR THROUGH THURSDAY...AS STRONG HIGH PRESSURE SINKS ACROSS THE PLAINS STATES. EXPECT THE HIGH PRESSURE SYSTEM TO WEAKEN SLIGHTLY OVER THE MISSISSIPPI VALLEY FRIDAY...WHILE PUSHING A RIDGE ACROSS WESTERN LAKE SUPERIOR. WEAK LOW PRESSURE WILL LINGER ACROSS EASTERN LAKE SUPERIOR THROUGH SATURDAY. ANOTHER LOW PRESSURE TROUGH WILL SINK SOUTHWARD FROM MANITOBA INTO THE UPPER GREAT LAKES SATURDAY EVENING...BEFORE MOVING INTO THE LOWER GREAT LAKES DURING THE DAY SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR MIZ010- 011. WINTER STORM WARNING UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ012>014. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ002-009. WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR MIZ005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST FRIDAY FOR LSZ265>267. GALE WARNING UNTIL 4 AM EST THURSDAY FOR LSZ264>267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162-263-264. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
551 PM EST TUE JAN 29 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 504 PM EST TUE JAN 29 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM NE MANITOBA THROUGH THE PLAINS INTO NEW MEXICO. WEAK SHRTWVS EMBEDDED IN THE SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES SUPPORTED AREAS OF SHRA/TSRA NEAR A SFC FRONT EXTENDING FROM NE WI THROUGH CNTRL MO AND INTO CNTRL OK. THE MAIN SHRTWV WAS REMAINED NEAR THE BASE OF THE TROUGH...MOVING TOWARD THE TX/OK PANHANDLE. PCPN HAD DIMINISHED OVER UPPER MICHIGAN WITH MAINLY SOME SCT LIGHT SHOWERS MOVING THROUGH FAR SRN UPPER MI. WEST WINDS AND SLIGHTLY DRIER AIR BEHIND A TROUGH SLIDING TO NEAR P53-ISQ HAS BROUGHT IMPROVED VISIBILITIES THROUGH THE CNTRL AND WEST CWA. ALTHOUGH THE 12Z ECMWF WAS A BIT SLOWER THAN THE 12Z GFS...THE MODELS WERE IN RELATIVELY GOOD AGREEMENT WITH REGARD TO OVERALL PCPN/SNOW POTENTIAL ACROSS THE CWA. ALTHOUGH THE 12Z NAM HAD SHIFTED THE HEAVIER QPF AXIS WELL TO THE EAST...THE 18Z RUN HAS COME BACK INTO BETTER AGREEMENT WITH THE GLOBAL MODELS. MODELS DIFFICULTY IN HANDLING THE CONVECTION AND HEAVY RAIN NEAR THE FRONT MAY ACCOUNT FOR A PORTION OF THE INCONSISTENCY AND VARIABILITY AND STILL LEADS GREATER THAN USUAL UNCERTAINTY. ALTHOUGH THERE IS MODERATE CONFIDENCE WITH THE MULTI-MODEL BLEND OF THE GFS/ECMWF/NAM/REG-GEM USED FOR QPF...TIMING OF THE HEAVIER PCPN ONSET MAY BE A BIT DELAYED GIVEN ECMWF/NAM TRENDS. THE STRONGEST DYNAMICS ARE EXPECTED TO DEVELOP BTWN 12Z-18Z/WED AS THE NM SHRTWV LIFTS TOWARD THE GREAT LAKES. A COUPLED UPPER LEVEL JET STRUCTURE AND RESULTING STRONG 800-600 MB FGEN WILL SUPPORT A PERIOD OF MODERATE TO HEAVY PCPN IN THE REGION...WITH THE BEST CHANCE FOR HEAVY SNOW OVER THE SE HALF OF UPPER MI. EXPECT A SHARP NW EDGE OF THE PCPN BAND DUE TO STRONG DESCENDING FGEN CIRCULATION BRANCH WHICH REDUCES CONFIDENCE IN PCPN AMOUNTS THROUGH CNTRL UPPER MI. QPF VALUES IN THE 0.30 TO 0.60 INCH RANGE WITH SNOW/WATER RATIO VALUES NEAR 16/1 SUPPORTS GENERALLY 4 TO 8 INCH SYNOPTIC SNOW...GREATEST OVER THE FAR S AND EAST. LAKE ENHANCED SNOW WILL GENERALLY BE LIGHT EARLY WED WITH LOW INVERSION HEIGHTS NEAR 4K FT AND 850 MB TEMPS ONLY NEAR -10C BUT BY WED AFTERNOON SNOWFALL RATES OVER N CNTRL AND FAR WEST NEAR IWD SHOULD INCREASE AS 850 MB TEMPS FALL TO NEAR -16C. ALTHOUGH UPSLOPE FLOW SHOULD ENHANCE SNOWFALL RATES...CYCLONIC 350 FLOW MAY ALSO LEAD TO GREATER AMOUNTS NEAR THE SHORE WED AFTERNOON. FCST CONFIDENCE WAS HIGH ENOUGH TO UPGRADE WATCHES TO WARNINGS OVER THE EAST HALF BUT WITH AMOUNTS ONLY IN THE 2 TO 5 INCH RANGE OVER MARQUETTE AND DICKINSON COUNTIES THROUGH WED AND PROXIMITY TO THE EDGE OF THE SYNOPTIC PCPN...AN ADVY WAS ISSUED. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 446 PM EST TUE JAN 29 2013 INITIAL PART OF THE LONG TERM FORECAST IS HIGHLY DEPENDENT ON THE TRACK OF THE SHORTWAVE RIDING UP THE UPPER TROUGH OVER THE CENTRAL CONUS AND THE ASSOCIATED LOW DEVELOPING IN NORTHERN LOWER MI AND THEN SHIFTING NORTHEAST INTO QUEBEC ON WEDNESDAY NIGHT. THE SHORT TERM DISCUSSION COVERS MUCH OF THE DETAILS WITH THIS SYSTEM AND THE MAIN FEATURE TO CAPTURE IN THE LONG TERM WITH THIS SYSTEM IS THE DIMINISHING TREND IN THE POPS/QPF OVER THE EASTERN CWA. BEHIND THIS FEATURE...EXPECT COLD AIR TO SURGE SOUTHEAST OVER THE UPPER GREAT LAKES REGION AND REMAIN INTO THE WEEKEND. THIS COLD AIR...H850 TEMPS IN THE LOW -20S CELSIUS...MOVING ACROSS THE RELATIVELY WARM LAKE SUPERIOR WATERS WILL LEAD TO PERSISTENT LAKE EFFECT. AMOUNTS AND LOCATIONS WILL LARGELY DEPEND ON WIND DIRECTION AND DEEPER MOISTURE DURING THIS PERIOD. FOR WEDNESDAY NIGHT...LAKE EFFECT WILL BE INCREASING IN INTENSITY OVER THE WEST THROUGH THE NIGHT DUE TO INCREASING COLD AIR AND DEEPER MOISTURE ARRIVING FROM THE NORTHWEST. THIS WILL PUSH INVERSION HEIGHTS TOWARDS 10KFT OVER THE WITH WESTERN AREAS AND WITH DELTA-T VALUES AROUND 23...LAKE INDUCED CAPE VALUES RISE TOWARDS 500-700 J/KG. EXPECT THE HIGHEST AMOUNTS...2-6 INCHES...IN THE NORTH-NORTHWEST WIND FAVORED LOCATIONS. OVER THE EAST...FORECAST IS A LITTLE MORE UNCERTAIN DUE TO THE SYSTEM...BUT THEY TOO SHOULD TRANSITION TO LAKE EFFECT. WITH MOISTURE HELP FROM THE SYSTEM...SNOW AMOUNTS WILL BE HIGHER THERE ESPECIALLY IN THE LOCATIONS FAVORED BY NORTH-NORTHWEST WINDS. THE HIGHEST AMOUNTS WILL LIKELY OCCUR THROUGH THE NIGHT OVER THE WESTERN PORTIONS OF ALGER COUNTY...WHERE COASTAL EFFECTS FROM NORTHERN MARQUETTE COUNTY WILL LIKELY INCREASE CONVERGENCE THERE AND THUS SNOWFALL AMOUNTS. HAVE TRENDED POPS TOWARDS THIS IDEA FOR THE WEDNESDAY NIGHT PERIOD. WITH THE COLD AIR CONTINING TO FLOW OVER THE AREA ON THURSDAY...MULTI-BAND LAKE EFFECT WILL BE AIDED BY THE INCREASED MID LEVEL MOISTURE MOVING OVER THE AREA BEHIND A SHORTWAVE DROPPING THROUGH THE UPPER/MID MISSISSIPPI VALLEY ON THURSDAY. THIS WILL LEAD TO INVERSION HEIGHTS IN THE 7-10KFT RANGE OVER THE AREA...WITH THE HIGHEST VALUES OVER THE EAST. THE MAIN DETERMINING FACTOR FOR SNOW AMOUNTS IN THE NORTHWEST WIND FAVORED LOCATIONS ON THURSDAY WILL BE WHEN THE DGZ FALLS BELOW OR TO THE BOTTOM OF THE CLOUD LAYER. THIS WILL OCCUR FIRST OVER THE WEST AND THEN OVER THE EAST LATE IN THE DAY. THIS WILL LEAD TO A TRANSITION TO LOWER SNOW RATIOS WITH THE TRANSITION TO MORE COLUMNS THAT IS USUALLY SEEN IN COLD/ARCTIC AIR MASSES. WITH THE WINDS BACKING TO MORE OF A NORTHWEST WIND DIRECTION THROUGH DAY...WOULD EXPECT THERE TO BE A COUPLE ENHANCED LOCATIONS DUE TO INCREASED CONVERGENCE. AT THIS TIME...WOULD EXPECT IT TO BE OVER GOGEBIC/ONTONAGON AND ALGER COUNTIES. HIGH PRESSURE SLIDING SOUTHEAST FROM THE DAKOTAS ON THURSDAY NIGHT WILL LEAD TO BACKING WINDS TO THE WEST OVER THE WESTERN LAKE AND WEST-NORTHWEST OVER THE EAST. THIS WILL CONTINUE INTO FRIDAY AS THE HIGH MOVES INTO THE MID MISSISSIPPI VALLEY AND LEADS TO WEST TO WEST-SOUTHWEST WINDS. THESE WINDS WILL BE AIDED BY A WEAK LOW DEVELOPING OVER EASTERN LAKE SUPERIOR. COLD AIR IS STILL IN THE LOWER -20S CELSIUS DURING THE PERIOD...SO THE LAKE EFFECT WILL BE ONGOING. BUT...WITH THE HIGH REDUCING THE MOISTURE ABOVE H850 AND INCREASING THE SUBSIDENCE INVERSION EXPECT THERE TO BE A GRADUAL DECREASE IN INTENSITY DURING THAT TIME FRAME. DEFINITELY THINK THAT THE NORTH-NORTHWEST WIND LOCATIONS WILL NEED LAKE EFFECT SNOW ADVISORIES DURING THIS WEDNESDAY NIGHT INTO THURSDAY NIGHT PERIOD. WARNINGS ARE A LITTLE MORE UNCERTAIN DUE TO THE LIMITED PERIODS OF THE BEST OMEGA WITHIN THE DGZ. OUT OF ALL OF THE LOCATIONS...WOULD THINK THAT ALGER COUNTY WOULD HAVE THE BEST OPPORTUNITY OF SEEING WARNING SNOWFALL AMOUNTS. OPTED TO GO AHEAD AND ISSUE THE LAKE EFFECT SNOW ADVISORY FOR GOGEBIC/ONTONAGON COUNTIES AND THE REST OF THE FAVORED AREAS WILL NEEDED TO BE ADDED IN THE NEXT 12-24HRS. HEADING INTO THE WEEKEND...THE COLDER AIR WILL BEGIN TO LOSE IT/S GRIP ON THE AREA AS THE UPPER TROUGH SHIFTS TO THE EAST AND AREA COMES UNDER NORTHWEST FLOW ALOFT. THESE PERIODS COME DOWN TO TIMING/LOCATING SHORTWAVES MOVING THROUGH THE FLOW AND HAVE TRIED TO FOLLOW A GENERAL CONSENSUS FOR TIMING THESE WAVES. FIRST ONE LOOKS TO MOVE THROUGH THE AREA ON SATURDAY NIGHT AND AGAIN ON SUNDAY NIGHT INTO MONDAY. BETWEEN THOSE TWO PERIODS...THERE SHOULD BE ENOUGH COLD AIR TO SUPPORT LAKE EFFECT SNOW IN AREAS FAVORED BY NORTHWEST WINDS. WITH THE COLD AIR SPILLING INTO THE AREA...A COOLING TREND IS EXPECTED FOR THE SECOND HALF OF THE WORK WEEK. FRIDAY CONTINUES TO LOOK LIKE THE COLDEST DAY OVER THE NEXT 7 DAYS...WITH HIGHS OVER THE WEST STRUGGLING TO RISE ABOVE 0 DEGREES. THIS COLD AIR WILL CAUSE WIND CHILL VALUES TO APPROACH -25 ON ON THURSDAY NIGHT INTO FRIDAY MORNING AND AGAIN FRIDAY NIGHT INTO SATURDAY MORNING OVER THE INTERIOR WEST HALF OF UPPER MICHIGAN. TEMPERATURES WILL THEN WARM BACK TO MORE NORMAL VALUES BY THE FIRST PART OF NEXT WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 551 PM EST TUE JAN 29 2013 IFR/LOW MVFR CIGS WILL PERSIST AT IWD AND CMX OVERNIGHT. LIFR CIGS WILL REMAIN AT SAW OVERNIGHT AS NRLY UPSLOPE WINDS CONTINUE. LIGHT SNOW WILL SPREAD INTO MAINLY CNTRL AND EAST UPPER MI WED MORNING WITH IFR VSBY EXPECTED AT SAW. SOME LAKE ENHANCED SNOW AT IWD SHOULD ALSO LEAD TO IFR CONDITIONS WHILE CMX IS EXPECTED TO ONLY SEE MVFR CIGS/VSBY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 504 PM EST TUE JAN 29 2013 A DEEPENING LOW PRESSURE SYSTEM MOVING THROUGH LAKE HURON WEDNESDAY AND TO THE NORTHEAST BY WEDNESDAY NIGHT WILL LIKELY BRING A PERIOD OF N TO NW GALES TO CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT INTO WEDNESDAY NIGHT. WINDS/WAVES COMBINED WITH ARCTIC AIR SETTLING OVER THE AREA WILL RESULT IN FREEZING SPRAY...POSSIBLY HEAVY AT TIMES LATE WEDNESDAY INTO FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM CST WEDNESDAY FOR MIZ011. WINTER STORM WARNING FROM 1 AM EST /MIDNIGHT CST/ TO 10 PM EST /9 PM CST/ WEDNESDAY FOR MIZ012>014. WINTER STORM WARNING FROM 4 AM WEDNESDAY TO 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE EFFECT SNOW ADVISORY FROM 7 AM EST /6 AM CST/ WEDNESDAY TO 7 AM EST /6 AM CST/ FRIDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR MIZ005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY FOR LSZ265>267. GALE WARNING FROM 10 AM WEDNESDAY TO 4 AM EST THURSDAY FOR LSZ267. GALE WARNING FROM 5 AM WEDNESDAY TO 4 AM EST THURSDAY FOR LSZ264>266. HEAVY FREEZING SPRAY WARNING FROM 1 PM EST /NOON CST/ WEDNESDAY TO 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162-263-264. GALE WARNING FROM 5 AM TO 10 PM EST WEDNESDAY FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...SRF AVIATION...07 MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
505 PM EST TUE JAN 29 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 504 PM EST TUE JAN 29 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM NE MANITOBA THROUGH THE PLAINS INTO NEW MEXICO. WEAK SHRTWVS EMBEDDED IN THE SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES SUPPORTED AREAS OF SHRA/TSRA NEAR A SFC FRONT EXTENDING FROM NE WI THROUGH CNTRL MO AND INTO CNTRL OK. THE MAIN SHRTWV WAS REMAINED NEAR THE BASE OF THE TROUGH...MOVING TOWARD THE TX/OK PANHANDLE. PCPN HAD DIMINISHED OVER UPPER MICHIGAN WITH MAINLY SOME SCT LIGHT SHOWERS MOVING THROUGH FAR SRN UPPER MI. WEST WINDS AND SLIGHTLY DRIER AIR BEHIND A TROUGH SLIDING TO NEAR P53-ISQ HAS BROUGHT IMPROVED VISIBILITIES THROUGH THE CNTRL AND WEST CWA. ALTHOUGH THE 12Z ECMWF WAS A BIT SLOWER THAN THE 12Z GFS...THE MODELS WERE IN RELATIVELY GOOD AGREEMENT WITH REGARD TO OVERALL PCPN/SNOW POTENTIAL ACROSS THE CWA. ALTHOUGH THE 12Z NAM HAD SHIFTED THE HEAVIER QPF AXIS WELL TO THE EAST...THE 18Z RUN HAS COME BACK INTO BETTER AGREEMENT WITH THE GLOBAL MODELS. MODELS DIFFICULTY IN HANDLING THE CONVECTION AND HEAVY RAIN NEAR THE FRONT MAY ACCOUNT FOR A PORTION OF THE INCONSISTENCY AND VARIABILITY AND STILL LEADS GREATER THAN USUAL UNCERTAINTY. ALTHOUGH THERE IS MODERATE CONFIDENCE WITH THE MULTI-MODEL BLEND OF THE GFS/ECMWF/NAM/REG-GEM USED FOR QPF...TIMING OF THE HEAVIER PCPN ONSET MAY BE A BIT DELAYED GIVEN ECMWF/NAM TRENDS. THE STRONGEST DYNAMICS ARE EXPECTED TO DEVELOP BTWN 12Z-18Z/WED AS THE NM SHRTWV LIFTS TOWARD THE GREAT LAKES. A COUPLED UPPER LEVEL JET STRUCTURE AND RESULTING STRONG 800-600 MB FGEN WILL SUPPORT A PERIOD OF MODERATE TO HEAVY PCPN IN THE REGION...WITH THE BEST CHANCE FOR HEAVY SNOW OVER THE SE HALF OF UPPER MI. EXPECT A SHARP NW EDGE OF THE PCPN BAND DUE TO STRONG DESCENDING FGEN CIRCULATION BRANCH WHICH REDUCES CONFIDENCE IN PCPN AMOUNTS THROUGH CNTRL UPPER MI. QPF VALUES IN THE 0.30 TO 0.60 INCH RANGE WITH SNOW/WATER RATIO VALUES NEAR 16/1 SUPPORTS GENERALLY 4 TO 8 INCH SYNOPTIC SNOW...GREATEST OVER THE FAR S AND EAST. LAKE ENHANCED SNOW WILL GENERALLY BE LIGHT EARLY WED WITH LOW INVERSION HEIGHTS NEAR 4K FT AND 850 MB TEMPS ONLY NEAR -10C BUT BY WED AFTERNOON SNOWFALL RATES OVER N CNTRL AND FAR WEST NEAR IWD SHOULD INCREASE AS 850 MB TEMPS FALL TO NEAR -16C. ALTHOUGH UPSLOPE FLOW SHOULD ENHANCE SNOWFALL RATES...CYCLONIC 350 FLOW MAY ALSO LEAD TO GREATER AMOUNTS NEAR THE SHORE WED AFTERNOON. FCST CONFIDENCE WAS HIGH ENOUGH TO UPGRADE WATCHES TO WARNINGS OVER THE EAST HALF BUT WITH AMOUNTS ONLY IN THE 2 TO 5 INCH RANGE OVER MARQUETTE AND DICKINSON COUNTIES THROUGH WED AND PROXIMITY TO THE EDGE OF THE SYNOPTIC PCPN...AN ADVY WAS ISSUED. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 446 PM EST TUE JAN 29 2013 INITIAL PART OF THE LONG TERM FORECAST IS HIGHLY DEPENDENT ON THE TRACK OF THE SHORTWAVE RIDING UP THE UPPER TROUGH OVER THE CENTRAL CONUS AND THE ASSOCIATED LOW DEVELOPING IN NORTHERN LOWER MI AND THEN SHIFTING NORTHEAST INTO QUEBEC ON WEDNESDAY NIGHT. THE SHORT TERM DISCUSSION COVERS MUCH OF THE DETAILS WITH THIS SYSTEM AND THE MAIN FEATURE TO CAPTURE IN THE LONG TERM WITH THIS SYSTEM IS THE DIMINISHING TREND IN THE POPS/QPF OVER THE EASTERN CWA. BEHIND THIS FEATURE...EXPECT COLD AIR TO SURGE SOUTHEAST OVER THE UPPER GREAT LAKES REGION AND REMAIN INTO THE WEEKEND. THIS COLD AIR...H850 TEMPS IN THE LOW -20S CELSIUS...MOVING ACROSS THE RELATIVELY WARM LAKE SUPERIOR WATERS WILL LEAD TO PERSISTENT LAKE EFFECT. AMOUNTS AND LOCATIONS WILL LARGELY DEPEND ON WIND DIRECTION AND DEEPER MOISTURE DURING THIS PERIOD. FOR WEDNESDAY NIGHT...LAKE EFFECT WILL BE INCREASING IN INTENSITY OVER THE WEST THROUGH THE NIGHT DUE TO INCREASING COLD AIR AND DEEPER MOISTURE ARRIVING FROM THE NORTHWEST. THIS WILL PUSH INVERSION HEIGHTS TOWARDS 10KFT OVER THE WITH WESTERN AREAS AND WITH DELTA-T VALUES AROUND 23...LAKE INDUCED CAPE VALUES RISE TOWARDS 500-700 J/KG. EXPECT THE HIGHEST AMOUNTS...2-6 INCHES...IN THE NORTH-NORTHWEST WIND FAVORED LOCATIONS. OVER THE EAST...FORECAST IS A LITTLE MORE UNCERTAIN DUE TO THE SYSTEM...BUT THEY TOO SHOULD TRANSITION TO LAKE EFFECT. WITH MOISTURE HELP FROM THE SYSTEM...SNOW AMOUNTS WILL BE HIGHER THERE ESPECIALLY IN THE LOCATIONS FAVORED BY NORTH-NORTHWEST WINDS. THE HIGHEST AMOUNTS WILL LIKELY OCCUR THROUGH THE NIGHT OVER THE WESTERN PORTIONS OF ALGER COUNTY...WHERE COASTAL EFFECTS FROM NORTHERN MARQUETTE COUNTY WILL LIKELY INCREASE CONVERGENCE THERE AND THUS SNOWFALL AMOUNTS. HAVE TRENDED POPS TOWARDS THIS IDEA FOR THE WEDNESDAY NIGHT PERIOD. WITH THE COLD AIR CONTINING TO FLOW OVER THE AREA ON THURSDAY...MULTI-BAND LAKE EFFECT WILL BE AIDED BY THE INCREASED MID LEVEL MOISTURE MOVING OVER THE AREA BEHIND A SHORTWAVE DROPPING THROUGH THE UPPER/MID MISSISSIPPI VALLEY ON THURSDAY. THIS WILL LEAD TO INVERSION HEIGHTS IN THE 7-10KFT RANGE OVER THE AREA...WITH THE HIGHEST VALUES OVER THE EAST. THE MAIN DETERMINING FACTOR FOR SNOW AMOUNTS IN THE NORTHWEST WIND FAVORED LOCATIONS ON THURSDAY WILL BE WHEN THE DGZ FALLS BELOW OR TO THE BOTTOM OF THE CLOUD LAYER. THIS WILL OCCUR FIRST OVER THE WEST AND THEN OVER THE EAST LATE IN THE DAY. THIS WILL LEAD TO A TRANSITION TO LOWER SNOW RATIOS WITH THE TRANSITION TO MORE COLUMNS THAT IS USUALLY SEEN IN COLD/ARCTIC AIR MASSES. WITH THE WINDS BACKING TO MORE OF A NORTHWEST WIND DIRECTION THROUGH DAY...WOULD EXPECT THERE TO BE A COUPLE ENHANCED LOCATIONS DUE TO INCREASED CONVERGENCE. AT THIS TIME...WOULD EXPECT IT TO BE OVER GOGEBIC/ONTONAGON AND ALGER COUNTIES. HIGH PRESSURE SLIDING SOUTHEAST FROM THE DAKOTAS ON THURSDAY NIGHT WILL LEAD TO BACKING WINDS TO THE WEST OVER THE WESTERN LAKE AND WEST-NORTHWEST OVER THE EAST. THIS WILL CONTINUE INTO FRIDAY AS THE HIGH MOVES INTO THE MID MISSISSIPPI VALLEY AND LEADS TO WEST TO WEST-SOUTHWEST WINDS. THESE WINDS WILL BE AIDED BY A WEAK LOW DEVELOPING OVER EASTERN LAKE SUPERIOR. COLD AIR IS STILL IN THE LOWER -20S CELSIUS DURING THE PERIOD...SO THE LAKE EFFECT WILL BE ONGOING. BUT...WITH THE HIGH REDUCING THE MOISTURE ABOVE H850 AND INCREASING THE SUBSIDENCE INVERSION EXPECT THERE TO BE A GRADUAL DECREASE IN INTENSITY DURING THAT TIME FRAME. DEFINITELY THINK THAT THE NORTH-NORTHWEST WIND LOCATIONS WILL NEED LAKE EFFECT SNOW ADVISORIES DURING THIS WEDNESDAY NIGHT INTO THURSDAY NIGHT PERIOD. WARNINGS ARE A LITTLE MORE UNCERTAIN DUE TO THE LIMITED PERIODS OF THE BEST OMEGA WITHIN THE DGZ. OUT OF ALL OF THE LOCATIONS...WOULD THINK THAT ALGER COUNTY WOULD HAVE THE BEST OPPORTUNITY OF SEEING WARNING SNOWFALL AMOUNTS. OPTED TO GO AHEAD AND ISSUE THE LAKE EFFECT SNOW ADVISORY FOR GOGEBIC/ONTONAGON COUNTIES AND THE REST OF THE FAVORED AREAS WILL NEEDED TO BE ADDED IN THE NEXT 12-24HRS. HEADING INTO THE WEEKEND...THE COLDER AIR WILL BEGIN TO LOSE IT/S GRIP ON THE AREA AS THE UPPER TROUGH SHIFTS TO THE EAST AND AREA COMES UNDER NORTHWEST FLOW ALOFT. THESE PERIODS COME DOWN TO TIMING/LOCATING SHORTWAVES MOVING THROUGH THE FLOW AND HAVE TRIED TO FOLLOW A GENERAL CONSENSUS FOR TIMING THESE WAVES. FIRST ONE LOOKS TO MOVE THROUGH THE AREA ON SATURDAY NIGHT AND AGAIN ON SUNDAY NIGHT INTO MONDAY. BETWEEN THOSE TWO PERIODS...THERE SHOULD BE ENOUGH COLD AIR TO SUPPORT LAKE EFFECT SNOW IN AREAS FAVORED BY NORTHWEST WINDS. WITH THE COLD AIR SPILLING INTO THE AREA...A COOLING TREND IS EXPECTED FOR THE SECOND HALF OF THE WORK WEEK. FRIDAY CONTINUES TO LOOK LIKE THE COLDEST DAY OVER THE NEXT 7 DAYS...WITH HIGHS OVER THE WEST STRUGGLING TO RISE ABOVE 0 DEGREES. THIS COLD AIR WILL CAUSE WIND CHILL VALUES TO APPROACH -25 ON ON THURSDAY NIGHT INTO FRIDAY MORNING AND AGAIN FRIDAY NIGHT INTO SATURDAY MORNING OVER THE INTERIOR WEST HALF OF UPPER MICHIGAN. TEMPERATURES WILL THEN WARM BACK TO MORE NORMAL VALUES BY THE FIRST PART OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 139 PM EST TUE JAN 29 2013 MAINLY IFR CIGS ARE EXPECTED TO PERSIST AT CMX/IWD THIS AFTERNOON. AS WINDS VEER WEST BEHIND A TROUGH THIS AFTERNOON VSBY IS EXPECTED TO IMPROVE AT SAW EVEN THOUGH IFR CIGS WILL PERSIST. LIGHT SNOW WILL SPREAD INTO MAINLY CNTRL AND EAST UPPER MI WED MORNING WITH IFR VSBY EXPECTED AT SAW. SOME LAKE ENHANCED SNOW AT IWD SHOULD ALSO LEAD TO IFR CONDITIONS WHILE CMX IS EXPECTED TO ONLY SEE MVFR CIGS/VSBY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 504 PM EST TUE JAN 29 2013 A DEEPENING LOW PRESSURE SYSTEM MOVING THROUGH LAKE HURON WEDNESDAY AND TO THE NORTHEAST BY WEDNESDAY NIGHT WILL LIKELY BRING A PERIOD OF N TO NW GALES TO CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT INTO WEDNESDAY NIGHT. WINDS/WAVES COMBINED WITH ARCTIC AIR SETTLING OVER THE AREA WILL RESULT IN FREEZING SPRAY...POSSIBLY HEAVY AT TIMES LATE WEDNESDAY INTO FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM CST WEDNESDAY FOR MIZ011. WINTER STORM WARNING FROM 1 AM EST /MIDNIGHT CST/ TO 10 PM EST /9 PM CST/ WEDNESDAY FOR MIZ012>014. WINTER STORM WARNING FROM 4 AM WEDNESDAY TO 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE EFFECT SNOW ADVISORY FROM 7 AM EST /6 AM CST/ WEDNESDAY TO 7 AM EST /6 AM CST/ FRIDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR MIZ005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY FOR LSZ265>267. GALE WARNING FROM 10 AM WEDNESDAY TO 4 AM EST THURSDAY FOR LSZ267. GALE WARNING FROM 5 AM WEDNESDAY TO 4 AM EST THURSDAY FOR LSZ264>266. HEAVY FREEZING SPRAY WARNING FROM 1 PM EST /NOON CST/ WEDNESDAY TO 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162-263-264. GALE WARNING FROM 5 AM TO 10 PM EST WEDNESDAY FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...SRF AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
349 PM EST TUE JAN 29 2013 .SYNOPSIS... ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF FOG WILL GIVE WAY TO HEAVY RAIN TONIGHT AS LOW PRESSURE MOVES THROUGH. SOME FLOODING IS POSSIBLE. THE RAIN WILL MOVE EAST ON WEDNESDAY WITH COLDER AIR MOVING IN ALONG WITH SOME RAIN CHANGING TO SNOW. TEMPERATURES WILL CONTINUE TO FALL THROUGH FRIDAY ALONG WITH LAKE EFFECT SNOW SHOWERS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF PATCHY DENSE FOG WILL CONTINUE THIS EVENING ACROSS THE NORTHERN ZONES UNTIL THE WARM FRONT LIFTS THROUGH. COVERAGE IS VARIABLE ENOUGH TO NOT GO WITH A DENSE FOG ADVISORY BUT WILL HAVE TO MONITOR OBS NEXT FEW HOURS. FLOOD WATCH CONTINUES TONIGHT FOR ALL ZONES. MOST IF NOT ALL OF THE SNOW IS GONE ACROSS THE CENTRAL AND SOUTHERN ZONES BUT SOME SNOWMELT CONTRIBUTION REMAINS UP NORTH WHERE QPF IS EXPECTED TO BE 1 TO 2 INCHES. 12Z MODEL GUIDANCE SHIFTED NORTH WITH THE AXIS OF HEAVIEST QPF ALTHOUGH THE HRRR HAS BEEN SHOWING THE MOST CONVECTIVE...AND HEAVIER...RAINS FURTHER SOUTH AND EAST. SEE HYDRO SECTION OF FORECAST FOR SPECIFICS ON RIVER FLOOD WARNINGS. EXPECT THE HEAVIEST RAINS TO MOVE INTO WESTERN ZONES THIS EVENING THEN MARCH STEADILY ACROSS THE FORECAST AREA OVERNIGHT...DEPARTING THE EASTERN ZONES WEDNESDAY MORNING. THE DEFORMATION RAIN/SNOW ZONE SHOULD BE REACHING THE NORTHWEST FORECAST AREA WEDNESDAY MORNING. WILL HAVE TO WATCH THIS AREA FOR ACCUMULATING SNOW BY LATE WEDNESDAY MORNING INTO THE AFTERNOON. COLD AIR ARRIVES IN THE AFTERNOON WITH LAKE EFFECT KICKING IN WEDNESDAY NIGHT. EXPECT LAKE EFFECT TO PENETRATE INLAND THURSDAY AND THURSDAY NIGHT WITH FLOW GOING NORTHWEST TO WEST. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 348 PM EST TUE JAN 29 2013 THE ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT THROUGH THE WEEKEND. BOTH MODELS SHOW THE DEEP UPPER TROUGH MOVING EAST AWAY FROM THE AREA AND TAKING THE CORE OF THE COLD AIR WITH IT. THE DGZ IS ALREADY GOING TO BE VERY LOW FRIDAY AND WITH THE COLD AIR MOVING AWAY WE/LL SEE THE EASTERN EDGE OF THE LAKE EFFECT SNOW SHOWERS RETREATING TOWARD THE LAKE SHORE AND THEN DIMINISHING FRIDAY NIGHT AND SATURDAY. THE NEXT CHC FOR SNOW AFTER THAT WILL BE MONDAY WHEN A CLIPPER MOVES TOWARD NRN LWR. THE GFS TAKES A MORE SRN TRACK AND WOULD GIVE US MORE SNOW. HOWEVER...WE HAVE NOT HAD MANY CLIPPERS THAT HAVE CROSSED THE CWA THIS YEAR AND SO WE/LL LEAN MORE TOWARD THE FARTHER NORTH ECMWF. TEMPS WILL WARM FROM HIGHS IN THE MID TEENS FRIDAY TO MID 30S BY MONDAY BEFORE COOLING OFF TUESDAY AFTER THE CLIPPER DRAGS A COLD FRONT THROUGH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1252 PM EST TUE JAN 29 2013 WIDESPREAD IFR/LIFR CONDITIONS EXPECTED THROUGH THE PERIOD. WE/LL SEE CONSIDERABLE RAIN TONIGHT AHEAD OF THE ARCTIC FRONT. TSRA ALSO EXPECTED FROM AROUND SUNSET THROUGH MUCH OF THE OVERNIGHT HOURS. IT/S POSSIBLE THAT SNOW WILL MIX IN WITH THE RAIN AT KMKG MID TO LATE MORNING WEDNESDAY. && .MARINE... ISSUED AT 348 PM EST TUE JAN 29 2013 WILL HOIST A SMALL CRAFT ADVISORY FOR TONIGHT THROUGH THURSDAY MORNING. THIS MAY HAVE TO BE UPGRADED TO A GALE WARNING FOR WEDNESDAY LATER ON...BUT FOR NOW IT APPEARED MARGINAL ENOUGH TO JUST GO WITH A SCA THROUGH THE PERIOD. && .HYDROLOGY... ISSUED AT 348 PM EST TUE JAN 29 2013 SCOTTVILLE ON THE PERE MARQUETTE IS FORECAST TO FLOOD...BUT OTHER RIVER POINTS ARE CURRENTLY EXPECTED TO STAY BELOW FLOOD STAGE. WILL HAVE TO WATCH THE PROGRESSION OF RAIN AND SNOW MELT THIS EVENING AND SOME OTHER SITES MAY BE ADDED TO FLOOD WARNINGS AT SOME POINT TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ037>040-043>046-050>052-056>059-064>067- 071>074. LM...SMALL CRAFT ADVISORY FROM 1 AM WEDNESDAY TO 7 AM EST THURSDAY FOR LMZ844>849. && $$ SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...93 HYDROLOGY...OSTUNO MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1139 PM CST MON JAN 28 2013 .UPDATE... UPDATED FOR 06Z AVIATION DISCUSSION. && .PREV DISCUSSION.../ISSUED AT 413 PM CST MON JAN 28 2013/ FIRST THE HEADLINES. STARTING WITH THE HRRR/RUC THEN THE REST OF THE 12Z RUNS...MODELS BEGAN TO SHIFT HEAVY SNOW BAND FOR TONIGHT FARTHER NORTHWEST...KEEPING THE BULK OF THE SNOW NW OF THE MPX CWA. MAY STILL GET A COUPLE INCHES OF SNOW IN THE FAR NW CORNERS OF TODD...DOUGLAS...AND STEVENS COUNTIES...SO WITH THAT ALONG WITH MATCHING UP WITH WHAT NEIGHBORS WERE DOING...ISSUED A WINTER WEATHER ADVISORY FOR THOSE THREE COUNTIES. AT THE OTHER END OF THE CWA HAVE A FREEZING RAIN ADVISORY FOR NE 3 COUNTIES IN WI. NOT THRILLED WITH DOING THIS ADVISORY...BUT TO MATCH UP WITH NEIGHBORING OFFICES...INCLUDED THESE COUNTIES IN A FREEZING RAIN ADVY. EVERYWHERE ELSE...DENSE FOG IS LOOKING LIKE ALL BUT A CERTAINTY FOR TONIGHT...SO A NEW DENSE FOG ADVISORY HAS BEEN HOISTED. UPPER WAVE RESPONSIBLE FOR ALL OF THIS HEADLINE FUN IS A DEEP THROUGH THAT CAN BE SEEN ACROSS THE ERN ROCKIES THIS AFTERNOON...AND WILL SLIDE ACROSS THE CENTER OF THE CONUS THROUGH WEDNESDAY. AT THIS SFC...A 996 MB LOW AT 3 PM WAS CENTERED OVER ERN CO. FAIRLY GOOD CONSENSUS AMONGST GUIDANCE ON THIS LOW MOVING TO NEAR THE SE TIP OF MN BY TUESDAY MORNING...THEN OFF TO ERN LAKE SUPERIOR BY THE TUE AFTERNOON. SEEING AN IMPRESSIVE WARM FRONT MOVING NORTH ACROSS THE PLAINS WITH THIS LOW...WITH TEMPS IN THE LOWER 70S AND DEWPS IN THE LOWER 50S UP TO ALMOST THE IA BORDER. FOR THE WEATHER TONIGHT...LEANED MOST TOWARD THE 12Z NAM FOR TIMING PRECIP IN AND ACROSS THE AREA AS THIS IS A GOOD CONTINUATION OF WHAT THE RAP HAS BEEN SHOWING. RIGHT NOW...SEEING IMPRESSIVE FGEN BAND SETTING UP ACROSS NE SODAK INTO NW MN...AND LOOKING AT RAP H7-H6 FGEN FORECAST...SHOULD SEE AN INTENSE BAND OF SNOW SET UP FROM NEAR ABERDEEN UP TO DETROIT LAKES. WITHIN THE CENTER OF THE BAND SHOULD SEE A GOOD 4 TO 6 INCHES OF SNOW. FOR THE MPX AREA...FAR NW CORNERS OF OUR FAR NW COUNTIES SHOULD GET IN ON THE SRN FRINGE OF THIS BAND...WITH A COUPLE OF INCHES OF SNOW BEING POSSIBLE. FOR SNOW POTENTIAL IN THE WEST...WILL HAVE TO WHAT HAPPENS WITH A SECONDARY SHORT WAVE THAT SNEAKS UP WEST OF THE SFC LOW LATE TONIGHT INTO TUESDAY MORNING. THE GEM WAS THE MOST BULLISH WITH THIS WAVE...BRING A QUICK 2-3 INCHES OF SNOW TO WRN MN. DID NOT PUT MUCH STOCK IN IT...BUT NOTICING THAT TOWARD THE END OF RECENT RAP RUNS IT HAS BEEN SHOWING THIS SECONDARY BAND SNEAKING IN AS WELL...SO WILL NEED TO WATCH THIS OVERNIGHT TO SEE IF THE WINTER WEATHER ADVISORY NEEDS TO BE PULLED SOUTH. OUTSIDE OF THE NW CWA...SOUNDINGS SHOW WHATEVER HAPPENING TONIGHT TO BE DRIZZLE OR LIGHT RAIN...WITH ATMO ABOVE ABOUT H8 BEING DRY... AND LITTLE OR NO SATURATION BEING SEEN IN THE DENDRITIC GROWTH ZONE. SHOULD SEE DZ/RA RAPIDLY SPREAD NORTH AFTER 00Z AS STRONG LOW LEVEL THETA-E ADVECTION WORKS IN. AT THE NOSE OF THE LLJ...THE RAP IS EVEN INDICATING SOME THUNDER BEING POSSIBLE IN THE EAU AREA AROUND MIDNIGHT AS BEST LIS DROP TO AROUND -1. 18Z HRRR REFLECTIVITY FORECAST LOOKS CONVECTIVE IN THIS AREA AS WELL. OF COURSE WITH ALL OF THIS PRECIP THE KEY WILL BE SFC TEMPS. THE ENTIRE CWA CURRENTLY SITS BETWEEN 32 AND 36 AND WITH CONTINUED SOUTHEAST FLOW THROUGH THE NIGHT...DO NOT EXPECT THESE TO CHANGE MUCH...IN FACT...TEMPERATURES MAY CONTINUE TO RISE RIGHT THROUGH THE NIGHT ACROSS THE SE CWA. BECAUSE OF THESE MILD TEMPERATURES...WAS NOT TOO INCLINED TO ISSUE A FREEZING RAIN ADVY WITH IT BEING QUESTIONABLE IF TEMPS FALL BELOW FREEZING. IN ADDITION...WITH P-TYPE MAINLY BEING DZ...NOT EXPECTING MANY IMPACTS WITH DZ AND TEMPS IN THE 30S WITH ALREADY WET SFCS IN PLACE DUE TO MELTING TODAY. MAKE IT DRY WITH TEMPS IN THE 20S...AND IT WOULD BE A DIFFERENT STORY...BUT THAT IS NOT WHAT WE ARE DEALING WITH. WHERE THE HIGHEST POTENTIAL FOR MEANINGFUL FZRA EXISTS WOULD BE IN THE FAR NE CWA...WHERE THERE WILL BE THE POTENTIAL FOR RAIN THIS EVENING ON THE NOSE OF THE LLJ. AS FOR THE FOG...THERE IS NOTHING BUT A SEA OF DENSE FOG FROM SRN MN DOWN ACROSS IA AND ERN NEB. THIS WILL ADVECT RIGHT BACK NORTH THIS EVENING...WITH WIDESPREAD FOG EXPECTED AGAIN...AS SEEN WITH THE GRIDDED LAMP...HRRR...AND WRF-NMM. FOG SHOULD IMPROVE LATE TONIGHT FROM WEST TO EAST AS AN INVERTED TROUGH/COLD FRONT WORKS ACROSS MN. FOR SIMPLICITY SAKE...RAN THE FOG ADVY THROUGH 10 AM TUESDAY MORNING EVERYWHERE...BUT CONDITIONS SHOULD IMPROVE EARLIER THAN THAT IN WRN MN. PRECIPITATION SHOULD MOSTLY COME TO AN END BY TUESDAY AFTERNOON ACROSS THE AREA AS DRY ARCTIC HIGH BEGINS BUILDING IN. STILL SOME DISAGREEMENT WITH PRECIP POTENTIAL TUESDAY NIGHT AS ANOTHER SFC LOW RIPPLES NORTH ALONG THE FRONT FROM THE TULSA AREA UP TO MID MICHIGAN. HUNG SOME CHANCE POPS BACK ACROSS ERN AREA TO ACCOUNT FOR THE OFF CHANCE THAT SOME SNOW DEVELOPS WEST OF THE LOW. NOT ALL THAT EXCITED ABOUT SNOW POTENTIAL ON THE BACK SIDE OF THIS SYSTEM TUESDAY NIGHT INTO WEDNESDAY DUE TO THE FACT THAT UPPER FLOW WILL BE NEARLY PARALLEL TO THE FRONTAL BOUNDARY. THIS WILL LIKELY KEEP A COLD CONVEYOR BELT FROM DEVELOPING TO THE NORTH AND NORTHWEST OF THE LOW AS IT WORKS UP ALONG THE FRONT...WITH MOST ACTIVITY STAYING NEAR THE FRONT...AND NOT WORKING BACK TOWARD THE EAU AREA. OF COURSE THE BIG STORY FOR WEDNESDAY THROUGH FRIDAY WILL BE THE ARRIVAL OF ANOTHER SIGNIFICANT CHUNK OF ARCTIC AIR. TEMPERATURES WILL BE NEARLY STEADY OR FALLING MUCH OF WEDNESDAY AFTERNOON...AND BY WEDNESDAY NIGHT...THE COMBO OF TEMPS FALLING TO BELOW ZERO ON 15 TO 25 MPH NW WINDS WILL BRING BACK THE NEED FOR WIND CHILL ADVISORIES FROM WEDNESDAY NIGHT RIGHT INTO FRIDAY MORNING. AFTER FRIDAY...TEMPERATURES WILL MODERATE BACK CLOSER TO AND EVEN A LITTLE ABOVE NORMAL BY THE END OF THE WEEKEND. STILL SEEING THE POTENTIAL FOR A CLIPPER FRI NIGHT/SATURDAY ON THE ECMWF/GEM...WITH A COUPLE OF INCHES OF SNOW BEING POSSIBLE ALONG AND NORTH OF I-94. && .AVIATION.../06Z TAF ISSUANCE/ IFR OR LIFR CONDITIONS STILL EXPECTED THROUGH THIS MORNING. THE MAIN FORECAST UNCERTAINTIES CONTINUE TO BE PRECIPITATION TYPE. MOST STATIONS ARE AT OR SLIGHTLY ABOVE FREEZING WHICH SHOULD CONTINUE FOR MUCH OF THE NIGHT IN THE LIGHT SOUTHEAST FLOW. NOT OVERLY CONCERNED WITH FZDZ OR FZRA DUE TO THE MOIST AIRMASS WHICH LIMITS ICE ACCRETION AT THESE MARGINAL TEMPERATURES. WITH TIME...A BAND OF SNOW IS EXPECTED TO DEVELOP ACROSS WEST CENTRAL MN AND THE BULK OF IT SHOULD REMAIN JUST WEST OF AXN. AS LOW PRESSURE TRACKS NORTHEAST INTO WISCONSIN TUESDAY MORNING...DRIER AIR WILL BEGIN TO WORK IN WITH IMPROVING CONDITIONS. THIS COULD ALSO BRING A BETTER CHANCE FOR -SN OR FZDZ FURTHER EAST. KMSP...LIFR CONDITIONS EXPECTED THROUG THIS MORNING WITH A GRADUAL IMPROVEMENT TO MVFR TUESDAY AFTERNOON. PRECIP SHOULD REMAIN IN LIQUID FORM...BUT WILL NEED TO WATCH TEMPERATURES CLOSELY FOR POTENTIAL FOR FZDZ LATE TONIGHT. BETTER CHANCE OF SUCH PRECIP WILL ARRIVE MID MORNING TUESDAY AS COLDER AND DRIER AIR BEGINS TO WORK IN FROM THE NORTH/NORTHWEST. /OUTLOOK FOR KMSP/ WED...MVFR WITH POSSIBLE --SN. WIND NW 15-20G30KT. THU...VFR WITH POSSIBLE MVFR CIGS. WIND NW 10-15G20KT. FRI...VFR WITH POSSIBLE MVFR CIGS. LGT/VRB WIND. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR ANOKA-BENTON-BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-FARIBAULT- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-MILLE LACS-MORRISON- NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE- SIBLEY-STEARNS-STEELE-SWIFT-WASECA-WASHINGTON-WATONWAN- WRIGHT-YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR DOUGLAS- STEVENS-TODD. WI...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR DUNN-EAU CLAIRE- PEPIN-PIERCE-POLK-ST. CROIX. FREEZING RAIN ADVISORY UNTIL 9 AM CST TUESDAY FOR BARRON- CHIPPEWA-RUSK. && $$ MPG/CLF
AREA FORECAST DISCUSSION
NWS HASTINGS NE
358 PM CST TUE JAN 29 2013 .SHORT TERM...TONIGHT AND WEDNESDAY. HIGHLY AMPLIFIED MEAN TROUGH IS HEADING EAST WITH THE AXIS CROSSING INTO THE HIGH PLAINS. STRONG JET AHEAD OF THIS AXIS WITH STIFF MID-LEVEL FRONTOGENETIC FORCING PREDICTED TO RAMP UP THIS EVENING. THIS IS SUPPORTED BY THE NAM...HRRR...ECMWF...AND GFS...ALL PLACING DECENT QPF AMOUNTS IN THE EAST/SOUTHEAST PART OF THE CWA AT THE VERY LEAST. THIS AGREEMENT AMONG MODELS HAS LED ME TO INCREASE CHANCES OF PRECIPITATION EVEN MORE. SOUNDINGS INDICATE THAT THIS WILL BE A SNOW EVENT AND HAVE GONE WITH ONLY SNOW AS THE PRECIPITATION TYPE...AS OPPOSED TO MENTIONING RAIN AT ONSET. THE HRRR INDICATE4D QUITE A RAMP UP IN QPF PRODUCTION BY EARLY AFTERNOON...WHICH PROMPTED ME TO GO WITH AN ADVISORY FOR MOST OF OUR EASTERN CWA. I FELT INCLINED TO DO THIS AS NORTH/NORTHWEST WIND WILL RAMP UP CONSIDERABLY TONIGHT AS THE SURFACE PRESSURE GRADIENT INCREASES. I INCREASED WIND SPEEDS A BIT MORE FROM THE PREVIOUS FORECAST FOR TONIGHT INTO WEDNESDAY. SNOW SHOULD WIND DOWN FAIRLY QUICKLY AS THE TROUGH AXIS HEADS TO THE EAST BY THE OVERNIGHT. LEFT THE SLIGHT CHANCE OF FLURRIES IN OUR NORTHEAST FOR WEDNESDAY MORNING...BUT I DID NOTICE THE NAM PULLING BACK A LITTLE ON STRATUS...WHICH USUALLY INDICATES A LACK OF FLURRY POTENTIAL...BUT CLOSE ENOUGH FOR ME TO LEAVE IN FOR NOW. WIND SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR WEDNESDAY...ALTHOUGH OUR FAR NORTH MAY FLIRT WITH IT...JUDGING BY PREDICTED MOMENTUM TRANSFER. KEPT SKY COVER GENERALLY CLOUDY...ALTHOUGH THERE COULD BE SOME BREAKS...ESPECIALLY IN THE SOUTH BY AFTERNOON. KEPT TEMPERATURES THE SAME FOR TONIGHT AND WEDNESDAY FROM PREVIOUS FORECAST AS THEY LOOKED LIKE THEY WERE RIGHT ON TARGET. .LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY. MAIN FORECAST CONCERN IN THE EXTENDED WILL BE THE TEMPERATURES. STARTING WED EVENING...THE BIG PICTURE SHOWS THE CENTRAL U.S. IN NORTHWEST FLOW AS THE UPPER TROUGH IS SLATED TO BE MOVING INTO THE MIDWEST WITH RIDGING MOVING ONTO THE PACIFIC NORTHWEST COAST. AS THE WORK WEEK ROLLS ALONG IT APPEARS WE WILL PRETTY MUCH STAY IN THIS TYPE OF FLOW WITH OVERALL RIDGING TO THE WEST AND TROUGHING EAST. WILL MOST LIKELY HAVE A FEW CLIPPER LIKE WAVES SLIDE THROUGH OUR REGION UNDER THIS TYPE OF PATTERN AND THE QUESTION IS WILL THEY BRING ANY ADDITIONAL PRECIPITATION CHANCES. BASIC ANSWER IS NO ALTHOUGH WE DO HAVE A CHANCE OF FLURRIES MENTIONED FOR WED NIGHT AND THURSDAY IN THE CURRENT FORECAST AND WILL GO AHEAD AND KEEP THEM IN GIVEN SUFFICIENT MOISTURE AND COLDER TEMPERATURES NOTED IN MODEL FORECAST SOUNDINGS. OTHERWISE WILL LEAVE THE REST OF THE FORECAST DRY ALTHOUGH SOME LIGHT PRECIPITATION NOT TOTALLY OUT OF THE QUESTION FOR FRIDAY. AS FAR AS TEMPERATURES GO...IT WILL REMAIN QUITE CHILLY WED NIGHT INTO FRIDAY MORNING AS ADDITIONAL COLD AIR SLIDES DOWN FROM THE NORTH...ALTHOUGH THE BITTER COLD AIR SHOULD REMAIN JUST NORTHEAST OF THE CWA. STOUT NORTHWEST WINDS ARE ALSO EXPECTED AGAIN FOR THURSDAY AFTERNOON AS WE SIT BETWEEN 1038 MB HIGH PRESSURE OVER MONTANA/NDAK AND LOW PRESSURE ACROSS MISSOURI AND KANSAS. FRIDAY MORNING MIGHT BE THE COLDEST DAY OF THE WEEK DEPENDING ON WHETHER HIGH PRESSURE DROPS RIGHT OVER THE TOP OF US OR SLIDES A LITTLE TO THE EAST IN WHICH CASE WE MIGHT HAVE A MORE CLOUD COVER AND LIGHT SOUTHERLY FLOW. GOING INTO THE WEEKEND HEIGHTS BEGIN TO RISE AS WESTERN RIDGE STARTS TO MOVE EAST AND AT THIS POINT APPEARS BOTH SAT AND SUNDAY SHOULD BE CLOSE TO 50 DEGREES. ANOTHER WEAK FRONT IS EXPECTED TO PUSH ACROSS SUNDAY NIGHT OR MONDAY WITH HIGH TEMPERATURES FALLING A TAD BUT STILL ABOVE SEASONAL LEVELS. && .PREV DISCUSSION... /ISSUED 1243 PM CST TUE JAN 29 2013/ AVIATION...18Z KGRI TAF. CEILINGS WILL BE TRICKY FOR THE FIRST SEVERAL HOURS OF THE FORECAST AS CEILINGS ARE HIGHLY VARIABLE EAST OF A BAND OF SNOW THAT HAS DEVELOPED WEST OF THE TERMINAL. SOME SNOW IS EXPECTED TO MOVE IN THIS EVENING WITH AN INCREASE IN WIND SPEED BEHIND A COLD FRONT. MVFR CEILINGS ARE FORECAST FOR MUCH OF THE FORECAST. VISIBILITY IS FORECAST FOR MVFR WHEN SNOW BEGINS...BUT THIS COULD BE TEMPORARILY LOWER IF A BAND OF HEAVIER SNOW SETS UP...BUT THIS IS MORE LIKELY TO OCCUR TO THE SOUTHEAST. CEILINGS SHOULD RISE TOWARD MID-MORNING WEDNESDAY...BUT WIND WILL REMAIN RATHER BRISK FROM THE NORTHWEST. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 1 AM CST WEDNESDAY FOR NEZ049-063- 064-076-077-086-087. KS...WINTER WEATHER ADVISORY UNTIL 1 AM CST WEDNESDAY FOR KSZ007. && $$ SHORT TERM/AVIATION...HEINLEIN LONG TERM...EWALD
AREA FORECAST DISCUSSION
NWS BUFFALO NY
723 PM EST WED JAN 30 2013 .SYNOPSIS... RAIN...HEAVY AT TIMES WILL FALL ACROSS THE REGION TONIGHT AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE REGION WHICH WILL SEND TEMPERATURES BACK TO SEASONAL NORMALS. AS THE COLD AIR DEEPENS ON THURSDAY...LAKE EFFECT SNOWS WILL SET UP IN THE TRADITIONAL SNOWBELTS EAST AND SOUTHEAST OF THE LAKES...THEN WILL CONTINUE THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH THURSDAY/... LOW PRESSURE ACROSS LAKE HURON WILL LIFT NORTHEAST ACROSS SOUTHERN ONTARIO TONIGHT. THIS WILL BRING A COLD FRONT ACROSS THE REGION TONIGHT...FORECAST TO ENTER FAR WESTERN NEW YORK AROUND MIDNIGHT...THEN SWEEP RAPIDLY TO THE EAST THROUGH THE EARLY MORNING HOURS. THIS WILL CAUSE AN ABRUPT DROP IN TEMPERATURES. IN ADDITION....THIS SYSTEM WILL SET UP A DEEP SOUTHERLY FLOW OUT AHEAD OF IT...WHICH WILL TRANSPORT MOISTURE FROM PENNSYLVANIA AND INTO CENTRAL NEW YORK TONIGHT. A BLEND OF RADAR AND HRRR MODEL GUIDANCE THROUGH 700 PM SHOW A SLIGHTLY LATER START TIME IN RAIN...WITH A SHARP CUT OFF ON THE WEST SIDE OF THE HEAVIER RAINS. AT THIS TIME...IT APPEARS MORE LIKELY THAT THE HEAVIEST RAINS WILL BE EAST OF THE GENESEE RIVER. THERE WILL BE NO CHANGE TO HEADLINES AT THIS TIME...BUT THERE APPEARS TO BE A DIMINISHING THREAT FOR FLOODING IN WESTERN PORTIONS OF THE FLOOD WATCH...WHILE TRENDS SUPPORT A CONTINUED RISK...ESPECIALLY EAST OF LAKE ONTARIO IN THE BLACK RIVER BASIN AND ITS TRIBUTARIES. 1. RAINFALL...AS THE UPPER LEVEL SHORTWAVE CONTINUES TO DEEPEN AN UPPER LEVEL TROUGH OVER THE CENTRAL GREAT LAKES THE COLD FRONT PASSAGE IS NOW SLIGHTLY SLOWER...ALLOWING FOR THE AXIS OF HEAVIEST RAINFALL TO NOW FALL ACROSS EASTERN PORTIONS OF THE CWA. WITH A VERY MOIST AIRMASS FOR THIS TIME OF YEAR AND THE DEEP MOISTURE ALREADY SEEN STREAMING NORTHWARD TOWARDS THE GREAT LAKES AND NEW ENGLAND REGION HEAVY RAINFALL IS LIKELY OVERNIGHT. LIFT FROM THE COLD FRONT...DIFFLUENCE IN THE UPPER LEVELS AND A NEARBY RIGHT ENTRANCE REGION OF A 150 KNOT 250 HPA JET WILL LEAD TO DEEP SYNOPTIC LIFT. THE 12Z SUITE OF THE ECMWF...GFS...NAM...AS WELL AS THE 09Z SREF MEAN DISPLAYING CLOSE TO AN INCH AND A HALF TO AS MUCH AS 2 INCHES OF RAINFALL BY 12Z TOMORROW FROM PORTIONS OF THE UPPER GENESEE VALLEY AND ACROSS THE FINGER LAKES REGION AND TOWARDS EASTERN LAKE ONTARIO REGION. LESS RAINFALL...LIKELY AROUND AN INCH OR LESS WILL FALL ACROSS THE NIAGARA FRONTIER AND FAR WESTERN SOUTHERN TIER. THE FLOODING POTENTIAL WILL BE OF SMALL CREEKS AND STREAMS AS WELL AS PONDING WATER FROM HEAVY RAINFALL OVER A SATURATED/FROZEN GROUND. THE SREF EXPERIMENTAL MODEL ENSEMBLE RIVER FORECASTS ARE MORE BULLISH WITH RIVER FLOOD POTENTIAL THAN THE GEFS AND THE NAEFS. ANY LARGER RIVER OR CREEKS THAT MAY REACH ACTION OR FLOOD STAGE MAY BE ACROSS THE UPPER GENESEE AND EASTERN LAKE ONTARIO REGION...AS SUGGESTED BY THE GEFS AND THE NAEFS...AS WELL AS WHERE THE AXIS OF HEAVY RAIN IS LIKELY. SINCE THE FLOODING CONCERNS WILL CONTINUE EVEN AFTER THE RAIN STOPS AND TEMPERATURES FALL BELOW FREEZING...HAVE ELECTED TO EXTEND THE FLOOD WATCH UNTIL 18Z THURSDAY FOR ALLEGANY COUNTY THROUGH THE FINGER LAKES AND EASTERN LAKE ONTARIO REGION. 2. STRONG WINDS...THE AFOREMENTIONED STORM SYSTEM WILL DEEPEN FROM AROUND 985MB 00Z TONIGHT TO 970MB 12Z TOMORROW MORNING JUST NORTH OF VERMONT...AND THEN BELOW 960 MB BY 00Z FRIDAY ACROSS EASTERN QUEBEC. THIS RAPID DEEPENING...COMBINED WITH 6 TO 8 MB ISALLOBARIC PRESSURE RISES WITHIN COLD AIR ADVECTION FOLLOWING THE COLD FRONT SHOULD BE ABLE TO MIX A 50 KNOT JET AT 925 HPA DOWN TO THE SURFACE. GIVEN THE STRONG AND VERY DYNAMIC NATURE OF THIS SYSTEM...ITS ASSOCIATED WIND FIELDS WILL ALSO BE QUITE STRONG. WE WILL UPGRADE THE ADVISORY TO A WARNING FOR A GOOD PORTION OF THE CWA. WIND GUSTS UP TO 60 MPH ARE LIKELY IN FAVORED AREAS ALONG THE LAKE ERIE SHORELINE INLAND ACROSS SOUTHERN LAKE ONTARIO AND THROUGH THE EASTERN LAKE ONTARIO REGION. FOR OUR INLAND COUNTIES OF WYOMING...ALLEGANY...LIVINGSTON AND ONTARIO WE WILL LEAVE A HIGH END WIND ADVISORY AS THE DEEPENING LOW MAY BE TOO FAR NORTH TO ALLOW FOR WARNING CRITERIA WINDS HERE. 3. LAKE EFFECT SNOW...FOLLOWING THE PASSAGE OF THE COLD FRONT -14C TO -16C 850 HPA AIR TEMPERATURES WILL BE CROSSING THE LAKES. AT FIRST WINDS MAY BE TO STRONG FOR GOOD FORMATION OF LAKE EFFECT SNOW BANDS WITH THE WINDS SHEARING AWAY THE LAKE BAND FORMATION. ALSO WITH THE STRONG WINDS RESIDENT TIME OVER THE LAKE BODIES WILL BE LIMITED. AS WINDS DIMINISH THROUGH THE AFTERNOON AND COLD AIR DEEPENS...AND LAKE INDUCED EQUILIBRIUM LEVELS RISE TOWARDS 7 TO 9K FEET A BAND OF SNOW SHOULD BE FORMING OFF BOTH LAKE ERIE AND LAKE ONTARIO. THE NAM...AND TO A DEGREE THE GFS HAS DEEP SYNOPTIC MOISTURE REMAINING IN THE SNOW GROWTH ZONE...WHICH WILL BE FALLING WITH THE COLD AIR ADVECTION. OFF LAKE ONTARIO...WIND FIELD CONVERGENCE OVER LAKE ONTARIO IS LEADING TO IMPRESSIVE OMEGA FIELDS BY THURSDAY AFTERNOON WHERE A BAND OF LAKE EFFECT SNOW MAY BEGIN TO PRODUCE SNOWFALL RATES UP TO 2 INCHES PER HOUR. FOLLOWING THE SURFACE LOW AND UPPER LEVEL TROUGH WINDS WILL BEGIN TO VEER THROUGH THE DAY DROPPING THE LAKE EFFECT SNOW BAND SOUTH OF JEFFERSON COUNTY. FOR THIS REASON WILL LEAVE JEFFERSON COUNTY AS A HIGH END LAKE EFFECT SNOW ADVISORY...AND HAVE WARNINGS FOR LEWIS AND OSWEGO COUNTIES WHERE THE BAND WILL LIKELY FALL LONGER. OFF LAKE ERIE...A WESTERLY FLOW OVER THE STILL OPEN WATERS OF LAKE ERIE WILL BRING MULTI BANDED STRUCTURE SNOW BANDS ACROSS THE SOUTHERN TIER. CONFIDENCE IS GREATER ACROSS CHAUTAUQUA AND CATTARAUGUS COUNTIES THAN SOUTHERN ERIE AND WYOMING COUNTIES FOR WARNING CRITERIA SNOW. WILL UPGRADE THE WATCH TO A LAKE EFFECT WARNING ACROSS THE SOUTHERN TIER...WHILE LEAVING ADVISORIES FOR SOUTHERN TIER AND WYOMING COUNTIES. 4. REGARDING TEMPERATURES...RECORDED HIGHS WERE SHATTERED ACROSS MUCH OF THE REGION TODAY WITH MORNING AND EARLY AFTERNOON HIGHS REACHING NEAR 10 DEGREES ABOVE RECORD VALUES FOR THE DATE. THE NEW RECORDS FOR TODAY... BUFFALO.....66 (PREVIOUS WAS 56 IN 1916) ROCHESTER...64 (PREVIOUS WAS 55 IN 1974) WATERTOWN...63 (PREVIOUS WAS 52 IN 1995) THESE READINGS ARE STILL SEVERAL DEGREES SHY OF THE ALLTIME MONTHLY RECORD HIGH TEMPERATURE WHICH ARE AS FOLLOWS: BUFFALO...72 IN 1950. ROCHESTER...74 IN 1950...CORRECTED WATERTOWN...66 IN 1995. THE COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT SENDING TEMPERATURES BACK TO SEASONAL NORMS...WITH MANY AREAS DOWN INTO THE UPPER 20S AND LOW 30S BY TOMORROW MORNING. WITH THE RAIN OVERNIGHT THE PROSPECTS FOR BLACK ICE WILL BE PRESENT AS WE QUICKLY COOL FURTHER INTO THE MID AND UPPER 20S BY MID MORNING. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... HEAVY LAKE EFFECT SNOWS SHOULD BE ONGOING ON A WESTERLY FLOW REGIME AT THE START OF THE PERIOD. BUFR PROFILES FROM THURSDAY NIGHT THROUGH AT LEAST THE DAYTIME HOURS OF FRIDAY CONTINUE TO LOOK RATHER IMPRESSIVE...AS A DEEP LAYERED CYCLONIC FLOW REGIME IS WELL ESTABLISHED. MOISTURE PROFILES LOOK QUITE ADEQUATE WITH SATURATION WELL UP THROUGH 10K FEET AND DEEPER AT TIMES AS A COUPLE OF REINFORCING WEAK SHORTWAVES WORK THROUGH THE MEAN WEST NORTHWEST FLOW. THE BIGGEST FACTOR THAT COULD LIMIT TOTALS WILL BE THE VEERING WINDS IN RESPONSE TO A SHORTWAVE CROSSING THE LOWER LAKES. THIS WILL TEND TO PUSH THE LAKE BANDS...ESPECIALLY ACROSS LAKE ONTARIO SOUTHWARD. THIS COULD BRING THE PRIME LAKE EFFECT FOCUS ALONG THE SOUTH SHORE OF LAKE ONTARIO...WHICH COULD BRING AT LEAST ADVISORY OR GREATER TOTALS TO THIS AREA INCLUDING THE ROCHESTER METRO AREA. FEEL A BIT MORE CONFIDENT WITH THE AREA FROM WAYNE OVER TO NORTHERN CAYUGA AT THIS POINT...THEREFORE WILL ISSUE A LAKE EFFECT SNOW WATCH FOR THAT AREA...BUT IT IS HIGHLY POSSIBLE THAT LAKE EFFECT HEADLINES MAY NEED TO BE ISSUED FARTHER TO THE WEST. ANOTHER SHORTWAVE APPROACHING THE REGION FRIDAY NIGHT AND SATURDAY MAY REORIENT THE LAKES SNOWS FOR A TIME NORTHWARD AS THE FLOW BACKS TO WEST SOUTHWEST...POTENTIALLY BRINGING SOME ACCUMULATING SNOWS INTO PORTIONS OF THE BUFFALO METRO AND WATERTOWN AREAS. THE PASSAGE OF THE SHORTWAVE SHOULD RE-ESTABLISH THE LAKE SNOWS BACK SOUTHWARD LATER SATURDAY AND SATURDAY NIGHT. MUCH COLDER AIR MASS ACROSS THE AREA FRIDAY AND SATURDAY WITH DAYTIME HIGHS IN THE TEENS AND 20S...WITH WIND CHILLS PERIODICALLY BELOW ZERO. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... THE VERY COLD AIR REMAINS IN PLACE SUNDAY...BEFORE A GRADUAL MODIFICATION OF THE AIR MASS OCCURS INTO EARLY NEXT WEEK AS THE UPPER TROUGH SHIFTS TO THE EAST. TWO CLIPPER TYPE WAVES LOOK TO IMPACT THE LOWER LAKES REGION DURING THIS TIME FRAME. ONE WAVE MOVES THROUGH ON SUNDAY WHICH MAY SERVE TO ENHANCE THE ONGOING LAKE EFFECT SNOWS IN A WESTERLY FLOW REGIME. THE SECOND WAVE LOOKS TO MOVE THROUGH LATE MONDAY OR EARLY TUESDAY AND APPEARS TO BE RATHER ROBUST AND GIVEN THE PROJECTED TRACK OF THE ASSOCIATED SURFACE LOW COULD BRING THE POTENTIAL FOR A GENERAL WIDESPREAD SEVERAL INCHES OF SNOW. BEHIND THIS WAKE A COLDER FLOW DEVELOPS WHICH MAY REDEVELOP SOME LAKE SNOWS BUT LACK OF SIGNIFICANT MOISTURE COULD LIMIT SNOWFALL POTENTIAL. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... LLWS WILL QUICKLY SUBSIDE AS A STRONG LLJ EXITS TO THE EAST. MEANWHILE...A BROAD AREA OF SHOWERS WILL MOVE INTO THE REGION...BOTH STREAMING FROM THE SOUTH AND AHEAD OF A COLD FRONT. THIS WILL BRING A PERIOD OF RAIN TO ALL TAF SITES...BUT WITH THE SOUTHERLY DOWNSLOPE COMPONENT TO THE FLOW CIGS WILL BE INITIALLY SLOW TO DROP. AS THE COLD FRONT CROSS THE AREA BETWEEN 04Z AND 09Z...CIGS WILL DROP AND IFR CONDITIONS WILL BECOME MORE WIDESPREAD...ESPECIALLY DOWNWIND OF THE LAKES. RAIN WILL MIX WITH...THEN CHANGE TO SNOW BEFORE DAYBREAK THURSDAY. STRONG COLD AIR ADVECTION BEHIND THE DEPARTING FRONT WILL INCREASE MIXING AND RAPIDLY STRENGTHEN WESTERLY WINDS OVERNIGHT. LATE TONIGHT INTO THURSDAY MORNING...EXPECT WINDS TO GUST TO 40-50 KNOTS IN MOST LOCATIONS...BEFORE TAPERING OFF LATE THURSDAY AFTERNOON. LAKE SNOWS WILL DEVELOP EAST OF THE LAKES. THESE WILL LIKELY STAY OUT OF BUF/IAG/ROC...BUT SHOULD IMPACT ART/JHW FOR A PERIOD. CONDITIONS WILL VARY SIGNIFICANTLY IN AND OUT OF LAKE EFFECT BANDS. OUTLOOK... THURSDAY NIGHT THROUGH SATURDAY...MVFR WITH LOCALIZED IFR IN LAKE EFFECT SNOW EAST OF THE LAKES. SUNDAY...MAINLY VFR WITH MVFR IN LOCALIZED LAKE EFFECT SNOW SHOWERS. MONDAY...VFR. && .MARINE... A COMPLEX AREA OF LOW PRESSURE FROM SOUTHERN CANADA AND THROUGH THE CENTRAL GREAT LAKES REGION THIS AFTERNOON WILL LIFT NORTHEASTWARD AND DEEPEN TONIGHT AND TOMORROW. A COLD FRONT SWINGING ACROSS THE LAKES...COUPLED WITH STRONG COLD AIR ADVECTION AND RAPID DEEPENING OF THE SURFACE LOW WILL INCREASE WINDS QUICKLY TO GALE FORCE FOLLOWING THE PASSAGE OF THE FRONT TONIGHT...WITH GALES THEN CONTINUING THROUGH MUCH OF THURSDAY. FOR THIS REASON...GALE WARNINGS WILL CONTINUE AS OUTLINED ON THE LAKES. WINDS AND WAVES WILL STILL REMAIN STRONG THURSDAY EVENING THROUGH SATURDAY...BEFORE DIMINISHING TO BELOW SMALL CRAFT CONDITIONS BY SATURDAY NIGHT. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HIGH WIND WARNING UNTIL 4 PM EST THURSDAY FOR NYZ001>005-010- 011-019-020-085. LAKE EFFECT SNOW ADVISORY FROM 10 AM THURSDAY TO 6 PM EST FRIDAY FOR NYZ012-085. HIGH WIND WARNING FROM 10 PM THIS EVENING TO 4 PM EST THURSDAY FOR NYZ006>008. LAKE EFFECT SNOW ADVISORY FROM 10 AM THURSDAY TO 1 AM EST FRIDAY FOR NYZ007. FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR NYZ004>008-013-014- 021. LAKE EFFECT SNOW WARNING FROM 10 AM THURSDAY TO 6 PM EST FRIDAY FOR NYZ006-008-019-020. LAKE EFFECT SNOW WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON FOR NYZ004-005. WIND ADVISORY UNTIL 4 PM EST THURSDAY FOR NYZ012>014-021. FLOOD WATCH THROUGH THURSDAY MORNING FOR NYZ019-020. MARINE...GALE WARNING FROM 10 PM THIS EVENING TO 4 PM EST THURSDAY FOR LEZ040-041. GALE WARNING FROM 10 PM THIS EVENING TO 10 AM EST THURSDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR LOZ030. GALE WARNING FROM 1 AM TO 4 PM EST THURSDAY FOR LOZ042>045- 062>065. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...TMA LONG TERM...TMA AVIATION...APFFEL MARINE...THOMAS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
615 PM EST WED JAN 30 2013 .SYNOPSIS... WINDY AND MILD CONDITIONS WILL CONTINUE AHEAD OF A STRONG COLD FRONT. FAST MOVING SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT COULD PRODUCE LOCALIZED DAMAGING WIND GUSTS. DRY AND COOL CONDITIONS WILL FOLLOW THE FRONT THURSDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE MOVES INTO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM WEDNESDAY...THE STRONG COLD FRONT EXTENDS FROM EASTERN TENNESSEE TO THE FLORIDA PANHANDLE AND IS CATCHING UP QUITE RAPIDLY WITH THE PREFRONTAL SQUALL LINE. ALTHOUGH THERE ARE STILL SOME TIMING DIFFERENCES AMONG THE VARIOUS 12Z MODELS...THE CONSENSUS IS FOR THE FRONT TO ARRIVE IN THE SC PEE DEE REGION JUST BEFORE MIDNIGHT...MOVING THROUGH THE GRAND STRAND AND ELIZABETHTOWN/ WHITEVILLE AREAS AROUND MIDNIGHT...THEN THROUGH WILMINGTON AND THE CAPE FEAR COAST AROUND 1 AM. THIS WILL BE A VERY QUICK EVENT FOR ANY ONE LOCATION AND THE SQUALL LINE SHOULD TRAVERSE OUR ENTIRE FORECAST AREA IN 3 HOURS OR LESS. STRONG SOUTH WINDS OUT AHEAD OF THE FRONT/SQUALL LINE HAVE GUSTED TO 39 MPH IN FLORENCE AND 36 MPH IN WILMINGTON. GUSTS OVER 40 MPH SHOULD DEVELOP BEFORE SUNSET AS STRONGER WINDS IN THE 1000-2000 FT LAYER GET ENTRAINED IN TURBULENT MIXING THROUGHOUT THE DAYTIME BOUNDARY LAYER. AS THE SURFACE COOLS DOWN TO 68-70 DEGREES THIS EVENING AND THE BOUNDARY LAYER FLATTENS TO ONLY A FEW HUNDRED FEET THICK...WINDS AS LOW AS 1000 FT AGL WILL INCREASE TO 40-50 KNOTS. SOME OF THIS MOMENTUM MAY STILL TUMBLE DOWN TO THE SURFACE WITH GUSTS UP 45 MPH EXPECTED. A SQUALL LINE CONSISTING OF LINEAR FORCED CONVECTION WITHIN A REGION OF HIGHLY CONVERGENT LOW-LEVEL FLOW JUST AHEAD OF THE FRONT WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS VIA HEAVY RAINFALL TRANSPORTING STRONG WINDS DOWN FROM ALOFT. CONVECTIVE CELLS... ASSUMING A 15000 FT CELL DEPTH AND MOVEMENT AT 70% OF THE MEAN FLOW...COULD MOVE AS QUICKLY AS 65 KNOTS. THE POTENTIAL FOR WIDESPREAD DAMAGING WINDS DOES EXIST. ASSUMING SURFACE TEMPS OF 68-70 DEGREES AND SURFACE DEWPOINTS IN THE LOWER 60S...SURFACE-BASED CAPE SHOULD REMAIN NEAR ZERO TONIGHT. HOWEVER THE SURFACE-BASED INVERSION WILL ALSO BE WEAK AND MAY NOT PROVIDE AN EFFECTIVE BARRIER TO STRONG WINDS PUNCHING DOWN FROM ALOFT. THE BEST POTENTIAL FOR SEVERE WEATHER SHOULD BE NEAR AND WEST OF I-95...BUT EVEN AT THE COAST THE THREAT IS STILL LARGE ENOUGH FOR CONCERN. SEVERE THUNDERSTORM WATCHES WILL PROBABLY BE NEEDED FOR THE AREA TONIGHT. THANKFULLY...THE SHALLOW DEPTH OF THE CONVECTION PLUS WEAK UPDRAFT STRENGTH SHOULD PRECLUDE ANY HAIL THREAT. AFTER THE FRONT SLIDES OFFSHORE...MUCH DRIER COOLER AIR WILL BUILD IN WITH CLEARING SKIES. LOWS SHOULD RANGE FROM 45-50. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...STRONG WESTERLY WINDS WILL ADVECT MUCH COLDER AND DRIER AIR INTO REGION BEHIND EXITING COLD FRONT LOCATED WELL OFF THE COAST BY THURS MORNING. A VERY BROAD MID TO UPPER TROUGH WILL SHIFT EAST THROUGH THE PERIOD FINALLY LIFTING OFF TO THE NORTHEAST BY FRI NIGHT. AS THIS TROUGH MOVES EAST IT WILL DRIVE A SECONDARY BOUNDARY THROUGH THE AREA BY FRI MORNING. THIS WILL PROVIDE A REINFORCING SHOT OF COLD AND DRY AIR INTO THE AREA AS DEEP NW FLOW SETS UP ON FRIDAY. OVERALL A POTENT STORM SYSTEM WILL LIFT OFF TO THE NORTHEAST AS HIGH PRESSURE RIDGES UP FROM THE GULF COAST ON THURSDAY....BUT STRONG HIGH PRESSURE WILL BUILD DOWN FROM CANADA REACHING INTO THE CENTRAL CONUS BY THURS NIGHT AND SHIFTING EAST OVER THE LOCAL AREA BY LATE FRI INTO EARLY SAT. THIS WILL MAINTAIN A TIGHTENED GRADIENT FLOW THROUGH THURS AND THEN WINDS MAY BACK SLIGHTLY BEFORE NEXT DRY FRONTAL BOUNDARY MOVES THROUGH EARLY FRI WITH A SPIKE UP OF WINDS BEFORE FINALLY DIMINISHING AND VEERING MORE NORTH BY FRI NIGHT. THESE STRONG WEST TO NORTHWEST WINDS WILL MAINTAIN CAA THROUGH MUCH OF THE PERIOD. THERE WILL ONLY BE A BRIEF PERIOD OF MORE NEUTRAL ADVECTION AHEAD OF DRY COLD FRONT FRI MORNING. THEREFORE 850 TEMPS DROP FROM 13C JUST AHEAD OF INITIAL COLD FRONT EARLY THURS MORNING DOWN LESS THAN 0C BY THURS AFTN AND THEN WILL DROP AN ADDITIONAL SEVERAL DEGREES DOWN TO -8C BY FRI EVENING. TEMPS REACHING THE MID 50S...ALREADY 20 DEGREES COOLER THAN ON THURS...WILL HAVE TROUBLE REACHING INTO THE 50S ON FRI AS COLD ARCTIC HIGH PRESSURE BUILDS DOWN INTO THE AREA. OVERNIGHT LOWS WILL DROP DOWN TOWARD FREEZING THURS NIGHT IN CAA BUT FRI NIGHT TEMPS WILL PLUMMET ONCE WINDS DROP OFF IN THE EVENING. A MUCH MORE IDEAL RADIATIONAL COOLING NIGHT WILL OCCUR ON FRIDAY NIGHT AS HIGH SHIFTS OVERHEAD...MAKING FOR ONE OF THE COLDEST NIGHTS OF THE SEASON THUS FAR...WITH WIDESPREAD READINGS IN THE 20S. DRY AIR WILL RUN SIMILAR TO TEMPS WITH A MAJOR DROP OFF BEHIND FIRST FRONT AND THEN A PLATEAU AND MINOR INCREASE JUST AHEAD OF DRY POLAR COLD FRONT FRI MORNING AND THEN ANOTHER NOSE DIVE THROUGH FRI AFTN. THE PCP WATER DROP OFF FROM 1.6 INCHES VERY EARLY THURS MORNING DOWN TO A QUARTER OF AN INCH BY LATE THURS MORNING AND THEN DOWN CLOSE TO A TENTH OF AN INCH BY FRI AFTN. WITH SUCH A DRY AIR MASS IN PLACE...EXPECT SUNSHINE THROUGH MOST OF THE PERIOD. MAY SEE SOME CLOUDS WITH LINGERING MOISTURE THROUGH THURS MORNING AFTER RAINFALL FROM FRONT...AND A SLIGHT SPIKE AHEAD OF FRONT FRI MORNING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 PM WEDNESDAY...A RATHER REPETITIVE PATTERN FOR THE EXTENDED AS AREAS OF HIGH PRESSURE PUSH OFFSHORE AHEAD OF A SERIES OF WEAK COLD FRONTS. FIRST OF THESE OCCURS SATURDAY AS DIFFUSE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE...LEAVING A BRIEF PERIOD OF MOIST RETURN FLOW INTO THE CAROLINAS. THIS IS JUST IN ADVANCE OF A COLD FRONT WHICH WILL CROSS THE AREA VERY EARLY SUNDAY MORNING. LIMITED FORCING COMBINED WITH ONLY MARGINAL PWATS SUGGESTS FROPA WILL BE DRY...AND ONLY ACT TO REINFORCE THE COOL AIR. HOWEVER...ANY WEAK CAA REMAINS WELL DISPLACED BEHIND THE FRONT...SO SUNDAY WILL END UP BEING WARMER THAN SATURDAY...ALTHOUGH BOTH DAYS WILL BE AROUND TO SLIGHTLY BELOW CLIMO. ANOTHER LARGE BUT WEAK AREA OF HIGH PRESSURE BUILDS DOWN FROM THE NW LATE SUNDAY AND PERSISTS INTO TUESDAY WHILE SLOWLY DRIFTING ACROSS THE REGION. THIS CONTINUES THE COOL AND DRY WEATHER WITH NEAR TO SLIGHTLY-BELOW SEASONABLE TEMPS. THIS HIGH PRESSURE THEN DRIFTS OFFSHORE TUESDAY AHEAD OF ANOTHER COLD FRONT PROGGED TO CROSS THE AREA LATE IN THE DAY. GUIDANCE SHOWING CONSIDERABLE AMPLITUDE DIFFERENCES IN THE TROUGH DRIVING THIS FRONT WHICH WILL HAVE SIGNIFICANT IMPACT ON PRECIP POTENTIAL. FOR NOW WILL KEEP INHERITED SCHC/SILENT POP FOR D6 SINCE BENEFICIAL CHANGES CANNOT BE MADE AT THIS TIME. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD THOUGH AHEAD OF THE COLD FRONT...WITH TEMPS RETURNING TO BELOW CLIMO FOR WEDNESDAY AS ANOTHER AREA OF HIGH PRESSURE RIDGES DOWN FROM THE NW. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... AS OF 00Z...STRONG COLD FRONT TO IMPACT THE TERMINALS TONIGHT WITH GUSTY WINDS AND A POTENTIAL SQUALL LINE WITH SHOWERS/ISOLATED THUNDERSTORMS. COLD FRONT CURRENTLY ACROSS WESTERN PORTIONS OF SC/NC WILL PUSH EAST TONIGHT AND BE ACCOMPANIED BY A LINE OF SHOWERS WITH ISOLATED THUNDERSTORMS. HRRR APPEARS TO BE INITIALIZING BETTER THAN ANY OF THE OTHER HIGH-RES GUIDANCE...SO HAVE RELIED HEAVILY ON THIS MODEL FOR TIMING CONVECTION AT THE TERMINALS...AND EXPECT THE SQUALL LINE TO IMPACT FLO/LBT AROUND 03Z...RACING EAST TO ILM AROUND 06Z. ATTM...NO IFR HAS BEEN INTRODUCED INTO THE CURRENT SET OF TAFS DUE TO UNCERTAINTY IN EXACT TIMING AND LIKELY SHORT-DURATION OF ANY PRECIP INDUCED IFR. PREFER TO HANDLE ANY IFR WITH AMD/TEMPO GROUPS AS THE CONVECTION UNFOLDS. HAVE SHOWN A 2-HR TEMPO GROUP AT ALL TERMINALS FOR THE HEAVIEST CONVECTION WITH MVFR AND INCREASED WIND GUSTS...BUT STRONGER GUSTS ARE POSSIBLE THAN WHAT IS CURRENTLY DEPICTED. OTHER CONCERN IS THE STRONG PRE-FRONTAL AND POST-FRONTAL WINDS. S/SW WINDS WILL CONTINUE TO INCREASE TONIGHT AS A STRENGTHENING LOW LEVEL JET MOVES OVERHEAD. FOR THIS REASON HAVE SHOWN INCREASING LLWS IN ALL TAFS WITH 30 KT GUSTS LIKELY THROUGH THE NIGHT...EVEN OUTSIDE OF CONVECTION. A SUDDEN WIND SHIFT WILL OCCUR WITH THE FROPA TONIGHT...AND AWW`S MAY BE REQUIRED FOR ILM/MYR LATER TONIGHT AS THE FRONT CROSSES...AND WINDS SHIFT SUDDENLY TO THE WEST. RAPID DRYING OCCURS BEHIND THE FRONT AND SKC WILL BECOME THE SKY CONDITION ON THURSDAY. ALTHOUGH IT WILL BE CLEAR...STRONG WESTERLY WINDS WILL PERSIST THROUGH THE DAY...GUSTING TO 25 KTS THROUGH THE END OF THE VALID PERIOD. EXTENDED OUTLOOK...VFR THROUGH THE EXTENDED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM WEDNESDAY...SOUTH WINDS WILL INCREASE THROUGH THE EVENING AHEAD OF A STRONG COLD FRONT NOW LOCATED FROM EASTERN TENNESSEE SOUTH TO THE FLORIDA PANHANDLE. ALTHOUGH WINDS ARE CURRENTLY ONLY 20-30 KNOTS ACROSS THE COASTAL WATERS...A 3-4 HOUR PERIOD OF MUCH STRONGER WINDS IS EXPECTED TO DEVELOP JUST AHEAD OF THE FRONT THIS EVENING. 35-40 KNOT WINDS MAY GUST MUCH HIGHER AS A NARROW LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS PUSH OFFSHORE JUST AFTER MIDNIGHT. A SEVERE THUNDERSTORM WATCH PROBABLY WILL BE NEEDED TO ADDRESS THIS POTENTIAL. BEHIND THE FRONT...WINDS WILL TURN WESTERLY IN THE 25-35 KNOT RANGE THROUGH DAYBREAK. SEAS CURRENTLY 4-7 FT WILL BUILD THIS EVENING TO 8-12 FEET AWAY FROM SHORE WITH THE STRONG SOUTH WINDS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...ALTHOUGH SEAS WILL BE ON THE DECREASE THROUGH MUCH OF THE PERIOD IN STRONG OFF SHORE FLOW...TIGHTENED GRADIENT FLOW AND COLD SURGE BEHIND FRONT THURS AND AGAIN ON FRI WILL MAINTAIN SEAS ABOVE SCA THROUGH A GOOD PORTION OF THE SHORT TERM PERIOD IN THE OUTER WATERS. WESTERLY WINDS UP AROUND 25 KTS WILL DROP THROUGH THURS ALLOWING OFF SHORE SEAS TO SUBSIDE FROM 8 TO 10 FT FRI MORNING DOWN TO 5 FT BY THURS NIGHT. WINDS WILL BACK SLIGHTLY TO THE SW THURS NIGHT INTO EARLY FRI AHEAD OF APPROACHING DRY COLD FRONT BEFORE SPIKING UP IN SURGE BEHIND FRONT. THIS WILL PRODUCE SEAS AROUND 6 FT ONCE AGAIN FOR A FEW HOURS ON FRI. THE NEAR SHORE WATERS WILL DECREASE THROUGH THURS IN OFF SHORE FLOW DOWN TO 2 TO 4 FT AND MAY SPIKE UP A BIT FRI MORNING BUT OVERALL WILL DROP OFF SOME MORE LATE FRI AS HIGH PRESSURE SHIFTS OVERHEAD ALLOWING FOR LOCAL SEAS TO DROP TO 2 TO 3 FT IN ALL WATERS. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 PM WEDNESDAY...OTHER THAN A WEAK COLD FRONT SUNDAY...DIFFUSE HIGH PRESSURE WILL DOMINATE THE WEATHER ACROSS THE WATERS THROUGH THE EXTENDED. ONE AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WATERS SATURDAY CREATING LIGHT AND VARIABLE WINDS...VEERING TO THE SW AND INCREASING TO AROUND 10 KTS LATE IN THE DAY. THIS AHEAD OF A COLD FRONT WHICH WILL CROSS DURING SUNDAY...TURNING WINDS TO THE W/NW AT 10-15 KTS ON SUNDAY BEFORE SLOWLY EASING TO LIGHT AND VARIABLE AGAIN MONDAY AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. SEAS WILL BE PRIMARILY WIND-DRIVEN THROUGH THE PERIOD...1-2 FT SATURDAY AND MONDAY...INCREASING FOR A SHORT TIME SUNDAY UP TO 2-4 FT WITH A NW WIND WAVE DOMINANT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR SCZ017-023-024-032- 033-039-053>056. NC...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR NCZ087-096-099- 105>110. MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST THURSDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...JDW AVIATION...JDW
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1043 PM MST MON JAN 28 2013 .UPDATE...SLOW MOVING BAROCLINIC ZONE AND ASSOCIATED DISTURBED MID LEVEL JET AXIS CONTINUES TO SHIFT EAST...WITH SNOW SLOWLY TRENDING EAST OUT OF THE FA. ANOTHER SUBTLE IMPULSE IS EJECTING NE ACROSS NEB AND WILL SUPPORT CONTINUED SNOW ACROSS FAR SCNTRAL SD...ALTHOUGH SNOW WILL WANE IN INTENSITY AS THE BEST LIFT AND BETTER MOISTURE CONTINUES TO SHIFT EAST. HENCE...DROPPED THE WEST END OF THE ADV...RETAINING THE EASTERN PORTION WHERE ANOTHER 1 TO 2 INCHES OF SNOW IS POSSIBLE INTO EARLY MORNING. OTHERWISE...ADJUSTED SKY GRIDS GIVEN SOME EXPECTED CLEARING PER WAKE SUBSIDENCE. && .AVIATION...06Z TAFS UPPER LEVEL IMPULSE AND ASSOCIATED SNOW WILL CONTINUE TO SHIFT EAST ACROSS THE REGION. MVFR/IFR CONDITIONS OVER MUCH OF SOUTH CENTRAL AND CENTRAL SOUTH DAKOTA WILL TREND UP TO HIGH END MVFR AND VFR THROUGH THE PERIOD AS THIS DISTURBANCE EXITS THE REGION AND SNOW ENDS EARLY TUES MORNING. VFR CONDITIONS EXPECT MOST PLACES INTO TUES AFTERNOON. A FAST MOVING CLIPPER SYSTEM WILL PUSH INTO THE NORTHERN PLAINS TUESDAY AFTERNOON...AFFECTING THE FA NW-SE THROUGH THE AFTERNOON AND EVENING PERIOD. SNOW WILL BE POSSIBLE OVER MUCH OF THE REGION...ESP OVER NE WY AND THE NORTHERN BLACK HILLS WITH MVFR AND POSSIBLE IFR FLIGHT RESTRICTIONS THERE. HAVE ADDED A TREND TOWARD MVFR AT GCC...WITH RAP EXPECTED TO REMAIN VFR. THE SYSTEM WILL BRING WINDY CONDITIONS TO THE REGION...ESP IN THE LEE OF THE BLACK HILLS. HAVE ADDED GUSTY SUSTAINED WINDS AT KRAP TUE EVENING. .PREV DISCUSSION... /ISSUED 303 PM MST MON JAN 28 2013/ DISCUSSION...WATER VAPOR SHOWS SHARP TROF MOVING INTO THE ROCKIES...WITH JET ENERGY EJECTING NEWD FROM THE CNTRL ROCKIES THROUGH THE NRN PLAINS. AT THE SURFACE...LOW CENTER IS DEEPENING OVER ERN CO WITH LIGHT NLY FLOW ACROSS OUR CWFA. SNOW CONTINUES TO FALL MAINLY FROM THE BLKHLS EWD. TONIGHT...BEST LIFT TRANSLATES INTO SCNTRL SD AS NEXT JET STREAK NOSES THROUGH THE CNTRL PLAINS AND SFC LOW PUSHES EWD ALONG THE NEB/KS BORDER. STRONG 850-700MB FRONTOGENESIS AND MID LEVEL INSTABILITY EXPECTED ACROSS SCNTRL SD. 3-5 INCHES OF SNOW POSSIBLE...ALTHOUGH HIGHER AMOUNTS QUITE POSSIBLE WITHIN HEAVIER BANDS THAT SET UP. HAVE COVERED WITH A WINTER WX ADVISORY. LIFT/SNOW SHOULD PUSH EAST OF THE AREA BY DAYBREAK. TUESDAY...UPPER TROF AXIS SHIFTS INTO THE CNTRL DAKOTAS AS STRONG SHORTWAVE BEGINS DROPPING DOWN BACK SIDE OF TROF. ARCTIC COLD FRONT DIVES SOUTHWARD...REACHING NERN WY/WRN SD LATE IN THE DAY. GUSTY NW WINDS...POSSIBLY REACHING LOWER END ADVISORY ACROSS NWRN SD...WILL PUSH ACROSS THE AREA TUESDAY AFTN/EVE. WIND CHILLS BY LATE TUESDAY NIGHT SHOULD DROP UNDER 20 BELOW ZERO ACROSS NWRN SD. POST FRONTAL LIGHT SNOW/FLURRIES EXPECTED...WITH UPSLOPE ENHANCEMENT ACROSS THE NRN BLKHLS. WEDNESDAY...ARCTIC HIGH BUILDS INTO THE DAKOTAS ON WEDNESDAY...WITH 850-700MB BAROCLINIC ZONE ACROSS NORTHEAST WYOMING/SOUTHWEST SOUTH DAKOTA. SOME LINGERING LIGHT SNOW/FLURRIES POSSIBLE...WITH CONTINUING UPSLOPE ENHANCEMENT IN THE NRN BLKHLS. EXTENDED...ARCTIC AIR WILL HANG AROUND THE AREA ON THURSDAY... COLDEST NORTH AND EAST OF THE BLACK HILLS...BEFORE BEGINNING TO PUSH OUT LATE THURSDAY AND THURSDAY NIGHT. LINGERING SNOW IS EXPECTED ACROSS NORTHEASTERN WY AND FAR WESTERN SOUTH DAKOTA THURSDAY...ESPECIALLY ACROSS UPSLOPE ENHANCED AREAS OF THE NORTHERN BLACK HILLS THURSDAY MORNING. SNOW WILL GRADUALLY TAPER OFF THURSDAY NIGHT...AND EVEN AS LATE AS FRIDAY OVER THE NORTHERN HILLS. THE ARCTIC BOUNDARY WILL PUSH EAST OF THE AREA FRIDAY BRINGING MUCH WARMER TEMPERATURES TO THE AREA HEADING INTO THE WEEKEND ALONG WITH DRY WEATHER. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR MELLETTE-TODD- TRIPP. WY...NONE. && $$ SHORT TERM...JOHNSON EXTENDED...13 AVIATION...JC UPDATE...JC
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1059 AM CST TUE JAN 29 2013 .DISCUSSION... /SEE BELOW FOR AVIATION DISCUSSION/ && .AVIATION... PACIFIC FRONT EXTENDED EAST OF AN OZONA...SAN ANGELO...ABILENE... THROCKMORTON LINE AT 11 AM...MOVING EAST. WEST WINDS WILL INCREASE RAPIDLY EARLY THIS AFTERNOON...WITH GUSTS OF 40 KTS AT KSJT AND KABI. WINDS SHOULD DECREASE AFTER 0Z...OR 6 PM. AN ISOLATED THUNDERSTORM POSSIBLE AT KBBD...KSOA...AND KJCT THIS AFTERNOON. BEST POTENTIAL WILL BE A KBBD WHERE I WILL INCLUDE A VCTS. VISIBILITIES MAY FALL SLIGHTLY IN BLOWING DUST LATE THIS AFTERNOON OR EARLY EVENING...BUT EXPECT THEM TO REMAIN ABOVE 5 SM. && .PREV DISCUSSION... /ISSUED 1000 AM CST TUE JAN 29 2013/ UPDATE... UPATED TO ADD MORNING THUNDERSTORM FARTHER WEST. INCREASED TEMPERATURES AND DEW POINTS. DISCUSSION... DRYLINE AND SURFACE TROUGH WERE FARTHER WEST THIS MORNING WITH MID LEVEL CLOUDS PREVENTING MIXING. THUNDERSTORMS WERE DEVELOPING BETWEEN OZONA AND MERTZON ALONG THE TROUGH. POTENTIAL EXISTS FOR A STRONG..POSSIBLY EVEN A SEVERE STORM AS THE SURFACE TROUGH MOVES EAST THROUGH EARLY AFTERNOON...MAINLY ALONG AND EAST AF A SAN ANGELO TO ABILENE TO THROCKMORTON LINE WITH RUC SFC BASE CAPES OF 1500 TO 1900 J/KG. 04 PREV DISCUSSION... /ISSUED 516 AM CST TUE JAN 29 2013/ AVIATION... /12Z UPDATE/ VFR CONDITIONS WILL CONTINUE OVER THE NORTHERN TERMINALS THROUGH THE TAF PERIOD. MVFR CEILINGS OVER THE SOUTHERN TERMINALS WILL LIFT TO VFR BY NOON...REMAINING VFR FOR THE REMAINDER OF THE TAF PERIOD. A COLD FRONT WILL MOVE QUICKLY EAST THROUGH THE AREA THIS MORNING BRINGING HIGH WINDS TO THE TERMINALS. SURFACE WINDS WILL CONTINUE TO INCREASE IN SPEED THROUGH THE DAY. KABI CAN EXPECT WESTERLY GUSTS TO OVER 30KT FOR MOST OF THE DAY WITH GUSTS AS HIGH AS 45KT BY NOON. WINDS AT KSJT WILL GUST TO AROUND 35KT BY NOON. FOR THE SOUTHERN TERMINALS EXPECT WIND GUSTS FROM 25KT TO 35KT BY NOON. WINDS WILL DECREASE TO LESS THAN 20KT BY THIS EVENING AT ALL TERMINALS. BLDU WILL REDUCE VISIBILITIES AT THE NORTHERN TERMINALS BY NOON TO AROUND 6SM. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 69 34 56 31 68 / 20 5 0 0 0 SAN ANGELO 70 36 56 27 68 / 20 0 0 0 0 JUNCTION 72 35 59 26 68 / 20 5 0 0 0 && .SJT WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 7 PM CST THIS EVENING FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE... COLEMAN...CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES... KIMBLE...MENARD...NOLAN...RUNNELS...SCHLEICHER...SHACKELFORD... STERLING...SUTTON...TAYLOR...THROCKMORTON...TOM GREEN. WIND ADVISORY UNTIL 7 PM CST THIS EVENING FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE...COLEMAN...CONCHO...CROCKETT... FISHER...HASKELL...IRION...JONES...MCCULLOCH...NOLAN...RUNNELS... SHACKELFORD...STERLING...TAYLOR...THROCKMORTON...TOM GREEN. && $$ 99/99/04
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1000 AM CST TUE JAN 29 2013 .UPDATE... UPATED TO ADD MORNING THUNDERSTORM FARTHER WEST. INCREASED TEMPERATURES AND DEW POINTS. && .DISCUSSION... DRYLINE AND SURFACE TROUGH WERE FARTHER WEST THIS MORNING WITH MID LEVEL CLOUDS PREVENTING MIXING. THUNDERSTORMS WERE DEVELOPING BETWEEN OZONA AND MERTZON ALONG THE TROUGH. POTENTIAL EXISTS FOR A STRONG..POSSIBLY EVEN A SEVERE STORM AS THE SURFACE TROUGH MOVES EAST THROUGH EARLY AFTERNOON...MAINLY ALONG AND EAST AF A SAN ANGELO TO ABILENE TO THROCKMORTON LINE WITH RUC SFC BASE CAPES OF 1500 TO 1900 J/KG. 04 && .PREV DISCUSSION... /ISSUED 516 AM CST TUE JAN 29 2013/ AVIATION... /12Z UPDATE/ VFR CONDITIONS WILL CONTINUE OVER THE NORTHERN TERMINALS THROUGH THE TAF PERIOD. MVFR CEILINGS OVER THE SOUTHERN TERMINALS WILL LIFT TO VFR BY NOON...REMAINING VFR FOR THE REMAINDER OF THE TAF PERIOD. A COLD FRONT WILL MOVE QUICKLY EAST THROUGH THE AREA THIS MORNING BRINGING HIGH WINDS TO THE TERMINALS. SURFACE WINDS WILL CONTINUE TO INCREASE IN SPEED THROUGH THE DAY. KABI CAN EXPECT WESTERLY GUSTS TO OVER 30KT FOR MOST OF THE DAY WITH GUSTS AS HIGH AS 45KT BY NOON. WINDS AT KSJT WILL GUST TO AROUND 35KT BY NOON. FOR THE SOUTHERN TERMINALS EXPECT WIND GUSTS FROM 25KT TO 35KT BY NOON. WINDS WILL DECREASE TO LESS THAN 20KT BY THIS EVENING AT ALL TERMINALS. BLDU WILL REDUCE VISIBILITIES AT THE NORTHERN TERMINALS BY NOON TO AROUND 6SM. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 69 34 56 31 68 / 20 5 0 0 0 SAN ANGELO 70 36 56 27 68 / 20 0 0 0 0 JUNCTION 72 35 59 26 68 / 20 5 0 0 0 && .SJT WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 7 PM CST THIS EVENING FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE... COLEMAN...CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES... KIMBLE...MENARD...NOLAN...RUNNELS...SCHLEICHER...SHACKELFORD... STERLING...SUTTON...TAYLOR...THROCKMORTON...TOM GREEN. WIND ADVISORY UNTIL 7 PM CST THIS EVENING FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE...COLEMAN...CONCHO...CROCKETT... FISHER...HASKELL...IRION...JONES...MCCULLOCH...NOLAN...RUNNELS... SHACKELFORD...STERLING...TAYLOR...THROCKMORTON...TOM GREEN. && $$ 99/99
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1023 AM PST Tue Jan 29 2013 .SYNOPSIS... The weather pattern will remain active and wintry through Thursday as a number of storm systems will result in periodic heavy snow accumulations. There will be a break in the weather today...however another extended snow event looks likely for the region with the focus of the heavier snow again for the higher terrain of the Central Idaho Panhandle...the Blue mountains and the Camas Prairie. High pressure will build into the region at the end of the work week and linger into the weekend with fog and low stratus expected across much of the basin and in the valleys. && .DISCUSSION... rest of today...Looks like round two of the recent winter events has generally wound down this morning. Radar no longer detecting any precipitation over the Inland NW...while local webcams and mesonet not detecting any either. Satellite was showing that much of the mid and high level cloudiness has departed south and east of the forecast area...with little upstream at this time. With a dried out dendritic layer...there is little chance of additional significant snow through the remainder of the day. Given current trends and observations we have ended the winter weather highlights for the Camas Prairie and Blue Mountains. Although both locations could see some showers later today...additional accumulations will be light. For the remainder of the forecast area...the main changes revolved around lowering the sky cover through the afternoon. The latest visible satellite imagery was showing large holes in the high overcast...with the main cloud cover now being attributed to low stratus across portions of NE Washington and N Idaho. Clouds will increase once again late this afternoon...as the next winter disturbance rounds the top of the ridge and drops into the north Cascades via British Columbia. fx && .AVIATION... 18Z TAFS: main trouble spots this morning are along the KGEG-KCOE corridor due to areas of stratus and IFR cigs. Feel confident that these should be mainly gone before 20-21z...with VFR conditions after that. All remaining sites should be VFR through the daytime hours. For tonight...the next winter system will come into play. The latest HRRR has delayed the onset of the pcpn until aft 04z for all sites xcp MWH and EAT. Feel confident that the pcpn will be -sn for all sites xcp LWS and that IFR conditions will ensue shortly after the onset of pcpn. Looks like the eastern sites should see abt 6hrs of pcpn...aft which the main concern will be widespread stratus and fog. MOS guidance is suggesting IFR conditions for all the eastern sites and we have generally followed suit. fx && .PRELIMINARY POINT TEMPS/POPS... Spokane 33 26 36 30 36 27 / 10 70 40 30 40 30 Coeur d`Alene 33 26 35 31 36 28 / 10 70 50 50 70 40 Pullman 36 27 39 33 39 30 / 10 70 70 70 60 50 Lewiston 43 32 44 37 46 32 / 10 70 70 70 60 40 Colville 34 25 35 30 41 26 / 10 60 20 20 30 30 Sandpoint 34 26 34 28 36 28 / 10 70 60 60 70 60 Kellogg 32 25 35 30 39 29 / 20 80 80 80 80 70 Moses Lake 39 28 41 29 41 27 / 0 10 10 10 10 10 Wenatchee 36 28 38 29 39 27 / 0 20 10 10 10 10 Omak 34 24 31 24 36 25 / 10 40 10 10 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1130 PM MST WED JAN 30 2013 .UPDATE... ISSUED AT 1130 PM MST WED JAN 30 2013 BASED ON RADAR AND SATELLITE OBSERVATIONS...THE PERSISTENT SNOW BANDS THAT BROUGHT SNOW TO THE I-70 CORRIDOR HAVE SHIFTED EASTWARD WITH CONDITIONS IMPROVING FROM RIFLE TO SILT BASED ON OBSERVATIONS AND WEBCAMS. THIS IS CONSISTENT WITH THE LATEST RAP DATA SHOWING LITTLE IF ANY ADDITIONAL ACCUMULATIONS HERE. THEREFORE CANCELLED THE WINTER WEATHER ADVISORY FOR COZ007. WEBCAMS AND RADAR STILL SHOW SNOW BANDS STREAMING ACROSS THE FLATTOPS...THE I-70 CORRIDOR FROM GLENWOOD SPRINGS TO VAIL PASS...AND STEAMBOAT. REMAINING HIGHLITES LOOK ON TRACK. UPDATE ISSUED AT 536 PM MST WED JAN 30 2013 PERSISTENT SNOW OVER THE I-70 CORRIDOR WEST OF EAGLE AND EAST OF PALISADE HAD ALREADY BROUGHT 1 TO 2 INCHES OF SNOW TO THESE AREAS EARLY THIS EVENING. LATEST NAM12 AND RAP13 DATA INDICATED THIS PERSISTENT BAND OF SNOW COULD LAST THROUGH THE EVENING BRINGING FROM 2 TO 5 INCHES OF BY EARLY MORNING. THEREFORE...A WINTER WEATHER ADVISORY HAS BEEN ISSUED ZONES 7 AND 8. AREAS IN ZONE 8 ARE NOT INCLUDED IN THIS ADVISORY. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 302 PM MST WED JAN 30 2013 SNOW AND WIND IMPACTING THE NERN PART OF THE FORECAST AREA TODAY. CLASSIC OROGRAPHIC SNOW IN NORTHWEST FLOW AS PACIFIC MOISTURE AND STRONG JET TARGETS THE PARK/GORE RANGES AND THE FLAT TOP MOUNTAINS. MT WERNER SENSORS SHOW WIND OF 25 MPH BUT GUSTS TO AROUND 40 MPH. GIVEN LOW SNOW TO LIQUID RATIO VALUES...WEB CAMS SHOWING POOR VISIBILITY OVER THE MOUNTAIN PASSES. SNOTEL SITES SHOWING 6 HOUR QPF GENERALLY RANGING FROM /0.20/ TO /0.50/ INCHES...BUT THIS MAY EQUATE TO 5 TO 13 INCHES OF SNOW IF LIQUID TO WATER RATIO IS AROUND 25:1 OR HIGHER. THE HEAVIEST SNOW APPEARS CONFINED ABOVE 8500 FEET...OBSERVATIONS FROM THE PUBLIC AND SPOTTER REPORTS SUGGEST ONLY LIGHT SNOW IN THE MOUNTAIN VALLEYS (FROM MARBLE AND ASPEN). MODEL DATA KEEPS MOISTURE STREAM AND OROGRAPHIC SNOW ONGOING THROUGH THE NIGHT...BUT GRADUALLY TAPERS OFF ON THURSDAY. GRADIENT FLOW DOES WEAKEN ON THURSDAY WITH MOISTURE STREAM SOMEWHAT WEAKER...THEREFORE EXPECT SNOWFALL RATES TO DIMINISH ON THURSDAY. NO CHANGES TO THE CURRENT WINTER STORM WARNINGS AS ACCUMULATING SNOWFALL COMBINED WITH WIND WILL PERSIST INTO THURSDAY. IN ADDITION...AN EMBEDDED DISTURBANCE IN NORTHWEST FLOW RACES ACROSS THE NRN DIVIDE MOUNTAINS LATE THURSDAY AFTERNOON. ONCE THIS SHORT WAVE CROSSES THE DIVIDE...EXPECT SNOW AND WIND TO TAPER OFF CONSIDERABLY. FOR THE REMAINDER OF THE FORECAST AREA...MUCH OF EASTERN UTAH AND EXTREME WRN COLORADO WILL BE DRY. EXTENSIVE CLOUD COVER THAT COVERS MUCH OF THE REGION TODAY WILL GRADUALLY ERODE AWAY. MORE SUN EXPECTED ON THURSDAY ACROSS THE SWRN HALF OF THE FORECAST AREA. WITH LESS CLOUD COVER... EXPECT OVERNIGHT TEMPS ON FRIDAY MORNING TO BE THE COLDEST OF THE WEEK FOR THE NRN AND CENTRAL VALLEYS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 302 PM MST WED JAN 30 2013 A WAVE IN NW FLOW WILL CLIP NW CO FRI AS IT MOVES INTO THE PLAINS. THE GFS/ECMWF/CANADIAN MODELS IN GENERAL AGREEMENT HERE AND HAVE BOOSTED POPS FOR THE ELKHEAD AND PARK RANGES BASED ON THIS. A PERIOD OF Q-FORCING ALOFT WITH WARM ADVECTIVE UPLIFT AT MTN TOP LEVEL AND WITH W-NW OROGRAPHICS SHOULD RESULT IN SOME AREAS OF SNOW FROM ABOUT MIDDAY FRI INTO FRI EVENING. THIS WEEKEND LOOKS DRY AS THE WEST COAST RIDGE SLIDES OVER THE FORECAST AREA. A SMALL CLOSED LOW CURRENTLY DEVELOPING OFF THE CA COAST IS FORECAST TO SHEAR INLAND AND WEAKEN WHILE A LARGER PACIFIC TROUGH SPLITS AS IT APPROACHES THE COAST. THIS MORNING/S MODELS WERE IN GENERAL AGREEMENT WITH TAKING THE SOUTHERN PORTION OF THE SPLIT AND FORMING A CUT-OFF LOW WELL OFF THE CA COAST...WHILE THE NORTHERN SPLIT BRUSHES OUR FORECAST ABOUT SUNDAY. NEITHER THE GFS NOR ECMWF SHOW MUCH CHANCE OF SIGNIFICANT PRECIPITATION THOUGH FROM THE NORTHERN WAVE THOUGH. GFS HAS BEEN INCONSISTENT HANDLING THE SOUTHERN SPLIT CUT-OFF LOW...ALTERNATING BETWEEN BRINGING TO ABOUT THE 4 CORNERS BY TUE AND KEEPING IT OFFSHORE INLINE WITH THE MORE CONSISTENT ECMWF. FOLLOWING MORE THE PREFERRED ECMWF WOULD RESULT IN GENERAL RIDGING OVER ERN UT/WRN CO EARLY NEXT WEEK AND A MINIMAL CHANCE OF PRECIP. BUT BOTH THE GFS AND ECMWF SHOW A DECENT TROUGH APPROACHING THE PACIFIC NW COASTLINE ON WEDNESDAY...FOR POTENTIALLY UNSETTLED WEATHER LATE NEXT WEEK. TEMPERATURES ARE EXPECTED TO GRADUALLY MODERATE THIS PERIOD ALTHOUGH TEMPS WILL STILL BE A BIT OF A CHALLENGE IN MANY VALLEYS. SNOW COVER WILL KEEP TEMPS IN THE EASTERN UINTA BASIN LAGGING THE MOST BEHIND...HOWEVER...WHERE AN INVERSION SHOULD BE SLOW TO ERODE. INVERSIONS WILL NOT BE A STRONG FOR THE GRAND VALLEY WHERE SNOW COVER IS DIMINISHING IN AREAL EXTENT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1015 PM MST WED JAN 30 2013 A PERSISTENT MOIST NORTHWEST FLOW WILL CONTINUE TO DELIVER SNOW TO THE NORTHERN AND CENTRAL MOUNTAINS AND ADJACENT VALLEYS DURING THE REMAINDER OF THE NIGHT. AS A RESULT...EXPECT KSBS AND KASE TO HAVE PERSISTENT MVFR CIGS AND VSBY WITH OCCASIONAL IFR CONDITIONS DURING MUCH OF THE REMAINDER OF THE NIGHT WITH SURROUNDING MOUNTAINS OBSCURED IN SNOW. KRIL...KGWS...AND KGUC WILL HAVE OCCASIONAL MVFR CIGS AND VSBY IN SNOW SHOWERS THROUGH 12Z THURSDAY. MODELS CONTINUE TO GENERATE MOUNTAIN SNOW OVER THE NORTHERN AND CENTRAL MOUNTAINS THURSDAY THROUGH MIDNIGHT...THOUGH LIGHTER IN INTENSITY AND LESS EXTENSIVE. ADJACENT TERMINALS ARE UNLIKELY TO DROP BELOW VFR CONDITIONS THURSDAY. AREAS WEST OF A KPSO TO KCAG LINE WILL HAVE VFR CONDITIONS THROUGH THE NEXT 24 HOURS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 2 AM MST THURSDAY FOR COZ008. WINTER STORM WARNING UNTIL 6 PM MST THURSDAY FOR COZ004-005-010- 013. UT...NONE. && $$ UPDATE...MDA SHORT TERM...PF LONG TERM...JAD AVIATION...NL
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1000 PM MST WED JAN 30 2013 .UPDATE...NO CHANGES NEED TO THE CURRENT FORECAST. WINDS CONTINUE TO BLOW OVER THE MOUNTAINS AND FOOTHILLS WITH GUSTS IN THE 40 TO 60 MPH RANGE...WITH BERTHOUD PASS JUST GUSTING TO 65 MPH. SNOTEL OBSERVATIONS STILL SHOWING THE OROGRAPHIC SNOW PRODUCTION...WITH AREAS RECEIVING BETWEEN HALF AN INCH TO UP TO AN INCH AN HOUR WITH THE HIGHEST AMOUNTS NEAR RABBIT EARS PASS. WINTER STORM WARNING STILL IN EFFECT UNTIL THURSDAY EVENING. SOME OF THE LATEST MODELS ARE SHOWING LESS MOISTURE UPSTREAM...SO THE ENDING TIME OF THE WARNING MAY HAVE TO BE ADJUSTED. HOWEVER...THE WIND WILL CONTINUE TO BE QUITE STRONG TO CONTRIBUTE TO THE HAZARDOUS WEATHER. && .AVIATION...SOUTHWEST WILL PREVAIL TONIGHT AT DEN AND APA AS DRAINAGE FLOW DEVELOPS WITH SPEEDS AROUND 12 KTS. WINDS TO REMAIN WEST TO NORTHWEST AT BJC THROUGH THE EVENING AND OVERNIGHT...WITH SOME GUSTS TO 40 KTS POSSIBLE AFTER 06Z. ON THURSDAY...WINDS TO BECOME NORTHWEST AND WEAKEN ACROSS THE AREA AFTER 16Z. SOME GUSTS TO 25 KTS WILL BE POSSIBLE AT BJC. VFR TO PREVAIL. && .PREV DISCUSSION... /ISSUED 355 PM MST WED JAN 30 2013/ SHORT TERM...STRONG NORTHWEST FLOW ALOFT OVER AREA WITH OROGRAPHICS CONTINUING ACROSS MOUNTAINS. WEB CAMS INDICATE SNOW CONTINUING ACROSS MOUNTAINS...THOUGH HAS SHOWN SOME SIGNS OF DECREASING DURING THE PAST FEW HOURS. STABILITY HAS BEEN LIMITED...WHICH HAS HINDERED THE HEAVIER SNOW RATES. STILL..WINDS BEEN QUITE GUSTY ACROSS THE RIDGES...WITH A RECENT GUST TO 71 MPH ATOP BERTHOUD PASS WHILE OTHER GUSTS WERE MAINLY IN THE 50S. THE WINDS WERE CREATING AREAS OF BLOWING SNOW ACROSS THE MOUNTAIN PASSES. GUSTY WINDS ALSO OCCURRING IN AND NEAR FOOTHILLS WITH GUSTS MAINLY IN THE 40S. ACROSS PLAINS WEAK MESOCYCLONE SLIDING SOUTH ACROSS MORGAN COUNTY KEEPING GUSTY WINDS FROM SPREADING EAST ACROSS URBAN CORRIDOR. FLOW ALOFT REMAINS STRONG TONIGHT AND INCREASES SLIGHTLY AS SHOWN BY RAP CROSS SECTIONS. AIRMASS TO REMAIN QUITE MOIST ACROSS THE MOUNTAINS ALONG WITH CONTINUED OROGRAPHICS AND SNOWFALL. STABILITY SHOULD IMPROVE OVERNIGHT... HELPING WITH SNOWFALL RATES. ADDITIONAL 3 TO 6 INCHES STILL POSSIBLE ON FAVORED WEST FACING SLOPES WITH LESSER AMOUNTS ELSEWHERE. MODEL CROSS SECTIONS SHOW WEAK MOUNTAIN WAVE DEVELOPING OVERNIGHT WHICH WILL HELP TO INCREASE WINDS. GUSTS AROUND 70 MPH POSSIBLE ALONG THE HIGHER RIDGES...WITH GUSTS UP TO 60 MPH ALONG THE FOOTHILLS. THE GUSTY WINDS WILL CONTINUE TO CREATE CONSIDERABLE BLOWING SNOW OVER THE MOUNTAIN PASSES WITH POSSIBLE WHITE OUT CONDITIONS ABOVE TIMBERLINE. ACROSS PLAINS...WINDS TO BE A BIT GUSTY NEAR THE FOOTHILLS AND WYOMING BORDER WITH LESS WIND ELSEWHERE. MODELS CONTINUE TO SHOW AN AREA OF LIGHT SNOW DEVELOPING ALONG THE WYOMING BORDER TONIGHT IN VICINITY OF UPPER JET. OTHERWISE...DRY CONDITIONS TO PREVAIL. ON THURSDAY...STRONG NORTHWEST FLOW ALOFT TO CONTINUE THOUGH MODEL CROSS SECTIONS INDICATE MOISTURE ACROSS MOUNTAINS DECREASING BY THE AFTERNOON AS STABILITY INCREASES. STILL DECENT OROGRAPHICS IN PLACE FOR MUCH OF THE DAY ALONG WITH GUSTY WINDS. SHOULD SEE SNOW GRADUALLY DECREASE DURING THE DAY THOUGH THERE WILL STILL BE QUITE A BIT OF BLOWING SNOW. WILL MAINTAIN THE WARNING THROUGH THE DAY THOUGH ADDITIONAL SNOWFALL SHOULD BE LIGHT. WINDS TO BE A BIT GUSTY IN AND NEAR THE FOOTHILLS AS A WEAK SURFACE TROUGH IS EXPECTED TO DEVELOP. FURTHER EAST...MODELS CONTINUE TO SHOW A WEAK COLD FRONT MOVING INTO THE NORTHEAST CORNER. WITH UPPER JET IN VICINITY... THERE COULD BE A SLIGHT CHANCE OF LIGHT SNOW IN THE FAR NEAR THE WYOMING BORDER. OTHERWISE DRY CONDITIONS WILL PREVAIL. LONG TERM...A RATHER BENIGN WEEK OF WEATHER IS EXPECTED AFTER THE SNOW SHOWERS CLEAR OUT OF THE MOUNTAINS THURSDAY NIGHT. ON THURSDAY EVENING...A FEW SNOW SHOWERS MAY BE LINGERING...BUT THEY WILL BE ON THE DECREASE AS SUBSIDENCE OVER THE STATE INCREASES. DRY...NORTHWESTERLY FLOW ALOFT IS FORECAST TO CONTINUE THROUGH THE PERIOD AS AN UPPER RIDGE REMAINS ANCHORED OFF THE WEST COAST AND A DEEP TROUGH CONTINUES OVER THE EASTERN UNITED STATES. THE ECMWF AND GFS ARE IN GOOD AGREEMENT THROUGH THE WEEKEND...BUT AT THE END THE TWO MODELS HAVE DIFFERENT IDEAS ABOUT A TROUGH THAT DEVELOPS OFF THE CALIFORNIA COAST. IF A TROUGH DEVELOPS...IT IS NOT EXPECTED TO MOVE INTO THE CENTRAL ROCKIES UNTIL THE MIDDLE OF NEXT WEEK. TEMPERATURES SHOULD GRADUALLY MODERATE THROUGH THE UPCOMING FORECAST PERIOD AS THE NORTHWEST FLOW ALOFT CONTINUES. AVIATION... WINDS HAVE BECOME LIGHT NORTHEAST AT DEN DUE TO WEAK MESOCYCLONE OVER MORGAN COUNTY. GUSTY WEST TO NORTHWEST WINDS CONTINUE AT APA AND BJC. WINDS TO BECOME NORTHWEST AT DEN BY 00Z AS MESOCYCLONE SHIFTS EAST INTO WASHINGTON COUNTY. AFTER 03Z...WINDS SHOULD SHIFT TO THE SOUTHWEST AT DEN AND APA AS DRAINAGE FLOW DEVELOPS WITH SPEEDS AROUND 12 KTS. WINDS TO REMAIN WEST TO NORTHWEST AT BJC THROUGH THE EVENING AND OVERNIGHT...WITH SOME GUSTS TO 40 KTS POSSIBLE AFTER 06Z. ON THURSDAY...WINDS TO BECOME NORTHWEST AND WEAKEN ACROSS THE AREA AFTER 16Z. SOME GUSTS TO 25 KTS WILL BE POSSIBLE AT BJC. VFR TO PREVAIL. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 5 PM MST THURSDAY FOR COZ031-033-034. && $$ SHORT TERM...D-L LONG TERM....DANKERS UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS MIAMI FL
136 AM EST THU JAN 31 2013 .AVIATION... THE LATEST MODEL GUIDANCE SHOWS A NARROW LINE OF SHOWERS ALONG THE FRONTAL BOUNDARY APPROACHING THROUGH THE FIRST FEW HOURS OF THE TAF CYCLE...THROUGH APF BY/AROUND DAYBREAK...THEN THROUGH THE EAST COAST TERMINALS THROUGH THE EARLY/MID MORNING HOURS. WINDS WILL SHIFT FROM THE SOUTH TO NORTHWEST WITH THE FROPA. ALTHOUGH A FEW PERIODS WITH MVFR CIGS CAN`T BE RULED OUT IN AND AROUND ANY SHOWERS ALONG THE FRONT...MOSTLY VFR CONDITIONS ARE EXPECTED. IN THE WAKE OF THE FRONTAL BOUNDARY...A STABLE LOW-LEVEL STATUS DECK WILL LIKELY LINGER THROUGH A GOOD PORTION OF THE DAY BEFORE GRADUALLY CLEARING. && .PREV DISCUSSION... /ISSUED 855 PM EST WED JAN 30 2013/ UPDATE... COLD FRONT MOVING THROUGH THE PANHANDLE THIS EVENING WILL APPROACH SOUTH FLORIDA AFTER MIDNIGHT TONIGHT. LOCAL WRF AND HRRR SHOW A THIN LINE OF SHOWERS APPROACHING THE NORTHWEST PORTIONS OF THE CWA AROUND 09Z TONIGHT...AND THEN THE LINE SLOWLY MOVING THROUGH THE REST OF THE REGION THROUGH THE MORNING HOURS. THE CURRENT POP GRIDS HANDLE THIS WELL...SO NO UPDATES ARE NEEDED. TEMPERATURES TONIGHT WILL BE WARM...WITH LOWS NEAR 60 TO THE LOWER 70S. ALTHOUGH WINDS WILL LIKELY FALL BELOW SCA CRITERION OVER THE LOCAL GULF WATERS THIS EVENING...KEPT THE SCA GOING AS WINDS WILL INCREASE LATE TONIGHT BEHIND THE FRONT. FOR THE ATLANTIC WATERS...WILL CANCEL THE SCA SINCE THE WINDS HAVE FALLEN TO AROUND 10-15 KNOTS AND WINDS ARE NOT EXPECTED TO INCREASE TO SCA CONDITIONS AGAIN UNTIL AFTER 18Z ON THURSDAY. PREV DISCUSSION... /ISSUED 628 PM EST WED JAN 30 2013/ AVIATION...VFR WILL PREVAIL, BUT A FEW SHOWERS/BRIEF MVFR WILL BE POSSIBLE ALONG COLD FRONT EXPECTED TO MOVE ACROSS KAPF AT AROUND SUNRISE, THEN THE EAST COAST TERMINALS BY MID MORNING THU. CURRENT WIND OBS ARE SSE BUT ACARS DATA SHOWS SSW JUST ABOVE THE SFC. VEERED WINDS THROUGH THE NIGHT TO SSW AS FRONT APPROACHES, THEN TURNED WINDS NW BEHIND THE COLD FRONT THU. GUIDANCE SUGGEST CLOUDS LIKELY WILL HANG TOUGH BEHIND THE FRONT FOR THE EAST COAST TERMINALS THROUGHOUT THE DAY THU. BEST PROSPECTS FOR SHOWERS/BRIEF MVFR CIGS LOOK TO BE 10-15Z THU, EXCEPT 06-12Z AT KAPF. THX CWSU MIAMI FOR COORDINATION. /GREGORIA PREV DISCUSSION... /ISSUED 237 PM EST WED JAN 30 2013/ SYNOPSIS... A COLD FRONT WILL MOVE THROUGH SOUTH FLORIDA THURSDAY MORNING...ENDING THE ABOVE NORMAL TEMPERATURES AND BRINGING A SLIGHT CHANCE OF SHOWERS AS IT PASSES. HIGH PRESSURE BUILDS IN FRIDAY THROUGH THE WEEKEND...WITH SLIGHTLY BELOW NORMAL TEMPERATURES RISING TO NEAR SEASONAL AVERAGES BY EARLY NEXT WEEK. SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... BREEZY CONDITIONS IN PLACE THROUGH FLORIDA AS PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE OVER WESTERN ATLANTIC AND SURFACE COLD FRONT MOVING EASTWARD THROUGH THE DEEP SOUTH INCREASES. SOUTH WINDS HAVE GUSTED TO NEAR 30 KTS...JUST BELOW WIND ADVISORY CRITERION. GUSTS MAY DIURNALLY DIMINISH SLIGHTLY...BUT REMAIN HIGH ENOUGH TO PRECLUDE ANY FOG FORMATION TONIGHT. TEMPERATURES AHEAD OF THE FRONT CONTINUE TO BE ABOVE NORMAL...WITH READINGS NEAR 80F ACROSS MOST OF SOUTH FLORIDA. MODELS HAVE TRENDED A BIT SLOWER FOR FROPA FOR SOUTH FLORIDA. THE SFC FRONT LOCATED NEAR KPNS NOW WILL TREK ACROSS THE PANHANDLE THIS EVENING...THEN APPROACH I-4 CORRIDOR OVERNIGHT. IT IS NOT EXPECTED TO INTRUDE ON NORTHWEST SECTIONS OF OUR CWA UNTIL AROUND SUNRISE. THUS...WARM AND FAIRLY BREEZY NIGHT IS IN STORE. MINIMA WILL RANGE FROM AROUND 60F NORTHWEST INTERIOR TO AROUND 70F ATLANTIC METROS. THE COLD FRONT WILL MOVE ACROSS SOUTH FLORIDA DURING THE MORNING...ACCOMPANIED BY A FEW SHOWERS. DYNAMICAL FORCING WILL BE NEGLIGIBLE AND ATMOSPHERE WILL REMAIN FAIRLY STABLE...BUT LOW-LEVEL CONVERGENCE AND DECENT MOISTURE CONTENT SHOULD BE SUFFICIENT FOR SCATTERED ACTIVITY ALONG AND IN VICINITY OF SURFACE BOUNDARY. CAA WILL LAG SEVERAL HOURS BEHIND THE FRONT...SO HIGH TEMPERATURES WILL STILL REACH M/U70S MOST LOCATIONS. SKIES CLEAR AND TEMPERATURES PLUMMET THURSDAY NIGHT...AND DESPITE LACK OF IDEAL RADIATIONAL COOLING CONDITIONS...ADVECTION SHOULD SUPPORT MINIMA REACHING BELOW 50F FOR MUCH OF THE INTERIOR...AND SOME 30S ARE POSSIBLE ACROSS COLLIER...GLADES...AND HENDRY COUNTY. IT APPEARS DRY LOW LEVELS AND NON-ZERO WIND SPEEDS WILL PREVENT ANY FROST...BUT THIS WILL BE MONITORED. AFOREMENTIONED WINDS HOWEVER WILL CREATE WIND CHILL VALUES SOME 5-10 DEGREES LOWER THAN AMBIENT READINGS...LOW ENOUGH TO POSSIBLY REACH ADVISORY THRESHOLDS ACROSS MAINLY GLADES AND HENDRY COUNTIES. TEMPERATURES FRIDAY AND FRIDAY NIGHT WILL BE SLIGHTLY BELOW NORMAL...WITH L70S FOR MAXIMA AND 40S INLAND/50S COASTAL FOR MINIMA. HIGH PRESSURE BUILDING SOUTH WILL KEEP SKIES CLEAR...AND NORTH WINDS WILL GRADUALLY BECOME NORTHEAST AND BECOME QUITE LIGHT OVERNIGHT FRIDAY. TEMPERATURES ATTM APPEAR JUST ABOVE VALUES THAT WOULD CAUSE FROST CONCERN AND LACK OF WIND SHOULD PRECLUDE ANY WIND CHILL CONCERNS. LONG TERM /SATURDAY THROUGH WEDNESDAY/... THE EXTENDED PERIOD FROM THIS WEEKEND INTO THE MIDDLE OF NEXT WEEK LOOKS UNEVENTFUL AND DRY AS SEVERAL MID LEVEL TROUGHS MOVE ACROSS THE NORTHERN STATES MAINTAINING A WEST TO NORTHWEST FLOW OF DRY AIR OVER THE FLORIDA PENINSULA AND KEEPING THE MID LEVEL RIDGE SUPPRESSED TO OUR SOUTHEAST. AS THE TROUGHS MOVE TO OUR NORTH, THIS WILL ALSO REINFORCE THE SURFACE RIDGING ACROSS THE SOUTHEAST STATES WHICH IN TURN WILL KEEP THE TEMPERATURES CLOSE TO OR SLIGHTLY BELOW CLIMATOLOGICAL AVERAGES FOR THE BEGINNING OF FEBRUARY. AVIATION... GUSTY SOUTHEASTERLY WINDS WILL CONTINUE THROUGH THE TAF PERIOD AT ALL SITES. FROPA IS STILL EXPECTED ACROSS THE EAST COAST TERMINALS BETWEEN 10Z-13Z ACCOMPANIED BY SCATTERED SHOWERS. BRIEF PERIODS OF MVFR CIGS WILL LIKELY ACCOMPANY ANY SHOWER ACTIVITY BUT SHOULD NOT BE LONG ENOUGH TO PREVAIL IN THE TAF. WINDS WILL TURN AROUND TO THE NORTHWEST BEHIND THE FRONT AND REMAIN AT AROUND 10 KNOTS. MARINE... WINDS NEAR 20 KTS WITH SOUTHERLY GUSTS TO NEAR 30 KTS WARRANTED ISSUANCE OF SMALL CRAFT ADVISORY EARLY TODAY...AND THIS WILL REMAIN IN EFFECT FOR ALL MARINE ZONES OVERNIGHT. STRONG WINDS BEING INDUCED BY TIGHT PRESSURE GRADIENT IN ADVANCE OF QUICK- MOVING COLD FRONT. THIS FRONT WILL PASS THROUGH EARLY FRIDAY...WITH NORTH WINDS LIKELY EXCEEDING ADVISORY THRESHOLD BEHIND IT. STRONG WINDS AND BUILDING SEAS WILL IMPACT THE WATERS THURSDAY NIGHT THROUGH AT LEAST FRIDAY...BEFORE SUBSIDING AS HIGH PRESSURE BUILDS OVERHEAD. FIRE WEATHER... NO FIRE WEATHER CONCERNS TODAY. A COLD FRONT WILL RACE THROUGH SOUTH FLORIDA THURSDAY MORNING...WITH MUCH DRIER AIR MOVING IN IN ITS WAKE. RELATIVE HUMIDITY VALUES MAY DROP TO NEAR 35 PERCENT THURSDAY AFTERNOON ACROSS GLADES AND HENDRY COUNTIES AND NORTH WINDS WILL BE 10 TO 15 MPH OR HIGHER. FORECAST CONDITIONS DONT SUPPORT ISSUANCE OF FIRE WEATHER WATCH...BUT A FIRE DANGER STATEMENT HAS BEEN ISSUED THURSDAY. RELATIVE HUMIDITY WILL BE VERY LOW FRIDAY...BUT WINDS WILL SUBSIDE A BIT. STILL...FIRE WEATHER HEADLINES ARE LIKELY ON FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 75 52 71 54 / 30 - 0 0 FORT LAUDERDALE 79 56 72 60 / 30 - 0 0 MIAMI 80 57 72 59 / 20 - 0 0 NAPLES 71 46 71 49 / 20 - 0 0 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$ DISCUSSION/MARINE/FIRE...30/KOB AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1156 PM EST WED JAN 30 2013 .UPDATE... ISSUED AT 1012 PM EST WED JAN 30 2013 ALL HEADLINES THAT END THIS EVENING HAVE BEEN ALLOWED TO EXPIRE AS SCHEDULED. ATTENTION NOW TURNS TO LAKE ENHANCED/LAKE EFFECT SNOW AS COLDER AIR CONTINUES TO FLOW INTO THE AREA BEHIND DEPARTING STORM SYSTEM. KMQT RADAR HAS SHOWN A NICE EXPANSION OF HVY SNOW BANDS OFF LAKE SUPERIOR THIS EVENING UNDER LINGERING DEEP MOISTURE/CAA...AND VAD WIND PROFILE SHOWS NEARLY UNIDIRECTIONAL NORTHERLY WINDS TO 11KFT MSL. THERE ARE CONFLICTING SIGNALS ON HOW MUCH THE WIND MAY BACK OVERNIGHT AS LOCAL HIGH RES-WRF MAINTAINS A MORE NRLY WIND INTO NCNTRL UPPER MI WHILE NAM BACKS WIND MORE NW. GIVEN TRENDS IN HRLY RUC RAPID REFRESH RUNS TO SLOW THE BACKING...OPTED TO EXTEND WARNING FOR MARQUETTE COUNTY UNTIL 11Z. WITH RATHER PERSISTENT HVY SNOW OCCURRING AT THE OFFICE THIS EVENING AND RADAR IMAGERY SHOWING EXPANSION OF HVY SNOW BANDS...WOULD NOT BE SURPRISED TO SEE SOME LOCALIZED ACCUMULATIONS OVER 1 FOOT DURING THE NIGHT IN THE HIGHER TERRAIN BETWEEN BIG BAY...NEGAUNEE...GWINN AND SKANDIA. THIS HVY SNOW WILL ALSO TARGET WRN ALGER COUNTY WEST OF SHINGLETON. WHILE WARNING FOR ALGER/LUCE/NRN SCHOOLCRAFT ONLY GOES TO 12Z...WILL LET MID SHIFT TAKE A LOOK AT REPLACEMENT WITH A LONGER DURATION LAKE EFFECT SNOW ADVY OR WARNING FOR THAT AREA. TO THE W...NO CHANGES WERE MADE TO THE GOGEBIC/ONTONAGON ADVY. OVER THE KEWEENAW...COLD AIR WILL PUSH THE DGZ DOWN TO NEAR THE SFC... RESULTING IN SMALL SNOWFLAKES THAT ARE VERY EFFECTIVE AT REDUCING VIS. WHILE ACCUMULATIONS WILL PROBABLY ONLY BE IN THE 2-4 INCH RANGE/12HRS AT MOST LOCATIONS...VERY LOW VIS DURING -SHSN ALONG WITH OCNL BLSN SUGGEST AN ADVY HEADLINE IS WARRANTED FOR KEWEENAW/NRN HOUGHTON AS DRIVING WILL BE DIFFICULT AT TIMES. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 441 PM EST WED JAN 30 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM HUDSON BAY AND NW ONTARIO THROUGH MN/IA INTO ERN OK. THE POTENT SHORTWAVE TROUGH OVER SW WI AND ASSOCIATED DEFORMATION ZONE CONTINUED TO SUPPORT A HEAVY SNOW BAND FROM ERN WI INTO THE E HALF OF UPPER MI. LIGHTER SNOW WAS OBSERVED OVER THE WEST HALF OF UPPER MI. SNOW TOTALS OF AROUND 6 INCHES WERE OBSERVED BY 21Z FROM THE NWS MQT OFFICE TO MNM...GLADSTONE AND MANISTIQUE. A TIGHT GRADIENT BTWN THE 987 MB LOW OVER SRN LOWER MI AND ARCTIC HIGH PRES BUILDING INTO THE PLAINS HAS RESULTED IN GALES ACROSS LAKE SUPERIOR AND GUSTY N WINDS TO 30 MPH OVER MOST OF THE CWA. TONIGHT AND THURSDAY...THE HEAVY SNOW BAND WHICH CORRELATED WELL WITH NAM/RUC 700-600 MB FGEN IS EXPECTED TO SHIF QUICKLY TO THE NORTHEAST THIS EVENING LEAVING MAINLY LIGHT SNOW THAT WILL DIMINISH BTWN 00Z-03Z. HOWEVER...COLDER AIR MOVING IN ON THE STRONG N WINDS COMBINED WITH 850 MB TEMPS TO AROUND -15C WILL CONTINUE TO SUPPORT LCLY HIGHER SNOWFALL RATES N CNTRL...ESPECIALLY VCTY MARQUETTE THIS EVENING WITH CYCLONIC LOW LEVEL 340-350 WIND DIRECTION NEAR THE SHORE. FAVORABLE UPSLOPE NRLY FLOW INTO THE FAR WEST SHOULD ALSO BRING INCREASING LES INTO IWD. RADAR TRENDS AND MODELS SUGGEST ADDITIONAL SYNOPTIC SNOW POTENTIAL IN THE 1 TO 3 INCH RANGE BTWN 21Z- 03Z. HOWEVER AREAS WITH LAKE CONTRIBUTION COULD SEE ANOTHER 3 TO 6 INCHES THROUGH 12Z/THU. AS THE STRONGER SYNOPTIC FORCING WITH THE SHRTWV MOVES OUT THIS EVENING...HEADLINES ARE SET TO EXPIRE BY AROUND 03Z OVER THE S CWA. A TRANSISTION TO LAKE EFFECT SNOW WILL CONTINUE OVERNIGHT WITH FAVORABLE CONDITION PERSISTING INTO THURSDAY. ANOTHER TRAILING SHRTWV SLIDING SE INTO THE UPPER LAKES WILL MAINTAIN 850-700 MB MOISTURE AND INVERSION HEIGHTS AOA 10K FT. WITH THE WINDS BACKING SLIGHTLY TO 340-330 THE HEAVIER LES WILL CONTINUE TO FOCUS INTO THE FAR WEST AND TO AREAS EAST OF MARQUETTE. 850 MB TEMPS FALLING TO AROUND -20C MAY SHRINK THE DGZ LAYER INTO THE 1K-3K RANGE BUT STILL SHOULD BE SUFFICIENT FOR LSR VALUES CLOSE TO 25/1. ADDITIONAL SNOWFALL AMOUNTS OF 3 TO 7 INCHES ARE POSSIBLE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 441 PM EST WED JAN 30 2013 MODELS ARE IN GOOD GENERAL AGREEMENT THROUGH THE EXTENDED WITH DEEP UPPER TROUGH STARTING THE PERIOD FRI AND GRADUALLY BREAKING DOWN AND SHIFTING WEST THROUGH NEXT WED...AS AN UPPER RIDGE MOVES INTO THE WRN CONUS. GOOD NW WIND LES WILL BE ONGOING INTO THU NIGHT GIVEN NW LOW LEVEL FLOW...AMPLE MOISTURE AND 825MB INVERSION TOP TEMPS AROUND -25C. LATE THU NIGHT AND FRI...A SFC HIGH WILL MOVE S OF THE CWA WHILE A SHORTWAVE TROUGH DIVES IN FROM THE NW FORMING A MESO-LOW OVER ERN LAKE SUPERIOR LATE FRI. THIS TURNS THE NW WINDS WLY BY FRI AFTERNOON...FOCUSING LES OVER THE KEWEENAW AND FAR NE UPPER MI. PRIOR WIND SHIFT...THE BEST LES WILL BE FOCUSED OVER ONTONAGON AND GOGEBIC COUNTIES AND OVER ERN UPPER MI FROM MUNISING TO GRAND MARAIS. LES SHOULD INITIALLY WEAKEN SOME LATE THU NIGHT AS RIDGING MOVES INTO THE AREA...BUT WILL GET A BOOST FROM THE SHORTWAVE LATER ON FRIDAY. THERE IS ALREADY A LES ADVISORY FOR ONTONAGON/GOGEBIC COUNTIES THROUGH THU NIGHT...AND THAT STILL LOOKS FINE. BUT WILL LIKELY ALSO NEED HEADLINES FOR THE ERN U.P. THU NIGHT INTO FRI. THE KEWEENAW MAY ALSO NEED HEADLINES FRI INTO FRI NIGHT. WILL NOT ISSUE ANY NEW HEADLINES AT THIS POINT GIVEN HEADLINES ALREADY IN EFFECT OVER THE ERN U.P. AND SOME UNCERTAINTY AS TO THE RESIDENCE TIME AND INTENSITY OF ANY STRONGER BANDS THAT MOVE ACROSS THE KEWEENAW. THU NIGHT THROUGH FRI NIGHT LOOKS TO BE THE COLDEST PERIOD OF THE NEXT WEEK. LOWS THU NIGHT AND FRI NIGHT LOOKS TO FALL TO THE TEENS BELOW ZERO WITH WIND CHILLS TO -35F OVER PARTS OF THE INTERIOR. HIGHS ON FRI LOOK TO BE AROUND ZERO OVER THE INTERIOR W...AND IN THE LOW TEENS ABOVE ZERO E. WIND CHILL VALUES ARE CURRENTLY FORECAST TO BE IN TEENS BELOW ZERO AT THE WARMEST FRI AFTERNOON OVER THE INTERIOR W...AND IN THE SINGLE DIGITS BELOW ZERO E. WILL LIKELY NEED SOME WIND CHILL ADVISORY HEADLINES UP WHERE THERE ARE NO OTHER WINTER WX HEADLINES. MODELS IN RELATIVELY GOOD AGREEMENT WITH A CLIPPER SHORTWAVE MOVING THROUGH LATE SAT INTO EARLY SAT NIGHT...BUT ONLY MINOR SYNOPTIC SNOW ACCUMULATIONS AND INCREASED NW WIND LES ARE EXPECTED TO RESULT FROM THE SYSTEM. SFC RIDGING MOVES OVER ON SUN AHEAD OF THE NEXT...STRONGER...CLIPPER SYSTEM THAT MODEL DEPICT MOVING THROUGH. ALTHOUGH MODELS SEEM TO AGREE FAIRLY WELL ON THE OVERALL TRACK AND INTENSITY OF THE SYSTEM...THE 00Z/30 ECMWF IS 6-12 HOURS FASTER THAN THE 12Z/30 GFS. SEVERAL INCHES OF SNOW MAY RESULT AREA WIDE FROM THIS SYSTEM. MODELS THEN INDICATE...WITH GREATER UNCERTAINTY...ANOTHER CLIPPER SYSTEM MOVING THROUGH SOMETIME MIDWEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1155 PM EST WED JAN 30 2013 AT KIWD...LAKE EFFECT -SHSN WILL INCREASE OVERNIGHT AS COLDER AIR FLOWS INTO THE AREA AND LOW-LEVEL WINDS BECOME MORE CONVERGENT INTO WRN UPPER MI. AS A RESULT...IFR CONDITIONS SHOULD GENERALLY PREVAIL AT KIWD THRU TODAY. SOME IMPROVEMENT IS POSSIBLE THIS EVENING AS WINDS BEGIN TO BACK...POSSIBLY SHIFTING -SHSN N OF KIWD. AT KCMX...IFR CONDITIONS SHOULD PREVAIL OVERNIGHT AS LAKE EFFECT -SHSN CONTINUE UNDER INCREASINGLY COLDER AIR MASS. WITH THE COLDER AIR...SNOWFLAKE SIZE WILL BECOME SMALLER AND VERY EFFECTIVE AT KEEPING VIS LOW. COMBINATION OF SNOW AND SOME BLSN WILL LIKELY RESULT IN LIFR CONDITIONS FOR MUCH OF THE DAY INTO THE EVENING AT KCMX. AT KSAW... LAKE EFFECT SHSN UNDER NORTHERLY WINDS SHOULD LEAD TO IFR/LIFR CONDITIONS FOR THE NEXT SEVERAL HRS. AS WINDS BACK AND PUSH HEAVIER LAKE EFFECT SHSN TO THE E...EXPECT IMPROVEMENT TO MVFR EARLY IN THE MORNING. MVFR SHOULD THEN PREVAIL FOR THE REMAINDER OF THE FCST PERIOD. AS IS TYPICAL FOR LAKE EFFECT SNOW...EXPECT VIS AT ALL SITES TO BE HIGHLY VARIABLE AT TIMES AS SNOW BANDS MOVE ACROSS THE AREA. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 441 PM EST WED JAN 30 2013 N TO NW GALES OF 35 TO 40 KNOTS WILL CONTINUE THROUGH MUCH OF TONIGHT...WITH A FEW GALE FORCE GUSTS TO 35 KNOTS LINGERING E THROUGH THURSDAY. LOW PRESSURE OVER LOWER MICHIGAN WILL LIFT NORTHEAST INTO ONTARIO AND QUEBEC TONIGHT. WITH PLENTY OF COLD AIR SINKING IN BEHIND THE LOW AND STRONG WINDS...HEAVY FREEZING SPRAY WILL PREVAIL THROUGH THURSDAY NIGHT...AND MAY LINGER OVER THE FAR EAST THROUGH FRIDAY NIGHT. A TROUGH WILL LINGER OVER LAKE SUPERIOR THROUGH THURSDAY...AS STRONG HIGH PRESSURE SINKS ACROSS THE PLAINS STATES. EXPECT THE HIGH PRESSURE SYSTEM TO WEAKEN SLIGHTLY OVER THE MISSISSIPPI VALLEY FRIDAY...WHILE PUSHING A RIDGE ACROSS WESTERN LAKE SUPERIOR. WEAK LOW PRESSURE WILL LINGER ACROSS EASTERN LAKE SUPERIOR THROUGH SATURDAY. ANOTHER LOW PRESSURE TROUGH WILL SINK SOUTHWARD FROM MANITOBA INTO THE UPPER GREAT LAKES SATURDAY EVENING...BEFORE MOVING INTO THE LOWER GREAT LAKES DURING THE DAY SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>003-009. WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MIZ005. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR LSZ265>267. GALE WARNING UNTIL 4 AM EST THURSDAY FOR LSZ264>267. HEAVY FREEZING SPRAY WARNING UNTIL 1 AM EST /MIDNIGHT CST/ SATURDAY FOR LSZ162-263-264. LAKE MICHIGAN... NONE. && $$ UPDATE...ROLFSON SHORT TERM...JLB LONG TERM...TITUS AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1152 PM EST WED JAN 30 2013 .AVIATION... //DISCUSSION... GUSTY WESTERLY WINDS WILL PERSIST THROUGH THE MORNING AS ARCTIC AIR CONTINUES TO POUR INTO THE FORECAST AREA. STEEPENING LOW LEVEL LAPSE RATES COURTESY OF THE COLD AIR ADVECTION WILL BRING SOME STRONG WIND GUSTS DOWN TO THE SURFACE...LIKELY TOPPING 30 KNOTS AT TIMES THIS MORNING. THE WINDS WILL DIMINISH SLIGHTLY THIS AFTERNOON AS THE GRADIENT RELAXES. WIDESPREAD MVFR CIGS WILL SLOWLY LIFT DURING THE COURSE OF THE TAF PERIOD AS THE COLD AIR ADVECTION LIFTS INVERSION HEIGHTS. WHILE SNOW SHOWERS WILL REMAIN RATHER LIGHT OVERNIGHT...SOME INCREASE IN INTENSITY IS EXPECTED AFTER 12Z...PRIMARILY FROM PTK SOUTH. WITH STILL SOME UNCERTAINTY AS TO HOW THE LAKE BANDS WILL SET UP...WILL CONTINUE WITH MVFR TYPE CIGS/VSBY IN THE SNOW SHOWERS THROUGH THE MORNING AT THIS TIME. FOR DTW...EXPECT WESTERLY WIND GUSTS AROUND OR ABOVE 30 KNOTS THROUGH THE MORNING AND INTO THE AFTERNOON. THERE IS A POTENTIAL FOR ENHANCED SNOW SHOWERS OFF LAKE MICHIGAN TO IMPACT THE AIRPORT AFTER 12Z. GIVEN THE LOW CONFIDENCE AT THIS STAGE IN THE FORECAST...WILL HOLD OFF ON INTRODUCING IFR TYPE CONDITIONS AT THIS TIME. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILING BELOW 5000 FT THROUGH THE TAF PERIOD. * HIGH CONFIDENCE WESTERLY WIND GUSTS WILL EXCEED 28 KNOTS BETWEEN 06Z AND 19Z THURS. && .PREV DISCUSSION...ISSUED 1007 PM EST WED JAN 30 2013 UPDATE... THE WIDESPREAD RAIN WHICH HAS BEEN ROLLING ACROSS THE FORECAST AREA THIS EVENING WILL QUICKLY LIFT OFF TO THE NORTHEAST OVER THE NEXT COUPLE OF HOURS. RECENT OBSERVATIONS INDICATE THE BULK OF THESE HEAVIER SHOWERS WILL BE OFF TO THE EAST PRIOR TO THE ARRIVAL OF THE ARCTIC AIR AND CHANGE OVER TO SNOW. NONETHELESS...THE ADVANCE OF DEEPER MOISTURE WITHIN THE MID LEVEL TROUGH AXIS WILL ROTATE THROUGH THE FORECAST AREA OVERNIGHT PROVIDING SOME LIGHT SNOW SHOWERS TO THE AREA. THE RESPONSE OFF LAKE MI FROM THE AGGRESSIVE PUSH OF COLD AIR TONIGHT WILL ALSO BE QUITE GOOD. LAKE ENHANCED SNOW SHOWERS SHOULD SUPPORT SOME HIGHER POPS ACROSS THE SOUTHERN HALF OF THE FORECAST AREA OVERNIGHT. THE HIGHER INTENSITY SNOW SHOWERS SHOULD HOLD OFF UNTIL AFTER DAYBREAK...SO SNOW ACCUMS TONIGHT SHOULD BE MINOR. THE ARCTIC FRONT IS NOW ON THE DOORSTEP OF THE FORECAST AREA AND WILL TRACK EAST OF THE AREA SHORTLY AFTER MIDNIGHT. OVER THE NEXT TWO HOURS...TEMPS WILL RAPIDLY DROP BELOW FREEZING. WHILE THE WINDS WILL HELP DRY THE ROAD SURFACES A BIT...EXPECT THERE WILL SOME SLICK ROADS OVERNIGHT. THE SURFACE LOW NOW OVER LAKE HURON WILL CONTINUE TO DEEPEN AS IT PULLS NORTHEAST OF THE REGION OVERNIGHT. MEANWHILE...STRONG COLD AIR ADVECTION WILL STEEPEN THE LOW LEVEL LAPSE RATES. THE MOST RECENT RAP AND 18Z NAM CONTINUE TO SHOW A SOLID 40-45 KTS IN THE MIXED LAYER OVERNIGHT /ESPECIALLY ACROSS THE EASTERN PORTIONS OF THE FORECAST AREA/. THUS THE CURRENT WIND ADVISORY HEADLINE FOR MUCH OF THE FORECAST AREA WILL REMAIN IN EFFECT. PREV DISCUSSION...ISSUED 345 PM EST WED JAN 30 2013 SHORT TERM... TONIGHT THERE ARE SEVERAL CONCERNS ASSOCIATED WITH THE FORECAST TONIGHT FOR CONDITIONS THAT WILL HAVE AT LEAST MODERATE IMPACT AROUND SE MICHIGAN. THE ADVISORY FOR HIGH WIND WILL BE MOST SIGNIFICANT FOLLOWED CLOSELY BY THE COMBINATION OF FALLING TEMPERATURES AND RAIN CHANGING TO SNOW ADDING A LAYER OF COMPLEXITY. ALL OF THIS WILL BE DRIVEN BY A WAVE OF LOW PRESSURE THAT WILL MOVE FROM SOUTHWEST LOWER MICHIGAN DURING THE AFTERNOON, THROUGH CENTRAL LAKE HURON AND INTO EASTERN ONTARIO TONIGHT, ALL THE WHILE DEEPENING AS IT GOES. THE DEEPENING TREND OF THE LOW AS IT PASSES TO OUR EAST WILL BE FOSTERED BY THE DYNAMICS OF THE NEGATIVE TILT SHORT WAVE THAT IS ALREADY TAKING SHAPE IN SATELLITE IMAGERY DURING THE AFTERNOON. INCREASING SURFACE WIND TRAILING THE LOW IS ALSO OBSERVED TO PRODUCE WIND GUSTS AROUND 30 KNOTS OVER THE MIDWEST AT PRESS TIME. WITH THE SYSTEM ALREADY OFF TO A GOOD START, CONFIDENCE IS INCREASED IN THE DEPICTIONS SHOWN IN THE ARRAY OF 12Z MODEL OUTPUT THAT BUILD A STRONG WESTERLY WIND FIELD OVER SE MICHIGAN BY MIDNIGHT. SOME GUSTINESS IS EXPECTED IN THE WARMER AIR AHEAD OF THE FRONT, ASSOCIATED WITH THE LOW LEVEL JET, AND WITH THE ISALLOBARIC COMPONENT OF FORCING IMMEDIATELY BEHIND THE FRONT, BUT THESE ELEMENTS ARE NOT EXPECTED TO EXCEED ADVISORY CRITERIA. THAT IS INSTEAD LIKELY TO OCCUR TOWARD MIDNIGHT THROUGH WEDNESDAY MORNING AS DYNAMICALLY DRIVEN MID LEVEL SUBSIDENCE AND STRONG COLD ADVECTION HELP DIRECT A 45-50 KNOT WIND FIELD TOWARD THE SURFACE FROM THE 850 TO 700 MB LAYER. MODEL CROSS SECTIONS INDICATE NEARLY 10 DEGREES(K) OF THETA SURFACES INTERSECTING THE GROUND DURING THE INTERVAL OF ISENTROPIC DECENT. MODEL SOUNDINGS THEN SHOW THE MIXED LAYER DEEPENING TO NEAR THE 800 MB LEVEL FOR THE LATE OVERNIGHT HOURS WITH 45 KNOTS OF WIND AVAILABLE FOR CONTRIBUTION TO SURFACE WIND GUSTS. AREAL COVERAGE WILL BE GREATEST ALONG AND SOUTH OF INTERSTATE 69 WITH THE THUMB VULNERABLE DUE TO WIND GUSTS MOVING OFF OF SAGINAW BAY. PLAN TO LEAVE THE TRI CITIES OUT OF THE HEADLINE FOR NOW. THE STRONG WINDS WILL PULL DRAMATICALLY COLDER AIR INTO SE MICHIGAN DURING THE NIGHT WITH READINGS DROPPING INTO THE UPPER TEENS IN THE TRI CITIES BY SUNRISE TO THE MID 20S METRO DETROIT. THE BULK OF PRECIPITATION WILL COME IN THE FORM OF RAIN SHOWERS THROUGH MID EVENING WITH THE CHANGE TO SNOW AT THE VERY TAIL END FOR JUST A DUSTING OF ACCUMULATION IN THE DETROIT AREA AND UP TO AN INCH IN THE NORTHERN THUMB. LONG TERM... LAKE MICHIGAN LAKE EFFECT MACHINE WILL BE CRANKING UP THURSDAY...ENHANCED BY A GOOD UPPER LEVEL WAVE/MID LEVEL COLD POOL SWINGING THROUGH THE MIDWEST/WESTERN OHIO VALLEY TOMORROW AFTERNOON. STRONG WESTERLY WINDS (35-45 MPH) IN WAKE OF THE QUICKLY DEEPENING LOW PRESSURE WILL USHER IN SUFFICIENTLY COLD AIRMASS...UPPER NEGATIVE TEENS AT 850 MB OVER LOWER MICHIGAN...BUT LOWER NEGATIVE 20S SWINGING THROUGH THE WESTERN OHIO VALLEY. 700 MB COLD POOL OF -28 TO -30 C OVER SOUTHERN LOWER MICHIGAN THURSDAY EVENING WITH MODEST 925-850 MB LIFT/CONVERGENCE EXTENDING INTO SOUTHEAST MICHIGAN...AND PLANNING ON CARRYING NUMEROUS POPS..ALTHOUGH FOCUS OF ACTIVITY WILL LIKELY SHIFT FROM NORTH TO SOUTH THROUGH THE NIGHT AS MODEST 850 THETA-E RIDGE SETTLES SOUTH. WITH A HIGH FLUFF FACTOR TO SNOW...20+:1 RATIOS...A QUICK INCH OR TWO IS LIKELY IN SPOTS AS 925-850 MB PROFILES REMAIN IN THE DENDRITIC ZONE GROWTH REGION. HEART OF THE COLD AIR/THERMAL TROUGH AXIS WILL BE IN PLACE FOR FRIDAY...WITH 850 MB TEMPS HOVERING AROUND -20 C ON FRIDAY...AND HAVE NO COMPLAINTS WITH INHERITED MAXES IN THE UPPER TEENS TO AROUND 20...IN LINE WITH LATEST GUIDANCE. A SURFACE RIDGE WILL ATTEMPT TO MOVE IN FRIDAY NIGHT. IF THIS IS SUFFICIENT IN CLEARING OUT THE LOW CLOUDS...LOOKING AT MINS AT OR BELOW ZERO FOR MUCH OF THE AREA WITH EXPECTED FRESH SNOW COVER. CONFIDENCE IS NOT HIGH...AND WILL HAVE TO PLAY IT CONSERVATIVE (LOW/MID SINGLE NUMBERS) AS THERE IS ALSO LURKING WARM ADVECTION CLOUDS STREAMING INTO THE WESTERN GREAT LAKES. POLAR VORTEX LOOKS TO BE ANCHORED OVER/NEAR FAR NORTHERN HUDSON BAY/SOUTHAMPTON ISLAND OVER THE NEXT SEVERAL DAYS...AND THIS WILL MAINTAIN THE UPPER LEVEL NORTHWEST FLOW WITH A COUPLE SHORTWAVES/CLIPPER SYSTEMS TO IMPACT OR TRACK NEAR SOUTHERN LOWER MICHIGAN. WITH MOISTURE AT A PREMIUM...USUALLY NEED TO BE ON THE NORTHEAST FLANK OF THE LOW (WARM ADVECTION/ISENTROPIC ASCENT/MOISTURE CONVERGENCE) TO GET ANY SUBSTANTIAL SNOWFALL. BEST GUESS AT TIMING OF SYSTEMS WOULD BE SATURDAY NIGHT AND THEN AGAIN ON MONDAY. 12Z TRENDS OF EURO/GFS SUGGEST SATURDAY NIGHTS SYSTEM WILL TRACK JUST A BIT TOO FAR SOUTH...WITH MONDAYS SYSTEM/TRACK MORE FAVORABLE. THE EARLY NEXT WEEK LOW WILL ALSO HAVE A BIT MORE OF A PACIFIC ORIGIN...AND THUS A BIT MORE MOISTURE. STILL TOO EARLY TO GET A GOOD HANDLE OF THE GULF OF ALASKA ENERGY AND EVENTUAL BREAKDOWN/SPILLING OVER INTO THE CONUS HOWEVER. MARINE... A POWERFUL COLD FRONT WILL SWEEP THROUGH LAKE HURON AND LOWER MICHIGAN TONIGHT. INCREASING NORTHWEST WINDS AND A SURGE OF COLDER AIR WILL BRING GALES TO ALL MARINE AREAS. CONSIDERABLE INSTABILITY ACROSS THE LONG FETCH IN NORTHWEST FLOW OF THE OPEN WATERS WILL MAINTAIN A LONGER PERIOD OF GALES FOR CENTRAL PORTIONS OF THE LAKE THROUGH THURSDAY. THE COMBINATION OF THE STRONG WINDS, ARCTIC AIR, AND COLDER WATER TEMPERATURE WILL LEAD TO HEAVY FREEZING SPRAY ACROSS NORTHERN SECTIONS OF LAKE HURON DURING THIS TIME. HIGH PRESSURE WILL SETTLE OVER THE OHIO VALLEY AND BRING IMPROVED CONDITIONS BY FRIDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WIND ADVISORY...MIZ049-MIZ054-MIZ055-MIZ061-MIZ062-MIZ063-MIZ068- MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-MIZ083...UNTIL NOON THURSDAY. LAKE HURON... GALE WARNING...LHZ361...UNTIL NOON THURSDAY. HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362...UNTIL 7 PM THURSDAY. GALE WARNING...LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...UNTIL 7 PM THURSDAY. GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...UNTIL 4 PM THURSDAY. LAKE ST CLAIR... GALE WARNING...UNTIL 4 PM THURSDAY. MI WATERS OF LAKE ERIE... GALE WARNING...UNTIL 4 PM THURSDAY. && $$ AVIATION.....SC UPDATE.......SC SHORT TERM...BT LONG TERM....SF MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1013 PM EST WED JAN 30 2013 .UPDATE... ISSUED AT 1012 PM EST WED JAN 30 2013 ALL HEADLINES THAT END THIS EVENING HAVE BEEN ALLOWED TO EXPIRE AS SCHEDULED. ATTENTION NOW TURNS TO LAKE ENHANCED/LAKE EFFECT SNOW AS COLDER AIR CONTINUES TO FLOW INTO THE AREA BEHIND DEPARTING STORM SYSTEM. KMQT RADAR HAS SHOWN A NICE EXPANSION OF HVY SNOW BANDS OFF LAKE SUPERIOR THIS EVENING UNDER LINGERING DEEP MOISTURE/CAA...AND VAD WIND PROFILE SHOWS NEARLY UNIDIRECTIONAL NORTHERLY WINDS TO 11KFT MSL. THERE ARE CONFLICTING SIGNALS ON HOW MUCH THE WIND MAY BACK OVERNIGHT AS LOCAL HIGH RES-WRF MAINTAINS A MORE NRLY WIND INTO NCNTRL UPPER MI WHILE NAM BACKS WIND MORE NW. GIVEN TRENDS IN HRLY RUC RAPID REFRESH RUNS TO SLOW THE BACKING...OPTED TO EXTEND WARNING FOR MARQUETTE COUNTY UNTIL 11Z. WITH RATHER PERSISTENT HVY SNOW OCCURRING AT THE OFFICE THIS EVENING AND RADAR IMAGERY SHOWING EXPANSION OF HVY SNOW BANDS...WOULD NOT BE SURPRISED TO SEE SOME LOCALIZED ACCUMULATIONS OVER 1 FOOT DURING THE NIGHT IN THE HIGHER TERRAIN BETWEEN BIG BAY...NEGAUNEE...GWINN AND SKANDIA. THIS HVY SNOW WILL ALSO TARGET WRN ALGER COUNTY WEST OF SHINGLETON. WHILE WARNING FOR ALGER/LUCE/NRN SCHOOLCRAFT ONLY GOES TO 12Z...WILL LET MID SHIFT TAKE A LOOK AT REPLACEMENT WITH A LONGER DURATION LAKE EFFECT SNOW ADVY OR WARNING FOR THAT AREA. TO THE W...NO CHANGES WERE MADE TO THE GOGEBIC/ONTONAGON ADVY. OVER THE KEWEENAW...COLD AIR WILL PUSH THE DGZ DOWN TO NEAR THE SFC... RESULTING IN SMALL SNOWFLAKES THAT ARE VERY EFFECTIVE AT REDUCING VIS. WHILE ACCUMULATIONS WILL PROBABLY ONLY BE IN THE 2-4 INCH RANGE/12HRS AT MOST LOCATIONS...VERY LOW VIS DURING -SHSN ALONG WITH OCNL BLSN SUGGEST AN ADVY HEADLINE IS WARRANTED FOR KEWEENAW/NRN HOUGHTON AS DRIVING WILL BE DIFFICULT AT TIMES. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 441 PM EST WED JAN 30 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM HUDSON BAY AND NW ONTARIO THROUGH MN/IA INTO ERN OK. THE POTENT SHORTWAVE TROUGH OVER SW WI AND ASSOCIATED DEFORMATION ZONE CONTINUED TO SUPPORT A HEAVY SNOW BAND FROM ERN WI INTO THE E HALF OF UPPER MI. LIGHTER SNOW WAS OBSERVED OVER THE WEST HALF OF UPPER MI. SNOW TOTALS OF AROUND 6 INCHES WERE OBSERVED BY 21Z FROM THE NWS MQT OFFICE TO MNM...GLADSTONE AND MANISTIQUE. A TIGHT GRADIENT BTWN THE 987 MB LOW OVER SRN LOWER MI AND ARCTIC HIGH PRES BUILDING INTO THE PLAINS HAS RESULTED IN GALES ACROSS LAKE SUPERIOR AND GUSTY N WINDS TO 30 MPH OVER MOST OF THE CWA. TONIGHT AND THURSDAY...THE HEAVY SNOW BAND WHICH CORRELATED WELL WITH NAM/RUC 700-600 MB FGEN IS EXPECTED TO SHIF QUICKLY TO THE NORTHEAST THIS EVENING LEAVING MAINLY LIGHT SNOW THAT WILL DIMINISH BTWN 00Z-03Z. HOWEVER...COLDER AIR MOVING IN ON THE STRONG N WINDS COMBINED WITH 850 MB TEMPS TO AROUND -15C WILL CONTINUE TO SUPPORT LCLY HIGHER SNOWFALL RATES N CNTRL...ESPECIALLY VCTY MARQUETTE THIS EVENING WITH CYCLONIC LOW LEVEL 340-350 WIND DIRECTION NEAR THE SHORE. FAVORABLE UPSLOPE NRLY FLOW INTO THE FAR WEST SHOULD ALSO BRING INCREASING LES INTO IWD. RADAR TRENDS AND MODELS SUGGEST ADDITIONAL SYNOPTIC SNOW POTENTIAL IN THE 1 TO 3 INCH RANGE BTWN 21Z- 03Z. HOWEVER AREAS WITH LAKE CONTRIBUTION COULD SEE ANOTHER 3 TO 6 INCHES THROUGH 12Z/THU. AS THE STRONGER SYNOPTIC FORCING WITH THE SHRTWV MOVES OUT THIS EVENING...HEADLINES ARE SET TO EXPIRE BY AROUND 03Z OVER THE S CWA. A TRANSISTION TO LAKE EFFECT SNOW WILL CONTINUE OVERNIGHT WITH FAVORABLE CONDITION PERSISTING INTO THURSDAY. ANOTHER TRAILING SHRTWV SLIDING SE INTO THE UPPER LAKES WILL MAINTAIN 850-700 MB MOISTURE AND INVERSION HEIGHTS AOA 10K FT. WITH THE WINDS BACKING SLIGHTLY TO 340-330 THE HEAVIER LES WILL CONTINUE TO FOCUS INTO THE FAR WEST AND TO AREAS EAST OF MARQUETTE. 850 MB TEMPS FALLING TO AROUND -20C MAY SHRINK THE DGZ LAYER INTO THE 1K-3K RANGE BUT STILL SHOULD BE SUFFICIENT FOR LSR VALUES CLOSE TO 25/1. ADDITIONAL SNOWFALL AMOUNTS OF 3 TO 7 INCHES ARE POSSIBLE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 441 PM EST WED JAN 30 2013 MODELS ARE IN GOOD GENERAL AGREEMENT THROUGH THE EXTENDED WITH DEEP UPPER TROUGH STARTING THE PERIOD FRI AND GRADUALLY BREAKING DOWN AND SHIFTING WEST THROUGH NEXT WED...AS AN UPPER RIDGE MOVES INTO THE WRN CONUS. GOOD NW WIND LES WILL BE ONGOING INTO THU NIGHT GIVEN NW LOW LEVEL FLOW...AMPLE MOISTURE AND 825MB INVERSION TOP TEMPS AROUND -25C. LATE THU NIGHT AND FRI...A SFC HIGH WILL MOVE S OF THE CWA WHILE A SHORTWAVE TROUGH DIVES IN FROM THE NW FORMING A MESO-LOW OVER ERN LAKE SUPERIOR LATE FRI. THIS TURNS THE NW WINDS WLY BY FRI AFTERNOON...FOCUSING LES OVER THE KEWEENAW AND FAR NE UPPER MI. PRIOR WIND SHIFT...THE BEST LES WILL BE FOCUSED OVER ONTONAGON AND GOGEBIC COUNTIES AND OVER ERN UPPER MI FROM MUNISING TO GRAND MARAIS. LES SHOULD INITIALLY WEAKEN SOME LATE THU NIGHT AS RIDGING MOVES INTO THE AREA...BUT WILL GET A BOOST FROM THE SHORTWAVE LATER ON FRIDAY. THERE IS ALREADY A LES ADVISORY FOR ONTONAGON/GOGEBIC COUNTIES THROUGH THU NIGHT...AND THAT STILL LOOKS FINE. BUT WILL LIKELY ALSO NEED HEADLINES FOR THE ERN U.P. THU NIGHT INTO FRI. THE KEWEENAW MAY ALSO NEED HEADLINES FRI INTO FRI NIGHT. WILL NOT ISSUE ANY NEW HEADLINES AT THIS POINT GIVEN HEADLINES ALREADY IN EFFECT OVER THE ERN U.P. AND SOME UNCERTAINTY AS TO THE RESIDENCE TIME AND INTENSITY OF ANY STRONGER BANDS THAT MOVE ACROSS THE KEWEENAW. THU NIGHT THROUGH FRI NIGHT LOOKS TO BE THE COLDEST PERIOD OF THE NEXT WEEK. LOWS THU NIGHT AND FRI NIGHT LOOKS TO FALL TO THE TEENS BELOW ZERO WITH WIND CHILLS TO -35F OVER PARTS OF THE INTERIOR. HIGHS ON FRI LOOK TO BE AROUND ZERO OVER THE INTERIOR W...AND IN THE LOW TEENS ABOVE ZERO E. WIND CHILL VALUES ARE CURRENTLY FORECAST TO BE IN TEENS BELOW ZERO AT THE WARMEST FRI AFTERNOON OVER THE INTERIOR W...AND IN THE SINGLE DIGITS BELOW ZERO E. WILL LIKELY NEED SOME WIND CHILL ADVISORY HEADLINES UP WHERE THERE ARE NO OTHER WINTER WX HEADLINES. MODELS IN RELATIVELY GOOD AGREEMENT WITH A CLIPPER SHORTWAVE MOVING THROUGH LATE SAT INTO EARLY SAT NIGHT...BUT ONLY MINOR SYNOPTIC SNOW ACCUMULATIONS AND INCREASED NW WIND LES ARE EXPECTED TO RESULT FROM THE SYSTEM. SFC RIDGING MOVES OVER ON SUN AHEAD OF THE NEXT...STRONGER...CLIPPER SYSTEM THAT MODEL DEPICT MOVING THROUGH. ALTHOUGH MODELS SEEM TO AGREE FAIRLY WELL ON THE OVERALL TRACK AND INTENSITY OF THE SYSTEM...THE 00Z/30 ECMWF IS 6-12 HOURS FASTER THAN THE 12Z/30 GFS. SEVERAL INCHES OF SNOW MAY RESULT AREA WIDE FROM THIS SYSTEM. MODELS THEN INDICATE...WITH GREATER UNCERTAINTY...ANOTHER CLIPPER SYSTEM MOVING THROUGH SOMETIME MIDWEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 655 PM EST WED JAN 30 2013 AT KIWD...LAKE EFFECT -SHSN WILL INCREASE TONIGHT AS COLDER AIR FLOWS INTO THE AREA AND LOW-LEVEL WINDS BECOME MORE CYCLONIC. AS A RESULT...MVFR CONDITIONS THIS EVENING SHOULD FALL TO IFR OVERNIGHT THRU MUCH OF THE DAY THU. AT KCMX...LIFR CONDITIONS HAVE ALREADY DEVELOPED AND WILL LIKELY CONTINUE THRU THE FCST PERIOD AS LAKE EFFECT -SHSN CONTINUE UNDER INCREASINGLY COLDER AIR MASS. WITH THE COLDER AIR...SNOWFLAKE SIZE WILL BE SMALL AND VERY EFFECTIVE AT KEEPING VIS LOW. AT KSAW...SYNOPTIC SNOW SHIELD WILL BE EXITING LEAVING LAKE EFFECT -SHSN LATE EVENING THRU THU. AS A RESULT... EXPECT INITIAL LIFR CONDITIONS TO IMPROVE TO IFR THIS EVENING AND TO MOSTLY MVFR OVERNIGHT THRU THU. AS IS TYPICAL FOR LAKE EFFECT SNOW...EXPECT VIS AT ALL SITES TO BE HIGHLY VARIABLE AT TIMES AS SNOW BANDS MOVE ACROSS THE AREA. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 441 PM EST WED JAN 30 2013 N TO NW GALES OF 35 TO 40 KNOTS WILL CONTINUE THROUGH MUCH OF TONIGHT...WITH A FEW GALE FORCE GUSTS TO 35 KNOTS LINGERING E THROUGH THURSDAY. LOW PRESSURE OVER LOWER MICHIGAN WILL LIFT NORTHEAST INTO ONTARIO AND QUEBEC TONIGHT. WITH PLENTY OF COLD AIR SINKING IN BEHIND THE LOW AND STRONG WINDS...HEAVY FREEZING SPRAY WILL PREVAIL THROUGH THURSDAY NIGHT...AND MAY LINGER OVER THE FAR EAST THROUGH FRIDAY NIGHT. A TROUGH WILL LINGER OVER LAKE SUPERIOR THROUGH THURSDAY...AS STRONG HIGH PRESSURE SINKS ACROSS THE PLAINS STATES. EXPECT THE HIGH PRESSURE SYSTEM TO WEAKEN SLIGHTLY OVER THE MISSISSIPPI VALLEY FRIDAY...WHILE PUSHING A RIDGE ACROSS WESTERN LAKE SUPERIOR. WEAK LOW PRESSURE WILL LINGER ACROSS EASTERN LAKE SUPERIOR THROUGH SATURDAY. ANOTHER LOW PRESSURE TROUGH WILL SINK SOUTHWARD FROM MANITOBA INTO THE UPPER GREAT LAKES SATURDAY EVENING...BEFORE MOVING INTO THE LOWER GREAT LAKES DURING THE DAY SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>003-009. WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MIZ005. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR LSZ265>267. GALE WARNING UNTIL 4 AM EST THURSDAY FOR LSZ264>267. HEAVY FREEZING SPRAY WARNING UNTIL 1 AM EST /MIDNIGHT CST/ SATURDAY FOR LSZ162-263-264. LAKE MICHIGAN... NONE. && $$ UPDATE...ROLFSON SHORT TERM...JLB LONG TERM...TITUS AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1007 PM EST WED JAN 30 2013 .UPDATE... THE WIDESPREAD RAIN WHICH HAS BEEN ROLLING ACROSS THE FORECAST AREA THIS EVENING WILL QUICKLY LIFT OFF TO THE NORTHEAST OVER THE NEXT COUPLE OF HOURS. RECENT OBSERVATIONS INDICATE THE BULK OF THESE HEAVIER SHOWERS WILL BE OFF TO THE EAST PRIOR TO THE ARRIVAL OF THE ARCTIC AIR AND CHANGE OVER TO SNOW. NONETHELESS...THE ADVANCE OF DEEPER MOISTURE WITHIN THE MID LEVEL TROUGH AXIS WILL ROTATE THROUGH THE FORECAST AREA OVERNIGHT PROVIDING SOME LIGHT SNOW SHOWERS TO THE AREA. THE RESPONSE OFF LAKE MI FROM THE AGGRESSIVE PUSH OF COLD AIR TONIGHT WILL ALSO BE QUITE GOOD. LAKE ENHANCED SNOW SHOWERS SHOULD SUPPORT SOME HIGHER POPS ACROSS THE SOUTHERN HALF OF THE FORECAST AREA OVERNIGHT. THE HIGHER INTENSITY SNOW SHOWERS SHOULD HOLD OFF UNTIL AFTER DAYBREAK...SO SNOW ACCUMS TONIGHT SHOULD BE MINOR. THE ARCTIC FRONT IS NOW ON THE DOORSTEP OF THE FORECAST AREA AND WILL TRACK EAST OF THE AREA SHORTLY AFTER MIDNIGHT. OVER THE NEXT TWO HOURS...TEMPS WILL RAPIDLY DROP BELOW FREEZING. WHILE THE WINDS WILL HELP DRY THE ROAD SURFACES A BIT...EXPECT THERE WILL SOME SLICK ROADS OVERNIGHT. THE SURFACE LOW NOW OVER LAKE HURON WILL CONTINUE TO DEEPEN AS IT PULLS NORTHEAST OF THE REGION OVERNIGHT. MEANWHILE...STRONG COLD AIR ADVECTION WILL STEEPEN THE LOW LEVEL LAPSE RATES. THE MOST RECENT RAP AND 18Z NAM CONTINUE TO SHOW A SOLID 40-45 KTS IN THE MIXED LAYER OVERNIGHT /ESPECIALLY ACROSS THE EASTERN PORTIONS OF THE FORECAST AREA/. THUS THE CURRENT WIND ADVISORY HEADLINE FOR MUCH OF THE FORECAST AREA WILL REMAIN IN EFFECT. && .AVIATION...ISSUED 628 PM EST WED JAN 30 2013 //DISCUSSION... DEEPENING LOW PRESSURE NOW TRACKING INTO LAKE HURON WILL SEND TWO FRONTS ACROSS SE MI THIS EVENING. THE FIRST FRONT WILL BE TRAVERSING THE TERMINALS AT THE START OF THE TAF PERIOD AND WILL LEAD TO A SLIGHT VEERING OF THE WINDS TO THE SOUTHWEST WITH AN INCREASE IN WIND SPEEDS. THE SECONDARY FRONT...WHICH IS THE TRUE ARCTIC FRONT WILL THEN PUSH THROUGH SE MI AROUND 03Z. THIS FRONT WILL BE MARKED BY A DRAMATIC INCREASE IN WESTERLY WIND SPEEDS...PERSISTING THROUGH THE NIGHT AND INTO THURS MORNING...WITH GUSTS EXPECTED TO TOP 30 KNOTS. WHILE CEILINGS HAVE IMPROVED MARKEDLY THE LAST COUPLE OF HOURS. THE LOWER CEILINGS ACROSS WRN LOWER MI WILL ADVANCE BACK INTO SE MI THIS EVENING WITH THE APPROACH OF THE ARCTIC FRONT. CEILINGS WILL THEN STEADILY IMPROVE DURING THE NIGHT AS THE COLD AIR DEEPENS AND LIFTS INVERSION HEIGHTS. PRECIP PRIOR TO THE ARCTIC FRONT WILL BE ALL RAIN. MINOR SNOW ACCUMS ARE POSSIBLE AS THE RAIN RAPIDLY CHANGES OVER TO SNOW LATE THIS EVENING. FOR DTW...UPSTREAM OBS SUPPORT WIND GUSTS REACHING 25-30 KNOTS BETWEEN 00Z AND 03Z. THE ARCTIC FRONTAL PASSAGE AROUND 03Z WILL VEER THE WINDS TO THE WEST WHILE GUSTS ARE EXPECTED TO REACH 35 KNOTS OR HIGHER. THE STRONG WESTERLY WINDS WILL PERSIST THROUGH THURS MORNING. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILING BELOW 5000 FT TONIGHT AND THURSDAY. * HIGH CONFIDENCE WESTERLY WIND GUSTS WILL EXCEED 30 KNOTS BETWEEN 03Z AND 19Z THURS. * HIGH CONFIDENCE PRECIP TYPE AS RAIN THROUGH 03Z...THEN QUICKLY CHANGING OVER TO SNOW BY 04Z. && .PREV DISCUSSION...ISSUED 345 PM EST WED JAN 30 2013 SHORT TERM... TONIGHT THERE ARE SEVERAL CONCERNS ASSOCIATED WITH THE FORECAST TONIGHT FOR CONDITIONS THAT WILL HAVE AT LEAST MODERATE IMPACT AROUND SE MICHIGAN. THE ADVISORY FOR HIGH WIND WILL BE MOST SIGNIFICANT FOLLOWED CLOSELY BY THE COMBINATION OF FALLING TEMPERATURES AND RAIN CHANGING TO SNOW ADDING A LAYER OF COMPLEXITY. ALL OF THIS WILL BE DRIVEN BY A WAVE OF LOW PRESSURE THAT WILL MOVE FROM SOUTHWEST LOWER MICHIGAN DURING THE AFTERNOON, THROUGH CENTRAL LAKE HURON AND INTO EASTERN ONTARIO TONIGHT, ALL THE WHILE DEEPENING AS IT GOES. THE DEEPENING TREND OF THE LOW AS IT PASSES TO OUR EAST WILL BE FOSTERED BY THE DYNAMICS OF THE NEGATIVE TILT SHORT WAVE THAT IS ALREADY TAKING SHAPE IN SATELLITE IMAGERY DURING THE AFTERNOON. INCREASING SURFACE WIND TRAILING THE LOW IS ALSO OBSERVED TO PRODUCE WIND GUSTS AROUND 30 KNOTS OVER THE MIDWEST AT PRESS TIME. WITH THE SYSTEM ALREADY OFF TO A GOOD START, CONFIDENCE IS INCREASED IN THE DEPICTIONS SHOWN IN THE ARRAY OF 12Z MODEL OUTPUT THAT BUILD A STRONG WESTERLY WIND FIELD OVER SE MICHIGAN BY MIDNIGHT. SOME GUSTINESS IS EXPECTED IN THE WARMER AIR AHEAD OF THE FRONT, ASSOCIATED WITH THE LOW LEVEL JET, AND WITH THE ISALLOBARIC COMPONENT OF FORCING IMMEDIATELY BEHIND THE FRONT, BUT THESE ELEMENTS ARE NOT EXPECTED TO EXCEED ADVISORY CRITERIA. THAT IS INSTEAD LIKELY TO OCCUR TOWARD MIDNIGHT THROUGH WEDNESDAY MORNING AS DYNAMICALLY DRIVEN MID LEVEL SUBSIDENCE AND STRONG COLD ADVECTION HELP DIRECT A 45-50 KNOT WIND FIELD TOWARD THE SURFACE FROM THE 850 TO 700 MB LAYER. MODEL CROSS SECTIONS INDICATE NEARLY 10 DEGREES(K) OF THETA SURFACES INTERSECTING THE GROUND DURING THE INTERVAL OF ISENTROPIC DECENT. MODEL SOUNDINGS THEN SHOW THE MIXED LAYER DEEPENING TO NEAR THE 800 MB LEVEL FOR THE LATE OVERNIGHT HOURS WITH 45 KNOTS OF WIND AVAILABLE FOR CONTRIBUTION TO SURFACE WIND GUSTS. AREAL COVERAGE WILL BE GREATEST ALONG AND SOUTH OF INTERSTATE 69 WITH THE THUMB VULNERABLE DUE TO WIND GUSTS MOVING OFF OF SAGINAW BAY. PLAN TO LEAVE THE TRI CITIES OUT OF THE HEADLINE FOR NOW. THE STRONG WINDS WILL PULL DRAMATICALLY COLDER AIR INTO SE MICHIGAN DURING THE NIGHT WITH READINGS DROPPING INTO THE UPPER TEENS IN THE TRI CITIES BY SUNRISE TO THE MID 20S METRO DETROIT. THE BULK OF PRECIPITATION WILL COME IN THE FORM OF RAIN SHOWERS THROUGH MID EVENING WITH THE CHANGE TO SNOW AT THE VERY TAIL END FOR JUST A DUSTING OF ACCUMULATION IN THE DETROIT AREA AND UP TO AN INCH IN THE NORTHERN THUMB. LONG TERM... LAKE MICHIGAN LAKE EFFECT MACHINE WILL BE CRANKING UP THURSDAY...ENHANCED BY A GOOD UPPER LEVEL WAVE/MID LEVEL COLD POOL SWINGING THROUGH THE MIDWEST/WESTERN OHIO VALLEY TOMORROW AFTERNOON. STRONG WESTERLY WINDS (35-45 MPH) IN WAKE OF THE QUICKLY DEEPENING LOW PRESSURE WILL USHER IN SUFFICIENTLY COLD AIRMASS...UPPER NEGATIVE TEENS AT 850 MB OVER LOWER MICHIGAN...BUT LOWER NEGATIVE 20S SWINGING THROUGH THE WESTERN OHIO VALLEY. 700 MB COLD POOL OF -28 TO -30 C OVER SOUTHERN LOWER MICHIGAN THURSDAY EVENING WITH MODEST 925-850 MB LIFT/CONVERGENCE EXTENDING INTO SOUTHEAST MICHIGAN...AND PLANNING ON CARRYING NUMEROUS POPS..ALTHOUGH FOCUS OF ACTIVITY WILL LIKELY SHIFT FROM NORTH TO SOUTH THROUGH THE NIGHT AS MODEST 850 THETA-E RIDGE SETTLES SOUTH. WITH A HIGH FLUFF FACTOR TO SNOW...20+:1 RATIOS...A QUICK INCH OR TWO IS LIKELY IN SPOTS AS 925-850 MB PROFILES REMAIN IN THE DENDRITIC ZONE GROWTH REGION. HEART OF THE COLD AIR/THERMAL TROUGH AXIS WILL BE IN PLACE FOR FRIDAY...WITH 850 MB TEMPS HOVERING AROUND -20 C ON FRIDAY...AND HAVE NO COMPLAINTS WITH INHERITED MAXES IN THE UPPER TEENS TO AROUND 20...IN LINE WITH LATEST GUIDANCE. A SURFACE RIDGE WILL ATTEMPT TO MOVE IN FRIDAY NIGHT. IF THIS IS SUFFICIENT IN CLEARING OUT THE LOW CLOUDS...LOOKING AT MINS AT OR BELOW ZERO FOR MUCH OF THE AREA WITH EXPECTED FRESH SNOW COVER. CONFIDENCE IS NOT HIGH...AND WILL HAVE TO PLAY IT CONSERVATIVE (LOW/MID SINGLE NUMBERS) AS THERE IS ALSO LURKING WARM ADVECTION CLOUDS STREAMING INTO THE WESTERN GREAT LAKES. POLAR VORTEX LOOKS TO BE ANCHORED OVER/NEAR FAR NORTHERN HUDSON BAY/SOUTHAMPTON ISLAND OVER THE NEXT SEVERAL DAYS...AND THIS WILL MAINTAIN THE UPPER LEVEL NORTHWEST FLOW WITH A COUPLE SHORTWAVES/CLIPPER SYSTEMS TO IMPACT OR TRACK NEAR SOUTHERN LOWER MICHIGAN. WITH MOISTURE AT A PREMIUM...USUALLY NEED TO BE ON THE NORTHEAST FLANK OF THE LOW (WARM ADVECTION/ISENTROPIC ASCENT/MOISTURE CONVERGENCE) TO GET ANY SUBSTANTIAL SNOWFALL. BEST GUESS AT TIMING OF SYSTEMS WOULD BE SATURDAY NIGHT AND THEN AGAIN ON MONDAY. 12Z TRENDS OF EURO/GFS SUGGEST SATURDAY NIGHTS SYSTEM WILL TRACK JUST A BIT TOO FAR SOUTH...WITH MONDAYS SYSTEM/TRACK MORE FAVORABLE. THE EARLY NEXT WEEK LOW WILL ALSO HAVE A BIT MORE OF A PACIFIC ORIGIN...AND THUS A BIT MORE MOISTURE. STILL TOO EARLY TO GET A GOOD HANDLE OF THE GULF OF ALASKA ENERGY AND EVENTUAL BREAKDOWN/SPILLING OVER INTO THE CONUS HOWEVER. MARINE... A POWERFUL COLD FRONT WILL SWEEP THROUGH LAKE HURON AND LOWER MICHIGAN TONIGHT. INCREASING NORTHWEST WINDS AND A SURGE OF COLDER AIR WILL BRING GALES TO ALL MARINE AREAS. CONSIDERABLE INSTABILITY ACROSS THE LONG FETCH IN NORTHWEST FLOW OF THE OPEN WATERS WILL MAINTAIN A LONGER PERIOD OF GALES FOR CENTRAL PORTIONS OF THE LAKE THROUGH THURSDAY. THE COMBINATION OF THE STRONG WINDS, ARCTIC AIR, AND COLDER WATER TEMPERATURE WILL LEAD TO HEAVY FREEZING SPRAY ACROSS NORTHERN SECTIONS OF LAKE HURON DURING THIS TIME. HIGH PRESSURE WILL SETTLE OVER THE OHIO VALLEY AND BRING IMPROVED CONDITIONS BY FRIDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WIND ADVISORY...MIZ049-MIZ054-MIZ055-MIZ061-MIZ062-MIZ063-MIZ068- MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-MIZ083...UNTIL NOON THURSDAY. LAKE HURON... GALE WARNING...LHZ361...UNTIL NOON THURSDAY. HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362...UNTIL 7 PM THURSDAY. GALE WARNING...LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...UNTIL 7 PM THURSDAY. GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...UNTIL 4 PM THURSDAY. LAKE ST CLAIR... GALE WARNING...UNTIL 4 PM THURSDAY. MI WATERS OF LAKE ERIE... GALE WARNING...UNTIL 4 PM THURSDAY. && $$ UPDATE.......SC AVIATION.....SC SHORT TERM...BT LONG TERM....SF MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1126 PM CST WED JAN 30 2013 .AVIATION...06Z KGRI TAF...AN APPROACHING UPPER LEVEL DISTURBANCE WILL SPREAD MVFR CIGS ACROSS THE TERMINAL BY THE EARLY MORNING HOURS THURSDAY...WITH A FEW SNOW FLAKES NOT OUT OF THE QUESTION. ALREADY SEEING MVFR CIGS TO THE NORTHWEST AT KVTN WITH SOME -SN...AND EXPECT THIS CLOUD COVER TO REACH KGRI AROUND 31/12Z...AND PERSIST THROUGH AROUND 31/18Z. WINDS WILL THE PRIMARY FOCUS THROUGH THE DAY THURSDAY AS AN AREA OF SURFACE HIGH PRESSURE OVER THE DAKOTAS SLIDES SOUTHWARD...RESULTING IN A TIGHTENING PRESSURE GRADIENT. EXPECT WINDS TO GUST AS HIGH AS 30KTS DURING THE AFTERNOON HOURS...BEFORE RAPIDLY DIMINISHING AROUND 01/00Z...AS THE CENTER OF THIS HIGH PRESSURE SYSTEM REACHES EASTERN NEBRASKA. && .PREV DISCUSSION... /ISSUED 956 PM CST WED JAN 30 2013/ UPDATE...EVENING UPPER AIR ANALYSIS PER RAP ANALYSIS DATA SUGGESTS A LARGE MID AND UPPER LEVEL LONGWAVE TROUGH PERSISTS OVER THE CENTRAL CONUS. MID AND UPPER LEVEL JET ENERGY EXTENDS SOUTH/SOUTHEAST ACROSS THE WESTERN CONUS...THEN EAST ACROSS THE SOUTHERN PLAINS...AND EVENTUALLY NORTHEAST ACROSS THE EASTERN ONE- THIRD OF THE CONUS. ALTHOUGH MID AND UPPER TROPOSPHERIC FLOW HAS BEEN FAIRLY WEAK OVER OUR AREA THROUGH THIS EVENING...THE MID LEVEL WIND FIELD IS INTENSIFYING WITH THE APPROACH OF A ~80KT MID LEVEL JET STREAK FROM THE NORTHWEST. WATER VAPOR IMAGERY INDICATES FAIRLY MEAGER MID LEVEL MOISTURE OVER OUR AREA...ALTHOUGH SOME MODEST INCREASE IN MID LEVEL MOISTURE IS NOTED ADVECTING INTO THE AREA FROM THE NORTHWEST VIA THE MID LEVEL JET AXIS. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER PORTIONS OF SOUTHERN MANITOBA AND SOUTHERN ONTARIO...MOVING SOUTH/SOUTHEAST WITHIN THE MEAN FLOW. AT THE SURFACE LOW BAROMETRIC PRESSURE IS NOTED OVER PORTIONS OF CENTRAL NEBRASKA...WITH RAPIDLY INCREASING BAROMETRIC PRESSURE NOTED UPSTREAM ACROSS THE DAKOTAS AND PORTIONS OF MONTANA. THE LOW LEVEL WIND FIELD OVER OUR AREA REMAINS FAIRLY LIGHT BUT STILL FROM THE NORTHWEST FOR THE MOST PART. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN ALL SUGGEST THE MID LEVEL SHORT WAVE...CURRENTLY ADVANCING SOUTH/SOUTHEAST FROM SOUTHERN CANADA...WILL CONTINUE MOVING SOUTHEAST ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY THROUGH THE NEXT 18-24 HOURS. IT APPEARS AS THOUGH THE PRIMARY AXIS OF OMEGA AHEAD OF THE MID LEVEL TROUGH AXIS WILL REMAIN NORTHEAST OF OUR AREA...ALTHOUGH THE SOUTHWESTERN PERIPHERY OF THE MID LEVEL TROUGH AXIS COULD EXTEND JUST FAR ENOUGH SOUTHWEST TO CLIP NORTHEASTERN PORTIONS OF OUR CWA AND GENERATE SOME VERY LIGHT PRECIPITATION TONIGHT. FORECAST PROXIMITY SOUNDINGS FROM ACROSS OUR CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST LOW TO MID TROPOSPHERIC MOISTURE WILL LIKELY REMAIN TOO MEAGER FOR SIGNIFICANT PRECIPITATION PRODUCTION...BUT STILL CANNOT RULE OUT A FEW SNOW FLURRIES ACROSS OUR NORTHEAST. OVERALL THE GOING FORECAST IS IN GREAT SHAPE...BUT DID GO AHEAD AND TRIM THE MENTION OF FLURRIES ACROSS OUR CWA...AND THIS MENTION IS NOW RELEGATED TO OUR FAR NORTHEASTERN CWA. FORECAST OVERNIGHT LOWS ALSO LOOK GOOD FOR THE TIME BEING...GENERALLY IN THE TEENS WITH THURSDAY MORNING APPARENT TEMPERATURE VALUES APPROACHING -10 ACROSS OUR NORTHEAST AROUND SUNRISE. ALL OTHER CHANGES WERE TO HOURLY TEMPERATURE...WIND...SKY...AND DEWPOINT GRIDS TO BETTER REFLECT CURRENT CONDITIONS. PREV DISCUSSION... /ISSUED 423 PM CST WED JAN 30 2013/ SHORT TERM...TONIGHT AND THURSDAY. WE WILL BE WITHIN NORTHWEST FLOW...BETWEEN THE MEAN TROUGH IN THE EAST AND RIDGE ON THE WEST COAST. ANOTHER SHORTWAVE TROUGH SWINGS TROUGH LATE TONIGHT/EARLY THURSDAY MORNING TO GIVE US A SHOT AT SOME FLURRIES...ESPECIALLY NORTH. SREF INDICATING SOME SPOTTY LOW CHANCES OF ACCUMULATING PRECIPITATION...BUT LEANING TOWARDS FLURRIES WITH THE DRY LOWER LEVELS. SOME VORTICITY HOLDS ON LONGER IN THE SOUTH...SO KEPT SOME SLIGHT CHANCES OF FLURRIES THERE THROUGH THE ENTIRE MORNING. STRONG COLD AIR ADVECTION IS ADVERTISED AS SURFACE HIGH PRESSURE BUILDS IN TOMORROW. WITH ANTICIPATED CONSIDERABLE SKY COVER FOR MOST OF THE DAY AND 18Z 850 MB TEMPS NEAR -20C NEAR ORD TO -10C IN THE SOUTHERN CWA...TEMPERATURES WILL NOT GO VERY FAR...SO HAVE LOWERED TEMPERATURES CONSIDERABLY FOR THURSDAY...ESPECIALLY NORTH. THE WIND WILL BECOME BRISK AGAIN FOR THURSDAY WITH THE STRONG COLD AIR ADVECTION....WITH PLACES NEAR 0RD APPROACHING -15F IN THE EARLY MORNING THURSDAY. SNOW PACK MAY HAVE SOME AFFECT ON TEMPERATURES...BUT MOST OF THE CHILL WILL BE FROM THE COLD AIR ADVECTION ANTICIPATED. LONG TERM...THURSDAY EVENING THROUGH NEXT WEDNESDAY. THE SHORT STORY THROUGH THIS 6-DAY PERIOD IS THAT THE FORECAST REMAINS PRECIPITATION FREE...ALTHOUGH WILL HAVE TO WATCH FOR THE POTENTIAL FOR SOME PESKY FLURRIES OR VERY LIGHT SNOW DEVELOPMENT FRIDAY/FRIDAY NIGHT MAINLY NORTHEAST. OTHERWISE...TEMPERATURES WILL BE A CONSIDERABLE CHALLENGE ESPECIALLY FRIDAY-SATURDAY AS WARMER AIR MOVING IN FROM THE WEST STARTS A FIERCE BATTLE WITH THE RESPECTABLE 1-5 INCH SNOW PACK NOW BLANKETING THE SOUTHEAST 1/2 OF OUR CWA. OVERALL THOUGH...LEGITIMATELY ABOVE NORMAL TEMPERATURES IN THE 40S/50S LOOK TO DOMINATE THE EARLY-MIDDLE PART OF NEXT WEEK. STARTING OFF THURSDAY NIGHT...MODELS SUCH AS THE 12Z NAM/GFS/ECMWF ARE IN GOOD AGREEMENT THAT THE VERY BEGINNING STAGES OF MODEST WARM AIR ADVECTION WILL START GETTING UNDERWAY IN THE LOW LEVELS...AS THE COLD MID/UPPER TROUGH EDGES FARTHER EAST AWAY FROM THE CENTRAL PLAINS. AT THE SURFACE...THE CWA WILL BE NEAR OR JUST WEST OF A FAIRLY STRONG SURFACE RIDGE AXIS CENTERED OVER THE MO VALLEY THROUGH THE FIRST PART OF THE NIGHT...WHILE SOUTHERLY BREEZES OF AROUND 10 MPH WILL KICK INTO GEAR LATER IN THE NIGHT IN THE RETURN FLOW AROUND THE DEPARTING HIGH. AS A RESULT...DEPENDING ON CLOUD COVER TEMPS COULD REALLY DIP IN THE EVENING BEFORE EXHIBITING A SLIGHT LATE-NIGHT RISE. CLOUD TRENDS WILL BE A BIT TRICKY...AS MODELS SHOW THE POTENTIAL FOR A TRANSIENT BAND OF MID LEVEL SATURATION WORKING ACROSS THE CWA FROM WEST-EAST THROUGH THE NIGHT. ALTHOUGH ITS NOT OUT OF THE QUESTION A FEW FLURRIES COULD TRY FORMING FROM THIS...CHANCES LOOK LOW ENOUGH TO LEAVE OUT AT THIS TIME. AS FOR ACTUAL LOW TEMPS...LOWERED EAST-NORTHEAST ZONES A BIT FROM PREVIOUS FORECAST. NOW HAVE LOWS DOWN IN THE SINGLE DIGITS ABOVE ZERO MOST AREAS...EXCEPT FOR A 10-15 RANGE FAR SOUTHWEST WHERE THE SOUTH WINDS KICK IN A BIT SOONER. FRIDAY/FRIDAY NIGHT...AS ALREADY MENTIONED WILL NEED TO MONITOR FOR SOME LOW-IMPACT FLURRY/VERY LIGHT SNOW ACTIVITY ESPECIALLY IN NORTHEAST COUNTIES AS A LOW AMPLITUDE SHORTWAVE TROUGHS DROPS OVERHEAD IN WEST-NORTHWEST FLOW ALOFT...BUT WITH THIS STILL BEING 4-5 PERIODS OUT AM CONTENT LEAVING IT OUT FOR NOW...AND LET LATER SHIFTS TAKE A CLOSER LOOK. NO MATTER WHAT...THE MUCH BETTER FOCUS FOR POTENTIALLY MEASURABLE SNOW WILL FOCUS WELL EAST INTO IA. HIGH TEMPS FRIDAY ARE REALLY GOING TO BE A CHALLENGE...ESPECIALLY ALONG THE INTERFACE BETWEEN THE NEARLY SNOW-FREE GROUND AND THE DEEPER SNOWPACK. BREEZY SOUTHWEST WINDS SHOULD HAVE NO PROBLEM BOOSTING ROUGHLY THE WESTERN HALF OF THE CWA WELL INTO THE 40S...WHILE EASTERN AREAS COULD STAY WELL DOWN IN THE LOW-MID 30S. CONFIDENCE IN THE MAGNITUDE OF THIS GRADIENT IS FAIRLY LOW AT THIS TIME. LOWS FRIDAY NIGHT ARE FORECAST QUITE A BIT WARMER THAN THURS NIGHT THANKS TO DEVELOPING WESTERLY FLOW BEHIND A PASSING TROUGH AXIS...AND HAVE ALL AREAS HOLDING UP IN THE LOW-MID 20S. SATURDAY/SATURDAY NIGHT...CONTINUED WEST-NORTHWEST DOWNSLOPE LOW LEVEL FLOW SHOULD AID THE CONTINUED WARM-UP...AND MADE LITTLE CHANGE TO HIGHS WITH MOST OF THE CWA REACHING THE MID-UPPER 40S...EXCEPT FOR LOW 40S IN THE FAR SOUTHEAST ESPECIALLY AROUND HEBRON WHERE THE DEEPER SNOW EXISTS. SUNDAY/SUNDAY NIGHT...CONFIDENCE REMAINS FAIRLY HIGH IN DRY CONDITIONS...DESPITE THE PASSAGE OF ANOTHER QUICK MOVING SHORTWAVE TROUGH IN THE PERSISTENT WEST/NORTHWEST FLOW ALOFT. THE ONLY REAL IMPACT FROM THIS WAVE AT THE SURFACE WILL BE THE PASSAGE OF ANOTHER MODEST SURFACE TROUGH MAINLY SUNDAY NIGHT. FOR HIGHS...ANTICIPATE THAT THE SNOWPACK-EFFECTS SHOULD BE TEMPERED A BIT VERSUS FRIDAY/SATURDAY...SO HAVE A BIT MORE UNIFORM TEMPERATURE FIELD...WITH UPPER 40S/LOW 50S MOST AREAS EXCEPT MID 40S IN THE SOUTHEAST. MONDAY/MONDAY NIGHT...CONTINUED NORTHWESTERLY FLOW ALOFT AS A BROAD RIDGE STARTS BUILDING EASTWARD OVER THE WESTERN CONUS A BIT. THE PREFERRED ECWMF SOLUTION KEEPS ANY PRECIP-PRODUCING SHORTWAVE ENERGY WELL EAST OF THE LOCAL AREA ALONG AN AXIS FROM THE DAKOTAS THROUGH IA. WITH LITTLE CHANGE IN THE LOW LEVEL TEMP FIELDS...HAVE HIGHS SIMILAR TO SUNDAY WITH MOST AREAS UPPER 40S TO LOW 50S. TUESDAY/TUESDAY NIGHT...CONTINUED DRY AS A BRIEF PERIOD OF MID/UPPER RIDGING TRANSLATES OVERHEAD...AND AGAIN VERY SIMILAR HIGH TEMPERATURES AS PREVIOUS FEW DAYS WITH UPPER 40S MOST NEB ZONES AND LOW-MID 50S KS. WEDNESDAY...STILL NO LEGITIMATE SIGN OF PRECIP...AS MODELS ADVERTISE FAIRLY UNEVENTFUL QUASI-ZONAL FLOW AT THIS TIME. ONCE AGAIN...HIGHS RANGING UPPER 40S NORTHEAST TO MID-50S SOUTHWEST. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
956 PM CST WED JAN 30 2013 .UPDATE...EVENING UPPER AIR ANALYSIS PER RAP ANALYSIS DATA SUGGESTS A LARGE MID AND UPPER LEVEL LONGWAVE TROUGH PERSISTS OVER THE CENTRAL CONUS. MID AND UPPER LEVEL JET ENERGY EXTENDS SOUTH/SOUTHEAST ACROSS THE WESTERN CONUS...THEN EAST ACROSS THE SOUTHERN PLAINS...AND EVENTUALLY NORTHEAST ACROSS THE EASTERN ONE- THIRD OF THE CONUS. ALTHOUGH MID AND UPPER TROPOSPHERIC FLOW HAS BEEN FAIRLY WEAK OVER OUR AREA THROUGH THIS EVENING...THE MID LEVEL WIND FIELD IS INTENSIFYING WITH THE APPROACH OF A ~80KT MID LEVEL JET STREAK FROM THE NORTHWEST. WATER VAPOR IMAGERY INDICATES FAIRLY MEAGER MID LEVEL MOISTURE OVER OUR AREA...ALTHOUGH SOME MODEST INCREASE IN MID LEVEL MOISTURE IS NOTED ADVECTING INTO THE AREA FROM THE NORTHWEST VIA THE MID LEVEL JET AXIS. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER PORTIONS OF SOUTHERN MANITOBA AND SOUTHERN ONTARIO...MOVING SOUTH/SOUTHEAST WITHIN THE MEAN FLOW. AT THE SURFACE LOW BAROMETRIC PRESSURE IS NOTED OVER PORTIONS OF CENTRAL NEBRASKA...WITH RAPIDLY INCREASING BAROMETRIC PRESSURE NOTED UPSTREAM ACROSS THE DAKOTAS AND PORTIONS OF MONTANA. THE LOW LEVEL WIND FIELD OVER OUR AREA REMAINS FAIRLY LIGHT BUT STILL FROM THE NORTHWEST FOR THE MOST PART. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN ALL SUGGEST THE MID LEVEL SHORT WAVE...CURRENTLY ADVANCING SOUTH/SOUTHEAST FROM SOUTHERN CANADA...WILL CONTINUE MOVING SOUTHEAST ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY THROUGH THE NEXT 18-24 HOURS. IT APPEARS AS THOUGH THE PRIMARY AXIS OF OMEGA AHEAD OF THE MID LEVEL TROUGH AXIS WILL REMAIN NORTHEAST OF OUR AREA...ALTHOUGH THE SOUTHWESTERN PERIPHERY OF THE MID LEVEL TROUGH AXIS COULD EXTEND JUST FAR ENOUGH SOUTHWEST TO CLIP NORTHEASTERN PORTIONS OF OUR CWA AND GENERATE SOME VERY LIGHT PRECIPITATION TONIGHT. FORECAST PROXIMITY SOUNDINGS FROM ACROSS OUR CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST LOW TO MID TROPOSPHERIC MOISTURE WILL LIKELY REMAIN TOO MEAGER FOR SIGNIFICANT PRECIPITATION PRODUCTION...BUT STILL CANNOT RULE OUT A FEW SNOW FLURRIES ACROSS OUR NORTHEAST. OVERALL THE GOING FORECAST IS IN GREAT SHAPE...BUT DID GO AHEAD AND TRIM THE MENTION OF FLURRIES ACROSS OUR CWA...AND THIS MENTION IS NOW RELEGATED TO OUR FAR NORTHEASTERN CWA. FORECAST OVERNIGHT LOWS ALSO LOOK GOOD FOR THE TIME BEING...GENERALLY IN THE TEENS WITH THURSDAY MORNING APPARENT TEMPERATURE VALUES APPROACHING -10 ACROSS OUR NORTHEAST AROUND SUNRISE. ALL OTHER CHANGES WERE TO HOURLY TEMPERATURE...WIND...SKY...AND DEWPOINT GRIDS TO BETTER REFLECT CURRENT CONDITIONS. && .PREV DISCUSSION... /ISSUED 522 PM CST WED JAN 30 2013/ AVIATION...00Z KGRI TAF. VFR CONDITIONS ARE FORECAST THROUGH THE NEXT 24 HOURS. SCATTERED TO BROKEN CLOUDS NEAR 3500FT AGL ARE EXPECTED AS A MID LEVEL SHORT WAVE CLIPS THE AREA TO THE NORTHEAST. ONE SET OF GUIDANCE DOES SUGGEST A PERIOD OF MVFR CEILINGS COULD BE REALIZED AT THE TERMINAL TONIGHT...BUT CONFIDENCE IN MVFR CONDITIONS ACTUALLY BEING REALIZED AT KGRI IS TOO LOW TO PRESENT IN THE TAF AT THIS TIME. THE SURFACE WIND WILL REMAIN FROM THE NORTHWEST AND INTENSIFY DURING THE TAF PERIOD...SUSTAINED NEAR 19KTS AND GUSTING NEAR 28KTS DURING THE DAY THURSDAY. VISIBILITY RESTRICTION WILL NOT BE OBSERVED AT THE TERMINAL THROUGH THE NEXT 24 HOURS. PREV DISCUSSION... /ISSUED 423 PM CST WED JAN 30 2013/ SHORT TERM...TONIGHT AND THURSDAY. WE WILL BE WITHIN NORTHWEST FLOW...BETWEEN THE MEAN TROUGH IN THE EAST AND RIDGE ON THE WEST COAST. ANOTHER SHORTWAVE TROUGH SWINGS TROUGH LATE TONIGHT/EARLY THURSDAY MORNING TO GIVE US A SHOT AT SOME FLURRIES...ESPECIALLY NORTH. SREF INDICATING SOME SPOTTY LOW CHANCES OF ACCUMULATING PRECIPITATION...BUT LEANING TOWARDS FLURRIES WITH THE DRY LOWER LEVELS. SOME VORTICITY HOLDS ON LONGER IN THE SOUTH...SO KEPT SOME SLIGHT CHANCES OF FLURRIES THERE THROUGH THE ENTIRE MORNING. STRONG COLD AIR ADVECTION IS ADVERTISED AS SURFACE HIGH PRESSURE BUILDS IN TOMORROW. WITH ANTICIPATED CONSIDERABLE SKY COVER FOR MOST OF THE DAY AND 18Z 850 MB TEMPS NEAR -20C NEAR ORD TO -10C IN THE SOUTHERN CWA...TEMPERATURES WILL NOT GO VERY FAR...SO HAVE LOWERED TEMPERATURES CONSIDERABLY FOR THURSDAY...ESPECIALLY NORTH. THE WIND WILL BECOME BRISK AGAIN FOR THURSDAY WITH THE STRONG COLD AIR ADVECTION....WITH PLACES NEAR 0RD APPROACHING -15F IN THE EARLY MORNING THURSDAY. SNOW PACK MAY HAVE SOME AFFECT ON TEMPERATURES...BUT MOST OF THE CHILL WILL BE FROM THE COLD AIR ADVECTION ANTICIPATED. LONG TERM...THURSDAY EVENING THROUGH NEXT WEDNESDAY. THE SHORT STORY THROUGH THIS 6-DAY PERIOD IS THAT THE FORECAST REMAINS PRECIPITATION FREE...ALTHOUGH WILL HAVE TO WATCH FOR THE POTENTIAL FOR SOME PESKY FLURRIES OR VERY LIGHT SNOW DEVELOPMENT FRIDAY/FRIDAY NIGHT MAINLY NORTHEAST. OTHERWISE...TEMPERATURES WILL BE A CONSIDERABLE CHALLENGE ESPECIALLY FRIDAY-SATURDAY AS WARMER AIR MOVING IN FROM THE WEST STARTS A FIERCE BATTLE WITH THE RESPECTABLE 1-5 INCH SNOW PACK NOW BLANKETING THE SOUTHEAST 1/2 OF OUR CWA. OVERALL THOUGH...LEGITIMATELY ABOVE NORMAL TEMPERATURES IN THE 40S/50S LOOK TO DOMINATE THE EARLY-MIDDLE PART OF NEXT WEEK. STARTING OFF THURSDAY NIGHT...MODELS SUCH AS THE 12Z NAM/GFS/ECMWF ARE IN GOOD AGREEMENT THAT THE VERY BEGINNING STAGES OF MODEST WARM AIR ADVECTION WILL START GETTING UNDERWAY IN THE LOW LEVELS...AS THE COLD MID/UPPER TROUGH EDGES FARTHER EAST AWAY FROM THE CENTRAL PLAINS. AT THE SURFACE...THE CWA WILL BE NEAR OR JUST WEST OF A FAIRLY STRONG SURFACE RIDGE AXIS CENTERED OVER THE MO VALLEY THROUGH THE FIRST PART OF THE NIGHT...WHILE SOUTHERLY BREEZES OF AROUND 10 MPH WILL KICK INTO GEAR LATER IN THE NIGHT IN THE RETURN FLOW AROUND THE DEPARTING HIGH. AS A RESULT...DEPENDING ON CLOUD COVER TEMPS COULD REALLY DIP IN THE EVENING BEFORE EXHIBITING A SLIGHT LATE-NIGHT RISE. CLOUD TRENDS WILL BE A BIT TRICKY...AS MODELS SHOW THE POTENTIAL FOR A TRANSIENT BAND OF MID LEVEL SATURATION WORKING ACROSS THE CWA FROM WEST-EAST THROUGH THE NIGHT. ALTHOUGH ITS NOT OUT OF THE QUESTION A FEW FLURRIES COULD TRY FORMING FROM THIS...CHANCES LOOK LOW ENOUGH TO LEAVE OUT AT THIS TIME. AS FOR ACTUAL LOW TEMPS...LOWERED EAST-NORTHEAST ZONES A BIT FROM PREVIOUS FORECAST. NOW HAVE LOWS DOWN IN THE SINGLE DIGITS ABOVE ZERO MOST AREAS...EXCEPT FOR A 10-15 RANGE FAR SOUTHWEST WHERE THE SOUTH WINDS KICK IN A BIT SOONER. FRIDAY/FRIDAY NIGHT...AS ALREADY MENTIONED WILL NEED TO MONITOR FOR SOME LOW-IMPACT FLURRY/VERY LIGHT SNOW ACTIVITY ESPECIALLY IN NORTHEAST COUNTIES AS A LOW AMPLITUDE SHORTWAVE TROUGHS DROPS OVERHEAD IN WEST-NORTHWEST FLOW ALOFT...BUT WITH THIS STILL BEING 4-5 PERIODS OUT AM CONTENT LEAVING IT OUT FOR NOW...AND LET LATER SHIFTS TAKE A CLOSER LOOK. NO MATTER WHAT...THE MUCH BETTER FOCUS FOR POTENTIALLY MEASURABLE SNOW WILL FOCUS WELL EAST INTO IA. HIGH TEMPS FRIDAY ARE REALLY GOING TO BE A CHALLENGE...ESPECIALLY ALONG THE INTERFACE BETWEEN THE NEARLY SNOW-FREE GROUND AND THE DEEPER SNOWPACK. BREEZY SOUTHWEST WINDS SHOULD HAVE NO PROBLEM BOOSTING ROUGHLY THE WESTERN HALF OF THE CWA WELL INTO THE 40S...WHILE EASTERN AREAS COULD STAY WELL DOWN IN THE LOW-MID 30S. CONFIDENCE IN THE MAGNITUDE OF THIS GRADIENT IS FAIRLY LOW AT THIS TIME. LOWS FRIDAY NIGHT ARE FORECAST QUITE A BIT WARMER THAN THURS NIGHT THANKS TO DEVELOPING WESTERLY FLOW BEHIND A PASSING TROUGH AXIS...AND HAVE ALL AREAS HOLDING UP IN THE LOW-MID 20S. SATURDAY/SATURDAY NIGHT...CONTINUED WEST-NORTHWEST DOWNSLOPE LOW LEVEL FLOW SHOULD AID THE CONTINUED WARM-UP...AND MADE LITTLE CHANGE TO HIGHS WITH MOST OF THE CWA REACHING THE MID-UPPER 40S...EXCEPT FOR LOW 40S IN THE FAR SOUTHEAST ESPECIALLY AROUND HEBRON WHERE THE DEEPER SNOW EXISTS. SUNDAY/SUNDAY NIGHT...CONFIDENCE REMAINS FAIRLY HIGH IN DRY CONDITIONS...DESPITE THE PASSAGE OF ANOTHER QUICK MOVING SHORTWAVE TROUGH IN THE PERSISTENT WEST/NORTHWEST FLOW ALOFT. THE ONLY REAL IMPACT FROM THIS WAVE AT THE SURFACE WILL BE THE PASSAGE OF ANOTHER MODEST SURFACE TROUGH MAINLY SUNDAY NIGHT. FOR HIGHS...ANTICIPATE THAT THE SNOWPACK-EFFECTS SHOULD BE TEMPERED A BIT VERSUS FRIDAY/SATURDAY...SO HAVE A BIT MORE UNIFORM TEMPERATURE FIELD...WITH UPPER 40S/LOW 50S MOST AREAS EXCEPT MID 40S IN THE SOUTHEAST. MONDAY/MONDAY NIGHT...CONTINUED NORTHWESTERLY FLOW ALOFT AS A BROAD RIDGE STARTS BUILDING EASTWARD OVER THE WESTERN CONUS A BIT. THE PREFERRED ECWMF SOLUTION KEEPS ANY PRECIP-PRODUCING SHORTWAVE ENERGY WELL EAST OF THE LOCAL AREA ALONG AN AXIS FROM THE DAKOTAS THROUGH IA. WITH LITTLE CHANGE IN THE LOW LEVEL TEMP FIELDS...HAVE HIGHS SIMILAR TO SUNDAY WITH MOST AREAS UPPER 40S TO LOW 50S. TUESDAY/TUESDAY NIGHT...CONTINUED DRY AS A BRIEF PERIOD OF MID/UPPER RIDGING TRANSLATES OVERHEAD...AND AGAIN VERY SIMILAR HIGH TEMPERATURES AS PREVIOUS FEW DAYS WITH UPPER 40S MOST NEB ZONES AND LOW-MID 50S KS. WEDNESDAY...STILL NO LEGITIMATE SIGN OF PRECIP...AS MODELS ADVERTISE FAIRLY UNEVENTFUL QUASI-ZONAL FLOW AT THIS TIME. ONCE AGAIN...HIGHS RANGING UPPER 40S NORTHEAST TO MID-50S SOUTHWEST. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ 0956 PM UPDATE/AVIATION...BRYANT SHORT TERM...HEINLEIN LONG TERM...PFANNKUCH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
332 AM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... BACKEDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAILY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF TEH BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAYSHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... 06Z UPDATE... STRONG WET SYSTEM IS PROGRESSING THROUGH THE REGION. SSE WIND AHEAD OF THE FRONT...WITH STRONG SSW FLOW NOT FAR OFF THE SURFACE. FOR KRME AND KAVP...LIKELY MEETING LLWS THRESHOLD AND THUS INCLUDED INITIALLY IN TAFS. HOWEVER...SURFACE WIND WILL ABRUPTLY SHIFT TO SW WITH BRIEF HEAVY SHOWERS AS FRONT PASSES...WITH TIMING AS INDICATED IN TAFS. THOUGH IFR NOT OUT OF QUESTION WITH FRONT...MAINLY MVFR IS ANTICIPATED AND HAS OCCURRED UPSTREAM. BEHIND FRONT...WINDS WILL HAVE A MUCH EASIER TIME MIXING DOWN...MITIGATING ANY FURTHER LLWS BUT ALSO ALLOWING GUSTS FREQUENTLY IN THE 30-40 KT RANGE. KSYR-KRME COULD EVEN GET A BIT HIGHER THAN THAT THIS AFTERNOON. SCT-BKN CLOUD DECK DURING THE DAYTIME HOURS...EVENTUALLY WITH SCT -SHSN AND MVFR CIG FOR SOME TERMINALS. LAKE ONTARIO SNOW BAND WILL AT FIRST DEVELOP NORTH OF THE AREA THIS AFTERNOON...BUT SHOULD EDGE SOUTH ENOUGH TO INVOLVE KRME IN OCCASIONAL IFR VIS 00Z-06Z FRIDAY...AND NOT LONG AFTER THAT FOR KSYR. .OUTLOOK... LATE THU NGT THRU SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS 1 TO UP TO 2.5 INCHES WITH THE HEAVIEST RAIN AXIS FURTHER WEST ACROSS THE FINGER LAKES AND CHEMUNG BASINS OF NY. WILL HAVE TWO BATCHES WITH THE INITIAL BATCH ALREADY IN WRN PA AND WRN NY NOW. THIS FIRST BATCH MOVES QUICKLY THROUGH THIS AFTN. RAINFALL THIS AFTN UP TO HALF AN INCH. QUICK RESPONSE ON STREAMS BUT NO FLOODING INITIALLY. THE COLD FRONT WILL COME THROUGH LATE EVE AND EARLY MORNING WITH MORE HEAVY RAIN. ANOTHER QUICK INCH IN LESS THAN 6 HOURS WHICH WILL BE MOSTLY RUNOFF. STREAMS AND RIVERS WILL RESPOND QUICKLY. FLASH FLOODING POSSIBLE...FOLLOWED BY MINOR RIVER FLOODING. FLOOD WATCH CONTINUES FOR ENTIRE CWA STARTING AT 4 PM INTO THURSDAY MORNING. RIVER FLOOD WARNINGS JUST ISSUED FOR WEST BRANCH DELAWARE RIVER AT WALTON TIOUGHNIOGA RIVER AT CORTLAND CHENANGO RIVER AT SHERBURNE SUSQUEHANNA RIVER AT VESTAL SUSQUEHANNA RIVER AT WAVERLY/SAYRE SUSQUEHANNA RIVER AT TOWANDA SUSQUEHANNA RIVER AT MESHOPPEN SUSQUEHANNA RIVER NEAR WILKES-BARRE && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR PAZ038>040-043-044- 047-048-072. WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR NYZ009-015>018- 022>025-036-037-044>046-055>057-062. WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST FRIDAY FOR NYZ009. && $$ LONG TERM...MDP/TAC AVIATION...MDP HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1157 PM EST WED JAN 30 2013 .SYNOPSIS... RAIN...HEAVY AT TIMES WILL FALL ACROSS THE REGION TONIGHT AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE REGION WHICH WILL SEND TEMPERATURES BACK TO SEASONAL NORMALS. AS THE COLD AIR DEEPENS ON THURSDAY...LAKE EFFECT SNOWS WILL SET UP IN THE TRADITIONAL SNOWBELTS EAST AND SOUTHEAST OF THE LAKES...THEN WILL CONTINUE THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH THURSDAY/... LOW PRESSURE ACROSS LAKE HURON WILL LIFT NORTHEAST ACROSS SOUTHERN ONTARIO OVERNIGHT. THIS WILL BRING A COLD FRONT ACROSS THE REGION TONIGHT...FORECAST TO ENTER FAR WESTERN NEW YORK AROUND MIDNIGHT...THEN SWEEP RAPIDLY TO THE EAST THROUGH THE EARLY MORNING HOURS. THIS WILL CAUSE AN ABRUPT DROP IN TEMPERATURES...AND KEY THE ONSET IN GUSTY WINDS. EXPECT WIND GUSTS WILL PUSH 50 MPH IMMEDIATELY BEHIND THE FRONT...BEFORE THE STEADIER WINDS AHEAD OF A SECONDARY SHOT OF COLDER AIR. IN ADDITION....THIS SYSTEM WILL SET UP A DEEP SOUTHERLY FLOW OUT AHEAD OF IT...WHICH WILL TRANSPORT MOISTURE FROM PENNSYLVANIA AND INTO CENTRAL NEW YORK TONIGHT. A BLEND OF RADAR AND HRRR MODEL GUIDANCE THROUGH 1100 PM SUGGEST THE HEAVIEST RAINS WILL SLIDE A BIT FURTHER EAST...MAINLY IMPACTING LOCATIONS EAST OF LAKE ONTARIO. BECAUSE OF THIS...HAVE MODIFIED THE FLOOD WATCH. REFER TO THE HYDROLOGY SECTION FOR MORE ON THIS. THE SYSTEM WILL CAUSE MULTIPLE ISSUES FOR THE CWA...ORGANIZED BY IMPACT BELOW. 1. STRONG WINDS...THE AFOREMENTIONED STORM SYSTEM WILL DEEPEN FROM AROUND 985MB 00Z TONIGHT TO 970MB 12Z TOMORROW MORNING JUST NORTH OF VERMONT...AND THEN BELOW 960 MB BY 00Z FRIDAY ACROSS EASTERN QUEBEC. THIS RAPID DEEPENING...COMBINED WITH 6 TO 8 MB ISALLOBARIC PRESSURE RISES WITHIN COLD AIR ADVECTION FOLLOWING THE COLD FRONT SHOULD BE ABLE TO MIX A 50 KNOT JET AT 925 HPA DOWN TO THE SURFACE. GIVEN THE STRONG AND VERY DYNAMIC NATURE OF THIS SYSTEM...ITS ASSOCIATED WIND FIELDS WILL ALSO BE QUITE STRONG. WE WILL UPGRADE THE ADVISORY TO A WARNING FOR A GOOD PORTION OF THE CWA. WIND GUSTS UP TO 60 MPH ARE LIKELY IN FAVORED AREAS ALONG THE LAKE ERIE SHORELINE INLAND ACROSS SOUTHERN LAKE ONTARIO AND THROUGH THE EASTERN LAKE ONTARIO REGION. FOR OUR INLAND COUNTIES OF WYOMING...ALLEGANY...LIVINGSTON AND ONTARIO WE WILL LEAVE A HIGH END WIND ADVISORY AS THE DEEPENING LOW MAY BE TOO FAR NORTH TO ALLOW FOR WARNING CRITERIA WINDS HERE. 2. LAKE EFFECT SNOW...FOLLOWING THE PASSAGE OF THE COLD FRONT -14C TO -16C 850 HPA AIR TEMPERATURES WILL BE CROSSING THE LAKES. AT FIRST WINDS MAY BE TO STRONG FOR GOOD FORMATION OF LAKE EFFECT SNOW BANDS WITH THE WINDS SHEARING AWAY THE LAKE BAND FORMATION. ALSO WITH THE STRONG WINDS RESIDENT TIME OVER THE LAKE BODIES WILL BE LIMITED. AS WINDS DIMINISH THROUGH THE AFTERNOON AND COLD AIR DEEPENS...AND LAKE INDUCED EQUILIBRIUM LEVELS RISE TOWARDS 7 TO 9K FEET A BAND OF SNOW SHOULD BE FORMING OFF BOTH LAKE ERIE AND LAKE ONTARIO. THE NAM...AND TO A DEGREE THE GFS HAS DEEP SYNOPTIC MOISTURE REMAINING IN THE SNOW GROWTH ZONE...WHICH WILL BE FALLING WITH THE COLD AIR ADVECTION. OFF LAKE ONTARIO...WIND FIELD CONVERGENCE OVER LAKE ONTARIO IS LEADING TO IMPRESSIVE OMEGA FIELDS BY THURSDAY AFTERNOON WHERE A BAND OF LAKE EFFECT SNOW MAY BEGIN TO PRODUCE SNOWFALL RATES UP TO 2 INCHES PER HOUR. FOLLOWING THE SURFACE LOW AND UPPER LEVEL TROUGH WINDS WILL BEGIN TO VEER THROUGH THE DAY DROPPING THE LAKE EFFECT SNOW BAND SOUTH OF JEFFERSON COUNTY. FOR THIS REASON WILL LEAVE JEFFERSON COUNTY AS A HIGH END LAKE EFFECT SNOW ADVISORY...AND HAVE WARNINGS FOR LEWIS AND OSWEGO COUNTIES WHERE THE BAND WILL LIKELY FALL LONGER. OFF LAKE ERIE...A WESTERLY FLOW OVER THE STILL OPEN WATERS OF LAKE ERIE WILL BRING MULTI BANDED STRUCTURE SNOW BANDS ACROSS THE SOUTHERN TIER. CONFIDENCE IS GREATER ACROSS CHAUTAUQUA AND CATTARAUGUS COUNTIES THAN SOUTHERN ERIE AND WYOMING COUNTIES FOR WARNING CRITERIA SNOW. WILL UPGRADE THE WATCH TO A LAKE EFFECT WARNING ACROSS THE SOUTHERN TIER...WHILE LEAVING ADVISORIES FOR SOUTHERN TIER AND WYOMING COUNTIES. 3. REGARDING TEMPERATURES...RECORDED HIGHS WERE SHATTERED ACROSS MUCH OF THE REGION TODAY WITH MORNING AND EARLY AFTERNOON HIGHS REACHING NEAR 10 DEGREES ABOVE RECORD VALUES FOR THE DATE. THE NEW RECORDS FOR TODAY... BUFFALO.....66 (PREVIOUS WAS 56 IN 1916) ROCHESTER...64 (PREVIOUS WAS 55 IN 1974) WATERTOWN...63 (PREVIOUS WAS 52 IN 1995) THESE READINGS ARE STILL SEVERAL DEGREES SHY OF THE ALLTIME MONTHLY RECORD HIGH TEMPERATURE WHICH ARE AS FOLLOWS: BUFFALO.....72 IN 1950. ROCHESTER...74 IN 1950...CORRECTED WATERTOWN...66 IN 1995. THE COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT SENDING TEMPERATURES BACK TO SEASONAL NORMS...WITH MANY AREAS DOWN INTO THE UPPER 20S AND LOW 30S BY TOMORROW MORNING. WITH THE RAIN OVERNIGHT THE PROSPECTS FOR BLACK ICE WILL BE PRESENT AS WE QUICKLY COOL FURTHER INTO THE MID AND UPPER 20S BY MID MORNING. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... HEAVY LAKE EFFECT SNOWS SHOULD BE ONGOING ON A WESTERLY FLOW REGIME AT THE START OF THE PERIOD. BUFR PROFILES FROM THURSDAY NIGHT THROUGH AT LEAST THE DAYTIME HOURS OF FRIDAY CONTINUE TO LOOK RATHER IMPRESSIVE...AS A DEEP LAYERED CYCLONIC FLOW REGIME IS WELL ESTABLISHED. MOISTURE PROFILES LOOK QUITE ADEQUATE WITH SATURATION WELL UP THROUGH 10K FEET AND DEEPER AT TIMES AS A COUPLE OF REINFORCING WEAK SHORTWAVES WORK THROUGH THE MEAN WEST NORTHWEST FLOW. THE BIGGEST FACTOR THAT COULD LIMIT TOTALS WILL BE THE VEERING WINDS IN RESPONSE TO A SHORTWAVE CROSSING THE LOWER LAKES. THIS WILL TEND TO PUSH THE LAKE BANDS...ESPECIALLY ACROSS LAKE ONTARIO SOUTHWARD. THIS COULD BRING THE PRIME LAKE EFFECT FOCUS ALONG THE SOUTH SHORE OF LAKE ONTARIO...WHICH COULD BRING AT LEAST ADVISORY OR GREATER TOTALS TO THIS AREA INCLUDING THE ROCHESTER METRO AREA. FEEL A BIT MORE CONFIDENT WITH THE AREA FROM WAYNE OVER TO NORTHERN CAYUGA AT THIS POINT...THEREFORE WILL ISSUE A LAKE EFFECT SNOW WATCH FOR THAT AREA...BUT IT IS HIGHLY POSSIBLE THAT LAKE EFFECT HEADLINES MAY NEED TO BE ISSUED FARTHER TO THE WEST. ANOTHER SHORTWAVE APPROACHING THE REGION FRIDAY NIGHT AND SATURDAY MAY REORIENT THE LAKES SNOWS FOR A TIME NORTHWARD AS THE FLOW BACKS TO WEST SOUTHWEST...POTENTIALLY BRINGING SOME ACCUMULATING SNOWS INTO PORTIONS OF THE BUFFALO METRO AND WATERTOWN AREAS. THE PASSAGE OF THE SHORTWAVE SHOULD RE-ESTABLISH THE LAKE SNOWS BACK SOUTHWARD LATER SATURDAY AND SATURDAY NIGHT. MUCH COLDER AIR MASS ACROSS THE AREA FRIDAY AND SATURDAY WITH DAYTIME HIGHS IN THE TEENS AND 20S...WITH WIND CHILLS PERIODICALLY BELOW ZERO. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... THE VERY COLD AIR REMAINS IN PLACE SUNDAY...BEFORE A GRADUAL MODIFICATION OF THE AIR MASS OCCURS INTO EARLY NEXT WEEK AS THE UPPER TROUGH SHIFTS TO THE EAST. TWO CLIPPER TYPE WAVES LOOK TO IMPACT THE LOWER LAKES REGION DURING THIS TIME FRAME. ONE WAVE MOVES THROUGH ON SUNDAY WHICH MAY SERVE TO ENHANCE THE ONGOING LAKE EFFECT SNOWS IN A WESTERLY FLOW REGIME. THE SECOND WAVE LOOKS TO MOVE THROUGH LATE MONDAY OR EARLY TUESDAY AND APPEARS TO BE RATHER ROBUST AND GIVEN THE PROJECTED TRACK OF THE ASSOCIATED SURFACE LOW COULD BRING THE POTENTIAL FOR A GENERAL WIDESPREAD SEVERAL INCHES OF SNOW. BEHIND THIS WAKE A COLDER FLOW DEVELOPS WHICH MAY REDEVELOP SOME LAKE SNOWS BUT LACK OF SIGNIFICANT MOISTURE COULD LIMIT SNOWFALL POTENTIAL. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... A COLD FRONT ACROSS BUF/IAG/JHW AT 06Z WILL RACE TO THE EAST...REACHING ART AROUND 09Z. THIS FRONT WILL TRIGGER AN ABRUPT INCREASE IN WINDS...WHICH WILL LAST THROUGH MUCH OF THE DAY...BEFORE TAPERING OFF LATE THURSDAY AFTERNOON. MEANWHILE...RAIN SHOWER AHEAD OF THE FRONT WILL CONTINUE TO SLIDE EAST DURING THE EARLY MORNING HOURS. TEMPERATURES WILL COOL BEHIND THE FRONT...WHICH WILL SET UP LAKE SNOWS EAST OF THE LAKES. THESE SHOULD LARGELY MISS BUF/IAG/ROC FOR MOST OF TODAY AND THIS EVENING. LAKE SNOWS WILL PROBABLY IMPACT JHW/ART FOR A PERIOD...WITH IFR OR LOWER CONDITIONS POSSIBLE. OUTLOOK... THURSDAY NIGHT THROUGH SATURDAY...MVFR WITH LOCALIZED IFR IN LAKE EFFECT SNOW EAST OF THE LAKES. SUNDAY...MAINLY VFR WITH MVFR IN LOCALIZED LAKE EFFECT SNOW SHOWERS. MONDAY...VFR. && .MARINE... A COMPLEX AREA OF LOW PRESSURE FROM SOUTHERN CANADA AND THROUGH THE CENTRAL GREAT LAKES REGION THIS AFTERNOON WILL LIFT NORTHEASTWARD AND DEEPEN TONIGHT AND TOMORROW. A COLD FRONT SWINGING ACROSS THE LAKES...COUPLED WITH STRONG COLD AIR ADVECTION AND RAPID DEEPENING OF THE SURFACE LOW WILL INCREASE WINDS QUICKLY TO GALE FORCE FOLLOWING THE PASSAGE OF THE FRONT TONIGHT...WITH GALES THEN CONTINUING THROUGH MUCH OF THURSDAY. FOR THIS REASON...GALE WARNINGS WILL CONTINUE AS OUTLINED ON THE LAKES. WINDS AND WAVES WILL STILL REMAIN STRONG THURSDAY EVENING THROUGH SATURDAY...BEFORE DIMINISHING TO BELOW SMALL CRAFT CONDITIONS BY SATURDAY NIGHT. && .HYDROLOGY... FOLLOWING A BLEND OF RADAR AND NEAR TERM GUIDANCE...IT APPEARS THE STEADIEST RAINS WILL FALL EAST OF LAKE ONTARIO...WITH LESSER AMOUNTS WEST OF THE GENESEE RIVER. EAST OF LAKE ONTARIO...EXPECT AROUND AN INCH OF RAIN TO FALL...WITH LESS THAN THAT WEST OF THE GENESEE. LATEST RFC FORECASTS HAVE LOWERED CRESTS AT WELLSVILLE...WITH THE MAJORITY OF MMEFS GUIDANCE KEEPING THE BUFFALO CREEKS...GENESEE RIVER...AND ALLEGHENY RIVER BELOW FLOOD STAGE. THERE STILL MAY BE A FEW LINGERING ICE JAMS IN TYPICALLY FLOOD PRONE AREAS IN PARTS OF CHAUTAUQUA COUNTY. THERE STILL A THREAT FOR FLOODING IN EASTERN PORTIONS...WHERE AN INCH OF RAINFALL STILL APPEARS LIKELY. LOCALLY HIGHER AMOUNTS FROM CONVECTION AND/OR UPSLOPING MAY ALSO OCCUR. THIS COMBINED WITH SNOW MELT FROM LOCATIONS EAST OF LAKE ONTARIO WILL RESULT IN SIGNIFICANT RISES IN THE RIVERS AND CREEKS. AN INCH OF RAIN IS STILL MARGINAL TO CAUSE FLOODING...BUT WITH SNOW MELT QUITE DIFFICULT TO FORECAST...AND SOME ICE JAMS POSSIBLE...THERE IS A CONTINUED RISK OF FLOODING. THE SREF AND TO A LESSER EXTENT GFS/GGEM BASED MMEFS ENSEMBLES POINT TO THIS POTENTIAL. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HIGH WIND WARNING UNTIL 4 PM EST THURSDAY FOR NYZ001>008-010- 011-019-020-085. LAKE EFFECT SNOW ADVISORY FROM 10 AM THURSDAY TO 6 PM EST FRIDAY FOR NYZ012-085. LAKE EFFECT SNOW ADVISORY FROM 10 AM THURSDAY TO 1 AM EST FRIDAY FOR NYZ007. FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR NYZ004>008-014. LAKE EFFECT SNOW WARNING FROM 10 AM THURSDAY TO 6 PM EST FRIDAY FOR NYZ006-008-019-020. LAKE EFFECT SNOW WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON FOR NYZ004-005. WIND ADVISORY UNTIL 4 PM EST THURSDAY FOR NYZ012>014-021. MARINE...GALE WARNING UNTIL 4 PM EST THURSDAY FOR LEZ040-041. GALE WARNING UNTIL 10 AM EST THURSDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR LOZ030. GALE WARNING UNTIL 4 PM EST THURSDAY FOR LOZ042>045- 062>065. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...TMA LONG TERM...TMA AVIATION...APFFEL MARINE...APFFEL/THOMAS HYDROLOGY...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1112 PM EST WED JAN 30 2013 .SYNOPSIS... RAIN...HEAVY AT TIMES WILL FALL ACROSS THE REGION TONIGHT AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE REGION WHICH WILL SEND TEMPERATURES BACK TO SEASONAL NORMALS. AS THE COLD AIR DEEPENS ON THURSDAY...LAKE EFFECT SNOWS WILL SET UP IN THE TRADITIONAL SNOWBELTS EAST AND SOUTHEAST OF THE LAKES...THEN WILL CONTINUE THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH THURSDAY/... LOW PRESSURE ACROSS LAKE HURON WILL LIFT NORTHEAST ACROSS SOUTHERN ONTARIO OVERNIGHT. THIS WILL BRING A COLD FRONT ACROSS THE REGION TONIGHT...FORECAST TO ENTER FAR WESTERN NEW YORK AROUND MIDNIGHT...THEN SWEEP RAPIDLY TO THE EAST THROUGH THE EARLY MORNING HOURS. THIS WILL CAUSE AN ABRUPT DROP IN TEMPERATURES...AND KEY THE ONSET IN GUSTY WINDS. EXPECT WIND GUSTS WILL PUSH 50 MPH IMMEDIATELY BEHIND THE FRONT...BEFORE THE STEADIER WINDS AHEAD OF A SECONDARY SHOT OF COLDER AIR. IN ADDITION....THIS SYSTEM WILL SET UP A DEEP SOUTHERLY FLOW OUT AHEAD OF IT...WHICH WILL TRANSPORT MOISTURE FROM PENNSYLVANIA AND INTO CENTRAL NEW YORK TONIGHT. A BLEND OF RADAR AND HRRR MODEL GUIDANCE THROUGH 1100 PM SUGGEST THE HEAVIEST RAINS WILL SLIDE A BIT FURTHER EAST...MAINLY IMPACTING LOCATIONS EAST OF LAKE ONTARIO. BECAUSE OF THIS...HAVE MODIFIED THE FLOOD WATCH. REFER TO THE HYDROLOGY SECTION FOR MORE ON THIS. THE SYSTEM WILL CAUSE MULTIPLE ISSUES FOR THE CWA...ORGANIZED BY IMPACT BELOW. 1. STRONG WINDS...THE AFOREMENTIONED STORM SYSTEM WILL DEEPEN FROM AROUND 985MB 00Z TONIGHT TO 970MB 12Z TOMORROW MORNING JUST NORTH OF VERMONT...AND THEN BELOW 960 MB BY 00Z FRIDAY ACROSS EASTERN QUEBEC. THIS RAPID DEEPENING...COMBINED WITH 6 TO 8 MB ISALLOBARIC PRESSURE RISES WITHIN COLD AIR ADVECTION FOLLOWING THE COLD FRONT SHOULD BE ABLE TO MIX A 50 KNOT JET AT 925 HPA DOWN TO THE SURFACE. GIVEN THE STRONG AND VERY DYNAMIC NATURE OF THIS SYSTEM...ITS ASSOCIATED WIND FIELDS WILL ALSO BE QUITE STRONG. WE WILL UPGRADE THE ADVISORY TO A WARNING FOR A GOOD PORTION OF THE CWA. WIND GUSTS UP TO 60 MPH ARE LIKELY IN FAVORED AREAS ALONG THE LAKE ERIE SHORELINE INLAND ACROSS SOUTHERN LAKE ONTARIO AND THROUGH THE EASTERN LAKE ONTARIO REGION. FOR OUR INLAND COUNTIES OF WYOMING...ALLEGANY...LIVINGSTON AND ONTARIO WE WILL LEAVE A HIGH END WIND ADVISORY AS THE DEEPENING LOW MAY BE TOO FAR NORTH TO ALLOW FOR WARNING CRITERIA WINDS HERE. 2. LAKE EFFECT SNOW...FOLLOWING THE PASSAGE OF THE COLD FRONT -14C TO -16C 850 HPA AIR TEMPERATURES WILL BE CROSSING THE LAKES. AT FIRST WINDS MAY BE TO STRONG FOR GOOD FORMATION OF LAKE EFFECT SNOW BANDS WITH THE WINDS SHEARING AWAY THE LAKE BAND FORMATION. ALSO WITH THE STRONG WINDS RESIDENT TIME OVER THE LAKE BODIES WILL BE LIMITED. AS WINDS DIMINISH THROUGH THE AFTERNOON AND COLD AIR DEEPENS...AND LAKE INDUCED EQUILIBRIUM LEVELS RISE TOWARDS 7 TO 9K FEET A BAND OF SNOW SHOULD BE FORMING OFF BOTH LAKE ERIE AND LAKE ONTARIO. THE NAM...AND TO A DEGREE THE GFS HAS DEEP SYNOPTIC MOISTURE REMAINING IN THE SNOW GROWTH ZONE...WHICH WILL BE FALLING WITH THE COLD AIR ADVECTION. OFF LAKE ONTARIO...WIND FIELD CONVERGENCE OVER LAKE ONTARIO IS LEADING TO IMPRESSIVE OMEGA FIELDS BY THURSDAY AFTERNOON WHERE A BAND OF LAKE EFFECT SNOW MAY BEGIN TO PRODUCE SNOWFALL RATES UP TO 2 INCHES PER HOUR. FOLLOWING THE SURFACE LOW AND UPPER LEVEL TROUGH WINDS WILL BEGIN TO VEER THROUGH THE DAY DROPPING THE LAKE EFFECT SNOW BAND SOUTH OF JEFFERSON COUNTY. FOR THIS REASON WILL LEAVE JEFFERSON COUNTY AS A HIGH END LAKE EFFECT SNOW ADVISORY...AND HAVE WARNINGS FOR LEWIS AND OSWEGO COUNTIES WHERE THE BAND WILL LIKELY FALL LONGER. OFF LAKE ERIE...A WESTERLY FLOW OVER THE STILL OPEN WATERS OF LAKE ERIE WILL BRING MULTI BANDED STRUCTURE SNOW BANDS ACROSS THE SOUTHERN TIER. CONFIDENCE IS GREATER ACROSS CHAUTAUQUA AND CATTARAUGUS COUNTIES THAN SOUTHERN ERIE AND WYOMING COUNTIES FOR WARNING CRITERIA SNOW. WILL UPGRADE THE WATCH TO A LAKE EFFECT WARNING ACROSS THE SOUTHERN TIER...WHILE LEAVING ADVISORIES FOR SOUTHERN TIER AND WYOMING COUNTIES. 3. REGARDING TEMPERATURES...RECORDED HIGHS WERE SHATTERED ACROSS MUCH OF THE REGION TODAY WITH MORNING AND EARLY AFTERNOON HIGHS REACHING NEAR 10 DEGREES ABOVE RECORD VALUES FOR THE DATE. THE NEW RECORDS FOR TODAY... BUFFALO.....66 (PREVIOUS WAS 56 IN 1916) ROCHESTER...64 (PREVIOUS WAS 55 IN 1974) WATERTOWN...63 (PREVIOUS WAS 52 IN 1995) THESE READINGS ARE STILL SEVERAL DEGREES SHY OF THE ALLTIME MONTHLY RECORD HIGH TEMPERATURE WHICH ARE AS FOLLOWS: BUFFALO.....72 IN 1950. ROCHESTER...74 IN 1950...CORRECTED WATERTOWN...66 IN 1995. THE COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT SENDING TEMPERATURES BACK TO SEASONAL NORMS...WITH MANY AREAS DOWN INTO THE UPPER 20S AND LOW 30S BY TOMORROW MORNING. WITH THE RAIN OVERNIGHT THE PROSPECTS FOR BLACK ICE WILL BE PRESENT AS WE QUICKLY COOL FURTHER INTO THE MID AND UPPER 20S BY MID MORNING. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... HEAVY LAKE EFFECT SNOWS SHOULD BE ONGOING ON A WESTERLY FLOW REGIME AT THE START OF THE PERIOD. BUFR PROFILES FROM THURSDAY NIGHT THROUGH AT LEAST THE DAYTIME HOURS OF FRIDAY CONTINUE TO LOOK RATHER IMPRESSIVE...AS A DEEP LAYERED CYCLONIC FLOW REGIME IS WELL ESTABLISHED. MOISTURE PROFILES LOOK QUITE ADEQUATE WITH SATURATION WELL UP THROUGH 10K FEET AND DEEPER AT TIMES AS A COUPLE OF REINFORCING WEAK SHORTWAVES WORK THROUGH THE MEAN WEST NORTHWEST FLOW. THE BIGGEST FACTOR THAT COULD LIMIT TOTALS WILL BE THE VEERING WINDS IN RESPONSE TO A SHORTWAVE CROSSING THE LOWER LAKES. THIS WILL TEND TO PUSH THE LAKE BANDS...ESPECIALLY ACROSS LAKE ONTARIO SOUTHWARD. THIS COULD BRING THE PRIME LAKE EFFECT FOCUS ALONG THE SOUTH SHORE OF LAKE ONTARIO...WHICH COULD BRING AT LEAST ADVISORY OR GREATER TOTALS TO THIS AREA INCLUDING THE ROCHESTER METRO AREA. FEEL A BIT MORE CONFIDENT WITH THE AREA FROM WAYNE OVER TO NORTHERN CAYUGA AT THIS POINT...THEREFORE WILL ISSUE A LAKE EFFECT SNOW WATCH FOR THAT AREA...BUT IT IS HIGHLY POSSIBLE THAT LAKE EFFECT HEADLINES MAY NEED TO BE ISSUED FARTHER TO THE WEST. ANOTHER SHORTWAVE APPROACHING THE REGION FRIDAY NIGHT AND SATURDAY MAY REORIENT THE LAKES SNOWS FOR A TIME NORTHWARD AS THE FLOW BACKS TO WEST SOUTHWEST...POTENTIALLY BRINGING SOME ACCUMULATING SNOWS INTO PORTIONS OF THE BUFFALO METRO AND WATERTOWN AREAS. THE PASSAGE OF THE SHORTWAVE SHOULD RE-ESTABLISH THE LAKE SNOWS BACK SOUTHWARD LATER SATURDAY AND SATURDAY NIGHT. MUCH COLDER AIR MASS ACROSS THE AREA FRIDAY AND SATURDAY WITH DAYTIME HIGHS IN THE TEENS AND 20S...WITH WIND CHILLS PERIODICALLY BELOW ZERO. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... THE VERY COLD AIR REMAINS IN PLACE SUNDAY...BEFORE A GRADUAL MODIFICATION OF THE AIR MASS OCCURS INTO EARLY NEXT WEEK AS THE UPPER TROUGH SHIFTS TO THE EAST. TWO CLIPPER TYPE WAVES LOOK TO IMPACT THE LOWER LAKES REGION DURING THIS TIME FRAME. ONE WAVE MOVES THROUGH ON SUNDAY WHICH MAY SERVE TO ENHANCE THE ONGOING LAKE EFFECT SNOWS IN A WESTERLY FLOW REGIME. THE SECOND WAVE LOOKS TO MOVE THROUGH LATE MONDAY OR EARLY TUESDAY AND APPEARS TO BE RATHER ROBUST AND GIVEN THE PROJECTED TRACK OF THE ASSOCIATED SURFACE LOW COULD BRING THE POTENTIAL FOR A GENERAL WIDESPREAD SEVERAL INCHES OF SNOW. BEHIND THIS WAKE A COLDER FLOW DEVELOPS WHICH MAY REDEVELOP SOME LAKE SNOWS BUT LACK OF SIGNIFICANT MOISTURE COULD LIMIT SNOWFALL POTENTIAL. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... A BROAD AREA OF SHOWERS WILL MOVE INTO THE REGION...BOTH STREAMING FROM THE SOUTH AND AHEAD OF A COLD FRONT. THIS WILL BRING A PERIOD OF RAIN TO ALL TAF SITES...BUT WITH THE SOUTHERLY DOWNSLOPE COMPONENT TO THE FLOW CIGS WILL BE INITIALLY SLOW TO DROP. AS THE COLD FRONT CROSS THE AREA BETWEEN 04Z AND 09Z...CIGS WILL DROP AND IFR CONDITIONS WILL BECOME MORE WIDESPREAD...ESPECIALLY DOWNWIND OF THE LAKES. RAIN WILL MIX WITH...THEN CHANGE TO SNOW BEFORE DAYBREAK THURSDAY. STRONG COLD AIR ADVECTION BEHIND THE DEPARTING FRONT WILL INCREASE MIXING AND RAPIDLY STRENGTHEN WESTERLY WINDS OVERNIGHT. LATE TONIGHT INTO THURSDAY MORNING...EXPECT WINDS TO GUST TO 40-50 KNOTS IN MOST LOCATIONS...BEFORE TAPERING OFF LATE THURSDAY AFTERNOON. LAKE SNOWS WILL DEVELOP EAST OF THE LAKES. THESE WILL LIKELY STAY OUT OF BUF/IAG/ROC...BUT SHOULD IMPACT ART/JHW FOR A PERIOD. CONDITIONS WILL VARY SIGNIFICANTLY IN AND OUT OF LAKE EFFECT BANDS. OUTLOOK... THURSDAY NIGHT THROUGH SATURDAY...MVFR WITH LOCALIZED IFR IN LAKE EFFECT SNOW EAST OF THE LAKES. SUNDAY...MAINLY VFR WITH MVFR IN LOCALIZED LAKE EFFECT SNOW SHOWERS. MONDAY...VFR. && .MARINE... A COMPLEX AREA OF LOW PRESSURE FROM SOUTHERN CANADA AND THROUGH THE CENTRAL GREAT LAKES REGION THIS AFTERNOON WILL LIFT NORTHEASTWARD AND DEEPEN TONIGHT AND TOMORROW. A COLD FRONT SWINGING ACROSS THE LAKES...COUPLED WITH STRONG COLD AIR ADVECTION AND RAPID DEEPENING OF THE SURFACE LOW WILL INCREASE WINDS QUICKLY TO GALE FORCE FOLLOWING THE PASSAGE OF THE FRONT TONIGHT...WITH GALES THEN CONTINUING THROUGH MUCH OF THURSDAY. FOR THIS REASON...GALE WARNINGS WILL CONTINUE AS OUTLINED ON THE LAKES. WINDS AND WAVES WILL STILL REMAIN STRONG THURSDAY EVENING THROUGH SATURDAY...BEFORE DIMINISHING TO BELOW SMALL CRAFT CONDITIONS BY SATURDAY NIGHT. && .HYDROLOGY... FOLLOWING A BLEND OF RADAR AND NEAR TERM GUIDANCE...IT APPEARS THE STEADIEST RAINS WILL FALL EAST OF LAKE ONTARIO...WITH LESSER AMOUNTS WEST OF THE GENESEE RIVER. EAST OF LAKE ONTARIO...EXPECT AROUND AN INCH OF RAIN TO FALL...WITH LESS THAN THAT WEST OF THE GENESEE. LATEST RFC FORECASTS HAVE LOWERED CRESTS AT WELLSVILLE...WITH THE MAJORITY OF MMEFS GUIDANCE KEEPING THE BUFFALO CREEKS...GENESEE RIVER...AND ALLEGHENY RIVER BELOW FLOOD STAGE. THERE STILL MAY BE A FEW LINGERING ICE JAMS IN TYPICALLY FLOOD PRONE AREAS IN PARTS OF CHAUTAUQUA COUNTY. THERE STILL A THREAT FOR FLOODING IN EASTERN PORTIONS...WHERE AN INCH OF RAINFALL STILL APPEARS LIKELY. LOCALLY HIGHER AMOUNTS FROM CONVECTION AND/OR UPSLOPING MAY ALSO OCCUR. THIS COMBINED WITH SNOW MELT FROM LOCATIONS EAST OF LAKE ONTARIO WILL RESULT IN SIGNIFICANT RISES IN THE RIVERS AND CREEKS. AN INCH OF RAIN IS STILL MARGINAL TO CAUSE FLOODING...BUT WITH SNOW MELT QUITE DIFFICULT TO FORECAST...AND SOME ICE JAMS POSSIBLE...THERE IS A CONTINUED RISK OF FLOODING. THE SREF AND TO A LESSER EXTENT GFS/GGEM BASED MMEFS ENSEMBLES POINT TO THIS POTENTIAL. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HIGH WIND WARNING UNTIL 4 PM EST THURSDAY FOR NYZ001>008-010- 011-019-020-085. LAKE EFFECT SNOW ADVISORY FROM 10 AM THURSDAY TO 6 PM EST FRIDAY FOR NYZ012-085. LAKE EFFECT SNOW ADVISORY FROM 10 AM THURSDAY TO 1 AM EST FRIDAY FOR NYZ007. FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR NYZ004>008-014. LAKE EFFECT SNOW WARNING FROM 10 AM THURSDAY TO 6 PM EST FRIDAY FOR NYZ006-008-019-020. LAKE EFFECT SNOW WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON FOR NYZ004-005. WIND ADVISORY UNTIL 4 PM EST THURSDAY FOR NYZ012>014-021. MARINE...GALE WARNING UNTIL 4 PM EST THURSDAY FOR LEZ040-041. GALE WARNING UNTIL 10 AM EST THURSDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR LOZ030. GALE WARNING UNTIL 4 PM EST THURSDAY FOR LOZ042>045- 062>065. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...TMA LONG TERM...TMA AVIATION...APFFEL MARINE...APFFEL/THOMAS HYDROLOGY...APFFEL
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
204 AM MST THU JAN 31 2013 .UPDATE... ISSUED AT 201 AM MST THU JAN 31 2013 AS OF 2 AM...RADAR AND WEBCAMS CONTINUE TO SHOW SNOW BANDS PERSISTING OVER GLENWOOD SPRINGS AND THROUGH GLENWOOD CANYON. LATEST HRRR AND RAP SHOW SNOW CONTINUING THROUGH 15Z WITH SNOW RAPIDLY DROPPING OFF AFTERWARDS. THIS CORRESPONDS WELL WITH TIME HEIGHTS OVER GLENWOOD CANYON SHOWING DEEP SATURATED LAYER IN THE DENDRITIC GROWTH ZONE WITH DECENT UPWARD MOTION PERSISTING THROUGH 15Z BEFORE THE PROFILE DRIES OUT. THEREFORE...EXTENDED THE WINTER WEATHER ADVISORY FOR COZ008 THROUGH 15Z THIS MORNING. UPDATE ISSUED AT 1130 PM MST WED JAN 30 2013 BASED ON RADAR AND SATELLITE OBSERVATIONS...THE PERSISTENT SNOW BANDS THAT BROUGHT SNOW TO THE I-70 CORRIDOR HAVE SHIFTED EASTWARD WITH CONDITIONS IMPROVING FROM RIFLE TO SILT BASED ON OBSERVATIONS AND WEBCAMS. THIS IS CONSISTENT WITH THE LATEST RAP DATA SHOWING LITTLE IF ANY ADDITIONAL ACCUMULATIONS HERE. THEREFORE CANCELLED THE WINTER WEATHER ADVISORY FOR COZ007. WEBCAMS AND RADAR STILL SHOW SNOW BANDS STREAMING ACROSS THE FLATTOPS...THE I-70 CORRIDOR FROM GLENWOOD SPRINGS TO VAIL PASS...AND STEAMBOAT. REMAINING HIGHLITES LOOK ON TRACK. UPDATE ISSUED AT 536 PM MST WED JAN 30 2013 PERSISTENT SNOW OVER THE I-70 CORRIDOR WEST OF EAGLE AND EAST OF PALISADE HAD ALREADY BROUGHT 1 TO 2 INCHES OF SNOW TO THESE AREAS EARLY THIS EVENING. LATEST NAM12 AND RAP13 DATA INDICATED THIS PERSISTENT BAND OF SNOW COULD LAST THROUGH THE EVENING BRINGING FROM 2 TO 5 INCHES OF BY EARLY MORNING. THEREFORE...A WINTER WEATHER ADVISORY HAS BEEN ISSUED ZONES 7 AND 8. AREAS IN ZONE 8 ARE NOT INCLUDED IN THIS ADVISORY. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 302 PM MST WED JAN 30 2013 SNOW AND WIND IMPACTING THE NERN PART OF THE FORECAST AREA TODAY. CLASSIC OROGRAPHIC SNOW IN NORTHWEST FLOW AS PACIFIC MOISTURE AND STRONG JET TARGETS THE PARK/GORE RANGES AND THE FLAT TOP MOUNTAINS. MT WERNER SENSORS SHOW WIND OF 25 MPH BUT GUSTS TO AROUND 40 MPH. GIVEN LOW SNOW TO LIQUID RATIO VALUES...WEB CAMS SHOWING POOR VISIBILITY OVER THE MOUNTAIN PASSES. SNOTEL SITES SHOWING 6 HOUR QPF GENERALLY RANGING FROM /0.20/ TO /0.50/ INCHES...BUT THIS MAY EQUATE TO 5 TO 13 INCHES OF SNOW IF LIQUID TO WATER RATIO IS AROUND 25:1 OR HIGHER. THE HEAVIEST SNOW APPEARS CONFINED ABOVE 8500 FEET...OBSERVATIONS FROM THE PUBLIC AND SPOTTER REPORTS SUGGEST ONLY LIGHT SNOW IN THE MOUNTAIN VALLEYS (FROM MARBLE AND ASPEN). MODEL DATA KEEPS MOISTURE STREAM AND OROGRAPHIC SNOW ONGOING THROUGH THE NIGHT...BUT GRADUALLY TAPERS OFF ON THURSDAY. GRADIENT FLOW DOES WEAKEN ON THURSDAY WITH MOISTURE STREAM SOMEWHAT WEAKER...THEREFORE EXPECT SNOWFALL RATES TO DIMINISH ON THURSDAY. NO CHANGES TO THE CURRENT WINTER STORM WARNINGS AS ACCUMULATING SNOWFALL COMBINED WITH WIND WILL PERSIST INTO THURSDAY. IN ADDITION...AN EMBEDDED DISTURBANCE IN NORTHWEST FLOW RACES ACROSS THE NRN DIVIDE MOUNTAINS LATE THURSDAY AFTERNOON. ONCE THIS SHORT WAVE CROSSES THE DIVIDE...EXPECT SNOW AND WIND TO TAPER OFF CONSIDERABLY. FOR THE REMAINDER OF THE FORECAST AREA...MUCH OF EASTERN UTAH AND EXTREME WRN COLORADO WILL BE DRY. EXTENSIVE CLOUD COVER THAT COVERS MUCH OF THE REGION TODAY WILL GRADUALLY ERODE AWAY. MORE SUN EXPECTED ON THURSDAY ACROSS THE SWRN HALF OF THE FORECAST AREA. WITH LESS CLOUD COVER... EXPECT OVERNIGHT TEMPS ON FRIDAY MORNING TO BE THE COLDEST OF THE WEEK FOR THE NRN AND CENTRAL VALLEYS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 302 PM MST WED JAN 30 2013 A WAVE IN NW FLOW WILL CLIP NW CO FRI AS IT MOVES INTO THE PLAINS. THE GFS/ECMWF/CANADIAN MODELS IN GENERAL AGREEMENT HERE AND HAVE BOOSTED POPS FOR THE ELKHEAD AND PARK RANGES BASED ON THIS. A PERIOD OF Q-FORCING ALOFT WITH WARM ADVECTIVE UPLIFT AT MTN TOP LEVEL AND WITH W-NW OROGRAPHICS SHOULD RESULT IN SOME AREAS OF SNOW FROM ABOUT MIDDAY FRI INTO FRI EVENING. THIS WEEKEND LOOKS DRY AS THE WEST COAST RIDGE SLIDES OVER THE FORECAST AREA. A SMALL CLOSED LOW CURRENTLY DEVELOPING OFF THE CA COAST IS FORECAST TO SHEAR INLAND AND WEAKEN WHILE A LARGER PACIFIC TROUGH SPLITS AS IT APPROACHES THE COAST. THIS MORNING/S MODELS WERE IN GENERAL AGREEMENT WITH TAKING THE SOUTHERN PORTION OF THE SPLIT AND FORMING A CUT-OFF LOW WELL OFF THE CA COAST...WHILE THE NORTHERN SPLIT BRUSHES OUR FORECAST ABOUT SUNDAY. NEITHER THE GFS NOR ECMWF SHOW MUCH CHANCE OF SIGNIFICANT PRECIPITATION THOUGH FROM THE NORTHERN WAVE THOUGH. GFS HAS BEEN INCONSISTENT HANDLING THE SOUTHERN SPLIT CUT-OFF LOW...ALTERNATING BETWEEN BRINGING TO ABOUT THE 4 CORNERS BY TUE AND KEEPING IT OFFSHORE INLINE WITH THE MORE CONSISTENT ECMWF. FOLLOWING MORE THE PREFERRED ECMWF WOULD RESULT IN GENERAL RIDGING OVER ERN UT/WRN CO EARLY NEXT WEEK AND A MINIMAL CHANCE OF PRECIP. BUT BOTH THE GFS AND ECMWF SHOW A DECENT TROUGH APPROACHING THE PACIFIC NW COASTLINE ON WEDNESDAY...FOR POTENTIALLY UNSETTLED WEATHER LATE NEXT WEEK. TEMPERATURES ARE EXPECTED TO GRADUALLY MODERATE THIS PERIOD ALTHOUGH TEMPS WILL STILL BE A BIT OF A CHALLENGE IN MANY VALLEYS. SNOW COVER WILL KEEP TEMPS IN THE EASTERN UINTA BASIN LAGGING THE MOST BEHIND...HOWEVER...WHERE AN INVERSION SHOULD BE SLOW TO ERODE. INVERSIONS WILL NOT BE A STRONG FOR THE GRAND VALLEY WHERE SNOW COVER IS DIMINISHING IN AREAL EXTENT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1015 PM MST WED JAN 30 2013 A PERSISTENT MOIST NORTHWEST FLOW WILL CONTINUE TO DELIVER SNOW TO THE NORTHERN AND CENTRAL MOUNTAINS AND ADJACENT VALLEYS DURING THE REMAINDER OF THE NIGHT. AS A RESULT...EXPECT KSBS AND KASE TO HAVE PERSISTENT MVFR CIGS AND VSBY WITH OCCASIONAL IFR CONDITIONS DURING MUCH OF THE REMAINDER OF THE NIGHT WITH SURROUNDING MOUNTAINS OBSCURED IN SNOW. KRIL...KGWS...AND KGUC WILL HAVE OCCASIONAL MVFR CIGS AND VSBY IN SNOW SHOWERS THROUGH 12Z THURSDAY. MODELS CONTINUE TO GENERATE MOUNTAIN SNOW OVER THE NORTHERN AND CENTRAL MOUNTAINS THURSDAY THROUGH MIDNIGHT...THOUGH LIGHTER IN INTENSITY AND LESS EXTENSIVE. ADJACENT TERMINALS ARE UNLIKELY TO DROP BELOW VFR CONDITIONS THURSDAY. AREAS WEST OF A KPSO TO KCAG LINE WILL HAVE VFR CONDITIONS THROUGH THE NEXT 24 HOURS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING FOR COZ008. WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR COZ004-005- 010-013. UT...NONE. && $$ UPDATE...MDA SHORT TERM...PF LONG TERM...JAD AVIATION...NL
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1006 AM EST Thu Jan 31 2013 ...Possible short duration light freeze tonight... ...Another freeze possible Friday night... .NEAR TERM [Through Tonight]... Updated at 945 am EST- The 12 UTC regional surface analysis showed the cold front that moved through our forecast area last night was over South FL, while a 1024 mb high pressure ridge (centered over LA) was building east along the Gulf Coast. Vapor imagery and upper air data showed a broad trough over much of the eastern CONUS, with plenty of dry air throughout the atmospheric column. Based on our 12 UTC KTAE sounding and the latest NWP guidance, we expect high temperatures today will be in the mid to upper 50s. With the ridge building in quickly, surface winds will likely become calm shortly after sunset. This will allow for rapid cooling, and a light freeze is possible at our normally coldest sites (inland, relatively "open" areas away from cities). Even for those areas that don`t quite reach freezing, frost will be possible. The one limiting factor (which could prevent a deeper freeze) will be the potential for surface winds to increase slightly shortly before dawn, ahead of a dry cold front just to the north. && .SHORT TERM [Friday Through Saturday]... High Temps both Friday and Saturday will be slightly below climatology and generally range from the upper 50s NW to the mid 60s SE. On Friday night, however, we could see one of the coldest nights of the entire Winter Season thus far, as the Sfc Ridge behind the Dry Cold Front will be positioned right overhead of the CWA. This will allow for nearly ideal conditions for Radiational Cooling with clear skies and near calm winds. Low Temps could bottom out in the middle 20s over much of the interior, which will result in at least a long duration light freeze, and the possibility of the first Hard Freeze of the season. Therefore, all outdoor interests and those with sensitive vegetation should keep abreast of the latest information from the National Weather Service in Tallahassee. && .Long Term [Sunday night through Thursday]... Undated at 945 am EST- Mostly zonal flow will dominate on the southern periphery of broad eastern U.S. troughing through the period. A weak impulse will pass overhead late on Monday, however, dry air will limit the impacts to passing high clouds with no chance for rain. A slightly stronger mid/upper wave will approach towards the end of the period. At this time, little to no rain is expected with this disturbance either. Overall, the period will be dominated by dry conditions and near or slightly above average temperatures. && .AVIATION [through 18 UTC Friday]... Undated at 945 am EST- Unlimited visibility and ceilings will prevail through the period. Winds will be NW 5 to 10 KT this afternoon, light overnight, then NW 5 to 10 KT again Friday. The only possible visibility restriction could be caused by any large fire occurring near a terminal, but currently we don`t see any "hot spots" on satellite/radar imagery that would concern us. && .MARINE... Updated at 945 am EST- Winds & seas were still solidly at advisory levels, but the latest NWP guidance (including high resolution RAP and local 4km WRF) is unanimous in having the winds fall below advisory criteria by early afternoon. Thereafter, light to moderate offshore winds and seas will dominate through Friday, with a period of cautionary northeasterly winds expected on Friday night. Then, light winds and low seas are anticipated for the upcoming weekend and beginning of next week. && .FIRE WEATHER... Very dry conditions will overspread the region today and continue into the weekend. Red flag conditions look like a near certainty across much of North Florida today and possibly again on Friday. Though RH values will be below 25 percent in Alabama and Georgia today and on Friday, it appears as though the other required criteria (winds and/or fuel moisture) will not be met. More moist conditions will return by Sunday, putting an end to any red flag concerns. && .HYDROLOGY... Despite a fairly widespread rainfall across the region on Wednesday (with most areas receiving between 0.50" and 2" of rain, with the highest amounts well to the N and W), only minor rises have been observed on area rivers thus far. The only exception appears to be the Choctawhatchee River, where the river may rise to near action stage at Caryville during the next few days. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 58 32 63 25 63 / 0 0 0 0 0 Panama City 57 42 61 36 61 / 0 0 0 0 0 Dothan 56 36 57 28 60 / 0 0 0 0 0 Albany 56 32 57 26 60 / 0 0 0 0 0 Valdosta 57 32 61 25 62 / 0 0 0 0 0 Cross City 60 30 66 26 65 / 0 0 0 0 0 Apalachicola 57 40 62 35 59 / 0 0 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FREEZE WATCH from late tonight through Friday morning for Calhoun-Central Walton-Coastal Dixie-Coastal Taylor- Gadsden-Holmes-Inland Bay-Inland Dixie-Inland Franklin- Inland Gulf-Inland Jefferson-Inland Taylor-Inland Wakulla- Inland Walton-Jackson-Lafayette-Leon-Liberty-Madison- Washington. RED FLAG WARNING until 7 PM EST /6 PM CST/ this evening for Calhoun-Central Walton-Coastal Bay-Coastal Dixie-Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-Holmes- Inland Bay-Inland Dixie-Inland Jefferson-Inland Taylor- Inland Wakulla-Inland Walton-Jackson-Lafayette-Leon- Liberty-Madison-South Walton-Washington. FIRE WEATHER WATCH from Friday afternoon through Friday evening for Calhoun-Central Walton-Coastal Bay-Coastal Dixie-Coastal Franklin-Coastal Gulf-Coastal Jefferson- Coastal Taylor-Coastal Wakulla-Gadsden-Holmes-Inland Bay- Inland Dixie-Inland Franklin-Inland Gulf-Inland Jefferson- Inland Taylor-Inland Wakulla-Inland Walton-Jackson- Lafayette-Leon-Liberty-Madison-South Walton-Washington. GA...FREEZE WATCH from late tonight through Friday morning for Baker-Ben Hill-Berrien-Brooks-Calhoun-Clay-Colquitt-Cook- Decatur-Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes- Miller-Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas- Tift-Turner-Worth. AL...FREEZE WATCH from late tonight through Friday morning for Coffee-Dale-Geneva-Henry-Houston. GM...SMALL CRAFT ADVISORY until 1 PM EST this afternoon for Apalachee Bay or Coastal Waters From Keaton Beach to Ochlockonee River Fl out to 20 Nm-Coastal Waters From Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal waters from Suwannee River to Keaton Beach out 20 NM- Coastal waters from Apalachicola to Destin FL out 20 NM- Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Destin FL from 20 to 60 NM. && $$ NEAR TERM...Fournier SHORT TERM...Gould LONG TERM...Harrigan AVIATION...Fournier MARINE...Fournier/Gould FIRE WEATHER...Fournier/Gould HYDROLOGY...Gould
AREA FORECAST DISCUSSION
NWS GOODLAND KS
448 AM MST THU JAN 31 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 412 AM MST THU JAN 31 2013 FORECAST PROBLEMS WILL PROBLEMATIC TEMPERATURE FORECAST INTO TONIGHT AND HOW MUCH TO WARM UP THE HIGH TEMPERATURES INTO SATURDAY. SATELLITE SHOWING A BROAD UPPER TROUGH OVER THE TROUGH OVER THE WESTERN AND CENTRAL PACIFIC WITH A RIDGE ALONG THE WEST COAST OF NORTH AMERICA. A COUPLE OF SYSTEMS COMING INTO THE RIDGE ARE BEATING IT DOWN. A STRONG AND COLD SYSTEM IS DIGGING INTO THE NORTH CENTRAL PORTION OF THE COUNTRY. VERY COLD AIR MASS HAS MOVED FURTHER SOUTH FROM YESTERDAY AND IS NOT TOO FAR NORTH AND EAST OF OUR AREA. MODELS INITIALIZED WELL AT JET LEVEL WITH THE CANADIAN...GFS...AND NAM DOING THE BEST. MODELS INITIALIZED WELL AT MID LEVELS WITH THE GFS...CANADIAN...AND NAM DOING SLIGHTLY BETTER. LARGER SCALE MODELS DO NOT HAVE THE BACKDOOR COLD FRONT FAR ENOUGH SOUTH AND WEST BY 06Z...OH SURPRISE. THE RUC HAS CONTINUED TO GET BETTER AS THE NIGHT HAS PROGRESSED. OUTSIDE OF THE RUC ON THE LOW LEVEL THERMAL FIELD...THE ECMWF AND GFS WERE DOING A LITTLE BETTER THAN THE UKMET AND NAM. TODAY/TONIGHT...VERY THICK CLOUD COVER HAS SPREAD OVER THE AREA THROUGH THE NIGHT. WHAT THIS HAS DONE HAS PREVENTED ANY FALL OF THE TEMPERATURES AND IN FACT HAS CAUSED THE TEMPERATURES TO RISE SOME. NWP OUTPUT MUST BE UNDERDOING THIS CLOUD COVER AND IS TOO COOL WITH TEMPERATURES. THIS CLOUD COVER IS BEING CAUSED BY STRONG MID TO UPPER LEVEL JET. SOUNDINGS AND PLAN VIEW RELATIVE HUMIDITY PLOTS SHOW THIS CLOUD COVER LASTING MOST OF THE DAY...ESPECIALLY IN THE NORTHEAST PORTION. BACKDOOR COLD FRONT WITH VERY COLD AIR BEHIND IT HAS BEEN MOVING STEADILY TOWARD THE AREA THROUGH THE NIGHT AND IS NOT THAT FAR AWAY. RUC IS CATCHING ONTO THIS AT THIS TIME. INITIALLY WAS GOING TO CUT HIGH TEMPERATURES FROM GOING FORECAST BUT CLOUD COVER HAS COMPLICATED THAT. SO WILL BE STARTING MUCH WARMER THAN WHAT MOST OF THE MODELS SAY. FRONT SAGS ACROSS THE AREA THROUGH THE DAY WITH SOME LOCATIONS IN THE NORTHEAST HALF TO TWO THIRDS REACHING THEIR MAX BY 18Z. SO COMBINING REALITY AND THE RUC ADJUSTED MAX TEMPERATURES UP BUT HAVE EXTREMELY LOW CONFIDENCE ABOUT THIS. DID NOT GOES AS WARM AS IT BECAUSE OF THE CLOUD COVER. HRRR WOULD INDICATE HIGH TEMPERATURES ABOUT 10 DEGREES WARMER IN THE SOUTHWEST PORTION OF THE AREA THAT WHAT I HAVE. LEFT FRONT QUADRANT OF INCOMING JET WILL CONTINUE TO AFFECT THE NORTHEAST HALF TO TWO THIRDS OF THE AREA INTO EARLY AFTERNOON. SEVERAL STATIONS HAVE REPORTED BRIEF PERIODS OF FLURRIES. ALL MODEL OUTPUT AGREES IN PLACING LIGHT QPF IN THE ABOVE MENTIONED AREA. SREF PROBABILITIES AGREE WITH THAT. IT MAKES SENSE WITH THE JET... MESOSCALE FORCING AND LAPSE RATES IN PLACE. HOWEVER...DRIER AIR IN THE LOWEST LAYERS. SO INTRODUCED SCATTERED FLURRIES THROUGH MIDDAY WHEN THE FORCING AND MOISTURE LEAVE. PROBLEMATIC MIN FORECAST AS WELL. WINDS SHIFT AROUND TO A SOUTH DIRECTION PRETTY QUICKLY. NAM IS THE MOST AGGRESSIVE BUT IS SUPPORTED BY OTHER MODEL OUTPUT IN BRINGING STRATUS AND FOG DURING THE LATE EVENING AND OVERNIGHT HOURS. THIS IS AS THE COLD FRONT RETREATS BACK AS A WARM FRONT AND ALL THE MODELS ARE VERY SIMILAR IN DOING IT. MINS WILL PROBABLY BE REACHED IN THE EVENING ESPECIALLY IN THE WEST AND POSSIBLY IN THE SOUTH AND A NON-DIURNAL CURVE WILL HAVE TO BE INTRODUCED. BELIEVE MODELS ARE TOO COOL AND WENT ABOVE THE GUIDANCE. 06Z NAM WAS MUCH MORE ROBUST IN BRINGING IN THE STRATUS AND FOG. NAM HAS BEEN SHOWING THIS FOR A FEW DAYS PLUS THOSE SOUTH WINDS WILL BE BLOWING ACROSS A SNOW FIELD. SO EXPANDED THE PATCHY FOG THAT WAS IN THERE. FRIDAY/FRIDAY NIGHT...STRATUS AND FOG GET PUSHED EAST PRETTY FAST BY THE STRENGTHENING DOWNSLOPE WINDS. THERE MAY BE SOME HIGHER LEVEL CLOUD COVER AROUND. INCOMING SHORTWAVE TROUGH IN NORTHWEST FLOW ALOFT WILL PUSH A WEAK FRONT OR SURFACE TROUGH THROUGH LATER IN THE DAY BUT IT LOOKS LIKE WINDS WILL BE FROM A DOWNSLOPE DIRECTION. SO ENDED UP RAISING THE MAXES A LITTLE. LEFT FRONT QUADRANT OF JET WILL AFFECT THE NORTHERN PORTION OF THE AREA DURING THE NIGHT AS WELL AS THE ABOVE MENTIONED SHORTWAVE TROUGH...WHICH HAPPENS TO BE THE ONE TOPPING THE RIDGE RIGHT NOW NEAR WESTERN CANADA. ALL MODELS AGREE THAT THIS SYSTEM WILL HAVE A VERY STRONG PV ANOMALY AS WELL. MODELS DO NOT SHOW A LOT OF MOISTURE IN THE COLUMN BUT STRENGTH OF SYSTEM SHOULD COMPENSATE FOR THAT. SO EXPANDED THE SPRINKLES AND FLURRIES OVER A LARGER AREA AND THROUGH THE EVENING HOURS. SATURDAY/SATURDAY NIGHT...RIDGING AND DRYING ALOFT PUSH INTO THE AREA FOR SATURDAY. SO WILL HAVE PLENTY OF SUN ALONG WITH STRONG DOWNSLOPE WINDS. SO RAISED MAXES MORE AND I MAY NOT BE WARM ENOUGH AS I BELIEVE MODELS ARE TOO COOL. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 246 AM MST THU JAN 31 2013 MODEL AGREEMENT IS FAIRLY GOOD IN THE EXTENDED FORECAST. ALL SOLUTIONS ARE POINTING TO A TAME WEATHER PATTERN WITHOUT ANY BIG WEATHER CHANGES OR PRECIPITATION CHANCES. A SYSTEM WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES ON MONDAY...BRINGING ONLY A WIND SHIFT AND TEMPERATURES A DEGREE OR TWO COOLER. AFTER THAT...A RIDGE OF HIGH PRESSURE BUILDS BACK IN FROM THE WEST. TEMPERATURES SHOULD BE WELL ABOVE NORMAL FOR THIS TIME OF YEAR THROUGHOUT THE EXTENDED FORECAST. HIGHS SHOULD BE IN THE 50S FOR SUNDAY THROUGH TUESDAY...WITH HIGHS CLIMBING INTO THE 60S BY THE MIDDLE OF NEXT WEEK. GUIDANCE HAS PULLED BACK SOMEWHAT FOR HIGH TEMPERATURES ON SUNDAY BUT STILL THINK TEMPERATURES NEARING 60 FOR EASTERN COLORADO IS NOT OUT OF THE QUESTION. THE ONLY OTHER CONCERN FOR THE EXTENDED FORECAST WAS LOW TEMPERATURES. THE INITIALIZATION PROCEDURE INPUT LOW TEMPERATURES THAT WERE LIKELY TOO WARM. CONSIDERING THE ONGOING DROUGHT CONDITIONS AND MEX AND ECE GUIDANCE SUGGESTING TEMPERATURES MUCH LOWER THAN THE INITIALIZATION...HAVE LOWERED LOW TEMPERATURES A DEGREE OR TWO. GUIDANCE IS ALTERED BY CLIMATOLOGICAL DATA SO THIS COULD BE THE REASON MEX AND ECE GUIDANCE IS BEING HELD DOWN SOMEWHAT. HOWEVER...THE HIGHER LOW TEMPS SEEMED A LITTLE UNREASONABLE WITH CLEAR SKIES AND LIGHT WINDS THROUGHOUT THE EXTENDED PERIOD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 444 AM MST THU JAN 31 2013 AT THE BEGINNING OF THE PERIOD...EVEN THOUGH VFR CONDITIONS WILL EXIST...THE LOW AND MID LEVEL CLOUD DECK WILL BE QUITE THICK. SOME FLURRIES WITH LITTLE TO NO VISIBILITY RESTRICTIONS WILL OCCUR...MAINLY AT KGLD. BY LATE MORNING SOME CLEARING WILL OCCUR NEAR KGLD. THE WIND WILL BECOME BRIEFY GUSTY BEFORE DECREASING AND SHIFTING TO AN EASTERLY DIRECTION AS A BACKDOOR COLD FRONT PUSHES ACROSS THE AREA. DURING THE NIGHT THE LOW LEVELS WILL BECOME MORE MOIST AS SOUTH TO SOUTHEAST WINDS ADVECT THE MOISTURE IN. MVFR TO NEAR IFR CONDITIONS WILL OCCUR WHEN THIS BEGINS. THESE CONDITIONS WILL LAST LONGER AT KMCK THAN AT KGLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
533 AM CST THU JAN 31 2013 ...UPDATED FOR AVIATION... .SYNOPSIS... ISSUED AT 349 AM CST THU JAN 31 2013 THE 00Z UPPER AIR ANALYSES SHOWED ONE MAJOR SHORTWAVE TROUGH MOVING EASTWARD ACROSS ILLINOIS AND MISSOURI WHILE ANOTHER SHORTWAVE TROUGH WAS JUST UPSTREAM OVER NORTH DAKOTA PROGRESSING SOUTHEASTWARD. A LEAD ARCTIC FRONT WITH THE 1ST SHORTWAVE TROUGH HAD STALLED ACROSS WESTERN KANSAS AND SOUTHWESTERLY DOWNSLOPE WINDS WERE ACTUALLY PUSHING THE FRONT BACK TO THE NORTHEAST AS A WARM FRONT. IN FACT, TEMPERATURES AS OF 3 AM WERE IN THE LOWER 30S AT PLACES LIKE MCCOOK AND OGALLALA, NE AND GOODLAND, WHICH IS VERY BALMY FOR THIS TIME OF MORNING IN JANUARY. MID LEVEL CLOUD WAS PROGRESSING SOUTHWARD INTO NORTHWESTERN KANSAS. THE NEXT ARCTIC FRONT WAS SLOWLY EDGING SOUTHWARD INTO SOUTHERN SOUTH DAKOTA AND TEMPERATURES WERE WELL BELOW ZERO BEHIND THIS FRONT. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 349 AM CST THU JAN 31 2013 AS THE 2ND SHORTWAVE TROUGH MOVES SOUTHEAST TODAY, THE ASSOCIATED REINFORCING ARCTIC FRONT WILL PROGRESS SOUTHWARD INTO CENTRAL AND NORTHERN KANSAS LATE THIS MORNING, AND THEN SOUTHWESTWARD IN BACK DOOR FASHION INTO DODGE CITY AND PRATT BY THIS EVENING. THERE ARE SEVERAL COMPLICATING FACTORS FOR HIGH TEMPERATURES TODAY, INCLUDING PERSISTENCE OF SNOW COVER FROM GARDEN CITY TO DODGE CITY TO HAYS, DOWNSLOPE WARMING AHEAD OF THE FRONT, FRONTAL TIMING, AND THE AMOUNT OF MID LEVEL CLOUD COVER. TEMPERATURES WILL BE TRICKIEST AROUND HAYS AND STAFFORD WHERE IT IS NOT CLEAR IF THE ARCTIC AIR WILL ARRIVE BEFORE DAYTIME HEATING OCCURS. UPON COORDINATION, IT WAS DECIDED TO GO WITH MID 30S AT HAYS FOR AN EARLY HIGH AROUND 18-19Z, WITH FALLING TEMPERATURES THEREAFTER. WARMER 40S TO NEAR 50 DEGREES SEEMS REASONABLE FURTHER SOUTHWEST, WITH THE WARMEST READINGS IN PLACES WITH NO SNOW COVER INCLUDING SYRACUSE, LIBERAL AND MEDICINE LODGE. ALTHOUGH DODGE CITY, GARDEN CITY, JETMORE AND NESS CITY WILL BE IN THE WARM SECTOR ALL DAY, SNOW COVER WILL BE SLOW TO MELT, RESULTING IN HIGHS ONLY IN THE LOWER 40S BEFORE THE FRONT ARRIVES. HOWEVER, IF SNOW COVER IS MORE RAPID THAN EXPECTED, THEN HIGHS COULD REACH INTO THE MID 40S. BY TONIGHT, SURFACE LEE TROUGHING WILL DEVELOP AHEAD OF THE NEXT SHORTWAVE TROUGH APPROACHING THE NORTHERN ROCKIES AS THE MID LEVEL FLOW GAINS A SLIGHT DOWNSLOPE COMPONENT ACROSS THE CENTRAL ROCKIES. THIS WILL RESULT IN A RETURN TO SOUTH WINDS BY MIDNIGHT SO THAT TEMPERATURES MAY ACTUALLY REACH LOWS AROUND MIDNIGHT AND THEN HOLD STEADY OR SLOWLY RISE THEREAFTER. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 252 AM CST THU JAN 31 2013 LONG RANGE MODELS SHOW A TRANQUIL WEATHER PATTERN WITH DRY NORTHWEST UPPER LEVEL FLOW, A FEW MINOR UPPER LEVEL SHORTWAVE TROUGHS, AND WEAK CANADIAN COLD FRONTS. THE FIRST WAVE MOVES ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT WITH WINDS SHIFTING FROM SOUTH TO NORTH OVERNIGHT AND A WEAK COLD FRONT. THE NEXT UPPER LEVEL WAVE COMES ACROSS THE PLAINS FROM THE PACIFIC NORTHWEST ON SUNDAY NIGHT BUT THIS SYSTEM IS FAIRLY DRY. A STRONGER UPPER LEVEL SHORTWAVE TROUGH MOVES ACROSS THE NORTHERN PLAINS ON TUESDAY MORNING WITH THE MAIN UPPER JET STAYING WELL NORTH OF THE CENTRAL PLAINS. THE COLD AIR ASSOCIATED WITH THIS WAVE STAYS INTO THE UPPER MIDWEST. AFTER THE WAVE MOVES EAST INTO TUESDAY AND WEDNESDAY A WARMER AIRMASS MOVES INTO THE WESTERN HIGH PLAINS. OVERNIGHT LOWS ARE EXPECTED TO WARM FROM THE MID 20S FRIDAY NIGHT AND SATURDAY NIGHT TO THE 30S INTO WEDNESDAY NIGHT. DAYTIME HIGHS WARM FROM AROUND 50 ON FRIDAY TO THE MID AND UPPER 50S INTO WEDNESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 523 AM CST THU JAN 31 2013 A BACKDOOR ARCTIC COLD FRONT IS FORECAST TO MOVE SOUTHWESTWARD AND INTO WESTERN KANSAS THIS AFTERNOON WITH SOME LOW STRATUS DEVELOPING. AHEAD OF THE FRONT EXPECT MID LEVEL CLOUDINESS. SOUTHWEST TO NORTHWEST WINDS BECOME NORTHEAST TO EASTERLY WITH THE ARCTIC BOUNDARY WITH IFR CONDITIONS DEVELOPING. THE ARCTIC FRONT MAY COME A BIT FASTER THAN HRRR AND THE RAP MODELS FORECAST. FOR NOW WILL HAVE THE ARCTIC FRONT MOVING THROUGH KHYS BY AROUND 19Z, KDDC BY 23Z, AND KGCK BY 02Z. STRATUS MAY THEN ERODE IN THE KHYS AREA AFTER 03Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 40 17 49 24 / 0 0 0 0 GCK 43 18 51 24 / 0 0 0 0 EHA 51 22 55 25 / 0 0 0 0 LBL 50 21 53 24 / 0 0 0 0 HYS 34 12 44 22 / 0 0 0 0 P28 47 15 46 26 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FINCH SHORT TERM...FINCH LONG TERM...KRUSE AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
412 AM MST THU JAN 31 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 412 AM MST THU JAN 31 2013 FORECAST PROBLEMS WILL PROBLEMATIC TEMPERATURE FORECAST INTO TONIGHT AND HOW MUCH TO WARM UP THE HIGH TEMPERATURES INTO SATURDAY. SATELLITE SHOWING A BROAD UPPER TROUGH OVER THE TROUGH OVER THE WESTERN AND CENTRAL PACIFIC WITH A RIDGE ALONG THE WEST COAST OF NORTH AMERICA. A COUPLE OF SYSTEMS COMING INTO THE RIDGE ARE BEATING IT DOWN. A STRONG AND COLD SYSTEM IS DIGGING INTO THE NORTH CENTRAL PORTION OF THE COUNTRY. VERY COLD AIR MASS HAS MOVED FURTHER SOUTH FROM YESTERDAY AND IS NOT TOO FAR NORTH AND EAST OF OUR AREA. MODELS INITIALIZED WELL AT JET LEVEL WITH THE CANADIAN...GFS...AND NAM DOING THE BEST. MODELS INITIALIZED WELL AT MID LEVELS WITH THE GFS...CANADIAN...AND NAM DOING SLIGHTLY BETTER. LARGER SCALE MODELS DO NOT HAVE THE BACKDOOR COLD FRONT FAR ENOUGH SOUTH AND WEST BY 06Z...OH SURPRISE. THE RUC HAS CONTINUED TO GET BETTER AS THE NIGHT HAS PROGRESSED. OUTSIDE OF THE RUC ON THE LOW LEVEL THERMAL FIELD...THE ECMWF AND GFS WERE DOING A LITTLE BETTER THAN THE UKMET AND NAM. TODAY/TONIGHT...VERY THICK CLOUD COVER HAS SPREAD OVER THE AREA THROUGH THE NIGHT. WHAT THIS HAS DONE HAS PREVENTED ANY FALL OF THE TEMPERATURES AND IN FACT HAS CAUSED THE TEMPERATURES TO RISE SOME. NWP OUTPUT MUST BE UNDERDOING THIS CLOUD COVER AND IS TOO COOL WITH TEMPERATURES. THIS CLOUD COVER IS BEING CAUSED BY STRONG MID TO UPPER LEVEL JET. SOUNDINGS AND PLAN VIEW RELATIVE HUMIDITY PLOTS SHOW THIS CLOUD COVER LASTING MOST OF THE DAY...ESPECIALLY IN THE NORTHEAST PORTION. BACKDOOR COLD FRONT WITH VERY COLD AIR BEHIND IT HAS BEEN MOVING STEADILY TOWARD THE AREA THROUGH THE NIGHT AND IS NOT THAT FAR AWAY. RUC IS CATCHING ONTO THIS AT THIS TIME. INITIALLY WAS GOING TO CUT HIGH TEMPERATURES FROM GOING FORECAST BUT CLOUD COVER HAS COMPLICATED THAT. SO WILL BE STARTING MUCH WARMER THAN WHAT MOST OF THE MODELS SAY. FRONT SAGS ACROSS THE AREA THROUGH THE DAY WITH SOME LOCATIONS IN THE NORTHEAST HALF TO TWO THIRDS REACHING THEIR MAX BY 18Z. SO COMBINING REALITY AND THE RUC ADJUSTED MAX TEMPERATURES UP BUT HAVE EXTREMELY LOW CONFIDENCE ABOUT THIS. DID NOT GOES AS WARM AS IT BECAUSE OF THE CLOUD COVER. HRRR WOULD INDICATE HIGH TEMPERATURES ABOUT 10 DEGREES WARMER IN THE SOUTHWEST PORTION OF THE AREA THAT WHAT I HAVE. LEFT FRONT QUADRANT OF INCOMING JET WILL CONTINUE TO AFFECT THE NORTHEAST HALF TO TWO THIRDS OF THE AREA INTO EARLY AFTERNOON. SEVERAL STATIONS HAVE REPORTED BRIEF PERIODS OF FLURRIES. ALL MODEL OUTPUT AGREES IN PLACING LIGHT QPF IN THE ABOVE MENTIONED AREA. SREF PROBABILITIES AGREE WITH THAT. IT MAKES SENSE WITH THE JET... MESOSCALE FORCING AND LAPSE RATES IN PLACE. HOWEVER...DRIER AIR IN THE LOWEST LAYERS. SO INTRODUCED SCATTERED FLURRIES THROUGH MIDDAY WHEN THE FORCING AND MOISTURE LEAVE. PROBLEMATIC MIN FORECAST AS WELL. WINDS SHIFT AROUND TO A SOUTH DIRECTION PRETTY QUICKLY. NAM IS THE MOST AGGRESSIVE BUT IS SUPPORTED BY OTHER MODEL OUTPUT IN BRINGING STRATUS AND FOG DURING THE LATE EVENING AND OVERNIGHT HOURS. THIS IS AS THE COLD FRONT RETREATS BACK AS A WARM FRONT AND ALL THE MODELS ARE VERY SIMILAR IN DOING IT. MINS WILL PROBABLY BE REACHED IN THE EVENING ESPECIALLY IN THE WEST AND POSSIBLY IN THE SOUTH AND A NON-DIURNAL CURVE WILL HAVE TO BE INTRODUCED. BELIEVE MODELS ARE TOO COOL AND WENT ABOVE THE GUIDANCE. 06Z NAM WAS MUCH MORE ROBUST IN BRINGING IN THE STRATUS AND FOG. NAM HAS BEEN SHOWING THIS FOR A FEW DAYS PLUS THOSE SOUTH WINDS WILL BE BLOWING ACROSS A SNOW FIELD. SO EXPANDED THE PATCHY FOG THAT WAS IN THERE. FRIDAY/FRIDAY NIGHT...STRATUS AND FOG GET PUSHED EAST PRETTY FAST BY THE STRENGTHENING DOWNSLOPE WINDS. THERE MAY BE SOME HIGHER LEVEL CLOUD COVER AROUND. INCOMING SHORTWAVE TROUGH IN NORTHWEST FLOW ALOFT WILL PUSH A WEAK FRONT OR SURFACE TROUGH THROUGH LATER IN THE DAY BUT IT LOOKS LIKE WINDS WILL BE FROM A DOWNSLOPE DIRECTION. SO ENDED UP RAISING THE MAXES A LITTLE. LEFT FRONT QUADRANT OF JET WILL AFFECT THE NORTHERN PORTION OF THE AREA DURING THE NIGHT AS WELL AS THE ABOVE MENTIONED SHORTWAVE TROUGH...WHICH HAPPENS TO BE THE ONE TOPPING THE RIDGE RIGHT NOW NEAR WESTERN CANADA. ALL MODELS AGREE THAT THIS SYSTEM WILL HAVE A VERY STRONG PV ANOMALY AS WELL. MODELS DO NOT SHOW A LOT OF MOISTURE IN THE COLUMN BUT STRENGTH OF SYSTEM SHOULD COMPENSATE FOR THAT. SO EXPANDED THE SPRINKLES AND FLURRIES OVER A LARGER AREA AND THROUGH THE EVENING HOURS. SATURDAY/SATURDAY NIGHT...RIDGING AND DRYING ALOFT PUSH INTO THE AREA FOR SATURDAY. SO WILL HAVE PLENTY OF SUN ALONG WITH STRONG DOWNSLOPE WINDS. SO RAISED MAXES MORE AND I MAY NOT BE WARM ENOUGH AS I BELIEVE MODELS ARE TOO COOL. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 246 AM MST THU JAN 31 2013 MODEL AGREEMENT IS FAIRLY GOOD IN THE EXTENDED FORECAST. ALL SOLUTIONS ARE POINTING TO A TAME WEATHER PATTERN WITHOUT ANY BIG WEATHER CHANGES OR PRECIPITATION CHANCES. A SYSTEM WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES ON MONDAY...BRINGING ONLY A WIND SHIFT AND TEMPERATURES A DEGREE OR TWO COOLER. AFTER THAT...A RIDGE OF HIGH PRESSURE BUILDS BACK IN FROM THE WEST. TEMPERATURES SHOULD BE WELL ABOVE NORMAL FOR THIS TIME OF YEAR THROUGHOUT THE EXTENDED FORECAST. HIGHS SHOULD BE IN THE 50S FOR SUNDAY THROUGH TUESDAY...WITH HIGHS CLIMBING INTO THE 60S BY THE MIDDLE OF NEXT WEEK. GUIDANCE HAS PULLED BACK SOMEWHAT FOR HIGH TEMPERATURES ON SUNDAY BUT STILL THINK TEMPERATURES NEARING 60 FOR EASTERN COLORADO IS NOT OUT OF THE QUESTION. THE ONLY OTHER CONCERN FOR THE EXTENDED FORECAST WAS LOW TEMPERATURES. THE INITIALIZATION PROCEDURE INPUT LOW TEMPERATURES THAT WERE LIKELY TOO WARM. CONSIDERING THE ONGOING DROUGHT CONDITIONS AND MEX AND ECE GUIDANCE SUGGESTING TEMPERATURES MUCH LOWER THAN THE INITIALIZATION...HAVE LOWERED LOW TEMPERATURES A DEGREE OR TWO. GUIDANCE IS ALTERED BY CLIMATOLOGICAL DATA SO THIS COULD BE THE REASON MEX AND ECE GUIDANCE IS BEING HELD DOWN SOMEWHAT. HOWEVER...THE HIGHER LOW TEMPS SEEMED A LITTLE UNREASONABLE WITH CLEAR SKIES AND LIGHT WINDS THROUGHOUT THE EXTENDED PERIOD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1048 PM MST WED JAN 30 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. LIGHT WESTERLY WINDS WILL TURN NORTHWEST AND BECOME GUSTY AFTER 16Z...BECOMING LIGHT AGAIN FOLLOWING SUNSET AFTER 00Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...RRH AVIATION...JSL
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1023 AM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 10 AM UPDATE... OUR CURRENT FCST IS IN EXCELLENT SHAPE ATTM...SO ONLY COSMETIC CHGS WERE MADE. AS STG CAA CONTS TO FILTER ACRS THE FA LATE THIS MRNG...LES BANDS ARE TRYING TO ORGANIZE OFF BOTH LKS ERIE AND ONT. AS JUDGED FROM THE 12Z RAOBS AT BUF/DTX...THE MIXED LYR EXTENDS UP TO ABT 750 MB...WITH A FAIR MOISTURE SUPPLY UNDERNEATH THE BASE OF THE INVERSION. GIVEN CONTD CYCLONIC FLOW...FURTHER COOLING WITH TIME...AND IF ANYTHING...A DEEPENING OF THE SYNOPTIC MOISTURE THIS AFTN AND EVE...THERE`S NO REASON NOT TO EXPECT THE DVLPMT OF FAIRLY STG LAKE-EFFECT PLUMES OFF BOTH LKS. IN-HOUSE CAPE/SHEAR NOMOGRAM SHOWS ENUF OVER-LAND INSTAB THROUGH THIS EVE (00-03Z)...SO THAT THE BANDS MAY TAKE ON SOMEWHAT OF A CELLULAR APPEARANCE...AT TIMES. HOWEVER...ORGANIZATION IS NOT LIKELY TO BE SERIOUSLY COMPROMISED. ALSO...THE CSTAR-DERIVED INLAND EXTENT APPLICATION DEPICTS A FAIRLY DEEP INLAND PENETRATION THROUGHOUT THE EVE HRS...AT LEAST...WITH A GOOD UPSTREAM CONNECTION TO HURON/NRN LK MI/SUPERIOR...AND ALSO STG 0-1 KM SPEED SHEAR. THIS ALSO SEEMS WELL SUPPORTED BY SIM REFLECTIVITY PRESENTATIONS FROM THE NAM12...LOCAL ARW...AND HRRR MODELS. BOTTOM LN...THINGS APPEAR WELL ON TRACK FOR THE LES WRNG IN NRN ONEIDA...WITH A PD OF VERY HVY SNOW ANTICIPATED...FROM ROUGHLY 22-06Z. GIVEN DEEP MOISTURE...AND EXCELLENT CRYSTAL GROWTH PARAMETERS...2-3"/HR RATES ARE NOT OUT OF THE QUESTION. ELSEWHERE (ONONDAGA/MADISON/SRN ONEIDA)...DESPITE SOME ANTICIPATED WEAKENING LTR TNT...AS THE BAND DROPS SWD...THERE MAY BE ENUF RESIDUAL INTENSITY FOR ADVSY-LVL ACCUMS. WE`LL RE-VISIT THIS SITN EARLY THIS AFTN. ACRS THE TWIN TIERS...SOME CONVECTIVE SHSN ARE LIKELY TO FORM BY MID TO LATE AFTN...AIDED A BIT BY ADVECTION OF MOISTURE FROM LKS ERIE AND SRN MI IN STG WRLY FLOW. OVERALL...THOUGH...THE NATURE OF THEM WILL REMAIN SCTD. AS FOR THE WINDS...THEY`RE LIKELY TO BE AT THEIR PEAK THROUGH ABT 18Z...WITH A SLOW DIMINISHING TREND THEREAFTER...AS JUDGED FROM ISALLOBARIC AND MOMENTUM TRANSFER PROGS. A STEADY OR SLOWLY FALLING TEMP TREND IS WELL HANDLED IN THE GRIDS...SO ONLY VERY MINOR TWEAKS WERE NEEDED. PREV DISC... 620 AM...WILL DROP THE FLOOD WATCH FOR ERN ZONES AS STEADY RAIN IS MOVG OUT. OTRW JUST MINOR NEAR TERM TWEEKS WITH NO SIG CHGS TO FCST. PREV BLO... 450 AM...DROPPED FLOOD WATCH FOR THE CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACK EDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACK EDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAINLY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF THE BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAY SHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... 12Z UPDATE... STRONG COLD FRONT IS JUST FINISHING ITS BLAST THROUGH THE AREA...TAKING THE STEADIER RAIN SHOWERS WITH IT. WINDS WILL HAVE A MUCH EASIER TIME MIXING DOWN IN THE COLD AIR BEHIND THE FRONT...ALLOWING WESTERLY GUSTS FREQUENTLY IN THE 30-40 KT RANGE. GUSTS AT KSYR AND PERHAPS KRME WILL EVEN TOP OUT AROUND 35-45 KTS AT TIMES TODAY. EXPECTING SCT-BKN CLOUD DECK WITH SCT -SHSN AND MVFR CIG FOR SOME TERMINALS. THOUGH GENERALLY VFR TO MVFR IN TAFS TODAY WITH THE SNOW FLURRIES...SOME TERMINALS WILL HAVE TO WATCH FOR BRIEF SURPRISE IFR VIS FROM A HEAVIER LAKE EFFECT SNOW SHOWER. THE MAIN LAKE ONTARIO SNOW BAND WILL AT FIRST DEVELOP NORTH OF THE AREA THIS AFTERNOON...BUT SHOULD EDGE SOUTH ENOUGH TO INVOLVE KRME IN OCCASIONAL IFR VIS AFTER 03Z...AND BY 09Z ONWARD FOR KSYR. .OUTLOOK... FRI THRU SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS... NEAR TERM...MLJ SHORT TERM... LONG TERM...MDP/TAC AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
651 AM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 620 AM...WILL DROP THE FLOOD WATCH FOR ERN ZONES AS STEADY RAIN IS MOVG OUT. OTRW JUST MINOR NEAR TERM TWEEKS WITH NO SIG CHGS TO FCST. PREV BLO... 450 AM...DROPPED FLOOD WATCH FOR THER CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACKEDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACKEDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAILY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF TEH BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAYSHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... 12Z UPDATE... STRONG COLD FRONT IS JUST FINISHING ITS BLAST THROUGH THE AREA...TAKING THE STEADIER RAIN SHOWERS WITH IT. WINDS WILL HAVE A MUCH EASIER TIME MIXING DOWN IN THE COLD AIR BEHIND THE FRONT...ALLOWING WESTERLY GUSTS FREQUENTLY IN THE 30-40 KT RANGE. GUSTS AT KSYR AND PERHAPS KRME WILL EVEN TOP OUT AROUND 35-45 KTS AT TIMES TODAY. EXPECTING SCT-BKN CLOUD DECK WITH SCT -SHSN AND MVFR CIG FOR SOME TERMINALS. THOUGH GENERALLY VFR TO MVFR IN TAFS TODAY WITH THE SNOW FLURRIES...SOME TERMINALS WILL HAVE TO WATCH FOR BRIEF SURPRISE IFR VIS FROM A HEAVIER LAKE EFFECT SNOW SHOWER. THE MAIN LAKE ONTARIO SNOW BAND WILL AT FIRST DEVELOP NORTH OF THE AREA THIS AFTERNOON...BUT SHOULD EDGE SOUTH ENOUGH TO INVOLVE KRME IN OCCASIONAL IFR VIS AFTER 03Z...AND BY 09Z ONWARD FOR KSYR. .OUTLOOK... FRI THRU SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM...MDP/TAC AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
620 AM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 620 AM...WILL DROP THE FLOOD WATCH FOR ERN ZONES AS STEADY RAIN IS MOVG OUT. OTRW JUST MINOR NEAR TERM TWEEKS WITH NO SIG CHGS TO FCST. PREV BLO... 450 AM...DROPPED FLOOD WATCH FOR THER CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACKEDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACKEDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAILY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF TEH BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAYSHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /11Z THURSDAY THROUGH MONDAY/... 06Z UPDATE... STRONG WET SYSTEM IS PROGRESSING THROUGH THE REGION. SSE WIND AHEAD OF THE FRONT...WITH STRONG SSW FLOW NOT FAR OFF THE SURFACE. FOR KRME AND KAVP...LIKELY MEETING LLWS THRESHOLD AND THUS INCLUDED INITIALLY IN TAFS. HOWEVER...SURFACE WIND WILL ABRUPTLY SHIFT TO SW WITH BRIEF HEAVY SHOWERS AS FRONT PASSES...WITH TIMING AS INDICATED IN TAFS. THOUGH IFR NOT OUT OF QUESTION WITH FRONT...MAINLY MVFR IS ANTICIPATED AND HAS OCCURRED UPSTREAM. BEHIND FRONT...WINDS WILL HAVE A MUCH EASIER TIME MIXING DOWN...MITIGATING ANY FURTHER LLWS BUT ALSO ALLOWING GUSTS FREQUENTLY IN THE 30-40 KT RANGE. KSYR-KRME COULD EVEN GET A BIT HIGHER THAN THAT THIS AFTERNOON. SCT-BKN CLOUD DECK DURING THE DAYTIME HOURS...EVENTUALLY WITH SCT -SHSN AND MVFR CIG FOR SOME TERMINALS. LAKE ONTARIO SNOW BAND WILL AT FIRST DEVELOP NORTH OF THE AREA THIS AFTERNOON...BUT SHOULD EDGE SOUTH ENOUGH TO INVOLVE KRME IN OCCASIONAL IFR VIS 00Z-06Z FRIDAY...AND NOT LONG AFTER THAT FOR KSYR. .OUTLOOK... LATE THU NGT THRU SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS 1 TO UP TO 2.5 INCHES WITH THE HEAVIEST RAIN AXIS FURTHER WEST ACROSS THE FINGER LAKES AND CHEMUNG BASINS OF NY. WILL HAVE TWO BATCHES WITH THE INITIAL BATCH ALREADY IN WRN PA AND WRN NY NOW. THIS FIRST BATCH MOVES QUICKLY THROUGH THIS AFTN. RAINFALL THIS AFTN UP TO HALF AN INCH. QUICK RESPONSE ON STREAMS BUT NO FLOODING INITIALLY. THE COLD FRONT WILL COME THROUGH LATE EVE AND EARLY MORNING WITH MORE HEAVY RAIN. ANOTHER QUICK INCH IN LESS THAN 6 HOURS WHICH WILL BE MOSTLY RUNOFF. STREAMS AND RIVERS WILL RESPOND QUICKLY. FLASH FLOODING POSSIBLE...FOLLOWED BY MINOR RIVER FLOODING. FLOOD WATCH CONTINUES FOR ENTIRE CWA STARTING AT 4 PM INTO THURSDAY MORNING. RIVER FLOOD WARNINGS JUST ISSUED FOR WEST BRANCH DELAWARE RIVER AT WALTON TIOUGHNIOGA RIVER AT CORTLAND CHENANGO RIVER AT SHERBURNE SUSQUEHANNA RIVER AT VESTAL SUSQUEHANNA RIVER AT WAVERLY/SAYRE SUSQUEHANNA RIVER AT TOWANDA SUSQUEHANNA RIVER AT MESHOPPEN SUSQUEHANNA RIVER NEAR WILKES-BARRE && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST FRIDAY FOR NYZ009. && $$ LONG TERM...MDP/TAC AVIATION...MDP HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
454 AM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 450 AM...DROPPED FLOOD WATCH FOR THER CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACKEDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACKEDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAILY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF TEH BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAYSHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... 06Z UPDATE... STRONG WET SYSTEM IS PROGRESSING THROUGH THE REGION. SSE WIND AHEAD OF THE FRONT...WITH STRONG SSW FLOW NOT FAR OFF THE SURFACE. FOR KRME AND KAVP...LIKELY MEETING LLWS THRESHOLD AND THUS INCLUDED INITIALLY IN TAFS. HOWEVER...SURFACE WIND WILL ABRUPTLY SHIFT TO SW WITH BRIEF HEAVY SHOWERS AS FRONT PASSES...WITH TIMING AS INDICATED IN TAFS. THOUGH IFR NOT OUT OF QUESTION WITH FRONT...MAINLY MVFR IS ANTICIPATED AND HAS OCCURRED UPSTREAM. BEHIND FRONT...WINDS WILL HAVE A MUCH EASIER TIME MIXING DOWN...MITIGATING ANY FURTHER LLWS BUT ALSO ALLOWING GUSTS FREQUENTLY IN THE 30-40 KT RANGE. KSYR-KRME COULD EVEN GET A BIT HIGHER THAN THAT THIS AFTERNOON. SCT-BKN CLOUD DECK DURING THE DAYTIME HOURS...EVENTUALLY WITH SCT -SHSN AND MVFR CIG FOR SOME TERMINALS. LAKE ONTARIO SNOW BAND WILL AT FIRST DEVELOP NORTH OF THE AREA THIS AFTERNOON...BUT SHOULD EDGE SOUTH ENOUGH TO INVOLVE KRME IN OCCASIONAL IFR VIS 00Z-06Z FRIDAY...AND NOT LONG AFTER THAT FOR KSYR. .OUTLOOK... LATE THU NGT THRU SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS 1 TO UP TO 2.5 INCHES WITH THE HEAVIEST RAIN AXIS FURTHER WEST ACROSS THE FINGER LAKES AND CHEMUNG BASINS OF NY. WILL HAVE TWO BATCHES WITH THE INITIAL BATCH ALREADY IN WRN PA AND WRN NY NOW. THIS FIRST BATCH MOVES QUICKLY THROUGH THIS AFTN. RAINFALL THIS AFTN UP TO HALF AN INCH. QUICK RESPONSE ON STREAMS BUT NO FLOODING INITIALLY. THE COLD FRONT WILL COME THROUGH LATE EVE AND EARLY MORNING WITH MORE HEAVY RAIN. ANOTHER QUICK INCH IN LESS THAN 6 HOURS WHICH WILL BE MOSTLY RUNOFF. STREAMS AND RIVERS WILL RESPOND QUICKLY. FLASH FLOODING POSSIBLE...FOLLOWED BY MINOR RIVER FLOODING. FLOOD WATCH CONTINUES FOR ENTIRE CWA STARTING AT 4 PM INTO THURSDAY MORNING. RIVER FLOOD WARNINGS JUST ISSUED FOR WEST BRANCH DELAWARE RIVER AT WALTON TIOUGHNIOGA RIVER AT CORTLAND CHENANGO RIVER AT SHERBURNE SUSQUEHANNA RIVER AT VESTAL SUSQUEHANNA RIVER AT WAVERLY/SAYRE SUSQUEHANNA RIVER AT TOWANDA SUSQUEHANNA RIVER AT MESHOPPEN SUSQUEHANNA RIVER NEAR WILKES-BARRE && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR PAZ039-040-043-044- 047-048-072. WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR NYZ009-018-036-037- 044>046-056-057-062. WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST FRIDAY FOR NYZ009. && $$ LONG TERM...MDP/TAC AVIATION...MDP HYDROLOGY...
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
937 AM EST THU JAN 31 2013 .SYNOPSIS... COOL HIGH PRESSURE WILL BUILD IN FROM THE WEST TODAY...WITH BELOW NORMAL TEMPERATURES EXPECTED. IT WILL BE BREEZY TODAY... ALTHOUGH WINDS WILL NOT BE AS STRONG AS LAST NIGHT. A SERIES OF DRY COLD FRONTS WILL MOVE ACROSS THE AREA. THE FIRST FRONT WILL CROSS THE AREA FRIDAY FOLLOWED BY ANOTHER ON SUNDAY AND YET ANOTHER ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM THURSDAY...THE SEASONS HAVE CHANGED YET AGAIN WITH YESTERDAY`S SPRING-LIKE WEATHER REPLACED BY A RETURN TO WINTER TODAY. COLD ADVECTION ON WESTERLY WINDS BEHIND LAST NIGHT`S STRONG COLD FRONT WILL ALMOST PERFECTLY BALANCE NEARLY FULL SUNSHINE TODAY AND TEMPERATURES WILL STRUGGLE JUST TO RISE A FEW DEGREES BY AFTERNOON...REACHING 53-56 DEGREES AREAWIDE. THE 12Z GSO SOUNDING WAS BEST SIMULATED BY THE 12Z NAM AND RUC MODELS...AND THESE ARE THE TWO MODELS I BLENDED FOR MY UPDATED FORECAST TODAY. DOWNWARD REVISIONS HAVE BEEN MADE TO DEWPOINT FORECASTS FOR THE AFTERNOON HOURS WITH LOWER 20S DEWPOINTS EXPECTED TO MIX DOWN FROM A RESERVOIR OF VERY DRY AIR ALOFT. PRECIPITABLE WATER VALUES TODAY SHOULD RANGE FROM 0.20 TO 0.25 INCHES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...SHORTWAVE ROUNDING BASE OF MID LEVEL TROUGH EARLY FRI HELPS DRIVE A REINFORCING SHOT OF COLD AIR INTO THE REGION. DRY COLD FRONT PUSHES OFFSHORE BY MIDDAY WITH A PERIOD OF BRIEF BUT STRONG COLD ADVECTION ENDING LATE FRI NIGHT. TEMP DROP WILL BE SIGNIFICANT WITH GUIDANCE SHOWING 850 TEMPS DECREASING BY AS MUCH AS 10C IN SOME PLACES IN UNDER 12 HOURS. DEEP WEST TO NORTHWEST FLOW FRI INTO FRI NIGHT HELPS KEEP SKIES CLEAR. PATTERN BECOMES LESS AMPLIFIED AND MORE PROGRESSIVE LATE FRI NIGHT...SHUTTING OFF COLD ADVECTION. MORE PROGRESSIVE EVOLUTION OF MID LEVEL PATTERN HELPS MOVE CENTER OF SURFACE RIDGE AXIS OVER THE REGION FOR SAT MORNING...ALLOWING FOR SOME RADIATIONAL COOLING. DO NOT ANTICIPATE EFFECT TO BE VERY STRONG BUT TYPICAL COLD SPOTS WILL FLIRT WITH TEENS FOR LOWS. HIGHS FRI WILL STRUGGLE TO REACH CLIMO WHILE LOWS WILL DROP INTO THE LOW TO MID 20S IN MOST AREAS SAT MORNING. SURFACE RIDGE AXIS SHIFTS OFFSHORE SAT WITH WEAK RETURN FLOW SETTING UP FOR THE END OF THE PERIOD. ALOFT ANOTHER SHORTWAVE HELPS AMPLIFY THE MID LEVEL PATTERN...RESULTING IN A SHORT PERIOD OF DEEP WEST-SOUTHWEST FLOW AHEAD OF ANOTHER COLD FRONT MOVING INTO THE REGION AS THE PERIOD ENDS. ANTICIPATE AN INCREASE IN MID AND UPPER LEVEL CLOUD ASSOCIATED WITH THIS WAVE BUT DURATION OF RETURN FLOW IS NOT ENOUGH TO BRING SIGNIFICANT MOISTURE BACK INTO THE REGION BEFORE THE FRONT PASSES. ALTHOUGH SOME GUIDANCE IS POINTING TO SOME LIGHT ISOLATED PRECIP EARLY SUN MORNING DO NOT THINK THIS WILL BE THE CASE. WILL MAINTAIN A POP FORECAST AROUND 10 SAT NIGHT. TEMPERATURES REMAIN BELOW CLIMO SAT BUT END UP MUCH CLOSER TO CLIMO SAT NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 3 AM THURSDAY...A RATHER REPETITIVE PATTERN FOR THE EXTENDED AS AREAS OF HIGH PRESSURE PUSH OFFSHORE AHEAD OF A SERIES OF WEAK COLD FRONTS. FIRST COLD FRONT WILL CROSS THE AREA VERY EARLY SUNDAY MORNING. LIMITED FORCING COMBINED WITH ONLY MARGINAL PWATS SUGGESTS FROPA WILL BE DRY...AND ONLY ACT TO REINFORCE THE COOL AIR. HOWEVER...ANY WEAK CAA REMAINS WELL DISPLACED BEHIND THE FRONT...SO SUNDAY WILL END UP BEING WARMER THAN SATURDAY...ALTHOUGH BOTH DAYS WILL BE AROUND TO SLIGHTLY BELOW CLIMO. ANOTHER LARGE BUT WEAK AREA OF HIGH PRESSURE BUILDS DOWN FROM THE NW LATE SUNDAY AND PERSISTS INTO TUESDAY WHILE SLOWLY DRIFTING ACROSS THE REGION. THIS CONTINUES THE COOL AND DRY WEATHER WITH NEAR TO SLIGHTLY-BELOW SEASONABLE TEMPS. THIS HIGH PRESSURE THEN DRIFTS OFFSHORE TUESDAY AHEAD OF ANOTHER COLD FRONT PROGGED TO CROSS THE AREA LATE IN THE DAY. GUIDANCE SHOWING CONSIDERABLE AMPLITUDE DIFFERENCES IN THE TROUGH DRIVING THIS FRONT WHICH WILL HAVE SIGNIFICANT IMPACT ON PRECIP POTENTIAL. FOR NOW WILL KEEP INHERITED SCHC/SILENT POP FOR D6 SINCE BENEFICIAL CHANGES CANNOT BE MADE AT THIS TIME. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD THOUGH AHEAD OF THE COLD FRONT...WITH TEMPS RETURNING TO BELOW CLIMO FOR WEDNESDAY AS ANOTHER AREA OF HIGH PRESSURE RIDGES DOWN FROM THE NW. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 12Z...SCATTERED TO BROKEN MVFR LEVEL CLOUDS TRAVERSING MAINLY THE KILM TERMINAL WILL SHIFT QUICKLY OFFSHORE 13-14Z. SCATTERED TO BROKEN VFR LEVEL LOW CLOUDS WILL LIKELY PERSIST AT LEAST THROUGH THE EARLY MORNING HOURS FROM KLBT/KILM NORTH. SIGNIFICANT DRYING OF THE AIRMASS SHOULD LEAD TO GENERALLY CLEAR SKIES AT ALL TERMINALS BY LATE MORNING. A TIGHT PRESSURE GRADIENT WILL PRODUCE WSW-W WINDS 15-25 KNOTS WITH ISOLATED GUSTS 30-35 KNOTS EARLY THIS MORNING. WIND SPEEDS WILL GRADUALLY EASE THROUGH THE DAY. WILL NOT INCLUDE WIND SHEAR IN TAFS THIS MORNING AS KLTX WIND PROFILE DATA AND SURFACE REPORTS SUGGESTS WIND SPEEDS ARE GRADUALLY INCREASING SFC-2K. VFR THIS EVENING AND OVERNIGHT WITH WSW WINDS 6-12 KNOTS. EXTENDED OUTLOOK...VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM THURSDAY...EARLIER BLOWOUT TIDE CONDITIONS HAVE ABATED. WATER LEVELS AS MEASURED AT THE OFFICIAL NOS (NATIONAL OCEAN SERVICE) TIDE GAUGES REACHED -1.92 FT MLLW AT WRIGHTSVILLE BEACH... AND -1.50 FT MLLW AT MYRTLE BEACH. FOR THE NEXT LOW TIDE JUST AFTER 4 PM...WESTERLY WINDS SHOULD BE DIMINISHING WITH LESS IMPACT ON COASTAL WATER LEVELS. OTHERWISE...WEST WINDS AROUND 30 KNOTS WITH FREQUENT GALE-FORCE GUSTS ARE STILL OCCURRING ACROSS THE AREA THIS MORNING. I WISH THE GALE WARNING WERE STILL UP AS GUSTS AT THE FRYING PAN SHOALS BUOY CONTINUE TO ECLIPSE 40 KNOTS...AND WITH 12 FOOT SEAS I AM FAIRLY CERTAIN SUSTAINED GALE-FORCE WINDS ARE OCCURRING BEYOND 15 MILES FROM SHORE. THESE VERY STRONG WINDS SHOULD BEGIN TO ABATE OVER THE NEXT 2 HOURS AS HIGH PRESSURE OVER SOUTHERN LOUISIANA NOSES TOWARD THE CAROLINAS AND OUR PRESSURE GRADIENT BEGINS TO WEAKEN. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...SMALL CRAFT ADVISORY CONTINUES INTO FRI BEFORE PASSAGE OF COLD FRONT AND DEVELOPMENT OF OFFSHORE FLOW PUSHES 6 FT SEAS BEYOND 20 NM. STRONG BUT BRIEF COLD ADVECTION DURING THE SECOND HALF OF FRI INTO FRI NIGHT MAY REQUIRE A PERIOD OF SCEC HEADLINES. HIGH PRESSURE BUILDS IN FROM THE WEST LATE FRI NIGHT THEN SHIFTS OVER THE WATERS DURING SAT. WEAKENING GRADIENT ALLOWS WIND SPEEDS TO DROP FROM A SOLID 20 KT FRI TO UNDER 10 KT BY SAT MORNING. RETURN FLOW STARTS TO DEVELOPING SAT AFTERNOON AS HIGH PRESSURE SLIDES EAST OF THE WATERS. GRADIENT BECOMES PINCHED AHEAD OF NEXT COLD FRONT...WITH SOUTHWEST WINDS INCREASING TO 15 KT AS THE PERIOD ENDS. SEAS SUBSIDE DURING FRI...DROPPING FROM 4 TO 7 FT AT THE START OF THE PERIOD TO 3 TO 4 FT FRI EVENING. SEAS FALL FURTHER...CLOSE TO 2 FT...EARLY SAT BEFORE STARTING TO BUILD BACK CLOSER TO 3 TO 4 FT LATE IN THE PERIOD AS SOUTHWEST WINDS INCREASE. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 3 AM THURSDAY...A COLD FRONT WILL CROSS THE WATERS SUNDAY... TURNING WINDS TO THE W/NW AT 10-15 KTS ON SUNDAY BEFORE SLOWLY EASING TO LIGHT AND VARIABLE AGAIN MONDAY AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. SEAS WILL BE PRIMARILY WIND-DRIVEN THROUGH THE PERIOD...INCREASING FOR A SHORT TIME SUNDAY UP TO 2-4 FT... THEN DECREASING TO 1 TO 2 FT MONDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST FRIDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...TRA SHORT TERM...III LONG TERM...JDW AVIATION...MRR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
650 AM EST THU JAN 31 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE STATE EARLY THIS MORNING.... FOLLOWED BY COLDER AND DRIER AIR TODAY. A WEAK AND MOSTLY DRY COLD FRONT SYSTEM WILL CROSS THE AREA EARLY FRIDAY WITH HIGH PRESSURE BUILDING BACK IN FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 600 AM THURSDAY... SQUALL LINE HAS PUSHES EAST OF THE CWA AND TO TORNADO WATCH WAS ALLOWED TO EXPIRE AT 2AM. WINDS IMMEDIATELY BEHIND THE LINE CONTINUE TO GUST TO 30-35KT...BUT DIE OFF WITH WESTWARD EXTENT AWAY FROM THE LINE. THE IS AN AREA OF STRONGER GUSTS OVER NORTHERN GA AND WESTERN SC...BUT HRRR WIND GUST FIELDS SUGGEST THESE WINDS WILL SHIFT EAST ACROSS SC. THUS...WE WILL ALLOW THE WIND ADVISORY TO EXPIRE AT 4AM. THE COLD FRONT...CURRENTLY EMERGING EAST OF THE MOUNTAINS..WILL PUSH EAST ACROSS THE CWA THIS MORNING AND IN TO THE COASTAL PLAIN BY 12Z. EXPECT WINDS WILL GUST PERIODICALLY TO AROUND 20KT WITH THE FRONT...THEN BECOME MORE CONSISTENT IN THE 20-25KT RANGE OUT OF THE WEST BEHIND THE FRONT TODAY. A FEW SHOWERS ARE POSSIBLE ALONG THE FRONT...MAINLY NORTH...AND DRYING ALOFT SHOULD LIMIT COVERAGE IN THE SOUTH. DESPITE CLEARING BEHIND THE FRONT...MODEST COLD ADVECTION WILL DOMINATE THE FIRST HALF OF THE DAY... KEEPING TEMPS FROM RISING MORE THAN 4-6 DEGREES ON MOST PLACES...RANGING FROM THE MID 40S NORTHWEST TO LOWER 50S SOUTHEAST. ANOTHER SHORTWAVE TROUGH DIGGING SOUTHEAST OUT OF CANADA WILL SWING ACROSS THE MID ATLANTIC STATES LATE TONIGHT. STRENGTHENING DPVA AND A BRIEF SHOT OF 60-80M HEIGHT FALLS FOCUSED ALONG THE NC/VA BORDER AND NORTHWARD...COMBINED WITH A BAND OF MID LEVEL MOISTURE CROSSING THE MOUNTAINS MAY BE SUFFICIENT TO CAUSE FLURRIES...MAINLY IN THE 09-12Z TIME FRAME. THE GFS HAS THE MOST ABUNDANT MOISTURE IN GENERAL...WITH MOISTURE REACHING TO -10C IN A BAND THAT SPANS THE ENTIRE CWA. HOWEVER...MOISTURE WITHIN THE ICE NUCLEATION ZONE IS ONLY PRESENT NORTH OF I-40 AND MOST PRONOUNCED NEAR THE NC/VA BORDER. THE LIMITED DURATION OF LIFT AND MOISTURE..AS WELL AS A RELATIVELY DRY BOUNDARY LAYER AND POTENTIAL FOR SUBLIMATION...WILL KEEP THIS TO A NO IMPACT EVENT. LOWS IN THE UPPER 20S TO LOWER 30S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 250 AM WEDNESDAY... FOR FRIDAY/FRIDAY NIGHT: THE RISK OF A QUICK FLURRY OR SPRINKLE IS LIKELY TO STRETCH PAST SUNRISE FRIDAY AS THE MID LEVEL SHORTWAVE TROUGH SHIFTS EASTWARD OFF THE MIDATLANTIC COAST AND THE REINFORCING CLIPPER COLD FRONT MOVES EAST OF CENTRAL NC. THE LOWEST 10 KFT LAYER DRIES OUT RAPIDLY BY MID MORNING WITH WINDS IN THIS LAYER VEERING TO NORTHWESTERLY AND STRONG DEEP SUBSIDENCE COMMENCING AS THE 160 KT UPPER JET CORE SHIFTS FURTHER EAST OFF THE VA/NC COAST. EXPECT GENERALLY CLEAR SKIES FROM LATE MORNING THROUGH THE DAY WITH A DRY AND HIGHLY STABLE COLUMN. THE LOW LEVEL THERMAL STRUCTURE MIXING UP TO ABOUT 800 MB SUPPORTS CHILLY HIGHS FROM 36 NORTH TO 46 NEAR THE SC BORDER. TEMPS SHOULD DROP OFF QUICKLY AFTER SUNSET FRIDAY EVENING THEN LEVEL OFF AS WE BEGIN TO SEE INCREASING HIGH AND MID CLOUDS OVERNIGHT... AS MID LEVEL DPVA AND HEIGHT FALLS ARRIVE AHEAD OF THE NEXT CLIPPER. BUT THESE CLOUDS SHOULD BE FAIRLY THIN AND GIVEN THE VERY COLD YUKON ORIGINS OF THIS INCOMING AIR MASS AND THE WINDS GOING NEARLY CALM AS THE SURFACE RIDGE AXIS SETTLES OVERHEAD... STILL ANTICIPATE ABNORMALLY COLD LOWS OF 18-24. FOR SATURDAY/SATURDAY NIGHT: THE NEXT CLIPPER FRONT WILL STRETCH FROM THE GREAT LAKES ACROSS MO SATURDAY MORNING... WITH AN ASSOCIATED WEAK WARM FRONT EXTENDING FROM IL TO SC. THE WARM FRONT WILL SWEEP NORTHEASTWARD THROUGH THE NC SATURDAY AFTERNOON AS THE SURFACE RIDGE PUSHES OFF THE COAST. CLOUD COVER WILL CONTINUE TO THICKEN AND LOWER WITH INCREASING MID LEVEL HEIGHT FALLS IN ADVANCE OF THE MID LEVEL SHORTWAVE TROUGH APPROACHING NC. DESPITE THE CLOUDS... THE ENSUING SOUTHWEST LOW LEVEL FLOW SHOULD ALLOW THICKNESSES AND TEMPS TO REBOUND TO JUST SLIGHTLY BELOW NORMAL... HIGHS OF 45-50. MODELS DEPICT A 35-40 KT LOW LEVEL SOUTHWESTERLY JET MOVING THROUGH THE REGION LATE SATURDAY AFTERNOON INTO THE EVENING... COINCIDENT WITH FORECAST SOUNDINGS SHOWING DEEPENING MOISTURE FROM 850 MB UP BEYOND 500 MB... AND AHEAD OF A MID LEVEL VORTICITY MAX AND SHORTWAVE TROUGH THAT WILL BE TAKING ON A NEGATIVE TILT AS IT PASSES THROUGH NC. THE SUBCLOUD LAYER SHOULD REMAIN FAIRLY DRY HOWEVER... SO MUCH OF WHAT FALLS IS LIKELY TO EVAPORATE/SUBLIMATE. GIVEN THAT THE WEB BULB PROFILE ON FORECAST SOUNDINGS SHOULD BE CLOSE TO FREEZING AT THE SURFACE DURING THIS TIME IN THE NORTHERN FORECAST AREA AND LIKELY JUST ABOVE FREEZING IN THE SOUTH... A COMBINATION OF LIGHT SPRINKLES OR FLURRIES STILL APPEARS REASONABLE. INTERESTING TO NOTE ARE THE GFS`S LAPSE RATES ALOFT WHICH REACH 7.0 C/KM 800-500 MB SATURDAY NIGHT... SUGGESTING THAT IF DYNAMIC FORCING FOR ASCENT IS STRONG ENOUGH TO AUGMENT INSTABILITY ALOFT... WE MAY SEE A LIGHTNING STRIKE OR TWO IF THE GFS`S STRONGER VORTICITY MAX IS CORRECT. AT ANY RATE... WILL LEAVE IN A LOW CHANCE POP AREAWIDE FOR LATE AFTERNOON WELL INTO THE NIGHT... BUT AGAIN EXPECT LITTLE MORE THAN TRACE TO A COUPLE OF HUNDREDTHS OF AN INCH OF LIQUID EQUIVALENT AS THE SURFACE AIR REMAINS DRY. SKIES SHOULD CLEAR OUT LATE SATURDAY NIGHT WITH NVA IN THE WAKE OF THE EXITING TROUGH. LOWS 30-35. -GIH && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 315 AM WEDNESDAY... FOR SUNDAY: ONE LAST SHOT OF POLAR STREAM ENERGY DIVES DOWN THE SW SIDE OF THE MEAN TROUGH... FROM THE GREAT LAKES THROUGH WV AND ACROSS DELMARVA WITH A SURFACE CLIPPER COLD FRONT NOT FAR BEHIND. IT APPEARS THAT THE MID LEVELS WILL HAVE DRIED OUT AND STABILIZED BY THIS TIME... AND MOISTURE IS UNIMPRESSIVE IN THE SURFACE-BASED MIXED LAYER AS WELL... SO WILL SHOWS SOME CLOUDS SWEEPING THROUGH THE AREA BUT WITH NO PRECIP CHANCES. THICKNESSES REMAIN SEASONABLE SO EXPECT HIGHS OF 49-55. FOR SUNDAY NIGHT THROUGH WEDNESDAY: THE COLD LONGWAVE TROUGH OVER EASTERN NOAM FINALLY RETREATS NORTHWARD AND WEAKENS WITH RISING HEIGHTS AND A FLATTENING FLOW OVER OUR REGION LASTING THROUGH MID WEEK... AS MODIFYING SURFACE HIGH PRESSURE BUILDS IN. THE HIGH IS INITIALLY CHILLY AND TEMPS MONDAY SHOULD RUN SEVERAL DEGREES BELOW NORMAL... PARTICULARLY WITH MILKY SUNSHINE TO LIMIT INSOLATION AS ONE LAST MINOR WAVE AND MID LEVEL SPEED MAX MOVE IN FROM THE WEST. TEMPS SHOULD THEN RECOVER TO ABOVE NORMAL TUESDAY INTO WEDNESDAY AS THE SURFACE HIGH QUICKLY MODIFIES AS IT EASES TO OUR SOUTH. THE GFS/ECMWF BOTH SHOWS THIS HIGH PUSHING SOUTHWARD AND WEAKENING AS A BACKDOOR FRONT APPROACHES FROM THE NORTH... ALTHOUGH THE ECMWF SWINGS A POTENT NORTHERN STREAM WAVE THROUGH THE MIDATLANTIC REGION... AND AS A RESULT HAS A MUCH STRONGER AND FASTER BACKDOOR FRONT AND A NOTABLE COOLDOWN BY WEDNESDAY. WILL STAY WITH THE LESS AMPLIFIED ROUTE OF THE GFS AT THIS TIME... AND KEEP TEMPS MILD ON WEDNESDAY WITH FAIR SKIES. -GIH && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 650 AM THURSDAY... COLD CURRENTLY PUSHING EAST THROUGH THE AREA WILL FORCE THE REMAINING SHOWERS AND 3-4K FT CEILINGS BETWEEN KRWI AND KFAY TO MOVE EAST OF THE AREA. THE STRONGEST WESTERLY WINDS ARE CURRENTLY OVER THE SOUTHERN PORTIONS OF THE AREA...WHERE 25-30KT GUSTS ARE STILL BEING REPORTED. THESE WINDS WILL WEAKEN THIS MORNING ONCE THE FRONT MOVES THROUGH THE AREA. HOWEVER...THE APPROACH OF ANOTHER DISTURBANCE FROM THE NORTHWEST AND STRENGTHENING LOW LEVEL WINDS WILL LEAD TO 15-20KT SUSTAINED WESTERLY WINDS WITH GUSTS APPROACHING 30KT POSSIBLE LATER THIS AFTERNOON. WHILE VFR CEILINGS AND VSBYS WILL PREVAIL...A CROSSWIND MAY CAUSE SOME ADVERSE AVIATION CONDITIONS FOR SMALLER AIRCRAFT. LOSS OF HEATING SHOULD ALLOW WINDS TO WEAKEN AFTER 00Z..THOUGH SPORADIC GUSTS TO AROUND 20KT MAY CONTINUE INTO THE OVERNIGHT HOURS. MID CLOUDS WILL INCREASE LATE TONIGHT AS THE AFOREMENTIONED DISTURBANCE NEARS THE AREA. OUTLOOK...VFR CONDITIONS ARE GENERALLY EXPECTED TO PREVAIL THROUGH EARLY NEXT WEEK. A DISTURBANCE FORECAST TO CROSS THE AREA SATURDAY/SATURDAY NIGHT WILL BRING ADDED CLOUD COVER AND THE POTENTIAL FOR A SHORT PERIOD OF RAIN OR SNOW. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
325 AM EST THU JAN 31 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE STATE EARLY THIS MORNING.... FOLLOWED BY COLDER AND DRIER AIR TODAY. A WEAK AND MOSTLY DRY COLD FRONT SYSTEM WILL CROSS THE AREA EARLY FRIDAY WITH HIGH PRESSURE BUILDING BACK IN FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 AM THURSDAY... A WIND ADVISORY REMAINS IN EFFECT ACROSS ALL OF CENTRAL NC THROUGH 4 AM LST. SQUALL LINE HAS PUSHES EAST OF THE CWA AND TO TORNADO WATCH WAS ALLOWED TO EXPIRE AT 2AM. WINDS IMMEDIATELY BEHIND THE LINE CONTINUE TO GUST TO 30-35KT...BUT DIE OFF WITH WESTWARD EXTENT AWAY FROM THE LINE. THE IS AN AREA OF STRONGER GUSTS OVER NORTHERN GA AND WESTERN SC...BUT HRRR WIND GUST FIELDS SUGGEST THESE WINDS WILL SHIFT EAST ACROSS SC. THUS...WE WILL ALLOW THE WIND ADVISORY TO EXPIRE AT 4AM. THE COLD FRONT...CURRENTLY EMERGING EAST OF THE MOUNTAINS..WILL PUSH EAST ACROSS THE CWA THIS MORNING AND IN TO THE COASTAL PLAIN BY 12Z. EXPECT WINDS WILL GUST PERIODICALLY TO AROUND 20KT WITH THE FRONT...THEN BECOME MORE CONSISTENT IN THE 20-25KT RANGE OUT OF THE WEST BEHIND THE FRONT TODAY. A FEW SHOWERS ARE POSSIBLE ALONG THE FRONT...MAINLY NORTH...AND DRYING ALOFT SHOULD LIMIT COVERAGE IN THE SOUTH. DESPITE CLEARING BEHIND THE FRONT...MODEST COLD ADVECTION WILL DOMINATE THE FIRST HALF OF THE DAY... KEEPING TEMPS FROM RISING MORE THAN 4-6 DEGREES ON MOST PLACES...RANGING FROM THE MID 40S NORTHWEST TO LOWER 50S SOUTHEAST. ANOTHER SHORTWAVE TROUGH DIGGING SOUTHEAST OUT OF CANADA WILL SWING ACROSS THE MID ATLANTIC STATES LATE TONIGHT. STRENGTHENING DPVA AND A BRIEF SHOT OF 60-80M HEIGHT FALLS FOCUSED ALONG THE NC/VA BORDER AND NORTHWARD...COMBINED WITH A BAND OF MID LEVEL MOISTURE CROSSING THE MOUNTAINS MAY BE SUFFICIENT TO CAUSE FLURRIES...MAINLY IN THE 09-12Z TIME FRAME. THE GFS HAS THE MOST ABUNDANT MOISTURE IN GENERAL...WITH MOISTURE REACHING TO -10C IN A BAND THAT SPANS THE ENTIRE CWA. HOWEVER...MOISTURE WITHIN THE ICE NUCLEATION ZONE IS ONLY PRESENT NORTH OF I-40 AND MOST PRONOUNCED NEAR THE NC/VA BORDER. THE LIMITED DURATION OF LIFT AND MOISTURE..AS WELL AS A RELATIVELY DRY BOUNDARY LAYER AND POTENTIAL FOR SUBLIMATION...WILL KEEP THIS TO A NO IMPACT EVENT. LOWS IN THE UPPER 20S TO LOWER 30S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 250 AM WEDNESDAY... FOR FRIDAY/FRIDAY NIGHT: THE RISK OF A QUICK FLURRY OR SPRINKLE IS LIKELY TO STRETCH PAST SUNRISE FRIDAY AS THE MID LEVEL SHORTWAVE TROUGH SHIFTS EASTWARD OFF THE MIDATLANTIC COAST AND THE REINFORCING CLIPPER COLD FRONT MOVES EAST OF CENTRAL NC. THE LOWEST 10 KFT LAYER DRIES OUT RAPIDLY BY MID MORNING WITH WINDS IN THIS LAYER VEERING TO NORTHWESTERLY AND STRONG DEEP SUBSIDENCE COMMENCING AS THE 160 KT UPPER JET CORE SHIFTS FURTHER EAST OFF THE VA/NC COAST. EXPECT GENERALLY CLEAR SKIES FROM LATE MORNING THROUGH THE DAY WITH A DRY AND HIGHLY STABLE COLUMN. THE LOW LEVEL THERMAL STRUCTURE MIXING UP TO ABOUT 800 MB SUPPORTS CHILLY HIGHS FROM 36 NORTH TO 46 NEAR THE SC BORDER. TEMPS SHOULD DROP OFF QUICKLY AFTER SUNSET FRIDAY EVENING THEN LEVEL OFF AS WE BEGIN TO SEE INCREASING HIGH AND MID CLOUDS OVERNIGHT... AS MID LEVEL DPVA AND HEIGHT FALLS ARRIVE AHEAD OF THE NEXT CLIPPER. BUT THESE CLOUDS SHOULD BE FAIRLY THIN AND GIVEN THE VERY COLD YUKON ORIGINS OF THIS INCOMING AIR MASS AND THE WINDS GOING NEARLY CALM AS THE SURFACE RIDGE AXIS SETTLES OVERHEAD... STILL ANTICIPATE ABNORMALLY COLD LOWS OF 18-24. FOR SATURDAY/SATURDAY NIGHT: THE NEXT CLIPPER FRONT WILL STRETCH FROM THE GREAT LAKES ACROSS MO SATURDAY MORNING... WITH AN ASSOCIATED WEAK WARM FRONT EXTENDING FROM IL TO SC. THE WARM FRONT WILL SWEEP NORTHEASTWARD THROUGH THE NC SATURDAY AFTERNOON AS THE SURFACE RIDGE PUSHES OFF THE COAST. CLOUD COVER WILL CONTINUE TO THICKEN AND LOWER WITH INCREASING MID LEVEL HEIGHT FALLS IN ADVANCE OF THE MID LEVEL SHORTWAVE TROUGH APPROACHING NC. DESPITE THE CLOUDS... THE ENSUING SOUTHWEST LOW LEVEL FLOW SHOULD ALLOW THICKNESSES AND TEMPS TO REBOUND TO JUST SLIGHTLY BELOW NORMAL... HIGHS OF 45-50. MODELS DEPICT A 35-40 KT LOW LEVEL SOUTHWESTERLY JET MOVING THROUGH THE REGION LATE SATURDAY AFTERNOON INTO THE EVENING... COINCIDENT WITH FORECAST SOUNDINGS SHOWING DEEPENING MOISTURE FROM 850 MB UP BEYOND 500 MB... AND AHEAD OF A MID LEVEL VORTICITY MAX AND SHORTWAVE TROUGH THAT WILL BE TAKING ON A NEGATIVE TILT AS IT PASSES THROUGH NC. THE SUBCLOUD LAYER SHOULD REMAIN FAIRLY DRY HOWEVER... SO MUCH OF WHAT FALLS IS LIKELY TO EVAPORATE/SUBLIMATE. GIVEN THAT THE WEB BULB PROFILE ON FORECAST SOUNDINGS SHOULD BE CLOSE TO FREEZING AT THE SURFACE DURING THIS TIME IN THE NORTHERN FORECAST AREA AND LIKELY JUST ABOVE FREEZING IN THE SOUTH... A COMBINATION OF LIGHT SPRINKLES OR FLURRIES STILL APPEARS REASONABLE. INTERESTING TO NOTE ARE THE GFS`S LAPSE RATES ALOFT WHICH REACH 7.0 C/KM 800-500 MB SATURDAY NIGHT... SUGGESTING THAT IF DYNAMIC FORCING FOR ASCENT IS STRONG ENOUGH TO AUGMENT INSTABILITY ALOFT... WE MAY SEE A LIGHTNING STRIKE OR TWO IF THE GFS`S STRONGER VORTICITY MAX IS CORRECT. AT ANY RATE... WILL LEAVE IN A LOW CHANCE POP AREAWIDE FOR LATE AFTERNOON WELL INTO THE NIGHT... BUT AGAIN EXPECT LITTLE MORE THAN TRACE TO A COUPLE OF HUNDREDTHS OF AN INCH OF LIQUID EQUIVALENT AS THE SURFACE AIR REMAINS DRY. SKIES SHOULD CLEAR OUT LATE SATURDAY NIGHT WITH NVA IN THE WAKE OF THE EXITING TROUGH. LOWS 30-35. -GIH && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 315 AM WEDNESDAY... FOR SUNDAY: ONE LAST SHOT OF POLAR STREAM ENERGY DIVES DOWN THE SW SIDE OF THE MEAN TROUGH... FROM THE GREAT LAKES THROUGH WV AND ACROSS DELMARVA WITH A SURFACE CLIPPER COLD FRONT NOT FAR BEHIND. IT APPEARS THAT THE MID LEVELS WILL HAVE DRIED OUT AND STABILIZED BY THIS TIME... AND MOISTURE IS UNIMPRESSIVE IN THE SURFACE-BASED MIXED LAYER AS WELL... SO WILL SHOWS SOME CLOUDS SWEEPING THROUGH THE AREA BUT WITH NO PRECIP CHANCES. THICKNESSES REMAIN SEASONABLE SO EXPECT HIGHS OF 49-55. FOR SUNDAY NIGHT THROUGH WEDNESDAY: THE COLD LONGWAVE TROUGH OVER EASTERN NOAM FINALLY RETREATS NORTHWARD AND WEAKENS WITH RISING HEIGHTS AND A FLATTENING FLOW OVER OUR REGION LASTING THROUGH MID WEEK... AS MODIFYING SURFACE HIGH PRESSURE BUILDS IN. THE HIGH IS INITIALLY CHILLY AND TEMPS MONDAY SHOULD RUN SEVERAL DEGREES BELOW NORMAL... PARTICULARLY WITH MILKY SUNSHINE TO LIMIT INSOLATION AS ONE LAST MINOR WAVE AND MID LEVEL SPEED MAX MOVE IN FROM THE WEST. TEMPS SHOULD THEN RECOVER TO ABOVE NORMAL TUESDAY INTO WEDNESDAY AS THE SURFACE HIGH QUICKLY MODIFIES AS IT EASES TO OUR SOUTH. THE GFS/ECMWF BOTH SHOWS THIS HIGH PUSHING SOUTHWARD AND WEAKENING AS A BACKDOOR FRONT APPROACHES FROM THE NORTH... ALTHOUGH THE ECMWF SWINGS A POTENT NORTHERN STREAM WAVE THROUGH THE MIDATLANTIC REGION... AND AS A RESULT HAS A MUCH STRONGER AND FASTER BACKDOOR FRONT AND A NOTABLE COOLDOWN BY WEDNESDAY. WILL STAY WITH THE LESS AMPLIFIED ROUTE OF THE GFS AT THIS TIME... AND KEEP TEMPS MILD ON WEDNESDAY WITH FAIR SKIES. -GIH && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 1250 AM THURSDAY... SQUALL LINE CURRENTLY EXTENDS FROM KAVC TO KJNX TO BETWEEN KFAY AND KCTZ...MOVING EAST AT AROUND 30 MPH. STRONGEST SOUTHERLY WINDS CONTINUE ALONG AND AHEAD OF THE LINE WHERE 35-40KT GUSTS ARE REPORTED. HEAVY RAIN AND A SHORT PERIOD OF IFR/LIFR VSBYS AND CEILINGS WILL OCCUR AT KRWI BETWEEN 06Z AND 07Z. BEHIND THE LINE...SOUTHWESTERLY WINDS WILL CONTINUE TO GUST TO 25-30KT IMMEDIATELY BEHIND THE LINE...WITH THE STRONGEST GUSTS LIKELY TO ACCOMPANY SCATTERED SHOWERS THROUGH 09Z. THE MAIN COLD FRONT IS CURRENTLY CROSSING THE MOUNTAINS AND WILL CROSS THE AREAS BY 12Z. WINDS WILL TURN TO MORE WESTERLY WITH THE FRONT AS CEILINGS AND VSBYS RETURN TO VFR. WHILE THERE MAY BE A WEAKENING TREND IN WINDS...EXPECT THERE WILL STILL BE SOME SPORADIC WIND GUSTS THROUGH THE MORNING HOURS...WITH WIDESPREAD WIND GUSTS TO 20-25KT OUT OF THE WEST DURING THE DAY. OUTLOOK...VFR CONDITIONS ARE THEN EXPECTED TO PREVAIL THROUGH EARLY NEXT WEEK. ALTHOUGH...A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE AREA...ONE FRIDAY MORNING AND ONE SATURDAY NIGHT AND COULD PRODUCE A PERIOD OF INCREASED CLOUDINESS...WITH EVEN A SMALL POSSIBILITY OF SOME SPRINKLES OR FLURRIES. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY THROUGH 4 AM EST THIS MORNING FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...CBL/SMITH NEAR TERM...SMITH SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...KRR/SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
308 AM EST THU JAN 31 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE STATE EARLY THIS MORNING....FOLLOWED BY COLDER AND DRIER AIR TODAY. A WEAK AND MOSTLY DRY COLD FRONT SYSTEM WILL CROSS THE AREA EARLY FRIDAY WITH HIGH PRESSURE BUILDING BACK IN FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 AM THURSDAY... ...A WIND ADVISORY ALSO REMAINS IN EFFECT ACROSS ALL OF CENTRAL NC THROUGH 4 AM LST... SQUALL LINE HAS PUSHES EAST OF THE CWA AND TO TORNADO WATCH WAS ALLOWED TO EXPIRE AT 2AM. WINDS IMMEDIATELY BEHIND THE LINE CONTINUE TO GUST TO 30-35KT...BUT DIE OFF WITH WESTWARD EXTENT AWAY FROM THE LINE. THE IS AN AREA OF STRONGER GUSTS OVER NORTHERN GA AND WESTERN SC...BUT HRRR WIND GUST FIELDS SUGGEST THESE WINDS WILL SHIFT EAST ACROSS SC. THUS...WE WILL ALLOW THE WIND ADVISORY TO EXPIRE AT 4AM. THE COLD FRONT...CURRENTLY EMERGING EAST OF THE MOUNTAINS..WILL PUSH EAST ACROSS THE CWA THIS MORNING AND IN TO THE COASTAL PLAIN BY 12Z. EXPECT WINDS WILL GUST PERIODICALLY TO AROUND 20KT WITH THE FRONT...THEN BECOME MORE CONSISTENT IN THE 20-25KT RANGE OUT OF THE WEST BEHIND THE FRONT TODAY. A FEW SHOWERS ARE POSSIBLE ALONG THE FRONT...MAINLY NORTH...AND DRYING ALOFT SHOULD LIMIT COVERAGE IN THE SOUTH. DESPITE CLEARING BEHIND THE FRONT...MODEST COLD ADVECTION WILL DOMINATE THE FIRST HALF OF THE DAY... KEEPING TEMPS FROM RISING MORE THAN 4-6 DEGREES ON MOST PLACES...RANGING FROM THE MID 40S NORTHWEST TO LOWER 50S SOUTHEAST. ANOTHER SHORTWAVE TROUGH DIGGING SOUTHEAST OUT OF CANADA WILL SWING ACROSS THE MID ATLANTIC STATES LATE TONIGHT. STRENGTHENING DPVA AND A BRIEF SHOT OF 60-80M HEIGHT FALLS FOCUSED ALONG THE NC/VA BORDER AND NORTHWARD...COMBINED WITH A BAND OF MID LEVEL MOISTURE CROSSING THE MOUNTAINS MAY BE SUFFICIENT TO CAUSE FLURRIES...MAINLY IN THE 09-12Z TIME FRAME. THE GFS HAS THE MOST ABUNDANT MOISTURE IN GENERAL...WITH MOISTURE REACHING TO -10C IN A BAND THAT SPANS THE ENTIRE CWA. HOWEVER...MOISTURE WITHIN THE ICE NUCLEATION ZONE IS ONLY PRESENT NORTH OF I-40 AND MOST PRONOUNCED NEAR THE NC/VA BORDER. THE LIMITED DURATION OF LIFT AND MOISTURE..AS WELL AS A RELATIVELY DRY BOUNDARY LAYER AND POTENTIAL FOR SUBLIMATION...WILL KEEP THIS TO A NO IMPACT EVENT. LOWS IN THE UPPER 20S TO LOWER 30S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 250 AM WEDNESDAY... FOR FRIDAY/FRIDAY NIGHT: THE RISK OF A QUICK FLURRY OR SPRINKLE IS LIKELY TO STRETCH PAST SUNRISE FRIDAY AS THE MID LEVEL SHORTWAVE TROUGH SHIFTS EASTWARD OFF THE MIDATLANTIC COAST AND THE REINFORCING CLIPPER COLD FRONT MOVES EAST OF CENTRAL NC. THE LOWEST 10 KFT LAYER DRIES OUT RAPIDLY BY MID MORNING WITH WINDS IN THIS LAYER VEERING TO NORTHWESTERLY AND STRONG DEEP SUBSIDENCE COMMENCING AS THE 160 KT UPPER JET CORE SHIFTS FURTHER EAST OFF THE VA/NC COAST. EXPECT GENERALLY CLEAR SKIES FROM LATE MORNING THROUGH THE DAY WITH A DRY AND HIGHLY STABLE COLUMN. THE LOW LEVEL THERMAL STRUCTURE MIXING UP TO ABOUT 800 MB SUPPORTS CHILLY HIGHS FROM 36 NORTH TO 46 NEAR THE SC BORDER. TEMPS SHOULD DROP OFF QUICKLY AFTER SUNSET FRIDAY EVENING THEN LEVEL OFF AS WE BEGIN TO SEE INCREASING HIGH AND MID CLOUDS OVERNIGHT... AS MID LEVEL DPVA AND HEIGHT FALLS ARRIVE AHEAD OF THE NEXT CLIPPER. BUT THESE CLOUDS SHOULD BE FAIRLY THIN AND GIVEN THE VERY COLD YUKON ORIGINS OF THIS INCOMING AIR MASS AND THE WINDS GOING NEARLY CALM AS THE SURFACE RIDGE AXIS SETTLES OVERHEAD... STILL ANTICIPATE ABNORMALLY COLD LOWS OF 18-24. FOR SATURDAY/SATURDAY NIGHT: THE NEXT CLIPPER FRONT WILL STRETCH FROM THE GREAT LAKES ACROSS MO SATURDAY MORNING... WITH AN ASSOCIATED WEAK WARM FRONT EXTENDING FROM IL TO SC. THE WARM FRONT WILL SWEEP NORTHEASTWARD THROUGH THE NC SATURDAY AFTERNOON AS THE SURFACE RIDGE PUSHES OFF THE COAST. CLOUD COVER WILL CONTINUE TO THICKEN AND LOWER WITH INCREASING MID LEVEL HEIGHT FALLS IN ADVANCE OF THE MID LEVEL SHORTWAVE TROUGH APPROACHING NC. DESPITE THE CLOUDS... THE ENSUING SOUTHWEST LOW LEVEL FLOW SHOULD ALLOW THICKNESSES AND TEMPS TO REBOUND TO JUST SLIGHTLY BELOW NORMAL... HIGHS OF 45-50. MODELS DEPICT A 35-40 KT LOW LEVEL SOUTHWESTERLY JET MOVING THROUGH THE REGION LATE SATURDAY AFTERNOON INTO THE EVENING... COINCIDENT WITH FORECAST SOUNDINGS SHOWING DEEPENING MOISTURE FROM 850 MB UP BEYOND 500 MB... AND AHEAD OF A MID LEVEL VORTICITY MAX AND SHORTWAVE TROUGH THAT WILL BE TAKING ON A NEGATIVE TILT AS IT PASSES THROUGH NC. THE SUBCLOUD LAYER SHOULD REMAIN FAIRLY DRY HOWEVER... SO MUCH OF WHAT FALLS IS LIKELY TO EVAPORATE/SUBLIMATE. GIVEN THAT THE WEB BULB PROFILE ON FORECAST SOUNDINGS SHOULD BE CLOSE TO FREEZING AT THE SURFACE DURING THIS TIME IN THE NORTHERN FORECAST AREA AND LIKELY JUST ABOVE FREEZING IN THE SOUTH... A COMBINATION OF LIGHT SPRINKLES OR FLURRIES STILL APPEARS REASONABLE. INTERESTING TO NOTE ARE THE GFS`S LAPSE RATES ALOFT WHICH REACH 7.0 C/KM 800-500 MB SATURDAY NIGHT... SUGGESTING THAT IF DYNAMIC FORCING FOR ASCENT IS STRONG ENOUGH TO AUGMENT INSTABILITY ALOFT... WE MAY SEE A LIGHTNING STRIKE OR TWO IF THE GFS`S STRONGER VORTICITY MAX IS CORRECT. AT ANY RATE... WILL LEAVE IN A LOW CHANCE POP AREAWIDE FOR LATE AFTERNOON WELL INTO THE NIGHT... BUT AGAIN EXPECT LITTLE MORE THAN TRACE TO A COUPLE OF HUNDREDTHS OF AN INCH OF LIQUID EQUIVALENT AS THE SURFACE AIR REMAINS DRY. SKIES SHOULD CLEAR OUT LATE SATURDAY NIGHT WITH NVA IN THE WAKE OF THE EXITING TROUGH. LOWS 30-35. -GIH && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 150 PM WEDNESDAY... THE WARMER START AND INCREASING SUN EXPECTED ON SUNDAY WILL ALLOW HIGHS TO REBOUND FURTHER...INTO THE SEASONABLE LOWER 50S OVER MOST OF THE AREA. THE EAST COAST TROF AXIS SHIFTS OFFSHORE AND UPPER FLOW WILL NOT BE AS AMPLIFIED EARLY NEXT WEEK. ANOTHER REINFORCING BACKDOOR COLD FRONT WILL BE SLOWLY EDGING SOUTH AND POTENTIALLY STALLING ACROSS THE MID ATLANTIC ON TUESDAY INTO WEDNESDAY...BUT MOISTURE WILL BE LACKING AND FORCING WILL BE UNFOCUSED IN THE WEAKER UPPER FLOW. AT THIS POINT THE WEATHER MONDAY THROUGH WEDNESDAY LOOKS DRY AND SEASONABLY MILD WITH HIGHS MOSTLY IN THE LOW TO MID 50S EACH DAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 1250 AM THURSDAY... SQUALL LINE CURRENTLY EXTENDS FROM KAVC TO KJNX TO BETWEEN KFAY AND KCTZ...MOVING EAST AT AROUND 30 MPH. STRONGEST SOUTHERLY WINDS CONTINUE ALONG AND AHEAD OF THE LINE WHERE 35-40KT GUSTS ARE REPORTED. HEAVY RAIN AND A SHORT PERIOD OF IFR/LIFR VSBYS AND CEILINGS WILL OCCUR AT KRWI BETWEEN 06Z AND 07Z. BEHIND THE LINE...SOUTHWESTERLY WINDS WILL CONTINUE TO GUST TO 25-30KT IMMEDIATELY BEHIND THE LINE...WITH THE STRONGEST GUSTS LIKELY TO ACCOMPANY SCATTERED SHOWERS THROUGH 09Z. THE MAIN COLD FRONT IS CURRENTLY CROSSING THE MOUNTAINS AND WILL CROSS THE AREAS BY 12Z. WINDS WILL TURN TO MORE WESTERLY WITH THE FRONT AS CEILINGS AND VSBYS RETURN TO VFR. WHILE THERE MAY BE A WEAKENING TREND IN WINDS...EXPECT THERE WILL STILL BE SOME SPORADIC WIND GUSTS THROUGH THE MORNING HOURS...WITH WIDESPREAD WIND GUSTS TO 20-25KT OUT OF THE WEST DURING THE DAY. OUTLOOK...VFR CONDITIONS ARE THEN EXPECTED TO PREVAIL THROUGH EARLY NEXT WEEK. ALTHOUGH...A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE AREA...ONE FRIDAY MORNING AND ONE SATURDAY NIGHT AND COULD PRODUCE A PERIOD OF INCREASED CLOUDINESS...WITH EVEN A SMALL POSSIBILITY OF SOME SPRINKLES OR FLURRIES. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY THROUGH 4 AM EST THIS MORNING FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...CBL/SMITH NEAR TERM...SMITH SHORT TERM...HARTFIELD LONG TERM...MLM AVIATION...KRR/SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EST THU JAN 31 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE STATE EARLY THIS MORNING....FOLLOWED BY COLDER AND DRIER AIR TODAY. A WEAK AND MOSTLY DRY COLD FRONT SYSTEM WILL CROSS THE AREA EARLY FRIDAY WITH HIGH PRESSURE BUILDING BACK IN FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 AM THURSDAY... ...A WIND ADVISORY ALSO REMAINS IN EFFECT ACROSS ALL OF CENTRAL NC THROUGH 4 AM LST... SQUALL LINE HAS PUSHES EAST OF THE CWA AND TO TORNADO WATCH WAS ALLOWED TO EXPIRE AT 2AM. WINDS IMMEDIATELY BEHIND THE LINE CONTINUE TO GUST TO 30-35KT...BUT DIE OFF WITH WESTWARD EXTENT AWAY FROM THE LINE. THE IS AN AREA OF STRONGER GUSTS OVER NORTHERN GA AND WESTERN SC...BUT HRRR WIND GUST FIELDS SUGGEST THESE WINDS WILL SHIFT EAST ACROSS SC. THUS...WE WILL ALLOW THE WIND ADVISORY TO EXPIRE AT 4AM. THE COLD FRONT...CURRENTLY EMERGING EAST OF THE MOUNTAINS..WILL PUSH EAST ACROSS THE CWA THIS MORNING AND IN TO THE COASTAL PLAIN BY 12Z. EXPECT WINDS WILL GUST PERIODICALLY TO AROUND 20KT WITH THE FRONT...THEN BECOME MORE CONSISTENT IN THE 20-25KT RANGE OUT OF THE WEST BEHIND THE FRONT TODAY. A FEW SHOWERS ARE POSSIBLE ALONG THE FRONT...MAINLY NORTH...AND DRYING ALOFT SHOULD LIMIT COVERAGE IN THE SOUTH. DESPITE CLEARING BEHIND THE FRONT...MODEST COLD ADVECTION WILL DOMINATE THE FIRST HALF OF THE DAY... KEEPING TEMPS FROM RISING MORE THAN 4-6 DEGREES ON MOST PLACES...RANGING FROM THE MID 40S NORTHWEST TO LOWER 50S SOUTHEAST. ANOTHER SHORTWAVE TROUGH DIGGING SOUTHEAST OUT OF CANADA WILL SWING ACROSS THE MID ATLANTIC STATES LATE TONIGHT. STRENGTHENING DPVA AND A BRIEF SHOT OF 60-80M HEIGHT FALLS FOCUSED ALONG THE NC/VA BORDER AND NORTHWARD...COMBINED WITH A BAND OF MID LEVEL MOISTURE CROSSING THE MOUNTAINS MAY BE SUFFICIENT TO CAUSE FLURRIES...MAINLY IN THE 09-12Z TIME FRAME. THE GFS HAS THE MOST ABUNDANT MOISTURE IN GENERAL...WITH MOISTURE REACHING TO -10C IN A BAND THAT SPANS THE ENTIRE CWA. HOWEVER...MOISTURE WITHIN THE ICE NUCLEATION ZONE IS ONLY PRESENT NORTH OF I-40 AND MOST PRONOUNCED NEAR THE NC/VA BORDER. THE LIMITED DURATION OF LIFT AND MOISTURE..AS WELL AS A RELATIVELY DRY BOUNDARY LAYER AND POTENTIAL FOR SUBLIMATION...WILL KEEP THIS TO A NO IMPACT EVENT. LOWS IN THE UPPER 20S TO LOWER 30S. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 150 PM WEDNESDAY... COLD FRONT WILL BE WELL OFFSHORE BY DAYBREAK WITH HIGH PRESSURE INITIALLY BUILDING ACROSS THE GULF STATES AND INTO THE REGION BEHIND THE FRONT. MILD ORIGIN OF THE HIGH AND ENSUING WESTERLY FLOW WILL ALLOW HIGHS ON THURSDAY TO REACH NEAR NORMAL...IN THE UPPER 40S TO LOWER 50S AND WINDS WILL BE DIMINISHING AS THE PRESSURE GRADIENT LOOSENS...LOOKING AT UP TO 15 MPH SUSTAINED WESTERLY WINDS WITH GUSTS TO PERHAPS 25 MPH. A REINFORCING SHORT WAVE WILL BE DIGGING INTO THE DOMINANT EAST COAST TROF LATE THURSDAY NIGHT...POSSIBLY SQUEEZING OUT SOME ISOLATED FLURRIES ALONG THE NORTHWEST TIER AS IT CROSSES THE MOUNTAINS. MINS THURSDAY NIGHT WILL BE AROUND 30...AND THE MAIN SENSIBLE IMPACT FROM THIS SHORT WAVE WILL BE TO SHARPEN THE NORTHWEST FLOW INTO THE TROF AND INITIATE STRONGER COLD AIR ADVECTION ON FRIDAY...WHEN HIGHS WILL STRUGGLE TO GET OUT OF THE 30S IN THE NORTHWEST...AND MAX OUT IN THE MID 40S IN THE SOUTHEAST. HIGH PRESSURE SETTLING OVERHEAD WILL LOCK THE COLD AIR IN OVERNIGHT...AND UNDER CLEAR SKIES...MINS FRIDAY NIGHT WILL BOTTOM OUT IN THE LOWER 20S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 150 PM WEDNESDAY... MOSTLY CLEAR SKIES WITH HIGH PRESSURE OVERHEAD SATURDAY WILL ALLOW HIGH TEMPERATURES TO CLIMB BACK TOWARDS SEASONABLE READINGS...IN THE 45 TO 50 DEGREE RANGE. THIS HIGH WILL SHIFT QUICKLY OFFSHORE AND A FAST MOVING MID LEVEL CLIPPER SYSTEM WILL DIG INTO THE OHIO VALLEY ON SATURDAY NIGHT...POSSIBLY PRODUCING SOME LIGHT RAIN OR SNOW SHOWERS AS IT TRAVERSES THE AREA...WITH LITTLE TO NO ACCUMULATION. THE ASSOCIATED CLOUDINESS WILL PREVENT TEMPERATURES FROM CRASHING HARD SATURDAY NIGHT...HOWEVER...WITH SUNDAY MORNING LOWS AROUND 30. THE WARMER START AND INCREASING SUN EXPECTED ON SUNDAY WILL ALLOW HIGHS TO REBOUND FURTHER...INTO THE SEASONABLE LOWER 50S OVER MOST OF THE AREA. THE EAST COAST TROF AXIS SHIFTS OFFSHORE AND UPPER FLOW WILL NOT BE AS AMPLIFIED EARLY NEXT WEEK. ANOTHER REINFORCING BACKDOOR COLD FRONT WILL BE SLOWLY EDGING SOUTH AND POTENTIALLY STALLING ACROSS THE MID ATLANTIC ON TUESDAY INTO WEDNESDAY...BUT MOISTURE WILL BE LACKING AND FORCING WILL BE UNFOCUSED IN THE WEAKER UPPER FLOW. AT THIS POINT THE WEATHER MONDAY THROUGH WEDNESDAY LOOKS DRY AND SEASONABLY MILD WITH HIGHS MOSTLY IN THE LOW TO MID 50S EACH DAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 1250 AM THURSDAY... SQUALL LINE CURRENTLY EXTENDS FROM KAVC TO KJNX TO BETWEEN KFAY AND KCTZ...MOVING EAST AT AROUND 30 MPH. STRONGEST SOUTHERLY WINDS CONTINUE ALONG AND AHEAD OF THE LINE WHERE 35-40KT GUSTS ARE REPORTED. HEAVY RAIN AND A SHORT PERIOD OF IFR/LIFR VSBYS AND CEILINGS WILL OCCUR AT KRWI BETWEEN 06Z AND 07Z. BEHIND THE LINE...SOUTHWESTERLY WINDS WILL CONTINUE TO GUST TO 25-30KT IMMEDIATELY BEHIND THE LINE...WITH THE STRONGEST GUSTS LIKELY TO ACCOMPANY SCATTERED SHOWERS THROUGH 09Z. THE MAIN COLD FRONT IS CURRENTLY CROSSING THE MOUNTAINS AND WILL CROSS THE AREAS BY 12Z. WINDS WILL TURN TO MORE WESTERLY WITH THE FRONT AS CEILINGS AND VSBYS RETURN TO VFR. WHILE THERE MAY BE A WEAKENING TREND IN WINDS...EXPECT THERE WILL STILL BE SOME SPORADIC WIND GUSTS THROUGH THE MORNING HOURS...WITH WIDESPREAD WIND GUSTS TO 20-25KT OUT OF THE WEST DURING THE DAY. OUTLOOK...VFR CONDITIONS ARE THEN EXPECTED TO PREVAIL THROUGH EARLY NEXT WEEK. ALTHOUGH...A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE AREA...ONE FRIDAY MORNING AND ONE SATURDAY NIGHT AND COULD PRODUCE A PERIOD OF INCREASED CLOUDINESS...WITH EVEN A SMALL POSSIBILITY OF SOME SPRINKLES OR FLURRIES. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY THROUGH 4 AM EST THIS MORNING FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...CBL/SMITH NEAR TERM...SMITH SHORT TERM...MLM LONG TERM...MLM AVIATION...KRR/SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
115 AM EST THU JAN 31 2013 .SYNOPSIS... WINDY AND MILD CONDITIONS WILL CONTINUE AHEAD OF A STRONG COLD FRONT. FAST MOVING SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT COULD PRODUCE LOCALIZED DAMAGING WIND GUSTS. DRY AND COOL CONDITIONS WILL FOLLOW THE FRONT THURSDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE MOVES INTO THE REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1045 PM WEDNESDAY...TORNADO WATCH REMAINS IN EFFECT FOR THE ENTIRE ILM CWA THRU 2 AM. MAIN ADJUSTMENT THIS UPDATE HAS BEEN APPLIED TO THE TIMING OF THE MAIN LINE OF CONVECTION CROSSING THE AREA. LATEST KLTX 88D TRENDS...RADAR MOSAIC OF THE SE U.S TRENDS...AND HRRR MODEL OUTPUT...INDICATE VERY LITTLE CONVECTION TO DEVELOP AHEAD OF THE APPROACHING LINE. THIS DUE TO A STABLE SFC BASED MARINE LAYER HAVING PROGRESSED WELL INLAND UNDER THE STRONG SSE-SSW LOW LEVEL WINDS. AT THIS POINT...DO NOT ANTICIPATE ANY ROGUE CONVECTIVE CELLS WELL AHEAD OF THIS LINE. HOWEVER...THE STRONG DYNAMICS ASSOCIATED WITH THE NEARLY SOLID LINE OF THE CONVECTION ITSELF CONTINUES TO WARRANT THE FORECAST OF STRONG TO SEVERE CONVECTION...WITH DAMAGING WIND GUSTS THE MAIN CONCERN. IN ADDITION...AN ISOLATED TORNADO REMAINS POSSIBLE DUE TO SUPPORTIVE DIRECTIONAL AND SPEED SHEAR ESPECIALLY AT THE LOWER LEVELS. THIS ILLUSTRATED NICELY BY 00Z UPPER AIR SOUNDING HODOGRAPHS. CONTINUED TWEAKING NEEDED FOR THE OVERNIGHT TEMP/DEWPT TRENDS...MAINLY DEALING WITH THE POST FRONTAL AIRMASS ADVECTING ACROSS THE FA LATE TONIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...STRONG WESTERLY WINDS WILL ADVECT MUCH COLDER AND DRIER AIR INTO REGION BEHIND EXITING COLD FRONT LOCATED WELL OFF THE COAST BY THURS MORNING. A VERY BROAD MID TO UPPER TROUGH WILL SHIFT EAST THROUGH THE PERIOD FINALLY LIFTING OFF TO THE NORTHEAST BY FRI NIGHT. AS THIS TROUGH MOVES EAST IT WILL DRIVE A SECONDARY BOUNDARY THROUGH THE AREA BY FRI MORNING. THIS WILL PROVIDE A REINFORCING SHOT OF COLD AND DRY AIR INTO THE AREA AS DEEP NW FLOW SETS UP ON FRIDAY. OVERALL A POTENT STORM SYSTEM WILL LIFT OFF TO THE NORTHEAST AS HIGH PRESSURE RIDGES UP FROM THE GULF COAST ON THURSDAY...BUT STRONG HIGH PRESSURE WILL BUILD DOWN FROM CANADA REACHING INTO THE CENTRAL CONUS BY THURS NIGHT AND SHIFTING EAST OVER THE LOCAL AREA BY LATE FRI INTO EARLY SAT. THIS WILL MAINTAIN A TIGHTENED GRADIENT FLOW THROUGH THURS AND THEN WINDS MAY BACK SLIGHTLY BEFORE NEXT DRY FRONTAL BOUNDARY MOVES THROUGH EARLY FRI WITH A SPIKE UP OF WINDS BEFORE FINALLY DIMINISHING AND VEERING MORE NORTH BY FRI NIGHT. THESE STRONG WEST TO NORTHWEST WINDS WILL MAINTAIN CAA THROUGH MUCH OF THE PERIOD. THERE WILL ONLY BE A BRIEF PERIOD OF MORE NEUTRAL ADVECTION AHEAD OF DRY COLD FRONT FRI MORNING. THEREFORE 850 TEMPS DROP FROM 13C JUST AHEAD OF INITIAL COLD FRONT EARLY THURS MORNING DOWN LESS THAN 0C BY THURS AFTN AND THEN WILL DROP AN ADDITIONAL SEVERAL DEGREES DOWN TO -8C BY FRI EVENING. TEMPS REACHING THE MID 50S...ALREADY 20 DEGREES COOLER THAN ON THURS...WILL HAVE TROUBLE REACHING INTO THE 50S ON FRI AS COLD ARCTIC HIGH PRESSURE BUILDS DOWN INTO THE AREA. OVERNIGHT LOWS WILL DROP DOWN TOWARD FREEZING THURS NIGHT IN CAA BUT FRI NIGHT TEMPS WILL PLUMMET ONCE WINDS DROP OFF IN THE EVENING. A MUCH MORE IDEAL RADIATIONAL COOLING NIGHT WILL OCCUR ON FRIDAY NIGHT AS HIGH SHIFTS OVERHEAD...MAKING FOR ONE OF THE COLDEST NIGHTS OF THE SEASON THUS FAR...WITH WIDESPREAD READINGS IN THE 20S. DRY AIR WILL RUN SIMILAR TO TEMPS WITH A MAJOR DROP OFF BEHIND FIRST FRONT AND THEN A PLATEAU AND MINOR INCREASE JUST AHEAD OF DRY POLAR COLD FRONT FRI MORNING AND THEN ANOTHER NOSE DIVE THROUGH FRI AFTN. THE PCP WATER DROP OFF FROM 1.6 INCHES VERY EARLY THURS MORNING DOWN TO A QUARTER OF AN INCH BY LATE THURS MORNING AND THEN DOWN CLOSE TO A TENTH OF AN INCH BY FRI AFTN. WITH SUCH A DRY AIR MASS IN PLACE...EXPECT SUNSHINE THROUGH MOST OF THE PERIOD. MAY SEE SOME CLOUDS WITH LINGERING MOISTURE THROUGH THURS MORNING AFTER RAINFALL FROM FRONT...AND A SLIGHT SPIKE AHEAD OF FRONT FRI MORNING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 PM WEDNESDAY...A RATHER REPETITIVE PATTERN FOR THE EXTENDED AS AREAS OF HIGH PRESSURE PUSH OFFSHORE AHEAD OF A SERIES OF WEAK COLD FRONTS. FIRST OF THESE OCCURS SATURDAY AS DIFFUSE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE...LEAVING A BRIEF PERIOD OF MOIST RETURN FLOW INTO THE CAROLINAS. THIS IS JUST IN ADVANCE OF A COLD FRONT WHICH WILL CROSS THE AREA VERY EARLY SUNDAY MORNING. LIMITED FORCING COMBINED WITH ONLY MARGINAL PWATS SUGGESTS FROPA WILL BE DRY...AND ONLY ACT TO REINFORCE THE COOL AIR. HOWEVER...ANY WEAK CAA REMAINS WELL DISPLACED BEHIND THE FRONT...SO SUNDAY WILL END UP BEING WARMER THAN SATURDAY...ALTHOUGH BOTH DAYS WILL BE AROUND TO SLIGHTLY BELOW CLIMO. ANOTHER LARGE BUT WEAK AREA OF HIGH PRESSURE BUILDS DOWN FROM THE NW LATE SUNDAY AND PERSISTS INTO TUESDAY WHILE SLOWLY DRIFTING ACROSS THE REGION. THIS CONTINUES THE COOL AND DRY WEATHER WITH NEAR TO SLIGHTLY-BELOW SEASONABLE TEMPS. THIS HIGH PRESSURE THEN DRIFTS OFFSHORE TUESDAY AHEAD OF ANOTHER COLD FRONT PROGGED TO CROSS THE AREA LATE IN THE DAY. GUIDANCE SHOWING CONSIDERABLE AMPLITUDE DIFFERENCES IN THE TROUGH DRIVING THIS FRONT WHICH WILL HAVE SIGNIFICANT IMPACT ON PRECIP POTENTIAL. FOR NOW WILL KEEP INHERITED SCHC/SILENT POP FOR D6 SINCE BENEFICIAL CHANGES CANNOT BE MADE AT THIS TIME. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD THOUGH AHEAD OF THE COLD FRONT...WITH TEMPS RETURNING TO BELOW CLIMO FOR WEDNESDAY AS ANOTHER AREA OF HIGH PRESSURE RIDGES DOWN FROM THE NW. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 06Z...VFR WITH AREAS OF SHORT-LIVED MVFR/IFR AS SQUALL LINE WITH SHOWERS/ISOLATED THUNDERSTORMS CONTINUES TO PUSH ACROSS THE AREA OVER THE NEXT FEW HOURS. VFR EXPECTED THROUGH THE REMAINDER OF THE VALID TAF PERIOD AFTER 10Z. MAIN LINE OF SHOWERS IS NOW EAST OF KFLO/KLBT/KMYR...CURRENTLY AFFECTING KCRE...AND PROGRESSING EASTWARD. EXPECT THIS ACTIVITY TO REACH KILM WITHIN THE NEXT HOUR...BETWEEN 0645Z AND 0700Z. THIS SQUALL LINE HAS A HISTORY OF PRODUCING STRONG WINDS WITH SUSTAINED SPEEDS OF 20+ KTS AND GUSTS UP TO 40+ KTS...ALONG WITH SHORT-LIVED MVFR/IFR CONDITIONS DUE TO HEAVY RAIN. WITH CURRENT TREND AND GUIDANCE... EXPECT MAIN SQUALL LINE TO PUSH OFFSHORE BY 0715Z. AFTER THE PASSAGE OF THE COLD FRONT...THE AREA WILL SEE A SUDDEN WIND SHIFT...POST-FRONTAL RAIN POTENTIALLY CREATING MVFR/IFR CONDITIONS OVER THE NEXT FEW HOURS. HAVE INCLUDED LLWS IN CURRENT FCST...AND HAVE ISSUED AN AWW FOR KILM VALID UNTIL 0730Z FOR THE WINDSHIFT OF 60 DEGREES AND ASSOCIATED GUSTS UP TO 40+ KTS. CLEARING SKIES WILL LEAD TO VFR CONDITIONS ACROSS THE ENTIRE AREA BETWEEN 8-10Z. FOR THE REST OF THE PERIOD...EXPECT STRONG WESTERLY WINDS CONTINUING THROUGH THE AFTERNOON HOURS WITH GUSTS UP TO 25 KTS. GUSTS WILL SUBSIDE INTO THE EVENING HOURS. EXTENDED OUTLOOK...VFR THROUGH THE EXTENDED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM WEDNESDAY...SFC PG WINDS CONTINUE TO OVERSPREAD THE COASTAL WATERS...WITH WINDS OF 15 TO 30 KT SPEEDS ACROSS THE NEAR SHORE WATERS DUE TO SSTS IN THE LOW 50S. ACROSS THE OUTER WATERS OF THE ILM CWA WHERE SSTS INCREASE TO AROUND 60 DEGREES...LOOK FOR HIGHER WIND SPEEDS OF 25 TO 40 KT. WITH THE INCREASING OF SSE- SSW WINDS THIS EVENING. ..BUILDING SHORT PERIOD SEAS HAVE FINALLY RESPONDED. IE. SEAS AT THE OCEAN CREST PIER HAVE NOW CLIMBED TO 7 FT...THE ONSLOW BAY AND FRYING PAN SHOALS BUOYS HAVE CLIMBED TO 12-13 FT RESPECTIVELY...WITH SSTS MEASURED AT BOTH THESE BUOYS OF 60 AND 68 DEGREES RESPECTIVELY. OVERALL...LOOK FOR THIS RANGE OF WINDS AND SEA CONDITIONS TO PERSIST ACROSS THE FA WATERS UNTIL THE PASSAGE OF THE COLD FRONT BETWEEN 1 AM AND 5 AM. OVERALL...BUILDING SIGNIFICANT SEAS HAVE LEVELED OFF FOR THE REMAINDER OF THE OVERNIGHT...WITH ADJUSTMENTS UPWARDS NEEDED FOR THURSDAY FOR THE ILM WATERS FROM CAPE FEAR SOUTH TO MURRELLS INLET DUE TO THE STRONG WSW-W WIND DIRECTIONS KEEPING THE SEAS AGITATED. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...ALTHOUGH SEAS WILL BE ON THE DECREASE THROUGH MUCH OF THE PERIOD IN STRONG OFF SHORE FLOW...TIGHTENED GRADIENT FLOW AND COLD SURGE BEHIND FRONT THURS AND AGAIN ON FRI WILL MAINTAIN SEAS ABOVE SCA THROUGH A GOOD PORTION OF THE SHORT TERM PERIOD IN THE OUTER WATERS. WESTERLY WINDS UP AROUND 25 KTS WILL DROP THROUGH THURS ALLOWING OFF SHORE SEAS TO SUBSIDE FROM 8 TO 10 FT FRI MORNING DOWN TO 5 FT BY THURS NIGHT. WINDS WILL BACK SLIGHTLY TO THE SW THURS NIGHT INTO EARLY FRI AHEAD OF APPROACHING DRY COLD FRONT BEFORE SPIKING UP IN SURGE BEHIND FRONT. THIS WILL PRODUCE SEAS AROUND 6 FT ONCE AGAIN FOR A FEW HOURS ON FRI. THE NEAR SHORE WATERS WILL DECREASE THROUGH THURS IN OFF SHORE FLOW DOWN TO 2 TO 4 FT AND MAY SPIKE UP A BIT FRI MORNING BUT OVERALL WILL DROP OFF SOME MORE LATE FRI AS HIGH PRESSURE SHIFTS OVERHEAD ALLOWING FOR LOCAL SEAS TO DROP TO 2 TO 3 FT IN ALL WATERS. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 PM WEDNESDAY...OTHER THAN A WEAK COLD FRONT SUNDAY...DIFFUSE HIGH PRESSURE WILL DOMINATE THE WEATHER ACROSS THE WATERS THROUGH THE EXTENDED. ONE AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WATERS SATURDAY CREATING LIGHT AND VARIABLE WINDS...VEERING TO THE SW AND INCREASING TO AROUND 10 KTS LATE IN THE DAY. THIS AHEAD OF A COLD FRONT WHICH WILL CROSS DURING SUNDAY...TURNING WINDS TO THE W/NW AT 10-15 KTS ON SUNDAY BEFORE SLOWLY EASING TO LIGHT AND VARIABLE AGAIN MONDAY AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. SEAS WILL BE PRIMARILY WIND-DRIVEN THROUGH THE PERIOD...1-2 FT SATURDAY AND MONDAY...INCREASING FOR A SHORT TIME SUNDAY UP TO 2-4 FT WITH A NW WIND WAVE DOMINANT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR SCZ017-023- 024-032-033-039-053>056. NC...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NCZ087-096- 099-105>110. MARINE...GALE WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR AMZ250-252- 254-256. && $$ SYNOPSIS...RGZ NEAR TERM...DCH SHORT TERM...RGZ LONG TERM...JDW AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1119 PM EST WED JAN 30 2013 .SYNOPSIS... WINDY AND MILD CONDITIONS WILL CONTINUE AHEAD OF A STRONG COLD FRONT. FAST MOVING SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT COULD PRODUCE LOCALIZED DAMAGING WIND GUSTS. DRY AND COOL CONDITIONS WILL FOLLOW THE FRONT THURSDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE MOVES INTO THE REGION. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 1045 PM WEDNESDAY...TORNADO WATCH REMAINS IN EFFECT FOR THE ENTIRE ILM CWA THRU 2 AM. MAIN ADJUSTMENT THIS UPDATE HAS BEEN APPLIED TO THE TIMING OF THE MAIN LINE OF CONVECTION CROSSING THE AREA. LATEST KLTX 88D TRENDS...RADAR MOSAIC OF THE SE U.S TRENDS...AND HRRR MODEL OUTPUT...INDICATE VERY LITTLE CONVECTION TO DEVELOP AHEAD OF THE APPROACHING LINE. THIS DUE TO A STABLE SFC BASED MARINE LAYER HAVING PROGRESSED WELL INLAND UNDER THE STRONG SSE-SSW LOW LEVEL WINDS. AT THIS POINT...DO NOT ANTICIPATE ANY ROGUE CONVECTIVE CELLS WELL AHEAD OF THIS LINE. HOWEVER...THE STRONG DYNAMICS ASSOCIATED WITH THE NEARLY SOLID LINE OF THE CONVECTION ITSELF CONTINUES TO WARRANT THE FORECAST OF STRONG TO SEVERE CONVECTION...WITH DAMAGING WIND GUSTS THE MAIN CONCERN. IN ADDITION...AN ISOLATED TORNADO REMAINS POSSIBLE DUE TO SUPPORTIVE DIRECTIONAL AND SPEED SHEAR ESPECIALLY AT THE LOWER LEVELS. THIS ILLUSTRATED NICELY BY 00Z UPPER AIR SOUNDING HODOGRAPHS. CONTINUED TWEAKING NEEDED FOR THE OVERNIGHT TEMP/DEWPT TRENDS...MAINLY DEALING WITH THE POST FRONTAL AIRMASS ADVECTING ACROSS THE FA LATE TONIGHT. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...STRONG WESTERLY WINDS WILL ADVECT MUCH COLDER AND DRIER AIR INTO REGION BEHIND EXITING COLD FRONT LOCATED WELL OFF THE COAST BY THURS MORNING. A VERY BROAD MID TO UPPER TROUGH WILL SHIFT EAST THROUGH THE PERIOD FINALLY LIFTING OFF TO THE NORTHEAST BY FRI NIGHT. AS THIS TROUGH MOVES EAST IT WILL DRIVE A SECONDARY BOUNDARY THROUGH THE AREA BY FRI MORNING. THIS WILL PROVIDE A REINFORCING SHOT OF COLD AND DRY AIR INTO THE AREA AS DEEP NW FLOW SETS UP ON FRIDAY. OVERALL A POTENT STORM SYSTEM WILL LIFT OFF TO THE NORTHEAST AS HIGH PRESSURE RIDGES UP FROM THE GULF COAST ON THURSDAY...BUT STRONG HIGH PRESSURE WILL BUILD DOWN FROM CANADA REACHING INTO THE CENTRAL CONUS BY THURS NIGHT AND SHIFTING EAST OVER THE LOCAL AREA BY LATE FRI INTO EARLY SAT. THIS WILL MAINTAIN A TIGHTENED GRADIENT FLOW THROUGH THURS AND THEN WINDS MAY BACK SLIGHTLY BEFORE NEXT DRY FRONTAL BOUNDARY MOVES THROUGH EARLY FRI WITH A SPIKE UP OF WINDS BEFORE FINALLY DIMINISHING AND VEERING MORE NORTH BY FRI NIGHT. THESE STRONG WEST TO NORTHWEST WINDS WILL MAINTAIN CAA THROUGH MUCH OF THE PERIOD. THERE WILL ONLY BE A BRIEF PERIOD OF MORE NEUTRAL ADVECTION AHEAD OF DRY COLD FRONT FRI MORNING. THEREFORE 850 TEMPS DROP FROM 13C JUST AHEAD OF INITIAL COLD FRONT EARLY THURS MORNING DOWN LESS THAN 0C BY THURS AFTN AND THEN WILL DROP AN ADDITIONAL SEVERAL DEGREES DOWN TO -8C BY FRI EVENING. TEMPS REACHING THE MID 50S...ALREADY 20 DEGREES COOLER THAN ON THURS...WILL HAVE TROUBLE REACHING INTO THE 50S ON FRI AS COLD ARCTIC HIGH PRESSURE BUILDS DOWN INTO THE AREA. OVERNIGHT LOWS WILL DROP DOWN TOWARD FREEZING THURS NIGHT IN CAA BUT FRI NIGHT TEMPS WILL PLUMMET ONCE WINDS DROP OFF IN THE EVENING. A MUCH MORE IDEAL RADIATIONAL COOLING NIGHT WILL OCCUR ON FRIDAY NIGHT AS HIGH SHIFTS OVERHEAD...MAKING FOR ONE OF THE COLDEST NIGHTS OF THE SEASON THUS FAR...WITH WIDESPREAD READINGS IN THE 20S. DRY AIR WILL RUN SIMILAR TO TEMPS WITH A MAJOR DROP OFF BEHIND FIRST FRONT AND THEN A PLATEAU AND MINOR INCREASE JUST AHEAD OF DRY POLAR COLD FRONT FRI MORNING AND THEN ANOTHER NOSE DIVE THROUGH FRI AFTN. THE PCP WATER DROP OFF FROM 1.6 INCHES VERY EARLY THURS MORNING DOWN TO A QUARTER OF AN INCH BY LATE THURS MORNING AND THEN DOWN CLOSE TO A TENTH OF AN INCH BY FRI AFTN. WITH SUCH A DRY AIR MASS IN PLACE...EXPECT SUNSHINE THROUGH MOST OF THE PERIOD. MAY SEE SOME CLOUDS WITH LINGERING MOISTURE THROUGH THURS MORNING AFTER RAINFALL FROM FRONT...AND A SLIGHT SPIKE AHEAD OF FRONT FRI MORNING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 PM WEDNESDAY...A RATHER REPETITIVE PATTERN FOR THE EXTENDED AS AREAS OF HIGH PRESSURE PUSH OFFSHORE AHEAD OF A SERIES OF WEAK COLD FRONTS. FIRST OF THESE OCCURS SATURDAY AS DIFFUSE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE...LEAVING A BRIEF PERIOD OF MOIST RETURN FLOW INTO THE CAROLINAS. THIS IS JUST IN ADVANCE OF A COLD FRONT WHICH WILL CROSS THE AREA VERY EARLY SUNDAY MORNING. LIMITED FORCING COMBINED WITH ONLY MARGINAL PWATS SUGGESTS FROPA WILL BE DRY...AND ONLY ACT TO REINFORCE THE COOL AIR. HOWEVER...ANY WEAK CAA REMAINS WELL DISPLACED BEHIND THE FRONT...SO SUNDAY WILL END UP BEING WARMER THAN SATURDAY...ALTHOUGH BOTH DAYS WILL BE AROUND TO SLIGHTLY BELOW CLIMO. ANOTHER LARGE BUT WEAK AREA OF HIGH PRESSURE BUILDS DOWN FROM THE NW LATE SUNDAY AND PERSISTS INTO TUESDAY WHILE SLOWLY DRIFTING ACROSS THE REGION. THIS CONTINUES THE COOL AND DRY WEATHER WITH NEAR TO SLIGHTLY-BELOW SEASONABLE TEMPS. THIS HIGH PRESSURE THEN DRIFTS OFFSHORE TUESDAY AHEAD OF ANOTHER COLD FRONT PROGGED TO CROSS THE AREA LATE IN THE DAY. GUIDANCE SHOWING CONSIDERABLE AMPLITUDE DIFFERENCES IN THE TROUGH DRIVING THIS FRONT WHICH WILL HAVE SIGNIFICANT IMPACT ON PRECIP POTENTIAL. FOR NOW WILL KEEP INHERITED SCHC/SILENT POP FOR D6 SINCE BENEFICIAL CHANGES CANNOT BE MADE AT THIS TIME. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD THOUGH AHEAD OF THE COLD FRONT...WITH TEMPS RETURNING TO BELOW CLIMO FOR WEDNESDAY AS ANOTHER AREA OF HIGH PRESSURE RIDGES DOWN FROM THE NW. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... AS OF 00Z...STRONG COLD FRONT TO IMPACT THE TERMINALS TONIGHT WITH GUSTY WINDS AND A POTENTIAL SQUALL LINE WITH SHOWERS/ISOLATED THUNDERSTORMS. COLD FRONT CURRENTLY ACROSS WESTERN PORTIONS OF SC/NC WILL PUSH EAST TONIGHT AND BE ACCOMPANIED BY A LINE OF SHOWERS WITH ISOLATED THUNDERSTORMS. HRRR APPEARS TO BE INITIALIZING BETTER THAN ANY OF THE OTHER HIGH-RES GUIDANCE...SO HAVE RELIED HEAVILY ON THIS MODEL FOR TIMING CONVECTION AT THE TERMINALS...AND EXPECT THE SQUALL LINE TO IMPACT FLO/LBT AROUND 03Z...RACING EAST TO ILM AROUND 06Z. ATTM...NO IFR HAS BEEN INTRODUCED INTO THE CURRENT SET OF TAFS DUE TO UNCERTAINTY IN EXACT TIMING AND LIKELY SHORT-DURATION OF ANY PRECIP INDUCED IFR. PREFER TO HANDLE ANY IFR WITH AMD/TEMPO GROUPS AS THE CONVECTION UNFOLDS. HAVE SHOWN A 2-HR TEMPO GROUP AT ALL TERMINALS FOR THE HEAVIEST CONVECTION WITH MVFR AND INCREASED WIND GUSTS...BUT STRONGER GUSTS ARE POSSIBLE THAN WHAT IS CURRENTLY DEPICTED. OTHER CONCERN IS THE STRONG PRE-FRONTAL AND POST-FRONTAL WINDS. S/SW WINDS WILL CONTINUE TO INCREASE TONIGHT AS A STRENGTHENING LOW LEVEL JET MOVES OVERHEAD. FOR THIS REASON HAVE SHOWN INCREASING LLWS IN ALL TAFS WITH 30 KT GUSTS LIKELY THROUGH THE NIGHT...EVEN OUTSIDE OF CONVECTION. A SUDDEN WIND SHIFT WILL OCCUR WITH THE FROPA TONIGHT...AND AWWS MAY BE REQUIRED FOR ILM/MYR LATER TONIGHT AS THE FRONT CROSSES...AND WINDS SHIFT SUDDENLY TO THE WEST. RAPID DRYING OCCURS BEHIND THE FRONT AND SKC WILL BECOME THE SKY CONDITION ON THURSDAY. ALTHOUGH IT WILL BE CLEAR...STRONG WESTERLY WINDS WILL PERSIST THROUGH THE DAY...GUSTING TO 25 KTS THROUGH THE END OF THE VALID PERIOD. EXTENDED OUTLOOK...VFR THROUGH THE EXTENDED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM WEDNESDAY...SFC PG WINDS CONTINUE TO OVERSPREAD THE COASTAL WATERS...WITH WINDS OF 15 TO 30 KT SPEEDS ACROSS THE NEAR SHORE WATERS DUE TO SSTS IN THE LOW 50S. ACROSS THE OUTER WATERS OF THE ILM CWA WHERE SSTS INCREASE TO AROUND 60 DEGREES...LOOK FOR HIGHER WIND SPEEDS OF 25 TO 40 KT. WITH THE INCREASING OF SSE- SSW WINDS THIS EVENING. ..BUILDING SHORT PERIOD SEAS HAVE FINALLY RESPONDED. IE. SEAS AT THE OCEAN CREST PIER HAVE NOW CLIMBED TO 7 FT...THE ONSLOW BAY AND FRYING PAN SHOALS BUOYS HAVE CLIMBED TO 12-13 FT RESPECTIVELY...WITH SSTS MEASURED AT BOTH THESE BUOYS OF 60 AND 68 DEGREES RESPECTIVELY. OVERALL...LOOK FOR THIS RANGE OF WINDS AND SEA CONDITIONS TO PERSIST ACROSS THE FA WATERS UNTIL THE PASSAGE OF THE COLD FRONT BETWEEN 1 AM AND 5 AM. OVERALL...BUILDING SIGNIFICANT SEAS HAVE LEVELED OFF FOR THE REMAINDER OF THE OVERNIGHT...WITH ADJUSTMENTS UPWARDS NEEDED FOR THURSDAY FOR THE ILM WATERS FROM CAPE FEAR SOUTH TO MURRELLS INLET DUE TO THE STRONG WSW-W WIND DIRECTIONS KEEPING THE SEAS AGITATED. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...ALTHOUGH SEAS WILL BE ON THE DECREASE THROUGH MUCH OF THE PERIOD IN STRONG OFF SHORE FLOW...TIGHTENED GRADIENT FLOW AND COLD SURGE BEHIND FRONT THURS AND AGAIN ON FRI WILL MAINTAIN SEAS ABOVE SCA THROUGH A GOOD PORTION OF THE SHORT TERM PERIOD IN THE OUTER WATERS. WESTERLY WINDS UP AROUND 25 KTS WILL DROP THROUGH THURS ALLOWING OFF SHORE SEAS TO SUBSIDE FROM 8 TO 10 FT FRI MORNING DOWN TO 5 FT BY THURS NIGHT. WINDS WILL BACK SLIGHTLY TO THE SW THURS NIGHT INTO EARLY FRI AHEAD OF APPROACHING DRY COLD FRONT BEFORE SPIKING UP IN SURGE BEHIND FRONT. THIS WILL PRODUCE SEAS AROUND 6 FT ONCE AGAIN FOR A FEW HOURS ON FRI. THE NEAR SHORE WATERS WILL DECREASE THROUGH THURS IN OFF SHORE FLOW DOWN TO 2 TO 4 FT AND MAY SPIKE UP A BIT FRI MORNING BUT OVERALL WILL DROP OFF SOME MORE LATE FRI AS HIGH PRESSURE SHIFTS OVERHEAD ALLOWING FOR LOCAL SEAS TO DROP TO 2 TO 3 FT IN ALL WATERS. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 PM WEDNESDAY...OTHER THAN A WEAK COLD FRONT SUNDAY...DIFFUSE HIGH PRESSURE WILL DOMINATE THE WEATHER ACROSS THE WATERS THROUGH THE EXTENDED. ONE AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WATERS SATURDAY CREATING LIGHT AND VARIABLE WINDS...VEERING TO THE SW AND INCREASING TO AROUND 10 KTS LATE IN THE DAY. THIS AHEAD OF A COLD FRONT WHICH WILL CROSS DURING SUNDAY...TURNING WINDS TO THE W/NW AT 10-15 KTS ON SUNDAY BEFORE SLOWLY EASING TO LIGHT AND VARIABLE AGAIN MONDAY AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. SEAS WILL BE PRIMARILY WIND-DRIVEN THROUGH THE PERIOD...1-2 FT SATURDAY AND MONDAY...INCREASING FOR A SHORT TIME SUNDAY UP TO 2-4 FT WITH A NW WIND WAVE DOMINANT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR SCZ017-023-024-032- 033-039-053>056. NC...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR NCZ087-096-099- 105>110. MARINE...GALE WARNING UNTIL 6 AM EST THURSDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...RGZ NEAR TERM...DCH SHORT TERM...RGZ LONG TERM...JDW AVIATION...JDW/SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
937 PM EST WED JAN 30 2013 .SYNOPSIS... WINDY AND MILD CONDITIONS WILL CONTINUE AHEAD OF A STRONG COLD FRONT. FAST MOVING SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT COULD PRODUCE LOCALIZED DAMAGING WIND GUSTS. DRY AND COOL CONDITIONS WILL FOLLOW THE FRONT THURSDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE MOVES INTO THE REGION. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 845 PM WEDNESDAY...MAIN ADJUSTMENT ASSOCIATED WITH THE TORNADO WATCH IN EFFECT FOR THE ENTIRE ILM CWA THRU 2 AM. IN ADDITION...ADJUSTMENTS TO THE TIMING...OF THE APPROACH AND DEPARTURE OF THE MAIN LINE OF CONVECTION HAS ALSO BEEN APPLIED. LATEST 88D MOSAIC INDICATES VERY LITTLE CONVECTION DEVELOPING AHEAD OF THE APPROACHING LINE...MAINLY DUE TO A STABLE MARINE SFC BASED LAYER HAVING PROGRESSED WELL INLAND UNDER THE STRONG SSE- SSW LOW LEVEL WINDS. AT THIS POINT...DO NOT ANTICIPATE THOSE ROGUE CONVECTIVE CELLS WELL AHEAD OF THIS LINE. HOWEVER...THE STRONG DYNAMICS ASSOCIATED WITH THE NEARLY SOLID LINE OF CONVECTION ITSELF CONTINUES TO WARRANT THE FORECAST OF STRONG TO SEVERE CONVECTION WITH DAMAGING WIND GUSTS...AND POSSIBLY A TORNADO DUE TO SUPPORTIVE DIRECTIONAL AND SPEED SHEAR. THIS ILLUSTRATED WELL BY 00Z UPPER AIR SOUNDING HODOGRAPHS. OVERNIGHT TEMP/DEWPT ONLY NEEDED TWEAKING WITH CURRENT VALUES APPLIED TO THE OVERNIGHT TEMP/DEWPT TRENDS. PREVIOUS DISCUSSION................................................. AS OF 300 PM WEDNESDAY...THE STRONG COLD FRONT EXTENDS FROM EASTERN TENNESSEE TO THE FLORIDA PANHANDLE AND IS CATCHING UP QUITE RAPIDLY WITH THE PREFRONTAL SQUALL LINE. ALTHOUGH THERE ARE STILL SOME TIMING DIFFERENCES AMONG THE VARIOUS 12Z MODELS...THE CONSENSUS IS FOR THE FRONT TO ARRIVE IN THE SC PEE DEE REGION JUST BEFORE MIDNIGHT...MOVING THROUGH THE GRAND STRAND AND ELIZABETHTOWN/ WHITEVILLE AREAS AROUND MIDNIGHT...THEN THROUGH WILMINGTON AND THE CAPE FEAR COAST AROUND 1 AM. THIS WILL BE A VERY QUICK EVENT FOR ANY ONE LOCATION AND THE SQUALL LINE SHOULD TRAVERSE OUR ENTIRE FORECAST AREA IN 3 HOURS OR LESS. STRONG SOUTH WINDS OUT AHEAD OF THE FRONT/SQUALL LINE HAVE GUSTED TO 39 MPH IN FLORENCE AND 36 MPH IN WILMINGTON. GUSTS OVER 40 MPH SHOULD DEVELOP BEFORE SUNSET AS STRONGER WINDS IN THE 1000-2000 FT LAYER GET ENTRAINED IN TURBULENT MIXING THROUGHOUT THE DAYTIME BOUNDARY LAYER. AS THE SURFACE COOLS DOWN TO 68-70 DEGREES THIS EVENING AND THE BOUNDARY LAYER FLATTENS TO ONLY A FEW HUNDRED FEET THICK...WINDS AS LOW AS 1000 FT AGL WILL INCREASE TO 40-50 KNOTS. SOME OF THIS MOMENTUM MAY STILL TUMBLE DOWN TO THE SURFACE WITH GUSTS UP 45 MPH EXPECTED. A SQUALL LINE CONSISTING OF LINEAR FORCED CONVECTION WITHIN A REGION OF HIGHLY CONVERGENT LOW-LEVEL FLOW JUST AHEAD OF THE FRONT WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS VIA HEAVY RAINFALL TRANSPORTING STRONG WINDS DOWN FROM ALOFT. CONVECTIVE CELLS... ASSUMING A 15000 FT CELL DEPTH AND MOVEMENT AT 70% OF THE MEAN FLOW...COULD MOVE AS QUICKLY AS 65 KNOTS. THE POTENTIAL FOR WIDESPREAD DAMAGING WINDS DOES EXIST. ASSUMING SURFACE TEMPS OF 68-70 DEGREES AND SURFACE DEWPOINTS IN THE LOWER 60S...SURFACE-BASED CAPE SHOULD REMAIN NEAR ZERO TONIGHT. HOWEVER THE SURFACE-BASED INVERSION WILL ALSO BE WEAK AND MAY NOT PROVIDE AN EFFECTIVE BARRIER TO STRONG WINDS PUNCHING DOWN FROM ALOFT. THE BEST POTENTIAL FOR SEVERE WEATHER SHOULD BE NEAR AND WEST OF I-95...BUT EVEN AT THE COAST THE THREAT IS STILL LARGE ENOUGH FOR CONCERN. SEVERE THUNDERSTORM WATCHES WILL PROBABLY BE NEEDED FOR THE AREA TONIGHT. THANKFULLY...THE SHALLOW DEPTH OF THE CONVECTION PLUS WEAK UPDRAFT STRENGTH SHOULD PRECLUDE ANY HAIL THREAT. AFTER THE FRONT SLIDES OFFSHORE...MUCH DRIER COOLER AIR WILL BUILD IN WITH CLEARING SKIES. LOWS SHOULD RANGE FROM 45-50. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...STRONG WESTERLY WINDS WILL ADVECT MUCH COLDER AND DRIER AIR INTO REGION BEHIND EXITING COLD FRONT LOCATED WELL OFF THE COAST BY THURS MORNING. A VERY BROAD MID TO UPPER TROUGH WILL SHIFT EAST THROUGH THE PERIOD FINALLY LIFTING OFF TO THE NORTHEAST BY FRI NIGHT. AS THIS TROUGH MOVES EAST IT WILL DRIVE A SECONDARY BOUNDARY THROUGH THE AREA BY FRI MORNING. THIS WILL PROVIDE A REINFORCING SHOT OF COLD AND DRY AIR INTO THE AREA AS DEEP NW FLOW SETS UP ON FRIDAY. OVERALL A POTENT STORM SYSTEM WILL LIFT OFF TO THE NORTHEAST AS HIGH PRESSURE RIDGES UP FROM THE GULF COAST ON THURSDAY...BUT STRONG HIGH PRESSURE WILL BUILD DOWN FROM CANADA REACHING INTO THE CENTRAL CONUS BY THURS NIGHT AND SHIFTING EAST OVER THE LOCAL AREA BY LATE FRI INTO EARLY SAT. THIS WILL MAINTAIN A TIGHTENED GRADIENT FLOW THROUGH THURS AND THEN WINDS MAY BACK SLIGHTLY BEFORE NEXT DRY FRONTAL BOUNDARY MOVES THROUGH EARLY FRI WITH A SPIKE UP OF WINDS BEFORE FINALLY DIMINISHING AND VEERING MORE NORTH BY FRI NIGHT. THESE STRONG WEST TO NORTHWEST WINDS WILL MAINTAIN CAA THROUGH MUCH OF THE PERIOD. THERE WILL ONLY BE A BRIEF PERIOD OF MORE NEUTRAL ADVECTION AHEAD OF DRY COLD FRONT FRI MORNING. THEREFORE 850 TEMPS DROP FROM 13C JUST AHEAD OF INITIAL COLD FRONT EARLY THURS MORNING DOWN LESS THAN 0C BY THURS AFTN AND THEN WILL DROP AN ADDITIONAL SEVERAL DEGREES DOWN TO -8C BY FRI EVENING. TEMPS REACHING THE MID 50S...ALREADY 20 DEGREES COOLER THAN ON THURS...WILL HAVE TROUBLE REACHING INTO THE 50S ON FRI AS COLD ARCTIC HIGH PRESSURE BUILDS DOWN INTO THE AREA. OVERNIGHT LOWS WILL DROP DOWN TOWARD FREEZING THURS NIGHT IN CAA BUT FRI NIGHT TEMPS WILL PLUMMET ONCE WINDS DROP OFF IN THE EVENING. A MUCH MORE IDEAL RADIATIONAL COOLING NIGHT WILL OCCUR ON FRIDAY NIGHT AS HIGH SHIFTS OVERHEAD...MAKING FOR ONE OF THE COLDEST NIGHTS OF THE SEASON THUS FAR...WITH WIDESPREAD READINGS IN THE 20S. DRY AIR WILL RUN SIMILAR TO TEMPS WITH A MAJOR DROP OFF BEHIND FIRST FRONT AND THEN A PLATEAU AND MINOR INCREASE JUST AHEAD OF DRY POLAR COLD FRONT FRI MORNING AND THEN ANOTHER NOSE DIVE THROUGH FRI AFTN. THE PCP WATER DROP OFF FROM 1.6 INCHES VERY EARLY THURS MORNING DOWN TO A QUARTER OF AN INCH BY LATE THURS MORNING AND THEN DOWN CLOSE TO A TENTH OF AN INCH BY FRI AFTN. WITH SUCH A DRY AIR MASS IN PLACE...EXPECT SUNSHINE THROUGH MOST OF THE PERIOD. MAY SEE SOME CLOUDS WITH LINGERING MOISTURE THROUGH THURS MORNING AFTER RAINFALL FROM FRONT...AND A SLIGHT SPIKE AHEAD OF FRONT FRI MORNING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 PM WEDNESDAY...A RATHER REPETITIVE PATTERN FOR THE EXTENDED AS AREAS OF HIGH PRESSURE PUSH OFFSHORE AHEAD OF A SERIES OF WEAK COLD FRONTS. FIRST OF THESE OCCURS SATURDAY AS DIFFUSE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE...LEAVING A BRIEF PERIOD OF MOIST RETURN FLOW INTO THE CAROLINAS. THIS IS JUST IN ADVANCE OF A COLD FRONT WHICH WILL CROSS THE AREA VERY EARLY SUNDAY MORNING. LIMITED FORCING COMBINED WITH ONLY MARGINAL PWATS SUGGESTS FROPA WILL BE DRY...AND ONLY ACT TO REINFORCE THE COOL AIR. HOWEVER...ANY WEAK CAA REMAINS WELL DISPLACED BEHIND THE FRONT...SO SUNDAY WILL END UP BEING WARMER THAN SATURDAY...ALTHOUGH BOTH DAYS WILL BE AROUND TO SLIGHTLY BELOW CLIMO. ANOTHER LARGE BUT WEAK AREA OF HIGH PRESSURE BUILDS DOWN FROM THE NW LATE SUNDAY AND PERSISTS INTO TUESDAY WHILE SLOWLY DRIFTING ACROSS THE REGION. THIS CONTINUES THE COOL AND DRY WEATHER WITH NEAR TO SLIGHTLY-BELOW SEASONABLE TEMPS. THIS HIGH PRESSURE THEN DRIFTS OFFSHORE TUESDAY AHEAD OF ANOTHER COLD FRONT PROGGED TO CROSS THE AREA LATE IN THE DAY. GUIDANCE SHOWING CONSIDERABLE AMPLITUDE DIFFERENCES IN THE TROUGH DRIVING THIS FRONT WHICH WILL HAVE SIGNIFICANT IMPACT ON PRECIP POTENTIAL. FOR NOW WILL KEEP INHERITED SCHC/SILENT POP FOR D6 SINCE BENEFICIAL CHANGES CANNOT BE MADE AT THIS TIME. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD THOUGH AHEAD OF THE COLD FRONT...WITH TEMPS RETURNING TO BELOW CLIMO FOR WEDNESDAY AS ANOTHER AREA OF HIGH PRESSURE RIDGES DOWN FROM THE NW. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... AS OF 00Z...STRONG COLD FRONT TO IMPACT THE TERMINALS TONIGHT WITH GUSTY WINDS AND A POTENTIAL SQUALL LINE WITH SHOWERS/ISOLATED THUNDERSTORMS. COLD FRONT CURRENTLY ACROSS WESTERN PORTIONS OF SC/NC WILL PUSH EAST TONIGHT AND BE ACCOMPANIED BY A LINE OF SHOWERS WITH ISOLATED THUNDERSTORMS. HRRR APPEARS TO BE INITIALIZING BETTER THAN ANY OF THE OTHER HIGH-RES GUIDANCE...SO HAVE RELIED HEAVILY ON THIS MODEL FOR TIMING CONVECTION AT THE TERMINALS...AND EXPECT THE SQUALL LINE TO IMPACT FLO/LBT AROUND 03Z...RACING EAST TO ILM AROUND 06Z. ATTM...NO IFR HAS BEEN INTRODUCED INTO THE CURRENT SET OF TAFS DUE TO UNCERTAINTY IN EXACT TIMING AND LIKELY SHORT-DURATION OF ANY PRECIP INDUCED IFR. PREFER TO HANDLE ANY IFR WITH AMD/TEMPO GROUPS AS THE CONVECTION UNFOLDS. HAVE SHOWN A 2-HR TEMPO GROUP AT ALL TERMINALS FOR THE HEAVIEST CONVECTION WITH MVFR AND INCREASED WIND GUSTS...BUT STRONGER GUSTS ARE POSSIBLE THAN WHAT IS CURRENTLY DEPICTED. OTHER CONCERN IS THE STRONG PRE-FRONTAL AND POST-FRONTAL WINDS. S/SW WINDS WILL CONTINUE TO INCREASE TONIGHT AS A STRENGTHENING LOW LEVEL JET MOVES OVERHEAD. FOR THIS REASON HAVE SHOWN INCREASING LLWS IN ALL TAFS WITH 30 KT GUSTS LIKELY THROUGH THE NIGHT...EVEN OUTSIDE OF CONVECTION. A SUDDEN WIND SHIFT WILL OCCUR WITH THE FROPA TONIGHT...AND AWWS MAY BE REQUIRED FOR ILM/MYR LATER TONIGHT AS THE FRONT CROSSES...AND WINDS SHIFT SUDDENLY TO THE WEST. RAPID DRYING OCCURS BEHIND THE FRONT AND SKC WILL BECOME THE SKY CONDITION ON THURSDAY. ALTHOUGH IT WILL BE CLEAR...STRONG WESTERLY WINDS WILL PERSIST THROUGH THE DAY...GUSTING TO 25 KTS THROUGH THE END OF THE VALID PERIOD. EXTENDED OUTLOOK...VFR THROUGH THE EXTENDED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 845 PM WEDNESDAY...SFC PG WINDS HAVE FINALLY REACHED THE COASTAL WATERS...WITH 15 TO 30 KT SUSTAINED SPEEDS WITH ASSOCIATED GUSTS FROM 25 TO 40 KT. THE HIER SPEEDS WILL OCCUR ACROSS THE OUTER WATERS OF THE ILM COASTAL WATERS...AND WHERE SSTS ARE 60 DEGREES AND HIGHER. WITH INCREASING SSE-SSW WINDS THIS AFTERNOON AND ESPECIALLY THIS EVENING...SEAS HAVE FINALLY RESPONDED. IE. SEAS AT THE OCEAN CREST PIER HAVE CLIMBED TO 6 FT AS OF THIS WRITING. OVERALL...LOOK FOR THESE WIND AND RESULTING SEA CONDITIONS TO PERSIST UNTIL THE CFP...SLATED BETWEEN 1 AM TO 4 AM WHEN THE CF TRACKS WEST TO EAST ACROSS THE ILM WATERS. OVERALL SEAS HAVE BEEN ADJUSTED UPWARDS OVERNIGHT INTO MUCH OF THE DAY ON THURSDAY. THE LATTER WAS ADJUSTED MAINLY FOR THE ILM WATERS FROM CAPE FEAR SOUTH TO MURRELLS INLET DUE TO THE STRONG WSW-W WIND DIRECTIONS KEEPING THE SEAS AGITATED. PREVIOUS DISCUSSION............................................... AS OF 300 PM WEDNESDAY...SOUTH WINDS WILL INCREASE THROUGH THE EVENING AHEAD OF A STRONG COLD FRONT NOW LOCATED FROM EASTERN TENNESSEE SOUTH TO THE FLORIDA PANHANDLE. ALTHOUGH WINDS ARE CURRENTLY ONLY 20-30 KNOTS ACROSS THE COASTAL WATERS...A 3-4 HOUR PERIOD OF MUCH STRONGER WINDS IS EXPECTED TO DEVELOP JUST AHEAD OF THE FRONT THIS EVENING. 35-40 KNOT WINDS MAY GUST MUCH HIGHER AS A NARROW LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS PUSH OFFSHORE JUST AFTER MIDNIGHT. A SEVERE THUNDERSTORM WATCH PROBABLY WILL BE NEEDED TO ADDRESS THIS POTENTIAL. BEHIND THE FRONT...WINDS WILL TURN WESTERLY IN THE 25-35 KNOT RANGE THROUGH DAYBREAK. SEAS CURRENTLY 4-7 FT WILL BUILD THIS EVENING TO 8-12 FEET AWAY FROM SHORE WITH THE STRONG SOUTH WINDS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...ALTHOUGH SEAS WILL BE ON THE DECREASE THROUGH MUCH OF THE PERIOD IN STRONG OFF SHORE FLOW...TIGHTENED GRADIENT FLOW AND COLD SURGE BEHIND FRONT THURS AND AGAIN ON FRI WILL MAINTAIN SEAS ABOVE SCA THROUGH A GOOD PORTION OF THE SHORT TERM PERIOD IN THE OUTER WATERS. WESTERLY WINDS UP AROUND 25 KTS WILL DROP THROUGH THURS ALLOWING OFF SHORE SEAS TO SUBSIDE FROM 8 TO 10 FT FRI MORNING DOWN TO 5 FT BY THURS NIGHT. WINDS WILL BACK SLIGHTLY TO THE SW THURS NIGHT INTO EARLY FRI AHEAD OF APPROACHING DRY COLD FRONT BEFORE SPIKING UP IN SURGE BEHIND FRONT. THIS WILL PRODUCE SEAS AROUND 6 FT ONCE AGAIN FOR A FEW HOURS ON FRI. THE NEAR SHORE WATERS WILL DECREASE THROUGH THURS IN OFF SHORE FLOW DOWN TO 2 TO 4 FT AND MAY SPIKE UP A BIT FRI MORNING BUT OVERALL WILL DROP OFF SOME MORE LATE FRI AS HIGH PRESSURE SHIFTS OVERHEAD ALLOWING FOR LOCAL SEAS TO DROP TO 2 TO 3 FT IN ALL WATERS. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 PM WEDNESDAY...OTHER THAN A WEAK COLD FRONT SUNDAY...DIFFUSE HIGH PRESSURE WILL DOMINATE THE WEATHER ACROSS THE WATERS THROUGH THE EXTENDED. ONE AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WATERS SATURDAY CREATING LIGHT AND VARIABLE WINDS...VEERING TO THE SW AND INCREASING TO AROUND 10 KTS LATE IN THE DAY. THIS AHEAD OF A COLD FRONT WHICH WILL CROSS DURING SUNDAY...TURNING WINDS TO THE W/NW AT 10-15 KTS ON SUNDAY BEFORE SLOWLY EASING TO LIGHT AND VARIABLE AGAIN MONDAY AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. SEAS WILL BE PRIMARILY WIND-DRIVEN THROUGH THE PERIOD...1-2 FT SATURDAY AND MONDAY...INCREASING FOR A SHORT TIME SUNDAY UP TO 2-4 FT WITH A NW WIND WAVE DOMINANT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR SCZ017-023-024-032- 033-039-053>056. NC...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR NCZ087-096-099- 105>110. MARINE...GALE WARNING UNTIL 6 AM EST THURSDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...RGZ NEAR TERM...DCH/TRA SHORT TERM...RGZ LONG TERM...JDW AVIATION...JDW
AREA FORECAST DISCUSSION
NWS ALBANY NY
415 PM EST THU JAN 31 2013 .SYNOPSIS... S A CANADIAN AIR MASS MOVES INTO THE REGION... TEMPERATURES WILL BE MUCH COLDER TONIGHT WITH A DIMINISHING WIND. LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO AFFECT THE WESTERN ADIRONDACKS AND MOHAWK VALLEY OVERNIGHT. LAKE EFFECT SNOW WILL SHIFT SOUTH AND WEST OF THE REGION TOMORROW...WITH COLD TEMPERATURES AND BREEZY CONDITIONS. SEASONABLY CHILLY TEMPERATURES WILL CONTINUE TO BE IN PLACE OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 415 PM EST...WINDS ARE STARTING TO DIMINISH AS THE PRESSURE GRADIENT BEGINS TO RELAX. THE PRESSURE COUPLET ASSOCIATED WITH THE SFC FRONTAL BOUNDARY IS WELL NORTHEAST OF THE REGION ACROSS ATLANTIC CANADA. STILL...A FEW GUSTS OF 25-40 MPH ARE OCCURRING LATE THIS AFTN...SO WE WILL LET THE CURRENT HIGH WIND WARNING EXPIRE AT 6 PM. BY THAT POINT...WINDS WILL STILL BE BREEZY FOR THE OVERNIGHT HOURS...BUT NOT ENOUGH TO CAUSE DAMAGE. A BAND OF LAKE EFFECT SNOW IS CURRENTLY ONGOING ACROSS THE WESTERN ADIRONDACKS. THE LOCAL HIRES WRF MODEL...AS WELL AS THE NAM12 AND 3KM HRRR MODEL...SHOWS THIS BAND TO SHIFT SOUTHWARD DURING THE OVERNIGHT HOURS. WITH THIS BAND HAVING AN EXCELLENT MULTI-LAKE CONNECTION ALL THE WAY BACK TO THE WESTERN GREAT LAKES AND STRONG LOW LEVEL SPEED SHEAR...LOCAL CSTAR RESEARCH WOULD SUGGEST THAT THIS BAND REACHES WELL INTO OUR AREA. AS A RESULT...HAVE ALSO INCLUDED A LAKE EFFECT SNOW ADVISORY FOR HAMILTON COUNTY...IN ADDITION TO THE WSW ALREADY IN EFFECT FOR NRN HERKIMER. SNOW TOTALS LOOK TO REACH 4-8 INCHES IN NRN HERKIMER AND 3-6 INCHES ACROSS WESTERN HAMILTON COUNTY. AS THE BAND SHIFTS SOUTH FOR LATE TONIGHT...IT SHOULD MOVE QUICKLY. WHILE A QUICK FEW INCHES OF ACCUMULATION IS POSSIBLE ACROSS THE MOHAWK VALLEY...IT SHOULD MOVE QUICK ENOUGH SOUTHWARD TO PREVENT ANY MODERATE ACCUMULATION OF SNOW. AS A RESULT...WE WILL NOT ISSUE ANY LAKE EFFECT ADVISORIES FOR THE MOHAWK VALLEY AREA...BUT WILL CONTINUE TO MENTION IN OUR HWO STATEMENT. ELSEWHERE...SOME UPSLOPE SNOW SHOWERS ARE POSSIBLE FOR THE HIGH TERRAIN OF WESTERN NEW ENGLAND WITH SOME MINOR SNOW ACCUMULATION POSSIBLE. THE REMAINDER OF THE REGION LOOKS TO BE DRY...ALTHOUGH AS THE LAKE BAND SHIFTS SOUTHWARD...THE INLAND EXTENT MAY ALLOW FOR SOME FLAKES TO REACH THE CAPITAL REGION FOR 08Z-12Z. NOT EXPECTING MUCH ACCUMULATION...BUT IT/S POSSIBLE FOR A COATING OF SNOW IN THE ALBANY/SCHENECTADY/TROY AREA BY LATE IN THE NIGHT TOWARDS DAYBREAK. MIN TEMPS WILL BE MUCH COOLER THAN LAST NIGHT. MINS WILL RANGE FROM THE SINGLE DIGITS IN THE ADKS TO THE LOW TO MID 20S IN THE MID HUDSON VALLEY. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... MAINLY DRY AND SEASONABLY COOL WEATHER IS EXPECTED THROUGH THE SHORT TERM PERIOD. THE LAKE BAND WILL SHIFT SOUTH AND WEST OF THE CWA BY FRIDAY MORNING...MAINLY ENDING THE THREAT FOR LAKE EFFECT IN OUR AREA. THE EXCEPTION MAY BE A FEW HOURS OF SNOW FOR WESTERN SCHOHARIE COUNTY WITH SOME LIGHT SNOW ACCUMULATION EARLY FRIDAY MORNING BEFORE THE BAND SHIFTS AWAY FROM THE AREA. MAX TEMPS WILL BE NOTICEABLY COOLER...WITH TEENS AND 20S ACROSS THE AREA. IN ADDITION...DAYTIME MIXING WILL ALLOW FOR SOME GUSTY WINDS...SO IT WILL FEEL EVEN COLDER...WITH SOME GUSTS OF 15-30 MPH POSSIBLE. WE WILL CONTINUE TO MENTION LOW CHC OR SLIGHT CHC POPS FOR FAR WESTERN AREAS FOR FRIDAY AFTERNOON...IN CASE UPSLOPE FLOW DOES ALLOW FOR SOME LIGHT SNOW SHOWERS...BUT ANY ADDITIONAL SNOW ACCUMULATION LOOKS LIGHT. THE HUDSON VALLEY AREA SHOULD REMAIN MAINLY DRY. CHILLY...BUT SEASONABLE TEMPS...ARE EXPECTED FRIDAY NIGHT WITH TEMPS RANGING FROM A FEW DEGREES BELOW ZERO ACROSS THE ADIRONDACKS TO THE MID TEENS IN THE HUDSON VALLEY/NW CT. A WEAK SHORTWAVE WILL PASS TO THE NORTH OF THE REGION ON SATURDAY INTO SATURDAY NIGHT. THIS MAY ALLOW FOR SOME LIGHT SNOW SHOWERS ACROSS THE ADIRONDACKS...OTHERWISE IT LOOKS CONTINUED DRY AND COOL. MAX TEMPS ON SATURDAY WILL MAINLY BE IN THE TEENS AND 20S. MIN TEMPS SAT NIGHT WILL RANGE FROM THE SINGLE DIGITS UP NORTH TO NEAR 20 SOUTH. && .LONG TERM /SUNDAY THROUGH THURSDAY/... MEAN UPPER TROUGH OVER EASTERN NORTH AMERICA THROUGH THE PERIOD... WITH LITTLE NORTHERN STREAM IMPULSES TRACKING RAPIDLY THROUGH THE CYCLONIC FLOW. THE TIMING OF THESE SYSTEMS IN SUCH QUICK UPPER FLOW IS IN QUESTION BUT TIMED THE BETTER CHANCES FOR SNOW IN THE SUNDAY TIME FRAME AND AGAIN IN THE MONDAY NIGHT TO TUESDAY TIME FRAME. THESE SYSTEMS COULD TRACK FAR ENOUGH EAST AND SOUTH OF OUR REGION THAT THERE COLD BE LITTLE TO NO SNOW IN MUCH OF THE FORECAST AREA... SO INDICATING BEST CHANCES IN THE MID HUDSON VALLEY...NW CT AND THE BERKSHIRES. ANY PRECIPITATION WOULD BE RELATIVELY LIGHT IN BOTH EVENTS...AND SHOULD NOT REQUIRE SNOW HEADLINES SINCE THE STORMS SHOULD BE STARVED FOR MOISTURE UNTIL THEY RAPIDLY HEAD OFFSHORE AND WELL EAST OF OUR REGION. OUTSIDE OF THESE POTENTIAL 2 SMALL EVENTS...SOME PERSISTENT LAKE EFFECT SNOW BANDS COULD EXTEND INTO THE SOUTHERN ADIRONDACKS... WESTERN MOHAWK VALLEY...SCHOHARIE VALLEY AND EASTERN CATSKILLS. SO...PERIODS OF CLOUDS THROUGH THE PERIOD WITH TEMPERATURES AROUND NORMAL SUNDAY...A LITTLE BELOW NORMAL MONDAY THROUGH WEDNESDAY AND BACK TO AROUND NORMAL THURSDAY. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... THE MAIN PROBLEM THIS AFTERNOON WILL BE THE CONTINUATION STRONG WINDS OUT OF THE WEST TO NORTHWEST...WHICH WILL OCCASIONALLY GUST NEAR 40 KT (OR BETTER) ESPECIALLY THIS AFTERNOON AT KALB. A HIGH WIND WARNING REMAINS IN EFFECT. THE WIND WILL ABATE SOMEWHAT TONIGHT BUT STILL CONTINUE TO OCCASIONALLY GUST 20 TO 25 KT OUT OF THE WEST TO NORTHWEST...LESS GUSTY AFTER ABOUT 02Z. CONDITIONS SHOULD REMAIN MAINLY VFR BUT CIGS COULD OCCASIONALLY DROP INTO THE HIGH MVFR RANGE AT KPSF DURING THE NIGHT. WEST TO NORTHWEST WINDS SHOULD BECOME GUSTY AGAIN TOMORROW AFTER ABOUT 16Z. IF THE CEILING AT KPSF DROPS TO MVFR TONIGHT...IT SHOULD BE BACK TO VFR AFTER 12Z. OUTLOOK... FRI-MON...MAINLY VFR. CHC SUB-VFR -SHSN. && .HYDROLOGY... SNOWMELT FROM THE RECENT WARMER TEMPERATURES AND RAINFALL FROM EARLY THIS MORNING COMBINED FOR SOME RUNOFF ACROSS THE REGION THIS MORNING. HOWEVER...THIS WAS NOT ENOUGH TO CAUSE FLOODING ACROSS OUR AREA. WITH TEMPERATURES COOLING BELOW FREEZING ACROSS THE ENTIRE AREA THIS EVENING...ANY SNOWMELT SHOULD END...AND RIVERS WILL START TO RECEDE. BECAUSE OF THE WARM TEMPERATURES AND RAINFALL...SOME ICE BROKE UP IN AREA RIVERS AND STREAMS. THIS CAUSED SOME MINOR FLOODING ON THE EAST CANADA CREEK IN DOLGEVILLE AND ALONG THE HOOSIC RIVER NEAR BUSKIRK. THE THREAT FOR ICE JAMS SHOULD DECREASE THIS EVENING WITH THE COOLER TEMPERATURES...AND ALTHOUGH ANY ICE THAT BROKE UP MAY BEGIN TO REFREEZE IN PLACE...LOWERING FLOWS SHOULD PREVENT ANY FLOODING FROM OCCURRING. THE NEXT SEVERAL DAYS WILL BE FAIRLY DRY...AND ANY LIGHT PRECIPITATION WILL BE IN THE FORM OF SNOW. THIS SHOULD ALLOW RIVERS AND STREAMS TO SLOWLY RECEDE INTO EARLY NEXT WEEK. FOR SPECIFIC RIVER AND LAKE FORECASTS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR CTZ001-013. NY...HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR NYZ032-033- 038>043-047>054-058>061-063>066-082>084. LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST FRIDAY FOR NYZ032-033. MA...HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR MAZ001-025. VT...HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR VTZ013>015. && $$ SYNOPSIS...FRUGIS NEAR TERM...FRUGIS SHORT TERM...FRUGIS LONG TERM...NAS AVIATION...NAS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
256 PM CST THU JAN 31 2013 .DISCUSSION... 1016 AM CST FOR MORNING UPDATE... HAVE MADE A FEW ADJUSTMENTS TO NEAR TERM FORECAST THIS MORNING... TO BUMP POPS A BIT FOR OCCASIONAL SNOW SHOWERS. HAVE SEEN SOME ISOLATED VISIBILITY REDUCTIONS LESS THAN A MILE AT TIMES THIS MORNING WITH A FEW PLACES PICKING UP A DUSTING TO A TENTH OF AN INCH OR SO. HAVE ALSO TOUCHED UP SKY COVER GRIDS...ACCOUNT SIGNIFICANT OPEN PATCHES THIS MORNING ACROSS WEST/SOUTH PARTS OF CWA AND CONVECTIVE NATURE OF EXPECTED CLOUD COVER THROUGH THE DAY. MORNING ANALYSIS INDICATES DEEPENING SURFACE LOW CONTINUES TO TRACK AWAY WELL TO OUR NORTHEAST ACROSS SOUTHERN QUEBEC...WITH COLD FRONT TRAILING THROUGH NORTHERN INDIANA/CENTRAL ILLINOIS. COLD ARCTIC AIR CONTINUES TO SPREAD SOUTHEAST ACROSS THE UPPER MIDWEST BEHIND THIS FRONT...WITH SINGLE DIGIT AND SUB-ZERO TEMPS WIDESPREAD TO OUR WEST/NORTHWEST. LOOKING ALOFT...RATHER STRONG MID-LEVEL SHORT WAVE WAS NOTED OVER THE EASTERN DAKOTAS/MINNESOTA...AND THIS WAVE IS PROGGED TO CONTINUE TO MOVE SOUTHEAST ACROSS OUR AREA THROUGH THIS EVENING. SCATTERED SNOW SHOWERS...SOME FAIRLY INTENSE WITH VISIBILITY REDUCTIONS AND BRIEF MINOR ACCUMULATIONS...HAVE BEEN PREVALENT ACROSS NORTHEAST IL THIS MORNING. THESE APPEAR TO BE HIGHLY DRIVEN BY STEEP LOW LEVEL LAPSE RATES AS EVIDENCED BY 12Z ILX RAOB AND RECENT AIRCRAFT AMDAR SOUNDINGS FROM ORD...WHICH DEPICT ADIABATIC LOW LEVEL PROFILES FROM THE SURFACE UP TO ABOUT 850-800 MB. THIS ALSO COINCIDES NICELY WITH THE -12 TO -18C FAVORED TEMPERATURE LAYER FOR GOOD DENDRITIC GROWTH OF ICE CRYSTALS...OF WHICH HAVE BEEN OBSERVED AT TIMES THIS MORNING. FORECAST SOUNDINGS FROM MORNING RUNS OF THE WRF-NAM AND RAP MAINTAIN THESE STEEP LOW LEVEL LAPSE RATES THROUGH THE DAY...COINCIDENT WITH BETTER MID/UPPER LEVEL FORCING ASSOCIATED WITH THE APPROACH AND PASSAGE OF AFOREMENTIONED UPPER MIDWEST SHORT WAVE. DEPSITE DRY ADVECTION OF ARCTIC AIR AND EVEN THOUGH VIS SATELLITE IMAGERY IS NOT TOO IMPRESSIVE WITH CLOUD COVER...SUSPECT THAT THIN STRATOCU WILL CONTINUE TO DEVELOP AND PERHAPS INCREASE IN COVERAGE IN UNSTABLE LOW LEVEL THERMODYNAMIC ENVIRONMENT...AND SHOULD BE ABLE TO SUSTAIN SNOW SHOWERS AND FLURRIES WITH SUFFICIENT INTENSITY AT TIMES TO PRODUCE SOME MINOR ACCUMS IN LOCALIZED AREAS. THEREFORE HAVE BUMPED POPS TO HIGHER CHANCE CATEGORY...AND WORDED OCCASIONAL SNOW SHOWERS/FLURRIES WITH A FEW TENTHS OF AN INCH POSSIBLE FOR MUCH OF NORTHERN 2/3 OR SO OF THE CWA THROUGH THE DAY...AND THIS EVENING. MID-LEVEL TROUGH AXIS MOVES ACROSS THE REGION LATE EVENING/MIDNIGHT TIME FRAME...AFTER WHICH FORECAST SOUNDINGS DEPICT STRENGTHENING/LOWERING SUBSIDENCE INVERSION WHICH SHOULD LIMIT FURTHER MEASURABLE PRECIP THREAT. OTHERWISE...GOING FORECAST LOOKS GOOD THROUGH THIS AFTERNOON WITH TEMPS NOT GOING ANYWHERE...AND COLD...BLUSTERY CONDITIONS. RATZER //PREV DISCUSSION... 340 AM CST PRIMARY FORECAST CHALLENGE THIS MORNING IS CLOUD COVER AND ITS IMPACT ON TEMPS THE NEXT SEVERAL DAYS AS WELL AS FLURRY/LIGHT SNOW CHANCES. PHASE ONE OF ARCTIC AIR HAS MOVED INTO THE AREA WITH PHASE 2 STILL UPSTREAM AND POISED TO ARRIVE THIS AFTERNOON INTO TONIGHT. AS ALLUDED TO LAST NIGHT GUIDANCE HAS BEEN FAR TOO COLD WITH TEMPS OVERNIGHT INTO THE EARLY MORNING HOURS THIS MORNING...RUNNING IN SOME CASES MORE THAN 5F TOO COLD AT 9Z THANKS TO THE CLOUD COVER AND WIND. NO APPRECIABLE CLEARING IS ANTICIPATED PRIOR TO SUNRISE SO A VERY SLOW (1-2F EVERY HOUR OR TWO) FALL SHOULD CONTINUE THROUGH SUNRISE. WITH THE RE-ENFORCING SHOT OF COLD AIR ARRIVING THIS AFTERNOON AND A GOOD DEAL OF CLOUD COVER/GUSTY NORTHWEST WINDS DONT ANTICIPATE TEMPS TO REBOUND MUCH FROM EARLY MORNING READINGS WITH TEMPS FAIRLY STEADY MOST OF THE DAY. ALONG WITH THE ARRIVAL OF THE COLD AIR...WATER VAPOR IMAGERY SHOWS A COUPLE OF VORTS UPSTREAM OVER THE NORTHERN PLAINS THAT WILL PIVOT SOUTHEAST INTO THE AREA THIS AFTERNOON/EVENING. ICE CRYSTALS ARE LIKELY ALREADY PRESENT IN THE STRATUS DECK GIVEN THE ARCTIC TEMPS SO IT WILL REMAIN REMARKABLY EASY FOR LIGHT SNOW OR FLURRIES TO FALL OUT OF THIS STRATUS DECK TODAY INTO TONIGHT...THOUGH ACCUMULATIONS SHOULD BE MINIMAL FLAKES WILL LIKELY BE FLYING AT TIMES TODAY INTO THIS EVENING. CERTAINLY THE AIR MASS ADVECTING INTO THE AREA WILL BE VERY COLD WITH EVENING SOUNDINGS UPSTREAM SAMPLING 850MB TEMPS NEAR -20C...HOWEVER ITS NOT CLEAR HOW MUCH IF ANY CLEARING WILL TAKE PLACE TONIGHT. IN THE ABSENCE OF CLEARING...THE WINDS AND CLOUDS WOULD LIKELY KEEP TEMPS SEVERAL DEGREES WARMER THAN MOS LOWS AND SUSPECT THAT CLOUDS WILL LINGER THROUGH THE NIGHT OVER EASTERN CWA WITH SOME CLEAR LATE WEST. HAVE GENERALLY ADJUSTED LOW TEMPS UPWARD SOME FROM PREVIOUS FORECAST AND GONE A BIT ABOVE THE WARMER MOS GUIDANCE NUMBERS AS MODELS SUGGEST THAT LOW LEVEL CYCLONIC FLOW WILL PERSIST MOST OF THE NIGHT RAISING SERIOUS DOUBTS ABOUT HOW MUCH CLEARING WILL TAKE PLACE. IN ADDITION...THE AIR MASS THIS GO AROUND WILL BE A COUPLE/FEW DEGREES MILDER AT 850MB THAN THE PREVIOUS ONE AND WITH LITTLE/NO SNOW COVER MOST AREAS WOULD EXPECT LOWS TO BOTTOM OUT NO COLDER THAN LAST GO AROUND AND IN ALL LIKELIHOOD A COUPLE DEGREES WARMER (WELL LESS COLD). BASED ON THE FORECAST LOWS AND EXPECTED WINDS LOOKS LIKE NC IL STANDS A REASONABLY GOOD CHANCE OF REACHING THE -20F WIND CHILL ADVISORY CRITERIA AND SO HAVE GONE AHEAD AND ISSUED THAT ALREADY THERE. FOR CHICAGO AREA AND POINTS SOUTH AND EAST IT WILL UNDOUBTEDLY BE VERY COLD TONIGHT BUT APPEARS UNLIKELY THAT THE -20F CRITERIA WILL BE MET FOR ANY LENGTH OF TIME SO KEPT ADVISORY NORTH/WEST OF THESE AREAS. COULD SEE SOME SUNSHINE THE FIRST HALF OF THE DAY ON FRIDAY BUT WILL REMAIN QUITE COLD WITH CLOUDS ROLLING BACK IN IN THE AFTERNOON AS FAST MOVING CLIPPER DIVES SE TOWARD THE AREA. VERY LITTLE CHANGE IN MODEL GUIDANCE IN HANDLING THIS WAVE WITH SWATH OF ACCUMULATING VERY FLUFFIFIED/HIGH RATION SNOW LIKELY ACROSS NORTHERN/CENTRAL ILLINOIS FRIDAY NIGHT INTO SATURDAY MORNING. DESPITE LIMITED MOISTURE...HIGH SNOW:LIQUID RATIOS COULD SUPPORT SOLID 2-3 INCH BAND OF SNOW...WITH BEST PROJECTIONS AT THIS POINT PLACING THE HEAVIEST SNOW ALONG OR SOUTH OF I-80. GIVEN HOW LOW AMPLITUDE THIS WAVE IS WOULD NOT BE A STRETCH TO ENVISION LATER RUNS REFINING THE TRACK A BIT...BUT EVEN WITH THAT IN MIND FELT FAIRLY COMFORTABLE CONTINUING THE TREND OF BUMPING POPS UP A BIT HIGHER AGAIN THIS MORNING. SEEMINGLY NEVER ENDING PARADE OF CLIPPERS ARE PROGGED TO CONTINUE TO PIVOT AROUND THE BASE OF THE TROUGH HEADING INTO NEXT WEEK. THE 00Z ECMWF HAS COME IN A BIT DEEPER AND FARTHER WEST WITH THE POLAR VORTEX OVER THE REGION WHICH WOULD PLACE OUR CWA CLOSER TO THE COLD SIDE OF THE PATH OF THESE CLIPPERS AND ALSO CLOSER TO POTENTIAL LIGHT ACCUMULATING SNOWS. THE GEM...GFS...AND PREVIOUS ECMWF WERE QUICKER TO WEAKEN THE POLAR VORTEX ALLOWING THE CLIPPERS TO PASS TO OUR NORTH KEEPING US DRY WITH ALTERNATING BOUTS OF ABOVE AVERAGE TEMPS AND SLIGHT COOL DOWNS WITH A TREND TOWARD SLIGHTLY WEAKER COOL DOWNS WITH EACH WAVE. CONFIDENCE IS NOT TERRIBLY HIGH IN ANY ONE SOLUTION AT THIS POINT BUT A TOWARD MODERATING TEMPS DEFINITELY LOOKS REASONABLE HEADING INTO NEXT WEEK WITH LESS CERTAINTY REGARDING PRECIP CHANCES. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * W WIND GUSTING 25-30 KT THROUGH THIS EVENING THEN GUSTS 15-20 KT OVERNIGHT. * PERIODS OF -SHSN THROUGH THE EARLY EVENING...HEAVIER BANDS COULD DROP VSBY DOWN TO LESS THAN A MILE. * HIGH END MVFR TO LOW END VFR CIGS EXPECTED THROUGH TONIGHT. JEE //DISCUSSION...UPDATED 18Z... AN UPPER LEVEL SHORT WAVE TROUGH MOVED THROUGH THE DAKOTAS AND PROVIDED FORCING FOR THE BANDS OF SNOW THE AREA SAW EARLIER THIS MORNING. THE SHORTWAVE IS MOVING INTO IA WITH SHSN FORMING OVER SOUTHERN WI. AS SUCH KEPT OCNL FLURRIES IN FOR THE TERMINALS THROUGH 20Z AND EXPECTING MORE SUBSTANTIAL -SHSN AFTER 20Z. THEY COULD DEVELOP A LITTLE LATER THAN INDICATED...WITH ARND A HALF INCH OF SNOW PSBL. THE HEAVIER BANDS IN WI ARE ASSOCIATED WITH VSBY OF LESS THAN 1 MILE...BUT WILL ADDRESS THOSE HEAVIER BANDS AS THEY SET UP. OVERALL THINKING VSBYS WILL BE 4SM OR BETTER. EXPECTING CIGS TO DROP A LITTLE WITH THE SNOW AS WELL TO ARND 020. A FEW UPSTREAM OBS INDICATE 015 CIGS ARE PSBL SO WILL KEEP AN EYE ON HOW THE LOWER CIGS PROGRESS. WINDS WILL REMAIN W GUSTING TO 25 KT THROUGH THE MID AFTN WITH GUSTS INCREASING TO 25-30KT THROUGH THE EVENING. WEST WINDS GUSTING 15-20 KT ARE THEN EXPECTED OVERNIGHT UNDER THE TIGHTENED PRESSURE GRADIENT. HIGH PRESSURE SINKS SOUTH TO THE EAST OF THE TERMINALS ALLOWING SKIES TO SCATTER OUT TOMORROW. JEE //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN PRECIP FCST...MEDIUM CONFIDENCE IN TIMING AND VSBY ASSOCIATED WITH -SN/-SHSN. * HIGH CONFIDENCE IN ALL OTHER FCST ELEMENTS. JEE //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... 12Z... FRIDAY NIGHT...ACCUMULATING SNOW BECOMING LIKELY. MVFR BECOMING IFR. SATURDAY...MVFR WITH A CHANCE OF IFR SNOW SHOWERS...MAINLY IN THE MORNING. SUNDAY...MVFR. MONDAY...VFR. TUESDAY...VFR. WEDNESDAY...VFR. TRS && .MARINE... 255 PM CST GUSTY WEST-NORTHWEST WINDS...ARCTIC AIR AND FREEZING SPRAY ARE THE MAIN CONCERNS IN THE NEAR TERM...WITH MARGINAL GALE FORCE WINDS EXPECTED ON THE SOUTH END OF THE LAKE OVERNIGHT. WINDS WILL GRADUALLY DIMINISH FRIDAY...THOUGH AIR TEMPS IN THE SINGLE DIGITS TO LOW TEENS WILL LIKELY CONTINUE TO RESULT IN FREEZING SPRAY EARLY IN THE DAY. HAVE EXTENDED INDIANA NEARSHORE SMALL CRAFT ADVISORY THROUGH EARLY SATURDAY MORNING...WHERE WAVES WILL BE A LITTLE SLOWER TO SUBSIDE IN PERSISTENT WEST-NORTHWEST FLOW. COLD CANADIAN HIGH PRESSURE WILL CONTINUE TO PUSH SOUTHEAST FROM THE LOWER MISSOURI VALLEY INTO THE SOUTHEASTERN U.S. FRIDAY EVENING... WITH WEAKER HIGH PRESSURE RIDGING MOVING ACROSS THE WESTERN LAKES AND ALLOWING THE GRADIENT TO RELAX AND WIND SPEEDS TO DIMINISH MORE SIGNIFICANTLY. A WEAK LOW WILL MOVE THROUGH THE MIDWEST SATURDAY... JUST SOUTH OF THE LAKES...WHICH MAKES FOR A LITTLE LOWER CONFIDENCE IN WIND DIRECTION AS THE GRADIENT REMAINS WEAK/BAGGY NEAR THE TROUGH. SPEEDS SHOULD BE BELOW 20 KTS HOWEVER. ANOTHER LOW WILL DROP SOUTHEAST ACROSS THE WESTERN/NORTHERN LAKES LATE SATURDAY NIGHT HOWEVER AND WILL BRING A RENEWED PUSH OF COLDER AIR...WHICH COMBINED WITH HIGH PRESSURE ONCE AGAIN MOVING SOUTH ACROSS THE PLAINS WILL PRODUCE A PERIOD OF GUSTY NORTHWEST WINDS OF 30-35 KTS LATE SATURDAY NIGHT THROUGH EARLY SUNDAY...HAVE MENTIONED GALES ON THE SOUTH HALF SUNDAY MORNING. FREEZING SPRAY LIKELY DURING THIS TIME AS WELL... THOUGH AIR TEMPS WILL BE A BIT WARMER THAN TONIGHT/FRIDAY MORNING. HIGH PRESSURE THEN SPREADS ACROSS THE REGION AGAIN BY SUNDAY NIGHT ALLOWING WINDS TO COME DOWN FAIRLY QUICKLY. LONGER RANGE MODEL GUIDANCE DEVELOPS ANOTHER FAIRLY WEAK LOW WHICH MOVES ACROSS THE LAKES TUESDAY...THOUGH NO DEEP STORMS THROUGH MID-WEEK. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WIND CHILL ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020...MIDNIGHT FRIDAY TO 10 AM FRIDAY. IN...NONE. LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 10 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
159 PM CST THU JAN 31 2013 .DISCUSSION... 1016 AM CST FOR MORNING UPDATE... HAVE MADE A FEW ADJUSTMENTS TO NEAR TERM FORECAST THIS MORNING... TO BUMP POPS A BIT FOR OCCASIONAL SNOW SHOWERS. HAVE SEEN SOME ISOLATED VISIBILITY REDUCTIONS LESS THAN A MILE AT TIMES THIS MORNING WITH A FEW PLACES PICKING UP A DUSTING TO A TENTH OF AN INCH OR SO. HAVE ALSO TOUCHED UP SKY COVER GRIDS...ACCOUNT SIGNIFICANT OPEN PATCHES THIS MORNING ACROSS WEST/SOUTH PARTS OF CWA AND CONVECTIVE NATURE OF EXPECTED CLOUD COVER THROUGH THE DAY. MORNING ANALYSIS INDICATES DEEPENING SURFACE LOW CONTINUES TO TRACK AWAY WELL TO OUR NORTHEAST ACROSS SOUTHERN QUEBEC...WITH COLD FRONT TRAILING THROUGH NORTHERN INDIANA/CENTRAL ILLINOIS. COLD ARCTIC AIR CONTINUES TO SPREAD SOUTHEAST ACROSS THE UPPER MIDWEST BEHIND THIS FRONT...WITH SINGLE DIGIT AND SUB-ZERO TEMPS WIDESPREAD TO OUR WEST/NORTHWEST. LOOKING ALOFT...RATHER STRONG MID-LEVEL SHORT WAVE WAS NOTED OVER THE EASTERN DAKOTAS/MINNESOTA...AND THIS WAVE IS PROGGED TO CONTINUE TO MOVE SOUTHEAST ACROSS OUR AREA THROUGH THIS EVENING. SCATTERED SNOW SHOWERS...SOME FAIRLY INTENSE WITH VISIBILITY REDUCTIONS AND BRIEF MINOR ACCUMULATIONS...HAVE BEEN PREVALENT ACROSS NORTHEAST IL THIS MORNING. THESE APPEAR TO BE HIGHLY DRIVEN BY STEEP LOW LEVEL LAPSE RATES AS EVIDENCED BY 12Z ILX RAOB AND RECENT AIRCRAFT AMDAR SOUNDINGS FROM ORD...WHICH DEPICT ADIABATIC LOW LEVEL PROFILES FROM THE SURFACE UP TO ABOUT 850-800 MB. THIS ALSO COINCIDES NICELY WITH THE -12 TO -18C FAVORED TEMPERATURE LAYER FOR GOOD DENDRITIC GROWTH OF ICE CRYSTALS...OF WHICH HAVE BEEN OBSERVED AT TIMES THIS MORNING. FORECAST SOUNDINGS FROM MORNING RUNS OF THE WRF-NAM AND RAP MAINTAIN THESE STEEP LOW LEVEL LAPSE RATES THROUGH THE DAY...COINCIDENT WITH BETTER MID/UPPER LEVEL FORCING ASSOCIATED WITH THE APPROACH AND PASSAGE OF AFOREMENTIONED UPPER MIDWEST SHORT WAVE. DEPSITE DRY ADVECTION OF ARCTIC AIR AND EVEN THOUGH VIS SATELLITE IMAGERY IS NOT TOO IMPRESSIVE WITH CLOUD COVER...SUSPECT THAT THIN STRATOCU WILL CONTINUE TO DEVELOP AND PERHAPS INCREASE IN COVERAGE IN UNSTABLE LOW LEVEL THERMODYNAMIC ENVIRONMENT...AND SHOULD BE ABLE TO SUSTAIN SNOW SHOWERS AND FLURRIES WITH SUFFICIENT INTENSITY AT TIMES TO PRODUCE SOME MINOR ACCUMS IN LOCALIZED AREAS. THEREFORE HAVE BUMPED POPS TO HIGHER CHANCE CATEGORY...AND WORDED OCCASIONAL SNOW SHOWERS/FLURRIES WITH A FEW TENTHS OF AN INCH POSSIBLE FOR MUCH OF NORTHERN 2/3 OR SO OF THE CWA THROUGH THE DAY...AND THIS EVENING. MID-LEVEL TROUGH AXIS MOVES ACROSS THE REGION LATE EVENING/MIDNIGHT TIME FRAME...AFTER WHICH FORECAST SOUNDINGS DEPICT STRENGTHENING/LOWERING SUBSIDENCE INVERSION WHICH SHOULD LIMIT FURTHER MEASURABLE PRECIP THREAT. OTHERWISE...GOING FORECAST LOOKS GOOD THROUGH THIS AFTERNOON WITH TEMPS NOT GOING ANYWHERE...AND COLD...BLUSTERY CONDITIONS. RATZER //PREV DISCUSSION... 340 AM CST PRIMARY FORECAST CHALLENGE THIS MORNING IS CLOUD COVER AND ITS IMPACT ON TEMPS THE NEXT SEVERAL DAYS AS WELL AS FLURRY/LIGHT SNOW CHANCES. PHASE ONE OF ARCTIC AIR HAS MOVED INTO THE AREA WITH PHASE 2 STILL UPSTREAM AND POISED TO ARRIVE THIS AFTERNOON INTO TONIGHT. AS ALLUDED TO LAST NIGHT GUIDANCE HAS BEEN FAR TOO COLD WITH TEMPS OVERNIGHT INTO THE EARLY MORNING HOURS THIS MORNING...RUNNING IN SOME CASES MORE THAN 5F TOO COLD AT 9Z THANKS TO THE CLOUD COVER AND WIND. NO APPRECIABLE CLEARING IS ANTICIPATED PRIOR TO SUNRISE SO A VERY SLOW (1-2F EVERY HOUR OR TWO) FALL SHOULD CONTINUE THROUGH SUNRISE. WITH THE RE-ENFORCING SHOT OF COLD AIR ARRIVING THIS AFTERNOON AND A GOOD DEAL OF CLOUD COVER/GUSTY NORTHWEST WINDS DONT ANTICIPATE TEMPS TO REBOUND MUCH FROM EARLY MORNING READINGS WITH TEMPS FAIRLY STEADY MOST OF THE DAY. ALONG WITH THE ARRIVAL OF THE COLD AIR...WATER VAPOR IMAGERY SHOWS A COUPLE OF VORTS UPSTREAM OVER THE NORTHERN PLAINS THAT WILL PIVOT SOUTHEAST INTO THE AREA THIS AFTERNOON/EVENING. ICE CRYSTALS ARE LIKELY ALREADY PRESENT IN THE STRATUS DECK GIVEN THE ARCTIC TEMPS SO IT WILL REMAIN REMARKABLY EASY FOR LIGHT SNOW OR FLURRIES TO FALL OUT OF THIS STRATUS DECK TODAY INTO TONIGHT...THOUGH ACCUMULATIONS SHOULD BE MINIMAL FLAKES WILL LIKELY BE FLYING AT TIMES TODAY INTO THIS EVENING. CERTAINLY THE AIR MASS ADVECTING INTO THE AREA WILL BE VERY COLD WITH EVENING SOUNDINGS UPSTREAM SAMPLING 850MB TEMPS NEAR -20C...HOWEVER ITS NOT CLEAR HOW MUCH IF ANY CLEARING WILL TAKE PLACE TONIGHT. IN THE ABSENCE OF CLEARING...THE WINDS AND CLOUDS WOULD LIKELY KEEP TEMPS SEVERAL DEGREES WARMER THAN MOS LOWS AND SUSPECT THAT CLOUDS WILL LINGER THROUGH THE NIGHT OVER EASTERN CWA WITH SOME CLEAR LATE WEST. HAVE GENERALLY ADJUSTED LOW TEMPS UPWARD SOME FROM PREVIOUS FORECAST AND GONE A BIT ABOVE THE WARMER MOS GUIDANCE NUMBERS AS MODELS SUGGEST THAT LOW LEVEL CYCLONIC FLOW WILL PERSIST MOST OF THE NIGHT RAISING SERIOUS DOUBTS ABOUT HOW MUCH CLEARING WILL TAKE PLACE. IN ADDITION...THE AIR MASS THIS GO AROUND WILL BE A COUPLE/FEW DEGREES MILDER AT 850MB THAN THE PREVIOUS ONE AND WITH LITTLE/NO SNOW COVER MOST AREAS WOULD EXPECT LOWS TO BOTTOM OUT NO COLDER THAN LAST GO AROUND AND IN ALL LIKELIHOOD A COUPLE DEGREES WARMER (WELL LESS COLD). BASED ON THE FORECAST LOWS AND EXPECTED WINDS LOOKS LIKE NC IL STANDS A REASONABLY GOOD CHANCE OF REACHING THE -20F WIND CHILL ADVISORY CRITERIA AND SO HAVE GONE AHEAD AND ISSUED THAT ALREADY THERE. FOR CHICAGO AREA AND POINTS SOUTH AND EAST IT WILL UNDOUBTEDLY BE VERY COLD TONIGHT BUT APPEARS UNLIKELY THAT THE -20F CRITERIA WILL BE MET FOR ANY LENGTH OF TIME SO KEPT ADVISORY NORTH/WEST OF THESE AREAS. COULD SEE SOME SUNSHINE THE FIRST HALF OF THE DAY ON FRIDAY BUT WILL REMAIN QUITE COLD WITH CLOUDS ROLLING BACK IN IN THE AFTERNOON AS FAST MOVING CLIPPER DIVES SE TOWARD THE AREA. VERY LITTLE CHANGE IN MODEL GUIDANCE IN HANDLING THIS WAVE WITH SWATH OF ACCUMULATING VERY FLUFFIFIED/HIGH RATION SNOW LIKELY ACROSS NORTHERN/CENTRAL ILLINOIS FRIDAY NIGHT INTO SATURDAY MORNING. DESPITE LIMITED MOISTURE...HIGH SNOW:LIQUID RATIOS COULD SUPPORT SOLID 2-3 INCH BAND OF SNOW...WITH BEST PROJECTIONS AT THIS POINT PLACING THE HEAVIEST SNOW ALONG OR SOUTH OF I-80. GIVEN HOW LOW AMPLITUDE THIS WAVE IS WOULD NOT BE A STRETCH TO ENVISION LATER RUNS REFINING THE TRACK A BIT...BUT EVEN WITH THAT IN MIND FELT FAIRLY COMFORTABLE CONTINUING THE TREND OF BUMPING POPS UP A BIT HIGHER AGAIN THIS MORNING. SEEMINGLY NEVER ENDING PARADE OF CLIPPERS ARE PROGGED TO CONTINUE TO PIVOT AROUND THE BASE OF THE TROUGH HEADING INTO NEXT WEEK. THE 00Z ECMWF HAS COME IN A BIT DEEPER AND FARTHER WEST WITH THE POLAR VORTEX OVER THE REGION WHICH WOULD PLACE OUR CWA CLOSER TO THE COLD SIDE OF THE PATH OF THESE CLIPPERS AND ALSO CLOSER TO POTENTIAL LIGHT ACCUMULATING SNOWS. THE GEM...GFS...AND PREVIOUS ECMWF WERE QUICKER TO WEAKEN THE POLAR VORTEX ALLOWING THE CLIPPERS TO PASS TO OUR NORTH KEEPING US DRY WITH ALTERNATING BOUTS OF ABOVE AVERAGE TEMPS AND SLIGHT COOL DOWNS WITH A TREND TOWARD SLIGHTLY WEAKER COOL DOWNS WITH EACH WAVE. CONFIDENCE IS NOT TERRIBLY HIGH IN ANY ONE SOLUTION AT THIS POINT BUT A TOWARD MODERATING TEMPS DEFINITELY LOOKS REASONABLE HEADING INTO NEXT WEEK WITH LESS CERTAINTY REGARDING PRECIP CHANCES. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * W WIND GUSTING 25-30 KT THROUGH THIS EVENING THEN GUSTS 15-20 KT OVERNIGHT. * PERIODS OF -SHSN THROUGH THE EARLY EVENING...HEAVIER BANDS COULD DROP VSBY DOWN TO LESS THAN A MILE. * HIGH END MVFR TO LOW END VFR CIGS EXPECTED THROUGH TONIGHT. JEE //DISCUSSION...UPDATED 18Z... AN UPPER LEVEL SHORT WAVE TROUGH MOVED THROUGH THE DAKOTAS AND PROVIDED FORCING FOR THE BANDS OF SNOW THE AREA SAW EARLIER THIS MORNING. THE SHORTWAVE IS MOVING INTO IA WITH SHSN FORMING OVER SOUTHERN WI. AS SUCH KEPT OCNL FLURRIES IN FOR THE TERMINALS THROUGH 20Z AND EXPECTING MORE SUBSTANTIAL -SHSN AFTER 20Z. THEY COULD DEVELOP A LITTLE LATER THAN INDICATED...WITH ARND A HALF INCH OF SNOW PSBL. THE HEAVIER BANDS IN WI ARE ASSOCIATED WITH VSBY OF LESS THAN 1 MILE...BUT WILL ADDRESS THOSE HEAVIER BANDS AS THEY SET UP. OVERALL THINKING VSBYS WILL BE 4SM OR BETTER. EXPECTING CIGS TO DROP A LITTLE WITH THE SNOW AS WELL TO ARND 020. A FEW UPSTREAM OBS INDICATE 015 CIGS ARE PSBL SO WILL KEEP AN EYE ON HOW THE LOWER CIGS PROGRESS. WINDS WILL REMAIN W GUSTING TO 25 KT THROUGH THE MID AFTN WITH GUSTS INCREASING TO 25-30KT THROUGH THE EVENING. WEST WINDS GUSTING 15-20 KT ARE THEN EXPECTED OVERNIGHT UNDER THE TIGHTENED PRESSURE GRADIENT. HIGH PRESSURE SINKS SOUTH TO THE EAST OF THE TERMINALS ALLOWING SKIES TO SCATTER OUT TOMORROW. JEE //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN PRECIP FCST...MEDIUM CONFIDENCE IN TIMING AND VSBY ASSOCIATED WITH -SN/-SHSN. * HIGH CONFIDENCE IN ALL OTHER FCST ELEMENTS. JEE //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... 12Z... FRIDAY NIGHT...ACCUMULATING SNOW BECOMING LIKELY. MVFR BECOMING IFR. SATURDAY...MVFR WITH A CHANCE OF IFR SNOW SHOWERS...MAINLY IN THE MORNING. SUNDAY...MVFR. MONDAY...VFR. TUESDAY...VFR. WEDNESDAY...VFR. TRS && .MARINE... 446 AM CST DEEP LOW PRESSURE HAS MOVED FROM GEORGIAN BAY INTO SW QUEBEC DURING LATE WED EVENING AND EARLY THIS MORNING AND WILL CONTINUE TO MOVE FURTHER OFF TO THE NE. W TO WNW WINDS HAVE SLACKENED A BIT AS A RESULT OR THE DECREASING PRESSURE GRADIENT OVER LAKE MI THOUGH A FEW COASTAL OBSERVATION SITES ALONG THE IN AND FAR SW LOWER MI SHORED CONTINUED TO MEASURE SOME 35-40KT GALE FORCE GUSTS. WINDS WILL CONTINUE TO GRADUALLY DIMINISH DURING THE PREDAWN AND EARLY MORNING HOURS BUT WILL REMAIN BRISK AS STRONG HIGH PRESSURE CONTINUES TO BUILD SE FROM SOUTHERN SASKATCHEWAN ACROSS THE NORTHERN AND CENTRAL PLAINS TODAY. WINDS WILL INCREASE AND REACH GALES ON THE SOUTH PORTION OF THE LAKE BY MID AFTERNOON AS A SURFACE TROUGH DROPS SE DOWN THE LAKE SPREADING AND ANOTHER SURGE OF COLD AIR OVER THE REGION. GALE FORCE WINDS AND VERY COLD AIR WILL RESULT IN FREEZING SPRAY ACROSS THE LAKE. GALES WILL CONTINUE INTO LATE TONIGHT. BY FRIDAY MORNING A LARGE AREA OF HIGH PRESSURE WILL BE CENTERED OVER IA AND MO. THE PRESSURE GRADIENT DECREASES AS THE CENTER OF THE HIGH MOVES NEARER TO THE AREA AND WINDS ON THE LAKE WILL DIMINISH TO BELOW GALE FORCE BY FRI MORNING. NW WINDS GRADUALLY BACK TO SW DURING FRI AS THE CENTER OF THE HIGH MOVES TO KY AND TN BY LATE IN THE AFTERNOON. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WIND CHILL ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010- ILZ011...MIDNIGHT FRIDAY TO 10 AM FRIDAY. IN...NONE. LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 10 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1125 AM CST THU JAN 31 2013 .DISCUSSION... 1016 AM CST FOR MORNING UPDATE... HAVE MADE A FEW ADJUSTMENTS TO NEAR TERM FORECAST THIS MORNING... TO BUMP POPS A BIT FOR OCCASIONAL SNOW SHOWERS. HAVE SEEN SOME ISOLATED VISIBILITY REDUCTIONS LESS THAN A MILE AT TIMES THIS MORNING WITH A FEW PLACES PICKING UP A DUSTING TO A TENTH OF AN INCH OR SO. HAVE ALSO TOUCHED UP SKY COVER GRIDS...ACCOUNT SIGNIFICANT OPEN PATCHES THIS MORNING ACROSS WEST/SOUTH PARTS OF CWA AND CONVECTIVE NATURE OF EXPECTED CLOUD COVER THROUGH THE DAY. MORNING ANALYSIS INDICATES DEEPENING SURFACE LOW CONTINUES TO TRACK AWAY WELL TO OUR NORTHEAST ACROSS SOUTHERN QUEBEC...WITH COLD FRONT TRAILING THROUGH NORTHERN INDIANA/CENTRAL ILLINOIS. COLD ARCTIC AIR CONTINUES TO SPREAD SOUTHEAST ACROSS THE UPPER MIDWEST BEHIND THIS FRONT...WITH SINGLE DIGIT AND SUB-ZERO TEMPS WIDESPREAD TO OUR WEST/NORTHWEST. LOOKING ALOFT...RATHER STRONG MID-LEVEL SHORT WAVE WAS NOTED OVER THE EASTERN DAKOTAS/MINNESOTA...AND THIS WAVE IS PROGGED TO CONTINUE TO MOVE SOUTHEAST ACROSS OUR AREA THROUGH THIS EVENING. SCATTERED SNOW SHOWERS...SOME FAIRLY INTENSE WITH VISIBILITY REDUCTIONS AND BRIEF MINOR ACCUMULATIONS...HAVE BEEN PREVALENT ACROSS NORTHEAST IL THIS MORNING. THESE APPEAR TO BE HIGHLY DRIVEN BY STEEP LOW LEVEL LAPSE RATES AS EVIDENCED BY 12Z ILX RAOB AND RECENT AIRCRAFT AMDAR SOUNDINGS FROM ORD...WHICH DEPICT ADIABATIC LOW LEVEL PROFILES FROM THE SURFACE UP TO ABOUT 850-800 MB. THIS ALSO COINCIDES NICELY WITH THE -12 TO -18C FAVORED TEMPERATURE LAYER FOR GOOD DENDRITIC GROWTH OF ICE CRYSTALS...OF WHICH HAVE BEEN OBSERVED AT TIMES THIS MORNING. FORECAST SOUNDINGS FROM MORNING RUNS OF THE WRF-NAM AND RAP MAINTAIN THESE STEEP LOW LEVEL LAPSE RATES THROUGH THE DAY...COINCIDENT WITH BETTER MID/UPPER LEVEL FORCING ASSOCIATED WITH THE APPROACH AND PASSAGE OF AFOREMENTIONED UPPER MIDWEST SHORT WAVE. DEPSITE DRY ADVECTION OF ARCTIC AIR AND EVEN THOUGH VIS SATELLITE IMAGERY IS NOT TOO IMPRESSIVE WITH CLOUD COVER...SUSPECT THAT THIN STRATOCU WILL CONTINUE TO DEVELOP AND PERHAPS INCREASE IN COVERAGE IN UNSTABLE LOW LEVEL THERMODYNAMIC ENVIRONMENT...AND SHOULD BE ABLE TO SUSTAIN SNOW SHOWERS AND FLURRIES WITH SUFFICIENT INTENSITY AT TIMES TO PRODUCE SOME MINOR ACCUMS IN LOCALIZED AREAS. THEREFORE HAVE BUMPED POPS TO HIGHER CHANCE CATEGORY...AND WORDED OCCASIONAL SNOW SHOWERS/FLURRIES WITH A FEW TENTHS OF AN INCH POSSIBLE FOR MUCH OF NORTHERN 2/3 OR SO OF THE CWA THROUGH THE DAY...AND THIS EVENING. MID-LEVEL TROUGH AXIS MOVES ACROSS THE REGION LATE EVENING/MIDNIGHT TIME FRAME...AFTER WHICH FORECAST SOUNDINGS DEPICT STRENGTHENING/LOWERING SUBSIDENCE INVERSION WHICH SHOULD LIMIT FURTHER MEASURABLE PRECIP THREAT. OTHERWISE...GOING FORECAST LOOKS GOOD THROUGH THIS AFTERNOON WITH TEMPS NOT GOING ANYWHERE...AND COLD...BLUSTERY CONDITIONS. RATZER //PREV DISCUSSION... 340 AM CST PRIMARY FORECAST CHALLENGE THIS MORNING IS CLOUD COVER AND ITS IMPACT ON TEMPS THE NEXT SEVERAL DAYS AS WELL AS FLURRY/LIGHT SNOW CHANCES. PHASE ONE OF ARCTIC AIR HAS MOVED INTO THE AREA WITH PHASE 2 STILL UPSTREAM AND POISED TO ARRIVE THIS AFTERNOON INTO TONIGHT. AS ALLUDED TO LAST NIGHT GUIDANCE HAS BEEN FAR TOO COLD WITH TEMPS OVERNIGHT INTO THE EARLY MORNING HOURS THIS MORNING...RUNNING IN SOME CASES MORE THAN 5F TOO COLD AT 9Z THANKS TO THE CLOUD COVER AND WIND. NO APPRECIABLE CLEARING IS ANTICIPATED PRIOR TO SUNRISE SO A VERY SLOW (1-2F EVERY HOUR OR TWO) FALL SHOULD CONTINUE THROUGH SUNRISE. WITH THE RE-ENFORCING SHOT OF COLD AIR ARRIVING THIS AFTERNOON AND A GOOD DEAL OF CLOUD COVER/GUSTY NORTHWEST WINDS DONT ANTICIPATE TEMPS TO REBOUND MUCH FROM EARLY MORNING READINGS WITH TEMPS FAIRLY STEADY MOST OF THE DAY. ALONG WITH THE ARRIVAL OF THE COLD AIR...WATER VAPOR IMAGERY SHOWS A COUPLE OF VORTS UPSTREAM OVER THE NORTHERN PLAINS THAT WILL PIVOT SOUTHEAST INTO THE AREA THIS AFTERNOON/EVENING. ICE CRYSTALS ARE LIKELY ALREADY PRESENT IN THE STRATUS DECK GIVEN THE ARCTIC TEMPS SO IT WILL REMAIN REMARKABLY EASY FOR LIGHT SNOW OR FLURRIES TO FALL OUT OF THIS STRATUS DECK TODAY INTO TONIGHT...THOUGH ACCUMULATIONS SHOULD BE MINIMAL FLAKES WILL LIKELY BE FLYING AT TIMES TODAY INTO THIS EVENING. CERTAINLY THE AIR MASS ADVECTING INTO THE AREA WILL BE VERY COLD WITH EVENING SOUNDINGS UPSTREAM SAMPLING 850MB TEMPS NEAR -20C...HOWEVER ITS NOT CLEAR HOW MUCH IF ANY CLEARING WILL TAKE PLACE TONIGHT. IN THE ABSENCE OF CLEARING...THE WINDS AND CLOUDS WOULD LIKELY KEEP TEMPS SEVERAL DEGREES WARMER THAN MOS LOWS AND SUSPECT THAT CLOUDS WILL LINGER THROUGH THE NIGHT OVER EASTERN CWA WITH SOME CLEAR LATE WEST. HAVE GENERALLY ADJUSTED LOW TEMPS UPWARD SOME FROM PREVIOUS FORECAST AND GONE A BIT ABOVE THE WARMER MOS GUIDANCE NUMBERS AS MODELS SUGGEST THAT LOW LEVEL CYCLONIC FLOW WILL PERSIST MOST OF THE NIGHT RAISING SERIOUS DOUBTS ABOUT HOW MUCH CLEARING WILL TAKE PLACE. IN ADDITION...THE AIR MASS THIS GO AROUND WILL BE A COUPLE/FEW DEGREES MILDER AT 850MB THAN THE PREVIOUS ONE AND WITH LITTLE/NO SNOW COVER MOST AREAS WOULD EXPECT LOWS TO BOTTOM OUT NO COLDER THAN LAST GO AROUND AND IN ALL LIKELIHOOD A COUPLE DEGREES WARMER (WELL LESS COLD). BASED ON THE FORECAST LOWS AND EXPECTED WINDS LOOKS LIKE NC IL STANDS A REASONABLY GOOD CHANCE OF REACHING THE -20F WIND CHILL ADVISORY CRITERIA AND SO HAVE GONE AHEAD AND ISSUED THAT ALREADY THERE. FOR CHICAGO AREA AND POINTS SOUTH AND EAST IT WILL UNDOUBTEDLY BE VERY COLD TONIGHT BUT APPEARS UNLIKELY THAT THE -20F CRITERIA WILL BE MET FOR ANY LENGTH OF TIME SO KEPT ADVISORY NORTH/WEST OF THESE AREAS. COULD SEE SOME SUNSHINE THE FIRST HALF OF THE DAY ON FRIDAY BUT WILL REMAIN QUITE COLD WITH CLOUDS ROLLING BACK IN IN THE AFTERNOON AS FAST MOVING CLIPPER DIVES SE TOWARD THE AREA. VERY LITTLE CHANGE IN MODEL GUIDANCE IN HANDLING THIS WAVE WITH SWATH OF ACCUMULATING VERY FLUFFIFIED/HIGH RATION SNOW LIKELY ACROSS NORTHERN/CENTRAL ILLINOIS FRIDAY NIGHT INTO SATURDAY MORNING. DESPITE LIMITED MOISTURE...HIGH SNOW:LIQUID RATIOS COULD SUPPORT SOLID 2-3 INCH BAND OF SNOW...WITH BEST PROJECTIONS AT THIS POINT PLACING THE HEAVIEST SNOW ALONG OR SOUTH OF I-80. GIVEN HOW LOW AMPLITUDE THIS WAVE IS WOULD NOT BE A STRETCH TO ENVISION LATER RUNS REFINING THE TRACK A BIT...BUT EVEN WITH THAT IN MIND FELT FAIRLY COMFORTABLE CONTINUING THE TREND OF BUMPING POPS UP A BIT HIGHER AGAIN THIS MORNING. SEEMINGLY NEVER ENDING PARADE OF CLIPPERS ARE PROGGED TO CONTINUE TO PIVOT AROUND THE BASE OF THE TROUGH HEADING INTO NEXT WEEK. THE 00Z ECMWF HAS COME IN A BIT DEEPER AND FARTHER WEST WITH THE POLAR VORTEX OVER THE REGION WHICH WOULD PLACE OUR CWA CLOSER TO THE COLD SIDE OF THE PATH OF THESE CLIPPERS AND ALSO CLOSER TO POTENTIAL LIGHT ACCUMULATING SNOWS. THE GEM...GFS...AND PREVIOUS ECMWF WERE QUICKER TO WEAKEN THE POLAR VORTEX ALLOWING THE CLIPPERS TO PASS TO OUR NORTH KEEPING US DRY WITH ALTERNATING BOUTS OF ABOVE AVERAGE TEMPS AND SLIGHT COOL DOWNS WITH A TREND TOWARD SLIGHTLY WEAKER COOL DOWNS WITH EACH WAVE. CONFIDENCE IS NOT TERRIBLY HIGH IN ANY ONE SOLUTION AT THIS POINT BUT A TOWARD MODERATING TEMPS DEFINITELY LOOKS REASONABLE HEADING INTO NEXT WEEK WITH LESS CERTAINTY REGARDING PRECIP CHANCES. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * W WIND GUSTING 20-25KT THROUGH EARLY AFTERNOON...THEN GUSTING 25-30KT LATE AFTN AND THROUGH THE EVENING. * SCATTERED -SN/FLURRIES PASSING OVER THE TERMINALS THROUGH 20Z THEN A PERIOD OF -SHSN LATE THIS AFTN/EARLY EVENING. * HIGH END MVFR TO LOW END VFR CIGS EXPECTED THROUGH TONIGHT. JEE //DISCUSSION...UPDATED 18Z... AN UPPER LEVEL SHORT WAVE TROUGH MOVED THROUGH THE DAKOTAS AND PROVIDED FORCING FOR THE BANDS OF SNOW THE AREA SAW EARLIER THIS MORNING. THE SHORTWAVE IS MOVING INTO IA WITH SHSN FORMING OVER SOUTHERN WI. AS SUCH KEPT OCNL FLURRIES IN FOR THE TERMINALS THROUGH 20Z AND EXPECTING MORE SUBSTANTIAL -SHSN AFTER 20Z. THEY COULD DEVELOP A LITTLE LATER THAN INDICATED...WITH ARND A HALF INCH OF SNOW PSBL. THE HEAVIER BANDS IN WI ARE ASSOCIATED WITH VSBY OF LESS THAN 1 MILE...BUT WILL ADDRESS THOSE HEAVIER BANDS AS THEY SET UP. OVERALL THINKING VSBYS WILL BE 4SM OR BETTER. EXPECTING CIGS TO DROP A LITTLE WITH THE SNOW AS WELL TO ARND 020. A FEW UPSTREAM OBS INDICATE 015 CIGS ARE PSBL SO WILL KEEP AN EYE ON HOW THE LOWER CIGS PROGRESS. WINDS WILL REMAIN W GUSTING TO 25 KT THROUGH THE MID AFTN WITH GUSTS INCREASING TO 25-30KT THROUGH THE EVENING. WEST WINDS GUSTING 15-20 KT ARE THEN EXPECTED OVERNIGHT UNDER THE TIGHTENED PRESSURE GRADIENT. HIGH PRESSURE SINKS SOUTH TO THE EAST OF THE TERMINALS ALLOWING SKIES TO SCATTER OUT TOMORROW. JEE //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN PRECIP FCST...MEDIUM CONFIDENCE IN TIMING AND VSBY ASSOCIATED WITH -SN/-SHSN. * HIGH CONFIDENCE IN ALL OTHER FCST ELEMENTS. JEE //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... 12Z... FRIDAY NIGHT...ACCUMULATING SNOW BECOMING LIKELY. MVFR BECOMING IFR. SATURDAY...MVFR WITH A CHANCE OF IFR SNOW SHOWERS...MAINLY IN THE MORNING. SUNDAY...MVFR. MONDAY...VFR. TUESDAY...VFR. WEDNESDAY...VFR. TRS && .MARINE... 446 AM CST DEEP LOW PRESSURE HAS MOVED FROM GEORGIAN BAY INTO SW QUEBEC DURING LATE WED EVENING AND EARLY THIS MORNING AND WILL CONTINUE TO MOVE FURTHER OFF TO THE NE. W TO WNW WINDS HAVE SLACKENED A BIT AS A RESULT OR THE DECREASING PRESSURE GRADIENT OVER LAKE MI THOUGH A FEW COASTAL OBSERVATION SITES ALONG THE IN AND FAR SW LOWER MI SHORED CONTINUED TO MEASURE SOME 35-40KT GALE FORCE GUSTS. WINDS WILL CONTINUE TO GRADUALLY DIMINISH DURING THE PREDAWN AND EARLY MORNING HOURS BUT WILL REMAIN BRISK AS STRONG HIGH PRESSURE CONTINUES TO BUILD SE FROM SOUTHERN SASKATCHEWAN ACROSS THE NORTHERN AND CENTRAL PLAINS TODAY. WINDS WILL INCREASE AND REACH GALES ON THE SOUTH PORTION OF THE LAKE BY MID AFTERNOON AS A SURFACE TROUGH DROPS SE DOWN THE LAKE SPREADING AND ANOTHER SURGE OF COLD AIR OVER THE REGION. GALE FORCE WINDS AND VERY COLD AIR WILL RESULT IN FREEZING SPRAY ACROSS THE LAKE. GALES WILL CONTINUE INTO LATE TONIGHT. BY FRIDAY MORNING A LARGE AREA OF HIGH PRESSURE WILL BE CENTERED OVER IA AND MO. THE PRESSURE GRADIENT DECREASES AS THE CENTER OF THE HIGH MOVES NEARER TO THE AREA AND WINDS ON THE LAKE WILL DIMINISH TO BELOW GALE FORCE BY FRI MORNING. NW WINDS GRADUALLY BACK TO SW DURING FRI AS THE CENTER OF THE HIGH MOVES TO KY AND TN BY LATE IN THE AFTERNOON. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WIND CHILL ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010- ILZ011...MIDNIGHT FRIDAY TO 10 AM FRIDAY. IN...NONE. LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 PM THURSDAY TO 6 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 10 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 PM FRIDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1017 AM CST THU JAN 31 2013 .DISCUSSION... 1016 AM CST FOR MORNING UPDATE... HAVE MADE A FEW ADJUSTMENTS TO NEAR TERM FORECAST THIS MORNING... TO BUMP POPS A BIT FOR OCCASIONAL SNOW SHOWERS. HAVE SEEN SOME ISOLATED VISIBILITY REDUCTIONS LESS THAN A MILE AT TIMES THIS MORNING WITH A FEW PLACES PICKING UP A DUSTING TO A TENTH OF AN INCH OR SO. HAVE ALSO TOUCHED UP SKY COVER GRIDS...ACCOUNT SIGNIFICANT OPEN PATCHES THIS MORNING ACROSS WEST/SOUTH PARTS OF CWA AND CONVECTIVE NATURE OF EXPECTED CLOUD COVER THROUGH THE DAY. MORNING ANALYSIS INDICATES DEEPENING SURFACE LOW CONTINUES TO TRACK AWAY WELL TO OUR NORTHEAST ACROSS SOUTHERN QUEBEC...WITH COLD FRONT TRAILING THROUGH NORTHERN INDIANA/CENTRAL ILLINOIS. COLD ARCTIC AIR CONTINUES TO SPREAD SOUTHEAST ACROSS THE UPPER MIDWEST BEHIND THIS FRONT...WITH SINGLE DIGIT AND SUB-ZERO TEMPS WIDESPREAD TO OUR WEST/NORTHWEST. LOOKING ALOFT...RATHER STRONG MID-LEVEL SHORT WAVE WAS NOTED OVER THE EASTERN DAKOTAS/MINNESOTA...AND THIS WAVE IS PROGGED TO CONTINUE TO MOVE SOUTHEAST ACROSS OUR AREA THROUGH THIS EVENING. SCATTERED SNOW SHOWERS...SOME FAIRLY INTENSE WITH VISIBILITY REDUCTIONS AND BRIEF MINOR ACCUMULATIONS...HAVE BEEN PREVALENT ACROSS NORTHEAST IL THIS MORNING. THESE APPEAR TO BE HIGHLY DRIVEN BY STEEP LOW LEVEL LAPSE RATES AS EVIDENCED BY 12Z ILX RAOB AND RECENT AIRCRAFT AMDAR SOUNDINGS FROM ORD...WHICH DEPICT ADIABATIC LOW LEVEL PROFILES FROM THE SURFACE UP TO ABOUT 850-800 MB. THIS ALSO COINCIDES NICELY WITH THE -12 TO -18C FAVORED TEMPERATURE LAYER FOR GOOD DENDRITIC GROWTH OF ICE CRYSTALS...OF WHICH HAVE BEEN OBSERVED AT TIMES THIS MORNING. FORECAST SOUNDINGS FROM MORNING RUNS OF THE WRF-NAM AND RAP MAINTAIN THESE STEEP LOW LEVEL LAPSE RATES THROUGH THE DAY...COINCIDENT WITH BETTER MID/UPPER LEVEL FORCING ASSOCIATED WITH THE APPROACH AND PASSAGE OF AFOREMENTIONED UPPER MIDWEST SHORT WAVE. DEPSITE DRY ADVECTION OF ARCTIC AIR AND EVEN THOUGH VIS SATELLITE IMAGERY IS NOT TOO IMPRESSIVE WITH CLOUD COVER...SUSPECT THAT THIN STRATOCU WILL CONTINUE TO DEVELOP AND PERHAPS INCREASE IN COVERAGE IN UNSTABLE LOW LEVEL THERMODYNAMIC ENVIRONMENT...AND SHOULD BE ABLE TO SUSTAIN SNOW SHOWERS AND FLURRIES WITH SUFFICIENT INTENSITY AT TIMES TO PRODUCE SOME MINOR ACCUMS IN LOCALIZED AREAS. THEREFORE HAVE BUMPED POPS TO HIGHER CHANCE CATEGORY...AND WORDED OCCASIONAL SNOW SHOWERS/FLURRIES WITH A FEW TENTHS OF AN INCH POSSIBLE FOR MUCH OF NORTHERN 2/3 OR SO OF THE CWA THROUGH THE DAY...AND THIS EVENING. MID-LEVEL TROUGH AXIS MOVES ACROSS THE REGION LATE EVENING/MIDNIGHT TIME FRAME...AFTER WHICH FORECAST SOUNDINGS DEPICT STRENGTHENING/LOWERING SUBSIDENCE INVERSION WHICH SHOULD LIMIT FURTHER MEASURABLE PRECIP THREAT. OTHERWISE...GOING FORECAST LOOKS GOOD THROUGH THIS AFTERNOON WITH TEMPS NOT GOING ANYWHERE...AND COLD...BLUSTERY CONDITIONS. RATZER && .PREV DISCUSSION... 340 AM CST PRIMARY FORECAST CHALLENGE THIS MORNING IS CLOUD COVER AND ITS IMPACT ON TEMPS THE NEXT SEVERAL DAYS AS WELL AS FLURRY/LIGHT SNOW CHANCES. PHASE ONE OF ARCTIC AIR HAS MOVED INTO THE AREA WITH PHASE 2 STILL UPSTREAM AND POISED TO ARRIVE THIS AFTERNOON INTO TONIGHT. AS ALLUDED TO LAST NIGHT GUIDANCE HAS BEEN FAR TOO COLD WITH TEMPS OVERNIGHT INTO THE EARLY MORNING HOURS THIS MORNING...RUNNING IN SOME CASES MORE THAN 5F TOO COLD AT 9Z THANKS TO THE CLOUD COVER AND WIND. NO APPRECIABLE CLEARING IS ANTICIPATED PRIOR TO SUNRISE SO A VERY SLOW (1-2F EVERY HOUR OR TWO) FALL SHOULD CONTINUE THROUGH SUNRISE. WITH THE RE-ENFORCING SHOT OF COLD AIR ARRIVING THIS AFTERNOON AND A GOOD DEAL OF CLOUD COVER/GUSTY NORTHWEST WINDS DONT ANTICIPATE TEMPS TO REBOUND MUCH FROM EARLY MORNING READINGS WITH TEMPS FAIRLY STEADY MOST OF THE DAY. ALONG WITH THE ARRIVAL OF THE COLD AIR...WATER VAPOR IMAGERY SHOWS A COUPLE OF VORTS UPSTREAM OVER THE NORTHERN PLAINS THAT WILL PIVOT SOUTHEAST INTO THE AREA THIS AFTERNOON/EVENING. ICE CRYSTALS ARE LIKELY ALREADY PRESENT IN THE STRATUS DECK GIVEN THE ARCTIC TEMPS SO IT WILL REMAIN REMARKABLY EASY FOR LIGHT SNOW OR FLURRIES TO FALL OUT OF THIS STRATUS DECK TODAY INTO TONIGHT...THOUGH ACCUMULATIONS SHOULD BE MINIMAL FLAKES WILL LIKELY BE FLYING AT TIMES TODAY INTO THIS EVENING. CERTAINLY THE AIR MASS ADVECTING INTO THE AREA WILL BE VERY COLD WITH EVENING SOUNDINGS UPSTREAM SAMPLING 850MB TEMPS NEAR -20C...HOWEVER ITS NOT CLEAR HOW MUCH IF ANY CLEARING WILL TAKE PLACE TONIGHT. IN THE ABSENCE OF CLEARING...THE WINDS AND CLOUDS WOULD LIKELY KEEP TEMPS SEVERAL DEGREES WARMER THAN MOS LOWS AND SUSPECT THAT CLOUDS WILL LINGER THROUGH THE NIGHT OVER EASTERN CWA WITH SOME CLEAR LATE WEST. HAVE GENERALLY ADJUSTED LOW TEMPS UPWARD SOME FROM PREVIOUS FORECAST AND GONE A BIT ABOVE THE WARMER MOS GUIDANCE NUMBERS AS MODELS SUGGEST THAT LOW LEVEL CYCLONIC FLOW WILL PERSIST MOST OF THE NIGHT RAISING SERIOUS DOUBTS ABOUT HOW MUCH CLEARING WILL TAKE PLACE. IN ADDITION...THE AIR MASS THIS GO AROUND WILL BE A COUPLE/FEW DEGREES MILDER AT 850MB THAN THE PREVIOUS ONE AND WITH LITTLE/NO SNOW COVER MOST AREAS WOULD EXPECT LOWS TO BOTTOM OUT NO COLDER THAN LAST GO AROUND AND IN ALL LIKELIHOOD A COUPLE DEGREES WARMER (WELL LESS COLD). BASED ON THE FORECAST LOWS AND EXPECTED WINDS LOOKS LIKE NC IL STANDS A REASONABLY GOOD CHANCE OF REACHING THE -20F WIND CHILL ADVISORY CRITERIA AND SO HAVE GONE AHEAD AND ISSUED THAT ALREADY THERE. FOR CHICAGO AREA AND POINTS SOUTH AND EAST IT WILL UNDOUBTEDLY BE VERY COLD TONIGHT BUT APPEARS UNLIKELY THAT THE -20F CRITERIA WILL BE MET FOR ANY LENGTH OF TIME SO KEPT ADVISORY NORTH/WEST OF THESE AREAS. COULD SEE SOME SUNSHINE THE FIRST HALF OF THE DAY ON FRIDAY BUT WILL REMAIN QUITE COLD WITH CLOUDS ROLLING BACK IN IN THE AFTERNOON AS FAST MOVING CLIPPER DIVES SE TOWARD THE AREA. VERY LITTLE CHANGE IN MODEL GUIDANCE IN HANDLING THIS WAVE WITH SWATH OF ACCUMULATING VERY FLUFFIFIED/HIGH RATION SNOW LIKELY ACROSS NORTHERN/CENTRAL ILLINOIS FRIDAY NIGHT INTO SATURDAY MORNING. DESPITE LIMITED MOISTURE...HIGH SNOW:LIQUID RATIOS COULD SUPPORT SOLID 2-3 INCH BAND OF SNOW...WITH BEST PROJECTIONS AT THIS POINT PLACING THE HEAVIEST SNOW ALONG OR SOUTH OF I-80. GIVEN HOW LOW AMPLITUDE THIS WAVE IS WOULD NOT BE A STRETCH TO ENVISION LATER RUNS REFINING THE TRACK A BIT...BUT EVEN WITH THAT IN MIND FELT FAIRLY COMFORTABLE CONTINUING THE TREND OF BUMPING POPS UP A BIT HIGHER AGAIN THIS MORNING. SEEMINGLY NEVER ENDING PARADE OF CLIPPERS ARE PROGGED TO CONTINUE TO PIVOT AROUND THE BASE OF THE TROUGH HEADING INTO NEXT WEEK. THE 00Z ECMWF HAS COME IN A BIT DEEPER AND FARTHER WEST WITH THE POLAR VORTEX OVER THE REGION WHICH WOULD PLACE OUR CWA CLOSER TO THE COLD SIDE OF THE PATH OF THESE CLIPPERS AND ALSO CLOSER TO POTENTIAL LIGHT ACCUMULATING SNOWS. THE GEM...GFS...AND PREVIOUS ECMWF WERE QUICKER TO WEAKEN THE POLAR VORTEX ALLOWING THE CLIPPERS TO PASS TO OUR NORTH KEEPING US DRY WITH ALTERNATING BOUTS OF ABOVE AVERAGE TEMPS AND SLIGHT COOL DOWNS WITH A TREND TOWARD SLIGHTLY WEAKER COOL DOWNS WITH EACH WAVE. CONFIDENCE IS NOT TERRIBLY HIGH IN ANY ONE SOLUTION AT THIS POINT BUT A TOWARD MODERATING TEMPS DEFINITELY LOOKS REASONABLE HEADING INTO NEXT WEEK WITH LESS CERTAINTY REGARDING PRECIP CHANCES. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * W WIND GUSTING 20-25KT THROUGH EARLY AFTERNOON...THEN GUSTING 25-30KT LATE AFTN AND THROUGH THE EVENING. * SCATTERED -SN/FLURRIES PASSING OVER THE TERMINALS THROUGH 20Z THEN A PERIOD OF -SHSN LATE THIS AFTN/EARLY EVENING. * HIGH END MVFR TO LOW END VFR CIGS EXPECTED. JEE //DISCUSSION...UPDATED 12Z... ANOTHER MID LEVEL SHORT WAVE TROUGH WAS MOVING OVER NORTHERN WI... CENTRAL MN AND SE ND EARLY THIS MORNING CONTINUING TO GENERATE LIGHT SNOW ACROSS THE AREA. BANDS OF SOMEWHAT HEAVER SNOW OCCASIONALLY PASS OVER ORD AND/OR MDW AND BRIEFLY DROP VISIBILITY DOWN TO 3-5SM. THIS SNOW WILL PERSIST UNTIL THE TROUGH AXIS PASSES BY...WHICH IS EXPECTED IN THE 13Z TO 15Z WINDOW. SOME FLURRIES MAY LINGER THE REST OF THE MORNING BUT WILL NOT BE A RESTRICTION TO VISIBILITY. ANOTHER SHORT WAVE TROUGH...CURRENTLY OVER NORTHERN ND AND MN...WILL CONTINUE TO DROP ESE THIS MORNING AND MOVE TO OVER SE WI...NORTHERN IL AND SOUTHERN IA BY 00Z. SNOWFALL OF ANY SIGNIFICANCE FROM THIS DISTURBANCE IS EXPECTED TO REMAIN MAINLY TO THE NW AND N OF THE CHI AREA WITH JUST MORE FLURRIES...AND POSSIBLY SOME VERY LIGHT SNOW SHOWERS...FOR THE LOCAL AREA DURING THE LATE AFTERNOON AND EARLY EVENING. WINDS SETTLED DOWN DURING THE OVERNIGHT THE TIGHTER PRESSURE GRADIENT SHIFTED E. THE GRADIENT TIGHTENS AGAIN THIS MORNING WITH W-WNW WINDS GUSTING BACK UP INTO 25-30KT RANGE BY LATE MORNING AS THE HIGH PRESSURE RIDGE THAT EXTENDS S ACROSS SW SASKATCHEWAN SE TO THE CENTRAL PLAINS GRADUALLY MOVES SE. WITH THE HIGH CONTINUING TO THE SE THIS EVENING AND OVERNIGHT WINDS WILL DROP OFF AGAIN AS THE GRADIENT ONCE AGAIN RELAXES. MODEL RH FIELDS OF THE LOWER LAYERS SUGGEST THE CURRENT MVFR CEILINGS WILL RISE TO VFR THIS MORNING THEN DROP BACK TO MVFR THIS AFTERNOON. TRS //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH CONFIDENCE IN PRECIP FCST...MEDIUM CONFIDENCE IN VSBY ASSOCIATED WITH -SN. * HIGH CONFIDENCE IN ALL OTHER FCST ELEMENTS. JEE //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... 12Z... FRIDAY NIGHT...ACCUMULATING SNOW BECOMING LIKELY. MVFR BECOMING IFR. SATURDAY...MVFR WITH A CHANCE OF IFR SNOW SHOWERS...MAINLY IN THE MORNING. SUNDAY...MVFR. MONDAY...VFR. TUESDAY...VFR. WEDNESDAY...VFR. TRS && .MARINE... 446 AM CST DEEP LOW PRESSURE HAS MOVED FROM GEORGIAN BAY INTO SW QUEBEC DURING LATE WED EVENING AND EARLY THIS MORNING AND WILL CONTINUE TO MOVE FURTHER OFF TO THE NE. W TO WNW WINDS HAVE SLACKENED A BIT AS A RESULT OR THE DECREASING PRESSURE GRADIENT OVER LAKE MI THOUGH A FEW COASTAL OBSERVATION SITES ALONG THE IN AND FAR SW LOWER MI SHORED CONTINUED TO MEASURE SOME 35-40KT GALE FORCE GUSTS. WINDS WILL CONTINUE TO GRADUALLY DIMINISH DURING THE PREDAWN AND EARLY MORNING HOURS BUT WILL REMAIN BRISK AS STRONG HIGH PRESSURE CONTINUES TO BUILD SE FROM SOUTHERN SASKATCHEWAN ACROSS THE NORTHERN AND CENTRAL PLAINS TODAY. WINDS WILL INCREASE AND REACH GALES ON THE SOUTH PORTION OF THE LAKE BY MID AFTERNOON AS A SURFACE TROUGH DROPS SE DOWN THE LAKE SPREADING AND ANOTHER SURGE OF COLD AIR OVER THE REGION. GALE FORCE WINDS AND VERY COLD AIR WILL RESULT IN FREEZING SPRAY ACROSS THE LAKE. GALES WILL CONTINUE INTO LATE TONIGHT. BY FRIDAY MORNING A LARGE AREA OF HIGH PRESSURE WILL BE CENTERED OVER IA AND MO. THE PRESSURE GRADIENT DECREASES AS THE CENTER OF THE HIGH MOVES NEARER TO THE AREA AND WINDS ON THE LAKE WILL DIMINISH TO BELOW GALE FORCE BY FRI MORNING. NW WINDS GRADUALLY BACK TO SW DURING FRI AS THE CENTER OF THE HIGH MOVES TO KY AND TN BY LATE IN THE AFTERNOON. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WIND CHILL ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010- ILZ011...MIDNIGHT FRIDAY TO 10 AM FRIDAY. IN...NONE. LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 PM THURSDAY TO 6 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 10 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 PM FRIDAY. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1119 AM MST THU JAN 31 2013 .UPDATE... ISSUED AT 1115 AM MST THU JAN 31 2013 UPDATED TEMPERATURES FOR TODAY. COLD AIR IS MAKING ITS IMPACT ESPECIALLY IN THE EASTERN FA WITH MCK TEMPERATURES STEADILY FALLING ABOUT A DEGREE PER HOUR. EXPECT THAT TREND TO WORK ITS WAY SLOWLY WEST ACROSS THE FA. ALSO LOWERED TONIGHT AND FRIDAY TEMPERATURES. && .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 412 AM MST THU JAN 31 2013 FORECAST PROBLEMS WILL PROBLEMATIC TEMPERATURE FORECAST INTO TONIGHT AND HOW MUCH TO WARM UP THE HIGH TEMPERATURES INTO SATURDAY. SATELLITE SHOWING A BROAD UPPER TROUGH OVER THE TROUGH OVER THE WESTERN AND CENTRAL PACIFIC WITH A RIDGE ALONG THE WEST COAST OF NORTH AMERICA. A COUPLE OF SYSTEMS COMING INTO THE RIDGE ARE BEATING IT DOWN. A STRONG AND COLD SYSTEM IS DIGGING INTO THE NORTH CENTRAL PORTION OF THE COUNTRY. VERY COLD AIR MASS HAS MOVED FURTHER SOUTH FROM YESTERDAY AND IS NOT TOO FAR NORTH AND EAST OF OUR AREA. MODELS INITIALIZED WELL AT JET LEVEL WITH THE CANADIAN...GFS...AND NAM DOING THE BEST. MODELS INITIALIZED WELL AT MID LEVELS WITH THE GFS...CANADIAN...AND NAM DOING SLIGHTLY BETTER. LARGER SCALE MODELS DO NOT HAVE THE BACKDOOR COLD FRONT FAR ENOUGH SOUTH AND WEST BY 06Z...OH SURPRISE. THE RUC HAS CONTINUED TO GET BETTER AS THE NIGHT HAS PROGRESSED. OUTSIDE OF THE RUC ON THE LOW LEVEL THERMAL FIELD...THE ECMWF AND GFS WERE DOING A LITTLE BETTER THAN THE UKMET AND NAM. TODAY/TONIGHT...VERY THICK CLOUD COVER HAS SPREAD OVER THE AREA THROUGH THE NIGHT. WHAT THIS HAS DONE HAS PREVENTED ANY FALL OF THE TEMPERATURES AND IN FACT HAS CAUSED THE TEMPERATURES TO RISE SOME. NWP OUTPUT MUST BE UNDERDOING THIS CLOUD COVER AND IS TOO COOL WITH TEMPERATURES. THIS CLOUD COVER IS BEING CAUSED BY STRONG MID TO UPPER LEVEL JET. SOUNDINGS AND PLAN VIEW RELATIVE HUMIDITY PLOTS SHOW THIS CLOUD COVER LASTING MOST OF THE DAY...ESPECIALLY IN THE NORTHEAST PORTION. BACKDOOR COLD FRONT WITH VERY COLD AIR BEHIND IT HAS BEEN MOVING STEADILY TOWARD THE AREA THROUGH THE NIGHT AND IS NOT THAT FAR AWAY. RUC IS CATCHING ONTO THIS AT THIS TIME. INITIALLY WAS GOING TO CUT HIGH TEMPERATURES FROM GOING FORECAST BUT CLOUD COVER HAS COMPLICATED THAT. SO WILL BE STARTING MUCH WARMER THAN WHAT MOST OF THE MODELS SAY. FRONT SAGS ACROSS THE AREA THROUGH THE DAY WITH SOME LOCATIONS IN THE NORTHEAST HALF TO TWO THIRDS REACHING THEIR MAX BY 18Z. SO COMBINING REALITY AND THE RUC ADJUSTED MAX TEMPERATURES UP BUT HAVE EXTREMELY LOW CONFIDENCE ABOUT THIS. DID NOT GOES AS WARM AS IT BECAUSE OF THE CLOUD COVER. HRRR WOULD INDICATE HIGH TEMPERATURES ABOUT 10 DEGREES WARMER IN THE SOUTHWEST PORTION OF THE AREA THAT WHAT I HAVE. LEFT FRONT QUADRANT OF INCOMING JET WILL CONTINUE TO AFFECT THE NORTHEAST HALF TO TWO THIRDS OF THE AREA INTO EARLY AFTERNOON. SEVERAL STATIONS HAVE REPORTED BRIEF PERIODS OF FLURRIES. ALL MODEL OUTPUT AGREES IN PLACING LIGHT QPF IN THE ABOVE MENTIONED AREA. SREF PROBABILITIES AGREE WITH THAT. IT MAKES SENSE WITH THE JET... MESOSCALE FORCING AND LAPSE RATES IN PLACE. HOWEVER...DRIER AIR IN THE LOWEST LAYERS. SO INTRODUCED SCATTERED FLURRIES THROUGH MIDDAY WHEN THE FORCING AND MOISTURE LEAVE. PROBLEMATIC MIN FORECAST AS WELL. WINDS SHIFT AROUND TO A SOUTH DIRECTION PRETTY QUICKLY. NAM IS THE MOST AGGRESSIVE BUT IS SUPPORTED BY OTHER MODEL OUTPUT IN BRINGING STRATUS AND FOG DURING THE LATE EVENING AND OVERNIGHT HOURS. THIS IS AS THE COLD FRONT RETREATS BACK AS A WARM FRONT AND ALL THE MODELS ARE VERY SIMILAR IN DOING IT. MINS WILL PROBABLY BE REACHED IN THE EVENING ESPECIALLY IN THE WEST AND POSSIBLY IN THE SOUTH AND A NON-DIURNAL CURVE WILL HAVE TO BE INTRODUCED. BELIEVE MODELS ARE TOO COOL AND WENT ABOVE THE GUIDANCE. 06Z NAM WAS MUCH MORE ROBUST IN BRINGING IN THE STRATUS AND FOG. NAM HAS BEEN SHOWING THIS FOR A FEW DAYS PLUS THOSE SOUTH WINDS WILL BE BLOWING ACROSS A SNOW FIELD. SO EXPANDED THE PATCHY FOG THAT WAS IN THERE. FRIDAY/FRIDAY NIGHT...STRATUS AND FOG GET PUSHED EAST PRETTY FAST BY THE STRENGTHENING DOWNSLOPE WINDS. THERE MAY BE SOME HIGHER LEVEL CLOUD COVER AROUND. INCOMING SHORTWAVE TROUGH IN NORTHWEST FLOW ALOFT WILL PUSH A WEAK FRONT OR SURFACE TROUGH THROUGH LATER IN THE DAY BUT IT LOOKS LIKE WINDS WILL BE FROM A DOWNSLOPE DIRECTION. SO ENDED UP RAISING THE MAXES A LITTLE. LEFT FRONT QUADRANT OF JET WILL AFFECT THE NORTHERN PORTION OF THE AREA DURING THE NIGHT AS WELL AS THE ABOVE MENTIONED SHORTWAVE TROUGH...WHICH HAPPENS TO BE THE ONE TOPPING THE RIDGE RIGHT NOW NEAR WESTERN CANADA. ALL MODELS AGREE THAT THIS SYSTEM WILL HAVE A VERY STRONG PV ANOMALY AS WELL. MODELS DO NOT SHOW A LOT OF MOISTURE IN THE COLUMN BUT STRENGTH OF SYSTEM SHOULD COMPENSATE FOR THAT. SO EXPANDED THE SPRINKLES AND FLURRIES OVER A LARGER AREA AND THROUGH THE EVENING HOURS. SATURDAY/SATURDAY NIGHT...RIDGING AND DRYING ALOFT PUSH INTO THE AREA FOR SATURDAY. SO WILL HAVE PLENTY OF SUN ALONG WITH STRONG DOWNSLOPE WINDS. SO RAISED MAXES MORE AND I MAY NOT BE WARM ENOUGH AS I BELIEVE MODELS ARE TOO COOL. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 246 AM MST THU JAN 31 2013 MODEL AGREEMENT IS FAIRLY GOOD IN THE EXTENDED FORECAST. ALL SOLUTIONS ARE POINTING TO A TAME WEATHER PATTERN WITHOUT ANY BIG WEATHER CHANGES OR PRECIPITATION CHANCES. A SYSTEM WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES ON MONDAY...BRINGING ONLY A WIND SHIFT AND TEMPERATURES A DEGREE OR TWO COOLER. AFTER THAT...A RIDGE OF HIGH PRESSURE BUILDS BACK IN FROM THE WEST. TEMPERATURES SHOULD BE WELL ABOVE NORMAL FOR THIS TIME OF YEAR THROUGHOUT THE EXTENDED FORECAST. HIGHS SHOULD BE IN THE 50S FOR SUNDAY THROUGH TUESDAY...WITH HIGHS CLIMBING INTO THE 60S BY THE MIDDLE OF NEXT WEEK. GUIDANCE HAS PULLED BACK SOMEWHAT FOR HIGH TEMPERATURES ON SUNDAY BUT STILL THINK TEMPERATURES NEARING 60 FOR EASTERN COLORADO IS NOT OUT OF THE QUESTION. THE ONLY OTHER CONCERN FOR THE EXTENDED FORECAST WAS LOW TEMPERATURES. THE INITIALIZATION PROCEDURE INPUT LOW TEMPERATURES THAT WERE LIKELY TOO WARM. CONSIDERING THE ONGOING DROUGHT CONDITIONS AND MEX AND ECE GUIDANCE SUGGESTING TEMPERATURES MUCH LOWER THAN THE INITIALIZATION...HAVE LOWERED LOW TEMPERATURES A DEGREE OR TWO. GUIDANCE IS ALTERED BY CLIMATOLOGICAL DATA SO THIS COULD BE THE REASON MEX AND ECE GUIDANCE IS BEING HELD DOWN SOMEWHAT. HOWEVER...THE HIGHER LOW TEMPS SEEMED A LITTLE UNREASONABLE WITH CLEAR SKIES AND LIGHT WINDS THROUGHOUT THE EXTENDED PERIOD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1040 AM MST THU JAN 31 2013 VFR TO MVFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT BOTH GLD AND MCK. FOR THE REST OF THE DAY...SOME BREEZY WINDS AND CLEARING SKIES AT GLD...WHILE CURRENT CLOUDS WILL STICK AROUND AT MCK. THIS EVENING A BACKDOOR COLD FRONT WILL PUSH FROM NORTHEAST TO SOUTHWEST...ARRIVING AT MCK AROUND 22Z. THIS WILL SHIFT WINDS...THOUGH WIND SPEEDS AT BOTH TERMINALS WILL BE LIGHT /LESS THAN 10KTS/ THROUGHOUT THE OVERNIGHT PERIOD. SOME PATCHY FOG AND LOW STRATUS CLOUDS ARE EXPECTED...WITH CONDITIONS MAINLY REMAINING MVFR. BEST CHANCE FOR FOG WILL BE AT GLD...THOUGH IF FOG REACHES MCK IT MAY STICK AROUND INTO THE MID-MORNING HOURS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...032 SHORT TERM...BULLER LONG TERM...RRH AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1040 AM MST THU JAN 31 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 412 AM MST THU JAN 31 2013 FORECAST PROBLEMS WILL PROBLEMATIC TEMPERATURE FORECAST INTO TONIGHT AND HOW MUCH TO WARM UP THE HIGH TEMPERATURES INTO SATURDAY. SATELLITE SHOWING A BROAD UPPER TROUGH OVER THE TROUGH OVER THE WESTERN AND CENTRAL PACIFIC WITH A RIDGE ALONG THE WEST COAST OF NORTH AMERICA. A COUPLE OF SYSTEMS COMING INTO THE RIDGE ARE BEATING IT DOWN. A STRONG AND COLD SYSTEM IS DIGGING INTO THE NORTH CENTRAL PORTION OF THE COUNTRY. VERY COLD AIR MASS HAS MOVED FURTHER SOUTH FROM YESTERDAY AND IS NOT TOO FAR NORTH AND EAST OF OUR AREA. MODELS INITIALIZED WELL AT JET LEVEL WITH THE CANADIAN...GFS...AND NAM DOING THE BEST. MODELS INITIALIZED WELL AT MID LEVELS WITH THE GFS...CANADIAN...AND NAM DOING SLIGHTLY BETTER. LARGER SCALE MODELS DO NOT HAVE THE BACKDOOR COLD FRONT FAR ENOUGH SOUTH AND WEST BY 06Z...OH SURPRISE. THE RUC HAS CONTINUED TO GET BETTER AS THE NIGHT HAS PROGRESSED. OUTSIDE OF THE RUC ON THE LOW LEVEL THERMAL FIELD...THE ECMWF AND GFS WERE DOING A LITTLE BETTER THAN THE UKMET AND NAM. TODAY/TONIGHT...VERY THICK CLOUD COVER HAS SPREAD OVER THE AREA THROUGH THE NIGHT. WHAT THIS HAS DONE HAS PREVENTED ANY FALL OF THE TEMPERATURES AND IN FACT HAS CAUSED THE TEMPERATURES TO RISE SOME. NWP OUTPUT MUST BE UNDERDOING THIS CLOUD COVER AND IS TOO COOL WITH TEMPERATURES. THIS CLOUD COVER IS BEING CAUSED BY STRONG MID TO UPPER LEVEL JET. SOUNDINGS AND PLAN VIEW RELATIVE HUMIDITY PLOTS SHOW THIS CLOUD COVER LASTING MOST OF THE DAY...ESPECIALLY IN THE NORTHEAST PORTION. BACKDOOR COLD FRONT WITH VERY COLD AIR BEHIND IT HAS BEEN MOVING STEADILY TOWARD THE AREA THROUGH THE NIGHT AND IS NOT THAT FAR AWAY. RUC IS CATCHING ONTO THIS AT THIS TIME. INITIALLY WAS GOING TO CUT HIGH TEMPERATURES FROM GOING FORECAST BUT CLOUD COVER HAS COMPLICATED THAT. SO WILL BE STARTING MUCH WARMER THAN WHAT MOST OF THE MODELS SAY. FRONT SAGS ACROSS THE AREA THROUGH THE DAY WITH SOME LOCATIONS IN THE NORTHEAST HALF TO TWO THIRDS REACHING THEIR MAX BY 18Z. SO COMBINING REALITY AND THE RUC ADJUSTED MAX TEMPERATURES UP BUT HAVE EXTREMELY LOW CONFIDENCE ABOUT THIS. DID NOT GOES AS WARM AS IT BECAUSE OF THE CLOUD COVER. HRRR WOULD INDICATE HIGH TEMPERATURES ABOUT 10 DEGREES WARMER IN THE SOUTHWEST PORTION OF THE AREA THAT WHAT I HAVE. LEFT FRONT QUADRANT OF INCOMING JET WILL CONTINUE TO AFFECT THE NORTHEAST HALF TO TWO THIRDS OF THE AREA INTO EARLY AFTERNOON. SEVERAL STATIONS HAVE REPORTED BRIEF PERIODS OF FLURRIES. ALL MODEL OUTPUT AGREES IN PLACING LIGHT QPF IN THE ABOVE MENTIONED AREA. SREF PROBABILITIES AGREE WITH THAT. IT MAKES SENSE WITH THE JET... MESOSCALE FORCING AND LAPSE RATES IN PLACE. HOWEVER...DRIER AIR IN THE LOWEST LAYERS. SO INTRODUCED SCATTERED FLURRIES THROUGH MIDDAY WHEN THE FORCING AND MOISTURE LEAVE. PROBLEMATIC MIN FORECAST AS WELL. WINDS SHIFT AROUND TO A SOUTH DIRECTION PRETTY QUICKLY. NAM IS THE MOST AGGRESSIVE BUT IS SUPPORTED BY OTHER MODEL OUTPUT IN BRINGING STRATUS AND FOG DURING THE LATE EVENING AND OVERNIGHT HOURS. THIS IS AS THE COLD FRONT RETREATS BACK AS A WARM FRONT AND ALL THE MODELS ARE VERY SIMILAR IN DOING IT. MINS WILL PROBABLY BE REACHED IN THE EVENING ESPECIALLY IN THE WEST AND POSSIBLY IN THE SOUTH AND A NON-DIURNAL CURVE WILL HAVE TO BE INTRODUCED. BELIEVE MODELS ARE TOO COOL AND WENT ABOVE THE GUIDANCE. 06Z NAM WAS MUCH MORE ROBUST IN BRINGING IN THE STRATUS AND FOG. NAM HAS BEEN SHOWING THIS FOR A FEW DAYS PLUS THOSE SOUTH WINDS WILL BE BLOWING ACROSS A SNOW FIELD. SO EXPANDED THE PATCHY FOG THAT WAS IN THERE. FRIDAY/FRIDAY NIGHT...STRATUS AND FOG GET PUSHED EAST PRETTY FAST BY THE STRENGTHENING DOWNSLOPE WINDS. THERE MAY BE SOME HIGHER LEVEL CLOUD COVER AROUND. INCOMING SHORTWAVE TROUGH IN NORTHWEST FLOW ALOFT WILL PUSH A WEAK FRONT OR SURFACE TROUGH THROUGH LATER IN THE DAY BUT IT LOOKS LIKE WINDS WILL BE FROM A DOWNSLOPE DIRECTION. SO ENDED UP RAISING THE MAXES A LITTLE. LEFT FRONT QUADRANT OF JET WILL AFFECT THE NORTHERN PORTION OF THE AREA DURING THE NIGHT AS WELL AS THE ABOVE MENTIONED SHORTWAVE TROUGH...WHICH HAPPENS TO BE THE ONE TOPPING THE RIDGE RIGHT NOW NEAR WESTERN CANADA. ALL MODELS AGREE THAT THIS SYSTEM WILL HAVE A VERY STRONG PV ANOMALY AS WELL. MODELS DO NOT SHOW A LOT OF MOISTURE IN THE COLUMN BUT STRENGTH OF SYSTEM SHOULD COMPENSATE FOR THAT. SO EXPANDED THE SPRINKLES AND FLURRIES OVER A LARGER AREA AND THROUGH THE EVENING HOURS. SATURDAY/SATURDAY NIGHT...RIDGING AND DRYING ALOFT PUSH INTO THE AREA FOR SATURDAY. SO WILL HAVE PLENTY OF SUN ALONG WITH STRONG DOWNSLOPE WINDS. SO RAISED MAXES MORE AND I MAY NOT BE WARM ENOUGH AS I BELIEVE MODELS ARE TOO COOL. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 246 AM MST THU JAN 31 2013 MODEL AGREEMENT IS FAIRLY GOOD IN THE EXTENDED FORECAST. ALL SOLUTIONS ARE POINTING TO A TAME WEATHER PATTERN WITHOUT ANY BIG WEATHER CHANGES OR PRECIPITATION CHANCES. A SYSTEM WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES ON MONDAY...BRINGING ONLY A WIND SHIFT AND TEMPERATURES A DEGREE OR TWO COOLER. AFTER THAT...A RIDGE OF HIGH PRESSURE BUILDS BACK IN FROM THE WEST. TEMPERATURES SHOULD BE WELL ABOVE NORMAL FOR THIS TIME OF YEAR THROUGHOUT THE EXTENDED FORECAST. HIGHS SHOULD BE IN THE 50S FOR SUNDAY THROUGH TUESDAY...WITH HIGHS CLIMBING INTO THE 60S BY THE MIDDLE OF NEXT WEEK. GUIDANCE HAS PULLED BACK SOMEWHAT FOR HIGH TEMPERATURES ON SUNDAY BUT STILL THINK TEMPERATURES NEARING 60 FOR EASTERN COLORADO IS NOT OUT OF THE QUESTION. THE ONLY OTHER CONCERN FOR THE EXTENDED FORECAST WAS LOW TEMPERATURES. THE INITIALIZATION PROCEDURE INPUT LOW TEMPERATURES THAT WERE LIKELY TOO WARM. CONSIDERING THE ONGOING DROUGHT CONDITIONS AND MEX AND ECE GUIDANCE SUGGESTING TEMPERATURES MUCH LOWER THAN THE INITIALIZATION...HAVE LOWERED LOW TEMPERATURES A DEGREE OR TWO. GUIDANCE IS ALTERED BY CLIMATOLOGICAL DATA SO THIS COULD BE THE REASON MEX AND ECE GUIDANCE IS BEING HELD DOWN SOMEWHAT. HOWEVER...THE HIGHER LOW TEMPS SEEMED A LITTLE UNREASONABLE WITH CLEAR SKIES AND LIGHT WINDS THROUGHOUT THE EXTENDED PERIOD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1040 AM MST THU JAN 31 2013 VFR TO MVFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT BOTH GLD AND MCK. FOR THE REST OF THE DAY...SOME BREEZY WINDS AND CLEARING SKIES AT GLD...WHILE CURRENT CLOUDS WILL STICK AROUND AT MCK. THIS EVENING A BACKDOOR COLD FRONT WILL PUSH FROM NORTHEAST TO SOUTHWEST...ARRIVING AT MCK AROUND 22Z. THIS WILL SHIFT WINDS...THOUGH WIND SPEEDS AT BOTH TERMINALS WILL BE LIGHT /LESS THAN 10KTS/ THROUGHOUT THE OVERNIGHT PERIOD. SOME PATCHY FOG AND LOW STRATUS CLOUDS ARE EXPECTED...WITH CONDITIONS MAINLY REMAINING MVFR. BEST CHANCE FOR FOG WILL BE AT GLD...THOUGH IF FOG REACHES MCK IT MAY STICK AROUND INTO THE MID-MORNING HOURS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...RRH AVIATION...JJM
AREA FORECAST DISCUSSION
NWS PADUCAH KY
339 PM CST THU JAN 31 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 315 PM CST THU JAN 31 2013 A STRONG ARCTIC FRONT IS COMBINING WITH AN UPPER LEVEL IMPULSE SHOOTING QUICKLY EASTWARD TOWARDS THE REGION TO PRODUCE BANDS OF LOCALLY HEAVY SNOWS ACROSS MISSOURI THIS AFTERNOON. MESO MODELS...ESP THE RUC...AS WELL THE 12Z GFS TO A LESSER EXTENT ARE CATCHING ONTO THIS. THE RUC BRINGS THE BANDING PRECIP...WHICH MAY BEGIN BRIEFLY AS LIGHT RAIN...INTO SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS DURING THE MID TO LATE AFTERNOON HOURS IN THE POST FRONTAL ENVIRONMENT. THIS SNOW COULD QUICKLY BECOME HEAVY AT TIMES IN E TO W ORIENTED BANDS ACROSS THE REGION. THIS AREA OF PRECIPITATION WILL RAPIDLY MOVE EAST INTO ACROSS THE REMAINDER OF THE REGION EARLY TONIGHT. THE SNOW WILL LIKELY TAPER OFF JUST AS QUICKLY AS IT BEGAN OVER SOUTHEAST MISSOURI EARLY TONIGHT...THEN END OVER THE REST OF THE REGION BY AROUND MIDNIGHT AS THE IMPULSE TRAVELS OFF TO THE EAST ON THE NORTH SIDE OF THE COLD FRONT. THE MAIN IMPACT WILL COME WITH BURSTS OF LOCALLY HEAVY SNOW IN EAST TO WEST BANDING PRECIPITATION. WHERE...AND HOW NARROW OR THICK THESE BANDS OF SNOW BECOME WILL DETERMINE HOW MUCH SNOW A GIVEN LOCATION RECEIVES. AT THIS TIME...IT SEEMS LIKE MUCH OF THE ADVISORY AREA WILL SEE UP TO A QUICK INCH OR SO OF SNOW. HOWEVER...THERE WILL LIKELY BE LOCALLY HEAVIER BANDS THAT PRODUCE A QUICK 2 TO 3 INCHES OF SNOW. MOTORISTS SHOULD BE PREPARED FOR RAPIDLY FLUCTUATING VISIBILITIES TO UNDER A QUARTER MILE AT TIMES. OTHER IMPACTS INCLUDE THE FACT THAT MUCH OF THE SNOW WILL OCCUR DURING INCREASED TRAFFIC BETWEEN 4 PM AND 7 PM...ESPECIALLY IN SOUTHEAST MISSOURI...SOUTHERN ILLINOIS AND THE WESTERN TIP OF KENTUCKY AND SOUTHWEST INDIANA. TRUE ARCTIC BLAST...THOUGH FAIRLY BRIEF...WILL FOLLOW QUICKLY IN THE WAKE OF THIS SYSTEM. SHOULD SEE TEMPS STAY BELOW FREEZING ALL DAY FRIDAY...WELL BELOW FREEZING IF WE GET A FRESH LAYER OF SNOWFALL. SAME WITH FRI NIGHT. IF ANY SNOW IS ON THE GROUND...TEMPS WILL LIKELY CHALLENGE SINGLE DIGITS IN THOSE LOCATIONS. WEAK DISTURBANCE AND WARM FRONT WILL LIKE PASS NEAR THE REGION SAT. RIGHT NOW LOOKS LIKE A NON EVENT...UNLESS THE VERY LIGHT PRECIP BEGINS EARLY ENOUGH SAT AM. IF SO...THEN A LITTLE LIGHT SNOW...SLEET OF FREEZING RAIN WOULD BE POSSIBLE BEFORE SFC TEMPS WARM ABOVE FREEZING. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 315 PM CST THU JAN 31 2013 A FAIRLY ACTIVE PATTERN SETTING UP FOR NEXT WEEK...WITH SEVERAL WEATHER SYSTEMS TO KEEP AN EYE ON. HOWEVER...THEY ARE WEAK SYSTEMS...EXCEPT FOR THE ONE SLATED FOR WED NIGHT/THURSDAY...WHICH HAS THE BEST POTENTIAL RIGHT NOW OF BRINGING MORE WIDESPREAD PRECIPITATION. ON SUNDAY...WE SHOULD SEE SFC HIGH PRESSURE SLOWLY OOZE INTO THE REGION...WITH NORTHWEST FLOW ALOFT. MODELS DIVERGE AFTER THIS...AS THE 00Z ECMWF SHOVES THE SFC HIGH EAST SUNDAY NIGHT AS ANOTHER FRONTAL SYSTEM BARRELS DOWN FROM THE NORTHWEST. A WEAK WAVE ALOFT ACCOMPANIES THIS FEATURE BUT MOST OF THE ENERGY STAYS TO OUR SOUTHWEST. THE 06Z ECMWF SHOWED A GLANCING SHOT FOR PRECIP ACROSS SE MO/SW KY ON MONDAY...BUT THE 12Z RUN IS MUCH MORE AGGRESSIVE AND PAINTS QPF OVER THE ENTIRE AREA. THE GFS IS MUCH SLOWER WITH THE PROGRESSION OF THIS SYSTEM WITH ITS 06Z RUN...AND SHOWS THE SFC HIGH RETREATING MONDAY MORNING WITH THE FRONTAL SYSTEM APPROACHING LATER IN THE DAY...BUT WEAKENING SO MUCH THAT IT REALLY HAS LITTLE IMPACT ON OUR AREA. THE 12Z GFS RUN IS MORE IN LINE WITH THE TIMING OF THE 00Z ECMWF NOW...BUT STILL SPLITS OUR AREA WHEN IT COMES TO RAIN CHANCES...WITH THE MAIN PRECIP SKIRTING BY TO OUR NORTH AND SOUTH. WILL START OUT WITH A SLIGHT CHANCE ACROSS SOUTHERN MO AND SW KY. ANOTHER LOW PRESSURE SYSTEM COMES DOWN OUT OF THE NORTHERN PLAINS AND INTO THE MIDWEST LATE MONDAY NIGHT AND INTO TUESDAY. AGAIN...MODELS DO NOT AGREE ON THIS SYSTEM EITHER...WITH THE ECMWF MUCH DEEPER WITH THE UPPER TROUGH AND HENCE...IT INDICATES THAT SOME PRECIP CHANCES MAY FLIRT WITH THE WABASH VALLEY OF SE IL AND THE EVV TRI STATE REGION ON TUESDAY. SO EITHER WAY...IT DOES NOT LOOK LIKE TOO BIG A DEAL SINCE MOST OF THE MOISTURE STAYS FURTHER NORTH AND EAST OF THE AREA. MODEL SOUNDINGS INDICATE THAT THE LOWEST FEW THOUSAND FT WILL BE WARM ENOUGH THAT EVEN IF IT DID PRECIPITATE...IT SHOULD BE LIQUID. BUT THERE IS QUITE A DIFFERENCE IN LOW LEVEL TEMPS BTWN THE GFS AND ECWMF DUE TO THE DEGREE OF THE AMPLITUDE OF THE TROUGH COMING THROUGH. TUESDAY NIGHT AND WEDNESDAY...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...BUT WILL QUICKLY MOVE EAST WED NIGHT. OUR NEXT SYSTEM COULD IMPACT US AS EARLY AS LATE WED...OR HOLD OFF UNTIL THURSDAY. HOWEVER...THE SIGNAL IS FAIRLY STRONG THAT WE WILL SEE SOME PRECIPITATION ON THURSDAY...WITH SUPPORT OF THE GFS ENSEMBLES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1122 AM CST THU JAN 31 2013 BKN VFR DECK AT KEVV/KOWB ALONG WITH SOME MID CLOUDS AROUND. SCT TO MID CLOUDS POSSIBLE ELSEWHERE AS WELL. ARCTIC COLD FRONT OFF TO THE NORTHWEST WILL MOVE INTO THE AREA LATER THIS AFTERNOON. GUSTY WSW WINDS AHEAD OF IT. HAVE A -SN CHANCE FROM 21Z- 01Z WITH THE FRONTAL PASSAGE. CLEARING AFTER THAT...WITH GUSTY NW WINDS POST FRONTAL...WHICH WILL SLACKEN BY 12Z. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ILZ081>094. MO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR MOZ076- 086-087-100-107>112-114. IN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR INZ081- 082-085>088. KY...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR KYZ001>022. && $$ SHORT TERM...MEFFERT LONG TERM....CW AVIATION...CW
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
240 PM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 12 NOON UPDATE... WE`VE PUSHED BACK THE START TIME OF THE LES WRNG BY A FEW HRS IN NRN ONEIDA (NOW 21Z). BASED ON THE LATEST KBUF VWP (STILL A 260 FLOW OVER A DEEP LYR)...AND OVERALL RADAR PRESENTATION...WE THINK THE ONSET OF THE +SN IN NRN ONEIDA WILL BE SOMEWHAT DELAYED FROM OUR EARLIER FCST. THE AMTS STILL LOOK REPRESENTATIVE...AS PARAMETERS SEEM FAVORABLE FOR FAIRLY INTENSE RATES...ONCE THE SNOW DOES FINALLY MOVE IN. 10 AM UPDATE... OUR CURRENT FCST IS IN EXCELLENT SHAPE ATTM...SO ONLY COSMETIC CHGS WERE MADE. AS STG CAA CONTS TO FILTER ACRS THE FA LATE THIS MRNG...LES BANDS ARE TRYING TO ORGANIZE OFF BOTH LKS ERIE AND ONT. AS JUDGED FROM THE 12Z RAOBS AT BUF/DTX...THE MIXED LYR EXTENDS UP TO ABT 750 MB...WITH A FAIR MOISTURE SUPPLY UNDERNEATH THE BASE OF THE INVERSION. GIVEN CONTD CYCLONIC FLOW...FURTHER COOLING WITH TIME...AND IF ANYTHING...A DEEPENING OF THE SYNOPTIC MOISTURE THIS AFTN AND EVE...THERE`S NO REASON NOT TO EXPECT THE DVLPMT OF FAIRLY STG LAKE-EFFECT PLUMES OFF BOTH LKS. IN-HOUSE CAPE/SHEAR NOMOGRAM SHOWS ENUF OVER-LAND INSTAB THROUGH THIS EVE (00-03Z)...SO THAT THE BANDS MAY TAKE ON SOMEWHAT OF A CELLULAR APPEARANCE...AT TIMES. HOWEVER...ORGANIZATION IS NOT LIKELY TO BE SERIOUSLY COMPROMISED. ALSO...THE CSTAR-DERIVED INLAND EXTENT APPLICATION DEPICTS A FAIRLY DEEP INLAND PENETRATION THROUGHOUT THE EVE HRS...AT LEAST...WITH A GOOD UPSTREAM CONNECTION TO HURON/NRN LK MI/SUPERIOR...AND ALSO STG 0-1 KM SPEED SHEAR. THIS ALSO SEEMS WELL SUPPORTED BY SIM REFLECTIVITY PRESENTATIONS FROM THE NAM12...LOCAL ARW...AND HRRR MODELS. BOTTOM LN...THINGS APPEAR WELL ON TRACK FOR THE LES WRNG IN NRN ONEIDA...WITH A PD OF VERY HVY SNOW ANTICIPATED...FROM ROUGHLY 22-06Z. GIVEN DEEP MOISTURE...AND EXCELLENT CRYSTAL GROWTH PARAMETERS...2-3"/HR RATES ARE NOT OUT OF THE QUESTION. ELSEWHERE (ONONDAGA/MADISON/SRN ONEIDA)...DESPITE SOME ANTICIPATED WEAKENING LTR TNT...AS THE BAND DROPS SWD...THERE MAY BE ENUF RESIDUAL INTENSITY FOR ADVSY-LVL ACCUMS. WE`LL RE-VISIT THIS SITN EARLY THIS AFTN. ACRS THE TWIN TIERS...SOME CONVECTIVE SHSN ARE LIKELY TO FORM BY MID TO LATE AFTN...AIDED A BIT BY ADVECTION OF MOISTURE FROM LKS ERIE AND SRN MI IN STG WRLY FLOW. OVERALL...THOUGH...THE NATURE OF THEM WILL REMAIN SCTD. AS FOR THE WINDS...THEY`RE LIKELY TO BE AT THEIR PEAK THROUGH ABT 18Z...WITH A SLOW DIMINISHING TREND THEREAFTER...AS JUDGED FROM ISALLOBARIC AND MOMENTUM TRANSFER PROGS. A STEADY OR SLOWLY FALLING TEMP TREND IS WELL HANDLED IN THE GRIDS...SO ONLY VERY MINOR TWEAKS WERE NEEDED. PREV DISC... 620 AM...WILL DROP THE FLOOD WATCH FOR ERN ZONES AS STEADY RAIN IS MOVG OUT. OTRW JUST MINOR NEAR TERM TWEEKS WITH NO SIG CHGS TO FCST. PREV BLO... 450 AM...DROPPED FLOOD WATCH FOR THE CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACK EDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACK EDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAINLY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF THE BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAY SHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... 230 PM UPDATE... LK EFFECT SNOW WL START OFF THE LONG TERM AS SYSTEM EXITS OFF OF THE EAST COAST. NW FLOW WL BRING CLD AIR ACRS THE LKS ALONG WITH NEAR SEASONAL TEMPS. CLIPPER TYPE LOW WL MV THRU THE UPR MIDWEST AND MID-ATLANTIC SPREADING LIGHT SNOW INTO THE REGION ON TUESDAY. 12Z MED RANGE GUIDANCE SHOWS SLIGHT DISCREPANCIES IN HOW FAR NORTH CLIPPER TRACKS ON MON NGT INTO TUESDAY. WITH GFS BEING FURTHER NORTH AND EC SUPPRESSED FURTHER TO THE SOUTH, HV SIDED WITH HPC GUIDANCE WITH LOW-MID RANGE CHC POPS FOR THIS TIME PD. SYSTEM WL SKIRT TO THE SOUTH AS HIPRES WL BUILD IN FM THE NORTH. HV ASSIGNED LOCHC POPS TO THE ENTIRE AREA FOR TUE NGT THEN THINKING IT WL TRANSITION TO A LGT LES EVENT ACRS FINGER LKS REGION WITH JUST FLURRIES ELSEWHERE. SFC HIPRES WL BUILD IN WED NGT AND THURSDAY. L/WV TROF FCST TO DROP INTO THE PLAINS TWD THE END OF THE PD WITH LIGHT SNOW SPREADING INTO CWA BY 12Z FRIDAY. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... 18Z UPDATE... SNOW HAS MOVED INTO ALL TERMINALS BEHIND COLD FRONT. WITH SCATTERED SNOW SHOWERS, CONDS WILL RANGE FROM VFR TO MVFR THOUGH AN OCCASIONAL IFR CANNOT BE RULED OUT. AS LAKE EFFECT BAND GETS ORGANIZED IFR VSBYS WILL MOVE INTO KRME AFTER 03Z AND KSYR AFTER 09Z. AT KELM AND KITH EXPECT MVFR CONDS TONIGHT WITH FLOW OFF OF LAKE ERIE THOUGH KBGM AND KAVP SHOULD REMAIN LOW VFR. WINDS OUT OF THE SOUTHWEST THIS AFTERNOON AROUND 25KTS WILL GUST TO 30-40KTS. WINDS WILL REMAIN GUSTY NEXT 24 HOURS THOUGH GUSTS WILL LESSEN TO AROUND 25KTS AND GRADUALLY SWITCH AROUND TO A MORE WEST-NORTHWEST DIRECTION. .OUTLOOK... SAT/SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. TUE...MVFR/IFR IN LIGHT SNOW AT ALL TERMINALS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST FRIDAY FOR NYZ009. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR NYZ022. LAKE EFFECT SNOW ADVISORY FROM 4 AM TO 7 PM EST FRIDAY FOR NYZ018-036-037. && $$ SYNOPSIS... NEAR TERM...MLJ SHORT TERM... LONG TERM...PVN AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
123 PM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 12 NOON UPDATE... WE`VE PUSHED BACK THE START TIME OF THE LES WRNG BY A FEW HRS IN NRN ONEIDA (NOW 21Z). BASED ON THE LATEST KBUF VWP (STILL A 260 FLOW OVER A DEEP LYR)...AND OVERALL RADAR PRESENTATION...WE THINK THE ONSET OF THE +SN IN NRN ONEIDA WILL BE SOMEWHAT DELAYED FROM OUR EARLIER FCST. THE AMTS STILL LOOK REPRESENTATIVE...AS PARAMETERS SEEM FAVORABLE FOR FAIRLY INTENSE RATES...ONCE THE SNOW DOES FINALLY MOVE IN. 10 AM UPDATE... OUR CURRENT FCST IS IN EXCELLENT SHAPE ATTM...SO ONLY COSMETIC CHGS WERE MADE. AS STG CAA CONTS TO FILTER ACRS THE FA LATE THIS MRNG...LES BANDS ARE TRYING TO ORGANIZE OFF BOTH LKS ERIE AND ONT. AS JUDGED FROM THE 12Z RAOBS AT BUF/DTX...THE MIXED LYR EXTENDS UP TO ABT 750 MB...WITH A FAIR MOISTURE SUPPLY UNDERNEATH THE BASE OF THE INVERSION. GIVEN CONTD CYCLONIC FLOW...FURTHER COOLING WITH TIME...AND IF ANYTHING...A DEEPENING OF THE SYNOPTIC MOISTURE THIS AFTN AND EVE...THERE`S NO REASON NOT TO EXPECT THE DVLPMT OF FAIRLY STG LAKE-EFFECT PLUMES OFF BOTH LKS. IN-HOUSE CAPE/SHEAR NOMOGRAM SHOWS ENUF OVER-LAND INSTAB THROUGH THIS EVE (00-03Z)...SO THAT THE BANDS MAY TAKE ON SOMEWHAT OF A CELLULAR APPEARANCE...AT TIMES. HOWEVER...ORGANIZATION IS NOT LIKELY TO BE SERIOUSLY COMPROMISED. ALSO...THE CSTAR-DERIVED INLAND EXTENT APPLICATION DEPICTS A FAIRLY DEEP INLAND PENETRATION THROUGHOUT THE EVE HRS...AT LEAST...WITH A GOOD UPSTREAM CONNECTION TO HURON/NRN LK MI/SUPERIOR...AND ALSO STG 0-1 KM SPEED SHEAR. THIS ALSO SEEMS WELL SUPPORTED BY SIM REFLECTIVITY PRESENTATIONS FROM THE NAM12...LOCAL ARW...AND HRRR MODELS. BOTTOM LN...THINGS APPEAR WELL ON TRACK FOR THE LES WRNG IN NRN ONEIDA...WITH A PD OF VERY HVY SNOW ANTICIPATED...FROM ROUGHLY 22-06Z. GIVEN DEEP MOISTURE...AND EXCELLENT CRYSTAL GROWTH PARAMETERS...2-3"/HR RATES ARE NOT OUT OF THE QUESTION. ELSEWHERE (ONONDAGA/MADISON/SRN ONEIDA)...DESPITE SOME ANTICIPATED WEAKENING LTR TNT...AS THE BAND DROPS SWD...THERE MAY BE ENUF RESIDUAL INTENSITY FOR ADVSY-LVL ACCUMS. WE`LL RE-VISIT THIS SITN EARLY THIS AFTN. ACRS THE TWIN TIERS...SOME CONVECTIVE SHSN ARE LIKELY TO FORM BY MID TO LATE AFTN...AIDED A BIT BY ADVECTION OF MOISTURE FROM LKS ERIE AND SRN MI IN STG WRLY FLOW. OVERALL...THOUGH...THE NATURE OF THEM WILL REMAIN SCTD. AS FOR THE WINDS...THEY`RE LIKELY TO BE AT THEIR PEAK THROUGH ABT 18Z...WITH A SLOW DIMINISHING TREND THEREAFTER...AS JUDGED FROM ISALLOBARIC AND MOMENTUM TRANSFER PROGS. A STEADY OR SLOWLY FALLING TEMP TREND IS WELL HANDLED IN THE GRIDS...SO ONLY VERY MINOR TWEAKS WERE NEEDED. PREV DISC... 620 AM...WILL DROP THE FLOOD WATCH FOR ERN ZONES AS STEADY RAIN IS MOVG OUT. OTRW JUST MINOR NEAR TERM TWEEKS WITH NO SIG CHGS TO FCST. PREV BLO... 450 AM...DROPPED FLOOD WATCH FOR THE CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACK EDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACK EDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAINLY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF THE BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAY SHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... 18Z UPDATE... SNOW HAS MOVED INTO ALL TERMINALS BEHIND COLD FRONT. WITH SCATTERED SNOW SHOWERS, CONDS WILL RANGE FROM VFR TO MVFR THOUGH AN OCCASIONAL IFR CANNOT BE RULED OUT. AS LAKE EFFECT BAND GETS ORGANIZED IFR VSBYS WILL MOVE INTO KRME AFTER 03Z AND KSYR AFTER 09Z. AT KELM AND KITH EXPECT MVFR CONDS TONIGHT WITH FLOW OFF OF LAKE ERIE THOUGH KBGM AND KAVP SHOULD REMAIN LOW VFR. WINDS OUT OF THE SOUTHWEST THIS AFTERNOON AROUND 25KTS WILL GUST TO 30-40KTS. WINDS WILL REMAIN GUSTY NEXT 24 HOURS THOUGH GUSTS WILL LESSEN TO AROUND 25KTS AND GRADUALLY SWITCH AROUND TO A MORE WEST-NORTHWEST DIRECTION. .OUTLOOK... SAT/SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. TUE...MVFR/IFR IN LIGHT SNOW AT ALL TERMINALS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS... NEAR TERM...MLJ SHORT TERM... LONG TERM...MDP/TAC AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1150 AM EST THU JAN 31 2013 .SYNOPSIS... COLDER AIR WORKING INTO THE AREA BEHIND A STRONG COLD FRONT WILL PRODUCE STRONG GUSTY WINDS TODAY...IN ADDITION TO LAKE EFFECT SNOWS DOWNWIND OF LAKES ERIE AND ONTARIO. BELOW NORMAL TEMPERATURES AND SCATTERED SHOW SHOWERS WILL CONTINUE INTO THE WEEKEND...DUE TO A COMBINATION OF LAKE EFFECT SNOW SHOWERS AND WEAK UPPER LEVEL DISTURBANCES. && .NEAR TERM /THROUGH TONIGHT/... 12 NOON UPDATE... WE`VE PUSHED BACK THE START TIME OF THE LES WRNG BY A FEW HRS IN NRN ONEIDA (NOW 21Z). BASED ON THE LATEST KBUF VWP (STILL A 260 FLOW OVER A DEEP LYR)...AND OVERALL RADAR PRESENTATION...WE THINK THE ONSET OF THE +SN IN NRN ONEIDA WILL BE SOMEWHAT DELAYED FROM OUR EARLIER FCST. THE AMTS STILL LOOK REPRESENTATIVE...AS PARAMETERS SEEM FAVORABLE FOR FAIRLY INTENSE RATES...ONCE THE SNOW DOES FINALLY MOVE IN. 10 AM UPDATE... OUR CURRENT FCST IS IN EXCELLENT SHAPE ATTM...SO ONLY COSMETIC CHGS WERE MADE. AS STG CAA CONTS TO FILTER ACRS THE FA LATE THIS MRNG...LES BANDS ARE TRYING TO ORGANIZE OFF BOTH LKS ERIE AND ONT. AS JUDGED FROM THE 12Z RAOBS AT BUF/DTX...THE MIXED LYR EXTENDS UP TO ABT 750 MB...WITH A FAIR MOISTURE SUPPLY UNDERNEATH THE BASE OF THE INVERSION. GIVEN CONTD CYCLONIC FLOW...FURTHER COOLING WITH TIME...AND IF ANYTHING...A DEEPENING OF THE SYNOPTIC MOISTURE THIS AFTN AND EVE...THERE`S NO REASON NOT TO EXPECT THE DVLPMT OF FAIRLY STG LAKE-EFFECT PLUMES OFF BOTH LKS. IN-HOUSE CAPE/SHEAR NOMOGRAM SHOWS ENUF OVER-LAND INSTAB THROUGH THIS EVE (00-03Z)...SO THAT THE BANDS MAY TAKE ON SOMEWHAT OF A CELLULAR APPEARANCE...AT TIMES. HOWEVER...ORGANIZATION IS NOT LIKELY TO BE SERIOUSLY COMPROMISED. ALSO...THE CSTAR-DERIVED INLAND EXTENT APPLICATION DEPICTS A FAIRLY DEEP INLAND PENETRATION THROUGHOUT THE EVE HRS...AT LEAST...WITH A GOOD UPSTREAM CONNECTION TO HURON/NRN LK MI/SUPERIOR...AND ALSO STG 0-1 KM SPEED SHEAR. THIS ALSO SEEMS WELL SUPPORTED BY SIM REFLECTIVITY PRESENTATIONS FROM THE NAM12...LOCAL ARW...AND HRRR MODELS. BOTTOM LN...THINGS APPEAR WELL ON TRACK FOR THE LES WRNG IN NRN ONEIDA...WITH A PD OF VERY HVY SNOW ANTICIPATED...FROM ROUGHLY 22-06Z. GIVEN DEEP MOISTURE...AND EXCELLENT CRYSTAL GROWTH PARAMETERS...2-3"/HR RATES ARE NOT OUT OF THE QUESTION. ELSEWHERE (ONONDAGA/MADISON/SRN ONEIDA)...DESPITE SOME ANTICIPATED WEAKENING LTR TNT...AS THE BAND DROPS SWD...THERE MAY BE ENUF RESIDUAL INTENSITY FOR ADVSY-LVL ACCUMS. WE`LL RE-VISIT THIS SITN EARLY THIS AFTN. ACRS THE TWIN TIERS...SOME CONVECTIVE SHSN ARE LIKELY TO FORM BY MID TO LATE AFTN...AIDED A BIT BY ADVECTION OF MOISTURE FROM LKS ERIE AND SRN MI IN STG WRLY FLOW. OVERALL...THOUGH...THE NATURE OF THEM WILL REMAIN SCTD. AS FOR THE WINDS...THEY`RE LIKELY TO BE AT THEIR PEAK THROUGH ABT 18Z...WITH A SLOW DIMINISHING TREND THEREAFTER...AS JUDGED FROM ISALLOBARIC AND MOMENTUM TRANSFER PROGS. A STEADY OR SLOWLY FALLING TEMP TREND IS WELL HANDLED IN THE GRIDS...SO ONLY VERY MINOR TWEAKS WERE NEEDED. PREV DISC... 620 AM...WILL DROP THE FLOOD WATCH FOR ERN ZONES AS STEADY RAIN IS MOVG OUT. OTRW JUST MINOR NEAR TERM TWEEKS WITH NO SIG CHGS TO FCST. PREV BLO... 450 AM...DROPPED FLOOD WATCH FOR THE CNTRL SRN TIER AND PORTIONS OF THE FINGER LAKES AS BACK EDGE OF STEADIER RAIN HAS EXITED THIS RGN. MAY STILL SEE SOME MINOR FLOODING DUE TO RUNOFF BUT FLS`S HANDLING THAT. CONVECTIVE FNTL LINE PRODUCED WIND GUSTS IN THE 40-50 MPH RECENTLY AT SYR/BGM. SYNOPTIC SCALE WINDS WILL BE INCRSNG RAPIDLY LATER THIS MRNG ALL AREAS. PREV BLO... BACK EDGE OF AREA OF STEADY RAIN AREA MOVING INTO WRN ZONES AS OF 315 AM...CLOSE TO THE PSN OF THE SFC CDFNT...AND WILL CONTINUE IT`S EWD PROGRESS THROUGH THE EARLY MRNG HRS. SOME OF THE RAIN MAY MIX BRIEFLY WITH SNOW BEFORE TAPERING OFF THIS MRNG. FLOOD WATCH REMAINS ON EFFECT...WE HAVE ISSUED SOME FLS`S THUS FAR AND WILL CONTINUE TO MONITOR CAREFULLY. MAIN ISSUE TDA WILL BE THE STRONG WINDS DVLPNG THIS MRNG AND CONTINUING INTO THE AFTN HRS. BASED ON OUR SUSTAINED AND PEAK WIND GRIDS...WE ADDED STEUBEN...YATES AND SENECA COUNTIES INTO THE WARNING. SCATTERED SNOW SHOWERS ARE XPCTD TDA...MAINLY DUE TO LAKE INFLUENCES. WE COULD SEE -SHSN OFF LAKE ERIE ACRS PORTIONS OF THE TWIN TIERS THIS AFTN/EVNG. POTNL FOR 2-4 INCHES ACRS PORTIONS OF WRN STEUBEN TNGT. AFTN SHIFT CAN RE-ASSESS AND DETERMINE IF A LOW END ADVISORY IS NEEDED HERE. AS FOR THE NRN ONEIDA LES EVENT...THIS EVENT APPEARS TO BE SIMILAR TO LAST WEEKS. THE ARW PERFORMED WELL IN THAT CASE...AND THIS MRNG`S RUC ALSO SHOWS GOOD AGREEMENT EARLY ON IN THE PD. IT APPEARS THAT THE BAND WILL NOT MAKE A MOVE INTO NRN ONEIDA UNTIL LATE THIS AFTN...PERSISTING OVER THAT AREA TIL ARND 06Z BEFORE DROPPING SWD AS FLOW BCMS MORE WNWLY. AS THIS OCCURS...MESO MDLS SHOW THE BAND OVER LAKE ONTARIO DROPPING TO A PSN NEAR/ALONG THE SRN SHORE OF LAKE ONTARIO LATE TNGT/TWDS DAYBREAK. THIS IS WHAT OCCURRED WITH THE LAST BAND...AND RESULTED IN RAPID WEAKENING OF THE BAND OVER THE BGM CWA DUE (AT LEAST IN PART) TO THE LOSS OF OVER-LAKE TRAJECTORY. THIS IS ALSO HINTED AT IN THE MESO MDLS FRI MRNG. FOR NOW WE HAVE THE BAND DROPPING SWD INTO ONON/MAD IN THE 09-12Z TIME FRAME...WITH POTNL FOR LOW END ADVISORY ACCUMS MAINLY OVER NW ONON. GIVEN THE NUMEROUS HEADLINES ALREADY IN EFFECT AND THE FACT WE HAVE SOME TIME TO TAKE A CLOSER LOOK AT THIS...WE WILL JUST MENTION THE POTNL IN THE HWO AND LET THE DAY SHIFT ISSUE HEADLINES FOR THIS EVENT IF NEEDED. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A COUPLE OF CLIPPER-TYPE SYSTEMS WILL AFFECT THIS WEEKEND...WITH SCATTERED SNOW SHOWERS. A MORE WDSPRD AREA OF LGT SNOW COULD DVLP IN THE WARM ADVECTION PTRN AHEAD OF THE CLIPPER APRCHNG SAT NGT. IN GNRL...CHC POPS FOR -SHSN AND BLO NORMAL TEMPS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GRIDS WERE ADJUSTED SOME TO ACCOUNT FOR LATEST HPC GUIDANCE AND GFS/ECMWF MODELS. NO BIG CHANGE TO GOING FORECAST OVERALL...BUT I DID UPGRADE POPS INTO LIKELY CATEGORY FOR CENTRAL NY AND AT LEAST HIGHER CHANCE FOR NORTHEAST PA SUNDAY WITH FAIR AGREEMENT ON BEING INVOLVED IN MERGER BETWEEN DEVELOPING COASTAL LOW AND INCOMING NORTHERN STREAM SYSTEM/CLIPPER. COULD EASILY RESULT IN LIGHT COATING OF SNOW. ANOTHER WEAK CLIPPER CONTINUES TO LOOK POSSIBLE MONDAY NIGHT/TUESDAY. PREVIOUS DISCUSSION... FOLLOWED HPC GUIDANCE. MODELS ARE SIMILAR WITH NO LARGE STORMS. REMAIN UNDER A NORTHEAST US UPPER LEVEL TROF. SEASONABLE WEATHER WITH WEAK LOW PRESSURE SYSTEMS FOLLOWED BY LAKE EFFECT. ALL PRECIP WILL BE SNOW WITH HIGHS AROUND 30 AND LOWS IN THE TEENS. THE WEAK SYSTEMS GO THROUGH SUNDAY AND MONDAY NIGHT...WITH LAKE EFFECT ON THE OTHER DAYS. COULD BE A 12 HOUR DRY BREAK BETWEEN SYSTEMS WITH WEAK HIGH PRESSURE MON AFTN. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... 12Z UPDATE... STRONG COLD FRONT IS JUST FINISHING ITS BLAST THROUGH THE AREA...TAKING THE STEADIER RAIN SHOWERS WITH IT. WINDS WILL HAVE A MUCH EASIER TIME MIXING DOWN IN THE COLD AIR BEHIND THE FRONT...ALLOWING WESTERLY GUSTS FREQUENTLY IN THE 30-40 KT RANGE. GUSTS AT KSYR AND PERHAPS KRME WILL EVEN TOP OUT AROUND 35-45 KTS AT TIMES TODAY. EXPECTING SCT-BKN CLOUD DECK WITH SCT -SHSN AND MVFR CIG FOR SOME TERMINALS. THOUGH GENERALLY VFR TO MVFR IN TAFS TODAY WITH THE SNOW FLURRIES...SOME TERMINALS WILL HAVE TO WATCH FOR BRIEF SURPRISE IFR VIS FROM A HEAVIER LAKE EFFECT SNOW SHOWER. THE MAIN LAKE ONTARIO SNOW BAND WILL AT FIRST DEVELOP NORTH OF THE AREA THIS AFTERNOON...BUT SHOULD EDGE SOUTH ENOUGH TO INVOLVE KRME IN OCCASIONAL IFR VIS AFTER 03Z...AND BY 09Z ONWARD FOR KSYR. .OUTLOOK... FRI THRU SAT NGT...MVFR-IFR FROM LAKE -SHSN IN CENTRAL NY. SUN...A COLD FRONT WITH POSSIBLE MVFR AND IFR SNOW SUN NGT-MON...MORE MVFR/IFR LAKE -SHSN MAINLY CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ038>040-043- 044-047-048-072. NY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ023>025-044- 045-055-056-062. HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ009- 015>018-022-036-037-046-057. LAKE EFFECT SNOW WARNING FROM 4 PM THIS AFTERNOON TO 7 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS... NEAR TERM...MLJ SHORT TERM... LONG TERM...MDP/TAC AVIATION...MDP
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1208 PM EST THU JAN 31 2013 .SYNOPSIS... COOL HIGH PRESSURE WILL BUILD IN FROM THE WEST TODAY...WITH BELOW NORMAL TEMPERATURES EXPECTED. IT WILL BE BREEZY TODAY... ALTHOUGH WINDS WILL NOT BE AS STRONG AS LAST NIGHT. A SERIES OF DRY COLD FRONTS WILL MOVE ACROSS THE AREA. THE FIRST FRONT WILL CROSS THE AREA FRIDAY FOLLOWED BY ANOTHER ON SUNDAY AND YET ANOTHER ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 AM THURSDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. TEMPERATURES ARE SLOW TO RISE AS EXPECTED BUT ARE FOLLOWING THE HOURLY CURVE DERIVED FROM A NAM/RUC BLEND WITHIN +/-1 DEGREE. NO CHANGES ARE NEEDED. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS... THE SEASONS HAVE CHANGED YET AGAIN WITH YESTERDAY`S SPRING-LIKE WEATHER REPLACED BY A RETURN TO WINTER TODAY. COLD ADVECTION ON WESTERLY WINDS BEHIND LAST NIGHT`S STRONG COLD FRONT WILL ALMOST PERFECTLY BALANCE NEARLY FULL SUNSHINE TODAY AND TEMPERATURES WILL STRUGGLE JUST TO RISE A FEW DEGREES BY AFTERNOON...REACHING 53-56 DEGREES AREAWIDE. THE 12Z GSO SOUNDING WAS BEST SIMULATED BY THE 12Z NAM AND RUC MODELS...AND THESE ARE THE TWO MODELS I BLENDED FOR MY UPDATED FORECAST TODAY. DOWNWARD REVISIONS HAVE BEEN MADE TO DEWPOINT FORECASTS FOR THE AFTERNOON HOURS WITH LOWER 20S DEWPOINTS EXPECTED TO MIX DOWN FROM A RESERVOIR OF VERY DRY AIR ALOFT. PRECIPITABLE WATER VALUES TODAY SHOULD RANGE FROM 0.20 TO 0.25 INCHES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...SHORTWAVE ROUNDING BASE OF MID LEVEL TROUGH EARLY FRI HELPS DRIVE A REINFORCING SHOT OF COLD AIR INTO THE REGION. DRY COLD FRONT PUSHES OFFSHORE BY MIDDAY WITH A PERIOD OF BRIEF BUT STRONG COLD ADVECTION ENDING LATE FRI NIGHT. TEMP DROP WILL BE SIGNIFICANT WITH GUIDANCE SHOWING 850 TEMPS DECREASING BY AS MUCH AS 10C IN SOME PLACES IN UNDER 12 HOURS. DEEP WEST TO NORTHWEST FLOW FRI INTO FRI NIGHT HELPS KEEP SKIES CLEAR. PATTERN BECOMES LESS AMPLIFIED AND MORE PROGRESSIVE LATE FRI NIGHT...SHUTTING OFF COLD ADVECTION. MORE PROGRESSIVE EVOLUTION OF MID LEVEL PATTERN HELPS MOVE CENTER OF SURFACE RIDGE AXIS OVER THE REGION FOR SAT MORNING...ALLOWING FOR SOME RADIATIONAL COOLING. DO NOT ANTICIPATE EFFECT TO BE VERY STRONG BUT TYPICAL COLD SPOTS WILL FLIRT WITH TEENS FOR LOWS. HIGHS FRI WILL STRUGGLE TO REACH CLIMO WHILE LOWS WILL DROP INTO THE LOW TO MID 20S IN MOST AREAS SAT MORNING. SURFACE RIDGE AXIS SHIFTS OFFSHORE SAT WITH WEAK RETURN FLOW SETTING UP FOR THE END OF THE PERIOD. ALOFT ANOTHER SHORTWAVE HELPS AMPLIFY THE MID LEVEL PATTERN...RESULTING IN A SHORT PERIOD OF DEEP WEST-SOUTHWEST FLOW AHEAD OF ANOTHER COLD FRONT MOVING INTO THE REGION AS THE PERIOD ENDS. ANTICIPATE AN INCREASE IN MID AND UPPER LEVEL CLOUD ASSOCIATED WITH THIS WAVE BUT DURATION OF RETURN FLOW IS NOT ENOUGH TO BRING SIGNIFICANT MOISTURE BACK INTO THE REGION BEFORE THE FRONT PASSES. ALTHOUGH SOME GUIDANCE IS POINTING TO SOME LIGHT ISOLATED PRECIP EARLY SUN MORNING DO NOT THINK THIS WILL BE THE CASE. WILL MAINTAIN A POP FORECAST AROUND 10 SAT NIGHT. TEMPERATURES REMAIN BELOW CLIMO SAT BUT END UP MUCH CLOSER TO CLIMO SAT NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 3 AM THURSDAY...A RATHER REPETITIVE PATTERN FOR THE EXTENDED AS AREAS OF HIGH PRESSURE PUSH OFFSHORE AHEAD OF A SERIES OF WEAK COLD FRONTS. FIRST COLD FRONT WILL CROSS THE AREA VERY EARLY SUNDAY MORNING. LIMITED FORCING COMBINED WITH ONLY MARGINAL PWATS SUGGESTS FROPA WILL BE DRY...AND ONLY ACT TO REINFORCE THE COOL AIR. HOWEVER...ANY WEAK CAA REMAINS WELL DISPLACED BEHIND THE FRONT...SO SUNDAY WILL END UP BEING WARMER THAN SATURDAY...ALTHOUGH BOTH DAYS WILL BE AROUND TO SLIGHTLY BELOW CLIMO. ANOTHER LARGE BUT WEAK AREA OF HIGH PRESSURE BUILDS DOWN FROM THE NW LATE SUNDAY AND PERSISTS INTO TUESDAY WHILE SLOWLY DRIFTING ACROSS THE REGION. THIS CONTINUES THE COOL AND DRY WEATHER WITH NEAR TO SLIGHTLY-BELOW SEASONABLE TEMPS. THIS HIGH PRESSURE THEN DRIFTS OFFSHORE TUESDAY AHEAD OF ANOTHER COLD FRONT PROGGED TO CROSS THE AREA LATE IN THE DAY. GUIDANCE SHOWING CONSIDERABLE AMPLITUDE DIFFERENCES IN THE TROUGH DRIVING THIS FRONT WHICH WILL HAVE SIGNIFICANT IMPACT ON PRECIP POTENTIAL. FOR NOW WILL KEEP INHERITED SCHC/SILENT POP FOR D6 SINCE BENEFICIAL CHANGES CANNOT BE MADE AT THIS TIME. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD THOUGH AHEAD OF THE COLD FRONT...WITH TEMPS RETURNING TO BELOW CLIMO FOR WEDNESDAY AS ANOTHER AREA OF HIGH PRESSURE RIDGES DOWN FROM THE NW. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 18Z...VFR WITH CLEAR SKIES THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL PRODUCE WSW-W WINDS 15-25 KNOTS WITH SPEEDS GRADUALLY DIMINISHING. VFR THIS EVENING AND OVERNIGHT WITH WSW WINDS 6-12 KNOTS. ANOTHER COLD FRONT WILL TRAVERSE THE TERMINALS AFTER SUNRISE. MAINLY SCATTERED VFR LEVEL LOW CLOUDS EXPECTED AS WINDS SHIFT TO THE WNW GUSTING TO AROUND 25 KNOTS. EXTENDED OUTLOOK...VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM THURSDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. WINDS OUT AT FRYING PAN SHOALS BUOY ARE GUSTING TO 33 KNOTS ON THE LATEST OBSERVATION...AND GUSTS AT THE VARIOUS PIERS AND BEACH OBSERVATIONS FINALLY ARE BELOW 30 KNOTS. SEAS CONTINUE TO DIMINISH AS WELL. THE SMALL CRAFT ADVISORY WILL REMAIN POSTED FOR THE ONGOING WINDS...AND FOR THE ANTICIPATION OF A RENEWED SURGE OF NORTHWEST WINDS FRIDAY MORNING BEHIND A SECOND COLD FRONT. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS... EARLIER BLOWOUT TIDE CONDITIONS HAVE ABATED. WATER LEVELS AS MEASURED AT THE OFFICIAL NOS (NATIONAL OCEAN SERVICE) TIDE GAUGES REACHED -1.92 FT MLLW AT WRIGHTSVILLE BEACH... AND -1.50 FT MLLW AT MYRTLE BEACH. FOR THE NEXT LOW TIDE JUST AFTER 4 PM...WESTERLY WINDS SHOULD BE DIMINISHING WITH LESS IMPACT ON COASTAL WATER LEVELS. OTHERWISE...WEST WINDS AROUND 30 KNOTS WITH FREQUENT GALE-FORCE GUSTS ARE STILL OCCURRING ACROSS THE AREA THIS MORNING. I WISH THE GALE WARNING WERE STILL UP AS GUSTS AT THE FRYING PAN SHOALS BUOY CONTINUE TO ECLIPSE 40 KNOTS...AND WITH 12 FOOT SEAS I AM FAIRLY CERTAIN SUSTAINED GALE-FORCE WINDS ARE OCCURRING BEYOND 15 MILES FROM SHORE. THESE VERY STRONG WINDS SHOULD BEGIN TO ABATE OVER THE NEXT 2 HOURS AS HIGH PRESSURE OVER SOUTHERN LOUISIANA NOSES TOWARD THE CAROLINAS AND OUR PRESSURE GRADIENT BEGINS TO WEAKEN. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...SMALL CRAFT ADVISORY CONTINUES INTO FRI BEFORE PASSAGE OF COLD FRONT AND DEVELOPMENT OF OFFSHORE FLOW PUSHES 6 FT SEAS BEYOND 20 NM. STRONG BUT BRIEF COLD ADVECTION DURING THE SECOND HALF OF FRI INTO FRI NIGHT MAY REQUIRE A PERIOD OF SCEC HEADLINES. HIGH PRESSURE BUILDS IN FROM THE WEST LATE FRI NIGHT THEN SHIFTS OVER THE WATERS DURING SAT. WEAKENING GRADIENT ALLOWS WIND SPEEDS TO DROP FROM A SOLID 20 KT FRI TO UNDER 10 KT BY SAT MORNING. RETURN FLOW STARTS TO DEVELOPING SAT AFTERNOON AS HIGH PRESSURE SLIDES EAST OF THE WATERS. GRADIENT BECOMES PINCHED AHEAD OF NEXT COLD FRONT...WITH SOUTHWEST WINDS INCREASING TO 15 KT AS THE PERIOD ENDS. SEAS SUBSIDE DURING FRI...DROPPING FROM 4 TO 7 FT AT THE START OF THE PERIOD TO 3 TO 4 FT FRI EVENING. SEAS FALL FURTHER...CLOSE TO 2 FT...EARLY SAT BEFORE STARTING TO BUILD BACK CLOSER TO 3 TO 4 FT LATE IN THE PERIOD AS SOUTHWEST WINDS INCREASE. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 3 AM THURSDAY...A COLD FRONT WILL CROSS THE WATERS SUNDAY... TURNING WINDS TO THE W/NW AT 10-15 KTS ON SUNDAY BEFORE SLOWLY EASING TO LIGHT AND VARIABLE AGAIN MONDAY AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. SEAS WILL BE PRIMARILY WIND-DRIVEN THROUGH THE PERIOD...INCREASING FOR A SHORT TIME SUNDAY UP TO 2-4 FT... THEN DECREASING TO 1 TO 2 FT MONDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST FRIDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...TRA SHORT TERM...III LONG TERM...JDW AVIATION...MRR
AREA FORECAST DISCUSSION
NWS PORTLAND OR
843 AM PST THU JAN 31 2013 .SYNOPSIS...ONE LAST SYSTEM MOVING OVER THE TOP OF AN OFFSHORE HIGH PRESSURE WILL BRING SOME LIGHT RAIN TO THE NORTHERN TIER TODAY. STRENGTHENING HIGH PRESSURE WILL BRING DRY WEATHER FOR AT LEAST FRIDAY AND SATURDAY...THOUGH THERE WILL BE PLENTY OF LOW CLOUDS AND FOG ACROSS THE INTERIOR VALLEYS. EAST WINDS WILL INCREASE ACROSS THE WESTERN COLUMBIA RIVER GORGE LATE FRIDAY LIKELY CAUSING THE PORTLAND METRO AREA TO CLEAR THOUGH. SYSTEMS LATE THIS WEEKEND AND EARLY NEXT WEEK APPEAR WEAK...WITH BETTER CHANCES OF PRECIPITATION AROUND THE MIDDLE OF NEXT WEEK. && .SHORT TERM...DOPPLER RADAR MOSAIC SHOWS A BAND OF LIGHT RAIN MOVING INTO SOUTHWEST WASHINGTON AND EXTREME NORTHWESTERN OREGON. THIS RAIN IS ASSOCIATED WITH AN AREA OF ISENTROPIC LIFT ACCOMPANYING A WEAK FRONT PUSHING SOUTHEASTWARD. AS THIS FRONT DETACHES FROM ITS PARENT UPPER LEVEL TROUGH OVER BRITISH COLUMBIA...EXPECT IT TO STALL AND WEAKEN IN THE VICINITY OF THE COLUMBIA RIVER THIS AFTERNOON AND TONIGHT...AS IT BECOMES ORIENTED MORE LATITUDINALLY. THE CURRENT PRECIPITATION BAND IS A LITTLE MORE EXTENSIVE AND ARRIVING EARLIER THAN MOST MODELS WOULD SEEM TO SUGGEST...EVEN THE SHORT TERM MODELS. THE LATEST HRRR SUGGESTS A SHOWER OR TWO WILL BE POSSIBLE ACROSS THE PORTLAND METRO AREA LATER THIS AFTERNOON AND GIVEN THE SOUTHWARD EXTENT OF PRECIPITATION ON RADAR...THIS IDEA SEEMS PLAUSIBLE. AS A RESULT OF THE ABOVE...POPS WERE INCREASED FOR TODAY...AND GRIDS WERE SPLIT INTO THREE HOURS TO ATTEMPT TO REFLECT THE LATEST TIMING AND TRENDS IN RAIN CHANCES. THE OTHER PROBLEM CHILD THIS MORNING ARE AREAS OF FOG ACROSS THE PORTLAND METRO AREA. GIVEN PORTIONS OF THE METRO AREA...SUCH AS DOWNTOWN...REMAIN FOG FREE...WILL CONTINUE TO HANDLE THE FOG PROBLEM WITH NOWCASTS. GIVEN THE LOW SUN ANGLE AND LIGHT LOW LEVEL FLOW...I DID EXPAND THE FOG MENTION IN THE GRIDS UNTIL 1 PM AS IT WILL LIKELY BE SLOW TO LIFT AND MIX OUT. SKY COVER GRIDS WERE TWEAKED AS WELL FURTHER SOUTH AS AREA CAMS AND THE FIRST VISIBLE SATELLITE IMAGES OF THE DAY INDICATE MOSTLY SUNNY TO PARTLY CLOUDY SKIES EXIST ACROSS THE CENTRAL OREGON COAST AND THE CENTRAL OREGON CASCADES. /NEUMAN .LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...THE UPPER LEVEL RIDGE IN PLACE TO START THE WEEKEND BEGINS TO BREAK DOWN SLOWLY TOWARD LATE SATURDAY AS A WEAK BOUNDARY APPROACHES THE AREA. THIS BOUNDARY WILL AT THE LEAST BRING INCREASING CLOUDS TO THE AREA BY SUNDAY...BUT IT WILL BE SHEARING AND SPLITTING...SO EXPECT RAIN CHANCES TO BE ON THE LOW END. A QUICK MOVING BUT STRONGER FRONTAL SYSTEM WILL THEN APPROACH THE COAST LATE SUNDAY INTO MONDAY. THIS SYSTEM SEEMS TO FURTHER BREAK DOWN THE RIDGE...BUT MODELS DISAGREE ON HOW MUCH MOISTURE IT PUSHES INLAND...BEFORE THE RIDGE REBOUNDS ON MONDAY AFTERNOON. ANOTHER FRONTAL SYSTEM IS SHOWN TO SWING THROUGH THE AREA LATER IN THE DAY TUESDAY OR TUESDAY EVENING. A COLD UPPER TROUGH WILL THEN MOVE THROUGH FOR THE LATTER HALF OF THE WEEK. KMD/BROWN && .AVIATION...FLIGHT CONDITIONS REMAIN VARIABLE THIS MORNING... RANGING ANYWHERE FROM LIFR TO VFR CATEGORY. MOIST LOW LEVELS IN A LIGHT ONSHORE FLOW ARE LIKELY TO KEEP A VARIETY OF CONDITIONS ACROSS THE AREA. OVERALL TREND IN THE AFTERNOON IS LIKELY TO BE FOR SLOW IMPROVEMENT TO PREDOMINANTLY MVFR IN THE NORTH AND AND VFR CATEGORY IN THE SOUTH. EXPECT A RETURN TO IFR CONDITIONS ACROSS MUCH OF THE INTERIOR TONIGHT WITH A MIX OF MVFR AND IFR CONDITIONS ALONG THE COAST. KPDX AND APPROACHES...IFR AND LIFR CONDITIONS WILL CONTINUE THIS MORNING. CONDITIONS WILL LIKELY IMPROVE TO MVFR AFTER 20Z TODAY. IFR CONDITIONS ARE LIKELY TO RE-DEVELOP AFTER 08Z TONIGHT AS THE AIRMASS STABILIZES. && .MARINE...FAIRLY QUIET NEXT COUPLE OF DAYS AS A HIGH PRES SYSTEM IS LIKELY TO KEEP WINDS BELOW SMALL CRAFT CRITERIA THROUGH THE WEEKEND. A LONG PERIOD SWELL OUT OF THE W IS EXPECTED TO BEGIN SHOWING UP FRI...AND ULTIMATELY RAISE SEAS ABOVE 10 FT ON SAT AND SUN. ALTHOUGH THE OFFSHORE WAVE HEIGHTS ARE EXPECTED TO PEAK IN THE 10 TO 12 FT RANGE SAT AND SUN...THE LONG PERIODS MAY PUSH BREAKERS AS HIGH AS THE 18 TO 20 FT RANGE. && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. PZ...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 10 AM PST THIS MORNING. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 5 PM THIS AFTERNOON TO 9 PM PST THIS EVENING. && $$ MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.