Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/27/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
340 PM MST FRI JAN 25 2013 .SHORT TERM...MOUNTAIN WEB CAMS SHOWING ISOLATED LIGHT SNOW SHOWERS ACROSS THE HIGHER PEAKS ACROSS SUMMIT AND GRAND COUNTIES. PERHAPS SOME LIGHT SNOW SHOWERS ALSO OCCURRING OVER THE GORE AND PARK MOUNTAINS OF WESTERN JACKSON COUNTY. OTHERWISE...MAINLY MOSTLY CLOUDY SKIES OVER THE REGION WITH WESTERLY FLOW ALOFT. MODELS SHOW THE WESTERLY FLOW ALOFT PERSISTING THROUGH THE EVENING...GRADUALLY BECOMING SOUTHWEST OVERNIGHT AS AN UPPER TROUGH MOVES INTO THE GREAT BASIN. LATEST RAP CROSS SECTIONS SHOW A GRADUAL LOWERING OF THE MOISTURE ACROSS THE MOUNTAINS DURING THE EVENING...WITH THE DEEPER MOISTURE AFTER MIDNIGHT. BOTH NAM AND GFS CROSS SECTIONS INDICATE LESS MOISTURE. BASED ON LATEST SATELLITE LOOPS...NOT ALOT OF DEEPER MOISTURE UPSTREAM OVER UTAH AND ARIZONA...SO THE RAP MOISTURE COULD BE A BIT OVERDONE. AT ANY RATE...SHOULD GRADUALLY SEE SOME LOWERING OF CLOUDS THROUGH THE EVENING ACROSS THE MOUNTAINS. MODELS SHOW LAPSE RATES OF AROUND 6 C/KM ALONG...SO SNOW CHANCES SHOULD BEGIN TO INCREASE WITH THE BEST ACROSS ZONE 31 AND PORTIONS OF 34 AFTER MIDNIGHT. AMOUNTS SHOULD REMAIN LIGHT...AROUND AN INCH OR LESS. DRY CONDITIONS TO CONTINUE ACROSS PLAINS. OVERNIGHT TEMPERATURES TO BE FAIRLY MILD GIVEN CLOUD COVER AND LACK OF COLD AIR ADVECTION. ON SATURDAY...FLOW TO BECOME SOUTHWEST WHICH SHOULD ALLOW FOR MORE MOISTURE TO STREAM OVER THE AREA. MODELS SHOW AN INCREASE IN MID LEVEL QG ASCENT AHEAD OF AN APPROACHING SHORTWAVE. THIS ASCENT COMBINED WITH MODEST LAPSE RATES SHOULD HELP TO IMPROVE SNOW CHANCES ACROSS THE MOUTAINS. SOUTHWEST FLOW TO CONTINUE TO FAVOR ZONE 31 AND WILL HAVE THE HIGHER POPS THERE. DESPITE THE MODEST LAPSE RATES AND INCREASING ASCENT...SNOW AMOUNTS SHOULD REMAIN FAIRLY LIGHT WITH UP TO TWO INCHES ALONG SOUTHWEST FACING SLOPES. THERE MAY BE SOME ALONG THE FOOTHILLS DURING THE AFTERNOON AS THE LIFT MOVES OVER THE AREA. AND WILL KEEP THE SLIGHT CHANCE GOING. TEMPERATURES THERE LOOK WARM ENOUGH FOR THE PRECIP TO BE RAIN. AS FOR PLAINS. LOW LEVELS TOO DRY FOR ANY MENTION OF PRECIP...MAYBE SOME VIRGA IN AND NEAR THE FOOTHILLS. CLOUD COVER TO KEEP TEMPERATURES FAIRLY COOL ACROSS THE PLAINS...WITH HIGHS IN THE 50S. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY...UNSETTLED WEATHER PATTERN THOUGH THE PERIOD WITH SNOW POSSIBLE ACROSS THE HIGH COUNTRY THIS WEEKEND THROUGH EARLY NEXT WEEK. MODEL CONFIDENCE IS LOW AT THIS TIME WITH FORECAST UNCERTAINTIES ESPECIALLY EAST OF THE MOUNTAINS DAYS 5 AND 6. SATURDAY NIGHT THROUGH SUNDAY MORNING...WEAK SHORT WAVE EJECTS OUT OF THE DESERT SOUTHWEST INTO COLORADO LATE SATURDAY. A MOIST SOUTHWESTERLY FLOW ALOFT OVER COLORADO WILL BRING INCREASING CHANCES OF SNOW TO THE HIGH COUNTRY AS WELL AS A FEW LIGHT SHOWERS TO THE PLAINS SATURDAY NIGHT INTO SUNDAY MORNING. THE SNOW SHOULD BE LIGHT DUE TO POOR OROGRAPHICS AND WARM ADVECTION AT MID LEVELS. THE RHEA- THALER OROGRAPHIC SNOW MODEL SHOWS UP TO 2 INCHES OF SNOW IN THE MOUNTAINS DURING THIS PERIOD. SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON...MOIST SOUTHWESTERLY FLOW ALOFT CONTINUES OVER COLORADO AS AN UPPER LEVEL STORM SYTEM DEVELOPS OVER THE WESTERN UNITED STATES. THIS PATTERN WILL BRING CONTINUED LIGHT SNOW TO THE HIGH COUNTRY THROUGH THE PERIOD...WITH DRY WEATHER EXPECTED EAST OF THE MOUNTAINS. MONDAY EVENING THROUGH FRIDAY...MODEL DISCRENCIES CONTINUE WITH THE GFS AND ECMWF HAVING VERY DIFFERENT SOLUTIONS DURING THIS PERIOD. THE OPERATIONAL GFS RUN CONTINUES TO SHOW A LARGE OPEN WAVE TROUGH MOVING ACROSS THE ROCKY MOUNTAIN REGION EARLY NEXT WEEK. THE ECMWF SHOWS THE ENERGY FROM THE STORM SYSTEM SPLITTING...WITH PART OF THE ENERGY DIGGING INTO THE DESERT SOUTHWEST WITH THE OTHER PART GETTING CAUGHT UP IN THE NORTHERN BRANCH OF THE JET STREAM OVER THE NORTHERN PLAINS STATES. IN ADDITION...OVER HALF OF THE GFS AND CANADIAN ENSEMBLES HAVE A SIMILAR PATTERN TO THE ECMWF. BOTH SOLUTIONS WOULD BRING COLDER TEMPERATURES TO NORTH CENTRAL AND NORTHEASTERN COLORADO EARLY NEXT WEEK. HOWEVER...THE SNOWFALL POTENTIAL WITH THE SOLUTIONS WOULD BE VASTLY DIFFERENT. THE GFS AND THE ECMWF HAVE A COLD FRONT MOVING INTO NORTHEASTERN COLORADO MONDAY NIGHT...WITH UPSLOPE FLOW DEVELOPING. THE GFS DEVELOPS A DEEPER UPLOPE FLOW WITH A MORE PROLONGED PERIOD OF SNOWFALL ALONG THE FRONT RANGE AND EASTERN PLAINS...WHILE THE ECMWF IS MORE SHALLOW AND ONLY PRODUCES A QUICK SHOT OF LIGHTER SNOWFALL. FOR NOW I AM INCLINED TO FAVOR THE ECMWF. THEREFORE...I HAVE MADE LITTLE CHANGES FOR THIS PERIOD AND HAVE ONLY RAISED POPS TO THE CHANCE CATEGORY OVER THE PLAINS MONDAY NIGHT INTO TUESDAY MORNING. MODELS SHOW A MOIST NORTHWEST FLOW ALOFT DEVELOPING OVER COLORADO BY NEXT WEDNESDAY AS THE UPPER LEVEL STORM SYSTEM MOVES EAST OF COLORADO. AS A RESULT...THE CHANCE OF SNOW MAY CONTINUE ACROSS THE HIGH COUNTRY THROUGH THE END OF THE WORK WEEK. && .AVIATION...NORTHEAST WINDS PREVAILING ACROSS DEN AND APA...MORE NORTHERLY AT BJC. WINDS TO WEAKEN DURING THE EVENING...BECOMING SOUTHWEST AROUND 03Z AS DRAINAGE PATTERN DEVELOPS. GRADUAL INCREASE IN MID AND HIGH LEVEL CLOUDS...WITH CEILINGS REMAING ABOVE 10000 FEET. ON SATURDAY...WINDS TO REMAIN SOUTHERLY THROUGH 18Z...PERHAPS MORE SOUTHEAST AT DEN AND APA. SLIGHT CHANCE OF CEILINGS OF AROUND 7000 FEET AGL DEVELOPING DURING THE AFTERNOON WIT PERHAPS SOME VIRGA. FOR NOW WILL LEAVE OUT OF THE TAFS. VFR TO CONTINUE. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....KALINA AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST FRI JAN 25 2013 .UPDATE... && .SHORT TERM...MOUNTAIN WEB CAMS INDICATING MOST OF THE SNOW HAS COME TO AN END...THOUGH SOME AREAS OF SNOW STILL LINGERING ACROSS THE HIGHER RIDGES. LATEST RAP SHOWED THIS TREND OF ENDING THE SNOW BY 18Z AS THE MOISTURE DEPTH DECREASES. STILL APPEARS SOME POCKETS OF LOW LEVEL MOISTURE WILL PERSIST THROUGH THE AFTERNOON...MAINLY ALONG WEST FACING SLOPES. LATEST UPDATE INCLUDED LOW POPS ACROSS THE MOUNTAINS THROUGH THE AFTERNOON...WHICH SEEMS REASONABLE. FOR THIS EVENING INTO TONIGHT...RAP INCREASES THE MOISTURE ONCE AGAIN AS THE FLOW ALOFT BECOMES SOUTHWEST. THERE IS SOME INCREASE IN MID LEVEL QG ASCENT WITH LAPSE RATES AROUND 5-6 C/KM. OTHER MODELS LESS EXCITED WITH SNOW CHANCES. THOUGH THE OROGRAPHICS NOT FAVORABLE FOR SNOWFALL...WILL UP THE MOUNTAIN POPS A BIT THIS EVENING AND TONIGHT BASED ON THE ASCENT AND LAPSE RATES. WILL WAIT FOR LATER DATA FOR ANY FURTHER POP INCREASE. WHATEVER SNOW THAT FALLS SHOULD BE LIGHT. REST OF FORECASTS SEEM ON TRACK AT THIS POINT. TEMPERATURES TO BE RATHER "BALMY` IN THE KREMMLING AREA TODAY... .AVIATION...LATEST RAP AND HRRR INDICATING SOME SORT OF MESOCYCLONE DEVELOPING IN THE DENVER AREA DURING THE AFTERNOON WHICH COULD TURN THE WINDS AND DEN AND APA TO THE NORTHEAST. WILL TREND THE TAFS IN THAT DIRECTION AFTER 22Z. REST OF TAF TRENDS LOOK ON TRACK. && .PREV DISCUSSION... /ISSUED 412 AM MST FRI JAN 25 2013/ SHORT TERM...LAST NIGHTS WEAK WAVE IS MOVING OUT OF COLORADO WITH SOME DRYING BEHIND IT. FLOW ALOFT BECOMING MORE WESTERLY AGAIN AND DECREASING. THERE IS STILL A LITTLE WIND IN THE MOUNTAINS...BUT NOT AS MUCH AS THE LAST COUPLE OF DAYS. HUMIDITIES ALSO HIGHER TODAY AS ALL THAT DRY AIR HAS FINALLY BEEN DISPLACED. HIGH CLOUDS WILL BE COMING AND GOING...EXPECT AN INCREASE AGAIN THIS AFTERNOON AS THE MORE WESTERLY FLOW BRINGS THE EDGE BACK OVER US...THEN SOME DECREASE AGAIN OVERNIGHT. MEANWHILE THE LOWER CLOUDS THAT HAVE PUSHED OVER GRAND AND SUMMIT COUNTIES FROM THE GREAT BASIN SHOULD BE PERSISTENT. THE BIGGEST CHANGE IS THAT THE COLD POOL IN GRAND COUNTY IS FINALLY GONE...SO WHILE THE AIRMASS WILL STILL BE RATHER STAGNANT HERE IT IS A MILDER AND MOIST ONE. THE BIGGEST CHANGE THIS MORNING HAS BEEN TO DEAL WITH THE TEMPERATURES IN THAT AREA...WENT WITH A MOS BLEND WHICH IS UP TO 30 DEGREES WARMER THAN WHAT WE HAD AT KREMMLING. ELSEWHERE THE PREVIOUS FORECAST IS STILL IN GOOD SHAPE. LONG TERM...SATURDAY AND SATURDAY NIGHT...A MOIST SOUTHWESTERLY FLOW ALOFT WILL BE OVER WESTERN COLORADO. A WEAK SHORT WAVE TROUGH EMBEDDED IN THE FLOW ALOFT IS EXPECTED TO MOVE ACROSS THE STATE SATURDAY NIGHT. QG ASCENT GENERATED BY THE MDLS IS WEAK BUT THERE IS FAVORABLE MID LEVEL INSTBY WITH 700-500 LAPSE RATES AROUND 7.5C/KM. SWLY FLOW AT 700 MB WILL FAVOR ZONE 31 THE MOST. AS A RESULT...EXPECT ONLY LIGHT ACCUMULATIONS ALONG WEST AND SOUTHWEST FACING SLOPES. ALTHOUGH MDLS GENERATE A LITTLE BIT OF QPF SURVIVING AS THE TROUGH AXIS MOVE ACROSS THE EASTERN PLAINS OF COLORADO LATE SATURDAY NIGHT...SUSPECT MORE VIRGA VS ISOLD SHOWER ACTIVITY. SUNDAY AND SUNDAY NIGHT...A SHORT WAVE RIDGE WILL ALLOW FOR A DECREASING CHANCE OF SNOW IN THE MOUNTAINS WITH MID LEVEL WARM AIR ADVECTION STABILIZING THE AIRMASS. FLOW ALOFT WILL REMAIN SOUTHWESTERLY AHEAD OF THE NEXT SYSTEM DROPPING OUT OF THE PACIFIC NORTHWEST. MONDAY THROUGH TUESDAY...TIMING AND TRACK DISCREPANCIES CONTINUE TO PERSIST IN THE MDLS REGARDING THE NEXT SYSTEM. WILL MAKE LITTLE IF ANY ADJUSTMENT IN THIS PERIOD...CARRYING CHC POPS IN THE MTNS WITH SLGT CHC POPS OVER THE NORTHEAST PLAINS. THE TROF AXIS IS EXPECTED TO SHIFT TO THE EAST MONDAY EVENING...WITH COLD AIR ADVECTION AND MORE FAVORABLE OROGRAPHIC DEVELOPING AS THE RIDGETOP WINDS BECOME NORTHWESTERLY. COULD SEE SOME BANDED PCPN DEVELOPING OVER THE CWFA ON MONDAY AS A 120+ KT UPPER JET AHEAD OF THE NEXT SYSTEM TRAVERSES SOUTHEAST ACROSS THE STATE. THE STRONGEST QG ASCENT IS PROGGED TO PASS TO THE WEST AND SOUTH OF COLORADO...WITH MORE SUBSIDENCE EXPECTED OVER THE CWFA ON TUESDAY. WEDNESDAY THROUGH THURSDAY...A DRY AND STABLE NORTHWESTERLY FLOW ALOFT WILL BE OVER THE STATE...WITH A GRADUAL TEMPERATURE RECOVERY BY MID-WEEK. AVIATION...VFR CONDITIONS THROUGH TONIGHT. WINDS WILL GENERALLY BE LIGHT SOUTHEAST TODAY AT KDEN/KAPA...LIKELY BECOMING NORTHEAST OR VARIABLE FOR A FEW HOURS LATE IN THE AFTERNOON. KBJC MAY SEE A PERIOD OF WEST WINDS THIS MORNING...BUT SHOULD SWITCH TO AN EAST OR NORTHEAST DIRECTION THIS AFTERNOON. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....COOPER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
938 PM EST Sat Jan 26 2013 .NEAR TERM [Tonight]... The 00 UTC surface analysis shows a frontal boundary across the forecast area. This boundary separates a more moist tropical airmass across the Northern Gulf from a modified arctic airmass that has been in place across the Mid South through the latter part of this week and is best identified by a rather tight dewpoint gradient across North Florida and Southern Georgia. An area of lower level clouds persist along this frontal zone and this will help keep temperatures warmer along and south of the front. The cloud cover is also expected to limit fog potential overnight as well. As much like the last few nights, quiet weather is expected with temperatures in the mid to upper 50s in North Florida with cooler values in the mid to upper 40s across South Central Georgia. && .SHORT TERM [Sunday Through Monday]... The weakening cold front, which will be pushing southward through the region tonight, will all but dissipate across the region on Sunday with just some lingering cloudiness in its wake. With upper level ridging quickly building in from the southeast, temperatures will continue to be quite warm and average several degrees above climatology. High temps on Sunday will range from the upper 60s to the middle 70s, and from the lower 70s to near 80 in some spots on Monday. Low temps will range from the mid to upper 40s over the interior on Sunday Night (with lower 50s near the coast), and moderate to the lower to mid 50s on Monday Night (with some upper 50s near the coast). Furthermore, despite some lingering moisture along the front and its remnants, the chances for any measurable rainfall through the period will be very slim at best. && .LONG TERM [Monday Night through Saturday]... The period will begin with strong Upper Level Ridging over the SE U.S., with 500 mb heights likely between 584 and 586 dm across the CWA on Tuesday. With quite warm 850 mb temps and a Sfc Ridge well to our east, High temps at the Sfc could reach the Upper 70s to the Lower 80s. Wed. should be unseasonably warm as well, with the actual Max temps dependent on how quickly the next Cold Front approaches the region from the NW. The Global Models are now also in fairly good agreement with the timing of this front, with slight differences accounting for a either Wed. Night or Thu. Morning passage. Another important change to this current fcst will be the increasing possibility for some strong to potentially severe thunderstorms developing in advance of this Front, as the models have become more energetic with this system and are carving out a steeper Upper Level Trof. If the low level instability is sufficient, the strong dynamics and kinematics could make this a potentially interesting event, and it will be monitored closely over the next several days. After the Cold Front pushes through, there is now good model consensus that much cooler and drier air will dominate the remainder of the period. && .AVIATION [Through 00Z Monday]... A weak cold front will drift slowly southward overnight and early Sunday, with weak dry air advection developing in the boundary layer as winds become N. The consensus of the latest high resolution models is that any fog that forms will be south of KTLH and KECP, though the 19 UTC HRRR run forecasts dense fog at KECP late. We are following the model/MOS consensus and calling for VFR conditions through the period, with light NW-N winds tonight, becoming E-SE 5 to 8 KT Sunday afternoon. && .MARINE... Winds will remain light and seas will remain low through the remainder of the weekend as a weakening cold front dissipates over the marine area. Thereafter, winds and seas will begin to increase out of the southeast early in the week, with cautionary to advisory level conditions now expected out of the South and Southwest ahead of the next cold front during the middle of the week. && .FIRE WEATHER... A weak cold front to our north will push through overnight, bringing with it slightly drier air. In FL however, relative humidities will not dip to 35 expect maybe in Jackson county. By Monday, relative humidities will increase again. The next drop in humidity will be mid to late next week behind the next cold front. && .HYDROLOGY... No rises are expected on area rivers over the next few days, with the next chance for widespread measurable rainfall not until next Wednesday into Thursday. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 55 75 49 76 53 / 0 0 10 10 10 Panama City 57 71 55 72 59 / 0 0 10 10 10 Dothan 51 71 49 73 53 / 0 0 10 10 10 Albany 45 69 45 74 52 / 0 0 10 10 10 Valdosta 53 71 49 77 53 / 0 0 10 10 10 Cross City 54 76 51 78 52 / 0 0 10 10 10 Apalachicola 58 69 55 69 59 / 0 0 10 10 10 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Godsey SHORT TERM...Gould LONG TERM...Gould AVIATION...Fournier MARINE...Gould FIRE WEATHER...Moore HYDROLOGY...Gould
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
639 AM EST FRI JAN 25 2013 .SYNOPSIS... HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY. A COLD FRONT WILL DROP THROUGH LATE FRIDAY NIGHT. HIGH PRESSURE WILL BUILD IN SATURDAY THROUGH EARLY NEXT WEEK. A WARMING TREND IS EXPECTED NEXT WEEK BEFORE ANOTHER COLD FRONT SWEEPS THROUGH THE SOUTHEAST WEDNESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ONLY CHANGE FOR THE SUNRISE UPDATE WAS TO INCREASE HIGHS 1-2 DEGREES ACROSS THE EASTERN HALF OF THE FORECAST AREA. HIGH RESOLUTION MODELS ARE INSISTENT THAT THE WEDGE WILL ERODE INTO THE SOUTHERN MIDLANDS AND CSRA LATER THIS AFTERNOON ALLOWING TEMPERATURES TO RISE INTO THE UPPER 50S TO NEAR 60 WELL INLAND. WILL LET THE DAY CREW MAKE THE DECISION TO MAKE ANY ADDITIONAL CHANGES AFTER THE 12Z MODEL DATA ARRIVE AND ARE EVALUATED. OVERVIEW: THE COLD FRONT WHICH PASSED THROUGH YESTERDAY AFTERNOON IS LOCATED WELL TO THE SOUTH WITH MODIFIED ARCTIC AIR OOZING INTO THE REGION. THE ARCTIC AIRMASS IS BEING MODIFIED SIGNIFICANTLY IN THE SAVANNAH-DARIEN-LUDOWICI CORRIDOR WHERE DEWPOINTS REMAIN IN THE LOWER 30S TO LOWER 40S WITH SURFACE TEMPERATURES STILL IN THE 40S AS OF 25/08Z...COURTESY OF MARINE INFLUENCES VIA NORTHEAST WINDS. EARLY MORNING SURFACE ANALYSIS SHOWS A WELL DEFINED INSITU WEDGE IS IN PLACE ACROSS NORTH CAROLINA...SOUTH CAROLINA AND GEORGIA WITH THE CORE OF THE WEDGE HIGH CENTERED OVER THE MID-ATLANTIC STATES. THE WEDGE WILL EXTEND ACROSS THE CAROLINA PIEDMONT TODAY AS THE REGION REMAINS CAUGHT IN A STIFF NORTHWEST FLOW REGIME ALOFT. THE FORECAST CONCERNS TODAY CENTER AROUND PINNING DOWN HIGH TEMPERATURES AND RAIN CHANCES. RAIN CHANCES: THE 25/00Z MODELS ARE FINALLY CONVERGING ON A MORE UNIFIED SOLUTION FOR RAIN CHANCES TODAY. ALL AGREE THAT THE BETTER PROBABILITIES FOR MEASURABLE RAINFALL WILL BE DISPLACED WELL TO THE NORTH AND WEST OF THE LOCAL FORECAST AREA COINCIDENT WITH THE STRONGEST ISENTROPIC ASSENT ATOP THE INLAND WEDGE. THE AIRMASS OVER THE WEDGE WILL SIMPLY REMAIN TOO DRY TO SUPPORT MEASURABLE RAINFALL THIS FAR SOUTH UNTIL POSSIBLY VERY LATE IN THE AFTERNOON WELL INLAND. THE MOST RECENT RUNS OF THE HIGHER RESOLUTION NSSL WRF...H3R AND RAP ALSO AGREE WITH THIS SCENARIO SO WILL LOWER POPS ACROSS THE BOARD...KEEPING A SLIGHT CHANCE FOR SHOWERS THIS AFTERNOON FOR THE COUNTIES BORDERING THE CSRA...SOUTHERN MIDLANDS AND THE NORTHERN SOUTH CAROLINA COAST TO BETTER BLEND WITH THE COLLABORATED HIGHER POP FORECASTS FROM THE COLUMBIA AND WILMINGTON WEATHER FORECAST OFFICES. TEMPERATURES: IT WILL BE ANOTHER EXTREMELY CHALLENGING HIGH TEMPERATURE FORECAST TODAY. MOST OF THE MODELS SHOW THE WEDGE HOLDING FIRM FOR MUCH OF THE MORNING...BUT GRADUALLY BREAK IT DOWN DURING THE AFTERNOON AS THE WEDGE HIGH SLOWLY SHIFTS OFF THE NORTH CAROLINA/VIRGINA COAST. ALTHOUGH PRECIPITATION FALLING OVER THE CENTRAL/NORTHERN MIDLANDS...THE PEE DEE AND NORTH CAROLINA WILL LIKELY HOLD A PIECE OF THE WEDGE IN PLACE AS STRONG DIABATIC PROCESSES TAKE HOLD...THE LACK OF A STRONG CONFLUENT FLOW OVER THE MID-ATLANTIC SUGGESTS THE WEDGE HIGH WILL NOT BE LOCKED IN AS IS TYPICAL IN MORE CLASSIC COLD AIR DAMMING EVENTS...HENCE THIS WEDGE IS MORE INSITU IN NATURE. WOULD NORMALLY UTILIZE THE COLDER SIDE OF THE GUIDANCE ENVELOP ACROSS INLAND AREAS GIVEN THE USUAL MODEL BIASES OF BREAKING WEDGES DOWN TOO QUICKLY...BUT SINCE LITTLE IF ANY PRECIPITATION WILL FALL ACROSS THE AREA OR THE SOUTHERN MIDLANDS TODAY...THE QUICKER EROSION OF THE WEDGE SEEMS QUITE PLAUSIBLE. HOWEVER...THE EXACT TIMING IS STILL UNKNOWN WHICH WILL HAVE A MAJOR IMPACT ON HOW MUCH WARMING WILL OCCUR ACROSS FAR INLAND AREAS. WILL ONLY NUDGE HIGHS UP A FEW DEGREES INTO THE UPPER 40S/LOWER 50S ACROSS FAR INLAND AREAS PER COORDINATION WITH THE PEACHTREE CITY...WILMINGTON AND COLUMBIA OFFICES...HOWEVER WARMER TEMPERATURES WILL BE POSSIBLE IF THE WEDGE ERODES QUICKER THAN WHAT IS EXPECTED. THERE WILL BE A LARGE THERMAL GRADIENT ACROSS SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA TODAY WITH HIGHS RANGING FROM THE UPPER 40S/LOWER 50S WELL INLAND TO THE MID 60S ACROSS PARTS OF LIBERTY...LONG AND MCINTOSH COUNTIES. MODELS SHOW SKIES BREAKING ACROSS THE FAR SOUTH AS THE WEDGE FRONT ERODES INLAND AND THERE IS A POTENTIAL FOR TEMPERATURES TO WARM EVEN MORE. GIVEN ALL OF THE UNKNOWNS TODAY...FURTHER REFINEMENTS TO THE TEMPERATURE FORECAST WILL MOST CERTAINLY BE NEEDED AS THE DAY PROGRESSES. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TONIGHT...COLD AIR DAMMING WILL BREAK DOWN QUICKLY THIS EVENING AS THE WEDGE HIGH SHIFTS OFFSHORE AND A COLD FRONT APPROACHES FROM THE NORTHWEST. IT LOOKS AS THOUGH THE FRONT WILL BE QUITE A BIT SLOWER TO PASS THROUGH THE REGION TONIGHT...LIKELY NOT PUSHING OFFSHORE UNTIL SATURDAY. UPPER LEVEL SUPPORT LOOKS MEAGER FOR MEASURABLE RAINFALL TO OCCUR WITH THE FRONT...BUT SEVERAL MODELS DO SPIT OUT A FEW HUNDREDTHS OF RAIN OVER SOME AREAS OVERNIGHT. FORECAST SOUNDINGS SUGGEST THE ATMOSPHERE WILL BE MOIST ENOUGH TO SUPPORT AT LEAST ISOLATED SHOWERS...SO WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS...MAINLY ACROSS THE WESTERN AND NORTHERN AREAS TONIGHT. LOWS WILL RANGE FROM THE LOWER 40S INLAND TO THE LOWER- MID 50S ALONG THE COAST. SATURDAY...THE COLD FRONT WILL CONTINUE TO DROP THROUGH THE FORECAST AREA SATURDAY MORNING...PROGRESSING STEADILY SOUTH OF THE REGION BY THE AFTERNOON HOURS. FORECAST SOUNDINGS SUGGEST ANY LOW TO MID LEVEL MOISTURE WILL QUICKLY DISSIPATE BY MID MORNING...THUS ANY POTENTIAL FOR PRECIPITATION WITH THE DESCENDING FRONT REMAINS QUITE LOW. HAVE THUS MAINTAINED POPS BELOW 15 PERCENT. A DECENT HIGH TEMPERATURE GRADIENT COULD SET UP SATURDAY AFTERNOON...AS THE NORTHERN AREAS QUICKLY FALL WITHIN COOLER NORTHERLY FLOW BEHIND THE FRONT...WHILE SOUTHERN SECTIONS REMAIN UNDER A MORE MILD WEST FLOW. BOTH NAM AND GFS MODEL GUIDANCE HAVE TRENDED WARMER WITH TEMPERATURES FOR SATURDAY...AND HAVE THUS INDICATED HIGHS RANGING FROM THE LOW 60S CHARLESTON TRI COUNTY AREA TO NEAR 70 DEGREES ALONG THE ALTAMAHA RIVER IN FAR SOUTHEAST GEORGIA. LOW TEMPERATURES SATURDAY NIGHT WILL BE NOTABLY COOLER HOWEVER...AS HIGH PRESSURE BUILDING FROM THE NORTH ADVECTS A COLDER AIR MASS ACROSS THE ENTIRE FORECAST AREA OVERNIGHT. LOW TEMPERATURES WILL FALL INTO THE LOWER 30S NORTH/NORTHWEST TO THE UPPER 30S SOUTHEAST GEORGIA. SUNDAY...A HIGH PRESSURE WEDGE WILL BE ESTABLISHED ACROSS THE MID ATLANTIC AND SOUTHEAST STATES. THIS PATTERN WILL CREATE ANOTHER DECENT NORTHWEST TO SOUTHEAST TEMPERATURE GRADIENT...WITH COOLER THAN NORMAL HIGHS IN THE MID 50S NORTHERN SOUTH CAROLINA COUNTIES AND MORE SEASONAL TEMPERATURES IN THE LOWER 60S SOUTH OF THE SAVANNAH RIVER. SOME MID TO HIGH LEVEL CLOUDS MOVING INTO THE AREA FROM THE WEST WILL HELP MODERATE LOW TEMPERATURES SUNDAY NIGHT IN THE UPPER 30S FAR INLAND TO THE LOWER 40S CLOSER TO THE COAST. RIDGING AT THE SURFACE AND ALOFT...ALONG WITH LIMITED DEEP MOISTURE...SUGGESTS DRY CONDITIONS FOR SUNDAY. MONDAY...AS THE CENTER OF SURFACE HIGH PRESSURE SLIPS OFF THE EAST COAST...A WELL-DEFINED COASTAL TROUGH WILL LIKELY DEVELOP OVER THE SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA NEARSHORE WATERS. WINDS WILL STEADILY VEER SOUTHEAST TO SOUTH AS THE DAY PROGRESSES...AND EXPECT WARMER HIGH TEMPERATURES IN THE 60 DEGREE RANGE AS A RESULT. WEAK CONVERGENCE ASSOCIATED WITH THE COASTAL TROUGH COULD PRODUCE ISOLATED SHOWERS JUST OFF THE COASTLINE...HOWEVER CONFIDENCE IN COVERAGE IS TOO LOW TO RAISE POPS ABOVE ABOUT 12 PERCENT AT THIS TIME. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... SURFACE HIGH PRESSURE WILL SETTLE OVER THE NEARBY ATLANTIC WATERS MONDAY NIGHT THROUGH EARLY WEDNESDAY...BEFORE A DEEP UPPER TROUGH SWEEPS TOWARD THE AREA FROM THE NORTHERN GREAT PLAINS AND SHIFTS A COLD FRONT INTO THE EAST COAST STATES. EXPECT A DECENT WARMING TREND FOR TUESDAY AND WEDNESDAY...AS THE REGION REMAINS WITHIN WARM SOUTHERLY FLOW DOWNSTREAM OF THE APPROACHING COLD FRONT. TEMPERATURES WILL PEAK IN THE LOW TO MID 70S AWAY FROM THE IMMEDIATE COASTLINE EACH AFTERNOON. RAIN CHANCES WILL THEN INCREASE FROM WEST TO EAST EARLY WEDNESDAY AS THE FRONT PUSHES INTO THE FORECAST AREA...AND HAVE INDICATED POPS IN THE 30 PERCENT RANGE BY WEDNESDAY NIGHT WITH THE FRONT AND DEEPEST MOISTURE DIRECTLY OVER THE SOUTHEAST STATES. NUMERICAL MODEL GUIDANCE DIVERGES QUITE A BIT REGARDING THE PATTERN EVOLUTION AFTER THE FRONT PUSHES OFFSHORE ON THURSDAY. AT THIS POINT...HAVE GENERALLY LEANED TOWARD PERSISTENCE WITH A CLEANER FRONTAL PASSAGE AND COOLER TEMPERATURES THURSDAY AND FRIDAY. HOWEVER...HAVE MAINTAINED JUST SLIGHT RAIN CHANCES THROUGH FRIDAY TO ACCOUNT FOR MODEL DISCREPANCIES LATE IN THE PERIOD. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/... LOW CLOUDS HAVE BEEN IN AND OUT AT KSAV AND HAVE REMAINED JUST SOUTH OF KCHS OVER THE PAST FEW HOURS. SATELLITE SHOWS AN EXPANDING AREA OF CIGS 1500-2500 FT JUST WEST OF KSAV AND SHOULD MOVE INTO THAT TERMINAL SHORTLY AND REMAIN THROUGH ABOUT 17Z BEFORE BREAKING TO VFR AS THE WEDGE ERODES INLAND. AT KCHS...MVFR CIGS WILL BE A BIT SLOWER TO ARRIVE...LIKELY 15-16Z AND REMAIN THROUGH EARLY AFTERNOON BEFORE LIFTING TO VFR. VFR IS ANTICIPATED FOR THE REMAINDER OF THE 12Z TAF PERIOD. EXTENDED AVIATION OUTLOOK...THERE IS A LOW CHANCE OF MVFR CIGS/VSBYS FRIDAY NIGHT INTO EARLY SATURDAY WITH A PASSING COLD FRONT. && .MARINE... TODAY...WINDS WILL GRADUALLY SUBSIDE OVER THE LOCAL MARINE AREA TODAY. WINDS ARE FORECAST TO GRADUALLY VEER MORE ONSHORE AND EVENTUALLY TO THE SOUTH AS THE INLAND WEDGE ERODES. WINDS MAY ACTUALLY GO VARIABLE FOR A FEW HOURS ACROSS THE GEORGIA WATERS THIS AFTERNOON AS BOTH THE NAM/RAP SHOW WEAK LOW PRESSURE OR WAVE FORMING ALONG A SUBTLE COASTAL THROUGH OFFSHORE OF THE GEORGIA COAST. SEAS WILL SUBSIDE TO 2-4 FT NEARSHORE WATERS AND 3-5 FT OFFSHORE WATERS BY AFTERNOON. TONIGHT...WINDS WILL VEER SOUTHWEST AHEAD OF A SLOW MOVING COLD FRONT TONIGHT. LOW-LEVEL JETTING AHEAD OF THE FRONT LOOKS MEAGER AT BEST...BUT MAY BE ENOUGH TO RAISE WINDS BACK TO 15-20 KT FOR MOST LEGS. SEAS WILL RESPOND SLIGHTLY...BUT BOTH WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS. SATURDAY THROUGH TUESDAY...SURFACE FLOW WILL STEADILY VEER TO THE NORTH AND BRIEFLY DIMINISH BEHIND A DESCENDING COLD FRONT SATURDAY. SURFACE HIGH PRESSURE BUILDING FROM THE NORTH BEHIND THE FRONT WILL THEN SUPPORT A BRIEF SURGE IN NORTHERLY FLOW ON SUNDAY THAT COULD APPROACH MARGINAL SMALL CRAFT ADVISORY THRESHOLDS. THE CENTER OF THE SURFACE HIGH WILL THEN SHIFT OFF THE COAST AND INTO THE MARINE ZONES MONDAY AND TUESDAY...ALLOWING MODERATE SOUTHERLY FLOW TO PREVAIL. CONDITIONS APPEARS TO REMAIN BELOW ADVISORY LEVELS MONDAY AND TUESDAY. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR AMZ352- 354. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ374. && $$ ST/79
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
406 AM EST FRI JAN 25 2013 .SYNOPSIS... HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY. A COLD FRONT WILL DROP THROUGH LATE FRIDAY NIGHT. HIGH PRESSURE WILL BUILD IN SATURDAY THROUGH EARLY NEXT WEEK. A WARMING TREND IS EXPECTED NEXT WEEK BEFORE ANOTHER COLD FRONT SWEEPS THROUGH THE SOUTHEAST WEDNESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... OVERVIEW: THE COLD FRONT WHICH PASSED THROUGH YESTERDAY AFTERNOON IS LOCATED WELL TO THE SOUTH WITH MODIFIED ARCTIC AIR OOZING INTO THE REGION. THE ARCTIC AIRMASS IS BEING MODIFIED SIGNIFICANTLY IN THE SAVANNAH-DARIEN-LUDOWICI CORRIDOR WHERE DEWPOINTS REMAIN IN THE LOWER 30S TO LOWER 40S WITH SURFACE TEMPERATURES STILL IN THE 40S AS OF 25/08Z...COURTESY OF MARINE INFLUENCES VIA NORTHEAST WINDS. EARLY MORNING SURFACE ANALYSIS SHOWS A WELL DEFINED INSITU WEDGE IS IN PLACE ACROSS NORTH CAROLINA...SOUTH CAROLINA AND GEORGIA WITH THE CORE OF THE WEDGE HIGH CENTERED OVER THE MID-ATLANTIC STATES. THE WEDGE WILL EXTEND ACROSS THE CAROLINA PIEDMONT TODAY AS THE REGION REMAINS CAUGHT IN A STIFF NORTHWEST FLOW REGIME ALOFT. THE FORECAST CONCERNS TODAY CENTER AROUND PINNING DOWN HIGH TEMPERATURES AND RAIN CHANCES. RAIN CHANCES: THE 25/00Z MODELS ARE FINALLY CONVERGING ON A MORE UNIFIED SOLUTION FOR RAIN CHANCES TODAY. ALL AGREE THAT THE BETTER PROBABILITIES FOR MEASURABLE RAINFALL WILL BE DISPLACED WELL TO THE NORTH AND WEST OF THE LOCAL FORECAST AREA COINCIDENT WITH THE STRONGEST ISENTROPIC ASSENT ATOP THE INLAND WEDGE. THE AIRMASS OVER THE WEDGE WILL SIMPLY REMAIN TOO DRY TO SUPPORT MEASURABLE RAINFALL THIS FAR SOUTH UNTIL POSSIBLY VERY LATE IN THE AFTERNOON WELL INLAND. THE MOST RECENT RUNS OF THE HIGHER RESOLUTION NSSL WRF...H3R AND RAP ALSO AGREE WITH THIS SCENARIO SO WILL LOWER POPS ACROSS THE BOARD...KEEPING A SLIGHT CHANCE FOR SHOWERS THIS AFTERNOON FOR THE COUNTIES BORDERING THE CSRA...SOUTHERN MIDLANDS AND THE NORTHERN SOUTH CAROLINA COAST TO BETTER BLEND WITH THE COLLABORATED HIGHER POP FORECASTS FROM THE COLUMBIA AND WILMINGTON WEATHER FORECAST OFFICES. TEMPERATURES: IT WILL BE ANOTHER EXTREMELY CHALLENGING HIGH TEMPERATURE FORECAST TODAY. MOST OF THE MODELS SHOW THE WEDGE HOLDING FIRM FOR MUCH OF THE MORNING...BUT GRADUALLY BREAK IT DOWN DURING THE AFTERNOON AS THE WEDGE HIGH SLOWLY SHIFTS OFF THE NORTH CAROLINA/VIRGINA COAST. ALTHOUGH PRECIPITATION FALLING OVER THE CENTRAL/NORTHERN MIDLANDS...THE PEE DEE AND NORTH CAROLINA WILL LIKELY HOLD A PIECE OF THE WEDGE IN PLACE AS STRONG DIABATIC PROCESSES TAKE HOLD...THE LACK OF A STRONG CONFLUENT FLOW OVER THE MID-ATLANTIC SUGGESTS THE WEDGE HIGH WILL NOT BE LOCKED IN AS IS TYPICAL IN MORE CLASSIC COLD AIR DAMMING EVENTS...HENCE THIS WEDGE IS MORE INSITU IN NATURE. WOULD NORMALLY UTILIZE THE COLDER SIDE OF THE GUIDANCE ENVELOP ACROSS INLAND AREAS GIVEN THE USUAL MODEL BIASES OF BREAKING WEDGES DOWN TOO QUICKLY...BUT SINCE LITTLE IF ANY PRECIPITATION WILL FALL ACROSS THE AREA OR THE SOUTHERN MIDLANDS TODAY...THE QUICKER EROSION OF THE WEDGE SEEMS QUITE PLAUSIBLE. HOWEVER...THE EXACT TIMING IS STILL UNKNOWN WHICH WILL HAVE A MAJOR IMPACT ON HOW MUCH WARMING WILL OCCUR ACROSS FAR INLAND AREAS. WILL ONLY NUDGE HIGHS UP A FEW DEGREES INTO THE UPPER 40S/LOWER 50S ACROSS FAR INLAND AREAS PER COORDINATION WITH THE PEACHTREE CITY...WILMINGTON AND COLUMBIA OFFICES...HOWEVER WARMER TEMPERATURES WILL BE POSSIBLE IF THE WEDGE ERODES QUICKER THAN WHAT IS EXPECTED. THERE WILL BE A LARGE THERMAL GRADIENT ACROSS SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA TODAY WITH HIGHS RANGING FROM THE UPPER 40S/LOWER 50S WELL INLAND TO THE MID 60S ACROSS PARTS OF LIBERTY...LONG AND MCINTOSH COUNTIES. MODELS SHOW SKIES BREAKING ACROSS THE FAR SOUTH AS THE WEDGE FRONT ERODES INLAND AND THERE IS A POTENTIAL FOR TEMPERATURES TO WARM EVEN MORE. GIVEN ALL OF THE UNKNOWNS TODAY...FURTHER REFINEMENTS TO THE TEMPERATURE FORECAST WILL MOST CERTAINLY BE NEEDED AS THE DAY PROGRESSES. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TONIGHT...COLD AIR DAMMING WILL BREAK DOWN QUICKLY THIS EVENING AS THE WEDGE HIGH SHIFTS OFFSHORE AND A COLD FRONT APPROACHES FROM THE NORTHWEST. IT LOOKS AS THOUGH THE FRONT WILL BE QUITE A BIT SLOWER TO PASS THROUGH THE REGION TONIGHT...LIKELY NOT PUSHING OFFSHORE UNTIL SATURDAY. UPPER LEVEL SUPPORT LOOKS MEAGER FOR MEASURABLE RAINFALL TO OCCUR WITH THE FRONT...BUT SEVERAL MODELS DO SPIT OUT A FEW HUNDREDTHS OF RAIN OVER SOME AREAS OVERNIGHT. FORECAST SOUNDINGS SUGGEST THE ATMOSPHERE WILL BE MOIST ENOUGH TO SUPPORT AT LEAST ISOLATED SHOWERS...SO WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS...MAINLY ACROSS THE WESTERN AND NORTHERN AREAS TONIGHT. LOWS WILL RANGE FROM THE LOWER 40S INLAND TO THE LOWER- MID 50S ALONG THE COAST. SATURDAY...THE COLD FRONT WILL CONTINUE TO DROP THROUGH THE FORECAST AREA SATURDAY MORNING...PROGRESSING STEADILY SOUTH OF THE REGION BY THE AFTERNOON HOURS. FORECAST SOUNDINGS SUGGEST ANY LOW TO MID LEVEL MOISTURE WILL QUICKLY DISSIPATE BY MID MORNING...THUS ANY POTENTIAL FOR PRECIPITATION WITH THE DESCENDING FRONT REMAINS QUITE LOW. HAVE THUS MAINTAINED POPS BELOW 15 PERCENT. A DECENT HIGH TEMPERATURE GRADIENT COULD SET UP SATURDAY AFTERNOON...AS THE NORTHERN AREAS QUICKLY FALL WITHIN COOLER NORTHERLY FLOW BEHIND THE FRONT...WHILE SOUTHERN SECTIONS REMAIN UNDER A MORE MILD WEST FLOW. BOTH NAM AND GFS MODEL GUIDANCE HAVE TRENDED WARMER WITH TEMPERATURES FOR SATURDAY...AND HAVE THUS INDICATED HIGHS RANGING FROM THE LOW 60S CHARLESTON TRI COUNTY AREA TO NEAR 70 DEGREES ALONG THE ALTAMAHA RIVER IN FAR SOUTHEAST GEORGIA. LOW TEMPERATURES SATURDAY NIGHT WILL BE NOTABLY COOLER HOWEVER...AS HIGH PRESSURE BUILDING FROM THE NORTH ADVECTS A COLDER AIR MASS ACROSS THE ENTIRE FORECAST AREA OVERNIGHT. LOW TEMPERATURES WILL FALL INTO THE LOWER 30S NORTH/NORTHWEST TO THE UPPER 30S SOUTHEAST GEORGIA. SUNDAY...A HIGH PRESSURE WEDGE WILL BE ESTABLISHED ACROSS THE MID ATLANTIC AND SOUTHEAST STATES. THIS PATTERN WILL CREATE ANOTHER DECENT NORTHWEST TO SOUTHEAST TEMPERATURE GRADIENT...WITH COOLER THAN NORMAL HIGHS IN THE MID 50S NORTHERN SOUTH CAROLINA COUNTIES AND MORE SEASONAL TEMPERATURES IN THE LOWER 60S SOUTH OF THE SAVANNAH RIVER. SOME MID TO HIGH LEVEL CLOUDS MOVING INTO THE AREA FROM THE WEST WILL HELP MODERATE LOW TEMPERATURES SUNDAY NIGHT IN THE UPPER 30S FAR INLAND TO THE LOWER 40S CLOSER TO THE COAST. RIDGING AT THE SURFACE AND ALOFT...ALONG WITH LIMITED DEEP MOISTURE...SUGGESTS DRY CONDITIONS FOR SUNDAY. MONDAY...AS THE CENTER OF SURFACE HIGH PRESSURE SLIPS OFF THE EAST COAST...A WELL-DEFINED COASTAL TROUGH WILL LIKELY DEVELOP OVER THE SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA NEARSHORE WATERS. WINDS WILL STEADILY VEER SOUTHEAST TO SOUTH AS THE DAY PROGRESSES...AND EXPECT WARMER HIGH TEMPERATURES IN THE 60 DEGREE RANGE AS A RESULT. WEAK CONVERGENCE ASSOCIATED WITH THE COASTAL TROUGH COULD PRODUCE ISOLATED SHOWERS JUST OFF THE COASTLINE...HOWEVER CONFIDENCE IN COVERAGE IS TOO LOW TO RAISE POPS ABOVE ABOUT 12 PERCENT AT THIS TIME. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... SURFACE HIGH PRESSURE WILL SETTLE OVER THE NEARBY ATLANTIC WATERS MONDAY NIGHT THROUGH EARLY WEDNESDAY...BEFORE A DEEP UPPER TROUGH SWEEPS TOWARD THE AREA FROM THE NORTHERN GREAT PLAINS AND SHIFTS A COLD FRONT INTO THE EAST COAST STATES. EXPECT A DECENT WARMING TREND FOR TUESDAY AND WEDNESDAY...AS THE REGION REMAINS WITHIN WARM SOUTHERLY FLOW DOWNSTREAM OF THE APPROACHING COLD FRONT. TEMPERATURES WILL PEAK IN THE LOW TO MID 70S AWAY FROM THE IMMEDIATE COASTLINE EACH AFTERNOON. RAIN CHANCES WILL THEN INCREASE FROM WEST TO EAST EARLY WEDNESDAY AS THE FRONT PUSHES INTO THE FORECAST AREA...AND HAVE INDICATED POPS IN THE 30 PERCENT RANGE BY WEDNESDAY NIGHT WITH THE FRONT AND DEEPEST MOISTURE DIRECTLY OVER THE SOUTHEAST STATES. NUMERICAL MODEL GUIDANCE DIVERGES QUITE A BIT REGARDING THE PATTERN EVOLUTION AFTER THE FRONT PUSHES OFFSHORE ON THURSDAY. AT THIS POINT...HAVE GENERALLY LEANED TOWARD PERSISTENCE WITH A CLEANER FRONTAL PASSAGE AND COOLER TEMPERATURES THURSDAY AND FRIDAY. HOWEVER...HAVE MAINTAINED JUST SLIGHT RAIN CHANCES THROUGH FRIDAY TO ACCOUNT FOR MODEL DISCREPANCIES LATE IN THE PERIOD. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... SATELLITE SHOWS LOW CLOUDS BEGINNING TO BLOSSOM ALONG THE COAST WITH COASTAL OBSERVATIONS SHOWING MVFR CIGS. EXPECT CIGS OF 2-2.5 KFT TO MOVE INTO THE TERMINALS SHORTLY AND PERSIST FOR MUCH OF THE MORNING HOURS...POSSIBLY DROPPING AS LOW AS 1.5 KFT. ATTM IT APPEARS CIGS WILL REMAIN ABOVE IFR THRESHOLDS. THE WEDGE IS EXPECTED TO BREAKDOWN LATER TODAY AS HIGH PRESSURE BEGINS TO SHIFT OFFSHORE. THE TIMING OF THE RETURN TO VFR IS STILL UNCERTAIN...BUT FAVOR 20Z AT KSAV AND 22Z AT KCHS. REFINEMENTS WILL BE NEEDED AS THE DAY PROGRESSES. NO PRECIPITATION IS EXPECTED THROUGH THE PERIOD. EXTENDED AVIATION OUTLOOK...THERE IS A LOW CHANCE OF MVFR CIGS/VSBYS FRIDAY NIGHT INTO EARLY SATURDAY WITH A PASSING COLD FRONT. && .MARINE... THROUGH SUNRISE...FRISKY NORTHEAST WINDS REMAIN ACROSS THE MARINE AREA THIS MORNING BEING SUPPORTED BY A TIGHT PRESSURE GRADIENT BETWEEN WEAK LOW PRESSURE EAST OF CAPE CANAVERAL AND THE HIGH PRESSURE WEDGE INLAND. WILL MAINTAIN THE SMALL CRAFT ADVISORY FOR ALL LEGS THROUGH 8 AM. TODAY...WINDS WILL GRADUALLY SUBSIDE OVER THE LOCAL MARINE AREA TODAY. WINDS ARE FORECAST TO GRADUALLY VEER MORE ONSHORE AND EVENTUALLY TO THE SOUTH AS THE INLAND WEDGE ERODES. WINDS MAY ACTUALLY GO VARIABLE FOR A FEW HOURS ACROSS THE GEORGIA WATERS THIS AFTERNOON AS BOTH THE NAM/RAP SHOW WEAK LOW PRESSURE OR WAVE FORMING ALONG A SUBTLE COASTAL THROUGH OFFSHORE OF THE GEORGIA COAST. SEAS WILL SUBSIDE TO 2-4 FT NEARSHORE WATERS AND 3-5 FT OFFSHORE WATERS BY AFTERNOON. TONIGHT...WINDS WILL VEER SOUTHWEST AHEAD OF A SLOW MOVING COLD FRONT TONIGHT. LOW-LEVEL JETTING AHEAD OF THE FRONT LOOKS MEAGER AT BEST...BUT MAY BE ENOUGH TO RAISE WINDS BACK TO 15-20 KT FOR MOST LEGS. SEAS WILL RESPOND SLIGHTLY...BUT BOTH WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS. SATURDAY THROUGH TUESDAY...SURFACE FLOW WILL STEADILY VEER TO THE NORTH AND BRIEFLY DIMINISH BEHIND A DESCENDING COLD FRONT SATURDAY. SURFACE HIGH PRESSURE BUILDING FROM THE NORTH BEHIND THE FRONT WILL THEN SUPPORT A BRIEF SURGE IN NORTHERLY FLOW ON SUNDAY THAT COULD APPROACH MARGINAL SMALL CRAFT ADVISORY THRESHOLDS. THE CENTER OF THE SURFACE HIGH WILL THEN SHIFT OFF THE COAST AND INTO THE MARINE ZONES MONDAY AND TUESDAY...ALLOWING MODERATE SOUTHERLY FLOW TO PREVAIL. CONDITIONS APPEARS TO REMAIN BELOW ADVISORY LEVELS MONDAY AND TUESDAY. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR AMZ330- 350-352-354. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ374. && $$ ST/79
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
549 AM CST FRI JAN 25 2013 .UPDATE... THE SNOW ACROSS THE AREA IS COMING TO A RAPID END. LOW LEVEL FORCING IN THE FORM OF SFC CONVERGENCE AIDED IN SATURATING THE LOW LEVELS TO PRODUCE -SN WHICH FOR THE MOST PART HAS RANGED FROM A TRACE TO A DUSTING. SAID LOW LEVEL SFC CONVERGENCE IS MOVING EAST OF THE MISSISSIPPI AND WILL EXIT THE CWFA IN THE NEXT 2-3 HRS. THE NEXT CONCERN IS CLOUD TRENDS. CLEARING FROM WEST TO EAST WILL OCCUR ACROSS THE CWFA STARTING AROUND SUNRISE AND MOST OF THE CWFA WILL BE CLEAR BY MID MORNING. THE QUESTION IS THE LOW CLOUDS IN THE DAKOTAS AND MINNESOTA. EXTRAPOLATION OFF SATELLITE AND INPUT FROM RECENT TRENDS WITH THE RAP MODEL SUGGEST THEY WILL ENTER THE CWFA BY LATE MORNING. HOWEVER...DAY TIME HEATING SHOULD ALLOW THE LEADING EDGE TO ERODE AS SOME MIXING OCCURS. SO...WILL SPEED UP THE CLEARING TREND DURING THE MORNING HOURS AND ADD JUST A BIT MORE CLOUDS FOR THE AFTERNOON. AND UPDATE REFLECTING THESE CHANGES WILL BE AVAILABLE SHORTLY. ..08.. && .AVIATION... THE -SN FOR THE MOST PART IS NOW OVER FOR ALL TAF SITES. SATELLITE TRENDS INDICATE CONDITIONS BECOMING VFR BY 15Z/25. SATELLITE AND RAP MODEL TRENDS SUGGEST THE LOW CLOUDS ACROSS THE DAKOTAS AND MINNESOTA WOULD IMPACT KCID/DBQ/KMLI AFT 18Z/25 WITH MVFR CONDITIONS. KCID/KMLI ARE MORE QUESTIONABLE AS THE LEADING EDGE OF THE CLOUDS SHOULD ERODE WITH DAY TIME HEATING. HOWEVER...KDBQ SHOULD SEE MVFR CONDITIONS DLVPG. VFR CONDITIONS ARE EXPECTED TO RE-DEVELOP AFT 00Z/26 AT ALL TAF SITES. ..08.. && .PREV DISCUSSION... /ISSUED 322 AM CST FRI JAN 25 2013/ SYNOPSIS... 06Z SFC ANALYSIS HAS A WARM FRONT RUNNING FROM THE EASTERN DAKOTAS INTO WEST TEXAS. A WEAK LOW WAS NEAR KJLN WITH AN INVERTED TROF RUNNING INTO SOUTHEAST NEBRASKA AND ANOTHER TROF RUNNING INTO CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS MUCH OF THE MIDWEST WITH 20S AND HIGHER IN THE SOUTHERN PLAINS AND DEEP SOUTH. SHORT TERM...TODAY AND TONIGHT... IMMEDIATE CONCERN IS THE SNOW POTENTIAL AND AMOUNTS. BASED ON DATA THROUGH 07Z...THE RAP TRENDS OF 850-700MB CONDENSATION PRESSURE DEFICITS BELOW 10...F VECTOR CONVERGENCE AND/OR 800-750MB CONVERGENCE...AND A THETA E GRADIENT SEEMS TO CORRELATE FAIRLY WELL WITH WHERE SNOW IS REACHING THE GROUND. USING THIS AS A ROUGH GUIDE THERE SHOULD BE A QUICK SHOT OF LIGHT SNOW MOVE THROUGH THE NORTHWEST QUADRANT OF THE CWFA IN THE 09-12Z TIME FRAME AND THEN THE NORTHEAST QUADRANT IN THE 12-15Z TIME FRAME. THE FCST SOUNDINGS FROM THE GFS LOOK OVERLY MOIST BUT THE WRF AND RAP DO HOLD ON TO A NARROW LAYER OF DRY AIR TO AROUND SUNRISE. THIS DRY AIR WILL HELP HOLD DOWN AMOUNTS. AS FOR AMOUNTS...A TRACE TO A DUSTING WILL BE ABOUT ALL THAT WILL OCCUR WITH THIS EVENT MAINLY FOR AREAS ALONG/NORTH OF I-80. THE OVERALL CONVERGENCE WEAKENS WITH TIME AS WELL SO THE SNOW SHOULD ONLY LAST FOR 2-3 HRS AT ANY GIVEN LOCATION. BASED ON SATELLITE TRENDS...THERE SHOULD BE A GENERAL CLEARING OF SKIES DURING THE LATE MORNING AND AFTERNOON HOURS. LOW LEVEL LAPSE RATES DO GET RELATIVELY STEEP ACROSS THE FAR NORTHEAST PARTS OF THE CWFA THAT MAY ALLOW SOME FLURRIES TO DEVELOP DURING THE AFTERNOON. TONIGHT...ANOTHER HIGH PRESSURE BUILDS INTO THE AREA RESULTING IN QUIET BUT DRY CONDITIONS. ..08.. LONG TERM...SATURDAY THROUGH NEXT THURSDAY... SATURDAY WILL BE RELATIVELY QUIET WITH WARM AIR ADVECTION GOING ON OVERHEAD FOR GRADUALLY WARMING TEMPERATURES. HIGHS SHOULD BE IN THE 20S TO NEARLY 30. SATURDAY NIGHT THROUGH MONDAY TO BE THE MAIN CONCERN OF THE SHIFT. THE UPPER LEVEL PATTERN HAS SHIFTED TO A BROAD RIDGE OVER THE MIDWEST BY SATURDAY NIGHT AND SUNDAY...WITH A SHARP UPPER LEVEL TROUGH MOVING ONTO THE WEST COAST. A SHORTWAVE EJECTS OUT OF A MORE SOUTHERN STREAM TROUGH...AND MOVES ACROSS THE MIDWEST THROUGH THE WEAKENING UPPER LEVEL RIDGE AXIS. THIS PRODUCES CYCLOGENESIS OVER NORTHEAST COLORADO ON SUNDAY. THE STRONG WARM AIR ADVECTION AHEAD OF THIS BRINGS 850MB TEMPERATURES OVER THE FORECAST AREA ABOVE FREEZING FOR MUCH OF SATURDAY NIGHT AND SUNDAY...JUST AS A NICE SLUG OF MOISTURE COMES INTO THE AREA FROM THE GULF...JUST AS THE SHORTWAVE MOVES ACROSS THE FORECAST AREA. THIS IS LIKELY TO PRODUCE A NICE WAVE OF WARM AIR ADVECTION OVER THE AREA STARTING LATE SATURDAY NIGHT AND CONTINUING THROUGH SUNDAY AND INTO MONDAY. HOWEVER...THE WARM AIR ADVECTION ALOFT IS GOING TO WARM ABOVE FREEZING BEFORE WE DO AT THE SURFACE. AN ISSUE OF LOW CONFIDENCE IN THIS FORECAST IS HOW COLD WE WILL BE ONCE THE PRECIPITATION MOVES INTO THE AREA...AND HOW QUICKLY TEMPERATURES WARM ON SUNDAY. THE NAM IS OF LITTLE HELP...AS IT HAS ALREADY INITIALIZED WITH 2-4 INCHES OF SNOW COVER ON THE GROUND OVER MUCH OF IOWA...WHICH DOES NOT EXIST. THIS IS GOING TO CONTAMINATE HOW QUICKLY IT WILL WARM TEMPERATURES ON SUNDAY. THE GFS SHOULD HAVE A SIMILAR INITIALIZATION. THE CANADIAN GEM IS BETTER. HOWEVER...NO MATTER THE SOLUTION IT APPEARS THAT WE ARE LOOKING AT AT LEAST A SHORT PERIOD OF FREEZING RAIN BEFORE TEMPERATURES WARM ABOVE FREEZING ON SUNDAY. IT IS A VERY TOUGH FORECAST...AND HOPEFULLY MODEL CHANGES BETWEEN NOW AND THEN WILL REMOVE THE SPECTER OF THE ICING FROM FREEZING RAIN. SUNDAY NIGHT AND MONDAY ALL THE PRECIPITATION GRADUALLY SHIFTS TO ALL RAIN AS TEMPERATURES CONTINUE TO WARM. THE SURFACE TROUGH AXIS GRADUALLY SHIFTS EAST OF THE AREA AND ALLOWS COLD AIR TO MOVE BACK INTO THE AREA BY TUESDAY...AND RAIN SHOULD CHANGE BACK TO SNOW BEFORE THIS EVENT ENDS TUESDAY AFTERNOON AND NIGHT. WEDNESDAY AND THURSDAY ANOTHER COLD FRONT MOVES THROUGH THE FORECAST AREA...AND BRINGS ANOTHER SHOT OF ARCTIC AIR INTO THE FORECAST AREA BY THURSDAY. HIGH TEMPERATURES SHOULD BE BACK INTO THE TEENS AND 20S BY THURSDAY. LE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
322 AM CST FRI JAN 25 2013 .SYNOPSIS... 06Z SFC ANALYSIS HAS A WARM FRONT RUNNING FROM THE EASTERN DAKOTAS INTO WEST TEXAS. A WEAK LOW WAS NEAR KJLN WITH AN INVERTED TROF RUNNING INTO SOUTHEAST NEBRASKA AND ANOTHER TROF RUNNING INTO CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS MUCH OF THE MIDWEST WITH 20S AND HIGHER IN THE SOUTHERN PLAINS AND DEEP SOUTH. && .SHORT TERM...TODAY AND TONIGHT... IMMEDIATE CONCERN IS THE SNOW POTENTIAL AND AMOUNTS. BASED ON DATA THROUGH 07Z...THE RAP TRENDS OF 850-700MB CONDENSATION PRESSURE DEFICITS BELOW 10...F VECTOR CONVERGENCE AND/OR 800-750MB CONVERGENCE...AND A THETA E GRADIENT SEEMS TO CORRELATE FAIRLY WELL WITH WHERE SNOW IS REACHING THE GROUND. USING THIS AS A ROUGH GUIDE THERE SHOULD BE A QUICK SHOT OF LIGHT SNOW MOVE THROUGH THE NORTHWEST QUADRANT OF THE CWFA IN THE 09-12Z TIME FRAME AND THEN THE NORTHEAST QUADRANT IN THE 12-15Z TIME FRAME. THE FCST SOUNDINGS FROM THE GFS LOOK OVERLY MOIST BUT THE WRF AND RAP DO HOLD ON TO A NARROW LAYER OF DRY AIR TO AROUND SUNRISE. THIS DRY AIR WILL HELP HOLD DOWN AMOUNTS. AS FOR AMOUNTS...A TRACE TO A DUSTING WILL BE ABOUT ALL THAT WILL OCCUR WITH THIS EVENT MAINLY FOR AREAS ALONG/NORTH OF I-80. THE OVERALL CONVERGENCE WEAKENS WITH TIME AS WELL SO THE SNOW SHOULD ONLY LAST FOR 2-3 HRS AT ANY GIVEN LOCATION. BASED ON SATELLITE TRENDS...THERE SHOULD BE A GENERAL CLEARING OF SKIES DURING THE LATE MORNING AND AFTERNOON HOURS. LOW LEVEL LAPSE RATES DO GET RELATIVELY STEEP ACROSS THE FAR NORTHEAST PARTS OF THE CWFA THAT MAY ALLOW SOME FLURRIES TO DEVELOP DURING THE AFTERNOON. TONIGHT...ANOTHER HIGH PRESSURE BUILDS INTO THE AREA RESULTING IN QUIET BUT DRY CONDITIONS. ..08.. .LONG TERM...SATURDAY THROUGH NEXT THURSDAY... SATURDAY WILL BE RELATIVELY QUIET WITH WARM AIR ADVECTION GOING ON OVERHEAD FOR GRADUALLY WARMING TEMPERATURES. HIGHS SHOULD BE IN THE 20S TO NEARLY 30. SATURDAY NIGHT THROUGH MONDAY TO BE THE MAIN CONCERN OF THE SHIFT. THE UPPER LEVEL PATTERN HAS SHIFTED TO A BROAD RIDGE OVER THE MIDWEST BY SATURDAY NIGHT AND SUNDAY...WITH A SHARP UPPER LEVEL TROUGH MOVING ONTO THE WEST COAST. A SHORTWAVE EJECTS OUT OF A MORE SOUTHERN STREAM TROUGH...AND MOVES ACROSS THE MIDWEST THROUGH THE WEAKENING UPPER LEVEL RIDGE AXIS. THIS PRODUCES CYCLOGENESIS OVER NORTHEAST COLORADO ON SUNDAY. THE STRONG WARM AIR ADVECTION AHEAD OF THIS BRINGS 850MB TEMPERATURES OVER THE FORECAST AREA ABOVE FREEZING FOR MUCH OF SATURDAY NIGHT AND SUNDAY...JUST AS A NICE SLUG OF MOISTURE COMES INTO THE AREA FROM THE GULF...JUST AS THE SHORTWAVE MOVES ACROSS THE FORECAST AREA. THIS IS LIKELY TO PRODUCE A NICE WAVE OF WARM AIR ADVECTION OVER THE AREA STARTING LATE SATURDAY NIGHT AND CONTINUING THROUGH SUNDAY AND INTO MONDAY. HOWEVER...THE WARM AIR ADVECTION ALOFT IS GOING TO WARM ABOVE FREEZING BEFORE WE DO AT THE SURFACE. AN ISSUE OF LOW CONFIDENCE IN THIS FORECAST IS HOW COLD WE WILL BE ONCE THE PRECIPITATION MOVES INTO THE AREA...AND HOW QUICKLY TEMPERATURES WARM ON SUNDAY. THE NAM IS OF LITTLE HELP...AS IT HAS ALREADY INITIALIZED WITH 2-4 INCHES OF SNOW COVER ON THE GROUND OVER MUCH OF IOWA...WHICH DOES NOT EXIST. THIS IS GOING TO CONTAMINATE HOW QUICKLY IT WILL WARM TEMPERATURES ON SUNDAY. THE GFS SHOULD HAVE A SIMILAR INITIALIZATION. THE CANADIAN GEM IS BETTER. HOWEVER...NO MATTER THE SOLUTION IT APPEARS THAT WE ARE LOOKING AT AT LEAST A SHORT PERIOD OF FREEZING RAIN BEFORE TEMPERATURES WARM ABOVE FREEZING ON SUNDAY. IT IS A VERY TOUGH FORECAST...AND HOPEFULLY MODEL CHANGES BETWEEN NOW AND THEN WILL REMOVE THE SPECTER OF THE ICING FROM FREEZING RAIN. SUNDAY NIGHT AND MONDAY ALL THE PRECIPITATION GRADUALLY SHIFTS TO ALL RAIN AS TEMPERATURES CONTINUE TO WARM. THE SURFACE TROUGH AXIS GRADUALLY SHIFTS EAST OF THE AREA AND ALLOWS COLD AIR TO MOVE BACK INTO THE AREA BY TUESDAY...AND RAIN SHOULD CHANGE BACK TO SNOW BEFORE THIS EVENT ENDS TUESDAY AFTERNOON AND NIGHT. WEDNESDAY AND THURSDAY ANOTHER COLD FRONT MOVES THROUGH THE FORECAST AREA...AND BRINGS ANOTHER SHOT OF ARCTIC AIR INTO THE FORECAST AREA BY THURSDAY. HIGH TEMPERATURES SHOULD BE BACK INTO THE TEENS AND 20S BY THURSDAY. LE && .AVIATION... VFR CONDITIONS CONTINUE ACROSS THE AREA WITH SOME POCKETS OF MVFR. HOWEVER...THE MODELS CONTINUE TO SHOW A TOP DOWN SATURATION OCCURRING WHICH WILL ALLOW MVFR CONDITIONS OR BORDERLINE MVFR CONDITIONS FROM 09Z/25 TO 15Z/25 DUE TO A PASSING STORM SYSTEM. THIS STORM SYSTEM SHOULD RESULT IN -SN OCCURRING BRIEFLY AT KCID/KDBQ/KMLI. ONCE THE STORM SYSTEM MOVES THROUGH CONDITIONS ARE EXPECTED TO IMPROVE TO VFR BY OR AFT 18Z/25. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ LE/08
AREA FORECAST DISCUSSION
NWS GOODLAND KS
755 PM MST SAT JAN 26 2013 .UPDATE... ISSUED AT 755 PM MST SAT JAN 26 2013 UPDATE SENT FOR TONIGHT-SUNDAY PERIOD. AT 03Z WARM FRONT AND LIGHT RAIN PUSHING INTO THE SOUTHWEST AND WESTERN PART OF THE FORECAST AREA. AS THE WARM FRONT LIFTS NORTH/NORTHEAST OVERNIGHT EXPECT SOME RAIN ALONG AND NORTH OF IT WHILE TO THE SOUTH DECREASING CLOUDINESS EXPECTED. EXCEPTION WILL BE ACROSS THE EASTERN 1/3-1/4 OF THE AREA WHERE SOUTHERLY COMPONENT TO THE WIND WILL MAINTAIN HIGH BOUNDARY LAYER MOISTURE AND A THREAT FOR FOG. AS THE SYSTEM CONTINUES TO LIFT EAST/NORTHEAST ON SUNDAY NORTHWEST WINDS WILL DEVELOP ON THE BACKSIDE PUSHING THE LOW CLOUDS AND FOG OUT OF THE AREA BY MID TO LATE MORNING. ELSEWHERE MAY SEE SOME WRAPAROUND CLOUDINESS EARLY WITH NO PRECIPITATION EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 135 PM MST SAT JAN 26 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW SHORTWAVE RIDGING ACROSS THE SOUTHERN PLAINS WITH A SERIES OF SHORTWAVE TROUGHS OVER SOUTHERN CALIFORNIA AND OFF THE PACIFIC NW COAST. THE FIRST OF THESE TROUGHS OVER SOUTHERN CALIFORNIA WILL BE THE MAIN WEATHER PRODUCER FOR US TONIGHT WITH MID-HIGH CLOUDS ALREADY INCREASING AHEAD OF THIS FEATURE OVER COLORADO AND WESTERN KS. GUIDANCE IN GENERAL AGREEMENT ON PRECIP SPREADING FROM THE WEST TO THE EAST THROUGH THE EVENING HOURS...WITH BEST COVERAGE/CHANCES ACROSS THE EAST/NORTHEAST AFTER MIDNIGHT AS A WARM FRONT MOVES NORTH AND MOISTURE ADVECTION INCREASES. IM NOT AS CONFIDENT ABOUT COVERAGE DURING THE EVENING WITH MOISTURE ADVECTION BELOW H7 MARGINAL UNTIL 06Z. NAM IS ADVERTISING DRY SLOT QUICKLY MOVING FROM THE W/SW LATE THIS EVENING THROUGH SUNDAY MORNING...AND WITH STRONG DRY SLOT ALREADY APPARENT ON WV IMAGERY THIS MAY BE REASONABLE. I HAVE TRENDED POPS HIGHER ACROSS THE NORTHEAST AROUND 06-12Z...AND HAVE DECREASED POPS QUICKER ACROSS THE SW DURING THIS SAME TIME PERIOD. OVERALL QPF AMOUNTS SHOULD BE LIGHT...WITH HIGHEST TOTALS IN SW NEBRASKA AND NORTH CENTRAL KS WHERE UP TO 0.10 INCHES OF LIQUID IS POSSIBLE. AS WITH PREVIOUS FORECASTS I KEPT PRECIP TYPE ALL RAIN WITH MODEL SOUNDINGS SUPPORTING ALL LIQUID...AND SURFACE TEMPERATURES EXPECTED TO REMAIN ABOVE FREEZING WHERE PRECIP/CLOUD COVER IS LINGERING AFTER MIDNIGHT. BELOW FREEZING TEMPS WILL BE POSSIBLE IN THE W/SW WHERE SKIES WILL BE CLEARING...HOWEVER PRECIP WILL BE OVER WITH AT THAT POINT. WITH INCREASING LOW LEVEL MOISTURE ACROSS THE NORTH AND EAST WE COULD ALSO SEE PATCHY FOG DEVELOPMENT LATE TONIGHT INTO SUNDAY MORNING BEFORE THE WARM FROM FINAL PUSHES NORTH INTO CENTRAL NEBRASKA BEFORE 18Z...WITH DRY/STABLE CONDITIONS EXPECTED THROUGH THE REST OF SUNDAY. WITH CLEARING SKIES...AND 10-14C H85 TEMPS ADVECTING OVER THE CWA FROM THE WEST WE SHOULD SEE ANOTHER MILD DAY WITH TEMPERATURES IN THE MIDDLE 60S IN THE SOUTH TO THE LOW 50S NEAR MCCOOK WHERE CLOUD COVER MAY LINGER LONGER INTO THE AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 135 PM MST SAT JAN 26 2013 MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH MONDAY. SYSTEM WILL MOVE THROUGH MONDAY NIGHT BRINGING A CHANCE OF LIGHT SNOW AND COLDER TEMPERATURES. THERE COULD BE A BRIEF PERIOD OF LIGHT RAIN AHEAD OF THE FRONT...BUT IT WILL QUICKLY CHANGE TO SNOW. LIGHT SNOW OR FLURRIES COULD LINGER INTO TUESDAY...MAINLY IN THE MORNING. TOTAL SNOW ACCUMULATIONS FOR MONDAY NIGHT THROUGH TUESDAY CURRENTLY FORECAST TO BE AN INCH OR LESS. WIND DOES NOT APPEAR THAT IT WILL BE A PROBLEM. THE REMAINDER OF THE PERIOD WILL BE DOMINATED BY NORTHWEST FLOW ALOFT. GFS SHOWS SOME VERY LIGHT SNOW OR FLURRIES WEDNESDAY NIGHT WITH SUBTLE SHORTWAVE IN THE FLOW...OTHERWISE DRY. TEMPERATURES WILL SLOWLY REBOUND FROM THE TUESDAY COOL DOWN...NEAR NORMAL WEDNESDAY AND THURSDAY THEN SLIGHTLY ABOVE NORMAL FRIDAY AND SATURDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 454 PM MST SAT JAN 26 2013 AT GLD...VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE TAF PERIOD. MID-LEVEL CLOUDS WILL PERSIST THROUGHOUT THE NIGHT WITH SOME LIGHT RAIN SHOWERS BEFORE MIDNIGHT. THERE IS A CHANCE OF MVFR VISIBILITIES TOWARDS DAWN DUE TO ABUNDANT LOW-LEVEL MOISTURE BUT AM NOT AS CONFIDENT IN FOG DEVELOPMENT AT GLD COMPARED TO MCK. AT MCK...VFR TO MVFR CONDITIONS TONIGHT...WITH A CHANCE FOR IFR VISIBILITIES TOMORROW MORNING. SHOWERS WILL REACH THE AREA LATER TONIGHT WITH MVFR CEILINGS LIKELY. PATCHY FOG IS EXPECTED WITH MVFR VISIBILITIES THROUGH THE EARLY MORNING. HELD OFF ON LOWERING VIS TO IFR LEVELS AT THIS TIME AS BELIEVE GUIDANCE IS TOO MOIST AT THE LOWEST LEVELS. BY LATE MORNING FOG WILL DISSIPATE AND CONDITIONS WILL BE VFR FOR THE REST OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...DR LONG TERM...024 AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
454 PM MST SAT JAN 26 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 135 PM MST SAT JAN 26 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW SHORTWAVE RIDGING ACROSS THE SOUTHERN PLAINS WITH A SERIES OF SHORTWAVE TROUGHS OVER SOUTHERN CALIFORNIA AND OFF THE PACIFIC NW COAST. THE FIRST OF THESE TROUGHS OVER SOUTHERN CALIFORNIA WILL BE THE MAIN WEATHER PRODUCER FOR US TONIGHT WITH MID-HIGH CLOUDS ALREADY INCREASING AHEAD OF THIS FEATURE OVER COLORADO AND WESTERN KS. GUIDANCE IN GENERAL AGREEMENT ON PRECIP SPREADING FROM THE WEST TO THE EAST THROUGH THE EVENING HOURS...WITH BEST COVERAGE/CHANCES ACROSS THE EAST/NORTHEAST AFTER MIDNIGHT AS A WARM FRONT MOVES NORTH AND MOISTURE ADVECTION INCREASES. IM NOT AS CONFIDENT ABOUT COVERAGE DURING THE EVENING WITH MOISTURE ADVECTION BELOW H7 MARGINAL UNTIL 06Z. NAM IS ADVERTISING DRY SLOT QUICKLY MOVING FROM THE W/SW LATE THIS EVENING THROUGH SUNDAY MORNING...AND WITH STRONG DRY SLOT ALREADY APPARENT ON WV IMAGERY THIS MAY BE REASONABLE. I HAVE TRENDED POPS HIGHER ACROSS THE NORTHEAST AROUND 06-12Z...AND HAVE DECREASED POPS QUICKER ACROSS THE SW DURING THIS SAME TIME PERIOD. OVERALL QPF AMOUNTS SHOULD BE LIGHT...WITH HIGHEST TOTALS IN SW NEBRASKA AND NORTH CENTRAL KS WHERE UP TO 0.10 INCHES OF LIQUID IS POSSIBLE. AS WITH PREVIOUS FORECASTS I KEPT PRECIP TYPE ALL RAIN WITH MODEL SOUNDINGS SUPPORTING ALL LIQUID...AND SURFACE TEMPERATURES EXPECTED TO REMAIN ABOVE FREEZING WHERE PRECIP/CLOUD COVER IS LINGERING AFTER MIDNIGHT. BELOW FREEZING TEMPS WILL BE POSSIBLE IN THE W/SW WHERE SKIES WILL BE CLEARING...HOWEVER PRECIP WILL BE OVER WITH AT THAT POINT. WITH INCREASING LOW LEVEL MOISTURE ACROSS THE NORTH AND EAST WE COULD ALSO SEE PATCHY FOG DEVELOPMENT LATE TONIGHT INTO SUNDAY MORNING BEFORE THE WARM FROM FINAL PUSHES NORTH INTO CENTRAL NEBRASKA BEFORE 18Z...WITH DRY/STABLE CONDITIONS EXPECTED THROUGH THE REST OF SUNDAY. WITH CLEARING SKIES...AND 10-14C H85 TEMPS ADVECTING OVER THE CWA FROM THE WEST WE SHOULD SEE ANOTHER MILD DAY WITH TEMPERATURES IN THE MIDDLE 60S IN THE SOUTH TO THE LOW 50S NEAR MCCOOK WHERE CLOUD COVER MAY LINGER LONGER INTO THE AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 135 PM MST SAT JAN 26 2013 MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH MONDAY. SYSTEM WILL MOVE THROUGH MONDAY NIGHT BRINGING A CHANCE OF LIGHT SNOW AND COLDER TEMPERATURES. THERE COULD BE A BRIEF PERIOD OF LIGHT RAIN AHEAD OF THE FRONT...BUT IT WILL QUICKLY CHANGE TO SNOW. LIGHT SNOW OR FLURRIES COULD LINGER INTO TUESDAY...MAINLY IN THE MORNING. TOTAL SNOW ACCUMULATIONS FOR MONDAY NIGHT THROUGH TUESDAY CURRENTLY FORECAST TO BE AN INCH OR LESS. WIND DOES NOT APPEAR THAT IT WILL BE A PROBLEM. THE REMAINDER OF THE PERIOD WILL BE DOMINATED BY NORTHWEST FLOW ALOFT. GFS SHOWS SOME VERY LIGHT SNOW OR FLURRIES WEDNESDAY NIGHT WITH SUBTLE SHORTWAVE IN THE FLOW...OTHERWISE DRY. TEMPERATURES WILL SLOWLY REBOUND FROM THE TUESDAY COOL DOWN...NEAR NORMAL WEDNESDAY AND THURSDAY THEN SLIGHTLY ABOVE NORMAL FRIDAY AND SATURDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 454 PM MST SAT JAN 26 2013 AT GLD...VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE TAF PERIOD. MID-LEVEL CLOUDS WILL PERSIST THROUGHOUT THE NIGHT WITH SOME LIGHT RAIN SHOWERS BEFORE MIDNIGHT. THERE IS A CHANCE OF MVFR VISIBILITIES TOWARDS DAWN DUE TO ABUNDANT LOW-LEVEL MOISTURE BUT AM NOT AS CONFIDENT IN FOG DEVELOPMENT AT GLD COMPARED TO MCK. AT MCK...VFR TO MVFR CONDITIONS TONIGHT...WITH A CHANCE FOR IFR VISIBILITIES TOMORROW MORNING. SHOWERS WILL REACH THE AREA LATER TONIGHT WITH MVFR CEILINGS LIKELY. PATCHY FOG IS EXPECTED WITH MVFR VISIBILITIES THROUGH THE EARLY MORNING. HELD OFF ON LOWERING VIS TO IFR LEVELS AT THIS TIME AS BELIEVE GUIDANCE IS TOO MOIST AT THE LOWEST LEVELS. BY LATE MORNING FOG WILL DISSIPATE AND CONDITIONS WILL BE VFR FOR THE REST OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...024 AVIATION...JJM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
403 PM EST FRI JAN 25 2013 .SYNOPSIS... FAST MOVING LOW PRESSURE WILL PIVOT ACROSS THE REGION THROUGH THIS EVENING. HIGH PRESSURE BUILDS IN FROM THE WEST LATE TONIGHT...AND PREVAILS OVER THE REGION OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... REGIONAL RADAR MOSAIC SHOWS BAND OF LIGHT TO MOD SNOW HAS PUSHED ACROSS AKQ CWA AS EXPECTED OVER THE PAST FEW HOURS, WITH AXIS DENOTING BACK END OF SIGNIFICANT SNOWFALL NOW SLIDING ACROSS FAR NORTHERN ZONES...AND SNOW ALREADY APPEARS TO BE DIMINISHING IN INTENSITY ACROSS FAR NORTHERN TIER OF CWA. DRY SLOT EVIDENT ON EARLY AFTERNOON WV SAT IMAGERY HAS ALREADY PUNCHED INTO THIS AREA...AND WHILE PDS OF LIGHT SNOW SHUD CONTINUE FOR ANOTHER FEW HRS, SNOWFALL TOTALS AOB 1" WILL BE COMMON OVER NORTHERN TIER OF THE AREA (INCLUDING SALISBURY, TAPPAHANNOCK, CRISFIELD). DUE TO EVENING RUSH HOUR UPCOMING, WL RETAIN WINTER WX ADVY OVER THESE AREAS, BUT ANTICIPATE HEADLINE MAY BE ABLE TO BE REDUCED IN AREAL COVERAGE SHORTLY THEREAFTER. FARTHER SOUTH, PDS OF STEADIER SNOW WILL CONTINUE OVER SOUTH CENTRAL/SOUTHEASTERN VA FOR ANOTHER 3-4 HOURS...WITH TOTAL ACCUMS LIKELY SETTLING BETWEEN 1-3" AS BEST FRONTOGENETIC FORCING DEVELOPS AND SWINGS ACROSS SOUTH CENTRAL VA OVER TO THE LOWER EASTERN SHORE. P-TYPE WL BECOME AN ISSUE MAINLY SOUTH OF US-58 W/INCREASING SSW FLOW. AN INTRUSION OF A WARM NOSE (WARM AIR ALOFT W/AIR TEMP >0C) BETWEEN H85-65. AS WE`VE SEEN TO THE WEST/SOUTHWEST ACROSS THE TN VLY THIS MORNING AND CENTRAL NC ERY THIS AFTN, A RESULTANT MIX OR CHANGE TO FZRA (MIXED WITH IP AT TIMES) IS EXPECTED OVER PARTS OF THE LOCAL AREA MAINLY ALONG AND S OF THE VA/NC BORDER, EVENTUALLY NOSING INTO EXTREME SE VA JUST BEFORE PCPN TAPERS OFF. WARM NOSE HAS ALREADY MADE MORE PROGRESS NORTH THAN MODELS ANTICIPATED AND THUS HV BEEN A BIT MORE GENEROUS THAN RUC DEPICTION OF THIS FEATURE THROUGH 05Z/MIDNIGHT. EXPECT THAT PORTIONS OF NE NC AWAY FROM THE ATLANTIC COAST AND THE ALBEMARLE SOUND SHOULD TRANSITION TO FREEZING RAIN AFTER 22Z, TAPERING OFF BY MIDNIGHT TO A PERIOD OF LGT FZDZ AS COLUMN DRYING CONTINUES THROUGH THE NIGHT FROM NW TO SE. ANY ICE ACCUMULATION SHOULD BE ON THE ORDER OF A TENTH OF AN INCH OR LESS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/... DRY WNW FLOW PREVAILS BEHIND THE SYSTEM OVER THE WEEKEND AS THE LOW RAPIDLY DEEPENS WELL OFFSHORE AND SURFACE HIGH PRESSURE REBUILDS FROM THE WEST. FORECAST MAXIMA GENERALLY RANGING FROM THE LOW/MID 30S N...TO AROUND 40 S (THESE VALUES AREA SLIGHTLY BELOW GUIDANCE BASED ON FORECAST SNOW COVER OVER MUCH OF THE AREA). SFC HIGH SLIDES OVERHEAD SUNDAY...SCOOTING OFFSHORE BY SUNDAY NIGHT/MON MORNING. HV AGAIN UNDERCUT GUIDANCE FOR HIGHS ON SUNDAY, WITH ANOTHER DRY DAY EXPECTED. HIGHS ONCE AGAIN M/U 30S TO NR 40. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... IN THE LONGER TERM...WHILE THE MODELS OVERALL SHOW A SIMILAR PATTERN WITH A DEVELOPING RIDGE OVER THE SOUTHEASTERN US TO START THE PERIOD ON SUNDAY NIGHT INTO MONDAY...THE MODELS STRUGGLE IN THE HANDLING OF THAT RIDGE AND AS A RESULT THE MODEL TIMING AND STRENGTH OF THE FRONT IS MUCH DIFFERENT IN THE 00Z AND 12Z MODELS. AT THIS TIME...HAVE LEANED MORE TOWARD THE NAM TIMING...WHICH IS CLOSER TO THE OVERALL PATTERN OF THE ECMWF. THE GFS IS SLOWER AND MORE AMPLIFIED THAN THE ECMWF AND WHILE IT CAN NOT BE DISCOUNTED...IT SEEMS LESS LIKELY. FOR SUNDAY NIGHT INTO MONDAY...THE MODELS SHOW A DEVELOPING WARM ADVECTION PATTERN AS THE SURFACE HIGH SETTLES OVER THE WESTERN ATLANTIC. AS THE SW FLOW ALOFT DEVELOPS AND MOISTURE INCREASES...COULD SEE SOME LIGHT PRECIP DEVELOP AFTER 6Z MONDAY THROUGH 18Z...MAINLY ACROSS NRN AND WESTERN SECTIONS OF THE CWA. THE BIG QUESTION IS THE SFC TEMPERATURES AS GUIDANCE SHOWS VALUES FALLING INTO THE MID TO UPPER 20S AS THE LOW LEVEL SATURATES. THIS COULD LEAD TO SOME LIGHT WINTRY PCPN. WILL NEED TO MONITOR THIS GOING FORWARD. BY MID AFTERNOON...SHOULD SEE ENOUGH WARM AREA MOVE INTO TO TURN ANY LINGER PCPN TO RAIN. THE RIDGE SHOULD AMPLIFY ENOUGH BY MON NIGHT AND TUESDAY TO PUSH THE SFC FRONT WELL TO THE NORTH AND TAKE THE ISENTROPIC LIFT TO THE NORTH AS WELL. THIS SHOULD ALLOW A 36 TO 48 HR WINDOW OF MILD AND DRY WEATHER. THE NEXT COLD FRONT STILL HAS LOTS OF QUESTIONS FROM STRENGTH TO TIMING. AT THIS POINT...HAVE CONTINUED THE IDEA THAT THE FRONT WILL CROSS THE REGION DURING THE DAY ON WEDNESDAY AND WITH A LESS AMPLIFIED UPPER TROUGH...WILL SEE MORE OF AN ANAFRONT BOUNDARY WITH OVERRUNNING RAIN. THE GFS GETS MUCH MORE AMPLIFIED AND SLOWS THE FRONT DOWN SO THAT IT COME THROUGH ON THURSDAY AND IS MUCH STRONGER. BUT FOR NOW...DO NOT SEE THE RATIONAL FOR THE STRONGER TROUGH AS THE PATTERN SEEMS TO BE MORE PROGRESSIVE. SO HAVE FOCUSED 50 POPS FOR WEDNESDAY AND THEN ALLOWED FOR MUCH DRIER AND COOLER AIR TO ARRIVE FOR THE END OF THE WEEK. THE 00Z ECMWF SHOWED A DEVELOPING SRN STREAM LOW AND MADE A MID ATLANTIC SNOW STORM FROM IT...BUT THE 12Z RUN BACKED OFF AND WITH THE MORE DOMINANT NRN STREAM IN PLACE...HAVE KEPT FRIDAY DRY AT THIS POINT. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... WARM ADVECTION PATTERN IS SETTING UP AND PRECIPITATION HAS SPREAD ACROSS WESTERN PORTIONS OF VIRGINIA AND NC AT THIS TIME. WATER VAPOR IMAGERY SHOWS STRONG JET DIVING SOUTHEASTWARD TOWARD THE MID ATLANTIC STATES WHICH SHOULD PROVIDE AN EXTRA ENHANCEMENT TO THE LIFT AS THE PRECIPITATION MOVES INTO EASTERN VA/NC. LOOKING AT UPSTREAM OBSERVATIONS...THE CEILINGS HAVE BEEN SLOW TO LOWER WITH THE INITIAL SNOW SO HAVE BEEN SLOWER TO LOWER THE CEILINGS HOLDING INITIALLY JUST ABOVE MVFR LEVELS BEFORE GRADUALLY LOWERING BELOW 1500 FT FOR RIC AND SBY SINCE THE LIFT AND CONSEQUENTLY THE SNOW FALL INTENSITY LOOKS TO BE LIGHTER. FOR PHF/ORF...WHERE THE LIFT IS STRONG AND THE PCPN INTENSITY LOOKS GREAT HAVE ALLOW FOR 500 TO 800 FT CEILINGS IN THE SNOW FOR SHORT 3 TO 4 HOUR WINDOW. ECG WILL BE IN THE BETTER LIFT AND PCPN AS WELL...BUT THE SOUNDINGS SHOW THAT ENOUGH WARM AIR AT AROUND 900 MB WILL PUSH NORTH CAUSING THE SNOW TO MELT ALLOWING FOR SOME IP/ZR TO DEVELOP BETWEEN 00Z AND 4Z. THE ENTIRE SYSTEM PUSHES OFF THE COAST BY 6Z WITH THE FLOW TURNING NORTHWEST...WHICH WILL PUSH DRIER AIR BACK INTO THE REGION. HIGH PRESSURE ARRIVES ON SATURDAY AND SLOWLY MOVES ACROSS THE AREA AND OFF THE EAST COAST BY MONDAY...WHILE PROVIDING VFR CONDITIONS. && .MARINE... HIGH PRESSURE WILL CONTINUE TO SLIDE OFFSHORE THROUGH THIS AFTN AND WINDS WILL BECOME SW 10-15 KT ON AVERAGE. A LOW PRESSURE SYSTEM WILL CROSS THE WATERS THIS EVENING AND STRENGTHEN AS IT MOVES JUST OFF THE MID ATLANTIC COAST TONIGHT. AS THIS OCCURS...WINDS WILL VEER TO THE NORTHWEST AND A SURGE OF SCA CONDITIONS (15-20 KT BAY/RIVERS...20-25 KT SOUND/OCEAN) SHOULD BE ANTICIPATED DURING THIS TIME. WAVES ON CHES BAY WILL INCREASE TO 3-4 FT AND SEAS WILL STAY AROUND 3-4 FT. BY SATURDAY MORNING THE LOW IS WELL OFFSHORE AND A SFC PRESSURE GRADIENT TIGHTENS ALONG THE COAST. THERE IS JUST ENOUGH INSTABILITY AND A DECENT TEMPERATURE GRADIENT THAT DEVELOPS TO CONTINUE SCA FLAGS THROUGH SAT INTO SAT NIGHT BEFORE WINDS AND SEAS SUBSIDE. WAVE ON CHES BAY WILL AGAIN BE 3-4 FT ON AVERAGE AND SEAS WILL QUICKLY BUILD TO 4-6 FT SAT MORNING. IN NORTHWEST FLOW...SEAS WILL BE SLOW TO SUBSIDE AND SHOULD HOVER AROUND 5 FT NEAR 20 NM UNTIL EARLY SUN MORNING. HIGH PRESSURE BUILDS IN FROM THE NORTHWEST ON SUNDAY AND GRADUALLY SLIDES SOUTHEAST OFF THE WRN ATLANTIC COAST EARLY NEXT WEEK. QUIET CONDITIONS ARE ANTICIPATED DURING THIS TIME AS WINDS AVERAGE 10-15 KT... WITH NW WINDS ON SUN...BECOMING S-SW MON THROUGH WED. THE NEXT LOW PRESSURE SYSTEM APPROACHES THE REGION DURING THE MID TO LATE WEEK TIMEFRAME. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR MDZ021>025. NC...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR NCZ012>017- 030>032-102. VA...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR VAZ065-066- 077>082-084>100. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR VAZ060-063-064-067-068-070>076-083. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST SUNDAY FOR ANZ652-654-656-658. SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO 6 AM EST SUNDAY FOR ANZ650. SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO MIDNIGHT EST SATURDAY NIGHT FOR ANZ636. SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST SUNDAY FOR ANZ630>634. SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EST SATURDAY FOR ANZ635. SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 6 AM EST SUNDAY FOR ANZ638. && $$ SYNOPSIS...MAM NEAR TERM...AJZ/MAM SHORT TERM...AJZ/MAM LONG TERM...TMG AVIATION...ESS MARINE...BMD
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1250 PM EST FRI JAN 25 2013 .AVIATION... //DISCUSSION... THE INITIAL WAVE OF MOISTURE FOR LIGHT SNOW WILL RUN ITS COURSE IN THE DETROIT AREA DURING THE EARLY AFTERNOON LEAVING AT LEAST INTERVALS OF VFR CONDITIONS. LIGHT SNOW WILL LINGER FOR A GREATER PART OF THE DAY FROM FNT NORTHWARD MOSTLY IN MVFR BUT WITH INTERVALS OF IFR DUE TO VISIBILITY RESTRICTION. THE APPROACH OF SURFACE LOW PRESSURE TONIGHT, AND THE ASSOCIATED CONVERGENT LOW LEVEL FLOW, WILL MIX WITH LAKE MOISTURE TO BRING MVFR CEILING TO ALL AREAS. RESIDUAL LIGHT SNOW IS EXPECTED TO AFFECT MAINLY THE FNT TO MBS AREA DURING THE EVENING BEFORE PASSAGE OF THE LOW BRINGS THE WIND AROUND TO THE NORTHWEST BY MID SATURDAY MORNING. INITIAL INDICATIONS ARE THAT THE LOW LEVEL WIND PATTERN WILL BE DRY AND NEUTRAL ENOUGH TO HELP BREAK UP MVFR CEILING FOR THE REST OF THE DAY. FOR DTW... WIDELY VARYING CONDITIONS DURING THE AFTERNOON AND EVENING WILL BE FIRST MARKED BY SNOW DIMINISHING WITH LITTLE OR NO ADDITIONAL ACCUMULATION. A PERIOD OF VFR CONDITIONS, BUT WITH CEILING BELOW 5000 FEET, WILL BE LEFT BEHIND FOR THE MID TO LATE AFTERNOON BEFORE MVFR CEILING RETURNS AS LOW PRESSURE CROSSES CENTRAL LOWER MICHIGAN TONIGHT. ANY ADDITIONAL SNOW SHOWERS ARE EXPECTED TO REMAIN NORTH OF DTW TONIGHT. DEVELOPMENT OF NORTHWEST WIND OVERNIGHT THROUGH SATURDAY MORNING WILL HELP IMPROVE CEILING BY SATURDAY AFTERNOON. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILING BELOW 5000 FEET THIS AFTERNOON AND TONIGHT. && .PREV DISCUSSION...ISSUED 1103 AM EST FRI JAN 25 2013 UPDATE... EXPECT LIGHT SNOW TO DIMINISH DURING THE AFTERNOON, ESPECIALLY IN THE DETROIT AREA WHERE SYSTEM RELATIVE ISENTROPIC LIFT WILL BE ON THE WANE. AN INFUSION OF DRY AIR WILL BE THE EVIDENCE OF MID LEVEL THETA-E DISRUPTION WITH THE MODEST DRY SLOT POSSIBLY REACHING AS FAR NORTH AS FLINT BUT LIKELY NOT AS FAR NORTH AS THE TRI CITIES BEFORE THE UPPER LEVEL WAVE APPROACHES FROM WISCONSIN TOWARD EVENING. EXPECT THIS WAVE TO RENEW ISENTROPIC LIFT AHEAD OF ITS TRACK AND BRING A COMPONENT OF DYNAMIC FORCING THAT WILL HELP BOOST COVERAGE OF LIGHT SNOW BUT AGAIN AFFECTING MAINLY THE TRI CITIES AND NORTHERN THUMB DURING THE EVENING. THIS UPDATE WILL ADDRESS THE DIMINISHING TREND IN THE DETROIT AREA WITH AFTERNOON OBSERVATIONS UPSTREAM HELPING ADDRESS EVENING EXPECTATIONS WITH THE AFTERNOON PACKAGE. PREV DISCUSSION...ISSUED 342 AM EST FRI JAN 25 2013 SHORT TERM...TODAY AND TONIGHT AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN. WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO 0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z. THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE. ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL ACCUMULATION IS EXPECTED AFTER 18Z. CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE. LONG TERM...SATURDAY THROUGH THURSDAY BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE EXPANDING LOW TO MID LEVEL ANTICYCLONIC FLOW FILLING ACROSS THE UPPER MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET /DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS. MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM... TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION... WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD /MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG) INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF ACROSS THE SOUTH IS ATTAINABLE. LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT WEEK. MARINE... AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT UPDATE.......BT SHORT TERM...KURIMSKI LONG TERM....MR MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1103 AM EST FRI JAN 25 2013 .UPDATE... EXPECT LIGHT SNOW TO DIMINISH DURING THE AFTERNOON, ESPECIALLY IN THE DETROIT AREA WHERE SYSTEM RELATIVE ISENTROPIC LIFT WILL BE ON THE WANE. AN INFUSION OF DRY AIR WILL BE THE EVIDENCE OF MID LEVEL THETA-E DISRUPTION WITH THE MODEST DRY SLOT POSSIBLY REACHING AS FAR NORTH AS FLINT BUT LIKELY NOT AS FAR NORTH AS THE TRI CITIES BEFORE THE UPPER LEVEL WAVE APPROACHES FROM WISCONSIN TOWARD EVENING. EXPECT THIS WAVE TO RENEW ISENTROPIC LIFT AHEAD OF ITS TRACK AND BRING A COMPONENT OF DYNAMIC FORCING THAT WILL HELP BOOST COVERAGE OF LIGHT SNOW BUT AGAIN AFFECTING MAINLY THE TRI CITIES AND NORTHERN THUMB DURING THE EVENING. THIS UPDATE WILL ADDRESS THE DIMINISHING TREND IN THE DETROIT AREA WITH AFTERNOON OBSERVATIONS UPSTREAM HELPING ADDRESS EVENING EXPECTATIONS WITH THE AFTERNOON PACKAGE. && .AVIATION...ISSUED 601 AM EST FRI JAN 25 2013 //DISCUSSION... LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES WILL ALLOW AN AREA OF SNOWFALL TO OVERSPREAD SOUTHEAST MICHIGAN TODAY. POCKETS OF LIGHT SNOW WILL BEGIN TO EMERGE THIS MORNING AS THE LOWER LAYERS GRADUALLY SATURATE. CONDITIONS WILL LOWER TO IFR/MVFR 16Z-20Z AS SNOWFALL INCREASES IN COVERAGE AND INTENSITY. MVFR CONDITIONS WILL LINGER INTO THE EVENING AS LIGHT SNOW SHOWERS CONTINUE ACROSS SOUTHEAST MICHIGAN. SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE ARE EXPECTED FROM THIS SYSTEM. FOR DTW...A BRIEF BURST OF LIGHT SNOW REMAINS POSSIBLE THIS MORNING...BUT UPSTREAM TRENDS SUGGEST THE GREATER POTENTIAL WILL EXIST AROUND MIDDAY /16-20Z/. //DTW THRESHOLD THREATS... * MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FEET THIS MORNING...HIGH CONFIDENCE THIS AFTERNOON. && .PREV DISCUSSION...ISSUED 342 AM EST FRI JAN 25 2013 SHORT TERM...TODAY AND TONIGHT AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN. WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO 0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z. THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE. ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL ACCUMULATION IS EXPECTED AFTER 18Z. CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE. LONG TERM...SATURDAY THROUGH THURSDAY BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE EXPANDING LOW TO MID LEVEL ANTICYCLONIC FLOW FILLING ACROSS THE UPPER MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET /DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS. MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM... TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION... WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD /MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG) INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF ACROSS THE SOUTH IS ATTAINABLE. LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT WEEK. MARINE... AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......BT AVIATION.....MR SHORT TERM...KURIMSKI LONG TERM....MR MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
601 AM EST FRI JAN 25 2013 .AVIATION... //DISCUSSION... LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES WILL ALLOW AN AREA OF SNOWFALL TO OVERSPREAD SOUTHEAST MICHIGAN TODAY. POCKETS OF LIGHT SNOW WILL BEGIN TO EMERGE THIS MORNING AS THE LOWER LAYERS GRADUALLY SATURATE. CONDITIONS WILL LOWER TO IFR/MVFR 16Z-20Z AS SNOWFALL INCREASES IN COVERAGE AND INTENSITY. MVFR CONDITIONS WILL LINGER INTO THE EVENING AS LIGHT SNOW SHOWERS CONTINUE ACROSS SOUTHEAST MICHIGAN. SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE ARE EXPECTED FROM THIS SYSTEM. FOR DTW...A BRIEF BURST OF LIGHT SNOW REMAINS POSSIBLE THIS MORNING...BUT UPSTREAM TRENDS SUGGEST THE GREATER POTENTIAL WILL EXIST AROUND MIDDAY /16-20Z/. //DTW THRESHOLD THREATS... * MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FEET THIS MORNING...HIGH CONFIDENCE THIS AFTERNOON. && .PREV DISCUSSION...ISSUED 342 AM EST FRI JAN 25 2013 SHORT TERM...TODAY AND TONIGHT AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN. WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO 0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z. THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE. ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL ACCUMULATION IS EXPECTED AFTER 18Z. CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE. LONG TERM...SATURDAY THROUGH THURSDAY BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE EXPANDING LOW TO MID LEVEL ANTICYLONIC FLOW FILLING ACROSS THE UPPER MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET /DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS. MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM... TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION... WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD /MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG) INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF ACROSS THE SOUTH IS ATTAINABLE. LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT WEEK. MARINE... AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....99 SHORT TERM...KURIMSKI LONG TERM....MR MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
342 AM EST FRI JAN 25 2013 .SHORT TERM...TODAY AND TONIGHT AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN. WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO 0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z. THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE. ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL ACCUMULATION IS EXPECTED AFTER 18Z. CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE. && .LONG TERM...SATURDAY THROUGH THURSDAY BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE EXPANDING LOW TO MID LEVEL ANTICYLONIC FLOW FILLING ACROSS THE UPPER MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET /DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS. MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM... TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION... WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD /MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG) INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF ACROSS THE SOUTH IS ATTAINABLE. LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT WEEK. && .MARINE... AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST. && .AVIATION...ISSUED 1216 AM EST FRI JAN 25 2013 //DISCUSSION... AN APPROACHING CLIPPER SYSTEM WILL BRING LIGHT SNOW TO THE TAF SITES LATER THIS MORNING AS IT TRACKS THROUGH THE CENTRAL GREAT LAKES REGION. REGIONAL 00Z RAOB SOUNDINGS SHOW QUITE A BIT OF DRY AIR NEEDS TO BE OVERCOME BEFORE SNOW CAN START...WITH THE RECENT NAM RUN DEPICTING THIS LATER START AND LOWER SNOWFALL AMOUNTS QUITE WELL. WILL DELAY THE ONSET OF SNOWFALL AT THE TAF SITES THIS MORNING WITH SNOW EXPECTED TO START AT MBS AROUND 10Z AND THE METRO AIRPORTS AROUND 12-13Z. THIS EVENT IS EXPECTED TO BRING WIDESPREAD MVFR CONDITIONS AND OCCASIONAL IFR VSBYS IN THE HEAVIER SNOW BANDS. MVFR CONDITIONS WILL LINGER THIS AFTERNOON AND INTO THE EVENING AS LIGHT SNOW SHOWERS CONTINUE ACROSS SOUTHEAST MICHIGAN. SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE ARE EXPECTED FROM THIS SYSTEM. FOR DTW...CEILINGS AND VISIBILITIES WILL DIMINISH QUICKLY AFTER THE SNOW BEGINS AFTER 12Z. SNOW WILL START OUT LIGHT AND GRADUALLY INTENSIFY AFTER 16Z. LIGHT SNOW WILL CONTINUE THROUGH THE AFTERNOON AND EVENING HOURS. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE THAT PRECIPITATION TYPE WILL REMAIN ALL SNOW DURING THE TAF PERIOD. * HIGH CONFIDENCE FOR CEILINGS TO DROP BELOW 5000 FEET AFTER 12Z THIS MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...KURIMSKI LONG TERM....MR MARINE.......KURIMSKI AVIATION.....KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
438 AM CST FRI JAN 25 2013 .DISCUSSION... TODAY AND TONIGHT...WEAK CLIPPER-TYPE LOW OVER NRN MN THIS MRNG WILL SHIFT E ACROSS THE GREAT LAKES THROUGH TNGT...DRAGGING A CDFNT ACROSS MN AND WI. EARLY MRNG LGT SNOW OVER ERN PORTIONS OF THE MPX CWFA HAVE QUICKLY DISSIPATE...OWING TO MUCH DRIER AIR BEING ADVECTED INTO THE REGION IN ADVANCE OF THE CDFNT. AS THE LOW PRES CENTER SHIFTS AWAY...SKIES WILL PARTIALLY CLEAR OUT BUT LITTLE TO NO WARMING IS EXPECTED WITH THE ADDITIONAL SUNSHINE DUE TO THE SFC FROPA. TEMPS WILL REMAIN FAIRLY STNRY DURG THE DAY TDA THEN DECRS RAPIDLY LATE DAY THRU THE EVENING AS ANOTHER ARCTIC HIGH PRES AIRMASS MOVES INTO THE REGION. HIGHS TDA THAT GENERALLY REACH THE TEENS WILL DROP TO THE SINGLE DIGITS BELOW ZERO TNGT FOR LOWS. HAVE BEEN ABLE TO CANCEL THE WINTER WX ADVY THIS MRNG SINCE ANY ADDITIONAL SNOW ACCUM WILL BE AN INCH OR LESS...AND WILL NOT NEED A WIND CHILL ADVY TNGT SINCE WINDS WILL DROP OFF AS THE INCOMING AREA OF HIGH PRES CENTERS ITSELF OVER THE AREA. THAT SAID...WIND CHILL VALUES WILL STILL LIKELY DROP TO BETWEEN -10 AND -20 OVERNIGHT. SATURDAY THROUGH MONDAY...THE AREA OF SFC HIGH PRES WILL QUICKLY EXIT TO THE E SAT BUT WILL BE FOLLOWED BY A LARGE SCALE UPPER LEVEL RIDGE AXIS THAT WILL CROSS THE REGION SAT INTO SUN. THE SLY FLOW ON THE BACKSIDE OF THE HIGH COMBINED WITH MUCH ELEVATED H5 HEIGHTS THRU THE WEEKEND INTO EARLY NEXT WEEK TRANSLATE INTO A NOTICEABLE WARMING TREND OVER THE WEEKEND INTO NEXT WEEK. HIGHS WILL REACH THE UPR 20S TO LWR 30S ON SUN FOLLOWED BY LOW-MID 30S ON MON. THE COMPLICATING FACTOR IS THAT A PAIR OF WEAK LOW PRES SYSTEMS...ONE TO THE S AND ONE TO THE N...WILL MOVE WITHIN CLOSE PROXIMITY OF THE MPX CWFA TO PRODUCE ISOLD TO SCTD AREAS OF PRECIP AND IT IS NOT WELL-DEFINED WHAT THE P-TYPES WILL BE FOR THE ENTIRE TIME. DURING THE TIMES THAT SFC TEMPS APCH THE FREEZING MARK... MODEL SOUNDINGS AND SREF PROGS INDICATE A STRONG POSSIBILITY OF FZRA RATHER THAN IP OR A RAIN/SNOW MIX SO HAVE INCLUDED MENTION OF FZRA FOR A FEW PERIODS THRU THE WEEKEND. IN ADDITION...THE WEAKENED STRENGTH OF THE LOW PRES SYSTEMS WILL FORCE POPS NO HIGHER THAN MID-CHC RANGE THROUGH THIS PERIOD OF THE FCST. TUESDAY THROUGH THURSDAY...BY TUE...THE OVERALL UPPER LEVEL PATTERN CHANGES FROM A RIDGE OVER THE CENTRAL CONUS TO A DEVELOPING TROF OVER THE WRN CONUS THAT WILL SHIFT E THROUGH MIDWEEK. THIS WILL ALLOW FOR AN ELONGATED LOW PRES AREA FROM THE SRN GREAT LAKES TO THE TX/OK PANHANDLE TO GRADUALLY SHIFT E. MOST OF THE FOCUS FOR PRECIP WILL BE ON THE SRN AND ERN PORTIONS OF THE CWFA FOR TUE. AS THIS COMPLEX SYSTEM MOVES OUT WED INTO THU...THE CENTRAL TROUGH AXIS WILL SWING THRU THE CENTRAL CONUS...OPENING THE DOOR TO NW FLOW THAT WILL BRING DOWN ANOTHER ARCTIC HIGH PRES AIRMASS FOR WED INTO THU. THIS WILL DROP HIGH TEMPS FROM THE 20S- 30S ON TUE BACK DOWN TO THE SINGLE DIGITS ON WED-THU. IN TURN... LOW TEMPS WILL DROP TO THE 5 TO 15 DEGREES BELOW ZERO RANGE. && .AVIATION.../06Z TAF ISSUANCE/ DRY AIR IS BEATING OUT THE SNOWFALL...AND CONFIDENCE IN IT OCCURRING AT ANY OF THE TERMINALS IS CLOSE TO NIL. PROBLEM HAS BEEN A DISCONNECT BETWEEN MID/UPPER LEVEL MOISTURE AND LOW LEVEL MOISTURE. NAMELY...AS THE LATER FINALLY SHOWS UP...THE FORMER DEPARTS AS A DRY SLOT MOVES OVERHEAD. BEST CHANCE FOR SNOW WHEN LOOKING AT THE RAP WOULD BE EAU...BUT EVEN HERE ONLY EXPECT A DUSTING...WITH MVFR VIS RESTRICTIONS AT WORST. FOR CIGS...MVFR CIGS HAVE BEEN CONFINED CLOSER TO THE SFC LOW...WHICH AT 6Z WAS OVER NE NODAK AND WILL BE OVER NRN WI BY 15Z. LOW CIGS SHOULD BE CONFINED CLOSER TO THE LOW AND WILL LIKELY PUT NRN TERMINALS ON SRN EDGE OF MVFR CIGS DURING THE DAY FRIDAY. CLEARING MOVING IN QUICKLY ACROSS NORTH CENTRAL NODAK ALSO LEADING TO LESS CONFIDENCE ON WHAT WILL HAPPEN WITH CIGS TOMORROW. WHERE THERE STILL IS HIGH CONFIDENCE IS WITH GUSTY NW WINDS FRIDAY. CAA DURING THE AFTERNOON WILL PROMOTE STEEP LAPSE RATES AND EFFICIENT MIXING OF WINDS DOWN FROM 3K FT...WHICH SHOULD PROMOTE NW GUSTS TO 35 KTS IN WRN MN DURING THE LATE MORNING AND TO 30 KTS ACROSS ERN MN AND WRN WI IN THE EARLY AFTERNOON. AFTER 00Z...SKIES WILL BE QUICKLY CLEARING OUT AND WINDS CALMING DOWN. KMSP...HAVE REMOVED SNOW MENTION FROM THE TAF...THOUGH A FEW FLURRIES CAN NOT BE RULED OUT THROUGH 8Z...BUT DO NOT ANTICIPATE AND VIS RESTRICTIONS. CIGS DO NOT LOOK TO LOWER TO MVFR LEVELS UNTIL AROUND 12Z AS CIGS CURRENTLY UP BY FARGO MOVE INTO THE TWIN CITIES. LOTS OF UNCERTAINTY WITH HOW LONG RESTRICTED CIGS WILL HANG AROUND...BUT ENHANCED MIXING WITH BARE GROUND MAY SUPPORT A MORE ROBUST POST FRONTAL STRATO CU FIELD THAN AREAS TO THE N/W...KEEPING MVFR CIGS IN PLACE THROUGH THE AFTERNOON. WITH WINDS...TRANSITION TO THE NW WILL HAPPEN DURING THE MORNING RUSH...MAKING THE TRANSITION OF AIRPORT OPERATIONS FROM THE 15S TO THE 30S TRICKY. SEEING PLENTY OF GUST POTENTIAL FOR TOMORROW AND MAY SEE A GUST OR TWO APPROACH 35 KTS AROUND 18Z AS INITIAL SURGE OF COLD AIR MOVES IN. /OUTLOOK FOR KMSP/ SAT...VFR. SE WINDS AT 5-10 KTS. SUN...MVFR WITH IFR AND -SN/FZRA/RA POSSIBLE. WINDS SE 10 KTS. MON...MVFR/IFR CIGS POSSIBLE. WINDS SE 4-8 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPC/BORGHOFF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1150 PM CST THU JAN 24 2013 .UPDATE... /ISSUED 818 PM CST THU JAN 24 2013/ QUICK UPDATE ON THE SNOWFALL POTENTIAL FOR TONIGHT...OR TO SAY IT BETTER...THE LACK THERE OF. LOW LEVEL DRY AIR HAS BEEN A SIGNIFICANT ISSUE TONIGHT...WITH SNOW STRUGGLING TO MAKE IT TO THE GROUND. LOOKING AT FORECAST SOUNDINGS FROM THE RAP...ABOUT THE TIME THE LOW LEVELS SATURATE...THE MID LEVELS DRY OUT AS A RATHER PRONOUNCED DRY SLOT ON WATER VAPOR FROM THE DAKOTAS INTO NRN MN MOVES OVERHEAD. ALL OF THIS IS REALLY WORKING HARD AGAINST OUR SNOW TONIGHT...AND CONFIDENCE IN SNOW FALLING ANYWHERE WITHIN THE MN PORTION OF THE CWA IS PLUMMETING. IN FACT...BASED ON CURRENT RAP...25.00 NAM ROLLING IN...AND HOPKINS WRF MEMBERS...MAY BE JUST A STRUGGLE TO GET AN INCH OF SNOW ACROSS OUR ADVY COUNTIES IN WI AS ALL OF THESE MODELS KEEP THE SNOW NORTH AND EAST OF THE MPX CWA. WILL NOT CHANGE THE ADVY AT THIS POINT...THOUGH WILL PROBABLY BE TRENDING POPS AND SNOWFALL AMOUNTS DOWNWARD SHORTLY. && .AVIATION.../06Z TAF ISSUANCE/ DRY AIR IS BEATING OUT THE SNOWFALL...AND CONFIDENCE IN IT OCCURRING AT ANY OF THE TERMINALS IS CLOSE TO NIL. PROBLEM HAS BEEN A DISCONNECT BETWEEN MID/UPPER LEVEL MOISTURE AND LOW LEVEL MOISTURE. NAMELY...AS THE LATER FINALLY SHOWS UP...THE FORMER DEPARTS AS A DRY SLOT MOVES OVERHEAD. BEST CHANCE FOR SNOW WHEN LOOKING AT THE RAP WOULD BE EAU...BUT EVEN HERE ONLY EXPECT A DUSTING...WITH MVFR VIS RESTRICTIONS AT WORST. FOR CIGS...MVFR CIGS HAVE BEEN CONFINED CLOSER TO THE SFC LOW...WHICH AT 6Z WAS OVER NE NODAK AND WILL BE OVER NRN WI BY 15Z. LOW CIGS SHOULD BE CONFINED CLOSER TO THE LOW AND WILL LIKELY PUT NRN TERMINALS ON SRN EDGE OF MVFR CIGS DURING THE DAY FRIDAY. CLEARING MOVING IN QUICKLY ACROSS NORTH CENTRAL NODAK ALSO LEADING TO LESS CONFIDENCE ON WHAT WILL HAPPEN WITH CIGS TOMORROW. WHERE THERE STILL IS HIGH CONFIDENCE IS WITH GUSTY NW WINDS FRIDAY. CAA DURING THE AFTERNOON WILL PROMOTE STEEP LAPSE RATES AND EFFICIENT MIXING OF WINDS DOWN FROM 3K FT...WHICH SHOULD PROMOTE NW GUSTS TO 35 KTS IN WRN MN DURING THE LATE MORNING AND TO 30 KTS ACROSS ERN MN AND WRN WI IN THE EARLY AFTERNOON. AFTER 00Z...SKIES WILL BE QUICKLY CLEARING OUT AND WINDS CALMING DOWN. KMSP...HAVE REMOVED SNOW MENTION FROM THE TAF...THOUGH A FEW FLURRIES CAN NOT BE RULED OUT THROUGH 8Z...BUT DO NOT ANTICIPATE AND VIS RESTRICTIONS. CIGS DO NOT LOOK TO LOWER TO MVFR LEVELS UNTIL AROUND 12Z AS CIGS CURRENTLY UP BY FARGO MOVE INTO THE TWIN CITIES. LOTS OF UNCERTAINTY WITH HOW LONG RESTRICTED CIGS WILL HANG AROUND...BUT ENHANCED MIXING WITH BARE GROUND MAY SUPPORT A MORE ROBUST POST FRONTAL STRATO CU FIELD THAN AREAS TO THE N/W...KEEPING MVFR CIGS IN PLACE THROUGH THE AFTERNOON. WITH WINDS...TRANSITION TO THE NW WILL HAPPEN DURING THE MORNING RUSH...MAKING THE TRANSITION OF AIRPORT OPERATIONS FROM THE 15S TO THE 30S TRICKY. SEEING PLENTY OF GUST POTENTIAL FOR TOMORROW AND MAY SEE A GUST OR TWO APPROACH 35 KTS AROUND 18Z AS INITIAL SURGE OF COLD AIR MOVES IN. /OUTLOOK FOR KMSP/ SAT...VFR. SE WINDS AT 5-10 KTS. SUN...MVFR WITH IFR AND -SN/FZRA/RA POSSIBLE. WINDS SE 10 KTS. MON...MVFR/IFR CIGS POSSIBLE. WINDS SE 4-8 KTS. && .PREV DISCUSSION... /ISSUED 540 PM CST THU JAN 24 2013/ A WEAK CLIPPER SYSTEM WILL MOVE THROUGH TONIGHT AND THE NEXT COUPLE OF DAYS WILL CONTINUE TO BE COLD. A BRIEF WARM UP EXPECTED THIS WEEKEND WITH A SECOND CHANCE FOR PRECIPITATION. THIS WILL BE FOLLOWED BY A THIRD STORM SYSTEM EARLY NEXT WEEK...AND ANOTHER SURGE OF ARCTIC AIR FOR THE END OF THE PERIOD. TONIGHT AND FRIDAY...EARLY AFTERNOON WATER VAPOR IMAGERY TOGETHER WITH 500MB HEIGHTS AND WINDS IDENTIFIED A SHORTWAVE TROUGH ALONG THE MONTANA/CANADA BORDER...WITH ANOTHER CUT OFF LOW OFF THE CALIFORNIA COAST...AND BROAD ALEUTIAN LOW IN THE GULF OF ALASKA. THE PV ANOMALY ASSOCIATED WITH THE FIRST FEATURE WILL MOVE NORTH OF THE REGION...WITH QVECT CONVERGENCE AND HEIGHT FALLS PROVIDING WIDESPREAD FORCING FOR UPPER LEVEL ASCENT. THE FRONTOGENETIC SIGNATURE IS RATHER BENIGN...SO NOT EXPECTING ANY AREAS OF MODERATE OR HEAVY SNOW TO DEVELOP. HOWEVER...FORECAST SOUNDINGS SHOW SATURATION FROM 03-09Z TONIGHT...SO SHOULD SEE AT LEAST SOME LIGHT SNOW DURING THIS TIME PERIOD. HIRES MODELS SEEM TO HAVE A GOOD HANDLE ON THE FAST MOVING AREA OF LIGHT PRECIP...AND WITH SNOW RATIOS OF 20-25:1 EXPECTING AS MUCH AS 2 TO 4 INCHES IN WESTERN WISCONSIN NEAR EAU CLAIRE/LADYSMITH AREA. LIGHT SNOW WILL LIKELY LINGER ACROSS WEST CENTRAL WI COUNTIES ON FRIDAY MORNING ON THE WESTERN PERIPHERY OF THE TROUGH AS IT MOVES ACROSS THE GREAT LAKES. COLD AIR ADVECTION WILL FOLLOW IN THE WAKE OF THIS SYSTEM AND KEEP THE BOUNDARY LAYER WELL MIXED...WITH SUSTAINED NORTHWEST WINDS OF 20 MPH...AND GUSTS NEAR 30 MPH BEGINNING LATE MORNING AND LASTING THROUGH FRIDAY AFTERNOON. THIS COULD CAUSE SOME BLOWING DRIFTING OF ANY SNOW THAT HAS FALLEN. THE DIURNAL TEMP TREND WILL BE A BIT ABNORMAL ON FRIDAY DUE TO THE MORNING FRONTAL PASSAGE. WILL LIKELY SEE FALLING TEMPS IN THE MORNING...FOLLOWED BY NEARLY STEADY TO ONLY SLIGHTLY WARMING READINGS IN THE AFTERNOON. SURFACE HIGH PRESSURE SETS IN FRIDAY EVENING...WITH ATTENDANT CLEAR SKIES AND LIGHT WINDS FOSTERING ANOTHER COLD NIGHT. ANTICIPATE LOWS TO DIP TO NEAR 15 BELOW /NORTHWEST NEAR KAXN/ TO 5 BELOW /SOUTHEAST NEAR KMSP AND KEAU/. WIND CHILL VALUES ARE NOT ANTICIPATED TO QUITE REACH ADVISORY CRITERIA DUE TO THE EXPECTED LIGHT WIND SPEEDS. OVER THE UPCOMING WEEKEND...THE LARGE SCALE FLOW PATTERN EVOLVES TO MORE OF A WEST/SOUTHWEST DIRECTIONAL COMPONENT. THIS SHOULD YIELD TEMPERATURE MODERATION INTO THE 15 TO 20 DEGREE RANGE FOR HIGHS SATURDAY...WITH LITTLE IN THE WAY OF A DROP OFF ON SATURDAY NIGHT...WHEN LOWS ARE GENERALLY EXPECTED TO RANGE BETWEEN 10 AND 15 DEGREES ABOVE ZERO. ALTHOUGH A FAIR AMOUNT OF CLOUDS WILL STREAM NORTH INTO THE AREA ON SUNDAY...SHOULD STILL BE ABLE TO WARM INTO THE 25 TO 35 DEGREE RANGE. HOWEVER...THE INFILTRATION OF WARMER AIR WILL LIKELY BE ACCOMPANIED BY A THREAT FOR OCCASIONAL FREEZING PRECIPITATION FROM SUNDAY NIGHT INTO TUESDAY...AS A SURFACE TROUGH NOSES INTO THE UPPER MIDWEST. THIS THREAT APPEARS THE GREATEST FROM SOUTHERN/EASTERN MN INTO WEST CENTRAL WI...AS SUPPORTED BY THE SREF PROBABILITY OF FREEZING RAIN PROGS. FORECAST CONFIDENCE REGARDING A POTENTIAL SYSTEM FOR EARLY NEXT WEEK IS NOT AS HIGH AS WAS HOPED FOR...AFTER INSPECTION OF THE 12Z ECMWF...WHICH ESSENTIALLY ERASED ITS DEPICTION OF A SUB-1000 MB SURFACE LOW JUST PASSING JUST SOUTHEAST OF THE FORECAST AREA ON TUESDAY. THE 12Z GEM AND GFS SOLUTIONS...ALTHOUGH DIFFERING A BIT IN THE PATH...ALSO FEATURED A DECENT /SNOW-MAKER/ SYSTEM AFFECTING THE FORECAST AREA ON TUESDAY. DUE TO THE INCONSISTENCY IN THE MODELS...DID NOT GO WITH LIKELY POPS AT THIS POINT...BUT DID INCLUDE HIGH CHANCE POPS FOR PRECIPITATION ON MONDAY NIGHT AND TUESDAY. PRECIP TYPE ALSO LOOKS TO BE POTENTIALLY MIXED/FREEZING...BUT THAT WILL DEPEND ON HOW THE SYNOPTICS EVOLVE. IN THE WAKE OF THE POTENTIAL SYSTEM...COLD AIR WILL AGAIN INFILTRATE THE REGION...WITH HIGHS AROUND 15 TO 20 DEGREES BELOW CLIMATOLOGICAL NORMALS FOR WEDNESDAY AND THURSDAY. FURTHERMORE...LOW TEMPERATURES WILL LIKELY DROP TO BETWEEN ZERO AND 15 BELOW FOR WEDNESDAY AND THURSDAY NIGHTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR BARRON- CHIPPEWA-RUSK. && $$ LS/MPG
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
849 PM CST SAT JAN 26 2013 .UPDATE... ISSUED AT 845 PM CST SAT JAN 26 2013 OVER THE LAST FEW HOURS AREA OF OVERRUNNING RAIN HAS DEVELOPED FROM SOUTHERN KANSAS INTO N OK. THIS AREA SHOULD CONTINUE TO EXPAND INTO OUR CWA DURING THE PREDAWN HOURS AND EARLY SUNDAY AS ZONE OF ISENTROPIC LIFT STRENGHTENS AND EXPANDS NORTHEAST WITH INTENSIFYING LOW LEVEL JET. OVERALL...GOING FORECAST IS LOOKING EXCELLENT. BASED ON REGIONAL RADAR TRENDS AND LATEST HRRR AND NAM WE MAY BE BRINGING THE PRECIP INTO OUR AREA A BIT TOO FAST BUT IT WOULD APPEAR THAT DIFFERENCE WOULD ONLY BE ON THE ORDER OF AN HOUR OR TWO...AND HAVE MADE THIS VERY SUBTLE TWEEK TO HOURLY POP GRIDS FROM COU NORTH AT 06Z. GOING FORECAST FOR FREEZING LINE AT THE SURFACE IS ALSO STRONGLY SUPPORTED BY LATEST HI-RES GUIDANCE. WHILE ITS CERTAINLY POSSIBLE THAT SOME MINOR TWEEKS WILL BE REQUIRED ONCE RAIN AND SURFACE TEMP TRENDS BECOME A BIT MORE OBVIOUS DONT THINK I CAN IMPROVE UPON ANY OF THESE AT THIS TIME. GOING ADVISORY CERTAINLY DOES A NICE JOB OF HIGHLIGHTING GREATEST FREEZING RAIN THREAT IN OUR CWA. TRUETT && .SHORT TERM... ISSUED AT 330 PM CST SAT JAN 26 2013 (TONIGHT AND SUNDAY) MAIN ITEM OF INTEREST FOR THE NEXT 24 HOURS IS THE POTENTIAL FOR FREEZING RAIN AND ICE ACCUMULATIONS. THE PATTERN WILL BE PROGRESSIVE DURING THIS PERIOD AS AN UPPER TROF DIGS ALONG THE WEST COAST KICKING THE SOUTHWEST UPPER TROF NEWD INTO THE PLAINS TONIGHT AND THEN INTO THE UPPER MS VALLEY ON SUNDAY. IN THE PROCESS THE UPPER RIDGE CURRENTLY CENTERED THRU THE WRN PLAINS WILL SHIFT TO A POSITION INVOF THE MS RIVER BY 12Z SUNDAY AND THEN INTO THE OH VALLEY BY SUNDAY EVENING. IN THE PROCESS...THE SURFACE HIGH NOW CENTERED THRU IL WILL RETREAT EWD WITH A SWLY LLJ AND LOW LEVEL WAA COMMENCING IN ITS WAKE. THIS VEERING LOW LEVEL JET IS FORECAST TO TRANSPORT WARM MOIST AIR BACK INTO THE AREA OVERNIGHT INTO SUNDAY MORNING AND PROVIDE ASCENT FOR A PRECIPITATION EVENT. A FAIRLY EXTENSIVE SHIELD OF PRECIPITATION IS EXPECTED TO DEVELOP OVERNIGHT IN RESPONSE. THE MODELS ARE IN GENERAL AGREEMENT ON THE SCENARIO BUT IN ARE TRENDING A BIT SLOWER WITH THE ONSET OF RAIN. GIVEN THE UPPER RIDGE AXIS ALONG THE MS RIVER AT DAYBREAK SUNDAY...THE THREAT OF RAIN SHOULD REMAIN TO THE WEST OF THE MS RIVER TONIGHT...SPREADING EAST ON SUNDAY MORNING WITH PROGRESSION OF THE PATTERN. THERE WILL BE A BATTLE DURING THE EVENT BETWEEN THE ARRIVAL OF WARM/ABOVE FREEZING AIR AND THE ONSET AND SPREAD OF RAINFALL. COMPLICATING THIS IS THE LOWER SURFACE DEW POINTS WILL RESULT IN EVAPORATIVE COOLING WHICH MAY INITIALLY OFFSET THE WARMING...HOWEVER GIVEN THE STRENGTH OF WARMING...THE WARM AIR WILL OVERWHELM THE RESIDUAL COLD AIR ON THE BACKSIDE OF THE RETREATING HIGH ACROSS ERN MO AND WEST CENTRAL IL. TEMPS IN MID MO MAY BE ABOVE FREEZING BY THE TIME THE RAIN BEGINS LATE TONIGHT AND IN THE ST LOUIS AREA THEY WILL BE FLIRTING WITH THE FREEZING MARK FOR SEVERAL HOURS NEAR THE ONSET. THE COLD AIR WILL BE STRONGER AND REMAIN ENTRENCHED LONGER IN NE MO AND WEST CENTRAL IL WHERE ICE ACCUMULATIONS WILL AVERAGE .10 TO .15 INCHES. I HAVE EXPANDED THE FREEZING RAIN A BIT FURTHER SOUTH WHERE THERE COULD BE SOME DECENT GLAZING. BY EARLY AFTERNOON WARM AIR WILL COMPLETELY OVERSPREAD THE REGION WITH TEMPS SOARING. GLASS && .LONG TERM... ISSUED AT 330 PM CST SAT JAN 26 2013 (SUNDAY NIGHT THROUGH TUESDAY NIGHT) THE WARM SECTOR WILL COMPLETELY OVERSPREAD THE AREA SUNDAY NIGHT AS SOUTHERLY LOW LEVEL FLOW TRANSPORTS WARM AIR AND MOISTURE NEWD. THIS WILL RESULT IN A PERIOD OF WELL ABOVE NORMAL TEMPERATURES THROUGH TUESDAY AND MOST LIKELY SOME RECORDS WILL BE SET. THE SWLY FLOW ALOFT IS LARGELY VOID OF ANY WELL-DEFINED DISTURBANCES TO CONTRIBUTE TO LARGE SCALE ASCENT THROUGH MONDAY NIGHT. THUS ANY PRECIPITATION THREAT WILL INITIALLY BE LIGHT RAIN/DRIZZLE ON SUNDAY NIGHT WITH THE MOISTURE RETURN AND THEN SCATTERED SHOWERS OR THUNDERSTORMS WITH THE SWLY LLJ AXIS. PROGRESSION OF THE WRN U.S. LARGE SCALE POSITIVELY TILTED UPPER TROF INTO THE CENTRAL CONUS AND THE PASSAGE OF THE ASSOCIATED SURFACE COLD FRONT ON TUESDAY AND TUESDAY NIGHT SHOULD LEAD TO THE WIDESPREAD SHOWERS AND THUNDERSTORMS. SEVERE POTENTIAL WILL ULTIMATELY DEPEND ON THE AMOUNT OF INSTABILITY AS DEEP LAYER SHEAR WILL BE PLENTY STRONG TO SUPPORT ORGANIZED CONVECTION. (WEDNESDAY THROUGH SATURDAY) A DEEP LONGWAVE TROF WILL EVOLVE THRU THE ERN HALF OF THE CONUS DURING THIS PERIOD. THE COLD FRONT ON TUESDAY/TUESDAY NIGHT WILL BRING AN INITIAL SURGE OF COLD AIR...WITH A BIG PUSH OF ARCTIC AIR ON THURSDAY. FRIDAY APPEARS TO BE THE COLDEST DAY WITH WELL BELOW NORMAL TEMPERATURES...THEN THE ARCTIC RETREATS BY THE WEEKEND WITH WAA UNDERWAY AND WARMING TEMPS. GLASS && .AVIATION... ISSUED AT 612 PM CST SAT JAN 26 2013 HIGH CLOUDS TO PERSIST OVER TAF SITES AHEAD OF NEXT WEATHER SYSTEM. IN THE MEANTIME...TIMING OF PCPN IS STILL HARD TO PIN DOWN ...BUT EXPECT RAIN TO BEGIN MOVING INTO CENTRAL MO BY 11Z SUNDAY...THEN SPREAD EAST OVER THE NEXT SEVERAL HOURS...REACHING THE METRO AREA AND KUIN BY 13Z. TEMPS OVER CENTRAL MO TO REMAIN ABOVE FREEZING SO KCOU TO STAY ALL RAIN. FUTHER TO THE EAST...THE METRO AREA WILL START OFF JUST BELOW FREEZING WHEN THE RAIN MOVES IN...SO HAVE A FEW HOURS OF LIGHT FREEZING RAIN...BEFORE TEMPS WARM UP ABOVE FREEZING BY 16Z SUN. ANY ICE ACCUMULATION HERE WILL BE LIGHT. AS FOR KUIN...THEY WILL SEE THE LONGEST PERIOD OF FREEZING RAIN...THROUGH ABOUT 18Z BEFORE CHANGING OVER TO ALL RAIN. WITH ONSET OF PCPN...EXPECT CIGS TO DIP DOWN TO MVFR AND REMAIN THAT WAY THROUGH END OF FORECAST PERIOD...EVEN THOUGH RAIN SHOULD MOVE OUT OF KCOU BY 16Z SUN...METRO AREA BY 19Z SUN AND KUIN BY 22Z SUN. AS FOR THE WINDS...EAST TO SOUTHEAST WINDS TO PERSIST NORTH OF WARM FRONTAL BOUNDARY...THEN SWITCH TO THE SOUTH AS WARM FRONT LIFTS NORTH. WINDS TO PICKUP SOUTH OF WARM FRONT...TO NEAR 15 KTS AT TIMES THROUGH END OF FORECAST PERIOD. SPECIFICS FOR KSTL...HIGH CLOUDS TO PERSIST OVER METRO AREA AHEAD OF NEXT WEATHER SYSTEM. IN THE MEANTIME...TIMING OF PCPN IS STILL HARD TO PIN DOWN...BUT EXPECT RAIN TO REACH THE METRO AREA BY 13Z SUN. THE METRO AREA WILL START OFF JUST BELOW FREEZING WHEN THE RAIN MOVES IN...SO HAVE A FEW HOURS OF LIGHT FREEZING RAIN...BEFORE TEMPS WARM UP ABOVE FREEZING BY 16Z SUN. ANY ICE ACCUMULATION HERE WILL BE LIGHT. WITH ONSET OF PCPN...EXPECT CIGS TO DIP DOWN TO MVFR AND REMAIN THAT WAY THROUGH END OF FORECAST PERIOD...EVEN THOUGH RAIN SHOULD MOVE OUT OF METRO AREA BY 19Z SUN. AS FOR THE WINDS...EAST TO SOUTHEAST WINDS TO PERSIST NORTH OF WARM FRONTAL BOUNDARY...THEN SWITCH TO THE SOUTH AS WARM FRONT LIFTS NORTH BY 19Z SUN. WINDS TO PICKUP SOUTH OF WARM FRONT...TO NEAR 15 KTS AT TIMES THROUGH END OF FORECAST PERIOD. BYRD && .CLIMATE... ISSUED AT 334 PM CST THU JAN 24 2013 RECORD OR NEAR RECORD-BREAKING TEMPERATURES MAY BE POSSIBLE ON MONDAY AND TUESDAY. BELOW IS A TABLE OF RECORD HIGHS AND RECORD HIGH MINIMUMS FOR ARE THREE OFFICIAL CLIMATE STATIONS: ST. LOUIS (STL)...COLUMBIA (COU)...AND QUINCY (UIN): ST. LOUIS HIGH HIGH MINIMUM 1/2876 (1970)53 (1914) 1/2973 (2008)44 (1947) COLUMBIA HIGH HIGH MINIMUM 1/28 67 (2002) 53 (1914) 1/29 64 (2008) 44 (1938) QUINCY HIGH HIGH MINIMUM 1/28 63 (1914) 46 (1914) 1/29 63 (1914) 38 (1989) && .LSX WATCHES/WARNINGS/ADVISORIES... MO...FREEZING RAIN ADVISORY FROM 4 AM TO 9 AM CST SUNDAY FOR KNOX MO- MONROE MO-SHELBY MO. FREEZING RAIN ADVISORY FROM 6 AM TO NOON CST SUNDAY FOR LEWIS MO- LINCOLN MO-MARION MO-PIKE MO-RALLS MO. IL...FREEZING RAIN ADVISORY FROM 6 AM TO NOON CST SUNDAY FOR ADAMS IL- BROWN IL-CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL- MONTGOMERY IL-PIKE IL. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1204 AM CST FRI JAN 25 2013 .SHORT TERM... ISSUED AT 334 PM CST THU JAN 24 2013 (TONIGHT) THE MAIN ISSUE FOR TONIGHT IS WHETHER OR NOT WE WILL SEE SOME LIGHT WINTRY PRECIPITATION. THE OVERALL SYNOPTIC SCENARIO APPEARS UNCHANGED. AN EXPANSIVE COLD HIGH PRESSURE SYSTEM CURRENTLY CENTERED THRU THE WRN GREAT LAKES WILL RETREAT EASTWARD THRU THE OH VALLEY AND INTO THE EASTERN U.S. BY DAYBREAK FRIDAY. IN THE PROCESS...LOW LEVEL FLOW WILL VEER TO MORE SELY TONIGHT AND A BROAD LOW LEVEL WAA REGIME WILL DEVELOP. CONCURRENTLY A VERY WEAK IMPULSE WILL TRACK THRU THE MID MS VALLEY WITHIN THE NW FLOW ALOFT. BOTH OF THESE FEATURES WILL PRODUCE SOME WEAK ASCENT WITH THE LOW LEVEL WAA MORE FOCUSED ACROSS SRN MO AND SRN IL WHILE THE MAIN ASCENT WITH THE UPPER DISTURBANCE WILL BE FOCUSED NORTH OF THE CWA. MOISTURE IS ALSO AN ISSUE WITH HIGH LEVEL MOISTURE WITHIN THE NW FLOW ALOFT STREAMING ACROSS THE AREA WHILE THE SWLY LLJ TRANSPORTS MODEST LOW LEVEL MOISTURE FROM THE SRN PLAINS AND LOWER MS VALLEY. THE RESULTANT MOISTURE STRATIFICATION IS HIGH AND LOW WITH MOST OF THE LIFT INDICATED TO BE IN BETWEEN THE TWO MOISTURE SOURCES WHERE THE AIR MASS IS DRY. NORMALLY THIS MIGHT SUGGEST DRIZZLY PCPN BUT THE LOW LEVELS WONT BE THAT DRAMATICALLY MOIST - I.E. IFR AND LOWER CIGS. THIS IS IN PART DUE TO THE DRY BOUNDARY LAYER CURRENTLY OVER THE AREA. THE GFS SEEMS TO RECOGNIZE THIS AS DOES THE HRRR AND RUC...WHICH HAVE NO QPF OR A COUPLE OF SPITS. ALTERNATIVELY THE NAM AND LOCAL WRF SUGGEST VERY LIGHT QPF OVER THE ENTIRE CWA...HOWEVER THEY ARE ALREADY IN ERROR AS THERE SHOULD BE PCPN ACROSS OK AND AR. ADDING TO THE QUANDARY IS THE THERMAL PROFILES WHICH SUGGEST SLEET OR FREEZING RAIN ACROSS SE MO AND MAINLY SNOW OR SLEET CENTERED ALONG I-70 AND SNOW FURTHER NORTH. THE BOTTOM LINE IS THAT I THINK DRIZZLE IS LESS LIKELY AND ANY PCPN THAT OCCURS WILL BE EITHER BE VERY LIGHT OR SHOWERY IN NATURE...WITH THE GREATEST PROBABILITY ACROSS SE MO AFTER 06Z. WHATEVER DOES FALL AND ACCUMULATE WILL BE VERY LIGHT. GIVEN THE UNCERTAINTIES I HAVE KEPT WITH THE CHANCE POPS FROM THE PREVIOUS FORECAST AND DONT HAVE ANY HEADLINES. THAT SAID...SOME ZL-- OR ZR-- COULD PRODUCE A VERY LIGHT GLAZE ON ANY UNTREATED SURFACES. I WILL ISSUE AN SPS TO HIGHLIGHT THIS POTENTIAL. GLASS && .LONG TERM... ISSUED AT 334 PM CST THU JAN 24 2013 (FRIDAY - SUNDAY) LIGHT PRECIPITATION SHOULD BE ON THE WAY OUT EARLY TOMORROW MORNING AS BY 1200 UTC NAM 290-305K ISENTROPIC SURFACES DEPICT SUBSIDENCE WEST OF THE MISSISSIPPI RIVER WHICH SPREADS EAST WITH TIME. LEFT SCHC POPS FOR THE EASTERN THIRD OF THE CWA WHERE WEAK MOIST/WARM ADVECTION CONTINUES UNTIL ROUGHLY 1500 UTC. SKIES SHOULD QUICKLY CLEAR OUT TOMORROW WITH SUBSIDENCE IN THE WAKE OF SHORTWAVE TROUGH PASSING THROUGH THE GREAT LAKES REGION. AT THE SFC...A WEAK COLD FRONT/WIND SHIFT WILL COME THROUGH ATTENDANT TO A SFC CYCLONE ASSOCIATED WITH THE NORTHERN STREAM CLIPPER. WITH CLEARING SKIES AND A WESTERLY COMPONENT TO THE WIND...WENT ABOVE WARMEST GUIDANCE YIELDING HIGHS FROM UPPER 30S IN THE NORTH TO NEAR 50 OVER PORTIONS OF SOUTHEAST MISSOURI. ANOTHER SHOT OF COLD CANADIAN AIR IS IN STORE FOR FRIDAY NIGHT AND SATURDAY WITH A 1030+ HPA SFC HIGH SLIDING SE INTO THE MID-MISSOURI RIVER VALLEY BY 0600 UTC SATURDAY. EXPECT LOWS IN THE TEENS AND TWENTIES WITH CLEAR SKIES AND LOW DEWPOINTS. WINDS SHOULD STAY UP JUST ENOUGH MOST LIKELY TO PREVENT DECOUPLING AND TEMPERATURES BOTTOMING OUT SEVERAL DEGREES COOLER. FOR HIGHS ON SATURDAY...COOLEST READINGS WILL BE IN THE M/U 20S OVER WEST-CENTRAL ILLINOIS AND MID 30S OVER CENTRAL MISSOURI. THESE READINGS ARE CLOSER TO COOLER MET GUIDANCE GIVEN WEAK CAA AND INCREASING CIRRUS THROUGHOUT THE DAY. CLOUDS SHOULD CONTINUE TO BE ON THE INCREASE AND GRADUALLY LOWER THROUGH SATURDAY NIGHT AS A SHORTWAVE TROUGH EJECTS OUT OF THE DESERT SOUTHWEST. THE COMBINATION OF STRONG MOIST/WARM ADVECTION AROUND THE WESTERN PERIPHERY OF A LOW-LEVEL ANTICYCLONE OVER THE GULF COAST AND DCPVA AHEAD OF THE TROUGH AXIS SHOULD PROVIDE PLENTY OF SUPPORT FOR GOING POPS. WITH COLD AIR STILL IN PLACE BEHIND DEPARTING CANADIAN AIRMASS AND COLD GROUND TEMPERATURES FROM PREVIOUS SPELLS OF ARCTIC AIR...POTENTIAL FOR ACCUMULATING FREEZING RAIN APPEARS LIKELY FOR PORTIONS OF THE AREA. CURRENT EXPECTATION IS FOR FREEZING RAIN TO BEGIN LATE SATURDAY NIGHT OVER CENTRAL MISSOURI AND SPREADING E/NE WITH TIME. ONSET OF PRECIPITATION WILL LIKELY BE A COMBINATION OF SLEET/SNOW DUE TO VERY DRY AMS BELOW 700 HPA LEADING TO STRONG EVAPORATIONAL COOLING/WET BULBING. HOWEVER...WAA WILL WIN OUT FAIRLY QUICKLY (WITHIN AN HOUR OR TWO) AND CHANGE PTYPE OVER TO FREEZING RAIN AND EVENTUALLY RAIN AS SFC TEMPS WARM ABOVE FREEZING. EXCEPTION WOULD BE OVER NORTHERN SECTIONS OF THE AREA INCLUDING QUINCY WHERE SLEET/SNOW MIX MAY CONTINUE FOR A FEW HOURS BEFORE CHANGING OVER TO FREEZING RAIN. IN THIS AREA...HAVE HALF AN INCH OF SNOW OR LESS TO ACCOUNT FOR THIS SCENARIO. GENERALLY...EXPECTING A 6-HR PERIOD OR SO OF FROZEN PRECIPITATION WITH FREEZING RAIN BEING THE PRIMARY PTYPE BEFORE THE CHANGEOVER TO PLAIN OLD RAIN FOR MOST LOCATIONS. AMOUNTS OF FREEZING RAIN IN THE CURRENT FORECAST ARE ON THE ORDER OF A TENTH OF AN INCH OR LESS...BUT CERTAINLY ENOUGH TO CREATE TRAVEL PROBLEMS FOR THOSE VENTURING OUT SUNDAY MORNING. TEMPERATURES BEHIND THE WARM FRONT WILL CONTINUE TO RISE THROUGH THE OVERNIGHT HOURS SO WENT WITH A NON-DIURNAL TEMPERATURE TREND FOR SUNDAY NIGHT. (MONDAY - THURSDAY) VERY WARM AIR IS IN STORE FOR MONDAY-TUESDAY WITH HIGHS IN THE 50S AND 60S EACH DAY. MAIN CONCERN WITH REACHING THESE TEMPERATURES IS OBVIOUSLY CLOUDS/PRECIP CHANCES. MODELS CONTINUE TO PRINT OUT LIGHT QPF EACH DAY... BUT FORCING SEEMS INNOCUOUS AND BELIEVE MODELS ARE DOING THIS DUE TO THE VERY STRONG AND ANOMALOUS LOW-LEVEL MOISTURE RETURN. WARMEST DAY SHOULD BE TUESDAY AHEAD OF FRONT AS NWP GUIDANCE HAS 850-HPA TEMPS AOA +8C. DEEP MIXING FOR THE TIME OF YEAR TO NEAR 850 HPA AND COMPRESSIONAL WARMING AHEAD OF FRONT ALL SUGGEST HIGHS NEAR RECORD OR RECORD-BREAKING. THEREFORE... HAVE OPTED TO INCLUDE RECORD HIGHS AND RECORD HIGH MINIMUMS FOR MONDAY AND TUESDAY IN THE CLIMO SECTION BELOW. HIGH TEMPERATURES...ESPECIALLY FOR TUESDAY...WOULD LIKELY BE SEVERAL DEGREES TOO COOL IF THERE ARE BREAKS IN THE CLOUDS. FOR EARLY WEEK...WENT AT LEAST A FEW DEGREES ABOVE CR INITIALIZATION DUE TO REASONING MENTIONED ABOVE. COLD FRONT SHOULD MOVE THROUGH ON THE DAY TUESDAY WITH SHOWERS AND THUNDERSTORMS STILL A GOOD BET ALONG AND AHEAD OF THE BOUNDARY. ALSO POTENTIAL FOR SEVERE WEATHER GIVEN STRONG DYNAMICS PROGGED AND INSTABILITY PARAMETERS. SFC DEWPOINTS MAY EVEN APPROACH 60 DEGREES...WHICH FOR THIS TIME OF YEAR IS CERTAINLY A RED FLAG FOR POTENTIAL STRONG TO SEVERE STORMS. HOWEVER...THERE IS STILL QUITE A BIT OF UNCERTAINTY IN REGARDS TO EXACT TRACK OF SFC LOW AND AMOUNT OF INSTABILITY AHEAD OF BOUNDARY. NEW ECMWF WHICH CUTS OFF SHORTWAVE TROUGH OFF THE COAST OF CALIFORNIA WITH A NORTHERN STREAM SHORTWAVE TRAVERSING THE NORTHERN PLAINS IS AN OUTLIER AND WAS DISCOUNTED FOR NOW. THIS SCENARIO WOULD HAVE A WEAKER FROPA EARLIER ON TUESDAY WITH LESS DYNAMICS FOR SEVERE WEATHER. BEHIND THE COLD FRONT...WEDNESDAY AND THURSDAY LOOK MUCH COOLER...I.E.... TOWARD SEASONAL NORMS WITH HIGHS IN THE 30S AND 40S. THIS TIME PERIOD ALSO WILL LIKELY BE DRY...THOUGH SOME MODELS HAVE HINTED AT THE POSSIBILITY OF SOME ENERGY LAGGING BEHIND IN THE FOUR-CORNERS REGION WHICH COULD YIELD POTENTIALLY WINTRY WEATHER SOMETIME LATER NEXT WEEK. GOSSELIN && .AVIATION... ISSUED AT 1129 PM CST THU JAN 24 2013 MAIN FCST CHALLENGE CONTINUES TO BE THE DVLPMNT OF WINTRY PRECIP TOWARDS MRNG. THE STRONG AREA OF HIGH PRESSURE THAT PUSHED A STRONG COLD FRONT THRU YESTERDAY HAS MOVED TO THE EAST COAST ALLOWING WINDS TO TURN ESE/SE THIS EVENING. THE COLD FRONT CURRENTLY STRETCHES FROM NTHRN TX ALONG THE AR/LA BORDER ACROSS CNTRL MS AND ON INTO THE TN VLY. A WEAK AREA OF LOW PRESSURE IS FCST TO MOVE ALONG THE FRONT THRU TOMORROW AND SHOULD BE LOCATED IN THE UPPER OH RIVER VLY BY TOMORROW EVENING. THE SRLY FLOW ON THE BACKSIDE OF THE HIGH AND THE CIRCULATION IN ASSOC WITH THE LOW PRESSURE WILL ALLOW WARM AND MORE MOIST AIR TO SURGE NORTH OVER TOP THE COLD AIR AT THE SFC. THERE IS MOISTURE AND CLOUDS AOA 15 KFT AND MOISTURE AND CLOUDS AOB 8KFT. THE QUESTION IS IF THERE IS ENOUGH LIFT WHERE THE MOISTURE IS TO PRODUCE PRECIP. MODELS CONTINUE TO INDICATE TOO MUCH PRECIP...THOUGH THEY HAVE TRENDED DRIER THIS EVENING. IF ANYTHING DOES DVLP...IT SHOULD BE LIGHT AND SHORT LIVED. IF IT DVLPS...IT SHOULD BE ALL SNOW AT KUIN BUT A MIX OF FREEZING RAIN/DRIZZLE AND/OR SLEET IN THE STL METRO. PRECIP SHOULD BE EAST OF KCOU IF IT DVLPS. NOT CONFIDENT ENOUGH TO INCLUDE ANY PRECIP ATTM SO CONVERTED THE PROB30 TO VCSH TO INDICATE THE UNCERTAINTY. A COLD FRONT PUSHES THRU TOMORROW MORNING ENDING THE PRECIP THREAT AND CLOUDS WILL CLEAR FROM W-E AFTER FROPA. SPECIFICS FOR KSTL... LIGHT WINTRY MIX POSSIBLE TOWARDS SUNRISE. SHOULD BE VERY LIGHT AND BRIEF. NOT CONFIDENT ENOUGH IN THE DVLPMNT OF THE PRECIP TO INCLUDE ATTM...CONVERTED THE PROB30 GROUP TO VCSH TO TRY AND CONVEY THE UNCERTAINTY. WINDS GO WESTERLY TOMORROW MORNING AFTER A COLD FRONT AND SKIES SHOULD CLEAR BY NOON. 2% && .CLIMATE... ISSUED AT 334 PM CST THU JAN 24 2013 RECORD OR NEAR RECORD-BREAKING TEMPERATURES ARE EXPECTED ON MONDAY AND TUESDAY. BELOW IS A TABLE OF RECORD HIGHS AND RECORD HIGH MINIMUMS FOR ARE THREE OFFICIAL CLIMATE STATIONS: ST. LOUIS (STL)...COLUMBIA (COU)...AND QUINCY (UIN): ST. LOUIS HIGH HIGH MINIMUM 1/2876 (1970)53 (1914) 1/2973 (2008)44 (1947) COLUMBIA HIGH HIGH MINIMUM 1/28 67 (2002) 53 (1914) 1/29 64 (2008) 44 (1938) QUINCY HIGH HIGH MINIMUM 1/28 63 (1914) 46 (1914) 1/29 63 (1914) 38 (1989) && .PRELIMINARY POINT TEMPS/POPS... ST LOUIS 23 45 22 31 / 30 10 0 0 QUINCY 19 37 14 26 / 30 10 0 0 COLUMBIA 23 46 20 36 / 20 10 0 5 JEFFERSON CITY 25 47 19 37 / 20 10 0 5 SALEM 23 42 22 30 / 40 20 0 0 FARMINGTON 25 48 22 34 / 40 10 0 0 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
529 PM CST SAT JAN 26 2013 .AVIATION...00Z TAFS FOR KOFK...KLNK AND KOMA. VFR CONDITIONS DURING THE EVENING WILL RAPIDLY DROP TO IFR BETWEEN 08Z AND 12Z AS A LOW PRESSURE SYSTEM SPREADS RAIN INTO EASTERN NEBRASKA. EXPECT RAIN TO BEGIN IN KLNK BY 09Z THEN KOMA AND KLNK BEFORE 12Z. CIGS WILL LIKELY DROP BELOW FL010 AS THE RAIN MOVES IN...WITH VSBYS AROUND 2SM. HEAVIEST RAIN WILL MOVE OUT BY 18Z...BUT IFR/MVFR CONDITIONS SHOULD HOLD ON THROUGH THE AFTERNOON AS DRIZZLE AND FOG LINGER. ALSO...LOW LEVEL WIND SHEAR IS EXPECTED OVERNIGHT WITH SOUTHERLY LOW LEVEL JET KICKING UP TO 45KT AT FL020. DERGAN && .PREV DISCUSSION... /ISSUED 331 PM CST SAT JAN 26 2013/ SHORT TERM...TONIGHT THROUGH TUESDAY SHORT TERM FORECAST CONCERNS WILL BE THE ASSOCIATED DETAILS WITH THE PRECIPITATION EVENT TONIGHT AND SUNDAY...THEN DRIZZLE AND FOG AS LIFT DECREASES LATER SUNDAY INTO SUNDAY NIGHT. POTENTIAL FOR LIGHT PRECIPITATION MONDAY IN SOUTHEAST NEB NEAR H85 FRONT AND IN THE NORTHEAST NEB WITH A COLD FRONT AND ACROSS THE FORECAST AREA INTO TUESDAY. THE SURFACE WARM FRONT IS LIFTING NORTH AND BRISK SOUTH WINDS HAVE WARMED TEMPERATURES INTO THE 40S AND 50S...WITH BEATRICE NEARLY REACHING 60. SURFACE DEWPOINTS ARE VARIABLE IN THE TEENS AND 20S. 3HR PRESSURE FALLS WERE NOTED ACROSS MUCH OF THE PLAINS IN RESPONSE TO LOWERING PRESSURE OVER THE EASTERN ROCKIES. PER VISIBLE SATELLITE AND METARS...LOW LEVEL STRATUS IS BEGINNING TO WORK NORTH AND THIS IS THE LEADING EDGE OF THE MID 30S DEWPOINTS. WATER VAPOR SATELLITE IMAGERY AND LIGHTNING DATA...SHOWED THE SHORTWAVE TROF HAD MOVED INTO THE SOUTHWEST U.S. BY MIDDAY AND THERE WERE LIGHTNING STRIKES OVER EASTERN ARIZONA. THIS WAVE WILL BE OUR WEATHER MAKER THROUGH SUNDAY. THE H9 JET IS FROM THE SOUTH AT 25 TO 35KT AND WILL CONTINUE TO INCREASE TO 35 TO 45KT OVER THE FORECAST AREA THROUGH 06Z. MEANWHILE...THE NOSE OF THE H85 50KT JET IS OVER SOUTHWEST KS. THETA-ADVECTION AND H7 OMEGA INCREASE ACROSS KANSAS THROUGH 06Z AND THEN ACROSS NEBRASKA INTO IOWA AND MISSOURI THROUGH 12Z. THERE ALSO IS SOME UPPER LEVEL JET SUPPORT BY 12Z. THE 4KM WRF/NAM/GFS/SREF/EC/RAP ARE SIMILAR IN HAVING THE PRECIPITATION OVERSPREADING THE FORECAST AREA FROM SOUTHWEST TO NORTHEAST MAINLY BETWEEN 08Z AND 14Z. REGARDING PRECIPITATION TYPE...WILL NEED TO MONITOR AREAS IN FAR NORTHEAST NEBRASKA AND PARTS OF WESTERN IOWA SHOULD PRECIPITATION BEGIN AS FREEZING RAIN. THE MODELS ARE NOT IN GOOD AGREEMENT WITH THE LOW LEVEL TEMPS. THE NAM SEEMS QUITE COOL...AND SEVERAL OF THE OTHER MODELS ARE A BIT WARMER. TRENDED WITH THE WARMER RAP TEMPERATURES VERSUS THE COOLER NAM TEMPS. WITH THE VERY MILD CONDITIONS THIS EVENING AND INCREASING CLOUDS AND STRONG SOUTH FLOW...THINK MOST LOCATIONS WILL BE ABOVE FREEZING WHEN THE PRECIPITATION STARTS...SO LEFT FREEZING MENTION ONLY IN THE FAR NORTHEAST ZONES. AS THE SHORTWAVE MOVES EAST...SO DOES THE PRECIPITATION AND LOOK FOR DRIZZLE AND FOG LATER SUNDAY AFTERNOON AND SUNDAY NIGHT. RAINFALL AMOUNTS LOOK TO VARY FROM 0.1 TO .4 OF AN INCH. THE COLD FRONT IS NEAR FALLS CITY BY 06Z SUNDAY NIGHT...HOWEVER THE LOW LEVEL MOISTURE DOES NOT GET SCOURED OUT. WITH THE WEAK FLOW OVERNIGHT DO MENTION FOG. WILL NEED TO WATCH FOR BELOW FREEZING TEMPERATURES AND FOG FOR THE MONDAY MORNING COMMUTE...AS THIS COULD CAUSE PROBLEMS. MONDAY...THERE IS WARM AIR ADVECTION ACROSS THE SOUTHERN CWA AND MAY SEE SOME LIGHT PRECIP. IN THE NORTHWEST PART OF THE FORECAST AREA...THERE IS A REINFORCING COLD FRONT SLOWLY MOVING SOUTHEAST ASSOCIATED WITH THE MID LEVEL TROF. THIS FRONT HAS SOME DECENT FRONTOGENESIS WITH IT AND MONDAY INTO TUESDAY COULD BRING SOME RAIN...A MIX AND THEN POSSIBLE A NARROW BAND OF LIGHT SNOW. IT IS INTERESTING THAT THERE IS SOME ELEVATED INSTABILITY WITH THIS BAND AND ALSO NEAR THE H85 FRONT IN SOUTHERN NEBRASKA MONDAY NIGHT. FOR NOW...TOP/EAX HAVE SOME TSRA MENTIONED IN THEIR CWA MONDAY NIGHT AND WE HAVE RAIN IN THE SOUTH AND A RAIN/SNOW MIX THEN ALL SNOW NORTH. TEMPERATURES ARE GOING TO BE A CHALLENGE EACH DAY AND HAVE HIGHS SUNDAY AND MONDAY IN THE 30S TO AROUND 40 FAR NORTH TO THE 50S SOUTH. TUESDAY HAVE HIGHS IN THE LOWER 30S NORTH TO UPPER 40S SOUTH. ZAPOTOCNY LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. THE UPPER LEVEL FLOW PATTERN WILL TRANSITION TO THE NORTHWEST DURING THIS PERIOD AND THE GLOBAL MODELS ARE IN PRETTY GOOD AGREEMENT ON THIS EVOLUTION. THE UPPER LEVEL TROUGH FOR MON/TUE WILL JUST BE EXITING THE REGION ON TUE NIGHT AND WILL LINGER SOME SCHC POPS FOR -SN IN THE SOUTH AS THIS EXITS...OTHERWISE THE EXTENDED PART OF THE FORECAST IS DRY. AN ARCTIC COLD FRONT WILL MOVE THROUGH THE FA ON WED NIGHT WHICH WILL LEAD TO MUCH COLDER HIGHS ON THU AND LOWS THU NIGHT. BUT LIKE RECENT COLD SURGES...THIS WILL BE GREATLY MODIFIED BY THE LACK OF SNOW COVER ACROSS THE FA. THUS WE ARE EXPECTING HIGHS IN THE TEENS/20S AND LOWS IN THE SINGLE DIGITS ABOVE ZERO. THE UPPER LEVEL RIDGE TO THE WEST WILL SHIFT A BIT EAST ON ON FRI/SAT AND ALLOW FOR SOME DOWN-SLOPE AND PACIFIC AIR TO SPILL BACK INTO THE FA. NORMAL HIGHS WITH NO SNOW COVER BY THE END OF THE PERIOD ARE IN THE LOWER TO MID 40S...AND WE SEE NO REASON WE CAN`T GET NEAR THESE NUMBERS. THUS WE HAVE GONE ABOVE THE CLIMO HEAVY MOS GUIDANCE FOR THE END OF THE PERIOD. BOUSTEAD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
339 PM CST FRI JAN 25 2013 .SHORT TERM...TONIGHT THROUGH MONDAY. THE FORECAST CONCERNS IN THE SHORT TERM WILL BE TEMPERATURES BEHIND THE COLD FRONT TONIGHT...ONSET OF PRECIPITATION SATURDAY NIGHT AND SUNDAY AND PRECIPITATION TYPE...AND PRECIPITATION AND PRECIP TYPE WITH MONDAY SYSTEM. TEMPERATURES AHEAD OF A COLD FRONT HAVE WARMED INTO THE 40S AND 50S...HOWEVER MUCH COLDER AIR LIES TO THE NORTH WITH TEENS AS FAR SOUTH AS HURON SD. THIS COLD FRONT WILL PUSH THROUGH PARTS OF THE FORECAST AREA. THE RAP SEEMS TO HAVE A GOOD HANDLE ON THE COLD AIR. THE BRUNT OF THE COLD AIR AND SUB-ZERO READINGS WILL HOLD OVER IN SD AND MN...TEMPERATURES IN THE TEENS (POSSIBLY SINGLE DIGITS NEAR WAYNE AND MAPLETON) SHOULD MAKE IT INTO THE NORTHEAST HALF OF THE FORECAST AREA WITH 20S FOR THE SOUTH. SOME CIRRUS TONIGHT ALONG WITH SOME PATCHY LOW AND MID CLOUDS NORTH. SURFACE WINDS BECOME LIGHT SOUTHEAST TONIGHT AND HAVE A DECENT GRADIENT IN DEWPOINTS AND TEMPERATURES FROM MAPLETON TO THE SOUTHWEST TOWARD FAIRBURY. WITH THE STORM SYSTEM FOR THE WEEKEND STILL OFF THE CA/MEXICAN COAST...THERE COULD BE SAMPLING ISSUES AND OPENS THE FORECAST UP TO TIMING CHANGES. FOR NOW...THERE IS DECENT AGREEMENT BETWEEN THE SHORT RANGE MODELS THAT THE SHORTWAVE TROF WILL MOVE THROUGH THE SOUTHWEST U.S. SATURDAY WITH SURFACE LOW PRESSURE OVER THE WESTERN PLAINS AND A STRENGTHENING LOW LEVEL JET OVER THE PLAINS. LIFT ASSOCIATED WITH THE TROF AND WARM AIR ADVECTION BRING INCREASING CLOUDS AND SPREAD PRECIPITATION FROM THE SOUTHWEST U.S. INTO THE PLAINS. THE ONSET OF THE PRECIPITATION SHOULD MAINLY BE AFTER MIDNIGHT...ALTHOUGH COULD EASILY START IN THE EVENING TOWARD THE KANSAS/NEBRASKA BORDER...AND MOVE NORTHEAST ACROSS EASTERN NEBRASKA AND IOWA DURING THE DAY SUNDAY. THE PRECIPITATION COULD START OUT AS FREEZING RAIN WHERE TEMPERATURES ARE AT OR BELOW ZERO (MAINLY NORTH OF A NORFOLK TO TEKAMAH TO OAKLAND)...HOWEVER HAVE THE BULK OF THE PRECIPITATION STARTING OUT AS RAIN. THE BEST LIFT APPEARS FROM AROUND 10Z TO 20Z SUNDAY. THE SOUTHWEST FLOW ALOFT WILL BRING HIGH PRECIP WATER VALUES TO THE REGION... .5 INCH TO 1 INCH. FOR NOW A BEST ESTIMATE OF AMOUNTS WITH THE STORM IS LESS THAN A TENTH OF AN INCH OF WATER AT NORFOLK NORTHWESTWARD...A QUARTER OF AN INCH OR SO OMAHA TO LINCOLN AND A HALF AN INCH TOWARD FALLS CITY. HIGHS SATURDAY AND SUNDAY SHOULD BE IN THE 30S AND 40S. A FEW LOCATIONS MAY HIT THE 50S SOUTH. THE MAIN MID LEVEL TROF IS STILL TO THE WEST AND THE LOW LEVEL MOISTURE DOES NOT GET SCOURED OUT. WITH THE WEAK FLOW DO HAVE SOME FOG MENTIONED AND WILL HAVE TO WATCH FOR FREEZING FOG CONDITIONS. A STRONGER PUSH OF COLD AIR OCCURS MONDAY. MAY SEE SOME LIGHT RAIN OR DRIZZLE FOR PARTS OF THE AREA MONDAY AND BEHIND THE H85 COLD FRONT A BAND OF SNOW MAY DEVELOP IN NORTHEAST NEBRASKA. ZAPOTOCNY && .LONG TERM...MONDAY NIGHT THROUGH FRIDAY. THE MAIN STORY IN THE EXTENDED IS STILL THE LARGE-SCALE TROUGH TO MOVE THROUGH THE AREA TUESDAY AND THEN SOME SEASONABLY CHILLY AIR FOR THE REST OF THE PERIOD. THE GLOBAL MODELS ARE STILL SHOWING SIGNIFICANT RUN TO RUN FLUCTUATION IN REGARDS TO THE TROUGH AS IT CROSSES THE CENTRAL CONUS. THE 12Z ECMWF HAS TRENDED TOWARD A MORE CONSISTENT GFS/GEM WITH REGARDS TO THE INTERACTION OF THE NRN AND SRN STREAM SHORTWAVE IN THE LARGER MEAN TROUGH BUT STILL THE MODELS DIFFER ON THE SENSIBLE WEATHER THAT WILL MOVE THE CWA. THERE IS A GOOD DEAL OF CONFIDENCE THAT A CDFNT WILL MOVE THROUGH THE FA ON MON NIGHT AS LOW PRESSURE MOVES THROUGH KS/MO AND STARTS TO DEEPEN OVER THE GREAT LAKES. MID LEVEL FRONTOGENESIS BEHIND THE FNT COULD LEAD TO A LITTLE -RA/SN MIX ON MON NIGHT INTO TUE MORNING AS THIS SYSTEM MOVES THROUGH...BUT THE THREAT FOR WIDESPREAD OR SIGNIFICANT PRECIP LOOKS VERY LOW ATTM. WE WILL MAINTAIN SOME CHC/SCHC POPS FOR THESE TWO PERIODS. OTHERWISE SURFACE HIGH PRESSURE WILL BUILD SOUTH INTO THE CENTRAL AND NORTHERN PLAINS FOR TUE NIGHT THRU FRI WITH DRY WEATHER THESE PERIODS. THE DEGREE OF COLD AIR WILL LIKELY ONCE AGAIN BE MODIFIED BY THE LACK OF SNOW COVER ACROSS THE REGION...BUT OVERALL BELOW NORMAL TEMPERATURES APPEAR LIKELY. BOUSTEAD $ .AVIATION... 12Z TAFS FOR KOMA...KLNK...KOFK. VFR CONDITIONS WILL PREVAIL THRU THE FCST PD. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1131 PM CST THU JAN 24 2013 .AVIATION...06Z KGRI TAF. CONFIDENCE IS HIGH THAT THIS WILL BE A BENIGN 24 HOURS AVIATION-WISE...WITH UNRESTRICTED VISIBILITY AND ONLY LIMITED COVERAGE OF MID-HIGH CLOUDS NEAR/ABOVE 10 THOUSAND FEET. SURFACE WINDS SPEEDS WILL LARGELY REMAIN BELOW 9KT...AS DIRECTION SHIFTS FROM WESTERLY TONIGHT...TO VARIABLE FRIDAY AFTERNOON...TO SOUTHERLY FRIDAY EVENING. THE ONLY POSSIBLE ISSUE OF NOTE IS A BRIEF PERIOD OF BORDERLINE LOW LEVEL WIND SHEAR MAINLY BETWEEN 09Z-12Z EARLY THIS MORNING...AS NORTHERLY WINDS BETWEEN 1 AND 2 THOUSAND FEET AGL ACCELERATE TO BETWEEN 33-37KT. HOWEVER...THE OVERALL BULK SHEAR MAGNITUDE DIFFERENCE BETWEEN THE SURFACE AND THIS LEVEL SHOULD BARELY REACH/EXCEED 30 KNOTS...SO WILL CONTINUE TO CONSIDER THIS A BIT MARGINAL FOR FORMAL INCLUSION IN THE TAF. && .PREV DISCUSSION... /ISSUED 254 PM CST THU JAN 24 2013/ SHORT TERM...TONIGHT THROUGH FRIDAY AFTERNOON...PLENTY OF CLOUD COVER ACROSS THE REGION THIS AFTERNOON AS A WARM FRONT ACROSS WESTERN NEBRASKA IS SLOWLY PROGRESSING EASTWARD. THIS THICK CLOUD COVER HAS LIMITED SOLAR HEATING TODAY...AND WITH A COLD AIRMASS IN PLACE...HAVE STRUGGLED TO CLIMB OUT OF THE TEENS SO FAR IN SPOTS...WHILE IN WESTERN NEBRASKA BEHIND THE WARM FRONT... TEMPERATURES MANAGED TO CLIMB INTO THE LOWER 60S. AS THIS WARM FRONT CROSS THE LOCAL AREA DURING THE EVENING HOURS...EXPECT LOW TEMPERATURES TO BE REALIZED JUST AHEAD OF THE BOUNDARY PASSAGE...WITH STEADY OR SLOWLY RISING TEMPERATURES POSSIBLE OVERNIGHT. WITH HRRR AND NAM IN FAIR AGREEMENT...TAKING THIS FRONT ACROSS KGRI AROUND 3Z...WENT AHEAD AND ADJUSTED HOURLY TEMPERATURE GRIDS TO REFLECT LOW TEMPERATURES AT MOST AREAS BETWEEN 00Z AND 04Z THIS EVENING. OTHER THAN THE WARMER AIRMASS AND SWITCH TO MORE SOUTHWESTERLY WINDS WITH THE PASSAGE OF THIS FRONT...NO OTHER IMPACTS ARE EXPECTED. FOR FRIDAY...EXPECT THE WARMER AIRMASS IN PLACE ACROSS THE LOCAL AREA COMBINED WITH LIGHT WEST NORTHWESTERLY DOWNSLOPE FLOW...TO HELP AFTERNOON TEMPERATURES SOAR PAST SEASONAL NORMALS...WITH MID TO UPPER 40S FORECAST FOR MOST LOCATIONS. A PASSING SHORTWAVE OVER THE TOP OF THE RIDGE IS EXPECTED TO REMAIN WELL TO THE NORTH OF THE LOCAL AREA...WITH THE ASSOCIATED SURFACE COLD FRONT NOT EXPECTED TO REACH THE LOCAL AREA. THEREFORE...WITH THINNING CLOUD COVER BEHIND THE WARM FRONT AND LIGHT NORTHWESTERLY SURFACE WINDS...A MOSTLY SUNNY AND PLEASANT END TO THE WEEK IS EXPECTED ACROSS THE REGION. LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS WILL BE CHANCE FOR PRECIPITATION SATURDAY NIGHT INTO SUNDAY AND AGAIN MONDAY NIGHT INTO TUESDAY AND TEMPERATURES THROUGH THE PERIOD. A BROAD UPPER LEVEL RIDGE WILL DRIFT THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. TEMPERATURES FRIDAY NIGHT WILL STILL DROP INTO THE TEENS AND LOWER 20S. DURING THE DAY WINDS WILL TURN TO THE SOUTH AND WITH WARM ADVECTION THE TEMPERATURES SHOULD RISE INTO THE 40S TO LOWER 50S. BY SATURDAY NIGHT THERE IS AN UPPER LEVEL WAVE THAT MOVES INTO THE AREA. THE SOUTH WINDS DURING THE DAY ON SATURDAY WILL BRING MOIST AIR INTO THE AREA. BY SATURDAY NIGHT THERE ARE SOME DIFFERENCES IN THE LOCATION OF THE PRECIPITATION DURING THE NIGHT. THE GFS BRINGS MORE PRECIPITATION INTO THE AREA WHERE THE ECMWF AND THE NAM KEEP THE PRECIPITATION FURTHER TO THE SOUTH. HAVE LOWERED THE CHANCES FOR PRECIPITATION FOR THE NORTH AND WEST A BIT. THE QUESTION BECOMES WHAT TYPE OF PRECIPITATION TO EXPECT. MOST OF THE NIGHT THERE WILL BE RAIN AS THE TEMPERATURES WILL BE WARM ENOUGH FOR PRECIPITATION TO REMAIN LIQUID. THE PROBLEM BECOMES TOWARD MORNING AS PRECIPITATION SPREADS FURTHER TO THE NORTH. THERE COULD BE A BRIEF PERIOD OF SOME FREEZING RAIN FURTHER NORTH. BY SUNDAY MORNING THE TEMPERATURES SHOULD WARM UP AND PRECIPITATION SHOULD TURN TO RAIN ACROSS THE AREA. BY LATER IN THE DAY ON SUNDAY THE RAIN SHOULD START TO MOVE OUT OF THE AREA. SUNDAY NIGHT AND MONDAY THERE WILL BE A DEVELOPING WAVE IN THE WESTERN CONUS AND SOUTHWEST FLOW ACROSS THE AREA. THERE WILL BE WARM ADVECTION AND MILD TEMPERATURES. BY MONDAY NIGHT THE UPPER LEVEL WAVE STARTS TO AFFECT THE FORECAST AREA. MODELS HAVE SOME DIFFERENCES IN THE PROGRESSION OF THE WAVE ACROSS THE AREA. THE GFS IS FASTER WITH A MORE OPEN WAVE WHILE THE ECMWF IS SLOWER WITH A CLOSED LOW. HAVE KEPT THE PRECIPITATION IN ACROSS THE AREA FOR MONDAY NIGHT INTO TUESDAY WHICH IS CLOSER TO THE GFS. THERE IS COLDER AIR MOVING INTO THE AREA BEHIND A COLD FRONT THAT MOVES THROUGH MONDAY NIGHT. EXPECT RAIN OR SNOW MONDAY NIGHT WITH THE COLDER AIR MOVING INTO THE AREA. THEN ON TUESDAY THERE WILL BE SNOW FURTHER WEST OR NORTHWEST WHERE THE COLDER AIR IS...RAIN IN THE SOUTHEAST AND A MIX OF RAIN OR SNOW POSSIBLE IN BETWEEN. COLD AIR CONTINUES ACROSS THE AREA ON WEDNESDAY BUT THERE IS A LITTLE WARM ADVECTION AND TEMPERATURES WARM A LITTLE FOR THURSDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
930 PM EST SAT JAN 26 2013 .SYNOPSIS... COLD AND DRY HIGH PRESSURE WILL HOLD OVER THE AREA THROUGH SUNDAY. AN UPPER LEVEL DISTURBANCE WILL PASS NORTHEASTWARD THROUGH THE REGION SUNDAY NIGHT THROUGH MONDAY MORNING. THE SURFACE HIGH WILL MOVE OFF THE COAST LATE MONDAY... FOLLOWED BY A WARM SOUTHWEST FLOW INTO THE REGION THROUGH MIDWEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 925 PM SATURDAY... THROUGH TONIGHT: INTERESTING FORECAST TONIGHT AS PATCHES OF FOG HAVE DEVELOPED OVER THE STATE... WHILE TWO AREAS OF STRATUS -- ONE JUST SW OF RALEIGH AND A LARGER ONE OVER THE INTERIOR CENTRAL/NRN COASTAL AREA -- SLOWLY DRIFT TOWARD THE WEST WITHIN THE PREVAILING LIGHT NEAR-SURFACE FLOW FROM THE ENE. THIS AFTERNOON`S LARGE-SCALE COMPUTER MODELS DID NOT PICK UP ON THIS WELL AT ALL... BUT THE RAPID-UPDATE FINE-SCALE MODELS SUCH AS THE HRRR ARE DEPICTING IT FAIRLY WELL... SHOWING THE STRATUS OVER EASTERN NC CONTINUING TO DRIFT WESTWARD THROUGH CENTRAL NC OVERNIGHT. THE NEW 12KM NAM RUN SHOWS THE NEXT POINT OF CONCERN -- THE BATCH OF HIGHER-BASED CLOUDS OVER EAST-CENTRAL VA -- ADVECTING SOUTHWARD OVERNIGHT AS THE SURFACE HIGH -- LOCATED OVER NORTH CENTRAL OH AT 00Z -- DRIFT EASTWARD TONIGHT AND NOSING MORE STRONGLY TO THE SSE INTO NC. WE`RE ALREADY SEEING SOME LOWER SURFACE DEW POINTS STARTING TO WORK SOUTHWARD FROM VA TOWARD NC... WHICH SHOULD LIMIT THE LIFETIME AND EXTEND OF FOG THROUGH THE NIGHT... BUT NEVERTHELESS A FEW SPOTS WILL SEE VSBYS UNDER A MILE FOR A COUPLE OF HOURS... EXACERBATED IN SPOTS BY THE LINGERING MOIST GROUND AND REMAINING PATCHY SNOW/ICE/SLEET ACCUMULATIONS... WITH GENERALLY LIGHT WINDS. HAVE ADDED THIS FOG TO THE FORECAST... AS WELL AS BEEFING UP THE CLOUD COVER ESPECIALLY IN THE EASTERN AND NORTHERN CWA. THE RISK OF BLACK ICE REMAINS TONIGHT INTO SUNDAY MORNING AS TEMPS WILL BOTTOM OUT BELOW FREEZING TOWARD MORNING. DESPITE SLIPPING DEW POINTS LATE TONIGHT... WITH CLOUDS IN PLAY... HAVE NUDGED LOWS UPWARD SLIGHTLY TO 23-28. -GIH SUNDAY...S/W RIDGE DRIFTS EWD ACROSS THE LOWER OH AND TN VALLEYS. THIS FEATURE WILL MAINTAIN A SURFACE RIDGE ACROSS THE CAROLINAS. THE AIR MASS ASSOCIATED WITH THE SURFACE RIDGE WILL SLOWLY MODIFY. THUS...SHOULD SEE AFTERNOON TEMPS ABOUT 3-4 DEGREES WARMER THAN CURRENT AFTERNOON TEMPS. MAX TEMPS SUNDAY IN THE LOW-MID 40S. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 305 PM SATURDAY... SUNDAY NIGHT...SURFACE RIDGE AXIS SLIDES SE...PLACING CENTRAL NC IN THE RETURN FLOW SIDE OF THE HIGH...INITIATING A LOW LEVEL WARM AIR ADVECTION REGIME. W-SW FLOW ALOFT WILL ADVECT MOISTURE INTO THE REGION...AHEAD OF AN UPPER LEVEL LOW PRESSURE SYSTEM THAT WILL SKIRT WELL W-NW OF OUR REGION. THUS ANTICIPATE INCREASING CLOUDINESS SUNDAY NIGHT. MODEL GUIDANCE CONTINUES TO PAINT PATCHY PRECIP ACROSS MAINLY THE NW AND FAR NORTHERN SECTION OF THE CWA OVERNIGHT SUNDAY NIGHT THROUGH MID MORNING MONDAY. MODEL LIFT RATHER ANEMIC THOUGH...MAINLY CENTERED ALOFT. ATMOSPHERE BELOW WHILE AIR MASS ABOVE 4000FT WILL UNDERGO DECENT WARMING...AIR MASS NEAR THE SURFACE WILL STILL RETAIN SOME OF ITS RESIDUAL COOL DRY AIR. SURFACE WET BULB TEMPS REMAIN BELOW FREEZING THROUGH 12Z MONDAY. THUS...WHAT PRECIP FALLS THROUGH THE COLUMN WILL LEAD TO SOME COOLING OF THE TEMP PROFILE NEAR THE SURFACE. MODEL TEMP PROFILE AND PARTIAL THICKNESSES SUGGEST MAIN P-TYPE FZRA AND/OR RAIN. EVEN IF FZRA/FZDZ WERE TO OCCUR...IT WILL BE SPOTTY AND VERY LIGHT IN NATURE DUE TO LACK OF ORGANIZED LIFT IN THE LOW-MID LEVELS. THUS NOT ANTICIPATING WIDESPREAD TRAVEL ISSUES EARLY MONDAY MORNING BUT CANNOT RULE OUT THE POTENTIAL FOR A SLICK BRIDGE OR TWO. IF/WHEN IT BECOMES MORE CERTAIN PATCHY FZRA/FZDZ WILL OCCUR...A WINTER WEATHER ADVISORY MAY BE NECESSARY. MIN TEMPS NEAR 30 TO THE LOWER 30S. -WSS MONDAY AND MONDAY NIGHT: THE CENTER OF ANOTHER ARCTIC HIGH...1030 MB CENTERED NEAR CHICAGO AT 19Z/26TH...WILL HAVE MODIFIED AND DRIFTED OFF THE NC COAST BY MONDAY...THOUGH THE LINGERING IN-SITU CAD EFFECTS WILL REMAIN. AFTER THE EARLY MORNING PRECIPITATION REFERENCED ABOVE...THIS IN-SITU WEDGE WILL MAINTAIN A LOW OVERCAST...WITH TEMPERATURES AOB WHAT NWP WOULD SUGGEST. WHILE SOME PARTIAL CLEARING WILL BE POSSIBLE LATE IN THE DAY OVER THE SANDHILLS...LOW STRATUS AND FOG - SOME DENSE - WILL ENVELOP CENTRAL NC SHORTLY AFTER NIGHTFALL. HIGHS 45 TO 55...WITH A MINIMAL DIURNAL FALL INTO THE 39 TO 46 DEGREE RANGE OVERNIGHT. -MWS && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 245 PM SATURDAY... A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION FROM A PAIR OF RIDGES ALONG EACH COAST...WITH A HIGHLY AMPLIFIED BUT PROGRESSIVE TROUGH IN BETWEEN. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM...THROUGH THE EASTERN US/CENTRAL NC WED-WED NIGHT. IT WILL ACCORDINGLY TURN QUITE MILD IN ADVANCE OF THE SYSTEM ON TUE...THOUGH TEMPERED A BIT OVER THE PIEDMONT WHERE STRATUS AND FOG WILL BE SLOW TO LIFT AND SCATTER. THIS STRATUS MOISTURE WILL BE TRAPPED BY A STRONG SUBSIDENCE INVERSION ALOFT AND RESULT IN RENEWED STRATUS DEVELOPMENT OVERNIGHT TUE...WITH TEMPERATURES APT TO RISE OVERNIGHT FROM LATE EVENING LOWS IN THE LOWER 50S ON AVERAGE. MILDER YET...TO WARM ON WED...IN STRONG SOUTHWESTERLY FLOW IN ADVANCE OF THE AFOREMENTIONED FRONTAL ZONE...WITH HIGHS WITHIN 5 DEGREES OF 70 WEST TO EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE FROM A THIRD OF AN INCH OVER THE COASTAL PLAIN TO THREE QUARTERS OF AN INCH OR SO OVER THE WESTERN PIEDMONT. STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS A GOOD PROBABILITY OF GOOD RADIATIONAL COOLING CONDITIONS. HOWEVER...MEDIUM RANGE GUIDANCE DOES INDICATE A S/W TROUGH ALOFT AND ACCOMPANYING CIRRUS SHIELD MAY OVERSPREAD THE MIDDLE ATLANTIC REGION AT THAT TIME...SO WILL NOT FORECAST - YET - THE UPPER TEENS THAT PROJECTED LOW LEVEL THICKNESSES WOULD SUGGEST. && .AVIATION /00Z SUNDAY THROUGH WEDNESDAY/... AS OF 740 PM SATURDAY... THE COMBINATION OF A MOIST SURFACE AIR MASS FROM RECENT PRECIP AND MOISTURE TRAPPED BELOW A STRONG SUBSIDENCE INVERSION AROUND 875 MB HAS LED POCKETS OF MVFR/IFR VISBYS AND/OR MVFR/IFR LOW STRATUS ACROSS EASTERN PORTIONS OF CENTRAL NC (KRDU/KRWI/KFAY) THIS EVENING. EXPECT THIS TO CONTINUE FOR AT LEAST THE REMAINDER OF THE EVENING. HOWEVER... SURFACE/LOW LEVEL HIGH PRESSURE IS EXPECTED TO BUILD INTO THE AREA OVERNIGHT FROM THE NORTH/NORTHWEST... WHICH MAY LEAD TO SOME DRIER AIR ADVECTING INTO THE REGION. MODEL GUIDANCE HAS BEEN TOO FAST IN SHOWING THE DRIER AIR WORKING INTO THE AREA THIS EVENING AT THE SURFACE. THIS COMBINED WITH DIFFERENCES IN 925 MB MOISTURE OVERNIGHT... MAKES THIS A RATHER LOW CONFIDENCE FORECAST. FOR NOW WILL SHOW MVFR/IFR CONDITIONS AT KFAY/KRWI/KRDU THIS EVENING (WITH POSSIBLY EVEN SOME LIFR VISBYS AT KRWI)... WITH VFR/HIGH END VFR CONDITIONS AT KGSO/KINT THIS EVENING. AFTER MIDNIGHT... CONFIDENCE DECREASES AT BIT WITH REGARD TO POSSIBLY SOME DRIER AIR ADVECTING INTO AREA. THINK WE MAY SEE SOME IMPROVEMENT IN THE VISBYS... WITH SPREADING LOW STRATUS (IFR/LOW END MVFR).... POSSIBLY EVEN SPREADING TO THE TRIAD TERMINALS (KGSO/KINT). IF SUB VFR CONDITIONS ARE ABLE TO SPREAD ACROSS ALL OF CENTRAL NC OVERNIGHT AND REMAIN THROUGH 12Z THINK WE WILL SEE CONDITIONS SLOWLY IMPROVE TO VFR ON SUNDAY... WITH SOME LOCATIONS ACROSS THE NORTH NOT SCATTERING AND LIFTING UNTIL MID AFTERNOON. A WEAK MID-UPPER DISTURBANCE WILL APPROACH AND CROSS THE REGION LATE SUNDAY NIGHT INTO EARLY MONDAY. THIS SYSTEM AND THE AVAILABLE MOISTURE IN THE ATMOSPHERE MAY TRIGGER A FEW PATCHES OF LIGHT PRECIPITATION ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. TEMPERATURES WILL BE CLOSE TO OR SLIGHTLY BELOW FREEZING...SO POCKETS OF FREEZING RAIN OR FREEZING DRIZZLE MAY OCCUR. CONFIDENCE LEVEL OF SEEING FREEZING PRECIPITATION IS ABOUT 33 PERCENT. IF FREEZING PRECIPITATION WERE TO OCCUR...IT WOULD AFFECT THE TRIAD TERMINALS AND POSSIBLY KRDU AND KRWI. OTHERWISE EXPECT MVFR CEILINGS WITH THIS SYSTEM MONDAY INTO MONDAY NIGHT. A BRIEF IMPROVEMENT IN AVIATION CONDITIONS EXPECTED TUESDAY THOUGH IT WILL BECOME BREEZY A WITH SW WIND GUSTING 20-25 MPH IN THE AFTERNOON. A STRONG COLD FRONT WILL APPROACH CENTRAL NC TUESDAY NIGHT AND CROSS THE AREA LATE WEDNESDAY INTO WEDNESDAY NIGHT. EXPECT CONTINUED BREEZY CONDITIONS AHEAD AND IMMEDIATELY BEHIND THE FRONT WITH A CHANCE OF MVFR CEILINGS WED-WED NIGHT ALONG WITH SCATTERED SHOWERS. IMPROVING WEATHER CONDITIONS ARE ANTICIPATED FOR THU... THROUGH IT IS EXPECTED TO REMAIN BREEZY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...WSS/MWS LONG TERM...MWS AVIATION...BSD/WSS
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1152 AM CST FRI JAN 25 2013 .DISCUSSION.../ISSUED AT 1140 AM CST/ COLD FRONT HAS PUSHED INTO NORTHEAST PORTIONS OF THE CWA AS OF 17Z AND STARTING TO SEE EFFECTS WITH TEMPERATURES FALLING OFF FROM BROOKINGS INTO MUCH OF NORTHERN COUNTIES OF SOUTHWEST MN OVER THE PAST HOUR OR TWO. EXPECT THIS TREND TO CONTINUE SOUTHWARD THROUGH THE AFTERNOON...ESPECIALLY EAST OF THE JAMES RIVER...THOUGH AREAS IMMEDIATELY BEHIND THE FRONT WILL LIKELY SEE TEMPERATURES BUMP UP WITH INITIAL STRONG MIXING BEFORE COLD ADVECTION TAKES OVER. THIS HAS RESULTED IN SOME TRICKY HOURLY TEMPERATURE FORECASTING THUS FAR THIS MORNING AS MODELS HAVING A HARD TIME CAPTURING DEGREE OF THIS INITIAL WARMING. HAVE MADE SOME ADJUSTMENTS TO HOURLY TEMPS/HIGHS SO FAR AND MORE LIKELY OVER THE NEXT COUPLE OF HOURS. ALSO ADJUSTED SKY GRIDS EARLIER TO CAPTURE NARROW BAND OF STRATUS DROPPING SOUTH ALONG/JUST AHEAD OF THE COLD FRONT. RAP SHOWS THIS BAND MOVING SLOWLY SOUTH BUT ALSO THINNING/DISSIPATING AS IT RUNS INTO SOME DRIER AIR...SO HAVE THUS FAR OPTED TO KEEP IT NORTH OF THE MISSOURI VALLEY...WHILE GRADUALLY DIMINISHING THE COVERAGE THROUGH THE AFTERNOON. WILL LIKELY MAKE FURTHER MINOR ADJUSTMENTS TO THIS AS WELL. POTENTIAL FOR A FEW FLURRIES ON THE BACK SIDE OF THE STRATUS AS TEMPERATURES IN CLOUD LAYER COOL BELOW -10C. WINDOW FOR THIS LOOKS RELATIVELY NARROW AND HAVE NOT ADDED TO THE GRIDS JUST YET... BUT WILL MONITOR CLOSELY. STRONGER WINDS BEHIND THE FRONT ALSO KICKING UP A LITTLE BLOWING SNOW WITH PIPESTONE/SLAYTON REPORTING SOME 4-5SM VISIBILITY WITHIN THE LAST HOUR. OVERALL SNOWPACK IS PRETTY SOLID THOUGH...SO EXPECT EFFECTS OF THIS TO LESSEN...WITH MORE OF A DRIFTING THAN BLOWING SNOW POTENTIAL IN HIGHER ELEVATIONS. UPDATED GRIDS HAVE BEEN SENT...AND WILL GET UPDATED ZFP/PFM OUT SHORTLY. && .AVIATION.../FOR THE 18Z TAF ISSUANCE/ NARROWING BAND OF MVFR STRATUS CONTINUES TO DROP SOUTHWARD JUST AHEAD OF COLD FRONT PUSHING INTO THE FORECAST AREA. CLOUD BAND ENCOUNTERING DRIER AIR AS IT TRIES TO PUSH TOWARD THE MISSOURI RIVER VALLEY...SO EXPECT KSUX TO REMAIN VFR THROUGH THE PERIOD. KFSD/KHON ON THE OTHER HAND...WILL SEE MVFR CONDITIONS FOR FIRST 2-4 HOURS OF THE TAF PERIOD...POTENTIALLY LONGER IN KHON AS WESTERN EXTENT OF THE STRATUS BAND WITHIN LOW LEVEL RIDGE AXIS IS MAKING LESS SOUTHWARD PROGRESS THAN AREAS FARTHER EAST. HOWEVER AT THIS TIME STILL EXPECT BOTH KFSD AND KHON BECOME VFR BY 26/00Z. DEEPER MIXING WITH INITIAL SURGE OF COLD ADVECTION BEHIND THE FRONT ENHANCING WIND GUSTS EAST OF THE JAMES RIVER...AND GUSTS OF 25-30KTS LIKELY EXPANDING FROM SOUTHWEST MN INTO NORTHWEST IOWA THROUGH THE EARLY-MID AFTERNOON. STRONGEST OF GUSTS EXPECTED TO REMAIN EAST OF KFSD/KSUX...THOUGH KFSD MAY SEE SOME BRIEF GUSTS TO AROUND 25KTS THROUGH 19-20Z. && .PREV DISCUSSION.../ISSUED AT 310 AM CST/ COLD FRONT WILL PUSH SOUTHEAST ACROSS CWA THIS MORNING...WITH MAIN BRUNT OF COOLING OVER NORTHEAST CWA WHERE TEMPERATURES WILL AGAIN BE BELOW NORMAL...WHILE SOUTHWEST CWA MIXES OUT TO ABOVE NORMAL. STRATUS DROPPING SOUTHEAST OUT OF NORTHEAST SD WILL SPREAD INTO SOUTHWEST MN THIS MORNING...SO EXPECT MOSTLY CLOUDY SKIES THERE THIS MORNING...WITH MOSTLY SUNNY SKIES ELSEWHERE. WILL BE A BIT BREEZY TODAY WITH NORTHWEST WINDS GUSTING TO 25 MPH AT TIMES. WIND WILL DROP OFF THIS EVENING...AND WILL ALLOW FOR ANOTHER COLD NIGHT...ESPECIALLY NORTHEAST WHERE LOWS WILL DROP BELOW ZERO. AGAIN WILL SEE A WIDE RANGE IN TEMPERATURES...WITH FAR SOUTHWEST CWA IN THE TEENS FOR LOWS. WARMER AIR WILL SPREAD NORTHEAST ACROSS CWA ON SATURDAY AS HIGH PRESSURE MOVES OFF INTO THE GREAT LAKES REGION. WILL SEE SOME INCREASE IN CLOUD COVER DURING THE DAY...ALONG WITH INCREASING SOUTHEAST WINDS. HIGHS WILL VARY FROM THE LOWER 20S OVER SOUTHWEST MN...TO THE LOWER 40S OVER GREGORY COUNTY. WAVE WILL PUSH EAST ACROSS THE CENTRAL PLAINS LATE SATURDAY NIGHT AND SUNDAY. GFS CONTINUES TO BE THE FURTHEST NORTH WITH THIS FEATURE WHILE BOTH ECMWF AND NAM KEEP IT WELL TO THE SOUTHEAST. IN FACT...ECMWF MUCH WEAKER AND ALMOST NON EXISTENT WITH WAVE. SO WILL NOT RAISE POPS AND WILL DECREASE A BIT ACROSS NORTHWEST IOWA. WITH WARMER AIR ALOFT OVER CWA...ANY PRECIPITATION THAT DOES OCCUR WILL EITHER BE LIGHT RAIN OR LIGHT FREEZING RAIN. THE MILD TEMPERATURES WILL PERSIST INTO MONDAY...BUT STRATUS MAY SPREAD NORTH INTO CWA AS WAVE PASSES BY TO THE SOUTH ON SUNDAY. SO THAT COULD HAVE AN EFFECT ON TEMPERATURES. STILL WILL SEE HIGHS 5 TO 10 DEGREES ABOVE NORMAL ACROSS CWA BOTH SUNDAY AND MONDAY. MODELS HAVE SHIFTED CONSIDERABLY FOR SYSTEM MONDAY NIGHT AND TUESDAY...WITH MODELS MUCH WEAKER AND ONLY LIGHT PRECIPITATION AT BEST. TIMING A BIT DIFFERENT WITH GFS MUCH QUICKER AND MUCH COLDER ON TUESDAY...WHILE ECMWF SLOWER AND WARMER. FOR NOW WILL TEND TO A CONSENSUS BLEND WHICH IS SLOWER THAN GFS. COLDER AIR WILL SPREAD SOUTHEAST ACROSS CWA TUESDAY NIGHT AND PERSIST INTO THURSDAY. TEMPERATURES SHOULD AGAIN BE BELOW NORMAL WEDNESDAY AND THURSDAY AS ARCTIC HIGH SETTLES SOUTH. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
925 PM CST SAT JAN 26 2013 .UPDATE... WE ARE ISSUING A DENSE FOG ADVISORY WITH THIS UPDATED FORECAST. THE ADVISORY EXTENDS EAST AND NORTH OF A LINE FROM BOWIE TO MERIDIAN TO PALESTINE. LOW VISIBILITIES HAVE ALREADY BEGUN FORMING IN THE WAXAHACHIE...CORSICANA...ATHENS AREA AND SHOULD CONTINUE TO INCREASE IN COVERAGE OVERNIGHT. AS THE WARM FRONT LIFTS NORTH ACROSS THE REGION...THEN DENSE FOG WILL SPREAD NORTHWARD WITH IT. ALSO...ADDED ANOTHER ROUND OF FOG FOR SUNDAY NIGHT...BUT THIS EVENT DOES NOT LOOK AS BAD AS TONIGHTS. 75 && .AVIATION... MAIN CONCERN TONIGHT IS THE LOW CIGS AND POTENTIAL FOR DENSE FOG. WARM FRONT IN CENTRAL TEXAS WILL HEAD NORTH ACROSS THE REGION DURING THE LATE NIGHT AND MORNING HOURS...WHICH SHOULD RESULT IN A GOOD SET UP FOR LOW CLOUDS AND FOG. ALREADY IFR CIGS ARE LOCATED JUST SOUTHEAST OF THE METROPLEX AND CIGS/VSBY DROP OFF EVEN MORE INTO EAST TEXAS. WILL BRING IFR CIGS INTO TAF SITES EARLY THIS EVENING...AND DROP THEM TO LIFR WITH MVFR VSBY BY 5Z. EXPECT CIGS TO DROP TO 200FT OR LESS WITH VSBY AT A HALF MILE OR LESS BY 7Z TO 9Z BASED ON RAP/NAM SOUNDINGS AND HRRR FORECASTS. SOUTH WINDS INCREASE OVERNIGHT TO 10 KT WHICH MAY HAVE THE EFFECT OF IMPROVING VSBY A LITTLE QUICKER THAN NORMAL...SO DENSE FOG MAY BE OVER BY 13Z...BUT VLIFR CIGS WOULD PROBABLY STICK AROUND A BIT LONGER. CIGS SHOULD GRADUALLY LIFT IN THE MID-LATE MORNING HOURS TO MVFR BY EARLY AFTERNOON...AND EVENTUALLY VFR BY MID AFTERNOON. SOUTH WINDS INCREASE TO 15-20KT TOMORROW AFTERNOON. WACO TAF IS MORE CHALLENGING IN THE SHORT TERM. SATELLITE SUGGESTS CIGS MAY LIFT COMPLETELY THIS EVENING...BUT THE WARM FRONT IS STILL TO THE SOUTH OF WACO THROUGH ABOUT 6Z. DENSE FOG MAY TRY TO DEVELOP BY MID EVENING BUT THIS WOULD PROBABLY IMPROVE LATE TONIGHT AS WARM FRONT MOVED NORTH OF WACO. EITHER WAY MVFR CIGS WILL LIKELY PREVAIL LATE TONIGHT THROUGH TOMORROW MORNING. TR.92 && .PREV UPDATE... .UPDATE... ISSUED NEW ZONES TO INCLUDE A MENTION OF FOG THIS EVENING AND WIDESPREAD FOG LATER TONIGHT. && .PREV DISCUSSION... /ISSUED 315 PM CST SAT JAN 26 2013/ CHALLENGING FORECAST...EVEN IN THE INTERIM. FORECAST CHALLENGE THROUGH SUNDAY MORNING CONTINUES TO BE WARM FRONT JUST ALONG THE SOUTHEAST EDGE OF THE CWA AND TIMING IT AS IT MOVES SLOWLY NORTH THROUGH THE AREA OVERNIGHT. LOW CLOUDS AND EVEN SOME PATCHY FOG OR SPRINKLES CONTINUES ACROSS CENTRAL AND NORTHEAST COUNTIES WITH A CLEARING LINE DENOTING THE WARM FRONT MOVING UP INTO MILAM... ROBERTSON...AND LEON COUNTIES THIS AFTERNOON. EXPECT THE WARM FRONT WILL REACH THE I-20 CORRIDOR SOMETIME BETWEEN MIDNIGHT AND SUNRISE SUNDAY. SOME VERY WEAK ISENTROPIC ASCENT OVER THE FRONT WILL LEND TO AREAS OF FOG AND POSSIBLY SOME PATCHY LIGHT DRIZZLE WITH A 30-40 KT LLJ OCCURRING ABOVE THE FRONTAL INVERSION. HAD THOUGHT ABOUT ADDING THE PATCHY DRIZZLE...BUT FOR NOW WILL KEEP THINGS SIMPLIFIED WITH THE FOG AS THE GROUND REMAINS COOL AND MOIST. FORECASTING LOWS WAS A CHALLENGE AS WELL WITH SOME TEMPERATURES HITTING LOWS MID EVENING...THEN STAYING STEADY OR EVEN RISING BEHIND THE WARM FRONT. SUNDAY MORNING SHOULD BE SIMILAR WITH REGARDS TO THE FOG AND CLOUDY CONDITIONS WITH SOUTHEAST WINDS SLOWLY INCREASING...AS THE WARM FRONT SHIFTS NORTH. DO EXPECT SOME IMPROVEMENT WITH PARTIAL SUNSHINE BY MID AFTERNOON AND WAA HELPING HIGHS WARM INTO THE LOW- MID 70S. INCREASING PRESSURE FALLS IN ADVANCE OF OUR WESTERN U.S UPPER TROUGH WILL RESULT IN BREEZY AND WARM CONDITIONS CONTINUING THROUGH MONDAY AND EVEN MONDAY NIGHT. OVERNIGHT LOWS WILL ONLY FALL INTO THE 50S/60S WITH HIGHS REBOUNDING BACK INTO THE 70S DESPITE MOSTLY CLOUDY CONDITIONS...THOUGH SOME SUNSHINE CAN BE EXPECTED IN THE AFTERNOON ONCE AGAIN. ANYWHERE WHERE WINDS DROP OFF ENOUGH AT NIGHT...SOME PATCHY FOG CAN BE EXPECTED. ALSO... DEEPENING MOISTURE ADVECTION COULD RESULT IN SPRINKLES OR ISOLATED VERY LIGHT SHOWERS LATE SUNDAY NIGHT AND EARLY MONDAY...BUT HAVE LEFT OUT FOR NOW UNTIL A BETTER IDEA ON THE INVERSION ALOFT AND WEAK ISENTROPIC LIFT IS GAINED. WITH TWO DIFFERENT PIECES OF SHORTWAVE ENERGY WITHIN THE BASE OF OUR APPROACHING SYSTEM...MODELS ARE STRUGGLING WITH EXACT STRENGTH AND TIMING OF LIFTING MECHANISMS AND THE PRE-FRONTAL TROUGH AND COLD FRONT LATER IN THE DAY TUESDAY AND TUESDAY NIGHT. THE EUROPEAN AND NORTH AMERICAN MODELS ARE DEEPEST AND SLOWEST WITH ALL AFOREMENTIONED FEATURES...WITH THE GFS THE MOST PROGRESSIVE. WE HAVE LEANED WITH A SLOWER SOLUTION CLOSER TO THE EURO/NORTH AMERICA WITH A STRONG BLOCKING RIDGE ACROSS THE EASTERN GULF OF MEXICO. WE EXPECT AN INITIAL SHORTWAVE AND ASSOCIATED NOCTURNAL LLJ/WAA TO RESULT IN ELEVATED CONVECTION LATE MONDAY NIGHT/EARLY TUESDAY FROM AREAS NORTH OF I-20 INTO OKLAHOMA AND THE ARKLATEX ESPECIALLY. BY AFTERNOON...THE PRE-FRONTAL TROUGH SHOULD BEGIN TO MIX EASTWARD IN RESPONSE TO HEIGHT FALLS AND THE SURFACE LOW EJECTING TOWARD KANSAS CITY TUESDAY MORNING. WITH THE INVERSION ALOFT LIFTING AND MOISTENING...MORE SURFACE BASED CONVECTION SHOULD DEVELOP ALONG THE PRE-FRONTAL TROUGH AS IT PUSHES TOWARD THE I-35 CORRIDOR BY TUESDAY AFTERNOON. HAVE RAISED POPS SLIGHTLY ACROSS THE NORTHEAST HALF OF THE AREA WHERE TIMING OF LIFT WILL MESH THE BEST WITH DAYTIME HEATING AND BETTER INSTABILITY. HARD TO SAY ON THE SEVERE WEATHER THREAT...BUT DO FEEL AREAS EAST OF I-35 WILL LIKELY SEE SOME CHANCE OF STRONG TO SEVERE STORMS OCCURRING WITH SUFFICIENT EFFECTIVE SWLY BULK SHEAR 50-70 KTS AND LAPSE RATES ALOFT BETWEEN 6.5-7 DEG C/KM. IN ADDITION TO THE STORM CHANCES AND WARM TEMPERATURES...A VERY STRONG PRESSURE GRADIENT WILL RESULT IN SOME GUSTY SOUTHWEST WINDS AHEAD OF THE SURFACE TROUGH...WITH VERY GUSTY WEST WINDS BEHIND IT ON TUESDAY AFTERNOON. THE THREAT FOR SHOWERS AND STORMS WILL LINGER INTO THE EVENING HOURS ACROSS THE FAR EASTERN COUNTIES...BEFORE A STRONG COLD FRONT OVERTAKES THE TROUGH WITH STRONG CAA AND BRISK CONDITIONS OCCURRING OVERNIGHT. LINGERING SHORTWAVE ENERGY...HAVE HELD ONTO SOME SHOWERS LINGERING ACROSS THE EASTERN COUNTIES OVERNIGHT. BRISK AND MUCH COOLER CONDITIONS ON WEDNESDAY/THURSDAY WITH HIGHS STRUGGLING TO GET OUT OF THE 50S MOST LOCATIONS WITH COOL CYCLONIC FLOW OVERHEAD. FLOW ALOFT GRADUALLY DAMPENS FRIDAY INTO NEXT WEEKEND WHICH WILL ALLOW FOR A SLOW WARM UP AND RETURN FLOW FROM THE SOUTH. IT WILL REMAIN DRY THROUGH NEXT WEEKEND. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 53 74 62 76 64 / 10 10 10 10 20 WACO, TX 56 74 61 76 64 / 10 10 10 10 20 PARIS, TX 46 70 58 75 61 / 10 10 10 10 20 DENTON, TX 51 73 61 75 62 / 10 10 10 10 20 MCKINNEY, TX 49 72 62 74 63 / 10 10 10 10 20 DALLAS, TX 54 73 63 75 64 / 10 10 10 10 20 TERRELL, TX 51 73 60 75 63 / 10 10 10 10 20 CORSICANA, TX 56 74 61 77 63 / 10 10 10 10 20 TEMPLE, TX 58 74 61 76 64 / 10 10 10 10 20 MINERAL WELLS, TX 54 74 58 76 58 / 10 10 10 10 20 && .FWD WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR TXZ091>095-102>107- 117>123-131>135-144>148. && $$ /75
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
524 PM CST SAT JAN 26 2013 .AVIATION... MAIN CONCERN TONIGHT IS THE LOW CIGS AND POTENTIAL FOR DENSE FOG. WARM FRONT IN CENTRAL TEXAS WILL HEAD NORTH ACROSS THE REGION DURING THE LATE NIGHT AND MORNING HOURS...WHICH SHOULD RESULT IN A GOOD SET UP FOR LOW CLOUDS AND FOG. ALREADY IFR CIGS ARE LOCATED JUST SOUTHEAST OF THE METROPLEX AND CIGS/VSBY DROP OFF EVEN MORE INTO EAST TEXAS. WILL BRING IFR CIGS INTO TAF SITES EARLY THIS EVENING...AND DROP THEM TO LIFR WITH MVFR VSBY BY 5Z. EXPECT CIGS TO DROP TO 200FT OR LESS WITH VSBY AT A HALF MILE OR LESS BY 7Z TO 9Z BASED ON RAP/NAM SOUNDINGS AND HRRR FORECASTS. SOUTH WINDS INCREASE OVERNIGHT TO 10 KT WHICH MAY HAVE THE EFFECT OF IMPROVING VSBY A LITTLE QUICKER THAN NORMAL...SO DENSE FOG MAY BE OVER BY 13Z...BUT VLIFR CIGS WOULD PROBABLY STICK AROUND A BIT LONGER. CIGS SHOULD GRADUALLY LIFT IN THE MID-LATE MORNING HOURS TO MVFR BY EARLY AFTERNOON...AND EVENTUALLY VFR BY MID AFTERNOON. SOUTH WINDS INCREASE TO 15-20KT TOMORROW AFTERNOON. WACO TAF IS MORE CHALLENGING IN THE SHORT TERM. SATELLITE SUGGESTS CIGS MAY LIFT COMPLETELY THIS EVENING...BUT THE WARM FRONT IS STILL TO THE SOUTH OF WACO THROUGH ABOUT 6Z. DENSE FOG MAY TRY TO DEVELOP BY MID EVENING BUT THIS WOULD PROBABLY IMPROVE LATE TONIGHT AS WARM FRONT MOVED NORTH OF WACO. EITHER WAY MVFR CIGS WILL LIKELY PREVAIL LATE TONIGHT THROUGH TOMORROW MORNING. TR.92 && .UPDATE... ISSUED NEW ZONES TO INCLUDE A MENTION OF FOG THIS EVENING AND WIDESPREAD FOG LATER TONIGHT. && .PREV DISCUSSION... /ISSUED 315 PM CST SAT JAN 26 2013/ CHALLENGING FORECAST...EVEN IN THE INTERIM. FORECAST CHALLENGE THROUGH SUNDAY MORNING CONTINUES TO BE WARM FRONT JUST ALONG THE SOUTHEAST EDGE OF THE CWA AND TIMING IT AS IT MOVES SLOWLY NORTH THROUGH THE AREA OVERNIGHT. LOW CLOUDS AND EVEN SOME PATCHY FOG OR SPRINKLES CONTINUES ACROSS CENTRAL AND NORTHEAST COUNTIES WITH A CLEARING LINE DENOTING THE WARM FRONT MOVING UP INTO MILAM... ROBERTSON...AND LEON COUNTIES THIS AFTERNOON. EXPECT THE WARM FRONT WILL REACH THE I-20 CORRIDOR SOMETIME BETWEEN MIDNIGHT AND SUNRISE SUNDAY. SOME VERY WEAK ISENTROPIC ASCENT OVER THE FRONT WILL LEND TO AREAS OF FOG AND POSSIBLY SOME PATCHY LIGHT DRIZZLE WITH A 30-40 KT LLJ OCCURRING ABOVE THE FRONTAL INVERSION. HAD THOUGHT ABOUT ADDING THE PATCHY DRIZZLE...BUT FOR NOW WILL KEEP THINGS SIMPLIFIED WITH THE FOG AS THE GROUND REMAINS COOL AND MOIST. FORECASTING LOWS WAS A CHALLENGE AS WELL WITH SOME TEMPERATURES HITTING LOWS MID EVENING...THEN STAYING STEADY OR EVEN RISING BEHIND THE WARM FRONT. SUNDAY MORNING SHOULD BE SIMILAR WITH REGARDS TO THE FOG AND CLOUDY CONDITIONS WITH SOUTHEAST WINDS SLOWLY INCREASING...AS THE WARM FRONT SHIFTS NORTH. DO EXPECT SOME IMPROVEMENT WITH PARTIAL SUNSHINE BY MID AFTERNOON AND WAA HELPING HIGHS WARM INTO THE LOW- MID 70S. INCREASING PRESSURE FALLS IN ADVANCE OF OUR WESTERN U.S UPPER TROUGH WILL RESULT IN BREEZY AND WARM CONDITIONS CONTINUING THROUGH MONDAY AND EVEN MONDAY NIGHT. OVERNIGHT LOWS WILL ONLY FALL INTO THE 50S/60S WITH HIGHS REBOUNDING BACK INTO THE 70S DESPITE MOSTLY CLOUDY CONDITIONS...THOUGH SOME SUNSHINE CAN BE EXPECTED IN THE AFTERNOON ONCE AGAIN. ANYWHERE WHERE WINDS DROP OFF ENOUGH AT NIGHT...SOME PATCHY FOG CAN BE EXPECTED. ALSO... DEEPENING MOISTURE ADVECTION COULD RESULT IN SPRINKLES OR ISOLATED VERY LIGHT SHOWERS LATE SUNDAY NIGHT AND EARLY MONDAY...BUT HAVE LEFT OUT FOR NOW UNTIL A BETTER IDEA ON THE INVERSION ALOFT AND WEAK ISENTROPIC LIFT IS GAINED. WITH TWO DIFFERENT PIECES OF SHORTWAVE ENERGY WITHIN THE BASE OF OUR APPROACHING SYSTEM...MODELS ARE STRUGGLING WITH EXACT STRENGTH AND TIMING OF LIFTING MECHANISMS AND THE PRE-FRONTAL TROUGH AND COLD FRONT LATER IN THE DAY TUESDAY AND TUESDAY NIGHT. THE EUROPEAN AND NORTH AMERICAN MODELS ARE DEEPEST AND SLOWEST WITH ALL AFOREMENTIONED FEATURES...WITH THE GFS THE MOST PROGRESSIVE. WE HAVE LEANED WITH A SLOWER SOLUTION CLOSER TO THE EURO/NORTH AMERICA WITH A STRONG BLOCKING RIDGE ACROSS THE EASTERN GULF OF MEXICO. WE EXPECT AN INITIAL SHORTWAVE AND ASSOCIATED NOCTURNAL LLJ/WAA TO RESULT IN ELEVATED CONVECTION LATE MONDAY NIGHT/EARLY TUESDAY FROM AREAS NORTH OF I-20 INTO OKLAHOMA AND THE ARKLATEX ESPECIALLY. BY AFTERNOON...THE PRE-FRONTAL TROUGH SHOULD BEGIN TO MIX EASTWARD IN RESPONSE TO HEIGHT FALLS AND THE SURFACE LOW EJECTING TOWARD KANSAS CITY TUESDAY MORNING. WITH THE INVERSION ALOFT LIFTING AND MOISTENING...MORE SURFACE BASED CONVECTION SHOULD DEVELOP ALONG THE PRE-FRONTAL TROUGH AS IT PUSHES TOWARD THE I-35 CORRIDOR BY TUESDAY AFTERNOON. HAVE RAISED POPS SLIGHTLY ACROSS THE NORTHEAST HALF OF THE AREA WHERE TIMING OF LIFT WILL MESH THE BEST WITH DAYTIME HEATING AND BETTER INSTABILITY. HARD TO SAY ON THE SEVERE WEATHER THREAT...BUT DO FEEL AREAS EAST OF I-35 WILL LIKELY SEE SOME CHANCE OF STRONG TO SEVERE STORMS OCCURRING WITH SUFFICIENT EFFECTIVE SWLY BULK SHEAR 50-70 KTS AND LAPSE RATES ALOFT BETWEEN 6.5-7 DEG C/KM. IN ADDITION TO THE STORM CHANCES AND WARM TEMPERATURES...A VERY STRONG PRESSURE GRADIENT WILL RESULT IN SOME GUSTY SOUTHWEST WINDS AHEAD OF THE SURFACE TROUGH...WITH VERY GUSTY WEST WINDS BEHIND IT ON TUESDAY AFTERNOON. THE THREAT FOR SHOWERS AND STORMS WILL LINGER INTO THE EVENING HOURS ACROSS THE FAR EASTERN COUNTIES...BEFORE A STRONG COLD FRONT OVERTAKES THE TROUGH WITH STRONG CAA AND BRISK CONDITIONS OCCURRING OVERNIGHT. LINGERING SHORTWAVE ENERGY...HAVE HELD ONTO SOME SHOWERS LINGERING ACROSS THE EASTERN COUNTIES OVERNIGHT. BRISK AND MUCH COOLER CONDITIONS ON WEDNESDAY/THURSDAY WITH HIGHS STRUGGLING TO GET OUT OF THE 50S MOST LOCATIONS WITH COOL CYCLONIC FLOW OVERHEAD. FLOW ALOFT GRADUALLY DAMPENS FRIDAY INTO NEXT WEEKEND WHICH WILL ALLOW FOR A SLOW WARM UP AND RETURN FLOW FROM THE SOUTH. IT WILL REMAIN DRY THROUGH NEXT WEEKEND. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 53 74 62 76 64 / 10 10 10 10 20 WACO, TX 56 74 61 76 64 / 10 10 10 10 20 PARIS, TX 46 70 58 75 61 / 10 10 10 10 20 DENTON, TX 51 73 61 75 62 / 10 10 10 10 20 MCKINNEY, TX 49 72 62 74 63 / 10 10 10 10 20 DALLAS, TX 54 73 63 75 64 / 10 10 10 10 20 TERRELL, TX 51 73 60 75 63 / 10 10 10 10 20 CORSICANA, TX 56 74 61 77 63 / 10 10 10 10 20 TEMPLE, TX 58 74 61 76 64 / 10 10 10 10 20 MINERAL WELLS, TX 54 74 58 76 58 / 10 10 10 10 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1156 AM CST FRI JAN 25 2013 .AVIATION... SW FLOW THIS AFTERNOON WITH SOME GUSTS NEAR 20 KTS POSSIBLE. PATCHY MVFR CIGS SHOULD RISE TO NEAR 3000FT BY 20Z AND SCATTER OUT. GRADIENT RELAXES LATE THIS AFTERNOON AS LLJ OVER NETX PULLS AWAY AND WINDS RESPOND TO ABUNDANT HEATING OVER THE SOUTHERN HALF OF TX...COLD FRONT STALLING NEAR LHB-DKR-OCH. BY EARLY EVENING EXPECT WINDS TO BACK TO THE SOUTH AND SOUTH-SOUTHEAST WHICH MAY SET THE STAGE FOR A NIGHT OF FOG OVER MUCH OF THE TERMINALS...EVEN WITHOUT THE FOG EXPECT IFR CIGS. VISBY ESPECIALLY FOR HOU SOUTHWARD SHOULD DROP INTO THE 1/2 TO 0 RANGE. IMPROVEMENT WILL BE SLOW TO VERY SLOW AFTER 15Z SATURDAY WITH IFR CONDITIONS LINGERING THROUGH 18Z. IF THE RAP IS CORRECT THEN MORE BACKED WINDS WILL PREVAIL AFTER 03Z AND FOG COULD REACH FARTHER INLAND. HAVE LOWER FLIGHT CATEGORY FORECASTS BUT NOT AS PESSIMISTIC AS RAP ATTM. 45 && .PREV DISCUSSION... /ISSUED 1023 AM CST FRI JAN 25 2013/ DISCUSSION... THE COLD FRONT THAT HAS PUSHED THROUGH MUCH OF NORTH TEXAS APPEARS TO BE STALLING OUT JUST NORTH OF OUR REGION THIS MORNING AND IS NOT EXPECTED TO MAKE MUCH MORE PROGRESS TO THE SOUTH. WITH CLOUDS SCATTERING OUT ACROSS SOUTHEAST TEXAS AND TEMPERATURES AT OR ABOVE WHERE THEY WERE THIS TIME YESTERDAY WE SHOULD SEE MOST LOCATIONS REACH THE UPPER 70S TO NEAR 80 DEGREES THIS AFTERNOON. CURRENT FORECAST IS IN GOOD SHAPE AND NO UPDATES PLANNED THIS MORNING. 38 MARINE... SOUTHERLY FLOW CONTINUING...WELL OFFSHORE WINDS NEAR 15 KNOTS THIS MORNING SHOULD GRADUALLY COME DOWN THIS AFTERNOON AND EVENING. BUMPED UP SEAS A FOOT. SEA FOG STILL LOOKS LIKE A GOOD BET GIVEN THE LIGHTER MORE BACKED WINDS AND THE ALREADY HIGH DEWPOINTS IN THE LOWER TO MID 60S. 45 AVIATION... LOW CIGS ON THE RISE BUT EXPECT THE CIGS TO HOLD IN THE MVFR RANGE THRU 18Z AND THEN MIX OUT THIS AFTERNOON. EXPECT MORE FOG TONIGHT AND FROM THE COAST AND PROBABLY UP THROUGH UTS. 45 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 79 61 77 59 75 / 0 10 10 10 10 HOUSTON (IAH) 80 61 79 60 77 / 0 10 10 10 10 GALVESTON (GLS) 73 63 72 62 71 / 0 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...38 AVIATION/MARINE...45
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
345 PM CST FRI JAN 25 2013 .SHORT TERM... TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH. ONGOING LIGHT SNOW IN THE EAST DUE TO PERSISTENT Q-VECTOR CONVERGENCE AND MID LEVEL OMEGA OVER THE REGION AND LOW LEVEL MOISTURE IN THE DENDRITE GROWTH ZONE PER RAP SOUNDINGS. THE DRY SLOT BETWEEN THE SOUTHWEST WINDS AND THE COLD FRONT IS GRADUALLY CLOSING UP AS THE COLD FRONT IS CATCHING UP. IT HAS PROGRESSED INTO PORTIONS OF SOUTH CENTRAL WI INCLUDING THE DELLS AS OF 330 PM. THERE IS AN AREA OF SNOW SHOWERS WITH INCREASING REFLECTIVITY NEAR MADISON WITH WEST WINDS...BASICALLY ALIGNED WITH A PRE-FRONTAL TROUGH. THIS WILL CONTINUE TO MOVE INTO SOUTHEAST WI THROUGH 00Z. THE LOW LEVEL LAPSE RATES ARE INCREASING DUE TO DIFFERENTIAL VORTICITY ADVECTION AND THIS IS CREATING A MORE CONVECTIVE LOOK TO THE SNOW SHOWERS ON RADAR. THE COLD FRONT CHARACTERIZED BY THE SURFACE WIND SHIFT TO WNW ALREADY AT THE DELLS WILL MAKE ITS WAY ACROSS SOUTHERN WI THROUGH 03Z THIS EVENING. A TWO HOUR PERIOD OF CONVECTIVE-LOOKING SNOW SHOWERS IS EXPECTED AT EACH SITE. HIGHER POPS IN THE NORTHERN FORECAST AREA AND LOWER POPS ALONG THE ILLINOIS BORDER. THESE SHOULD EXIT MILWAUKEE AND SHEBOYGAN BY 03Z. A QUICK HALF INCH OF SNOW IS NOT OUT OF THE QUESTION...ALONG WITH BRIEF PERIODS OF LOWER VISIBILITY WITH SOME GUSTY NORTHWEST WINDS. SKIES SHOULD CLEAR FAIRLY QUICKLY FROM WEST TO EAST DURING THE EVENING AS LOW PRESSURE EXITS AND HIGH PRESSURE BUILDS INTO THE REGION. WINDS WILL DECREASE OVERNIGHT AS WELL...AND TEMPERATURES WILL DROP INTO THE SINGLE DIGITS INLAND FROM THE LAKE. SATURDAY...FORECAST CONFIDENCE HIGH. IT WILL BE A QUIET WEATHER DAY WITH HIGH PRESSURE OVERHEAD. PLENTY OF SUNSHINE IS EXPECTED IN THE MORNING. THEN HIGH CLOUDS WILL BEGIN TO SPREAD INTO SOUTHERN WI LATE IN THE AFTERNOON. HIGHS EXPECTED TO WARM INTO THE LOWER 20S. SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM SLY WINDS WILL DEVELOP SAT NT AS A SHORTWAVE TROUGH MOVES INTO THE CENTRAL PLAINS WITH LEE SIDE CYCLOGENESIS. MID LEVEL WARM ADVECTION WELL AHEAD OF THE SHORTWAVE WILL BRING SCT-BKN MID LEVEL CLOUDS FOR SAT NT WITH LOW TEMPS COOLING ONLY INTO THE TEENS. THE SHORTWAVE TROUGH WILL THEN REACH THE MS RIVER BY 00Z MON WITH A WAVE OF LOW PRESSURE REACHING IA. THE WAVE OF LOW PRESSURE WILL THEN APPROXIMATELY MOVE ACROSS THE WI/IL BORDER SUN NT INTO MON. ORGANIZED WARM ADVECTION AND FRONTOGENESIS IN THE 850-600 MB LAYER WILL SHIFT NEWD THROUGH SRN WI SUN AFTERNOON AND NIGHT WITH PWS INCREASING TO NEARLY 0.80 INCHES. A WARM LAYER ALOFT OF 2-4C WILL MOVE NWD ACROSS SRN WI DURING THIS TIME WHILE SFC TEMPS REMAIN BELOW FREEZING FOR SOME TIME. THUS SEE THE PCPN BEGINNING AS SNOW...THEN SNOW AND SLEET...AND POSSIBLY TRANSITIONING TO ALL FREEZING RAIN IN THE SRN HALF OF THE CWA. A MODELS CONSENSUS OF QPF FOR SUN AND SUN NT RANGES FROM 0.35-0.45 INCHES ACROSS THE CWA. THIS CONVERTS TO A COUPLE INCHES OF SNOW IN THE NRN CWA TO UNDER AN INCH IN THE SOUTH. ICE ACCUMS RANGE FROM 0.10-0.24 INCHES WITH THE LESSER AMOUNTS IN THE NORTH AND FAR EAST WHERE EITHER MORE SNOW WILL OCCUR OR TEMPS WILL BE MILDER. ICE ACCUM FORECAST IS DIFFICULT SUN NT SINCE TEMPS WILL BE RISING TO OR ABOVE FREEZING. CURRENTLY THINK THIS IS AN ADVISORY SITUATION BUT WILL ISSUE A SPECIAL WEATHER STATEMENT FOR NOW. .LONG TERM...FORECAST CONFIDENCE LOW TO MEDIUM A FAIRLY DEEP UPPER TROUGH WILL TRACK EAST ACROSS THE COUNTRY NEXT WEEK BUT THE DETAILS OF TIMING AND CYCLOGENESIS ARE UNKNOWN DUE TO A LARGE MODEL SPREAD. MILDER TEMPS HOWEVER SHOULD BE OVER THE AREA MON-TUE WITH A STRONG COLD FRONT ARRIVING TUE NT OR WED. THERE WILL BE CHANCES OF RAIN...THEN SNOW DURING THIS TIME. BRISK NWLY WINDS AND COLD ADVECTION TO THEN PREVAIL THROUGH THU FOLLOWED BY POLAR HIGH PRESSURE FOR FRIDAY. && .AVIATION/00Z TAFS/... AREA OF VFR CIGS WITH WEST WINDS AND SNOW SHOWERS OVER SOUTH CENTRAL WI IS MOVING INTO SOUTHEAST WI THIS AFTERNOON. A COLD FRONT THAT JUST CLEARED THE DELLS AROUND 3 PM WITH A WIND SHIFT TO NORTHWEST WILL HIT MSN AROUND 4PM AND MKE JUST AFTER 00Z EARLY THIS EVENING. EXPECTING ABOUT A 2 HOUR PERIOD OF SNOW SHOWERS THAT COULD BRING THE VSBY DOWN TO AROUND 2 MILES FOR A SHORT PERIOD OF TIME WITH THE COLD FRONT. THEN WINDS WILL GRADUALLY DIE DOWN THROUGH THE NIGHT AND SKIES ARE EXPECTED TO CLEAR. CLEAR SKIES WILL GIVE WAY TO SOME HIGH CLOUDS SATURDAY AFTERNOON WITH SOUTH WINDS DEVELOPING LATE IN THE DAY. && .MARINE...NORTHWEST WINDS BEHIND A COLD FRONT WILL INCREASE TO MARGINAL SMALL CRAFT ADVISORY CONDITIONS EARLY THIS EVENING AND PERSIST OVERNIGHT. WINDS WILL DIMINISH SATURDAY MORNING AS HIGH PRESSURE BUILDS INTO THE REGION. SMALL CRAFT ADVY IN EFFECT 6PM THIS EVENING TO 6AM SAT MORNING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR LMZ643>646. && $$ TONIGHT/SATURDAY AND AVIATION/MARINE...MRC SATURDAY NIGHT THROUGH FRIDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
535 AM CST FRI JAN 25 2013 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 325 AM CST FRI JAN 25 2013 MAIN FORECAST CONCERNS ARE ON SNOW AND WIND POTENTIAL TODAY...THEN IF PRECIPITATION CAN OCCUR AND WHAT TYPE FOR SUNDAY INTO SUNDAY NIGHT. CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT TROUGH OFF THE PACIFIC NORTHWEST COAST...RIDGING OVER THE NORTHERN U.S. ROCKIES INTO ALBERTA...A SHORTWAVE TROUGH DIGGING INTO NORTHWEST MINNESOTA...AND A SHORTWAVE OVER SOUTHEAST MINNESOTA. AHEAD OF THIS LATTER SHORTWAVE...WATER VAPOR...IR IMAGERY AND SURFACE OBSERVATIONS SHOWED A LARGE EXPANSE OF MID AND HIGH CLOUDS. RAP TROPOPAUSE ANALYSIS ALSO HAD A BROAD 120-140KT JET FROM NEBRASKA TO OHIO DOWNSTREAM OF THE SHORTWAVE...ACTUALLY PLACING THE FORECAST AREA IN THE SUBSIDENT LEFT ENTRANCE REGION. 00Z SOUNDINGS FROM MPX...GRB AND DVN SHOWED A GREAT DEAL OF DRY AIR BELOW 700MB...WITH DEWPOINT DEPRESSIONS AS MUCH AS 30C. THIS DRY AIR HAS BEEN EFFECTIVE AT MINIMIZING SNOWFALL OUT OF THE MID/HIGH CLOUDS FROM REACHING THE SURFACE. THERE WAS HIGHER LOWER LEVEL MOISTURE OFF TO THE WEST AT ABR AND OAX...NOTED BY ITS 00Z SOUNDING HAVING 850MB DEWPOINT DEPRESSION BETWEEN 1-5C. THIS HAS BEEN SLOWLY ADVECTING TOWARDS THE AREA REFLECTED BY SOUTHWEST 25-40KT WINDS ON PROFILER AND VWP DATA. BETWEEN 06-08Z...SOME SNOW FINALLY GOT GOING...BUT THE BACK EDGE BEHIND THE LEAD SHORTWAVE WAS RAPIDLY PUSHING EAST...WITH KRST AND KCCY NOW DRY. TO THE NORTH...A BAND OF WARM ADVECTION SNOW HAS BEEN ONGOING FROM NORTHERN MN INTO NORTHERN WI...DOWNSTREAM OF THE NORTHWEST MN SHORTWAVE TROUGH. IN THE WAKE OF THIS SHORTWAVE TROUGH...ANOTHER SURGE OF ARCTIC AIR WAS NOTED WITH TEMPERATURES IN THE TEENS AND 20S BELOW ZERO OVER CENTRAL SASKATCHEWAN. THE COLD AIR WAS IN THE WAKE OF A 1012MB SURFACE LOW IN NORTHWEST MN. TODAY AND TONIGHT...MODELS ARE IN GOOD AGREEMENT DROPPING THE SHORTWAVE TROUGH OVER NORTHWEST MINNESOTA ACROSS CENTRAL WISCONSIN BY 18Z...THEN INTO SOUTHEAST LOWER MI BY 00Z. 500MB HEIGHTS SLOWLY RISE THEREAFTER AS THE NORTHERN ROCKIES RIDGE SLIDES EASTWARD... PLACING THE FORECAST AREA IN AN INFLECTION POINT BETWEEN A TROUGH AND RIDGE AXIS BY 12Z SATURDAY. THE TROPOPAUSE DROPS NICELY THIS MORNING WITH THE SHORTWAVE TROUGH MOVING IN...AS MUCH AS 100MB TO NEAR 350MB ACROSS MUCH OF WISCONSIN BY 15Z. ALTHOUGH THIS IS GOOD DYNAMIC FORCING...THE SCOURING OUT OF MID AND UPPER LEVEL MOISTURE BY THE LEAD SHORTWAVE AHEAD OF THE TROUGH IS VERY PROBLEMATIC. AS SUCH...MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION WITH THE WARM ADVECTION AND DPVA AHEAD OF THE SYSTEM. THIS MATCHES TOO WITH RADAR TRENDS...AND THUS HAVE SHORTENED THE END TIME OF THE ADVISORY TO 12Z. IN FACT...WE MAY HAVE TO WAIT UNTIL THE AFTERNOON...WHEN SNOW ACTUALLY LOOKS BETTER IN THE WAKE OF THE SHORTWAVE TROUGH AND SURFACE LOW. THIS IS DUE TO COLD ADVECTION COMBINING WITH LINGERING SURFACE MOISTURE TO PRODUCE CONVECTIVE SNOW. THE 25.00Z NAM AND HIRES NMM RUNS ARE THE MOST BULLISH WITH THE CONVECTIVE IDEA...WHILE ARW MODELS ARE NOT. IT APPEARS THE NMM CORE MAY BE MOISTENING SURFACE DEWPOINTS UP TOO MUCH. TOOK A COMPROMISE APPROACH WHICH RESULTS IN FLURRIES ALONG THE MS RIVER AND SCATTERED SNOW SHOWERS NORTH OF I-94 WHERE THE BEST LOW LEVEL INSTABILITY IS PRESENT. IN ADDITION TO THE SNOW...SETUP FOR THE AFTERNOON IS FAVORABLE FOR WINDY CONDITIONS. THE COMBINATION OF COLD ADVECTION...A TIGHT PRESSURE GRADIENT IN THE WAKE OF THE LOW...BEING AT PEAK HEATING AND MIXING DEPTHS UP TO 875-900MB SHOULD YIELD GUSTS IN THE 25-30 KT RANGE. EXPECT THE SNOW TO QUICKLY DIMINISH THIS EVENING WITH LOSS OF HEATING AND THE SHORTWAVE TROUGH SHIFTING OFF. WINDS LOOK TO TAKE SOME TIME DIMINISHING SINCE THE HIGH PRESSURE AREA DOES NOT BUILD IN UNTIL LATE IN THE NIGHT...I.E. AT THE TIME OF THE INFLECTION POINT IN THE FLOW AT 500MB. THE COMBINATION OF WIND AND MUCH OF THE AREA STILL WITH NEAR BARE GROUND WILL KEEP LOWS WARMER...ESPECIALLY COMPARED TO THE NAM WHICH HAS 5 INCHES ON THE GROUND ACROSS THE FORECAST AREA. LEANED CLOSER TO THE ECMWF AND MAV GUIDANCE FOR LOWS. SATURDAY AND SATURDAY NIGHT...THE UPPER RIDGING OVER THE NORTHERN ROCKIES IS PROGGED TO CONTINUE MARCHING EAST TOWARDS THE FORECAST AREA DURING THIS TIME PERIOD...PUSHED ALONG BY TROUGHING OFF THE PACIFIC NORTHWEST MOVING INLAND AS WELL AS AN UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING INTO SOUTHEAST COLORADO. THE SHIFT EAST OF THE UPPER RIDGE AXIS...REACHING EASTERN MN BY 12Z SUNDAY...WILL SETUP A LOW LEVEL RETURN FLOW OVER THE FORECAST AREA FOR THE AFTERNOON AND NIGHT. AN INCREASE OF MID/HIGH CLOUDS IS LIKELY GIVEN THE WARM ADVECTION PATTERN...NOTED TOO BY 925MB TEMPS CLIMBING FROM AROUND -12C AT 12Z SATURDAY TO -2 TO -6C BY 12Z SUNDAY. THE QUESTION MARK IS LATE SATURDAY NIGHT...IF THE LOW LEVEL MOISTURE WILL BE DEEP ENOUGH TO RESULT IN PRECIPITATION. THE 25.00Z NAM/CANADIAN SUGGESTS THIS WOULD OCCUR FROM THE KANSAS CITY AREA INTO NORTHEAST IOWA. COMPARED TO THE 25.00Z GFS/ECMWF/UKMET... THIS SEEMS A LITTLE TOO FAR NORTH / FAST. THE OTHER MODEL GROUP KEEPS THE BULK OF THE WARM ADVECTION PRECIPITATION SOUTH OF I-80. THUS...HAVE KEPT THE ENTIRE PERIOD FROM 12Z SATURDAY TO 12Z SUNDAY DRY. WITH THE WARMING 925MB TEMPS AND SOME SUN...HIGHS SHOULD BOUNCE BACK INTO THE TEENS FOR SATURDAY. WARM ADVECTION PERSISTING THROUGH THE NIGHT PLUS CLOUDS AROUND WILL LEAD TO RISING TEMPERATURES SATURDAY NIGHT. SUNDAY AND SUNDAY NIGHT...THIS PERIOD REMAINS VERY PROBLEMATIC AND UNCERTAIN. THE MAIN PROBLEM IS THE STRENGTH AND SPEED OF THE UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING UP TOWARDS THE AREA ON SUNDAY. THE SPREAD RANGES FROM: 1. A RELATIVELY STRONG 25.00Z GFS/CANADIAN...STILL SHOWING AT LEAST A POTENT SHORTWAVE COMING THROUGH THE FORECAST AREA AROUND 06Z MONDAY. 2. A REALLY WEAK 24.12Z/25.00Z ECMWF WHICH SHEAR THE UPPER LOW APART AND HAVE ITS REMNANTS TRACK ALONG I-80. THE 25.00Z NAM/UKMET LIE IN-BETWEEN THESE SCENARIOS. THE DIFFERENCES NOT ONLY IMPACT WHETHER IT WILL PRECIPITATE...BUT ALSO WHAT TYPE WOULD OCCUR IF IT DOES PRECIPITATE. THE ECMWF...BEING THE WEAKEST...LIMITS THE AMOUNT OF MOISTURE RETURN INTO THE FORECAST AREA FROM THE GULF OF MEXICO...AND NET RESULT IS A DRY FORECAST. THE GFS/CANADIAN HAVE A MUCH STRONGER LOW LEVEL JET BECAUSE OF A STRONG SHORTWAVE...THUS SPREAD PRECIPITATION OVER THE ENTIRE AREA. THIS LATTER SCENARIO WOULD ALSO YIELD A SNOW TO SLEET TO FREEZING RAIN SITUATION. ONCE THE SHORTWAVE GOES BY...THE PRECIPITATION DIMINISH. SINCE ALL SCENARIOS SEEM PLAUSIBLE GIVEN THE MODELS HAVE MAINTAINED GOOD CONTINUITY...HAVE COMPROMISED. THIS RESULTS IN A SLIGHT LOWERING OF PRECIPITATION CHANCES FOR SUNDAY WHILE SUNDAY NIGHT WAS PRETTY SIMILAR. FOR PRECIPITATION TYPE...BOTH SNOW AND FREEZING RAIN SEEM EQUALLY LIKELY TO OCCUR...SINCE THERE ARE ALSO ISSUES WITH ICE IN THE CLOUDS. HOPEFULLY MODELS WILL COME TOGETHER SOON. THE TEMPERATURE FORECAST IS ALSO A COMPROMISE...BUT DECENT AGREEMENT EXISTS THAT READINGS SHOULD GET UP CLOSE TO FREEZING ON SUNDAY...THEN DROP VERY LITTLE SUNDAY NIGHT. .LONG TERM...MONDAY THROUGH THURSDAY NIGHT 325 AM CST FRI JAN 25 2013 25.00Z ECMWF/GFS/GFS ENSEMBLES ALL DEPICT A FAIRLY SIMILAR SCENARIO THROUGH THE LONG TERM PERIOD...WHILE THE 25.00Z CANADIAN IS AN OUTLIER. THE PERIOD STARTS OFF WITH TROUGHING OVER THE WESTERN U.S. WITH BROAD RIDGING DOWNSTREAM OVER THE EASTERN U.S.. MEANWHILE...A POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PRESENT OVER THE NORTHWEST TERRITORIES. THE CANADIAN IS THE ONLY MODEL THAT EJECTS OUT THE SOUTHERN PORTION OF THE WESTERN UPPER TROUGH AND PHASES IT WITH SOME NORTHERN STREAM ENERGY...RESULTING IN A POSSIBLE SNOWSTORM FOR THE AREA ON TUESDAY. THE REST OF THE MODELS SAY THERE IS NO PHASING...AND IN THE CASE OF THE ECMWF...THE SOUTHERN PORTION CUTS-OFF. WITH NO PHASING...MUCH OF MONDAY THROUGH TUESDAY ENDS UP DRY. HAVE MAINTAINED SOME LOW PRECIPITATION CHANCES DURING THIS TIME PERIOD...SINCE THE 25.00Z ECMWF AND GFS DO DEPICT A LITTLE LIGHT QPF FROM WEAK SHORTWAVES COMING THROUGH IN THE SOUTHWEST FLOW. AFTER TUESDAY...THE POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PROGGED TO DIVE DOWN INTO THE UPPER MIDWEST BY 12Z WEDNESDAY. THE AREA THEN GENERALLY REMAINS UNDER TROUGHING THROUGH THURSDAY NIGHT. AS SUCH...850MB AND 925MB TEMPS TAKE A NOSE-DIVE. LATEST 25.00Z ECMWF KEEPS 850MB TEMPS BELOW -20C AFTER 18Z WEDNESDAY...A DECENT DROP FROM BEING UP BETWEEN 0 AND +4C AT 00Z TUESDAY. THUS BELOW NORMAL TEMPERATURES LOOK LIKELY. ANY PRECIPITATION SHOULD BE CONFINED TO BEFORE THE COLD AIR COMES IN...WITH ARCTIC HIGH PRESSURE DOMINATING AFTERWARDS. && .AVIATION...TODAY AND TONIGHT 535 AM CST FRI JAN 25 2013 LIGHT SNOW AND VSBY RESTRICTIONS HAVE MOVED OUT OF THE TAF SITES AS OF 11Z. BKN-OVC CLOUD DECKS IN THE 3500 TO 5K FT RANGE WILL GIVE WAY TO CLOUD DECKS IN THE 2K-3K FT RANGE LATER THIS MORNING AS SOME MOISTURE WRAPPING AROUND A NORTHERN MN LOW AND ASSOCIATED WITH THE TRAILING COLD FRONT SPREADS ACROSS THE AREA. MAY SEE A FEW FLURRIES FROM THESE CLOUDS TODAY...BUT LEFT THIS OUT OF THE TAFS FOR NOW WITH UPSTREAM OBS OVER CENTRAL/WEST-CENTRAL MN ALL 10SM AT THIS TIME. THE COLD FRONT WILL PASS THRU THE TAF SITES LATER THIS MORNING WITH WINDS BECOMING NORTHWEST AND INCREASING INTO THE 14-20KT G23-30KTS FOR THE AFTERNOON. WITH RATHER FAST MOVING SYSTEMS...THE CLOUDS ALREADY LOOK TO SCATTER OUT/DECREASE LATE THIS AFTERNOON/EARLY THIS EVENING...WITH SKIES BECOMING CLEAR FOR THE LATE EVENING AND OVERNIGHT HOURS. WINDS WILL DIMINISH RATHER QUICKLY THIS EVENING AS WELL WITH THE CENTER OF THE NEXT CANADIAN HIGH EXPECTED TO BE CENTERED NEAR THE MS RIVER BY 12Z SAT. && .ARX WATCHES/WARNINGS/ADVISORIES... 519 AM CST FRI JAN 25 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
519 AM CST FRI JAN 25 2013 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 325 AM CST FRI JAN 25 2013 MAIN FORECAST CONCERNS ARE ON SNOW AND WIND POTENTIAL TODAY...THEN IF PRECIPITATION CAN OCCUR AND WHAT TYPE FOR SUNDAY INTO SUNDAY NIGHT. CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT TROUGH OFF THE PACIFIC NORTHWEST COAST...RIDGING OVER THE NORTHERN U.S. ROCKIES INTO ALBERTA...A SHORTWAVE TROUGH DIGGING INTO NORTHWEST MINNESOTA...AND A SHORTWAVE OVER SOUTHEAST MINNESOTA. AHEAD OF THIS LATTER SHORTWAVE...WATER VAPOR...IR IMAGERY AND SURFACE OBSERVATIONS SHOWED A LARGE EXPANSE OF MID AND HIGH CLOUDS. RAP TROPOPAUSE ANALYSIS ALSO HAD A BROAD 120-140KT JET FROM NEBRASKA TO OHIO DOWNSTREAM OF THE SHORTWAVE...ACTUALLY PLACING THE FORECAST AREA IN THE SUBSIDENT LEFT ENTRANCE REGION. 00Z SOUNDINGS FROM MPX...GRB AND DVN SHOWED A GREAT DEAL OF DRY AIR BELOW 700MB...WITH DEWPOINT DEPRESSIONS AS MUCH AS 30C. THIS DRY AIR HAS BEEN EFFECTIVE AT MINIMIZING SNOWFALL OUT OF THE MID/HIGH CLOUDS FROM REACHING THE SURFACE. THERE WAS HIGHER LOWER LEVEL MOISTURE OFF TO THE WEST AT ABR AND OAX...NOTED BY ITS 00Z SOUNDING HAVING 850MB DEWPOINT DEPRESSION BETWEEN 1-5C. THIS HAS BEEN SLOWLY ADVECTING TOWARDS THE AREA REFLECTED BY SOUTHWEST 25-40KT WINDS ON PROFILER AND VWP DATA. BETWEEN 06-08Z...SOME SNOW FINALLY GOT GOING...BUT THE BACK EDGE BEHIND THE LEAD SHORTWAVE WAS RAPIDLY PUSHING EAST...WITH KRST AND KCCY NOW DRY. TO THE NORTH...A BAND OF WARM ADVECTION SNOW HAS BEEN ONGOING FROM NORTHERN MN INTO NORTHERN WI...DOWNSTREAM OF THE NORTHWEST MN SHORTWAVE TROUGH. IN THE WAKE OF THIS SHORTWAVE TROUGH...ANOTHER SURGE OF ARCTIC AIR WAS NOTED WITH TEMPERATURES IN THE TEENS AND 20S BELOW ZERO OVER CENTRAL SASKATCHEWAN. THE COLD AIR WAS IN THE WAKE OF A 1012MB SURFACE LOW IN NORTHWEST MN. TODAY AND TONIGHT...MODELS ARE IN GOOD AGREEMENT DROPPING THE SHORTWAVE TROUGH OVER NORTHWEST MINNESOTA ACROSS CENTRAL WISCONSIN BY 18Z...THEN INTO SOUTHEAST LOWER MI BY 00Z. 500MB HEIGHTS SLOWLY RISE THEREAFTER AS THE NORTHERN ROCKIES RIDGE SLIDES EASTWARD... PLACING THE FORECAST AREA IN AN INFLECTION POINT BETWEEN A TROUGH AND RIDGE AXIS BY 12Z SATURDAY. THE TROPOPAUSE DROPS NICELY THIS MORNING WITH THE SHORTWAVE TROUGH MOVING IN...AS MUCH AS 100MB TO NEAR 350MB ACROSS MUCH OF WISCONSIN BY 15Z. ALTHOUGH THIS IS GOOD DYNAMIC FORCING...THE SCOURING OUT OF MID AND UPPER LEVEL MOISTURE BY THE LEAD SHORTWAVE AHEAD OF THE TROUGH IS VERY PROBLEMATIC. AS SUCH...MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION WITH THE WARM ADVECTION AND DPVA AHEAD OF THE SYSTEM. THIS MATCHES TOO WITH RADAR TRENDS...AND THUS HAVE SHORTENED THE END TIME OF THE ADVISORY TO 12Z. IN FACT...WE MAY HAVE TO WAIT UNTIL THE AFTERNOON...WHEN SNOW ACTUALLY LOOKS BETTER IN THE WAKE OF THE SHORTWAVE TROUGH AND SURFACE LOW. THIS IS DUE TO COLD ADVECTION COMBINING WITH LINGERING SURFACE MOISTURE TO PRODUCE CONVECTIVE SNOW. THE 25.00Z NAM AND HIRES NMM RUNS ARE THE MOST BULLISH WITH THE CONVECTIVE IDEA...WHILE ARW MODELS ARE NOT. IT APPEARS THE NMM CORE MAY BE MOISTENING SURFACE DEWPOINTS UP TOO MUCH. TOOK A COMPROMISE APPROACH WHICH RESULTS IN FLURRIES ALONG THE MS RIVER AND SCATTERED SNOW SHOWERS NORTH OF I-94 WHERE THE BEST LOW LEVEL INSTABILITY IS PRESENT. IN ADDITION TO THE SNOW...SETUP FOR THE AFTERNOON IS FAVORABLE FOR WINDY CONDITIONS. THE COMBINATION OF COLD ADVECTION...A TIGHT PRESSURE GRADIENT IN THE WAKE OF THE LOW...BEING AT PEAK HEATING AND MIXING DEPTHS UP TO 875-900MB SHOULD YIELD GUSTS IN THE 25-30 KT RANGE. EXPECT THE SNOW TO QUICKLY DIMINISH THIS EVENING WITH LOSS OF HEATING AND THE SHORTWAVE TROUGH SHIFTING OFF. WINDS LOOK TO TAKE SOME TIME DIMINISHING SINCE THE HIGH PRESSURE AREA DOES NOT BUILD IN UNTIL LATE IN THE NIGHT...I.E. AT THE TIME OF THE INFLECTION POINT IN THE FLOW AT 500MB. THE COMBINATION OF WIND AND MUCH OF THE AREA STILL WITH NEAR BARE GROUND WILL KEEP LOWS WARMER...ESPECIALLY COMPARED TO THE NAM WHICH HAS 5 INCHES ON THE GROUND ACROSS THE FORECAST AREA. LEANED CLOSER TO THE ECMWF AND MAV GUIDANCE FOR LOWS. SATURDAY AND SATURDAY NIGHT...THE UPPER RIDGING OVER THE NORTHERN ROCKIES IS PROGGED TO CONTINUE MARCHING EAST TOWARDS THE FORECAST AREA DURING THIS TIME PERIOD...PUSHED ALONG BY TROUGHING OFF THE PACIFIC NORTHWEST MOVING INLAND AS WELL AS AN UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING INTO SOUTHEAST COLORADO. THE SHIFT EAST OF THE UPPER RIDGE AXIS...REACHING EASTERN MN BY 12Z SUNDAY...WILL SETUP A LOW LEVEL RETURN FLOW OVER THE FORECAST AREA FOR THE AFTERNOON AND NIGHT. AN INCREASE OF MID/HIGH CLOUDS IS LIKELY GIVEN THE WARM ADVECTION PATTERN...NOTED TOO BY 925MB TEMPS CLIMBING FROM AROUND -12C AT 12Z SATURDAY TO -2 TO -6C BY 12Z SUNDAY. THE QUESTION MARK IS LATE SATURDAY NIGHT...IF THE LOW LEVEL MOISTURE WILL BE DEEP ENOUGH TO RESULT IN PRECIPITATION. THE 25.00Z NAM/CANADIAN SUGGESTS THIS WOULD OCCUR FROM THE KANSAS CITY AREA INTO NORTHEAST IOWA. COMPARED TO THE 25.00Z GFS/ECMWF/UKMET... THIS SEEMS A LITTLE TOO FAR NORTH / FAST. THE OTHER MODEL GROUP KEEPS THE BULK OF THE WARM ADVECTION PRECIPITATION SOUTH OF I-80. THUS...HAVE KEPT THE ENTIRE PERIOD FROM 12Z SATURDAY TO 12Z SUNDAY DRY. WITH THE WARMING 925MB TEMPS AND SOME SUN...HIGHS SHOULD BOUNCE BACK INTO THE TEENS FOR SATURDAY. WARM ADVECTION PERSISTING THROUGH THE NIGHT PLUS CLOUDS AROUND WILL LEAD TO RISING TEMPERATURES SATURDAY NIGHT. SUNDAY AND SUNDAY NIGHT...THIS PERIOD REMAINS VERY PROBLEMATIC AND UNCERTAIN. THE MAIN PROBLEM IS THE STRENGTH AND SPEED OF THE UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING UP TOWARDS THE AREA ON SUNDAY. THE SPREAD RANGES FROM: 1. A RELATIVELY STRONG 25.00Z GFS/CANADIAN...STILL SHOWING AT LEAST A POTENT SHORTWAVE COMING THROUGH THE FORECAST AREA AROUND 06Z MONDAY. 2. A REALLY WEAK 24.12Z/25.00Z ECMWF WHICH SHEAR THE UPPER LOW APART AND HAVE ITS REMNANTS TRACK ALONG I-80. THE 25.00Z NAM/UKMET LIE IN-BETWEEN THESE SCENARIOS. THE DIFFERENCES NOT ONLY IMPACT WHETHER IT WILL PRECIPITATE...BUT ALSO WHAT TYPE WOULD OCCUR IF IT DOES PRECIPITATE. THE ECMWF...BEING THE WEAKEST...LIMITS THE AMOUNT OF MOISTURE RETURN INTO THE FORECAST AREA FROM THE GULF OF MEXICO...AND NET RESULT IS A DRY FORECAST. THE GFS/CANADIAN HAVE A MUCH STRONGER LOW LEVEL JET BECAUSE OF A STRONG SHORTWAVE...THUS SPREAD PRECIPITATION OVER THE ENTIRE AREA. THIS LATTER SCENARIO WOULD ALSO YIELD A SNOW TO SLEET TO FREEZING RAIN SITUATION. ONCE THE SHORTWAVE GOES BY...THE PRECIPITATION DIMINISH. SINCE ALL SCENARIOS SEEM PLAUSIBLE GIVEN THE MODELS HAVE MAINTAINED GOOD CONTINUITY...HAVE COMPROMISED. THIS RESULTS IN A SLIGHT LOWERING OF PRECIPITATION CHANCES FOR SUNDAY WHILE SUNDAY NIGHT WAS PRETTY SIMILAR. FOR PRECIPITATION TYPE...BOTH SNOW AND FREEZING RAIN SEEM EQUALLY LIKELY TO OCCUR...SINCE THERE ARE ALSO ISSUES WITH ICE IN THE CLOUDS. HOPEFULLY MODELS WILL COME TOGETHER SOON. THE TEMPERATURE FORECAST IS ALSO A COMPROMISE...BUT DECENT AGREEMENT EXISTS THAT READINGS SHOULD GET UP CLOSE TO FREEZING ON SUNDAY...THEN DROP VERY LITTLE SUNDAY NIGHT. .LONG TERM...MONDAY THROUGH THURSDAY NIGHT 325 AM CST FRI JAN 25 2013 25.00Z ECMWF/GFS/GFS ENSEMBLES ALL DEPICT A FAIRLY SIMILAR SCENARIO THROUGH THE LONG TERM PERIOD...WHILE THE 25.00Z CANADIAN IS AN OUTLIER. THE PERIOD STARTS OFF WITH TROUGHING OVER THE WESTERN U.S. WITH BROAD RIDGING DOWNSTREAM OVER THE EASTERN U.S.. MEANWHILE...A POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PRESENT OVER THE NORTHWEST TERRITORIES. THE CANADIAN IS THE ONLY MODEL THAT EJECTS OUT THE SOUTHERN PORTION OF THE WESTERN UPPER TROUGH AND PHASES IT WITH SOME NORTHERN STREAM ENERGY...RESULTING IN A POSSIBLE SNOWSTORM FOR THE AREA ON TUESDAY. THE REST OF THE MODELS SAY THERE IS NO PHASING...AND IN THE CASE OF THE ECMWF...THE SOUTHERN PORTION CUTS-OFF. WITH NO PHASING...MUCH OF MONDAY THROUGH TUESDAY ENDS UP DRY. HAVE MAINTAINED SOME LOW PRECIPITATION CHANCES DURING THIS TIME PERIOD...SINCE THE 25.00Z ECMWF AND GFS DO DEPICT A LITTLE LIGHT QPF FROM WEAK SHORTWAVES COMING THROUGH IN THE SOUTHWEST FLOW. AFTER TUESDAY...THE POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PROGGED TO DIVE DOWN INTO THE UPPER MIDWEST BY 12Z WEDNESDAY. THE AREA THEN GENERALLY REMAINS UNDER TROUGHING THROUGH THURSDAY NIGHT. AS SUCH...850MB AND 925MB TEMPS TAKE A NOSE-DIVE. LATEST 25.00Z ECMWF KEEPS 850MB TEMPS BELOW -20C AFTER 18Z WEDNESDAY...A DECENT DROP FROM BEING UP BETWEEN 0 AND +4C AT 00Z TUESDAY. THUS BELOW NORMAL TEMPERATURES LOOK LIKELY. ANY PRECIPITATION SHOULD BE CONFINED TO BEFORE THE COLD AIR COMES IN...WITH ARCTIC HIGH PRESSURE DOMINATING AFTERWARDS. && .AVIATION... 1111 AM CST THU JAN 24 2013 TIMING/CIGS/VSBYS REMAIN PROBLEMATIC WITH ASSOCIATED CLOUDS/EXPECTED SNOW WITH SHORTWAVE TROUGH MOVING ACROSS THE REGION. CIGS HAVE STARTED TO LOWER ACROSS THE REGION OVER THE LAST COUPLE HOURS...WITH MORE RETURNS SHOWING UP ON RADAR...BUT NOT MUCH IN THE WAY OF -SN REACHING THE SFC. RAP13/NAM12 CONTINUE TO SUGGEST RAPID SATURATION OF THE DRY LOW LEVELS OVER THE NEXT FEW HOURS...WITH CIGS FOLLOWING SUIT AND SOME -SN. NAM12 BUFKIT SOUNDINGS CAPTURED THE NEAR SFC DRY LAYER THE BEST...COMPARED TO THE DVN 00Z SOUNDING...SO USING ITS BUFKIT SOUNDINGS TO AID IN TIMING OF LOWER CIGS/-SN. STILL THINK A DECENT CHANCE FOR SOME MVFR CIGS EARLY THIS MORNING...ALTHOUGH NOT SOLD ON SUB 3SM -SN ANYMORE. SNOW ACCUMS LOOK MINOR...LESS THAN 1/2 AT KRST AND LESS THAN 1 INCH AT KLSE. IT WILL BE FLUFFY LOW WATER CONTENT SNOW...SO IT WILL MOVE AROUND EASILY. DON/T EXPECT AN IMPACT ON VSBYS UNLESS A FEW INCHES WOULD FALL. BY LATE MORNING...A SFC COLD FRONT WILL BE SWEEPING THROUGH...WITH COLD AIR ADVECTION AND SHARP LOW LEVEL LAPSE RATES BEHIND IT. THIS COULD BRING A BETTER CHANCE FOR 2500 FT CIGS ALONG WITH SCT -SHSN. ANY -SHSN COULD REDUCE VSBYS TO 2-3SM FOR A SHORT PERIOD...BUT NOT ABLE TO TIME SO WILL LEAVE P6SM FOR NOW. IN ADDITION...EXPECT BLUSTERY WINDS AS THEY TURN NORTHWEST BEHIND THE FRONT. THESE SHOULD DIMINISH WITH NIGHT FALL AS HIGH PRESSURE STARTS TO BUILD IN FROM THE PLAINS. LOOK FOR CLEARING SKIES ALSO...ALONG WITH AN END TO ANY LINGERING -SHSN. && .ARX WATCHES/WARNINGS/ADVISORIES... 519 AM CST FRI JAN 25 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 AM CST FRI JAN 25 2013 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 325 AM CST FRI JAN 25 2013 MAIN FORECAST CONCERNS ARE ON SNOW AND WIND POTENTIAL TODAY...THEN IF PRECIPITATION CAN OCCUR AND WHAT TYPE FOR SUNDAY INTO SUNDAY NIGHT. CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT TROUGH OFF THE PACIFIC NORTHWEST COAST...RIDGING OVER THE NORTHERN U.S. ROCKIES INTO ALBERTA...A SHORTWAVE TROUGH DIGGING INTO NORTHWEST MINNESOTA...AND A SHORTWAVE OVER SOUTHEAST MINNESOTA. AHEAD OF THIS LATTER SHORTWAVE...WATER VAPOR...IR IMAGERY AND SURFACE OBSERVATIONS SHOWED A LARGE EXPANSE OF MID AND HIGH CLOUDS. RAP TROPOPAUSE ANALYSIS ALSO HAD A BROAD 120-140KT JET FROM NEBRASKA TO OHIO DOWNSTREAM OF THE SHORTWAVE...ACTUALLY PLACING THE FORECAST AREA IN THE SUBSIDENT LEFT ENTRANCE REGION. 00Z SOUNDINGS FROM MPX...GRB AND DVN SHOWED A GREAT DEAL OF DRY AIR BELOW 700MB...WITH DEWPOINT DEPRESSIONS AS MUCH AS 30C. THIS DRY AIR HAS BEEN EFFECTIVE AT MINIMIZING SNOWFALL OUT OF THE MID/HIGH CLOUDS FROM REACHING THE SURFACE. THERE WAS HIGHER LOWER LEVEL MOISTURE OFF TO THE WEST AT ABR AND OAX...NOTED BY ITS 00Z SOUNDING HAVING 850MB DEWPOINT DEPRESSION BETWEEN 1-5C. THIS HAS BEEN SLOWLY ADVECTING TOWARDS THE AREA REFLECTED BY SOUTHWEST 25-40KT WINDS ON PROFILER AND VWP DATA. BETWEEN 06-08Z...SOME SNOW FINALLY GOT GOING...BUT THE BACK EDGE BEHIND THE LEAD SHORTWAVE WAS RAPIDLY PUSHING EAST...WITH KRST AND KCCY NOW DRY. TO THE NORTH...A BAND OF WARM ADVECTION SNOW HAS BEEN ONGOING FROM NORTHERN MN INTO NORTHERN WI...DOWNSTREAM OF THE NORTHWEST MN SHORTWAVE TROUGH. IN THE WAKE OF THIS SHORTWAVE TROUGH...ANOTHER SURGE OF ARCTIC AIR WAS NOTED WITH TEMPERATURES IN THE TEENS AND 20S BELOW ZERO OVER CENTRAL SASKATCHEWAN. THE COLD AIR WAS IN THE WAKE OF A 1012MB SURFACE LOW IN NORTHWEST MN. TODAY AND TONIGHT...MODELS ARE IN GOOD AGREEMENT DROPPING THE SHORTWAVE TROUGH OVER NORTHWEST MINNESOTA ACROSS CENTRAL WISCONSIN BY 18Z...THEN INTO SOUTHEAST LOWER MI BY 00Z. 500MB HEIGHTS SLOWLY RISE THEREAFTER AS THE NORTHERN ROCKIES RIDGE SLIDES EASTWARD... PLACING THE FORECAST AREA IN AN INFLECTION POINT BETWEEN A TROUGH AND RIDGE AXIS BY 12Z SATURDAY. THE TROPOPAUSE DROPS NICELY THIS MORNING WITH THE SHORTWAVE TROUGH MOVING IN...AS MUCH AS 100MB TO NEAR 350MB ACROSS MUCH OF WISCONSIN BY 15Z. ALTHOUGH THIS IS GOOD DYNAMIC FORCING...THE SCOURING OUT OF MID AND UPPER LEVEL MOISTURE BY THE LEAD SHORTWAVE AHEAD OF THE TROUGH IS VERY PROBLEMATIC. AS SUCH...MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION WITH THE WARM ADVECTION AND DPVA AHEAD OF THE SYSTEM. THIS MATCHES TOO WITH RADAR TRENDS...AND THUS HAVE SHORTENED THE END TIME OF THE ADVISORY TO 12Z. IN FACT...WE MAY HAVE TO WAIT UNTIL THE AFTERNOON...WHEN SNOW ACTUALLY LOOKS BETTER IN THE WAKE OF THE SHORTWAVE TROUGH AND SURFACE LOW. THIS IS DUE TO COLD ADVECTION COMBINING WITH LINGERING SURFACE MOISTURE TO PRODUCE CONVECTIVE SNOW. THE 25.00Z NAM AND HIRES NMM RUNS ARE THE MOST BULLISH WITH THE CONVECTIVE IDEA...WHILE ARW MODELS ARE NOT. IT APPEARS THE NMM CORE MAY BE MOISTENING SURFACE DEWPOINTS UP TOO MUCH. TOOK A COMPROMISE APPROACH WHICH RESULTS IN FLURRIES ALONG THE MS RIVER AND SCATTERED SNOW SHOWERS NORTH OF I-94 WHERE THE BEST LOW LEVEL INSTABILITY IS PRESENT. IN ADDITION TO THE SNOW...SETUP FOR THE AFTERNOON IS FAVORABLE FOR WINDY CONDITIONS. THE COMBINATION OF COLD ADVECTION...A TIGHT PRESSURE GRADIENT IN THE WAKE OF THE LOW...BEING AT PEAK HEATING AND MIXING DEPTHS UP TO 875-900MB SHOULD YIELD GUSTS IN THE 25-30 KT RANGE. EXPECT THE SNOW TO QUICKLY DIMINISH THIS EVENING WITH LOSS OF HEATING AND THE SHORTWAVE TROUGH SHIFTING OFF. WINDS LOOK TO TAKE SOME TIME DIMINISHING SINCE THE HIGH PRESSURE AREA DOES NOT BUILD IN UNTIL LATE IN THE NIGHT...I.E. AT THE TIME OF THE INFLECTION POINT IN THE FLOW AT 500MB. THE COMBINATION OF WIND AND MUCH OF THE AREA STILL WITH NEAR BARE GROUND WILL KEEP LOWS WARMER...ESPECIALLY COMPARED TO THE NAM WHICH HAS 5 INCHES ON THE GROUND ACROSS THE FORECAST AREA. LEANED CLOSER TO THE ECMWF AND MAV GUIDANCE FOR LOWS. SATURDAY AND SATURDAY NIGHT...THE UPPER RIDGING OVER THE NORTHERN ROCKIES IS PROGGED TO CONTINUE MARCHING EAST TOWARDS THE FORECAST AREA DURING THIS TIME PERIOD...PUSHED ALONG BY TROUGHING OFF THE PACIFIC NORTHWEST MOVING INLAND AS WELL AS AN UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING INTO SOUTHEAST COLORADO. THE SHIFT EAST OF THE UPPER RIDGE AXIS...REACHING EASTERN MN BY 12Z SUNDAY...WILL SETUP A LOW LEVEL RETURN FLOW OVER THE FORECAST AREA FOR THE AFTERNOON AND NIGHT. AN INCREASE OF MID/HIGH CLOUDS IS LIKELY GIVEN THE WARM ADVECTION PATTERN...NOTED TOO BY 925MB TEMPS CLIMBING FROM AROUND -12C AT 12Z SATURDAY TO -2 TO -6C BY 12Z SUNDAY. THE QUESTION MARK IS LATE SATURDAY NIGHT...IF THE LOW LEVEL MOISTURE WILL BE DEEP ENOUGH TO RESULT IN PRECIPITATION. THE 25.00Z NAM/CANADIAN SUGGESTS THIS WOULD OCCUR FROM THE KANSAS CITY AREA INTO NORTHEAST IOWA. COMPARED TO THE 25.00Z GFS/ECMWF/UKMET... THIS SEEMS A LITTLE TOO FAR NORTH / FAST. THE OTHER MODEL GROUP KEEPS THE BULK OF THE WARM ADVECTION PRECIPITATION SOUTH OF I-80. THUS...HAVE KEPT THE ENTIRE PERIOD FROM 12Z SATURDAY TO 12Z SUNDAY DRY. WITH THE WARMING 925MB TEMPS AND SOME SUN...HIGHS SHOULD BOUNCE BACK INTO THE TEENS FOR SATURDAY. WARM ADVECTION PERSISTING THROUGH THE NIGHT PLUS CLOUDS AROUND WILL LEAD TO RISING TEMPERATURES SATURDAY NIGHT. SUNDAY AND SUNDAY NIGHT...THIS PERIOD REMAINS VERY PROBLEMATIC AND UNCERTAIN. THE MAIN PROBLEM IS THE STRENGTH AND SPEED OF THE UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING UP TOWARDS THE AREA ON SUNDAY. THE SPREAD RANGES FROM: 1. A RELATIVELY STRONG 25.00Z GFS/CANADIAN...STILL SHOWING AT LEAST A POTENT SHORTWAVE COMING THROUGH THE FORECAST AREA AROUND 06Z MONDAY. 2. A REALLY WEAK 24.12Z/25.00Z ECMWF WHICH SHEAR THE UPPER LOW APART AND HAVE ITS REMNANTS TRACK ALONG I-80. THE 25.00Z NAM/UKMET LIE IN-BETWEEN THESE SCENARIOS. THE DIFFERENCES NOT ONLY IMPACT WHETHER IT WILL PRECIPITATE...BUT ALSO WHAT TYPE WOULD OCCUR IF IT DOES PRECIPITATE. THE ECMWF...BEING THE WEAKEST...LIMITS THE AMOUNT OF MOISTURE RETURN INTO THE FORECAST AREA FROM THE GULF OF MEXICO...AND NET RESULT IS A DRY FORECAST. THE GFS/CANADIAN HAVE A MUCH STRONGER LOW LEVEL JET BECAUSE OF A STRONG SHORTWAVE...THUS SPREAD PRECIPITATION OVER THE ENTIRE AREA. THIS LATTER SCENARIO WOULD ALSO YIELD A SNOW TO SLEET TO FREEZING RAIN SITUATION. ONCE THE SHORTWAVE GOES BY...THE PRECIPITATION DIMINISH. SINCE ALL SCENARIOS SEEM PLAUSIBLE GIVEN THE MODELS HAVE MAINTAINED GOOD CONTINUITY...HAVE COMPROMISED. THIS RESULTS IN A SLIGHT LOWERING OF PRECIPITATION CHANCES FOR SUNDAY WHILE SUNDAY NIGHT WAS PRETTY SIMILAR. FOR PRECIPITATION TYPE...BOTH SNOW AND FREEZING RAIN SEEM EQUALLY LIKELY TO OCCUR...SINCE THERE ARE ALSO ISSUES WITH ICE IN THE CLOUDS. HOPEFULLY MODELS WILL COME TOGETHER SOON. THE TEMPERATURE FORECAST IS ALSO A COMPROMISE...BUT DECENT AGREEMENT EXISTS THAT READINGS SHOULD GET UP CLOSE TO FREEZING ON SUNDAY...THEN DROP VERY LITTLE SUNDAY NIGHT. .LONG TERM...MONDAY THROUGH THURSDAY NIGHT 325 AM CST FRI JAN 25 2013 25.00Z ECMWF/GFS/GFS ENSEMBLES ALL DEPICT A FAIRLY SIMILAR SCENARIO THROUGH THE LONG TERM PERIOD...WHILE THE 25.00Z CANADIAN IS AN OUTLIER. THE PERIOD STARTS OFF WITH TROUGHING OVER THE WESTERN U.S. WITH BROAD RIDGING DOWNSTREAM OVER THE EASTERN U.S.. MEANWHILE...A POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PRESENT OVER THE NORTHWEST TERRITORIES. THE CANADIAN IS THE ONLY MODEL THAT EJECTS OUT THE SOUTHERN PORTION OF THE WESTERN UPPER TROUGH AND PHASES IT WITH SOME NORTHERN STREAM ENERGY...RESULTING IN A POSSIBLE SNOWSTORM FOR THE AREA ON TUESDAY. THE REST OF THE MODELS SAY THERE IS NO PHASING...AND IN THE CASE OF THE ECMWF...THE SOUTHERN PORTION CUTS-OFF. WITH NO PHASING...MUCH OF MONDAY THROUGH TUESDAY ENDS UP DRY. HAVE MAINTAINED SOME LOW PRECIPITATION CHANCES DURING THIS TIME PERIOD...SINCE THE 25.00Z ECMWF AND GFS DO DEPICT A LITTLE LIGHT QPF FROM WEAK SHORTWAVES COMING THROUGH IN THE SOUTHWEST FLOW. AFTER TUESDAY...THE POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PROGGED TO DIVE DOWN INTO THE UPPER MIDWEST BY 12Z WEDNESDAY. THE AREA THEN GENERALLY REMAINS UNDER TROUGHING THROUGH THURSDAY NIGHT. AS SUCH...850MB AND 925MB TEMPS TAKE A NOSE-DIVE. LATEST 25.00Z ECMWF KEEPS 850MB TEMPS BELOW -20C AFTER 18Z WEDNESDAY...A DECENT DROP FROM BEING UP BETWEEN 0 AND +4C AT 00Z TUESDAY. THUS BELOW NORMAL TEMPERATURES LOOK LIKELY. ANY PRECIPITATION SHOULD BE CONFINED TO BEFORE THE COLD AIR COMES IN...WITH ARCTIC HIGH PRESSURE DOMINATING AFTERWARDS. && .AVIATION... 1111 AM CST THU JAN 24 2013 TIMING/CIGS/VSBYS REMAIN PROBLEMATIC WITH ASSOCIATED CLOUDS/EXPECTED SNOW WITH SHORTWAVE TROUGH MOVING ACROSS THE REGION. CIGS HAVE STARTED TO LOWER ACROSS THE REGION OVER THE LAST COUPLE HOURS...WITH MORE RETURNS SHOWING UP ON RADAR...BUT NOT MUCH IN THE WAY OF -SN REACHING THE SFC. RAP13/NAM12 CONTINUE TO SUGGEST RAPID SATURATION OF THE DRY LOW LEVELS OVER THE NEXT FEW HOURS...WITH CIGS FOLLOWING SUIT AND SOME -SN. NAM12 BUFKIT SOUNDINGS CAPTURED THE NEAR SFC DRY LAYER THE BEST...COMPARED TO THE DVN 00Z SOUNDING...SO USING ITS BUFKIT SOUNDINGS TO AID IN TIMING OF LOWER CIGS/-SN. STILL THINK A DECENT CHANCE FOR SOME MVFR CIGS EARLY THIS MORNING...ALTHOUGH NOT SOLD ON SUB 3SM -SN ANYMORE. SNOW ACCUMS LOOK MINOR...LESS THAN 1/2 AT KRST AND LESS THAN 1 INCH AT KLSE. IT WILL BE FLUFFY LOW WATER CONTENT SNOW...SO IT WILL MOVE AROUND EASILY. DON/T EXPECT AN IMPACT ON VSBYS UNLESS A FEW INCHES WOULD FALL. BY LATE MORNING...A SFC COLD FRONT WILL BE SWEEPING THROUGH...WITH COLD AIR ADVECTION AND SHARP LOW LEVEL LAPSE RATES BEHIND IT. THIS COULD BRING A BETTER CHANCE FOR 2500 FT CIGS ALONG WITH SCT -SHSN. ANY -SHSN COULD REDUCE VSBYS TO 2-3SM FOR A SHORT PERIOD...BUT NOT ABLE TO TIME SO WILL LEAVE P6SM FOR NOW. IN ADDITION...EXPECT BLUSTERY WINDS AS THEY TURN NORTHWEST BEHIND THE FRONT. THESE SHOULD DIMINISH WITH NIGHT FALL AS HIGH PRESSURE STARTS TO BUILD IN FROM THE PLAINS. LOOK FOR CLEARING SKIES ALSO...ALONG WITH AN END TO ANY LINGERING -SHSN. && .ARX WATCHES/WARNINGS/ADVISORIES... 325 AM CST FRI JAN 25 2013 WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR WIZ017-029. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1142 PM CST THU JAN 24 2013 .UPDATE...NO CHANGE FROM PREVIOUS ISSUANCE AREA 00Z RAOBS SHOWING THE VERY DRY LAYER...DEW POINT DEPRESSIONS ON THE ORDER OF 30C IN THE 850-800MB LAYER...THAT HAVE BEEN PREVENTING MUCH IN THE WAY OF GROUND TRUTH BELOW THE 15 TO 20 DBZ RETURNS WITH THE INITIAL WAA ALL THE WAY BACK TO CENTRAL MN. SNOW REPORTS HAVE BEEN LIMITED TO NRN MN AND NW WI. LATEST 01Z RAP AND NEW 00Z NAM SHOW THE DRY LAYER AROUND 850 MB WILL BE TOUGH TO SATURATE OVER THE CWA UNTIL AFTER 09Z...WITH REDUCED QPF AMOUNTS. 23Z HRRR DOES NOT BRING ANY QPF INTO THE CWA FOR THIS EVENT. RAP AND NAM SOUNDINGS DO EVENTUALLY SATURATE. REDUCED QPF AND THUS SNOW AMOUNTS ACROSS THE CWA...BUT STILL WORRIED ABOUT HIGH SNOW TO LIQUID RATIOS WITH THE DEPTH OF OF THE SATURATED DENDRITIC GROWTH ZONE...WITH SPC PROBABILITY OF 200 MB OR MORE AROUND 90 PCT ACROSS THE FAR NORTH AND 50 PCT DOWN TO THE IL BORDER IN THE ERN CWA. THE DEEP DGZ IS BEING SHOWN ON RAP SOUNDINGS IN THE EAST WITH DECENT OMEGA...SO ONLY REDUCED THE AMOUNTS BY 1/2 INCH TO 1 INCH FOR NOW. AVIATION/06Z TAFS/... WITH DELAY IN ONSET OF SNOW PLAN ON KEEPING VFR CONDITIONS AT TAF SITES UNTIL 09Z AT KMSN AND 10Z-11Z EAST...THEN MVFR WITH EXPECTED START OF STEADY LIGHT SNOW. WILL KEEP THE PERIOD OF IFR VSBYS AT ERN SITES BETWEEN 15Z AND 18-19Z AS DEEP SNOW GROWTH ZONE COINCIDENT WITH LIFT BRINGS POTENTIAL OF HIGH SNOW TO LIQUID RATIOS. SNOW BEGINS TO TAPER OFF FROM WEST TO EAST AFTER 18Z...THOUGH MVFR CIGS AND VERY LIGHT SNOW OR FLURRIES WILL CONTINUE UNTIL THE COLD FRONT CLEARS THE CWA AROUND 00Z. SOUNDINGS ALSO SUPPORT WIND GUSTS OF 20 TO 25 KTS AT ERN SITES AND AROUND 20 KTS AT KMSN BY MID TO LATE MORNING...THEN DIMINISHING BEHIND THE FRONT EARLY IN THE EVENING. MARINE... KEPT START TIME TO SMALL CRAFT ADVISORY ...THOUGH A FEW GUSTS HAVE REACHED 24-25 KNOTS AT KENOSHA AND POINTS SOUTH...DO NOT EXPECT FREQUENT CRITERIA LEVEL GUSTS TO KICK IN UNTIL 09Z AND WILL BE MAINLY NORTH OF MILWAUKEE. NEXT SHIFT WILL HAVE TO MONITOR FOR EITHER TO EXTEND THE AREA TO BE COVERED BY THE ADVISORY...OR START EARLIER IF WINDS CLIMB. PREV DISCUSSION... /ISSUED 410 PM CST THU JAN 24 2013/ SHORT TERM... TONIGHT AND FRIDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH WILL SEE SOME LAKE EFFECT JUST BRUSH THE LAKE SHORE INTO THE EVENING. NOT REALLY EXPECTING MUCH MORE THAN FLURRIES. BIGGER ISSUE WILL BE WIDESPREAD SNOWFALL TONIGHT INTO FRIDAY. HIGH CONFIDENCE IN ACCUMULATING SNOW ACROSS THE FORECAST AREA. MAIN PROBLEMS ARE TIMING OF THE SNOW AND AMOUNTS. THE NAM AND GFS CONTINUE TO CHEW ON A LOT OF DRY AIR THIS EVENING INTO EARLY TONIGHT...WHILE THE ECMWF AND CANADIAN SATURATE A LOT FASTER. LEANED TOWARD THE SLOWER SOLUTIONS BASED ON SHORT TERM MESO MODELS LOOKING SIMILAR TO THE NAM. LIQUID TO SNOW RATIOS ARE THE OTHER ISSUE. SOUNDINGS ARE SHOWING A VERY DEEP DENDRITE GROWTH LAYER...AS DEEP AS 350 MB IN THE NORTH. WITH 1000-500 MB THICKNESS VALUES IN THE 520S AND AND TEMPERATURES IN THE TEENS...EXPECTING VERY HIGH SNOW RATIOS. TOOK THEM AS HIGH 25 TO 1 IN THE NORTH...BUT WOULD NOT BE SURPRISED IF THEY GET EVEN HIGHER. ENDED UP WITH SIMILAR STORM TOTAL SNOW AMOUNTS AS PREVIOUS FORECAST...RANGING FROM 1 TO 2 INCHES IN THE SOUTHWEST FORECAST AREA TO 3 TO 4 IN THE NORTHEAST. THOUGHT ABOUT A WINTER WEATHER ADVISORY IN THE NORTHEAST...BUT WINDS STAY UNDER CONTROL WHILE THE SNOW IS FALLING...AND AMOUNTS ARE GENERALLY BORDERLINE FOR AN ADVISORY. MAY CAUSE A FEW ISSUES FOR THE MORNING COMMUTE...ESPECIALLY IN THE EAST WHERE THE SNOW WILL HANG ON LATER INTO THE MORNING. WIDESPREAD SNOW WILL WIND DOWN TOMORROW MORNING...WITH SNOW SHOWERS POSSIBLY LINGERING INTO THE AFTERNOON...ESPECIALLY IN THE NORTHEAST. LOOKS LIKE HIGHS ACTUALLY BACK NEAR NORMAL TOMORROW. FRIDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM BRISK NWLY WINDS AND COLD ADVECTION IN THE WAKE OF LOW PRESSURE MOVING EAST ACROSS THE GREAT LAKES WILL RETURN AN ARCTIC AIRMASS TO THE REGION FOR FRI NT. STEEP LOW LEVEL LAPSE RATES IN THE EARLY EVENING COULD MAINTAIN FLURRIES OR LIGHT SNOW SHOWERS IN ERN WI BEFORE CLEARING ARRIVES LATER IN THE EVENING. A 1030 MB POLAR HIGH WILL PROGRESS EWD ACROSS SRN WI SAT INTO EARLY SAT EVENING WITH LARGE SCALE RIDGING OVER THE PLAINS IN RESP0NSE TO AN UPSTREAM UPPER TROUGH IN THE PACIFIC NW AND A SHORTWAVE TROUGH MOVING INTO THE DESERT SW. THE SHORTWAVE TROUGH OVER THE DESERT SW WILL THEN LIFT NEWD AND EITHER TRACK INTO SRN WI OR REMAIN JUST TO THE SOUTH. THE ASSOCIATED PRESSURE TROUGH/WARM FRONT WILL PRODUCE A GOOD BAND OF PCPN BUT MODELS DIFFER ON PLACEMENT OF IT...SOME KEEPING THE MAIN AREA TO THE SOUTH. KEPT POPS IN THE 40-60 PERCENT RANGE FOR NOW. EITHER WAY...PCPN TYPE LOOKS MIXY. THERE COULD BE A BRIEF PERIOD OF TOTAL COLUMN SATURATION LEADING TO SNOW BUT DRIER AIR ALOFT AND A WARM LAYER COULD THEN RESULT IN FREEZING RAIN...FREEZING DRIZZLE...AND SLEET. PUT IN LIGHT ICE AND SNOW ACCUMULATION INTO SUNDAY FCST. THIS WOULD CONTINUE SUN NT AND POSSIBLY LINGER INTO MONDAY ALTHOUGH TEMPS MAY WARM ABOVE FREEZING...MEANING RAIN FOR PCPN TYPE. TEMPS EXPECTED TO GRADUALLY WARM THROUGH THIS PERIOD WITH HIGHS ABOVE FREEZING FOR MONDAY. LONG TERM... TUESDAY THROUGH THURSDAY...FORECAST CONFIDENCE LOW TO MEDIUM MODELS DIFFER ON STRENGTH AND PLACEMENT OF CYCLOGENESIS FROM THE PLAINS NEWD INTO ONTARIO CANADA FOR MON NT THROUGH WED...THUS THE LOWER CONFIDENCE. GIVEN THE TRACK IS TO THE WEST AND NORTH STILL WENT MILD WITH CHANCES OF RAIN THROUGH TUE. A STRONG COLD FRONT WILL THEN SWEEP THROUGH THE STATE TUE NT WITH RAIN CHANGING TO SNOW. BRISK NWLY WINDS AND COLD ADVECTION WILL PREVAIL INTO WED WITH A POLAR AIRMASS RETURNING. HIGH PRESSURE TO THEN SETTLE OVER THE REGION ON THU WITH BELOW NORMAL TEMPS EXPECTED. AVIATION/00Z TAFS/... MID AND HIGH LEVEL CLOUDS WILL KEEP SKIES MAINLY OVERCAST THROUGH THE REMAINDER OF THE DAY. WILL CONTINUE TO SEE CIGS NEAR MVFR LATE THIS AFTERNOON IN THE SOUTHEAST AS LAKE EFFECT SNOW SHOWERS BRUSH THE LAKE SHORE. STILL NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION...IF ANYTHING AT ALL. OTHERWISE...DRY WEATHER AND VFR CONDITIONS WILL PREVAIL THROUGH THE EVENING HOURS. WILL SEE DETERIORATING CONDITIONS AFTER MIDNIGHT...AS WIDESPREAD SNOWFALL MOVES INTO THE AREA. MVFR CONDITIONS ARE LIKELY...WITH POSSIBLY LOWER VSBYS IN ANY AREAS OF MODERATE SNOWFALL. THE WIDESPREAD SNOWFALL WILL WIND DOWN FRIDAY MORNING...THOUGH COULD SEE A FEW SNOW SHOWERS LINGER INTO THE AFTERNOON. WILL LIKELY SEE MVFR CIGS LINGER THOUGH MUCH OF THE DAY TOMORROW. MARINE... WILL LET CURRENT SMALL CRAFT ADVISORY EXPIRE AT SCHEDULED 22Z TIME. LATEST WEBCAMS AND WAVE MODEL SHOW WAVES GENERALLY BELOW 4 FEET NOW. SOUTH WINDS WILL PICK UP TONIGHT...WITH WAVES LIKELY EXCEEDING 4 FEET NORTH OF PORT WASHINGTON. WILL THUS ISSUE ANOTHER SMALL CRAFT ADVISORY FOR LATE TONIGHT INTO FRIDAY AFTERNOON FOR THE NORTHERN MARINE ZONE. WINDS WILL BE CLOSE TO SMALL CRAFT ADVISORY ACROSS THE NEARSHORE WATERS LATER FRIDAY INTO FRIDAY NIGHT. SEEMS TOO BORDERLINE FOR AN ADVISORY AT THIS TIME THOUGH. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY FROM 3 AM TO 4 PM CST FRIDAY FOR LMZ643. && $$ UPDATE...REM TONIGHT/FRIDAY AND AVIATION/MARINE...DDV FRIDAY NIGHT THROUGH THURSDAY...GEHRING
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1031 PM CST THU JAN 24 2013 UPDATED FOR LATEST TRENDS AND TO ADD SECTION FOR 06Z TAFS .UPDATE...LEADING BAND OF ISENT LIFT SNOWS FINALLY GOT GOING BETWEEN 900 PM AND 1000 PM. BUT BAND WAS SWEEPING EWD...WITH NOT MUCH GOING ON BACK TO THE WEST. THINK REDEVELOPMENT WL OCCUR SOONER OVER THE N...SO WL PROBABLY JUST HAVE SOME PERIODS OF SNOW THERE. SHOULD BE A MORE DEFINED LULL IN THE SNOW ACRS C AND INTO E-C WI. MAIN UPR SYSTEM LOOKS PRETTY IMPRESSIVE ON STLT IMAGERY...AND COUNTING ON THAT GETTING BETTER SNOWS GOING LATE TNGT INTO FRI. SKOWRONSKI && .PREV DISCUSSION...ISSUED AT 834 PM CST THU JAN 24 2013... UPDATE...DRY AIR AT LOW-LEVELS REALLY PLAYING HAVOC WITH THIS FCST. 00Z RAOBS FM GRB/MPX STILL VERY DRY AT LOW-LEVELS. DVN AND ILX DRY TOO...INDICATING SLY FLOW WL CONT TO REINFORCE THE DRY AIR AS PCPN FALLING FM MID-DECK ABV TRIES TO SATURATE IT. DON/T HAVE A HIGH DEGREE OF CONFIDENCE IN HOW THIS WILL ALL ULTIMATELY PLAY OUT...BUT CURRENT FCST IS GOING TO NEED SOME ADJUSTMENTS. FIRST...GOING TO DELAY THE START OF THE ADVISORY FOR MANY AREAS. WL ALLOW THE FAR NW TO START AT 03Z AS PLANNED...BUT HOLD OFF ON THE REST OF THE N UNTIL AT LEAST 06Z. INITIAL SURGE OF ISENT LIFT PCPN MAY NOT COME TOGETHER UNTIL IT IS NE OF THE GRB/FOX CITIES AREA...SO WL DELAY ADVISORY FOR THESE AREAS UNTIL 09Z. ON THE FLIP SIDE...LAKE-EFFECT SNOW BAND CONTD TO BACK WWD TOWARD THE SHORE. BAND HAD SEVERAL EMBEDDED MESO-VORTICIES...AND RADAR RETURNS SUGGESTED SOME DECENT SNOWFALL RATES. PLUS...BAND COULD INTENSIFY WHEN IT STARTS TO GET SEEEDED FM ABV. SO...SINCE WE ARE GOING TO HAVE AN ADVISORY FOR THE LAKESHORE ANYWAY...WL MOVE THE START TIME OF THAT UP TO 03Z TO ACCOUNT FOR THE LAKE-EFFECT. EXPERIENCE HAS SHOWN THAT WHENEVER YOU NEED TO DELAY THE ONSET OF AN EVENT SUCH AS THIS...YOU ALMOST ALWAYS NEED TO CHOP SNOW TOTALS AS WELL. WITH ISENT LIFT PCPN NOW LOOKING LESS SIG...MUCH OF THE ACCUMULATION WL NEED TO COME FM UPR SHRTWV. VORT PROGGED TO TRACK SE ACRS THE FCST AREA...RIGHT TOWARD GRB TOMORROW AFTN. THAT SUGGESTS MAX SNOWS OVER NRN/NE WI. WL LEAVE TOTALS SIMILAR TO PREV FCST THERE...BUT CUT BACK FARTHER TO THE S AND W. UPDATED PRODUCT SUITE OUT ASAP. SKOWRONSKI DISCUSSION ISSUED AT 615 PM CST THU JAN 24 2013... UPDATE...DONT LIKE AT ALL THE WAY THE SITN IS EVOLVING THIS EVENING. LOW-LEVELS REMAIN VERY DRY...AND SLY FLOW AHEAD OF THE INCOMING SYSTEM WL CONT TO REINFORCE THE DRY AIR FM THE S. THAT COULD PLAY HAVOC WITH THE ONSET OF PCPN...THE TIMING OF THE ADVISORY...AND SNOW AMNTS. RAP PAINTING A MUCH DIFFERENT PICTURE THAN THE REST OF THE GUID. IT HAS BAND OF SNOW IN ISENT LIFT ZONE TRYING TO CONSOLIDATE AS IT WORKS ACRS THE FCST AREA THIS EVENING. BUT THEN THAT BAND PUSHES OFF TO THE E AFTER MIDNIGHT...WITH AT LEAST A SEVERAL HR LULL IN THE PCPN BEFORE LOW-LEVELS SATURATE AGAIN AND PCPN WITH THE UPR SHRTWV ARRIVES. IT/S RATHER HARD TO ARGUE WITH THAT IDEA GIVEN THE CURRENT RADAR TRENDS...AND THE VERY LIMITED NUMBER OF OB SITES REPORTING SNOW IN MN/NW WI EARLY THIS EVENING. NOT READY TO MAKE ANY SIG CHGS TO THE FCST YET... THOUGH THAT MAY BECOME NECESSARY IF CURRENT RADAR/OB TRENDS HOLD. ONE AREA THAT COULD SEE SNOW A LITTLE EARLIER THAN EXPECTED IS THE LAKESHORE RGN OF MTW COUNTY. MESOSCALE CIRCULATION WORKING NWD OVER WRN LAKE MICHIGAN COULD GET SOME SHSN AND FLURRIES INTO LAKESHORE AREAS DURING THE EVENING. GOING TO UPDATE THE FCST FOR THE LAKE-EFFECT NOW...BUT HOLD OFF MAKING ANY MORE SUBSTANTIAL CHGS FOR NOW. SKOWRONSKI DISCUSSION ISSUED AT 541 PM CST THU JAN 24 2013... SHORT TERM...TONIGHT AND FRIDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH PRESSURE CENTERED ACROSS THE STATE EARLY THIS AFTERNOON. MID AND HIGH CLOUDS ARE ALREADY ON THE INCREASE...HOWEVER...AHEAD OF THE NEXT SHORTWAVE TROUGH MOVING ESE OVER SOUTHERN SASKATCHEWAN. RADARS ARE PUSHING AN AREA OF LIGHT TO MODERATE SNOW OVER FAR NORTHERN NORTH DAKOTA AND SOUTHERN MANITOBA AND IS STARTING TO ENTER NORTHERN MINNESOTA. AS THE SHORTWAVE TRACKS TOWARDS THE REGION TONIGHT AND OVER THE REGION ON FRIDAY...SNOWFALL AMOUNTS AND HEADLINES ARE THE MAIN FORECAST CONCERNS. TONIGHT...SHORTWAVE TROUGH OVER THE SOUTHERN CANADIAN PRAIRIE WILL DIVE SOUTHEAST TONIGHT ON ITS WAY TO THE ARROWHEAD OF MINNESOTA BY 12Z FRIDAY. AHEAD OF THE SHORTWAVE...FORCING IN THE FORM OF DPVA AND ISENTROPIC ASCENT ON THE 280-285K SURFACES WILL SPREAD SOUTHEAST WHICH WILL LEAD TO A WARM ADVECTION BAND ENTERING NW WISCONSIN BY 00-03Z AND NORTH-CENTRAL AND NORTHEAST WISCONSIN IN THE 03-06Z TIME PERIOD. PLENTY OF UNCERTAINTY WITH THE DETAILS...INCLUDING WHERE AND WHEN THE BAND ENTERS THE FORECAST AREA...AND ALSO SNOWFALL RATIOS. THE LATEST SHORTER RANGE GUIDANCE INDICATES THAT A WARM ADVECTION SNOW BAND WILL DIVE SE INTO RHI-GRB LINE BETWEEN 03-06Z BEFORE WIDESPREAD SNOW ENTERS THE AREA AFTER MIDNIGHT. FGEN AND INSTABILITY ALOFT ARE NOT PARTICULARLY IMPRESSIVE...BUT MICROPHYSICS ARE A DIFFERENT STORY. BUFKIT SOUNDINGS FOR THE BOTH THE NAM/GFS INDICATE AN ISOTHERMAL LAYER FROM THE SURFACE TO ABOUT 575MB...FIRMLY IN THE DENDRITIC GROWTH ZONE. ASCENT WONT OCCUPY THIS ENTIRE LAYER...BUT SHOULD COINCIDE FOR ABOUT 200MB FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING. AS A RESULT...DESPITE MEDIOCRE FORCING AND INSTABILITY...SHOULDNT TAKE MUCH QPF IN ORDER TO GET A SUBSTANTIAL AMOUNT OF SNOW. ESTIMATING SNOWFALL RATIOS OF 20-30:1 WILL YIELD WIDESPREAD 2-4 INCH AMOUNTS BY MORNING FROM NORTH-CENTRAL WISCONSIN TO THE SOUTHERN FOX VALLEY. WILL ADD WAUPACA AND THE REST OF THE FOX VALLEY/LAKESHORE TO THE WINTER WEATHER ADVISORY SINCE THE SNOW WILL BE FLYING DURING THE MORNING RUSH HOURS WHERE 2-3 INCHES WILL PROBABLY ALREADY HAVE FALLEN. WILL ALSO BUMP UP THE START TIME OVER N-C WISCONSIN TO START IT AT 03Z. FRIDAY...THE SHORTWAVE WILL PASS ACROSS THE AREA DURING THE DAY...AND IT WILL PUSH A SURFACE LOW ACROSS NORTHERN WISCONSIN DURING THE AFTERNOON. FORCING WILL BE SHIFTING TO THE SOUTHEAST FRIDAY MORNING...WHICH MAY LEAD TO SOME DRY SLOTTING OVER CENTRAL AND EAST-CENTRAL WISCONSIN. BUT DEEPER COMMA HEAD MOISTURE DOES PASS OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN DURING THE DAY...WHERE HIGHER ACCUMS SHOULD RESIDE. WILL STILL HAVE THE VERY GOOD SNOW RATIOS FOR MUCH OF THE DAY...AND CAN SEE ADDITIONAL 1-2 INCHES OVER NORTHEAST HALF OF THE FORECAST AREA...AND LESS THAN AN INCH OVER THE SOUTHWEST. WINDS MAY START TO GET GUSTY LATE IN THE AFTERNOON...WHICH MAY LEAD TO MINOR BLOWING AND DRIFTING SNOW. HIGHS IN THE MID TEENS TO MID 20S. LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. CLIPPER SYSTEM WILL CONTINUE TO MOVE AWAY FROM THE AREA FRIDAY NIGHT. COULD BE A BRIEF PERIOD OF GUSTY WINDS AND BLOWING AND DRIFTING OF THE SNOW AS SYSTEM MOVES AWAY AND COLDER AIR FILTERS INTO THE REGION. WILL MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK... BUT WILL NOT HAVE IT IN THE GRIDS DUE TO THE BRIEF NATURE OF THE EVENT. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH MOST OF THE NIGHT ACROSS THE FAR NORTH. HAVE INCREASED POPS INTO THE CATEGORICAL RANGE FOR VILAS COUNTY AND INCREASED POPS OVER THE REMAINDER OF THE NORTH AS WELL. DID ADD A CHANCE OF FLURRIES THROUGH MOST OF THE NIGHT ACROSS THE SOUTH UNTIL CLEARING ARRIVES. DID SLOW THE ARRIVAL OF THE CLEARING BY SEVERAL HOURS...MAINLY DUE TO COLD NORTHERLY FLOW OFF THE WARMER WATERS OF LAKE SUPERIOR. MODELS DO SHOW DRYING OF THE 850MB MOISTURE TOWARDS 12Z ACROSS CENTRAL WISCONSIN. ON SATURDAY...DID LEAVE A FEW LINGERING FLURRIES FOR A FEW HOURS SATURDAY MORNING ACROSS THE FAR NORTH/NORTHEAST. WITH SUCH A COLD AIR MASS IN PLACE...ANY CUMULUS CLOUD COULD PRODUCE A FEW FLURRIES BEFORE DISSIPATING. NEW QUESTIONS ARISE FOR THE SATURDAY NIGHT PERIOD. LATEST WRF/CANADIAN NOW PRODUCE A FEW INCHES OF LIGHT SNOW ACROSS CENTRAL AND NORTHERN WISCONSIN...WHILE THE GFS/ECMWF DO NOT SHOW THIS FEATURE. WILL HAVE A SLIGHT CHANCE OF LIGHT SNOW ACROSS THE NORTH FOR NOW. CONFIDENCE REMAINS LOW THROUGHOUT THE REST OF THE FORECAST PERIOD WITH HANDLING OF SYSTEM SUNDAY NIGHT AND SUNDAY NIGHT...AND AGAIN TUESDAY. LATEST CANADIAN/ECMWF MODELS HAVE SHIFTED SYSTEM SUNDAY/ SUNDAY NIGHT FURTHER SOUTH AND WOULD JUST CLIP OUR FAR SOUTH. SINCE MODELS HAVE BEEN JUMPING AROUND SIGNIFICANT ON LOCATION OF THIS SYSTEM... WILL CONTINUE WITH PERSISTENCE FOR NOW UNTIL THERE IS A CLEAR TREND. PRECIPITATION TYPE ISSUES STILL CONTINUE WITH THIS SYSTEM WILL PRECIPITATION COULD END UP AS LIGHT SNOW...FREEZING RAIN OR SLEET. THE SYSTEM FOR TUESDAY CONTINUE TO BE PROBLEMATIC AS THE ECMWF CONTINUES TO GO BACK AND FORTH WITH SURFACE LOW TRACKING WEST OF GREEN BAY. THE GFS CONTINUED THIS TREND ON THE MORNING RUN...BUT 12Z ECMWF HAS NO SUCH FEATURE ON THIS RUN. WILL CONTINUE WITH PERSISTENCE WITH THIS PERIOD AS WELL UNTIL MODELS CONVERGE ON A CLEAR SOLUTION. AT OR ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY...THEN BELOW NORMAL TEMPERATURES ARE EXPECTED LATE NEXT WEEK AS ANOTHER SURGE OF ARCTIC AIR WILL SWEEP INTO THE NORTHERN UNITED STATES. && .AVIATION...FOR 06Z TAF ISSUANCE. A BRIEF PERIOD OF IFR CONDITIONS EXPECTED WITH SNOW BAND SWEEPING ACRS C AND E-C WI. SHOULD SEE A PERIOD OF VFR CONDITIONS FOR SEVERAL HRS AFTER THAT...BEFORE CONDITIONS WORSEN AGAIN. SKOWRONSKI && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 AM TO 3 PM CST FRIDAY FOR WIZ037>039-048-049. WINTER WEATHER ADVISORY UNTIL 3 PM CST FRIDAY FOR WIZ040-050. WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR WIZ011>013- 019>021-030-031. WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR WIZ005-010-018. WINTER WEATHER ADVISORY UNTIL 3 PM CST FRIDAY FOR WIZ022-073-074. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
352 AM CST SUN JAN 27 2013 .DISCUSSION... SHORT TERM (THROUGH MONDAY)... FORTHCOMING... LONG TERM (MONDAY NIGHT THROUGH FRIDAY)... 311 AM CDT MOTHER NATURE LOOKS TO HAVE SOMETHING FOR ALMOST EVERYONE DURING THIS PERIOD WITH THE POTENTIAL FOR THUNDERSTORMS (SEVERE?)...HEAVY RAIN/FLOODING...RECORD WARMTH...GUSTY WINDS...AND COLD WITH BIG ACCUMULATING SNOW ABOUT THE ONLY THING MISSING! SERIES OF WEAK IMPULSES WILL RIPPLE THROUGH THE BRISK SOUTHWESTERLY FLOW ALOFT AS DEEP TROUGH PROGRESSES EASTWARD INTO THE PLAINS. ONE SUCH WAVE AND ITS ASSOCIATED SURFACE LOW PROGGED TO AFFECT THE REGION MONDAY NIGHT WITH WARM FRONT PROGGED TO LIFT NORTH ACROSS THE AREA SENDING UNSEASONABLY WARM AND HUMID AIR FLOODING NORTHWARD INTO THE AREA. STRONG WAA/ASCENT ON THE NOSE OF THE 50KT+ LOW LEVEL JET SHOULD TRANSPORT MOISTURE/ELEVATED INSTABILITY NORTHWARD WHICH LOOKS TO BE ENOUGH TO SUPPORT ELEVATED CONVECTION MONDAY NIGHT AND HAVE INTRODUCED THUNDERSTORMS INTO THE GRIDS MONDAY NIGHT. TUESDAY LOOKS TO BE A BREEZY AND UNSEASONABLY WARM AND HUMID DAY WITH RECORD HIGHS IN JEOPARDY. WRF-NAM IS A BIT FASTER WITH THE TROUGH AND FARTHER EAST WITH THE FRONT BUT IS AN OUTLIER WITH THE GFS/UKMET/ECMWF/GEM ALL SLOWER AND SUPPORTING RECORD WARMTH OVER THE ENTIRE CWA. HAVE BUMPED UP HIGHS TUESDAY TO BE IN LINE WITH THE MAV GUIDANCE...AND CONSIDERING THE TYPICAL INABILITY OF MOS TO CAPTURE RECORD WARMTH EVEN THESE FORECAST NUMBERS COULD BE A HAIR CONSERVATIVE. ACCOMPANYING THE WARM TEMPERATURES LOOKS TO BE APRIL LEVEL HUMIDITY WITH DEWPOINTS PROGGED TO CLIMB INTO THE 55-60F RANGE WHICH IF IT PANS OUT WOULD ALLOW FOR AT LEAST WEAK SURFACE BASED INSTABILITY TO DEVELOP AHEAD OF A STRONG COLD FRONT THAT MOVES THROUGH LATE TUES INTO TUES NIGHT. WILL LIKELY SEE LEFT OFF SHOWERS/STORMS MOVE OUT EARLY TUES MORNING WITH MANY DRY HOURS EXPECTED BEFORE THE NEXT UPSTREAM WAVE LEADS TO MORE WIDESPREAD SHOWERS AND THUNDERSTORMS DEVELOPING/MOVING INTO THE AREA LATER TUESDAY. UPPER FLOW IS PROGGED TO BECOME FAIRLY WELL ALIGNED WITH THE SURFACE FRONT FAVORING SLOW EASTWARD PROGRESS OF THE BLOSSOMING AREA OF RAIN/THUNDERSTORMS WITHIN THE WARM CONVEYOR BELT. NOT SURPRISINGLY GIVEN DEWPOINTS NEARING 60F...PWATS ARE PROGGED TO CLIMB TO NEAR RECORD LEVELS FOR JANUARY WHICH REALLY RAISES CONCERNS ABOUT HEAVY RAINFALL AND FLOODING. UKMET/GEM/ECMWF ALL SUGGEST THAT OUR SE CWA WILL BE UNDER THE GUN FOR THIS HEAVY RAINFALL WHILE THE GFS IS MORE OF AN EAST OUTLIER FOCUSING THE HEAVY RAIN EAST OF OUR CWA. GOING TO SIDE CLOSER TO THE MODEL CONSENSUS AND BUMP UP POPS TO CATEGORICAL SE CWA AND INCLUDE MENTION OF HEAVY RAINFALL IN THE GRIDS/ZFP. FOR FURTHER DETAILS SEE HYDROLOGY SECTION BELOW. WHILE IT WOULD BE VERY RARE...CANNOT COMPLETELY RULE OUT A SEVERE THREAT IN THE AREA TUESDAY AS THE UNSEASONABLY HIGH DEWPOINTS COULD RESULT IN WEAK (BUT SUFFICIENT) INSTABILITY TO SUPPORT SEVERE THUNDERSTORMS IN AN ENVIRONMENT OF VERY STRONG SHEAR AND INCREASING LARGE SCALE ASCENT. THE NEW SWODY3 OUTLOOK JUST CAME OUT AND HAS INCLUDED A SLIGHT RISK INTO OUR CWA TUESDAY AND AS BEST I CAN RECALL THIS MAY BE THE FIRST EVER DAY 3 SLIGHT RISK IN OUR CWA IN JANUARY. AS UPPER TROUGH AND ASSOCIATED SURFACE FRONT CONTINUE EASTWARD LOOK FOR BAND OF RAIN/THUNDERSTORMS TO GRADUALLY MOVE EAST OF THE AREA TUESDAY NIGHT WITH NORTHWEST WINDS USHERING IN MUCH COLDER CONDITIONS. WEDNESDAY GENERALLY LOOKS TO BE DRY BUT WITH UPPER TROUGH MOVING THROUGH THE REGION HAVE OPTED TO HANG ONTO SLIGHT CHANCE OF LIGHT SNOW/FLURRIES...BUT MORE LIKELY THAN NOT MAJORITY OF THE DAY WILL BE DRY. HAVE MAINTAINED DRY FORECAST THURS/FRIDAY BUT CERTAINLY CAN`T RULE OUT A NORTHWEST FLOW "SURPRISE" BRINGING SOME LIGHT SNOW TO THE REGION AT SOME POINT IN TIME. BEST CHANCE MIGHT BE LATER THURSDAY INTO THURSDAY NIGHT AS RE-ENFORCING SHOT OF ARCTIC AIR IS PROGGED TO ARRIVE. COULD ALSO BE SOME LIGHT SNOW HEADING INTO NEXT WEEKEND AS MILDER AIR MOVES IN AND ARCTIC AIRMASS TEMPORARILY RETREATS. 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 && .HYDROLOGY... 311 AM CST USGS ANALYSIS OF STREAMFLOW ACROSS THE CWA INDICATES THAT STREAMFLOW IS CERTAINLY BELOW AVERAGE OVER THE CWA...THOUGH LESS SO OVER THE IROQUOIS...KANKAKEE...AND VERMILLION RIVER BASINS THAN SOME OF THE BASINS FARTHER NORTH. THOSE SAME RIVER BASINS APPEAR TO BE AT RISK FOR THE HEAVIEST RAINFALL EARLY THIS WEEK WITH WIDESPREAD TOTALS OF 1-2 INCHES LOOKING LIKE A GOOD BET AND TOTALS IN EXCESS OF 2 INCHES POSSIBLE. THIS HEAVY RAIN WOULD BE FALLING ON FROZEN GROUND AND LIKELY RESULT IN MUCH LOWER THAN AVERAGE INFILTRATION RATES AND GREATER RUNOFF INCREASING THE THREAT OF FLOODING. RIVER ICE SPOTTER REPORTS FROM 1/24 INDICATE THAT THERE IS A GREAT DEAL OF ICE COVERAGE ON THE IROQUOIS AND KANKAKEE RIVERS...AND THIS IS LIKELY THE CASE ON OTHER STREAMS/RIVERS AS WELL. THE COMBINATION OF RECORD WARMTH AND RAPIDLY INCREASING STREAMFLOW COULD RESULT IN A HEIGHTENED RISK OF ICE JAM FLASH FLOODING AS ICE BECOMES DISLODGED AND SIGNIFICANT ICE FLOW BEGINS. WHILE THE MOST SIGNIFICANT THREAT OF HEAVY RAINFALL AND FLOODING APPEARS TO BE OVER THE SOUTHEAST 1/3RD OR SO OF THE CWA...AT LEAST MODERATE RAINFALL AND RECORD WARMTH COULD RESULT IN AN INCREASED RISK OF ICE JAM FLOODING OVER NORTH CENTRAL ILLINOIS AS WELL. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * FREEZING RAIN DEVELOPS TOWARD MIDDAY...POSSIBLY STARTING AS A PERIOD OF SLEET * CIGS/VSBY FALLING TO MVFR SUNDAY AFTERNOON AND EVENTUALLY IFR SUNDAY EVENING * FREEZING RAIN CHANGES TO RAIN LATE THIS AFTERNOON OR EARLY THIS EVENING AS TEMPS RISE ABOVE FREEZING * IFR/LIFR CONDITIONS LIKELY FROM MID/LATE EVENING THROUGH OVERNIGHT TONIGHT IZZI //DISCUSSION...UPDATED 09Z... HAVE NUDGED THE TIMING OF THE ARRIVAL OF THE PRECIP UP JUST A BIT BASED ON RADAR TRENDS OF LARGE SHIELD OF PRECIPITATION OVER MO MARCHING RATHER STEADILY NORTHEASTWARD. TEMPERATURES HAVE BEEN RISING QUITE QUICKLY AHEAD OF THE PRECIPITATION WITH PRECIP ALMOST ENTIRELY RAIN AT THIS TIME. DRIER AIR IN ADVANCE OF THE RAIN OVER NORTHERN ILLINOIS COULD SLOW ITS PROGRESSION A BIT BY EATING AWAY SOME OF THE LEADING EDGE AND EVAPORATIVE COOLING COULD BE ENOUGH TO COOL TEMPS SLIGHTLY. GIVEN UPSTREAM TRENDS CONFIDENCE IN FREEZING TODAY HAS WANED SOME AND THE TREND OF TEMPS RISING QUICKLY AHEAD OF THE PRECIP CONTINUES THE THREAT OF FZRA/PL MAY BE LOWER OR THE TIME WINDOW OF OCCURANCE SHORTER. PARTICULARLY CONCERNING SEEING THE LATEST RAP MODEL SHOWING TEMPS NEARING 40F AHEAD OF THE PRECIP OVER THE CHICAGO AREA...IF THIS VERIFIES THERE MAY NOT BE MUCH FROZEN/FREEZING PRECIP. NOT PLANNING ANY BIG OVERHAULS TO THE TAF FORECAST NOW BASED ON THAT ONE MODELS BUT WILL CONTINUE TO CLOSELY MONITOR TRENDS. HAVE SHORTENED THE FORECAST DURATION OF THE FZRZ IN THE TAFS WITH THIS UPDATE CYCLE. IZZI UPDATED 06Z... AN UPPER LEVEL DISTURBANCE AND WARM FRONT LIFTING NORTH ACROSS THE REGION WILL RESULT IN A PERIOD MIXED PRECIPIATION SUNDAY AFTERNOON BEFORE CHANGING TO ALL RAIN SUNDAY EVENING. FORECAST SOUNDINGS SUGGEST THAT SATURATION WILL TAKE PLACE FROM TOP-DOWN WHICH SUGGESTS THAT PRECIP COULD BRIEFLY START AS A PERIOF OF SLEET BEFORE STRONG WARM AIR ADVECTION RESULTS IN A CHANGE OVER TO FREEZING RAIN. CONFIDENCE IS LOW ON HOW QUICKLY SFC TEMPS WILL RISE ABOVE FREEZING BUT DOES APPEAR AS THOUGH AT LEAST A COUPLE HOURS...POSSIBLY LONGER...OF FZRA IS LIKELY LATER SUNDAY AFTERNOON INTO EARLY SUNDAY EVENING. STEADY RAIN EXPECTED TO END SUNDAY EVENING BUT DRIZZLE AND PERIODIC LIGHT RAIN COULD LINGER THROUGH THE NIGHT SUNDAY. INITIALLY VFR CIGS SHOULD BUILD DOWN TO MVFR AND EVENTUALLY IFR SUNDAY AFTERNOON/EVENING...WITH CORRESPONDING REDUCTION IN VSBY EXPECTED...ESPECIALLY SUNDAY EVENING AS CIGS LOWER AND SOME LIGHT FOG/DRIZZLE DEVELOPS. IZZI //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN START TIME OF PRECIP * LOW-MEDIUM CONFIDENCE IN PRECIP TYPE TODAY * HIGH CONFIDENCE IN ANY FREEZING PRECIP CHANGING TO ALL RAIN...BUT LOW CONFIDENCE IN TIMING OF CHANGE OVER * HIGH CONFIDENCE IN THE GENERAL CIG/VSBY TRENDS...BUT LOW CONFIDENCE IN PRECISE TIMING * HIGH CONFIDENCE IN WINDS IZZI //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...IFR CIGS/VIS LIKELY WITH -RA/BR. TUESDAY...SHRA/TSRA LIKELY. MVFR LIKELY/IFR POSSIBLE. WEDNESDAY THROUGH FRIDAY...MVFR CIGS PROBABLE. A FEW PERIODIC FLURRIES OR LIGHT SNOW SHOWERS POSSIBLE. KREIN && .MARINE... 216 AM CST AN ACTIVE PERIOD LIES AHEAD ACROSS THE LAKE BUT AT THIS POINT PEAK WIND SPEEDS LOOK TO PRIMARILY REMAIN BELOW GALE FORCE THOUGH THERE MAY BE A FEW PERIODS THAT COME CLOSE. HIGH PRESSURE SPREAD FROM WESTERN QUEBEC INTO THE OHIO VALLEY. LOW PRESSURE IS DEVELOPING OVER THE SOUTHERN HIGH PLAINS AND WILL TRACK NORTHEASTWARD AND CROSS NORTHERN LAKE MICHIGAN MONDAY AFTERNOON. SOUTH WINDS WILL INCREASE TODAY AS THE INFLUENCE OF HIGH PRESSURE DEPARTS AND PRESSURE START TO FALL AHEAD OF THE LOW. EXPECT SPEEDS OF AROUND 30 KT LATER THIS AFTERNOON INTO THE EVENING ESPECIALLY OVER THE SOUTHERN PART OF THE LAKE BEFORE MUCH WARMER AIR TAKES OVER ALOFT SETTING UP AN INVERSION. THIS INVERSION LOOKS TO ALLOW WINDS TO EASE OVERNIGHT AND MONDAY MORNING KEEPING THE STRONGER 40 KT SPEEDS FROM REACHING THE LAKE SURFACE. WILL CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS FOR THE NEARSHORE BUT MAY BE ABLE TO MOVE THE END TIME EARLIER FOR THE INDIANA WATERS BUT WILL HOLD OFF FOR NOW AND LET LATER SHIFTS SEE HOW THINGS MATERIALIZE. THE SURFACE LOW WILL CROSS THE NORTHERN PART OF THE LAKE MONDAY AFTERNOON ALLOWING LIGHT WINDS FOR A TIME NORTH AS THE DIRECTION SHIFTS SOUTHWESTERLY ACROSS THE SOUTH. WEAK RIDGING THEN QUICKLY CROSSES THE LAKE MONDAY EVENING KEEPING LIGHT WINDS IN PLACE BUT ANOTHER SURFACE LOW WILL BE MOVING NORTHEASTWARD FROM THE SOUTHERN PLAINS RESULTING IN A QUICK SHIFT TO INCREASING SOUTHWESTERLY WINDS. AN INVERSION WILL REMAIN IN PLACE WITH MUCH WARMER AIR OVER THE LAKE SO THE 40+ KT SPEEDS AT AROUND 1000 FT ABOVE THE SURFACE WILL REMAIN THERE WHILE LAKE LEVEL WINDS ARE HELD TO LESS THAN 30 KT CENTRAL AND SOUTH...WITH LIGHTER WINDS FAR NORTH IN THE WEAK PRESSURE GRADIENT IN THE TROUGH OF THE APPROACHING LOW. THERE IS SOME INDICATION OF THE LOW SHIFTING FURTHER NORTH WHICH WOULD THEN LEAD TO MORE OF THE LAKE SEEING THESE STRONGER WINDS. A SECOND LOW FORMS SOUTHEAST OF THE LAKE LATER TUESDAY AS A COLD FRONT CROSSES THE LAKE SHIFTING WINDS TO THE NORTHWEST. MUCH COLDER AIR WILL SPILL IN BEHIND THE FRONT BRINGING UNSTABLE AIR BACK OVER THE LAKE. AT THIS POINT WIND SPEEDS DO NOT LOOK TO INCREASE MARKEDLY DESPITE THE COLD ADVECTION BUT THERE IS STILL SOME UNCERTAINTY IN HOW THE TWO LOWS EVOLVE SO THERE IS SOME POTENTIAL FOR INCREASED WINDS OVER WHAT IS CURRENTLY FORECAST TUESDAY NIGHT AND WEDNESDAY. SEVERAL WEAKER TROUGHS WILL CROSS THE REGION FROM WEDNESDAY THROUGH EARLY NEXT WEEKEND. WINDS WILL GENERALLY REMAIN WESTERLY WITH FLUCTUATIONS FROM SOUTHWEST TO NORTHWEST AS EACH TROUGH PASSES WITH PERIODIC INCREASES IN SPEEDS. WILL NEED TO MONITOR THE STRENGTH OF THESE AS IT WOULD NOT TAKE MUCH FOR THEM TO PRODUCE AT LEAST SHORT PERIODS OF GALES BUT FOR NOW WILL KEEP PEAK SPEEDS AROUND 30 KT. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FREEZING RAIN ADVISORY...ILZ008-ILZ010-ILZ011-ILZ019-ILZ021- ILZ032-ILZ039...9 AM SUNDAY TO 4 PM SUNDAY. FREEZING RAIN ADVISORY...ILZ012-ILZ013-ILZ014-ILZ020-ILZ022- ILZ023-ILZ033...11 AM SUNDAY TO 4 PM SUNDAY. FREEZING RAIN ADVISORY...ILZ005-ILZ006...11 AM SUNDAY TO 7 PM SUNDAY. FREEZING RAIN ADVISORY...ILZ003-ILZ004...9 AM SUNDAY TO 7 PM SUNDAY. IN...FREEZING RAIN ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...11 AM SUNDAY TO 4 PM SUNDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...NOON SUNDAY TO 4 AM MONDAY. SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...NOON SUNDAY TO 10 AM MONDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
429 AM EST SUN JAN 27 2013 .SHORT TERM...TODAY THROUGH MONDAY NIGHT FORECAST CONCERN FOR THE SHORT TERM WILL BE THE POTENTIAL OF A PERIOD OF FREEZING RAIN THIS AFTERNOON INTO THIS MAINLY THIS EVENING. ELEVATED ECHOES EVIDENT ON RADAR MOSAIC THIS MORNING FROM NORTH CENTRAL WISCONSIN INTO SOUTHERN LOWER MICHIGAN ASSOCIATED WITH LEADING EDGE OF STRONGER 850-700 HPA THETA ADV. THIS ELEVATED FORCING THIS MORNING WILL ONLY SERVE IN TOP DOWN SATURATION WITH DEEPER MOISTURE AND STRONGER LOW LEVEL THEATE ADVECTION SITUATED BACK ACROSS THE SOUTHERN/CENTRAL PLAINS WHERE RAIN HAS BEEN EXPANDING IN COVERAGE. 06Z RAP LOW LEVEL MOISTURE TRANSPORT PROGS DEPICTING STRONGEST 925 HPA TRANSPORT VECTORS INTO MISSOURI/SOUTHERN IOWA THIS AFTERNOON WITH ADVECTION SOMEWHAT DELAYED ACROSS LOCAL AREA DUE TO WEAK LOW LEVEL SOUTHEAST WIND COMPONENT ASSOCIATED WITH DEPARTING LOW LEVEL ANTICYCLONE. IT STILL APPEARS CHANCES OF PRECIP WILL INCREASE ACROSS WESTERN PORTIONS OF THE FORECAST AREA TOWARD THE 21Z TIMEFRAME BUT PRECIPITATION SHOULD BE INITIALLY VERY LIGHT. CANNOT COMPLETELY DISCOUNT A VERY BRIEF PERIOD OF A SNOW/SLEET MIX DUE TO WET BULB EFFECTS...BUT STRENGTH OF LOW LEVEL WARM/MOIST ADVECTION VIA AN APPROACHING 60 KNOT LOW LEVEL JET AXIS SHOULD SUPPORT PRECIP TYPE OF MAINLY SLEET/FREEZING RAIN MIX BY THE TIME MORE APPRECIABLE PRECIP RATES WOULD BE OBSERVED LATE THIS AFTERNOON AS LOW LEVELS SATURATE. STRENGTH OF LOW LEVEL MOISTURE ADVECTION AND INSPECTION OF RAP/NAM FORECAST SOUNDINGS EVEN OFFERS SOME QUESTION AS TO THE POSSIBILITY THAT ONCE LOW LEVEL SATURATION OCCURS...PRECIPITATION TYPE MAY BE MAINLY IN THE FORM OF RAIN ACROSS THE FAR SOUTH/SOUTHWEST. HAVE CONTINUED TO RELY MORE ON NAM IDEA IN TERMS OF INITIAL LOW LEVEL SATURATION/WET BULB PROCESSES WITH GFS OFTEN EXHIBITING A MOIST BIAS IN RAPID LOW LEVEL MOISTENING WITH THIS TYPE OF SETUP. IT STILL APPEARS AS THOUGH MOST LOCATIONS MAY RECEIVE A 2 TO 4 HOUR PERIOD OF MIXED PRECIP AND FREEZING RAIN THREAT BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING STILL APPEARS TO BE ACROSS THE FAR NORTHEAST WHICH IS ALSO SUPPORTED BY SREF PROBABILISTIC PRODUCTS. GIVEN INCREASING CONFIDENCE THAT PRIMARY IMPACTS WOULD BE FROM A PERIOD OF FREEZING RAIN WITH LITTLE IF ANY SLEET ACCUMULATION...WILL REPLACE THE WINTER WEATHER ADVISORY WITH A FREEZING RAIN ADVISORY. LATEST DATA CONTINUES TO SUGGEST THAT DURATION OF FREEZING PRECIP MAY BE SLIGHTLY SHORTER THAN PREVIOUSLY ANTICIPATED...ESPECIALLY ACROSS SOUTHERN HALF OF THE AREA BUT WILL KEEP TIMING OF WSW THE SAME FOR BOTH SEGMENTS AND OPT TO HOLD ONTO SOUTHERN PORTIONS OF THE ADVISORY AT THIS TIME. EVEN AFTER TEMPERATURES WARM ABOVE FREEZING THIS EVENING...RECENT VERY COLD TEMPS AND COLD GROUND CONDITIONS MAY STILL SUPPORT SOME FREEZING ON ROADWAYS FOR A TIME AFTER TEMPS RISE ABOVE FREEZING...ESPECIALLY ACROSS NORTHERN HALF. HAVE MAINTAINED ICE ACCUMULATIONS IN THE 0.05 TO 0.1 INCH RANGE...WITH THE HIGHER END OF THIS RANGE EXPECTED ACROSS FAR NORTH/NORTHEAST. BROAD ISENTROPIC UPGLIDE TO CONTINUE INTO MONDAY WITH ANOTHER LOW AMPLITUDE MID LEVEL WAVE TRACKING ACROSS THE GREAT LAKES REGION. NOT MUCH ORGANIZATION EXPECTED TO PRECIP ON MONDAY BUT WITH BROAD ISENTROPIC UPGLIDE AND WEAK MID LEVEL FORCING WILL CONTINUE TO CARRY HIGH RAIN POPS THROUGH MONDAY/MONDAY NIGHT. NEXT WARM FRONTAL SURGE ASSOCIATED WITH AMPLIFYING UPSTREAM LONGWAVE TROUGH SHOULD RESULT IN INCREASED PRECIP CHANCES MONDAY NIGHT WITH EVEN THE POSSIBILITY OF SOME EMBEDDED THUNDER ACROSS THE WEST LATE IN THE NIGHT. TEMPS SHOULD EXHIBIT NON DIURNAL TENDENCIES MONDAY NIGHT WITH THE WARM FRONT...POSSIBLY EVEN RISING INTO THE LOWER 50S ACROSS THE SOUTH BY MORNING. && .LONG TERM...TUESDAY THROUGH SATURDAY PROGRESSIVE HIGH AMPLITUDE TROUGH WILL BE FIRMLY IN PLACE ACROSS THE ROCKIES AT THE START OF THE PERIOD TUESDAY WITH A REMARKABLE 150+ KNOT MERIDIONAL UPPER LEVEL JET ON THE DOWNSTREAM SIDE. THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE IS IMPRESSIVE AND SEVERAL WAVES OF LOW PRESSURE ARE EXPECTED TO DEVELOP ALONG IT AS THE TROUGH INCHES ACROSS OUR REGION. BUT FIRST...OUR CWA WILL BE FIRMLY IN SOUTHWEST FLOW ON TUESDAY WITH CONTINUED WARM/MOIST AIR ADVECTION. 850MB DEWPOINTS CLIMB TO AROUND 10C WITH PW VALUES WELL OVER AN INCH BY LATE TUESDAY. SURFACE DEWPOINTS ALSO STILL EXPECTED TO CLIMB INTO THE MID 50S...MAKING FOR A VERY WARM DAY BY JANUARY STANDARDS. IN FACT...LATEST GUIDANCE IS SHOWING HIGHS NEAR OR ABOVE THE RECORDS (58 FOR SBN AND 62 FOR FWA...BOTH SET IN 1914). BUMPED UP HIGHS BUT WILL LEAVE THEM JUST BELOW 60F FOR MOST AREAS GIVEN CONCERNS OVER STILL VERY COLD GROUND TEMPERATURES. PRECIP CHANCES/AMOUNTS DURING THE DAY TUESDAY WILL DEPEND ON TIMING AND EVOLUTION OF LOW LEVEL JET WITH RAGGED ISENTROPIC ASCENT SUPPORTING MAINLY JUST SCATTERED SHOWERS UNTIL THE FRONT ARRIVES. MUCH BETTER FORCING WILL ARRIVE LATE TUESDAY WITH STRONG MIDLEVEL HEIGHT FALLS AND VERY FAVORABLE UPPER LEVEL JET DYNAMICS. THIS WILL FAVOR SURFACE CYCLOGENESIS SOMEWHERE OVER THE GREAT LAKES REGION WITH COPIOUS AMOUNTS OF RAINFALL ALONG THE TRAILING COLD FRONT. LATEST NAM BUFR SOUNDINGS ARE ALSO MUCH MORE OMINOUS REGARDING THUNDER POTENTIAL WITH ALMOST 1000 J/KG OF ELEVATED CAPE. THIS IS PROBABLY OVERDONE BUT GIVEN THE STRENGTH OF THE DEVELOPING LLJ COULD EASILY SEE SOME THUNDER OCCURRING LATE TUESDAY AND WILL ADD MENTION TO THE FORECAST. GIVEN THE POTENTIAL FOR CONVECTION COUPLED WITH STRONG WARM/MOIST AIR ADVECTION AHEAD OF THE FRONT AND EXCELLENT FORCING ALOFT...QPF AMOUNTS IN EXCESS OF AN INCH ARE POSSIBLE TUESDAY NIGHT. THIS CERTAINLY RAISES THE CONCERN FOR FLOODING WITH MELTING SNOWPACK IN THE NORTH AND LIKELY STILL FROZEN GROUND. ARCTIC AIR RETURNS BY LATE WEDNESDAY WITH THE REESTABLISHMENT OF NORTHWEST FLOW AND CAA. COLDEST AIR WILL TAKE SOME TIME TO FILTER INTO THE REGION SO THERE MAY BE A BRIEF LULL IN THE PRECIP BEFORE THE LAKE EFFECT GETS GOING BUT WILL MAINTAIN HIGH CHANCE POPS ON WEDNESDAY GIVEN UNCERTAINTY IN EXACT TIMING OF EXITING FRONT. WILL ALSO LIKELY BE AN ATYPICAL DIURNAL CURVE WITH AFTERNOON TEMPS FALLING FROM MORNING HIGHS AROUND 40F. LAKE RESPONSE DOESNT TRULY LIGHT UP UNTIL THURSDAY WITH THE APPROACH OF A VIGOROUS SHORTWAVE AND 850MB TEMPS BOTTOMING OUT IN THE LOW -20S. LAKE EFFECT SNOW WILL CONTINUE THROUGH FRIDAY BUT A WNW FETCH WILL LIKELY CONFINE BIGGEST IMPACTS TO OUR EXTREME NORTHERN COUNTIES. HIGH TEMPS DURING THIS PERIOD WILL LIKELY STRUGGLE TO GET ABOVE 20F GIVEN AFOREMENTIONED 850MB TEMPS. LOW LEVEL RIDGE AXIS SHIFTS EAST ON FRIDAY BUT ONLY A BRIEF RESPITE FROM PRECIP CHANCES BEFORE ANOTHER CLIPPER SYSTEM DIVES ACROSS THE REGION ON SATURDAY. && .AVIATION... 06Z TAFS...BACKING LOW LEVEL FLOW OVERNIGHT WILL ALLOW WARM/MOIST ADVECTION TO OCCUR THROUGH THE END OF THIS FORECAST PERIOD. STRONGEST ADVECTION IS EXPECTED DURING THE AFTERNOON/EVENING HOURS TODAY. THIS ADVECTION COMBINED WITH A FAST MOVING UPPER LEVEL DISTURBANCE KICKING OUT OF THE SOUTHERN ROCKIES WILL RESULT IN WIDESPREAD PRECIPITATION DEVELOPMENT OVERSPREADING NORTHERN INDIANA THIS AFTERNOON AND THIS EVENING. PRECIPITATION TYPES WILL CONTINUE TO BE TRICKY TO FORECAST...AT LEAST INITIALLY WHEN WET BULB EFFECTS MAY ALLOW FOR A BRIEF PERIOD OF SNOW OR SLEET BEFORE THERMAL/MOISTURE PROFILES ARE QUICKLY OVERWHELMED BY THE STRONG ADVECTION. THIS WILL LIKELY SUPPORT A PERIOD OF FREEZING RAIN IN THE EVENING. CURRENT INDICATIONS SUGGEST THE BEST CHANCE FOR FREEZING RAIN IN THE 00Z-04Z TIMEFRAME WITH SIMILAR CHANGEOVER TO RAIN TIMING CURRENTLY EXPECTED AT BOTH KFWA AND KSBN AFTER 04Z. A RAPID DETERIORATION IN CIGS TO MVFR EXPECTED THIS EVENING...AND THEN TO IFR LATER THIS EVENING AS COLUMN CONTINUES TO SATURATE. LIGHT AND VARIABLE WINDS AT 06Z...SHOULD BECOME SOUTHEAST AND INCREASE INTO THE 12G20KT RANGE FOR THE AFTERNOON BEFORE VEERING MORE SOUTHERLY TOWARD THE END OF THE PERIOD AS SFC LOW PRESSURE TRACKS INTO SOUTHEAST IOWA. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR INZ006-007-009. FREEZING RAIN ADVISORY FROM 3 PM EST /2 PM CST/ THIS AFTERNOON TO MIDNIGHT EST /11 PM CST/ TONIGHT FOR INZ003>005-008- 012>018-020-022>027-032>034. MI...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR MIZ078>081. FREEZING RAIN ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EST TONIGHT FOR MIZ077. OH...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR OHZ001-002-004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...MARSILI LONG TERM...AGD AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
400 AM CST SUN JAN 27 2013 .SYNOPSIS... 6Z SFC ANALYSIS HAS LOWS IN SOUTHEAST WYOMING AND EASTERN COLORADO WITH ASSOCIATED FRONTS CONNECTING THEM. A WEAK LOW WAS NEAR K9V9 IN SOUTH DAKOTA WITH A WARM FRONT RUNNING ROUGHLY ALONG THE MISSOURI RIVER INTO CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE GREAT LAKES WITH 20S AND HIGHER IN THE PLAINS AND LOWER MISSISSIPPI VALLEY. && .SHORT TERM...EARLY THIS MORNING AND TODAY... HEADLINES...HAVE TRANSITIONED TO A FREEZING RAIN ADVISORY FOR MOST OF THE AREA. AN ICE STORM WARNING HAS BEEN ISSUED FOR THE HWY 20 CORRIDOR FROM DBQ ON WEST. THERE SHOULD BE A QUICK ICE ACCUMULATION WITHIN THE FIRST COUPLE HOURS ONCE THE FREEZING RAIN BEGINS AT ANY ONE LOCATION. BASED ON CURRENT RADAR AND RAP TRENDS...FREEZING RAIN WILL BEGIN MOVING INTO THE FAR SOUTHWEST/WEST PARTS OF THE CWFA IN THE 10-12Z TIME FRAME. FCST SOUNDINGS SHOW CONSIDERABLE DRY AIR ACROSS THE AREA AND WBZ TEMPERATURES AT THE SFC AND 0.5 KM ARE BELOW FREEZING INITIALLY. THUS TREMENDOUS EVAPORATIVE COOLING WILL OCCUR TO HELP HOLD TEMPERATURES DOWN AND ALLOW SLEET TO MIX IN WITH THE FREEZING RAIN. BASED ON RAP TRENDS...TOP DOWN SATURATION WILL RAPIDLY OCCUR OVER ALL BUT THE FAR EASTERN PARTS OF THE CWFA BY MID MORNING. WBZ TEMPERATURES CONTINUE TO REMAIN BELOW FREEZING AT THE SFC AND AT 0.5 KM BUT WBZ TEMPERATURES SLOWLY RISE FROM SOUTHWEST TO NORTHEAST DURING THE MORNING. THUS FREEZING RAIN WITH SOME SLEET WILL BE SEEN ACROSS THE ENTIRE AREA DURING THE MORNING. TREMENDOUS WAA CONTINUES INTO THE AFTERNOON HOURS WHICH WILL ALLOW THE FREEZING RAIN/SLEET TO CHANGE OVER TO ALL RAIN FROM SOUTHWEST TO NORTHEAST. HOWEVER...MOST AREAS ALONG/NORTH OF HWY 30 WILL LIKELY SEE FREEZING RAIN/SLEET CONTINUE THROUGH THE AFTERNOON HOURS. DUE TO THE TREMENDOUS EVAPORATIVE COOLING THAT WILL OCCUR DURING THE DAY...TEMPERATURES MAY INITIALLY DROP SEVERAL DEGREES ONCE THE PRECIPITATION BEGINS. HOWEVER...THE SURGE OF MOISTURE MOVING NORTH INTO THE AREA WILL BODILY FORCE TEMPERATURES UP AGAIN AS THE DAY PROGRESSES. ..08.. .LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY... SUNDAY NIGHT THROUGH TUESDAY WILL BE A VERY ACTIVE PERIOD WITH CHALLENGING WEATHER THROUGHOUT. SUNDAY EVENING THE DAYTIME STORM SYSTEM GRADUALLY SHIFTS NORTHEAST. THE UPPER LEVEL SHORTWAVE SWEEPS NORTHEAST OF THE AREA...BUT THE STRONG WARM AIR ADVECTION AND MOISTURE ADVECTION CONTINUES AS A WEAK SURFACE LOW RIPPLES UP FROM KANSAS TO WISCONSIN OVERNIGHT. THE STRONG WARM AIR ADVECTION WILL CAUSE SURFACE TEMPERATURES TO CONTINUE TO WARM OVERNIGHT. WHILE TEMPERATURES ACROSS THE HIGHWAY 20 CORRIDOR WILL BE JUST BELOW FREEZING AS OF 00Z...THEY SHOULD RISE ABOVE FREEZING AROUND MID EVENING. THIS SHOULD END THE FREEZING RAIN THREAT FOR THE ENTIRE AREA BY 03Z TONIGHT. THUS...THE ENDING TIME OF THE NORTHERN MOST PORTIONS OF THE FREEZING RAIN ADVISORY AND ICE STORM WARNING. AFTERWARDS...A WEAK TROUGH MOVES ACROSS THE AREA OVERNIGHT. TEMPERATURES SHOULD REMAIN RELATIVELY WARM OVERNIGHT...ABOVE FREEZING. SO...WHILE I EXPECT SOME LINGERING LIGHT PRECIPITATION OVERNIGHT IN THE VICINITY OF THIS TROUGH AXIS...FREEZING RAIN SHOULD NOT BE A CONCERN. MONDAY AND TUESDAY THIS WEAK SURFACE TROUGH AXIS SAGS TO ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. AT UPPER LEVELS A LARGE SCALE TROUGH MOVES ACROSS THE ROCKIES MONDAY...AND OVER THE MIDWEST ON TUESDAY. THIS UPPER LEVEL TROUGH AND THE SOUTHWEST FLOW OVER THE MIDWEST AHEAD OF IT...IS EXPECTED TO GENERATE A NEW SURFACE LOW OVER EASTERN COLORADO...AND SWEEP NORTHEAST ACROSS IOWA OR WESTERN ILLINOIS ON TUESDAY. THE GFS IS THE FARTHEST WEST OF THE MODELS...AND RUNS THE SURFACE LOW OVER CENTRAL IOWA...WHILE THE NAM AND ECMWF ARE FARTHER EAST AND ARE CLOSER TO THE MISSISSIPPI RIVER. THIS IS GOING TO BRING ANOTHER SURGE OF WARM AIR INTO THE AREA MONDAY NIGHT AND TUESDAY...WITH HIGHS EXPECTED IN THE 40S AND 50S ON MONDAY AND TUESDAY...WITH VERY LARGE GRADIENTS ACROSS THE CWFA. WITH THE SURFACE LOW PASSAGE THERE SHOULD BE A SURGE OF RAINFALL...LIKELY WITH CONVECTIVE ELEMENTS EMBEDDED WITHIN IT. HAVE INCLUDED SOME ISOLATED THUNDER FOR PORTIONS OF THE AREA AS MID LEVEL LAPSE RATES AND THE DYNAMICS MAY BE ABLE TO SUPPORT SOME RUMBLES OF THUNDER. BEHIND THIS SURFACE LOW WE FINALLY GET THE COLD FRONT TO SWEEP THROUGH THE AREA...BRINGING MUCH COLDER AIR TO THE AREA TUESDAY NIGHT. WHILE I DO NOT EXPECT MUCH PRECIPITATION BEHIND THE COLD FRONT...WHAT IS THERE SHOULD GRADUALLY CHANGE OVER TO ALL SNOW OVERNIGHT. BY WEDNESDAY MORNING WE WILL BE BACK INTO THE COLD AIR AGAIN...WITH HIGHS ON WEDNESDAY IN THE 20S TO LOW 30S. STRONG COLD AIR ADVECTION THROUGH THE DAY WITH NORTHWEST FLOW BEHIND THE UPPER LEVEL TROUGH TO BRING A FRESH SURGE OF COLD AIR. THE 500MB COLD POOL IS PRETTY STEEP...SO WE MAY HAVE SOME INSTABILITY SHOWERS DURING THE DAY...BUT JUST ENOUGH UNCERTAINTY SO HAVE LEFT OUT FOR NOW. THURSDAY THROUGH SATURDAY THE MODELS KEEP US IN STRONG NORTHWEST FLOW WITH SOME HINTS AT A FAST MOVING SHORTWAVE TO DROP THROUGH AT SOME POINT. MODELS ARE QUITE DIFFERENT AT THIS TIME...AS CAN BE EXPECTED WITH SUCH A SMALL SCALE FEATURE. FOR NOW AM CARRYING SOME SLIGHT CHANCES FOR FRIDAY NIGHT AND SATURDAY...THOUGH WE MAY ALSO NEED SOME ON THURSDAY NIGHT AS WELL. TEMPERATURES WILL BE BACK TO COLDER THAN NORMAL VALUES FOR THIS TIME OF YEAR...WITH A WARM-UP EXPECTED ON SATURDAY TO NEAR NORMAL. LE && .AVIATION.../ISSUED 1137 PM CST SAT JAN 26 2013/ VFR CONDITIONS WILL BE OVER THE AREA THROUGH 12Z SUNDAY. CONDITIONS WILL RAPIDLY DETERIORATE DURING THE MORNING AS AN AREA OF FREEZING RAIN SPREADS NORTHEAST ACROSS THE AREA. IFR CONDITIONS ARE EXPECTED OVER THE ENTIRE AREA BY MID AFTERNOON. THE FREEZING RAIN SHOULD CHANGE TO RAIN ALONG AND SOUTH OF HIGHWAY 34 IN SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS DURING THE MORNING BUT IS EXPECTED TO CONTINUE NORTH OF THIS AREA THROUGH MUCH IF NOT ALL OF THE AFTERNOON. IFR TO LOW IFR CONDITIONS WILL REMAIN OVER THE AREA THROUGH THE EVENING. THERE MAY BE SOME POCKETS OF FREEZING RAIN OR FREEZING DRIZZLE IN THE FAR NORTH INCLUDING KDBQ HOWEVER...TEMPERATURES SHOULD BE ABOVE FREEZING IN MOST AREAS ENDING ANY WIDESPREAD FREEZING PRECIPITATION THREAT. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR JACKSON. FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR DES MOINES-HENRY IA-JEFFERSON-KEOKUK-LEE-VAN BUREN-WASHINGTON. FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR BENTON- CEDAR-CLINTON-IOWA-JOHNSON-JONES-LINN-LOUISA-MUSCATINE- SCOTT. ICE STORM WARNING UNTIL 9 PM CST THIS EVENING FOR BUCHANAN- DELAWARE-DUBUQUE. IL...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR CARROLL- JO DAVIESS-STEPHENSON. FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR HANCOCK- HENDERSON-MCDONOUGH-WARREN. FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR BUREAU- HENRY IL-MERCER-PUTNAM-ROCK ISLAND-WHITESIDE. MO...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR CLARK- SCOTLAND. && $$ LE/08
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1011 PM MST SAT JAN 26 2013 .UPDATE... ISSUED AT 755 PM MST SAT JAN 26 2013 UPDATE SENT FOR TONIGHT-SUNDAY PERIOD. AT 03Z WARM FRONT AND LIGHT RAIN PUSHING INTO THE SOUTHWEST AND WESTERN PART OF THE FORECAST AREA. AS THE WARM FRONT LIFTS NORTH/NORTHEAST OVERNIGHT EXPECT SOME RAIN ALONG AND NORTH OF IT WHILE TO THE SOUTH DECREASING CLOUDINESS EXPECTED. EXCEPTION WILL BE ACROSS THE EASTERN 1/3-1/4 OF THE AREA WHERE SOUTHERLY COMPONENT TO THE WIND WILL MAINTAIN HIGH BOUNDARY LAYER MOISTURE AND A THREAT FOR FOG. AS THE SYSTEM CONTINUES TO LIFT EAST/NORTHEAST ON SUNDAY NORTHWEST WINDS WILL DEVELOP ON THE BACKSIDE PUSHING THE LOW CLOUDS AND FOG OUT OF THE AREA BY MID TO LATE MORNING. ELSEWHERE MAY SEE SOME WRAPAROUND CLOUDINESS EARLY WITH NO PRECIPITATION EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 135 PM MST SAT JAN 26 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW SHORTWAVE RIDGING ACROSS THE SOUTHERN PLAINS WITH A SERIES OF SHORTWAVE TROUGHS OVER SOUTHERN CALIFORNIA AND OFF THE PACIFIC NW COAST. THE FIRST OF THESE TROUGHS OVER SOUTHERN CALIFORNIA WILL BE THE MAIN WEATHER PRODUCER FOR US TONIGHT WITH MID-HIGH CLOUDS ALREADY INCREASING AHEAD OF THIS FEATURE OVER COLORADO AND WESTERN KS. GUIDANCE IN GENERAL AGREEMENT ON PRECIP SPREADING FROM THE WEST TO THE EAST THROUGH THE EVENING HOURS...WITH BEST COVERAGE/CHANCES ACROSS THE EAST/NORTHEAST AFTER MIDNIGHT AS A WARM FRONT MOVES NORTH AND MOISTURE ADVECTION INCREASES. IM NOT AS CONFIDENT ABOUT COVERAGE DURING THE EVENING WITH MOISTURE ADVECTION BELOW H7 MARGINAL UNTIL 06Z. NAM IS ADVERTISING DRY SLOT QUICKLY MOVING FROM THE W/SW LATE THIS EVENING THROUGH SUNDAY MORNING...AND WITH STRONG DRY SLOT ALREADY APPARENT ON WV IMAGERY THIS MAY BE REASONABLE. I HAVE TRENDED POPS HIGHER ACROSS THE NORTHEAST AROUND 06-12Z...AND HAVE DECREASED POPS QUICKER ACROSS THE SW DURING THIS SAME TIME PERIOD. OVERALL QPF AMOUNTS SHOULD BE LIGHT...WITH HIGHEST TOTALS IN SW NEBRASKA AND NORTH CENTRAL KS WHERE UP TO 0.10 INCHES OF LIQUID IS POSSIBLE. AS WITH PREVIOUS FORECASTS I KEPT PRECIP TYPE ALL RAIN WITH MODEL SOUNDINGS SUPPORTING ALL LIQUID...AND SURFACE TEMPERATURES EXPECTED TO REMAIN ABOVE FREEZING WHERE PRECIP/CLOUD COVER IS LINGERING AFTER MIDNIGHT. BELOW FREEZING TEMPS WILL BE POSSIBLE IN THE W/SW WHERE SKIES WILL BE CLEARING...HOWEVER PRECIP WILL BE OVER WITH AT THAT POINT. WITH INCREASING LOW LEVEL MOISTURE ACROSS THE NORTH AND EAST WE COULD ALSO SEE PATCHY FOG DEVELOPMENT LATE TONIGHT INTO SUNDAY MORNING BEFORE THE WARM FROM FINAL PUSHES NORTH INTO CENTRAL NEBRASKA BEFORE 18Z...WITH DRY/STABLE CONDITIONS EXPECTED THROUGH THE REST OF SUNDAY. WITH CLEARING SKIES...AND 10-14C H85 TEMPS ADVECTING OVER THE CWA FROM THE WEST WE SHOULD SEE ANOTHER MILD DAY WITH TEMPERATURES IN THE MIDDLE 60S IN THE SOUTH TO THE LOW 50S NEAR MCCOOK WHERE CLOUD COVER MAY LINGER LONGER INTO THE AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 135 PM MST SAT JAN 26 2013 MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH MONDAY. SYSTEM WILL MOVE THROUGH MONDAY NIGHT BRINGING A CHANCE OF LIGHT SNOW AND COLDER TEMPERATURES. THERE COULD BE A BRIEF PERIOD OF LIGHT RAIN AHEAD OF THE FRONT...BUT IT WILL QUICKLY CHANGE TO SNOW. LIGHT SNOW OR FLURRIES COULD LINGER INTO TUESDAY...MAINLY IN THE MORNING. TOTAL SNOW ACCUMULATIONS FOR MONDAY NIGHT THROUGH TUESDAY CURRENTLY FORECAST TO BE AN INCH OR LESS. WIND DOES NOT APPEAR THAT IT WILL BE A PROBLEM. THE REMAINDER OF THE PERIOD WILL BE DOMINATED BY NORTHWEST FLOW ALOFT. GFS SHOWS SOME VERY LIGHT SNOW OR FLURRIES WEDNESDAY NIGHT WITH SUBTLE SHORTWAVE IN THE FLOW...OTHERWISE DRY. TEMPERATURES WILL SLOWLY REBOUND FROM THE TUESDAY COOL DOWN...NEAR NORMAL WEDNESDAY AND THURSDAY THEN SLIGHTLY ABOVE NORMAL FRIDAY AND SATURDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1000 PM MST SAT JAN 26 2013 FOR KGLD VFR THROUGH THE PERIOD. WARM FRONT AND BAND OF LIGHT RAIN HAS PUSHED JUST TO THE NORTH OF THE TERMINAL AND SHOULD SEE A DECREASE IN CLOUDINESS TIL SUNDAY MORNING WHEN SOME WRAPAROUND CLOUDINESS MAY EXTEND AS FAR SOUTH AS THE TERMINAL BEFORE EXITING THE AREA TO THE EAST/NORTHEAST. SOUTH WINDS 10KTS WILL VEER TO THE WEST AT 10KTS BY 10Z THEN NORTHWEST BY 17Z WITH GUSTS AROUND 18KTS POSSIBLE BEFORE BECOMING VRB05KTS BY SUNSET. SOUTH WINDS AROUND 10KTS WILL DEVELOP TOWARD THE END OF THE PERIOD. FOR KMCK SHOULD HAVE LIGHT RAIN THROUGH 07-08Z THEN SOME FOG WITH MVFR/IFR CIGS/VIS THROUGH 15-17Z AS WINDS ARE LIGHT AND BOUNDARY LAYER MOISTURE IS HIGH. DURING THE AFTERNOON HOURS SUNDAY MVFR/IFR CIGS/VIS WILL MOVE AWAY FROM THE TERMINAL AS WINDS BECOME NORTHWEST AROUND 10KTS. BY 23Z VRB04KT WINDS EXPECTED AND SHOULD CONTINUE THROUGH THE REST OF THE TAF PERIOD UNDER GENERALLY A CLEAR SKY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...DR LONG TERM...024 AVIATION...99
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1244 AM EST SUN JAN 27 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 421 PM EST SAT JAN 26 2013 LAKE EFFECT HAS BEEN GRADUALLY DIMINISHING THROUGH THE AFTERNOON HOURS...AS THE NORTHERLY FLOW HAS SLOWED WITH HIGH PRESSURE MOVING OVER THE CWA. STILL HAVE SOME LIGHT SNOW SHOWERS OVER THE NORTH CENTRAL CWA...BUT EXPECT THEM TO END OR PUSH NORTH DURING THE LATE AFTERNOON AND EARLY EVENING. OTHERWISE...A FAIRLY NICE AFTERNOON WITH LIGHT WINDS AND TEMPERATURES AT OR SLIGHTLY BELOW NORMAL AS OF 3PM. HIGH PRESSURE CENTERED OVER THE UPPER GREAT LAKES WILL SHIFT EAST TONIGHT AS THE UPPER RIDGE BUILDS NORTHEAST INTO THE UPPER MISSISSIPPI VALLEY. AS THIS OCCURS...BROAD H800-600 WARM AIR ADVECTION CURRENTLY IN MINNESOTA AND STARTING TO MOVE INTO WESTERN LAKE SUPERIOR WILL CONTINUE EAST ACROSS THE CWA TONIGHT. SO FAR TODAY...HAVE ONLY SEEN A FEW OBS REPORTING SNOW SHOWERS FROM THIS MID CLOUD DECK IN NORTHERN MN...WHICH WAS LIKELY HELD OFF BY DRY H925-850 AIR SEEN ON 12Z KINL SOUNDING AND RUC SOUNDINGS IN THAT AREA. LATEST MODELS DO TRY TO MOISTEN THE CENTRAL CWA TOWARDS MIDNIGHT...AS THE STRONGER H925-850 WAA SLIDES EAST ALONG THE WI BORDER. NOT LIKING HOW QUICKLY THINGS MOISTEN...BUT WITH THE IDEA IN SEVERAL MODELS...WILL ADD SLIGHT CHANCES THERE. WILL KEEP THE BEST POPS OVER THE NORTHERN HALF OF LAKE SUPERIOR WHERE THE LOWER LEVELS WERE A LITTLE MORE MOIST AND THE MID LEVEL WAA WAS THE STRONGEST. ALSO ADDED A MENTION OF FLURRIES TO AREAS SURROUNDING THE POPS TO ACCOUNT FOR SOME SNOW MAKING IT THROUGH THE DRY AIR. THE OTHER ITEM OF CONCERN HEADING INTO THE OVERNIGHT HOURS WILL BE THE INCREASED MOISTENING OF THE LOWER LEVELS OFF LAKE MICHIGAN. AS THIS OCCURS...THE H850 TEMPS WILL BE WARMING TOWARDS -10C OVERNIGHT...SO DON/T EXPECT LAKE ENHANCEMENT TO GET TOO OUT OF HAND. BUT WITH THE SNOW ALOFT FEEDING INTO THE LOWER LEVELS FORCING THAT IS MAINLY BELOW -10C...EXPECT SNOW TO DEVELOP THERE. H925 WINDS ARE FAVORABLE FOR SOUTHERN LUCE AND SOUTHEAST SCHOOLCRAFT...SO HAVE INCREASED POPS INTO LOW END LIKELY VALUES FOR THOSE LOCATIONS AND TAPERED IT OFF FAIRLY QUICKLY TO THE WEST. WITH SNOW RATIOS ON THE LOW END...AROUND 10-14 TO 1 INITIALLY AND TRENDING TOWARDS 8-1 SUNDAY MORNING...EXPECT ACCUMULATIONS TO BE FAIRLY LIGHT IN THOSE AREAS WITH ONLY AN INCH OF ACCUMULATION. THE LAKE EFFECT SHOULD DIMINISH LATER SUNDAY MORNING INTO THE EARLY AFTERNOON DUE TO THE CONTINUED WARMING OF TEMPS ALOFT SHOVING INVERSION HEIGHTS TO 3KFT. SUNDAY LOOKS TO BE FAIRLY QUIET...AS THE AREA IS BETWEEN THE EXITING WARM AIR ADVECTION PRECIPITATION AND THE NEXT APPROACHING SYSTEM FOR SUNDAY NIGHT. THE NEXT WAVE IS CURRENTLY OVER SOUTHERN CALIFORNIA AND QUICKLY MOVES NORTHEAST AND TOWARDS THE AREA TONIGHT AND SUNDAY. WITH THE INCREASED CONSISTENCY IN THE MODELS...HAVE DELAYED THE START OF THE PRECIPITATION UNTIL 00Z AND LATER. THE LONG TERM DISCUSSION WILL COVER THIS SYSTEM IN FURTHER DETAILS. OTHERWISE...WILL SEE A GAP IN THE CLOUDS BEHIND THE WAA CLOUDS DEPARTING IN THE MORNING AND THE INCREASING CLOUDS FROM THE SOUTHWEST IN THE AFTERNOON. THINK THIS CLEARING WILL BE MOST LIKELY OVER THE WEST HALF AND HAVE TRENDED TOWARDS PARTLY-MOSTLY SUNNY SKY FOR PERIOD AROUND MID DAY. FARTHER EAST...NAM/GFS ARE HINTING AT SOME LOWER CLOUDS DEVELOPING TONIGHT AND REMAINING THROUGH MUCH OF SUNDAY. NOT OVERLY CONFIDENT ON THIS SOLUTION WITH THE DRY AIR UPSTREAM...BUT WITH THE EXITING MID CLOUDS AND APPROACHING HIGH CLOUDS...A PARTLY-MOSTLY CLOUDY FORECAST SEEMED WARRANTED. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 421 PM EST SAT JAN 26 2013 EARLY PORTION OF THE LONG TERM PERIOD SHOULD BE FAIRLY ACTIVE AS PATTERN UNDERGOES SIGNIFICANT TRANSITIONS NEXT WEEK. CURRENT ERN NAMERICA TROF IS IN THE PROCESS OF WEAKENING...AND IT WILL LIFT OUT OVER THE NEXT COUPLE OF DAYS AS A TROF AMPLIFYING OVER THE WRN CONUS FORCES DOWNSTREAM RIDGING OVER THE ERN CONUS INTO SE CANADA. THIS WILL LEAD TO A SUBSTANTIAL WARMUP FOR THE UPPER LAKES. AS THE WRN TROF THEN SHIFTS E...IT APPEARS PATTERN WILL RETURN TO SOME FORM OF THE RECENT PATTERN WITH WRN RIDGING/ERN TROFFING. THIS WILL SUPPORT A TREND BACK TO BLO NORMAL TEMPS FOR THE LAST HALF OF THE WEEK AND A RETURN OF PERSISTENT LES OFF LAKE SUPERIOR. WHILE IT DOESN`T HAPPEN TOO OFTEN...CONFIDENCE IN THE LATTER PORTION OF THE LONG TERM IS MUCH MUCH HIGHER THAN THE EARLY PART. DURING THE EARLY PART...THERE REMAINS CONSIDERABLE UNCERTAINTY IN THE EVOLUTION OF THE WRN TROF THRU THE CNTRL INTO ERN CONUS. THAT UNCERTAINTY CENTERS AROUND WHETHER THE PIECE OF ENERGY IN THE SRN PART OF THE WRN TROF LIFTS OUT AND PHASES WITH ENERGY DROPPING SE OUT OF CANADA. MORE ON THAT LATER. BEGINNING SUN NIGHT...ATTENTION WILL BE ON THE SHORTWAVE THAT IS CURRENTLY LIFTING NE ACROSS AZ IN RESPONSE TO TROF THAT IS NOW AMPLIFYING ALONG THE W COAST. WAVE LOOKS VERY WELL-DEFINED ON WATER VAPOR IMAGERY WITH AN ASSOCIATED PLUME OF PACIFIC MOISTURE. AS SHORTWAVE CONTINUES TO LIFT NE...MODELS SHOW A NICE SHALLOW STREAM OF MOISTURE GETTING TAPPED OFF THE GULF. SO...WITH THE SHALLOW MOISTURE FEED...WAA/ISENTROPIC ASCENT AHEAD OF WAVE WILL LEAD TO AN AREA OF PCPN DEVELOPING ACROSS THE CNTRL PLAINS AND THEN EXPANDING AS IT SHIFTS INTO THE GREAT LAKES. PRECIPITABLE WATER ALSO INCREASES TO 200-300PCT OF NORMAL. SO IF FORCING IS STRONG...MAY SEE SOME DECENT PCPN AMOUNTS. OVERALL...MODELS ARE TRENDING SLIGHTLY MORE DEFINED WITH SHORTWAVE WHICH LOOKS ON TRACK GIVEN CURRENT WATER VAPOR IMAGERY AND DESPITE THE FACT THAT IT WILL BE WEAKENING AS IT LIFTS NE THRU THE BUILDING LARGER SCALE RIDGE. MODELS ARE ALSO TRENDING A LITTLE FARTHER N AND W WITH ASSOCIATED PCPN. NAM/REGIONAL GEM REPRESENT THE THE NW SIDE OF THE 12Z MODEL RUNS WITH BOTH SPREADING PCPN SQUARELY ACROSS UPPER MI. NAM HAS AMOUNTS FROM 0.25-0.6 INCHES WHILE THE GEM HAS 0.15-0.3 INCHES. ALTHOUGH A LITTLE SKEPTICAL OF THESE MORE NW SOLUTIONS...TRENDS FROM REMAINING GUIDANCE STILL SUPPORT CONTINUING TREND FROM PREVIOUS FCST TO BUMP UP POPS FOR SUN NIGHT. PER 295K SFC...A HEALTHY PUSH OF ISENTROPIC ASCENT IS INDICATED TO SPREAD INTO THE GREAT LAKES REGION WHICH SHOULD LEAD TO A DECENT AREA OF PCPN. PTYPE MAY BE AN ISSUE AS 850MB TEMPS RISE TO AROUND 0C SUN. HOWEVER...WITH WETBULB PROFILE BLO 0C...SEEMS LIKELY THAT TEMP PROFILE WILL QUICKLY FALL SUBZERO DUE TO EVAPORATIVE COOLING AS WELL AS DYNAMIC COOLING. PLAN FOR NOW WILL BE TO UTILIZE JUST SNOW AS PTYPE SUN NIGHT. 295K SFC SHOWS MIXING RATIOS AROUND 4G/KG...SUGGESTING POTENTIAL FOR UP TO 8 INCHES OF SNOW WHERE MAX ASCENT OCCURS. SINCE DURATION OF PCPN WILL PROBABLY BE ON THE ORDER 9HRS...HIGH END SNOW TOTALS COULD REACH 6 INCHES IF MAX FORCING DOES SPREAD INTO UPPER MI. WILL CONTINUE TO PAINT THE HIGHER PCPN AMOUNTS OVER THE SE FCST AREA WHERE SNOW AMOUNTS OF 2 TO 4 INCHES WILL BE INCLUDED FOR THIS FCST. MAY SEE 1-2 INCHES NW. ON THE BACKSIDE OF SNOW AREA...PCPN MAY TRANSITION TO SOME -FZDZ SW TO NE MON MORNING AS MID LEVEL MOISTURE PULLS OUT. THERE SHOULD THEN BE A TREND TO DRY WEATHER DURING THE DAY MON. OVER THE LAST FEW DAYS...THE BIGGEST UNCERTAINTY HAS BEEN THE TUE/WED TIME PERIOD DUE TO THE CONSIDERABLE SPREAD OF SOLUTIONS REGARDING THE EASTWARD PROGRESSION/EVOLUTION OF THE CURRENTLY AMPLIFYING WRN CONUS TROF. MAIN POINTS OF UNCERTAINTY INVOLVE WHETHER THE ENERGY IN THE BASE OF THE WRN TROF DROPS OUT AND HANGS BACK OVER THE SW...OR IF IT DOES NOT...WILL IT LIFT NE AND PHASE WITH ENERGY DROPPING SE TOWARD THE GREAT LAKES. THE ECMWF HAD SEVERAL RUNS FAVORING THE IDEA OF DROPPING THE ENERGY OUT. IT IS NOW TRENDING BACK TO KEEPING THE SRN PORTION PROGRESSIVE...BUT IT DOES NOT LIFT ENERGY NE TO PHASE WITH THE NRN PORTION IN THE GREAT LAKES REGION. THE GFS HAS HAD THE MOST RUNS FAVORING PHASING OF ENERGY IN THE VCNTY OF THE GREAT LAKES WITH THE GLOBAL GEM/UKMET ALSO GENERALLY LEANING IN THAT DIRECTION ON MOST RUNS. AGAIN...AS IN PREVIOUS DAYS...THERE ARE A FEW GFS ENSEMBLES THAT HAVE A DEEP STORM MOVING NE THRU THE UPPER LAKES REGION. AT THIS POINT...GIVEN THE SPREAD OF SOLUTIONS...PARTICULARLY WITH REGARD TO THE ALWAYS UNCERTAIN PHASING OF STREAMS AND LOCATIONS OF SUCH OCCURRENCE... THERE IS NOT ENOUGH CONFIDENCE TO REALLY TREND INHERITED FCST MUCH IN ANY DIRECTION. SO...AS HAS BEEN THE CASE IN RECENT DAYS...BEST PATH WILL CONTINUE TO BE TO USE A CONSENSUS OF RECENT MODEL RUNS UNTIL THE DETAILS ARE SORTED OUT. GIVEN THE WARMTH PUSHING INTO THE AREA OVER THE NEXT FEW DAYS...MIXED PCPN COULD BE AN ISSUE...AND FOR THIS FCST ISSUANCE WILL KEEP A MENTION OF A MIX...RANGING FROM MOSTLY RAIN FOR A TIME SE TO MAINLY SNOW NW. DEPENDING ON TRACK OF SFC LOW AND WHETHER IT DEEPENS SUBSTANTIALLY...THERE COULD BE A TRANSITION TO SIGNIFICANT SNOW/BLSN LATER TUE INTO WED NEAR LAKE SUPERIOR WHERE LAKE ENHANCEMENT/LES WILL GET UNDERWAY. LAKE SUPERIOR LES WILL THEN BE THE RULE WED THRU FRI AS ARCTIC AIR SETTLES OVER THE AREA (850MB TEMPS FALL TO -20 TO -25C). UTILIZED CATEGORICAL POPS FOR THE USUAL AREAS FAVORED BY NW WINDS WED THRU FRI GIVEN VERY HIGH CONFIDENCE IN LES. CLIPPER TYPE SYSTEM ARRIVING SAT MAY RESULT IN -SN SPREADING INTO AREAS AWAY FROM LES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1242 AM EST SUN JAN 27 2013 VFR CONDITIONS WILL CONTINUE AT ALL SITES THROUGH SUNDAY. BY SUNDAY EVENING...NEXT SYSTEM STARTS TO AFFECT THE AREA AND WILL BRING IN SOME MVFR VIS AND CIGS WITH SOME LIGHT SNOW. THERE COULD BE A BRIEF PERIOD OF -SHSN OR FLURRIES AT KCMX/KSAW OVERNIGHT...BUT IT SHOULDN/T AFFECT VISIBILITIES OVERNIGHT. THESE CLOUDS SHOULD PUSH EAST ON SUNDAY MORNING AND JUST LEAVE SOME PASSING MID CLOUDS. DID PUT A MENTION OF SCATTERED LOW CLOUDS AT KSAW TOMORROW MORNING...SINCE THE MODELS ARE HINTING AT THAT POSSIBILITY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 421 PM EST SAT JAN 26 2013 HIGH PRESSURE CURRENTLY OVERHEAD WILL SHIFT EAST TONIGHT AND LEAD TO INCREASING SOUTHERLY WINDS...BUT EXPECT GUSTS TO REMAIN BELOW 25KTS. WINDS WILL REMAIN BELOW 25KTS THROUGH THE FIRST COUPLE OF DAYS OF THE UPCOMING WORK WEEK DUE TO WEAK PRESSURE GRADIENTS. A LOW MOVING THROUGH THE GREAT LAKES ON TUESDAY AND THEN INCREASING IN INTENSITY OVER EASTERN CANADA WILL PRODUCE INCREASING NORTHERLY WINDS TO 30KTS TUESDAY NIGHT INTO WEDNESDAY. THIS...COMBINED WITH COLDER AIR SURGING SOUTH...WILL LEAD TO FREEZING SPRAY FOR THE MIDDLE AND END OF THE WORK WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...ROLFSON AVIATION...07 MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1149 PM CST SAT JAN 26 2013 .UPDATE... ISSUED AT 845 PM CST SAT JAN 26 2013 OVER THE LAST FEW HOURS AREA OF OVERRUNNING RAIN HAS DEVELOPED FROM SOUTHERN KANSAS INTO N OK. THIS AREA SHOULD CONTINUE TO EXPAND INTO OUR CWA DURING THE PREDAWN HOURS AND EARLY SUNDAY AS ZONE OF ISENTROPIC LIFT STRENGTHENS AND EXPANDS NORTHEAST WITH INTENSIFYING LOW LEVEL JET. OVERALL...GOING FORECAST IS LOOKING EXCELLENT. BASED ON REGIONAL RADAR TRENDS AND LATEST HRRR AND NAM WE MAY BE BRINGING THE PRECIP INTO OUR AREA A BIT TOO FAST BUT IT WOULD APPEAR THAT DIFFERENCE WOULD ONLY BE ON THE ORDER OF AN HOUR OR TWO...AND HAVE MADE THIS VERY SUBTLE TWEEK TO HOURLY POP GRIDS FROM COU NORTH AT 06Z. GOING FORECAST FOR FREEZING LINE AT THE SURFACE IS ALSO STRONGLY SUPPORTED BY LATEST HI-RES GUIDANCE. WHILE ITS CERTAINLY POSSIBLE THAT SOME MINOR TWEEKS WILL BE REQUIRED ONCE RAIN AND SURFACE TEMP TRENDS BECOME A BIT MORE OBVIOUS DONT THINK I CAN IMPROVE UPON ANY OF THESE AT THIS TIME. GOING ADVISORY CERTAINLY DOES A NICE JOB OF HIGHLIGHTING GREATEST FREEZING RAIN THREAT IN OUR CWA. TRUETT && .SHORT TERM... ISSUED AT 330 PM CST SAT JAN 26 2013 (TONIGHT AND SUNDAY) MAIN ITEM OF INTEREST FOR THE NEXT 24 HOURS IS THE POTENTIAL FOR FREEZING RAIN AND ICE ACCUMULATIONS. THE PATTERN WILL BE PROGRESSIVE DURING THIS PERIOD AS AN UPPER TROF DIGS ALONG THE WEST COAST KICKING THE SOUTHWEST UPPER TROF NEWD INTO THE PLAINS TONIGHT AND THEN INTO THE UPPER MS VALLEY ON SUNDAY. IN THE PROCESS THE UPPER RIDGE CURRENTLY CENTERED THRU THE WRN PLAINS WILL SHIFT TO A POSITION INVOF THE MS RIVER BY 12Z SUNDAY AND THEN INTO THE OH VALLEY BY SUNDAY EVENING. IN THE PROCESS...THE SURFACE HIGH NOW CENTERED THRU IL WILL RETREAT EWD WITH A SWLY LLJ AND LOW LEVEL WAA COMMENCING IN ITS WAKE. THIS VEERING LOW LEVEL JET IS FORECAST TO TRANSPORT WARM MOIST AIR BACK INTO THE AREA OVERNIGHT INTO SUNDAY MORNING AND PROVIDE ASCENT FOR A PRECIPITATION EVENT. A FAIRLY EXTENSIVE SHIELD OF PRECIPITATION IS EXPECTED TO DEVELOP OVERNIGHT IN RESPONSE. THE MODELS ARE IN GENERAL AGREEMENT ON THE SCENARIO BUT IN ARE TRENDING A BIT SLOWER WITH THE ONSET OF RAIN. GIVEN THE UPPER RIDGE AXIS ALONG THE MS RIVER AT DAYBREAK SUNDAY...THE THREAT OF RAIN SHOULD REMAIN TO THE WEST OF THE MS RIVER TONIGHT...SPREADING EAST ON SUNDAY MORNING WITH PROGRESSION OF THE PATTERN. THERE WILL BE A BATTLE DURING THE EVENT BETWEEN THE ARRIVAL OF WARM/ABOVE FREEZING AIR AND THE ONSET AND SPREAD OF RAINFALL. COMPLICATING THIS IS THE LOWER SURFACE DEW POINTS WILL RESULT IN EVAPORATIVE COOLING WHICH MAY INITIALLY OFFSET THE WARMING...HOWEVER GIVEN THE STRENGTH OF WARMING...THE WARM AIR WILL OVERWHELM THE RESIDUAL COLD AIR ON THE BACKSIDE OF THE RETREATING HIGH ACROSS ERN MO AND WEST CENTRAL IL. TEMPS IN MID MO MAY BE ABOVE FREEZING BY THE TIME THE RAIN BEGINS LATE TONIGHT AND IN THE ST LOUIS AREA THEY WILL BE FLIRTING WITH THE FREEZING MARK FOR SEVERAL HOURS NEAR THE ONSET. THE COLD AIR WILL BE STRONGER AND REMAIN ENTRENCHED LONGER IN NE MO AND WEST CENTRAL IL WHERE ICE ACCUMULATIONS WILL AVERAGE .10 TO .15 INCHES. I HAVE EXPANDED THE FREEZING RAIN A BIT FURTHER SOUTH WHERE THERE COULD BE SOME DECENT GLAZING. BY EARLY AFTERNOON WARM AIR WILL COMPLETELY OVERSPREAD THE REGION WITH TEMPS SOARING. GLASS && .LONG TERM... ISSUED AT 330 PM CST SAT JAN 26 2013 (SUNDAY NIGHT THROUGH TUESDAY NIGHT) THE WARM SECTOR WILL COMPLETELY OVERSPREAD THE AREA SUNDAY NIGHT AS SOUTHERLY LOW LEVEL FLOW TRANSPORTS WARM AIR AND MOISTURE NEWD. THIS WILL RESULT IN A PERIOD OF WELL ABOVE NORMAL TEMPERATURES THROUGH TUESDAY AND MOST LIKELY SOME RECORDS WILL BE SET. THE SWLY FLOW ALOFT IS LARGELY VOID OF ANY WELL-DEFINED DISTURBANCES TO CONTRIBUTE TO LARGE SCALE ASCENT THROUGH MONDAY NIGHT. THUS ANY PRECIPITATION THREAT WILL INITIALLY BE LIGHT RAIN/DRIZZLE ON SUNDAY NIGHT WITH THE MOISTURE RETURN AND THEN SCATTERED SHOWERS OR THUNDERSTORMS WITH THE SWLY LLJ AXIS. PROGRESSION OF THE WRN U.S. LARGE SCALE POSITIVELY TILTED UPPER TROF INTO THE CENTRAL CONUS AND THE PASSAGE OF THE ASSOCIATED SURFACE COLD FRONT ON TUESDAY AND TUESDAY NIGHT SHOULD LEAD TO THE WIDESPREAD SHOWERS AND THUNDERSTORMS. SEVERE POTENTIAL WILL ULTIMATELY DEPEND ON THE AMOUNT OF INSTABILITY AS DEEP LAYER SHEAR WILL BE PLENTY STRONG TO SUPPORT ORGANIZED CONVECTION. (WEDNESDAY THROUGH SATURDAY) A DEEP LONGWAVE TROF WILL EVOLVE THRU THE ERN HALF OF THE CONUS DURING THIS PERIOD. THE COLD FRONT ON TUESDAY/TUESDAY NIGHT WILL BRING AN INITIAL SURGE OF COLD AIR...WITH A BIG PUSH OF ARCTIC AIR ON THURSDAY. FRIDAY APPEARS TO BE THE COLDEST DAY WITH WELL BELOW NORMAL TEMPERATURES...THEN THE ARCTIC RETREATS BY THE WEEKEND WITH WAA UNDERWAY AND WARMING TEMPS. GLASS && .AVIATION... ISSUED AT 1147 PM CST SAT JAN 26 2013 RAIN HAS DEVELOPED OVER KANSAS AND IS SLOWLY MAKING ITS WAY TO THE EAST AND NORTHEAST. LITTLE ADJUSTMENTS TO TIMING OF ONSET OF THE RAIN...WITH IT MOVING INTO KCOU BY 10Z...KSUS BY 12Z AND REST OF TAF SITES AROUND 13Z. STILL EXPECT IT TO BE ALL RAIN AT KCOU...BUT START OFF AS FZRA IN METRO AREA AND KUIN. TEMPS TO RISE ABOVE FREEZING BY 16Z...WHILE KUIN WILL NOT WARM UP TIL AROUND 18Z. 00Z MODEL RUNS KEEPING RAIN AROUND A BIT LONGER...SO WILL NOT SEE RAIN MOVE OUT OF KCOU TIL 19Z...METRO AREA TIL 22Z AND KUIN TIL 01Z MONDAY. AS FOR CIGS...TO DROP DOWN TO MVFR WHEN RAIN MOVES IN AND REMAIN MVFR FOR REST OF FORECAST PERIOD. EAST TO SOUTHEAST WINDS TO PERSIST THEN VEER TO THE SOUTH AND PICKUP AS WARM FRONT LIFTS NORTH OF TAF SITES. HAVE ADDED GUSTS NEAR 25KTS FOR KCOU AND KUIN FOR THIS AFTERNOON AS DECENT WINDS MIX DOWN TO THE SURFACE. SOME CONCERN ABOUT LLWS TONIGHT AFTER 00Z MON OVER CENTRAL AND NORTHEAST MO DUE TO DECENT LL JET...BUT CONFIDENCE IS LOW AND WILL LEAVE OUT OF TAFS FOR NOW. SPECIFICS FOR KSTL...RAIN HAS DEVELOPED OVER KANSAS AND IS SLOWLY MAKING ITS WAY TO THE EAST AND NORTHEAST. LITTLE ADJUSTMENTS TO TIMING OF ONSET OF THE RAIN...WITH IT MOVING INTO METRO AREA BETWEEN 12Z AND 13Z. STILL EXPECT IT TO START OFF AS FZRA IN METRO AREA WITH LIGHT ICE ACCUMULATION...BUT TEMPS TO RISE ABOVE FREEZING BY 16Z. 00Z MODEL RUNS KEEPING RAIN AROUND A BIT LONGER...SO WILL NOT SEE RAIN MOVE OUT OF METRO AREA TIL 22Z. AS FOR CIGS...TO DROP DOWN TO MVFR WHEN RAIN MOVES IN AND REMAIN MVFR FOR REST OF FORECAST PERIOD. EAST TO SOUTHEAST WINDS TO PERSIST THEN VEER TO THE SOUTH AND PICKUP AS WARM FRONT LIFTS NORTH OF KSTL BY 16Z. BYRD && .CLIMATE... ISSUED AT 334 PM CST THU JAN 24 2013 RECORD OR NEAR RECORD-BREAKING TEMPERATURES MAY BE POSSIBLE ON MONDAY AND TUESDAY. BELOW IS A TABLE OF RECORD HIGHS AND RECORD HIGH MINIMUMS FOR ARE THREE OFFICIAL CLIMATE STATIONS: ST. LOUIS (STL)...COLUMBIA (COU)...AND QUINCY (UIN): ST. LOUIS HIGH HIGH MINIMUM 1/2876 (1970)53 (1914) 1/2973 (2008)44 (1947) COLUMBIA HIGH HIGH MINIMUM 1/28 67 (2002) 53 (1914) 1/29 64 (2008) 44 (1938) QUINCY HIGH HIGH MINIMUM 1/28 63 (1914) 46 (1914) 1/29 63 (1914) 38 (1989) && .LSX WATCHES/WARNINGS/ADVISORIES... MO...FREEZING RAIN ADVISORY FROM 4 AM TO 9 AM CST SUNDAY FOR KNOX MO- MONROE MO-SHELBY MO. FREEZING RAIN ADVISORY FROM 6 AM TO NOON CST SUNDAY FOR LEWIS MO- LINCOLN MO-MARION MO-PIKE MO-RALLS MO. IL...FREEZING RAIN ADVISORY FROM 6 AM TO NOON CST SUNDAY FOR ADAMS IL- BROWN IL-CALHOUN IL-GREENE IL-JERSEY IL-MACOUPIN IL- MONTGOMERY IL-PIKE IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
233 AM CST SUN JAN 27 2013 .SHORT TERM...TODAY THROUGH TUESDAY. HERE COMES THE RAIN. SURFACE TEMPERATURES HAVE REMAINED ABOVE FREEZING THROUGH THE NIGHT AND WILL REMAIN THAT WAY THROUGH THE DAY...THUS NO THREAT FOR FREEZING RAIN IN OUR FORECAST AREA THIS MORNING. PRETTY SOLID BAND OF RAIN WILL CONTINUE TO PUSH TO THE NORTH THIS MORNING AND THROUGH MOST OF THE FORECAST AREA BY EARLY THIS AFTERNOON. A DEFINITIVE SOUTHERN EDGE WILL LIKELY EVEN CLEAR SOUTHEAST NEBRASKA BEFORE 6 AM BASED ON LATEST RAP HOURLY DATA. ONCE THE HEAVIER SHOWERS MOVE OUT...STRATUS WILL LIKELY PREVAIL FOR THE AFTERNOON WITH AREAS OF DRIZZLE MAINLY ALONG AND NORTH OF INTERSTATE 80...WHICH THEN PUSHES NORTHEAST OUT OF THE AREA THROUGH THE EVENING. THERE COULD BE SOME BRIEF CLEARING BEHIND THIS BY LATE EVENING. AT THAT POINT...BELIEVE WE WILL FOG BACK IN THROUGH DAYBREAK MONDAY...WITH THE LOW LEVEL MOISTURE NOT REALLY BEING SCRUBBED OUT. WINDS GO VERY LIGHT OR EVEN CALM IN MOST AREAS BY 09-12Z MONDAY...WITH BOTH MAV/MET GUIDANCE SUGGESTING WIDESPREAD FOG DEVELOPING...AND POSSIBLY DENSE IN MANY AREAS. THIS WOULD PROBABLY LINGER INTO EARLY MONDAY MORNING...AND WOULD NOT BE SURPRISED IF A DENSE FOG ADVISORY MAY EVENTUALLY BE NEEDED. OF SOME CONCERN WOULD BE SURFACE TEMPERATURES DROPPING TO NEAR OR BELOW FREEZING MONDAY MORNING ALONG AND NORTH OF I80...WHICH COULD RESULT IN SLICK ROADWAYS FOR THE MORNING COMMUTE. MONDAY IS A BIT OF A TRANSITION DAY WITH MUCH OF THE MID MISSOURI VALLEY IN BETWEEN SYSTEMS. THE SURFACE WARM FRONT MAY LIFT BACK TO THE NORTH TO NEAR I80 THROUGH THE DAY. MEANWHILE...THE NEXT TROUGH MOVING THROUGH THE NORTHERN ROCKIES SHOULD START TO SPREAD DEEPER MOISTURE INTO NORTHEAST NEBRASKA BY MONDAY AFTERNOON...BUT CERTAINLY MONDAY NIGHT. AT THE SAME TIME...AN ADVANCING COLD FRONT WILL ALSO BE USHERING IN COLDER AIR TO NORTHEAST NEBRASKA. SHOULD SEE RAIN MIX WITH AND CHANGE TO SNOW ACROSS NORTHEAST NEBRASKA...AND GIVEN THAT THIS IS OCCURRING AT NIGHT COULD PROBABLY EVEN SEEM SOME MINOR ACCUMULATIONS OF AN INCH UP THERE BY DAYBREAK TUESDAY. FURTHER SOUTH ALONG AND SOUTH OF I80...PRECIP POTENTIAL IS MORE MORE QUESTIONABLE...BUT WILL MAINTAIN SLIGHT CHANCE POPS THAT LINGER INTO TUESDAY AS WELL...BUT CERTAINLY COULD ALSO BE DRY ACROSS ALL AREAS BUT NORTHEAST NEBRASKA. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. A TRANSITION TO A COLDER ARCTIC AIR MASS WILL CONTINUE EARLY IN THE PERIOD WITH THE FIRST REINFORCING SHOT OF COLDER AIR OVERSPREADING THE AREA ON WEDNESDAY WITH BLUSTERY NORTHWEST WINDS. HIGHS WILL BE BACK IN THE UPPER TEENS NORTH TO UPPER 20S SOUTH...BUT COLDER FEELING WITH THE WINDS. THE GFS HAS HINTED AT SOME FLURRY POTENTIAL ACROSS NORTHEAST NEBRASKA AS H85 TEMPERATURES APPROACH THE DENDRITIC RANGE...BUT THE ECMWF IS STILL DRY. SECOND AND COLDER REINFORCING SURGE ARRIVES BY THURSDAY...AGAIN WITH CONTINUED NORTHWEST BLUSTERY CONDITIONS. EVEN COLDER TEMPS WELL WITHIN THE DENDRITIC RANGE WOULD SUGGEST SOME FLURRY POTENTIAL AGAIN WITH HIGHS EVEN COLDER IN THE LOWER TEENS NORTH TO MID 20S SOUTH...WITH WIND CHILLS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO ONCE AGAIN. SURFACE HIGH MOVES OVER THE AREA THURSDAY NIGHT RESULTING IN LOWS IN THE SINGLE DIGITS ONE MORE TIME. FRIDAY AND SATURDAY SHOULD BE TRANSITION DAYS BACK TO WARMER TEMPS AGAIN WEST WESTERLY FLOW...DRY CONDITIONS AND HIGHS BACK INTO THE MID TO UPPER 40S FOR THE WEEKEND. DEWALD && .AVIATION...06Z TAFS FOR KOFK...KLNK AND KOMA. DETERIORATING CONDITIONS ARE EXPECTED AS AREA OF RAIN MOVES INTO EASTERN NEBRASKA THIS MORNING. MVFR CIGS/VSBYS WITH INITIAL SURGE OF PRECIPITATION IN 08Z-11Z TIME FRAME WILL DECREASE TO IFR BY 12Z-14Z. RAIN WILL MOVE OUT OF AREA BY 18Z...BUT LINGERING LOW CLOUDS AND MVFR VSBYS ARE EXPECTED IN DRIZZLE AND FOG. A PERIOD OF VFR CONDITIONS IS POSSIBLE BETWEEN 21Z AND 02Z...BUT LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE WILL SET THE STAGE FOR IFR OR LOWER CIGS/VSBYS AS WINDS DECREASE AND FOG FORMS TOWARD END OF TAF PERIOD. DERGAN && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1147 PM CST SAT JAN 26 2013 .AVIATION...06Z TAFS FOR KOFK...KLNK AND KOMA. DETERIORATING CONDITIONS ARE EXPECTED AS AREA OF RAIN MOVES INTO EASTERN NEBRASKA THIS MORNING. MVFR CIGS/VSBYS WITH INITIAL SURGE OF PRECIPITATION IN 08Z-11Z TIME FRAME WILL DECREASE TO IFR BY 12Z-14Z. RAIN WILL MOVE OUT OF AREA BY 18Z...BUT LINGERING LOW CLOUDS AND MVFR VSBYS ARE EXPECTED IN DRIZZLE AND FOG. A PERIOD OF VFR CONDITIONS IS POSSIBLE BETWEEN 21Z AND 02Z...BUT LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE WILL SET THE STAGE FOR IFR OR LOWER CIGS/VSBYS AS WINDS DECREASE AND FOG FORMS TOWARD END OF TAF PERIOD. DERGAN && .PREV DISCUSSION... /ISSUED 331 PM CST SAT JAN 26 2013/ SHORT TERM...TONIGHT THROUGH TUESDAY SHORT TERM FORECAST CONCERNS WILL BE THE ASSOCIATED DETAILS WITH THE PRECIPITATION EVENT TONIGHT AND SUNDAY...THEN DRIZZLE AND FOG AS LIFT DECREASES LATER SUNDAY INTO SUNDAY NIGHT. POTENTIAL FOR LIGHT PRECIPITATION MONDAY IN SOUTHEAST NEB NEAR H85 FRONT AND IN THE NORTHEAST NEB WITH A COLD FRONT AND ACROSS THE FORECAST AREA INTO TUESDAY. THE SURFACE WARM FRONT IS LIFTING NORTH AND BRISK SOUTH WINDS HAVE WARMED TEMPERATURES INTO THE 40S AND 50S...WITH BEATRICE NEARLY REACHING 60. SURFACE DEWPOINTS ARE VARIABLE IN THE TEENS AND 20S. 3HR PRESSURE FALLS WERE NOTED ACROSS MUCH OF THE PLAINS IN RESPONSE TO LOWERING PRESSURE OVER THE EASTERN ROCKIES. PER VISIBLE SATELLITE AND METARS...LOW LEVEL STRATUS IS BEGINNING TO WORK NORTH AND THIS IS THE LEADING EDGE OF THE MID 30S DEWPOINTS. WATER VAPOR SATELLITE IMAGERY AND LIGHTNING DATA...SHOWED THE SHORTWAVE TROF HAD MOVED INTO THE SOUTHWEST U.S. BY MIDDAY AND THERE WERE LIGHTNING STRIKES OVER EASTERN ARIZONA. THIS WAVE WILL BE OUR WEATHER MAKER THROUGH SUNDAY. THE H9 JET IS FROM THE SOUTH AT 25 TO 35KT AND WILL CONTINUE TO INCREASE TO 35 TO 45KT OVER THE FORECAST AREA THROUGH 06Z. MEANWHILE...THE NOSE OF THE H85 50KT JET IS OVER SOUTHWEST KS. THETA-ADVECTION AND H7 OMEGA INCREASE ACROSS KANSAS THROUGH 06Z AND THEN ACROSS NEBRASKA INTO IOWA AND MISSOURI THROUGH 12Z. THERE ALSO IS SOME UPPER LEVEL JET SUPPORT BY 12Z. THE 4KM WRF/NAM/GFS/SREF/EC/RAP ARE SIMILAR IN HAVING THE PRECIPITATION OVERSPREADING THE FORECAST AREA FROM SOUTHWEST TO NORTHEAST MAINLY BETWEEN 08Z AND 14Z. REGARDING PRECIPITATION TYPE...WILL NEED TO MONITOR AREAS IN FAR NORTHEAST NEBRASKA AND PARTS OF WESTERN IOWA SHOULD PRECIPITATION BEGIN AS FREEZING RAIN. THE MODELS ARE NOT IN GOOD AGREEMENT WITH THE LOW LEVEL TEMPS. THE NAM SEEMS QUITE COOL...AND SEVERAL OF THE OTHER MODELS ARE A BIT WARMER. TRENDED WITH THE WARMER RAP TEMPERATURES VERSUS THE COOLER NAM TEMPS. WITH THE VERY MILD CONDITIONS THIS EVENING AND INCREASING CLOUDS AND STRONG SOUTH FLOW...THINK MOST LOCATIONS WILL BE ABOVE FREEZING WHEN THE PRECIPITATION STARTS...SO LEFT FREEZING MENTION ONLY IN THE FAR NORTHEAST ZONES. AS THE SHORTWAVE MOVES EAST...SO DOES THE PRECIPITATION AND LOOK FOR DRIZZLE AND FOG LATER SUNDAY AFTERNOON AND SUNDAY NIGHT. RAINFALL AMOUNTS LOOK TO VARY FROM 0.1 TO .4 OF AN INCH. THE COLD FRONT IS NEAR FALLS CITY BY 06Z SUNDAY NIGHT...HOWEVER THE LOW LEVEL MOISTURE DOES NOT GET SCOURED OUT. WITH THE WEAK FLOW OVERNIGHT DO MENTION FOG. WILL NEED TO WATCH FOR BELOW FREEZING TEMPERATURES AND FOG FOR THE MONDAY MORNING COMMUTE...AS THIS COULD CAUSE PROBLEMS. MONDAY...THERE IS WARM AIR ADVECTION ACROSS THE SOUTHERN CWA AND MAY SEE SOME LIGHT PRECIP. IN THE NORTHWEST PART OF THE FORECAST AREA...THERE IS A REINFORCING COLD FRONT SLOWLY MOVING SOUTHEAST ASSOCIATED WITH THE MID LEVEL TROF. THIS FRONT HAS SOME DECENT FRONTOGENESIS WITH IT AND MONDAY INTO TUESDAY COULD BRING SOME RAIN...A MIX AND THEN POSSIBLE A NARROW BAND OF LIGHT SNOW. IT IS INTERESTING THAT THERE IS SOME ELEVATED INSTABILITY WITH THIS BAND AND ALSO NEAR THE H85 FRONT IN SOUTHERN NEBRASKA MONDAY NIGHT. FOR NOW...TOP/EAX HAVE SOME TSRA MENTIONED IN THEIR CWA MONDAY NIGHT AND WE HAVE RAIN IN THE SOUTH AND A RAIN/SNOW MIX THEN ALL SNOW NORTH. TEMPERATURES ARE GOING TO BE A CHALLENGE EACH DAY AND HAVE HIGHS SUNDAY AND MONDAY IN THE 30S TO AROUND 40 FAR NORTH TO THE 50S SOUTH. TUESDAY HAVE HIGHS IN THE LOWER 30S NORTH TO UPPER 40S SOUTH. ZAPOTOCNY LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. THE UPPER LEVEL FLOW PATTERN WILL TRANSITION TO THE NORTHWEST DURING THIS PERIOD AND THE GLOBAL MODELS ARE IN PRETTY GOOD AGREEMENT ON THIS EVOLUTION. THE UPPER LEVEL TROUGH FOR MON/TUE WILL JUST BE EXITING THE REGION ON TUE NIGHT AND WILL LINGER SOME SCHC POPS FOR -SN IN THE SOUTH AS THIS EXITS...OTHERWISE THE EXTENDED PART OF THE FORECAST IS DRY. AN ARCTIC COLD FRONT WILL MOVE THROUGH THE FA ON WED NIGHT WHICH WILL LEAD TO MUCH COLDER HIGHS ON THU AND LOWS THU NIGHT. BUT LIKE RECENT COLD SURGES...THIS WILL BE GREATLY MODIFIED BY THE LACK OF SNOW COVER ACROSS THE FA. THUS WE ARE EXPECTING HIGHS IN THE TEENS/20S AND LOWS IN THE SINGLE DIGITS ABOVE ZERO. THE UPPER LEVEL RIDGE TO THE WEST WILL SHIFT A BIT EAST ON ON FRI/SAT AND ALLOW FOR SOME DOWN-SLOPE AND PACIFIC AIR TO SPILL BACK INTO THE FA. NORMAL HIGHS WITH NO SNOW COVER BY THE END OF THE PERIOD ARE IN THE LOWER TO MID 40S...AND WE SEE NO REASON WE CAN`T GET NEAR THESE NUMBERS. THUS WE HAVE GONE ABOVE THE CLIMO HEAVY MOS GUIDANCE FOR THE END OF THE PERIOD. BOUSTEAD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
459 AM EST SUN JAN 27 2013 .SYNOPSIS... HIGH PRESSURE WILL LINGER OVER THE AREA TODAY BEFORE MOVING OFFSHORE ON MONDAY. A STRONG COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY AND CROSS THE REGION WEDNESDAY NIGHT. HIGH PRESSURE WILL GRADUALLY BUILD IN FROM THE NORTHWEST THURSDAY THROUGH SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 435 AM SUNDAY...LOW STRATUS CONTINUE TO MOVE ACROSS THE AREA AND NOW COVERS MOSTLY THE SOUTHWESTERN HALF OF THE CWA. SOME CLEARING IS NOW TAKING PLACE ACROSS THE FAR NORTHEASTERN COUNTIES. SKY COVER FORECAST WILL REMAIN TRICKY THIS MORNING AS MOISTURE IS TRAPPED BENEATH A STRONG LOW-LEVEL INVERSION. LATEST RAP OUTPUT SHOWS MOST OF THE LOW CLOUDS DISSIPATING BY MID MORNING. THE DAY SHOULD AVERAGE OUT AT PARTLY CLOUDY. HIGH TEMPERATURES WILL AGAIN BY CHILLY WITH LOWER TO MIDDLE 40S AREA-WIDE AS AXIS OF COOL HIGH PRESSURE RIDGE SETTLES OVER THE CAROLINAS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... AS OF 435 AM SUNDAY...MID-LEVEL MOISTURE INCREASES FROM THE WEST TONIGHT AS A WEAK SHORTWAVE EMBEDDED IN THE NORTHWEST FLOW ALOFT MOVES ACROSS THE REGION. THE GFS SPITS OUT A BIT OF QPF OVER THE FAR NORTHERN COUNTIES WHILE THE NAM12...CANADIAN AND ECMWF KEEP ANY QPF TO THE NORTH OF OUR REGION THROUGH DAYBREAK MONDAY. WILL CONTINUE TO KEEP THE CWA DRY BUT WILL INDICATE MID AND HIGH LEVEL CLOUDINESS OVERNIGHT. THIS CLOUDINESS SHOULD HOLD MINIMUM TEMPERATURES BETWEEN 30 AND 35 DEGREES FOR MOST AREAS. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 3 AM SUN...A WEAK SHORTWAVE WILL RIDE OVER THE UPPER RIDGE MON AND CROSS NORTH CAROLINA FROM W TO E MON AFTN AND MAY PRODUCE SOME SPRINKLES OR LIGHT SHOWERS ACROSS NORTHERN SECTIONS...MAINLY NORTH OF HWY 264. SOME UNCERTAINTY IN MAX TEMPS MON WITH CLOUDS AND PCPN BRINGING EVAP COOLING ENHANCING IN-SITU DAMMING INLAND BUT SLY FLOW TRIES TO DEVELOP AS HIGH PRES SLIDES OFF THE COAST. COULD SEE HIGHS ONLY AROUND 50S FAR INLAND BUT APPROACHING 60 SRN COASTAL SECTIONS. SURFACE RIDGE WILL REMAIN OFF THE COAST MON NIGHT...ALLOWING WINDS TO VEER S-SW AND BRING DEWPOINTS BACK INTO THE 40S ACROSS THE REGION WHICH COULD BRING AREAS OF FOG ACROSS THE REGION EARLY TUE. GRADIENTS WILL TIGHTEN TUES/TUES NIGHT WITH RIDGE HOLDING STRONG OFF THE COAST AND A STRONG UPPER LEVEL TROUGH WITH ATTENDANT SURFACE COLD FRONT DIGGING ACROSS THE CENTRAL/SOUTHERN MISSISSIPPI VALLEY. LOW LEVEL THICKNESSES INCREASE ABOUT 30M TUE WITH MAX TEMPS CLIMBING INTO THE UPPER 60S TO LOW 70S INLAND AND LOW TO MID 60S ACROSS THE OBX...WITH LOWS TUES NIGHT ONLY FALLING INTO THE 50S. STRONG WAA PERSISTS ON WED WITH A STRENGTHENING LOW LEVEL JET BRINGING TEMPS INTO THE LOW TO MID 70S INLAND TO MID 60S OBX. IT WON`T TAKE MUCH MIXING TO BRING WIND GUSTS TO AROUND 30 MPH OR STRONGER WED AFTERNOON WITH 40-50 KTS WINDS JUST 1000-2000FT AGL AND GRADIENT WINDS COULD REACH WIND ADVISORY CRITERIA ALONG COASTAL SECTIONS. THERE REMAINS SOME DIFFERENCES AMONG THE MODELS WITH THE TIMING OF THE FRONT. THE GFS IS FASTEST BRINGING SHOWERS INTO THE REGION LATE WED AFTERNOON AND THE FRONT ACROSS THE REGION WED EVENING WHILE THE PREFERRED ECMWF IS SLOWER HOLDING THE HEAVIER PCPN OFF UNTIL WED EVENING AND THE FRONT ACROSS THE REGION AFTER MIDNIGHT. KEPT MENTION OF THUNDER OUT OF THE GRIDS THIS MORNING AS MODELS INDICATE LESS THAN 100 J/KG CAPE THROUGH PEAK HEATING THOUGH STRONG UNIDIRECTIONAL WIND SHEAR WILL BE IN PLACE AND COULD SEE STRONG WIND GUSTS IN HEAVIER SHOWERS. THE SYSTEM WILL BE PUSHING ACROSS THE REGION FAIRLY QUICKLY LIMITING THE AMOUNT OF QPF EXPECTED THOUGH WE COULD SEE A QUICK 1/2 TO 3/4" WED NIGHT. TEMPS WILL LIKELY REMAIN IN THE 60S MUCH OF WED NIGHT AHEAD OF THE FRONT AND ONLY DROPPING TO AROUND 50 BY DAYBREAK AFTER FROPA. CAA RAMPS UP EARLY THU AND EXPECT MAX TEMPS TO OCCUR IN THE MORNING WITH HIGHS MAINLY IN THE M50S...THEN SLOWLY DECREASE THROUGH THE AFTERNOON. THURS/THURS NIGHT WILL SEE TEMPS BACK NEAR NORMAL WITH HIGHS IN THE MID/UPPER 50S AND LOWS IN THE LOW/MID 30S. SHORTWAVE ENERGY WILL ROTATE AROUND THE BASE OF A DIGGING UPPER TROUGH FRI WITH GUIDANCE SUGGESTING PRECIP CLIPPING THE NE ZONES. HAVE POPS JUST BELOW SLIGHT CHANCE FOR NOW GIVEN UNCERTAINTY IN THE EXTENDED. THE SHORTWAVE WILL ALSO PROVIDE A REINFORCING SHOT OF COLD AIR TO THE REGION. LOW LEVEL THICKNESSES AND 850 MB TEMPS FALL TO -9 TO -12C FRI AND EXPECT HIGHS IN THE 40S. SURFACE RIDGE BUILDS SE ACROSS THE REGION SAT WITH ZONAL FLOW ALOFT...AND TEMPS IN THE MID/UPPER 40S. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... SHORT TERM /TODAY AND TONIGHT/... AS OF 1255 AM SUNDAY...BASED ON CURRENT SATELLITE IMAGERY AND SURFACE OBSERVATIONS...WILL GO A BIT MORE NEGATIVE ON THE TAFS THROUGH THE OVERNIGHT HOURS. WITH LOW LEVEL MOISTURE TRAPPED BENEATH A STRONG INVERSION...THINK THE IFR/LIFR CEILINGS WILL CONTINUE ALONG WITH PATCHES OF FOG. VFR WILL RETURN BY MORNING AS COLUMN DRIES WITH GOOD MIXING TAKING PLACE. LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 330 AM SUN...A SHORTWAVE TROUGH RIDES OVER UPPER RIDGING CENTERED OVER FLA MON WHICH COULD BRING LIGHT SHOWER WITH PERIODS OF SUB VFR CONDITIONS ACROSS RTES...MAINLY NORTH OF US 264. SOUTH TO SOUTHWEST FLOW BRINGS RISING DEWPOINTS MON NIGHT AND COULD SEE AREAS OF FG/ST DEVELOP BRINGING IFR OR LOWER EARLY TUES. A STRONG COLD FRONT APPROACHES TUES NIGHT AND WED WITH A STRENGTHENING LOW LEVEL JET AND LOW LEVEL WIND SHEAR COULD BE AN ISSUE EARLY WED FOLLOWED BY STRONG WIND SOUTH TO SOUTHWEST GUSTS UPWARDS OF 25-30 KTS WED AFTERNOON. SOME TIMING DIFFERENCES WITH THE FRONT WED NIGHT BUT A PERIOD OF HEAVY SHOWERS WITH STRONG WIND GUSTS AND SUB VFR CONDITIONS LIKELY AHEAD OF THE FRONT. VFR CONDITIONS EXPECTED THU AS CAA RAMPS UP BRINGING WEST WINDS GUSTING TO AROUND 20-25 KTS. && .MARINE... SHORT TERM /TODAY AND TONIGHT/... AS OF 440 AM SUNDAY...AREA OBSERVING PLATFORM SHOWING A BIT OF A SURGE WORKING DOWN FROM THE NORTH WITH WINDS GENERALLY IN THE 15 TO 20 KNOT RANGE NORTH OF CAPE LOOKOUT AND OVER THE SOUNDS. SEAS HAVE BUILT TO 7 FEET AT THE BUOY 13 MILES EAST OF OREGON INLET AS OF 4 AM. HAVE EXTENDED THE SCA FOR THE CENTRAL WATERS THROUGH ABOUT MIDDAY TO ALLOW TIME FOR THESE SEAS TO SUBSIDE AS THE SURFACE RIDGE OF HIGH PRESSURE WORKS ITS WAY SOUTH. WINDS BECOMING 10 KNOTS OR LESS TONIGHT WITH THE RIDGE AXIS ALONG THE CAROLINA/VIRGINIA COAST. LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 330 AM SUN...SURFACE RIDGE WILL SHIFT OFFSHORE MON WITH WINDS VEERING SOUTH TO SOUTHWEST AND INCREASING DURING THE AFTERNOON AS A SYSTEM PASSES TO THE NORTH...PEAKING AROUND 10-20 KT MON NIGHT WHILE SEAS BUILD TO 2-4 FT. SLIGHT SLACKENING OF THE WINDS TUE...GRADIENT WILL INCREASE TUES NIGHT INTO WED AS A STRONG COLD FRONT APPROACHES FROM THE WEST. MODELS IN GOOD AGREEMENT DEVELOPING STRONG SCA CONDITIONS LATE WED AFTERNOON AND SEVERAL MODELS EVEN BRING A SHORT WINDOW GALES JUST AHEAD OF THE FRONT WED EVENING. SOME SPECULATION ON JUST HOW MUCH MIXING WILL OCCUR OVER THE COOLER NEAR SHORE WATERS BUT GALES QUITE LIKELY NEAR THE GULF STREAM WITH A 60+ KT LOW LEVEL JET IN PLACE. WAVEWATCH HIGHER WITH SEAS AS A RESULT OF STRONGER WINDS AND BUILDS SEAS TO 8-12 FT WED AFTER NOON THROUGH WED NIGHT. SLIGHT TIMING DIFFERENCES AMONG THE MODELS WITH FROPA WITH FASTER MODELS BRINGING IT THROUGH WED EVENING THOUGH A MAJORITY OF MODEL CONSENSUS PUSHING THE FRONT THROUGH AFTER MIDNIGHT. WINDS SHIFT TO WEST TO NORTHWEST AFTER FROPA WITH WINDS AND SEAS GRADUALLY SUBSIDING THROUGH THE DAY THURSDAY. WAVEWATCH DROPS SEAS BELOW 6 FT AROUND MIDNIGHT THU NIGHT. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR AMZ152- 154. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...SK AVIATION...CTC/SK MARINE...CTC/SK
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 AM EST SUN JAN 27 2013 .SYNOPSIS... COLD AND DRY HIGH PRESSURE WILL HOLD OVER THE AREA TODAY. AN UPPER LEVEL DISTURBANCE WILL PASS NORTHEASTWARD THROUGH THE REGION TONIGHT THROUGH MONDAY MORNING. THE SURFACE HIGH WILL MOVE OFF THE COAST LATE MONDAY...FOLLOWED BY A WARM SOUTHWEST FLOW INTO THE REGION THROUGH MIDWEEK. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 310 AM SUNDAY... THROUGH SUNRISE...THE MAIN CONCERN ARE THE PATCHES OF DENSE FOG THAT HAVE DEVELOPED ACROSS PORTIONS OF OUR CWA INCLUDING THE TRIANGLE REGION. WE SUSPECT THAT LINGERING GROUND MOISTURE AND PATCHES OF ICE COVER FROM FRIDAYS STORM HAVE HELPED INITIATE THE DENSER PATCHES OF FOG. NOTED THAT THE HRRR CAPTURED THIS FOG PRETTY WELL...AND SHOWS IT CONTINUING THROUGH AROUND 12Z OR SO. GIVEN THE LIMITED NATURE OF THE 1/4 MILE VSBY REPORTS...FOR NOW WE HAVE THIS COVERED WITH AN SPS AND WILL MONITOR AS THE MORNING PROGRESSES. FOR THE DAYTIME TODAY AFTER FOG BURNS OFF...EXPECT LOW-IMPACT WEATHER AS THE S/W RIDGE CURRENTLY OVER THE MS VALLEY DRIFTS EAST TOWARD US AND THE SFC RIDGE REMAINS OVER THE CAROLINAS. DESPITE FORECAST SOUNDINGS DEPICTING A COOLER BL TODAY COMPARED TO YESTERDAY`S OBSERVED SOUNDING...EXPECT MORE SUNSHINE THAN YESTERDAY WHICH SHOULD HELP TEMPS CLIMB A FEW DEGREES HIGHER THAN YESTERDAY... RESULTING IN HIGHS AROUND 40 NORTH TO 46 SOUTH. FOR TONIGHT..THE MAIN CONCERN IS EVOLVING PRECIP POTENTIAL. THE MIDLEVEL RIDGE AXIS IS PROGGED TO SET UP OVER THE SOUTHEAST AND WILL INITIATE WAA ACROSS OUR AREA THAT WILL TAKE PLACE ABOVE THE SHALLOW COOLER NEAR-SFC LAYER. MODELS ARE GENERALLY DEPICTING THE MORE SIGNIFICANT SYNOP SCALE LIFT AND MOISTURE TRANSPORT OCCURRING TO OUR NORTH CLOSER TO A S/W TROUGH THAT WILL BE MOVING ACROSS THE MIDWEST REGION. THE GFS IS THE MOST GENEROUS REGARDING QPF ACROSS OUR AREA OVERNIGHT...WHILE OTHER MODELS KEEP MOST IF NOT ALL OF THE QPF NORTH OF THE VA/NC STATE LINE. IF LIGHT PRECIP DOES MATERIALIZE ACROSS OUR CWA LATER TONIGHT...STILL THINK WE HAVE A DECENT CHANCE TO SEE SOME LIGHT AND BRIEF FROZEN/FREEZING PRECIP AT THE ONSET GIVEN WET BULB COOLING AND LINGERING COLD NEAR-SFC TEMPS. FORECAST SOUNDINGS FOR THE OVERNIGHT PERIOD DEPICT THE AFOREMENTIONED GRADUAL WAA AND MOISTURE INCREASE FROM THE MID-LEVELS DOWN...YET THERE REMAINS PLENTY OF DRY AIR BETWEEN 750-900 MB WHICH RESULTS IN WET BULB TEMPS BELOW FREEZING FOR A SIGNIF LAYER BELOW 850MB. IF LIFT WAS STRONGER AND PRECIP RATES HEAVIER...I WOULDN`T BE SURPRISED IF WE EVEN SAW A QUICK P-TYPE TRANSITION FROM S TO IP TO FZRA THEN RAIN WHILE THE COLUMN SATURATES AND WARMS. FOR NOW WILL KEEP LOW-END POPS ACROSS OUR NORTHERN ZONES CLOSER TO THE TRIAD AND VA BORDER BEGINNING AFT 3 AM. WHILE THE PRECIP RISK STILL LOOKS LOW...IF IT INDEED EVOLVES...THERE WILL BE A CHANCE FOR A FEW LOCALIZED SLICK SPOTS MONDAY MORNING AT THE ONSET...WHICH WOULD MAINLY IMPACT ELEVATED SURFACES AND BRIDGES...BEFORE TEMPS RISE ABOVE FREEZING AFT SUNRISE. WHILE CONFIDENCE IN PRECIP OCCURRING IS TOO LOW ATTM TO WARRANT ANY SORT OF ADVISORIES...WILL CONTINUE TO MENTION IN THE HWO THE POTENTIAL FOR LIGHT FZRA IF PRECIP DOES INDEED EVOLVE. EXPECT LOWS FROM AROUND 30 NORTH TO LOWER 30S SOUTH. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...AS OF 310 AM SUNDAY... MONDAY AND MONDAY NIGHT: THE CENTER OF ANOTHER ARCTIC HIGH...1033 MB CENTERED NEAR CLEVELAND AT 07Z/27TH...WILL HAVE MODIFIED AND DRIFTED OFF THE NC COAST BY MONDAY...THOUGH SIGNIFICANT LINGERING IN-SITU COLD AIR DAMMING EFFECTS WILL REMAIN. AFTER THE EARLY MORNING PRECIPITATION REFERENCED ABOVE...THIS IN-SITU WEDGE WILL MAINTAIN A LOW OVERCAST AND EVEN SOME CONTINUED PATCHES OF DRIZZLE...WITH TEMPERATURES WELL BELOW WHAT NWP WOULD SUGGEST. LOCAL THICKNESS/ TEMPERATURE RESEARCH THAT ACCOUNTS FOR CLOUD COVERAGE AND HEIGHT SUGGESTS TEMPERATURES WILL HOLD IN THE 40S OVER THE PIEDMONT...TO 50-55 DEGREES ACROSS THE SOUTHERN TIER. WHILE SOME PARTIAL CLEARING WILL BE POSSIBLE LATE IN THE DAY OVER THE SANDHILLS...THE STRATUS LAYER WILL EXPAND AND LOWER...WITH AREAS OF DENSE FOG POSSIBLE... SHORTLY AFTER NIGHTFALL. HIGHS 45 TO 55...WITH A MINIMAL DIURNAL FALL INTO THE 39 TO 46 DEGREE RANGE OVERNIGHT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 310 AM SUNDAY... A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION FROM A PAIR OF RIDGES ALONG EACH COAST...WITH A HIGHLY AMPLIFIED BUT PROGRESSIVE TROUGH IN BETWEEN. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH THE EASTERN US/CENTRAL NC WED-WED NIGHT. IT WILL TURN MILDER IN ADVANCE OF THE SYSTEM TUE-WED...THOUGH THIS WARMING WILL BE TEMPERED OVER THE PIEDMONT BY CONTINUED IN-SITU WEDGE INFLUENCE AND ASSOCIATED STRATUS MOISTURE TRAPPED BY A STRONG SUBSIDENCE INVERSION ALOFT. HIGHS TUE FROM AROUND 60 DEGREES NW TO AROUND 70 SE...THEN ABOUT A CATEGORY MILDER IN A BREEZY SOUTHWESTERLY LOW LEVEL FLOW...BUT WITH INCREASING DEEP LAYER MOISTURE/MULTI-LAYERED OVC...ON WED. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES NORTH OF HIGHWAY 64 FRI MORNING...GIVEN THE EXPECTED S/W TRACK ACROSS SOUTHERN VA. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. && .AVIATION /06Z SUNDAY THROUGH WEDNESDAY/... AS OF 105 AM SATURDAY... A LOCALIZED AREA OF DENSE FREEZING FOG WITH IFR/LIFR CONDITIONS CONTINUES ATTM GENERALLY SOUTH OF A LINE FROM KHBI-KRDU-KLHZ FOR ABOUT 40 MILES. SIMILAR CONDITIONS CURRENTLY EXIST ALONG AND EAST OF THE I-95 CORRIDOR FROM NEAR KFAY TO THE NC/VA LINE. RAP FORECAST SOUNDINGS SUGGEST THIS WILL CONTINUE THROUGH AT LEAST 10Z WITH PERHAPS SOME MODEST IMPROVEMENT BETWEEN 10-14Z. OUTSIDE OF THIS FOG...EXPECT VFR CONDITIONS. AFT 14Z...LOOK FOR VFR CONDITIONS THROUGH THE REST OF THE TAF FORECAST PERIOD WITH PERHAPS SOME SCT CU OR STRATOCU BETWEEN 3-5K FT THIS MORNING AND EARLY...THEN ADDITIONAL HIGH CLOUDS LATE...AND WINDS AOB 10 KT. A WEAK MID-UPPER DISTURBANCE WILL APPROACH AND CROSS THE REGION LATE SUNDAY NIGHT INTO EARLY MONDAY. THIS SYSTEM AND THE AVAILABLE MOISTURE IN THE ATMOSPHERE MAY TRIGGER A FEW PATCHES OF LIGHT PRECIPITATION ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. TEMPERATURES WILL BE CLOSE TO OR SLIGHTLY BELOW FREEZING...SO POCKETS OF FREEZING RAIN OR FREEZING DRIZZLE MAY OCCUR. CONFIDENCE LEVEL OF SEEING FREEZING PRECIPITATION IS ABOUT 33 PERCENT. IF FREEZING PRECIPITATION WERE TO OCCUR...IT WOULD AFFECT THE TRIAD TERMINALS AND POSSIBLY KRDU AND KRWI. OTHERWISE EXPECT MVFR CEILINGS WITH THIS SYSTEM MONDAY INTO MONDAY NIGHT. A BRIEF IMPROVEMENT IN AVIATION CONDITIONS EXPECTED TUESDAY THOUGH IT WILL BECOME BREEZY A WITH SW WIND GUSTING 20-25 MPH IN THE AFTERNOON. A STRONG COLD FRONT WILL APPROACH CENTRAL NC TUESDAY NIGHT AND CROSS THE AREA LATE WEDNESDAY INTO WEDNESDAY NIGHT. EXPECT CONTINUED BREEZY CONDITIONS AHEAD AND IMMEDIATELY BEHIND THE FRONT WITH A CHANCE OF MVFR CEILINGS WED-WED NIGHT ALONG WITH SCATTERED SHOWERS. IMPROVING WEATHER CONDITIONS ARE ANTICIPATED FOR THU... THROUGH IT IS EXPECTED TO REMAIN BREEZY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NP NEAR TERM...NP SHORT TERM...MWS LONG TERM...MWS AVIATION...NP/WSS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
105 AM EST SUN JAN 27 2013 .SYNOPSIS... COLD AND DRY HIGH PRESSURE WILL HOLD OVER THE AREA THROUGH SUNDAY. AN UPPER LEVEL DISTURBANCE WILL PASS NORTHEASTWARD THROUGH THE REGION SUNDAY NIGHT THROUGH MONDAY MORNING. THE SURFACE HIGH WILL MOVE OFF THE COAST LATE MONDAY... FOLLOWED BY A WARM SOUTHWEST FLOW INTO THE REGION THROUGH MIDWEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 925 PM SATURDAY... THROUGH TONIGHT: INTERESTING FORECAST TONIGHT AS PATCHES OF FOG HAVE DEVELOPED OVER THE STATE... WHILE TWO AREAS OF STRATUS -- ONE JUST SW OF RALEIGH AND A LARGER ONE OVER THE INTERIOR CENTRAL/NRN COASTAL AREA -- SLOWLY DRIFT TOWARD THE WEST WITHIN THE PREVAILING LIGHT NEAR-SURFACE FLOW FROM THE ENE. THIS AFTERNOON`S LARGE-SCALE COMPUTER MODELS DID NOT PICK UP ON THIS WELL AT ALL... BUT THE RAPID-UPDATE FINE-SCALE MODELS SUCH AS THE HRRR ARE DEPICTING IT FAIRLY WELL... SHOWING THE STRATUS OVER EASTERN NC CONTINUING TO DRIFT WESTWARD THROUGH CENTRAL NC OVERNIGHT. THE NEW 12KM NAM RUN SHOWS THE NEXT POINT OF CONCERN -- THE BATCH OF HIGHER-BASED CLOUDS OVER EAST-CENTRAL VA -- ADVECTING SOUTHWARD OVERNIGHT AS THE SURFACE HIGH -- LOCATED OVER NORTH CENTRAL OH AT 00Z -- DRIFT EASTWARD TONIGHT AND NOSING MORE STRONGLY TO THE SSE INTO NC. WE`RE ALREADY SEEING SOME LOWER SURFACE DEW POINTS STARTING TO WORK SOUTHWARD FROM VA TOWARD NC... WHICH SHOULD LIMIT THE LIFETIME AND EXTEND OF FOG THROUGH THE NIGHT... BUT NEVERTHELESS A FEW SPOTS WILL SEE VSBYS UNDER A MILE FOR A COUPLE OF HOURS... EXACERBATED IN SPOTS BY THE LINGERING MOIST GROUND AND REMAINING PATCHY SNOW/ICE/SLEET ACCUMULATIONS... WITH GENERALLY LIGHT WINDS. HAVE ADDED THIS FOG TO THE FORECAST... AS WELL AS BEEFING UP THE CLOUD COVER ESPECIALLY IN THE EASTERN AND NORTHERN CWA. THE RISK OF BLACK ICE REMAINS TONIGHT INTO SUNDAY MORNING AS TEMPS WILL BOTTOM OUT BELOW FREEZING TOWARD MORNING. DESPITE SLIPPING DEW POINTS LATE TONIGHT... WITH CLOUDS IN PLAY... HAVE NUDGED LOWS UPWARD SLIGHTLY TO 23-28. -GIH SUNDAY...S/W RIDGE DRIFTS EWD ACROSS THE LOWER OH AND TN VALLEYS. THIS FEATURE WILL MAINTAIN A SURFACE RIDGE ACROSS THE CAROLINAS. THE AIR MASS ASSOCIATED WITH THE SURFACE RIDGE WILL SLOWLY MODIFY. THUS...SHOULD SEE AFTERNOON TEMPS ABOUT 3-4 DEGREES WARMER THAN CURRENT AFTERNOON TEMPS. MAX TEMPS SUNDAY IN THE LOW-MID 40S. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 305 PM SATURDAY... SUNDAY NIGHT...SURFACE RIDGE AXIS SLIDES SE...PLACING CENTRAL NC IN THE RETURN FLOW SIDE OF THE HIGH...INITIATING A LOW LEVEL WARM AIR ADVECTION REGIME. W-SW FLOW ALOFT WILL ADVECT MOISTURE INTO THE REGION...AHEAD OF AN UPPER LEVEL LOW PRESSURE SYSTEM THAT WILL SKIRT WELL W-NW OF OUR REGION. THUS ANTICIPATE INCREASING CLOUDINESS SUNDAY NIGHT. MODEL GUIDANCE CONTINUES TO PAINT PATCHY PRECIP ACROSS MAINLY THE NW AND FAR NORTHERN SECTION OF THE CWA OVERNIGHT SUNDAY NIGHT THROUGH MID MORNING MONDAY. MODEL LIFT RATHER ANEMIC THOUGH...MAINLY CENTERED ALOFT. ATMOSPHERE BELOW WHILE AIR MASS ABOVE 4000FT WILL UNDERGO DECENT WARMING...AIR MASS NEAR THE SURFACE WILL STILL RETAIN SOME OF ITS RESIDUAL COOL DRY AIR. SURFACE WET BULB TEMPS REMAIN BELOW FREEZING THROUGH 12Z MONDAY. THUS...WHAT PRECIP FALLS THROUGH THE COLUMN WILL LEAD TO SOME COOLING OF THE TEMP PROFILE NEAR THE SURFACE. MODEL TEMP PROFILE AND PARTIAL THICKNESSES SUGGEST MAIN P-TYPE FZRA AND/OR RAIN. EVEN IF FZRA/FZDZ WERE TO OCCUR...IT WILL BE SPOTTY AND VERY LIGHT IN NATURE DUE TO LACK OF ORGANIZED LIFT IN THE LOW-MID LEVELS. THUS NOT ANTICIPATING WIDESPREAD TRAVEL ISSUES EARLY MONDAY MORNING BUT CANNOT RULE OUT THE POTENTIAL FOR A SLICK BRIDGE OR TWO. IF/WHEN IT BECOMES MORE CERTAIN PATCHY FZRA/FZDZ WILL OCCUR...A WINTER WEATHER ADVISORY MAY BE NECESSARY. MIN TEMPS NEAR 30 TO THE LOWER 30S. -WSS MONDAY AND MONDAY NIGHT: THE CENTER OF ANOTHER ARCTIC HIGH...1030 MB CENTERED NEAR CHICAGO AT 19Z/26TH...WILL HAVE MODIFIED AND DRIFTED OFF THE NC COAST BY MONDAY...THOUGH THE LINGERING IN-SITU CAD EFFECTS WILL REMAIN. AFTER THE EARLY MORNING PRECIPITATION REFERENCED ABOVE...THIS IN-SITU WEDGE WILL MAINTAIN A LOW OVERCAST...WITH TEMPERATURES AOB WHAT NWP WOULD SUGGEST. WHILE SOME PARTIAL CLEARING WILL BE POSSIBLE LATE IN THE DAY OVER THE SANDHILLS...LOW STRATUS AND FOG - SOME DENSE - WILL ENVELOP CENTRAL NC SHORTLY AFTER NIGHTFALL. HIGHS 45 TO 55...WITH A MINIMAL DIURNAL FALL INTO THE 39 TO 46 DEGREE RANGE OVERNIGHT. -MWS && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 245 PM SATURDAY... A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION FROM A PAIR OF RIDGES ALONG EACH COAST...WITH A HIGHLY AMPLIFIED BUT PROGRESSIVE TROUGH IN BETWEEN. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM...THROUGH THE EASTERN US/CENTRAL NC WED-WED NIGHT. IT WILL ACCORDINGLY TURN QUITE MILD IN ADVANCE OF THE SYSTEM ON TUE...THOUGH TEMPERED A BIT OVER THE PIEDMONT WHERE STRATUS AND FOG WILL BE SLOW TO LIFT AND SCATTER. THIS STRATUS MOISTURE WILL BE TRAPPED BY A STRONG SUBSIDENCE INVERSION ALOFT AND RESULT IN RENEWED STRATUS DEVELOPMENT OVERNIGHT TUE...WITH TEMPERATURES APT TO RISE OVERNIGHT FROM LATE EVENING LOWS IN THE LOWER 50S ON AVERAGE. MILDER YET...TO WARM ON WED...IN STRONG SOUTHWESTERLY FLOW IN ADVANCE OF THE AFOREMENTIONED FRONTAL ZONE...WITH HIGHS WITHIN 5 DEGREES OF 70 WEST TO EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE FROM A THIRD OF AN INCH OVER THE COASTAL PLAIN TO THREE QUARTERS OF AN INCH OR SO OVER THE WESTERN PIEDMONT. STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS A GOOD PROBABILITY OF GOOD RADIATIONAL COOLING CONDITIONS. HOWEVER...MEDIUM RANGE GUIDANCE DOES INDICATE A S/W TROUGH ALOFT AND ACCOMPANYING CIRRUS SHIELD MAY OVERSPREAD THE MIDDLE ATLANTIC REGION AT THAT TIME...SO WILL NOT FORECAST - YET - THE UPPER TEENS THAT PROJECTED LOW LEVEL THICKNESSES WOULD SUGGEST. && .AVIATION /06Z SUNDAY THROUGH WEDNESDAY/... AS OF 105 AM SATURDAY... A LOCALIZED AREA OF DENSE FREEZING FOG WITH IFR/LIFR CONDITIONS CONTINUES ATTM GENERALLY SOUTH OF A LINE FROM KHBI-KRDU-KLHZ FOR ABOUT 40 MILES. SIMILAR CONDITIONS CURRENTLY EXIST ALONG AND EAST OF THE I-95 CORRIDOR FROM NEAR KFAY TO THE NC/VA LINE. RAP FORECAST SOUNDINGS SUGGEST THIS WILL CONTINUE THROUGH AT LEAST 10Z WITH PERHAPS SOME MODEST IMPROVEMENT BETWEEN 10-14Z. OUTSIDE OF THIS FOG...EXPECT VFR CONDITIONS. AFT 14Z...LOOK FOR VFR CONDITIONS THROUGH THE REST OF THE TAF FORECAST PERIOD WITH PERHAPS SOME SCT CU OR STRATOCU BETWEEN 3-5K FT THIS MORNING AND EARLY...THEN ADDITIONAL HIGH CLOUDS LATE...AND WINDS AOB 10 KT. A WEAK MID-UPPER DISTURBANCE WILL APPROACH AND CROSS THE REGION LATE SUNDAY NIGHT INTO EARLY MONDAY. THIS SYSTEM AND THE AVAILABLE MOISTURE IN THE ATMOSPHERE MAY TRIGGER A FEW PATCHES OF LIGHT PRECIPITATION ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. TEMPERATURES WILL BE CLOSE TO OR SLIGHTLY BELOW FREEZING...SO POCKETS OF FREEZING RAIN OR FREEZING DRIZZLE MAY OCCUR. CONFIDENCE LEVEL OF SEEING FREEZING PRECIPITATION IS ABOUT 33 PERCENT. IF FREEZING PRECIPITATION WERE TO OCCUR...IT WOULD AFFECT THE TRIAD TERMINALS AND POSSIBLY KRDU AND KRWI. OTHERWISE EXPECT MVFR CEILINGS WITH THIS SYSTEM MONDAY INTO MONDAY NIGHT. A BRIEF IMPROVEMENT IN AVIATION CONDITIONS EXPECTED TUESDAY THOUGH IT WILL BECOME BREEZY A WITH SW WIND GUSTING 20-25 MPH IN THE AFTERNOON. A STRONG COLD FRONT WILL APPROACH CENTRAL NC TUESDAY NIGHT AND CROSS THE AREA LATE WEDNESDAY INTO WEDNESDAY NIGHT. EXPECT CONTINUED BREEZY CONDITIONS AHEAD AND IMMEDIATELY BEHIND THE FRONT WITH A CHANCE OF MVFR CEILINGS WED-WED NIGHT ALONG WITH SCATTERED SHOWERS. IMPROVING WEATHER CONDITIONS ARE ANTICIPATED FOR THU... THROUGH IT IS EXPECTED TO REMAIN BREEZY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...WSS/MWS LONG TERM...MWS AVIATION...NP/WSS
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1256 AM EST SUN JAN 27 2013 .SYNOPSIS... STRONG HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST TONIGHT AND SUNDAY...THEN SLIDE OFFSHORE MONDAY AND TUESDAY. A COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY AND CROSS THE REGION WEDNESDAY NIGHT. HIGH PRESSURE WILL GRADUALLY BUILD IN FROM THE NORTHWEST THURSDAY THROUGH SATURDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1245 AM SUNDAY...LATEST 11-3.9 MICRON SATELLITE IMAGERY SHOWS WIDESPREAD LOW STRATUS CONTINUE TO ADVECT AND GROW OVER MOST OF EASTERN NORTH CAROLINA WITH SHALLOW MOISTURE TRAPPED BENEATH STRONG INVERSION. THE LATEST RAP HAS A DECENT HANDLE ON THIS CLOUD COVER AND WILL INCREASE CLOUDS TO BE A MOSTLY OVERCAST NIGHT. NO OTHER MAJOR CHANGES TO THE CURRENT FORECAST AT THIS TIME. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... AS OF 225 PM SAT...MOSTLY SUNNY SKIES EXPECTED SUNDAY AS THE STRONG HIGH PRES BUILDS SE AND ACROSS THE REGION LATE. CONT N/NE LOW LVL FLOW WILL KEEP TEMPS BELOW NORMAL WITH HIGHS RANGING FROM AROUND 40 NE CST TO MID/POSS A FEW UPR 40S SW. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... AS OF 3 PM SAT...SURFACE RIDGE WILL SHIFT OFFSHORE SUN NIGHT WITH WINDS SHIFTING TO SE BY SUNRISE. A WEAK SHORTWAVE WILL RIDE OVER THE UPPER RIDGE MON AND CROSS NORTH CAROLINA FROM W TO E MON AFTN AND MAY PRODUCE SOME SPRINKLES ACROSS NORTHERN SECTIONS. HAVE INTRODUCED SLIGHT CHANCE POPS FOR AREAS ALONG AND NORTH OF HWY 64. UPPER RIDGE CENTERED OVER FLORIDA WILL PERSIST INTO TUES NIGHT. TEMPS WILL BE NEAR CLIMO SUN NIGHT INTO MON...LOWS IN THE LOW 30S INLAND TO LOW 40S OBX...AND HIGHS IN THE MID 50S. SURFACE RIDGE WILL REMAIN OFF THE COAST MON AND MON NIGHT...ALLOWING WINDS TO VEER S-SW AND BRING DEWPOINTS BACK INTO THE 40S ACROSS THE REGION. GRADIENT WILL TIGHTEN TUES/TUES NIGHT WITH RIDGE HOLDING STRONG OFF THE COAST AND A STRONG UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT DIGGING PUSHING EAST INTO THE CENTRAL/SOUTHERN MISSISSIPPI VALLEY. HIGHS TUES WILL BUILD INTO THE LOW 70S INLAND TO NEAR 60 ACROSS THE OBX...WITH LOWS TUES NIGHT ONLY FALLING INTO THE 50S. SW SURFACE FLOW WILL PERSIST ON WED WITH HIGHS AGAIN IN THE 70S WITH DEWPOINTS BUILDING INTO THE LOW/MID 50S. A STRONG COLD FRONT WILL PUSH EAST THROUGH EASTERN NC ON WED NIGHT INTO THURS MORNING. AT THIS TIME...INSTABILITY LOOKS TO REMAIN WELL OFFSHORE AND HAVE REMOVED MENTION OF THUNDER WITH THIS FORECAST PACKAGE. HAVE INCREASED POPS TO 50 PERCENT WED NIGHT GIVEN GOOD MODEL AGREEMENT BETWEEN LATEST MEDIUM RANGE GUIDANCE. WITH THE COLD FRONT CROSSING EARLY THURS MORNING...EXPECT MAX TEMPS TO OCCUR IN THE MORNING AND SLOWLY DECREASE AS THE DAY PROGRESSES DUE TO STRONG WNW CAA. THURS/THURS NIGHT WILL SEE TEMPS BACK NEAR NORMAL WITH HIGHS IN THE MID/UPPER 50S AND LOWS IN THE LOW/MID 30S. SHORTWAVE ENERGY WILL ROTATE AROUND THE BASE OF A DIGGING UPPER TROUGH FRI WITH GUIDANCE SUGGESTING PRECIP CLIPPING THE NE ZONES. HAVE POPS JUST BELOW SLIGHT CHANCE FOR NOW GIVEN UNCERTAINTY IN THE EXTENDED. THE SHORTWAVE WILL ALSO PROVIDE A REINFORCING SHOT OF COLD AIR TO THE REGION. LOW LEVEL THICKNESSES AND 850 MB TEMPS FALL TO -9 TO -12C FRI AND WENT WITH BLEND BETWEEN MEX/ECMWF MOS WITH HIGHS IN THE UPPER 40S TO LOW 50S SOUTH TO LOW 40S NORTH...ALTHOUGH THESE TEMPS MAY BE TOO WARM AND MAY BE REDUCED 4-5F WITH LATER FORECAST PACKAGES. SURFACE RIDGE BUILDS SE ACROSS THE REGION SAT WITH ZONAL FLOW ALOFT...AND TEMPS IN THE MID/UPPER 40S. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... SHORT TERM /THROUGH SUNDAY/... AS OF 1255 AM SUNDAY...BASED ON CURRENT SATELLITE IMAGERY AND SURFACE OBSERVATIONS...WILL GO A BIT MORE NEGATIVE ON THE TAFS THROUGH THE OVERNIGHT HOURS. WITH LOW LEVEL MOISTURE TRAPPED BENEATH A STRONG INVERSION...THINK THE IFR/LIFR CEILINGS WILL CONTINUE ALONG WITH PATCHES OF FOG. VFR WILL RETURN BY MORNING AS COLUMN DRIES WITH GOOD MIXING TAKING PLACE. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 315 PM SAT...MAINLY VFR CONDITIONS EXPECTED THROUGH WED. BOUNDARY LAYER BEGINS TO MOISTEN TUES AS WINDS SHIFT S/SW. CANNOT RULE OUT EARLY MORNING FOG ACROSS TAF SITES SHOULD WINDS SUFFICIENTLY DECOUPLE. SW WINDS WILL GUST UPWARDS OF 20-25 KTS WED AFTERNOON. A STRONG COLD FRONT WILL CROSS THE REGION WED NIGHT INTO THURS. MAY SEE REDUCED VSBYS/CEILINGS WITH THE FRONTAL PASSAGE. && .MARINE... SHORT TERM /THROUGH SUNDAY/ AS OF 1255 AM SUNDAY...FIRST SIGNS ON CAA SURGE SHOWING UP AT THE CHESAPEAKE LIGHT WITH WINDS GUSTING TO 20 KNOTS. PER PREVIOUS FORECAST...COULD SEE A PERIOD OF 6 FOOT SEAS OVER THE OUTER PERIPHERY OF THE CENTRAL MARINE ZONES THROUGH THE EARLY MORNING HOURS AS THE AREA OF PRESSURE RISES WORKS TO THE SOUTH. AS THE CENTER OF THE HIGH BUILDS CLOSER SUNDAY NE WINDS WILL GRAD DIMINISH AND SHLD BE IN THE 5 TO 10 KT RANGE BY EVENING. SEAS WILL SUBSIDE TO 2 TO 4 FT SUN AFTN. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 315 PM SAT...SURFACE RIDGE WILL SHIFT OFFSHORE MON WITH WINDS VEERING SOUTH TO SOUTHWEST BUT WITH SPEEDS 10 KNOTS OR LESS. SEAS WILL BE 1-3 FT THROUGH TUES. GRADIENT WILL INCREASE LATE TUES INTO WED BETWEEN HIGH OFFSHORE AND COLD FRONT APPROACHING FROM THE WEST. SW WINDS WILL BUILD TO 20-25 KT LATE WED WITH THE FRONTAL PASSAGE. SEAS WILL BUILD 3-5 FT TUES NIGHT THEN 5-8 FT WED/THURS. EXPECT SCA HEADLINES WILL BE NEEDED FOR INCREASED WINDS AND SEAS WED THROUGH THURS. ONLY MINOR ADJUSTMENTS TO LATEST WAVEWATCH III GUIDANCE. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ152- 154. && $$ SYNOPSIS...RF NEAR TERM...CTC SHORT TERM...RF LONG TERM...DAG AVIATION...CTC/DAG MARINE...CTC/RF/DAG
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
351 AM CST SUN JAN 27 2013 .VERY SHORT TERM...TODAY AND TONIGHT. FORECAST CONFIDENCE FOCUS SQUARELY ON PRECIPITATION TYPE/TIMING WITH POTENT SHORT WAVE APPROACHING FROM THE SOUTHWEST. ENHANCED CLOUDS IN PACIFIC MOISTURE PLUME AHEAD OF WAVE WRAPPING AROUND MULTIPLE VORTICITY MAXIMA NOTED ON WATER VAPOR LOOPS OVER SW NEBRASKA...EASTERN KANSAS AND EXTREME SE COLORADO...WITH A PRONOUNCED DRY SLOT BEHIND PLUME FROM NRN MEXICO INTO KANSAS. PRECIPITATION MOVES IN LATE THIS MORNING/EARLY AFTERNOON INTO THIS EVENING WITH A BAND OF PRECIPITATION ASSOCIATED WITH STRONG LAYER FRONTOGENETIC RESPONSE TO 850-700MB WARM AIR ADVECTION AHEAD OF THE WAVE. MODEL SOUNDINGS SHOW INITIAL MOISTENING NEEDED TO SATURATE DRY LAYER BELOW 750 MB...WITH EVAPORATIVE COOLING TAKING THE WET BULB TEMP TO 0C IN THE COLUMN FOR A PERIOD OF ALL SNOW TO START...THEN WARMING ALOFT AND LOSS OF ICE CRYSTALS WITH THE DGZ DRYING OUT AS PRONOUNCED DRY SLOT PUSHING NEWD ACROSS KANSAS ON WATER VAPOR LOOPS INTRODUCES LIQUID INTO THE SUB-0C LAYER BELOW 900 MB TO THE SURFACE. THIS BRINGS SLEET AND EVENTUALLY FREEZING RAIN INTO THE MIX...GOING TO ALL LIGHT FREEZING RAIN AND THEN RAIN. CONSENSUS QPF AMOUNTS AND TEMPERATURE TRENDS BRINGS ICE ACCUMULATIONS BETWEEN 0.10 AND 0.20...WITH SNOW AROUND 0.5 SOUTH...WITH 1 TO 1.5 NORTH WITH LATER SWITCH TO A MIX. WHILE THIS WILL BE A WINTRY MESS...AMOUNTS STAY WITHIN ADVISORY GUIDELINES. WILL MONITOR DURING EVENT AS NAM SOUNDINGS WERE SHOWING A MORE PROLONGED PERIOD OF SNOW...WHILE RAP LEANED MORE TOWARDS FZRA TO RAIN WITH VERY LITTLE SNOW. SURFACE TEMPS WARM ENOUGH FOR ALL RAIN BY 06Z MONDAY..EXCEPT FOR AN AREA IN THE FAR NRN CWA SO WILL KEEP START AND END TIMES AS IS FOR ADVISORY. WITH WARMING THROUGH THE DAY AND LITTLE DROP OFF TONIGHT...WENT WITH LATE HIGHS IN THE LOW TO MID 30S..AND LOWS ONLY A FEW DEGREES COOLER. MONDAY - CONFIDENCE...MEDIUM SHORTWAVE AXIS ACROSS THE CWA EARLY ON WITH THIS WAVE WHISKING EAST PRETTY QUICK. BASED ON CONSENSUS OF MODELS WILL LIMIT POPS TO JUST THE MORNING HOURS. BRIEF PERIOD OF SURFACE/850 RIDGING TAKING HOLD. MONDAY NIGHT - CONFIDENCE...MEDIUM STRENGTHENING 40-50 KNOT SW LOW LEVEL JET AIMS AT THE CWA. DECENT MOISTURE ADVECTION NOTED. ECMWF HAS QPF MAX NEAR WI/IL BORDER WHILE GEM HAS IT MORE ACROSS THE CWA. NOT IMPRESSED WITH BUFKIT ELEVATED CAPE OR LAPSE RATES SO WILL HOLD OFF ON THUNDER MENTION FOR NOW. DID NUDGE POPS UP A BIT MORE THOUGH. TUESDAY - CONFIDENCE...MEDIUM MODELS TAKE SURFACE LOW VICINITY OF NE IA/SW WI AND RACE IT NORTHEAST THROUGH THE DAY. THIS WILL DRAG A COLD FRONT ACROSS SRN WI...BUT BEFORE FRONT ARRIVES...PLENTY OF MILD AIR IN PLACE. 925 TEMPS IN THE 10-12C RANGE ON THE ECMWF/GFS...WHILE THE NAM IS MUCH QUICKER TO BRING THE FRONT THROUGH. GOING WITH THE CONSENSUS OF THE ECMWF/GFS WILL HAVE TEMPS INTO THE 50S FOR THE SE CWA. ADDED A CHANCE OF THUNDER IN THE FAR SE DUE TO PREFRONTAL SOUNDINGS REVEALING ELEVATED INSTABILITY. THERMODYNAMICS LOOKING BETTER TO OUR SOUTH AND SOUTHEAST PER TRENDS IN CWASP. SWODY3 GENERAL DOES CLIP OUR SE AS WELL. WEDNESDAY - CONFIDENCE...MEDIUM LOW LEVEL COLD ADVECTION WITH MID LEVEL TROUGH AXIS SWINGING ACROSS. PRESSURE GRADIENT FAIRLY TIGHT AND WITH DECENT MIXING IN LOW LEVELS EXPECT NW WINDS TO BE ON THE GUSTY SIDE. SO A STARK CONTRAST TO THE MILD CONDITIONS OF TUESDAY. ECWMF A BIT SLOWER ON THE COLD ADVECTION...SEEING A 5-7 DEGREE DIFFERENCE WITH 925 TEMPS. DRY SLOT STILL IN PLACE THROUGH MIDDAY THEN A LITTLE MORE MOISTURE EXPECTED. WILL GO WITH THE SLIGHT CHANCE OF SNOW SHOWERS AS DEPICTED BY ALLBLEND POPS. THURSDAY - CONFIDENCE...MEDIUM COLDER YET WITH 925 TEMPS -20 TO -24C WHICH SUGGESTS SINGLE DIGIT HIGH TEMPS FOR MUCH OF THE CWA. ALLBLEND SHOWING 10-15 BUT THAT MAY BE TOO WARM. MIXED IN SOME COLDER NUMBERS FROM THE CONSRAW TO BRING TEMPS DOWN A BIT CLOSER TO THE 925 SCHEME. FRIDAY - CONFIDENCE...MEDIUM ECMWF/GFS AGREE THAT CORE OF COLDEST AIR SHIFTS EAST WITH LOW LEVEL WARM ADVECTION GETTING UNDERWAY AHEAD OF THE NEXT TROUGH. FRIDAY NIGHT AND SATURDAY - CONFIDENCE...MEDIUM COMBO OF WARM ADVECTION AND PASSAGE OF SURFACE/850 TROUGH BRINGS SHSN CHANCES THIS PERIOD. NOT LOOKING LIKE MUCH AT THIS POINT. ECMWF MUCH MORE AGGRESSIVE ON DEGREE OF COLD ADVECTION IN THE WAKE OF THE FRONT SATURDAY AFTERNOON/EVENING. && .AVIATION/12Z TAFS/...VFR CONDITIONS WILL DETERIORATE QUICKLY TO MVFR WITH PCPN MOVING INTO KMSN AROUND 17Z-18Z...KUES 18Z-19Z AND KMKE AND KENW AROUND 20Z...THEN FALLING TO IFR AND HOLDING THROUGH THE REMAINDER OF THE FORECAST. PCPN SHOULD START OUT AS LIGHT SNOW...MIXING WITH SLEET AND THEN FREEZING RAIN...GOING OVER TO ALL RAIN AS TEMPERATURES WARM. PERIOD OF FREEZING RAIN WILL BE SHORTER AT KMKE AND KENW AS TEMPERATURES WILL RISE ABOVE FREEZING SOONER WITH SE WINDS. && .MARINE...COMING SOON. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT CST TONIGHT FOR WIZ062-063-067>069. WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO MIDNIGHT CST TONIGHT FOR WIZ059-060-064>066-070>072. WINTER WEATHER ADVISORY FROM NOON TODAY TO 3 AM CST MONDAY FOR WIZ046-047-056-057. WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 3 AM CST MONDAY FOR WIZ051-052-058. LM...SMALL CRAFT ADVISORY FROM NOON TODAY TO 4 AM CST MONDAY FOR LMZ643>646. && $$ TODAY/TONIGHT AND AVIATION/MARINE...REM MONDAY THROUGH SATURDAY...COLLAR
AREA FORECAST DISCUSSION...CORRECTED
NWS LA CROSSE WI
344 AM CST SUN JAN 27 2013 CORRECTED INITIALS AT BOTTOM OF PRODUCT .SHORT TERM...TODAY THROUGH TUESDAY NIGHT 344 AM CST SUN JAN 27 2013 MAIN FORECAST CONCERNS ARE ON 2 MIXED PRECIPITATION EVENTS... TODAY/TONIGHT AND MONDAY NIGHT/TUESDAY. CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING ACROSS THE PACIFIC NORTHWEST INTO THE SAN FRANSISCO AREA...A FAIRLY POTENT SHORTWAVE OVER EASTERN COLORADO...AND RIDGING BUILDING DOWNSTREAM OF THIS SHORTWAVE FROM ARKANSAS NORTH INTO MINNESOTA. TROPOPAUSE ANALYSIS SHOWED A 100-120KT JET NEAR 250MB ACROSS MUCH OF THE WESTERN GREAT LAKES...PLACING MUCH OF IOWA IN THE FAVORABLE UPPER DIVERGENCE LEFT ENTRANCE REGION. THIS FORCING... COMBINED WITH AN UPPER LEVEL MOISTURE PLUME OUT OF THE EASTERN PACIFIC AHEAD OF THE COLORADO SHORTWAVE AS SEEN ON WATER VAPOR... RESULTING IN WIDESPREAD MID/HIGH CLOUDS OVER THE FORECAST AREA. THESE CLOUDS COMBINED WITH A SOUTHERLY BREEZE HAS ALLOWED TEMPERATURES TO HOLD STEADY OR CLIMB SLOWLY OVERNIGHT. DEWPOINTS ARE STILL QUITE DRY...THOUGH...IN THE LOW TEENS. THIS LOW LEVEL DRY AIR SHOWS UP ON 00Z SOUNDINGS FROM DVN...MPX AND GRB. TO THE SOUTHWEST...RADAR SHOWED AN AREA OF PRECIPITATION FROM WESTERN NEBRASKA INTO NORTHWEST MO. A COUPLE OF FEATURES ARE AT WORK PRODUCING THE PRECIPITATION. FIRST IS THE DPVA DOWNSTREAM OF THE COLORADO SHORTWAVE. SECOND IS A LOW LEVEL JET TRANSPORTING GULF OF MEXICO MOISTURE NORTHWARD THROUGH THE SOUTHERN AND CENTRAL PLAINS. 850MB VWP AND PROFILER DATA SHOWED 30-50 KT SOUTHWEST WINDS FROM TEXAS INTO KS...AND EVEN ALL THE WAY UP INTO OUR FORECAST AREA. GOES PRECIPITABLE WATER IMAGERY SHOWED VALUES AROUND 1 INCH IN ST JOSEPH MO. THIS LOW LEVEL JET WAS ALSO TRANSPORTING WARM AIR NORTHWARD... NOTED BY A RAP SOUNDING AT KLSE SHOWING AN 850MB AND 900MB TEMP AROUND 4C. THIRD WAS LOW TO MID LEVEL FRONTOGENESIS OCCURRING ALONG A SURFACE WARM FRONT NEAR I-70 IN KS. LASTLY...WATER VAPOR SHOWED A NOTICEABLE DRY SLOT ACCOMPANYING THE SHORTWAVE...FROM NEW MEXICO INTO CENTRAL KANSAS. MODEL PREFERENCES/TRENDS FOCUS IS ALL ON THE POTENT SHORTWAVE IN EASTERN COLORADO. STRENGTH...MODELS CONTINUE TO VARY...WITH THE 27.00Z GFS AND CANADIAN LOOKING THE MOST POTENT...THE 26.12Z ECMWF THE WEAKEST AND THE 27.00Z UKMET/NAM IN-BETWEEN. GIVEN THE APPEARANCE OF THE SHORTWAVE ON WATER VAPOR...HAVE LEANED MORE TOWARDS THE GFS/CANADIAN SOLUTION. IN ADDITION...THERE HAS BEEN A TREND OVER THE PAST FEW DAYS FROM ALL MODELS TO BE STRONGER. THE STRENGTH IS CRITICAL AS A STRONGER WAVE ALLOWS WARMER AIR TO GET PULLED NORTH VERSUS THE WEAKER WAVE SOLUTIONS. TRACK...ANOTHER TREND IS FOR THE SHORTWAVE TO TRACK FARTHER NORTH...NOW LOOKING TO GO THROUGH CENTRAL MN AT 00Z MON VERSUS THROUGH THE FORECAST AREA SEEN YESTERDAY. THIS ALSO HAS A HUGE IMPACT...SINCE IT SENDS THE DPVA FORCED PRECIPITATION FARTHER NORTH. IN ADDITION...GIVEN THAT WE HAVE A STRONGER WAVE...THE DRY-SLOT POTENTIAL TO IMPACT PRECIPITATION IS GREATER FOR OUR FORECAST AREA. DETAILS OF THE FORECAST TODAY AND TONIGHT... NO MATTER WHAT SOLUTION IS FOLLOWED...285-300K ISENTROPIC LIFT PROGS SUGGEST THE FORECAST AREA WILL SEE PRECIPITATION...ESPECIALLY IN THE 18Z TODAY - 06Z TONIGHT WINDOW AS HAS BEEN PREVIOUSLY FORECAST. THUS 100 PERCENT CHANCES ARE IN ORDER. PRECIPITATION CURRENTLY IN KANSAS SHOULD SPREAD SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA IN THE 15-21Z WINDOW. PRECIPITATION THEN DIMINISHES AFTER 06Z WEST TO EAST AS THE SHORTWAVE LIFTS INTO LAKE SUPERIOR...YIELDING SUBSIDENCE FROM BOTH DPVA AND ISENTROPIC DESCENT. GIVEN THE PREFERENCE FOR THE STRONGER SHORTWAVE SOLUTION...SOME CHANGES ARE NEEDED TO THE FORECAST: 1. THERE ARE STRONG INDICATIONS THAT THE CURRENT PRECIPITATION AREA...AS IT LIFTS NORTHEAST...IS GOING TO SPLIT INTO TWO DUE TO THE DRY-SLOT. ONE HEAVIER QPF AREA WILL HEAD THROUGH SOUTHEAST MN INTO NORTHERN WISCONSIN...ASSOCIATED WITH DPVA/FRONTOGENESIS ACCOMPANYING THE SHORTWAVE. THE OTHER HEAVIER QPF AREA HEADS EAST TOWARDS CHICAGO...SUPPORTED BY THE BETTER 850MB MOISTURE TRANSPORT. HAVE ADJUSTED THE QPF FORECAST TO SHOW THIS SPLIT. NOTE THAT THERE ARE INDICATIONS OF A THIRD QPF AREA AFTER 06Z...IMPACTING SOUTHERN PORTIONS OF THE AREA. THIS IS TIED TO LOW LEVEL FRONTOGENESIS WITH A SURFACE LOW AND WARM FRONT. 2. PRECIPITATION TYPE...EXTREMELY SENSITIVE! INITIAL WARM AIR WILL RESULT IN FREEZING RAIN/SLEET. THEN...UNDER THE HEAVIER QPF AREA HEADING NORTH...DYNAMIC AND EVAPORATIVE COOLING SHOULD KEEP THE BULK OF IT AS SNOW OR PERHAPS A LITTLE SLEET MIXED IN. JUST USING 850MB TEMPS AS A PROXY...PROGS FROM THE GFS/CANADIAN DEPICT THE DYNAMIC COOLING IMPACT WELL. SOUTH OF THE NORTHERN HEAVIER QPF AREA...WARM AIR SHOULD GET PULLED NORTH...ALLOWING MORE FOR A SLEET AND FREEZING RAIN SITUATION SOUTH OF I-90. EVENTUALLY THIS IS ALL GOING TO TRANSITION TO A RAIN/DRIZZLE IN THE EVENING HOURS DUE TO THE DRY SLOT SCOURING OUT THE ICE...WITH LIFT STILL OCCURRING BELOW. THE QUESTION IS IF THIS RAIN/DRIZZLE IS GOING TO BE FREEZING...SINCE WARMER SURFACE AIR SHOULD ALSO ADVECT NORTH AS THE SURFACE WARM FRONT APPROACHES. ALLOWED PRECIPITATION TO CHANGE OVER TO RAIN IN THE FAR SOUTH...PER GFS/REGIONAL CANADIAN PROGS. GIVEN THE COLD ROAD TEMPERATURES...THE RAIN/DRIZZLE MAY STILL FREEZE ON THE THEM. IN SUMMARY...THE WARNINGS MAY BE DIFFICULT TO VERIFY. THE NORTHERN HEAVIER QPF AREA MAY ONLY RESULT IN 3-5 INCHES OF SNOW AT ANY ONE LOCATION. MEANWHILE...THE AMOUNT OF FREEZING RAIN/DRIZZLE IS PERHAPS 1/10 TO AT MOST 2/10 INCH. SLEET ACCUMULATIONS ARE MOST LIKELY ON THE SOUTHERN EDGE OF THE NORTHERN HEAVIER QPF AREA...AND MAY ONLY END UP BEING A FEW TENTHS. HOWEVER...GIVEN THAT THIS IS A MESSY SITUATION AND WARNINGS ARE ALREADY POSTED...ALONG WITH THE EXTREME SENSITIVE NATURE TO THE WARM LAYER ALOFT...WILL GIVE THEM A CHANCE AND LET THEM RIDE. LASTLY...AS THE PRECIPITATION COMES TO AN END LATER TONIGHT... SUBSIDENCE WILL TRAP IN A LOT OF LOW LEVEL MOISTURE. SURFACE WINDS ARE LIGHT...YIELDING A FAVORABLE SCENARIO FOR FOG DEVELOPMENT. HAVE MAINTAINED AREAS OF FOG. IF THERE IS ANY DENSE FOG DEVELOPMENT...IT WOULD HAPPEN ACROSS THE HIGHER TERRAIN ALONG/SOUTH OF I-90. LATER SHIFTS MAY NEED TO ISSUE DENSE FOG ADVISORIES. MONDAY THROUGH TUESDAY NIGHT... ATTENTION RE-FOCUSES TO THE WEST WITH THE WEST COAST U.S. TROUGH. MODELS REMAIN IN GOOD AGREEMENT DIGGING A DEEP TROUGH WHICH PROGRESSES EASTWARD DURING THIS PERIOD. BY 12Z WEDNESDAY...THE AXIS EXTENDS FROM MINNESOTA INTO TEXAS. AS THIS TROUGH MOVES INTO THE AREA TUESDAY NIGHT...925/850MB TEMPS BEGIN TO PLUMMET...WITH BOTH FALLING TO -8 TO -14C BY 12Z WEDNESDAY. FURTHER COOLING TAKES PLACE HEADING INTO THE LONG TERM PERIOD BELOW. PRIOR TO THIS COLD ADVECTION...27.00Z ECMWF/GFS/CANADIAN/UKMET SHOW A SHORTWAVE EJECTING OUT OF THE TROUGH MONDAY AFTERNOON THROUGH MONDAY NIGHT ACROSS THE CENTRAL PLAINS. 27.00Z NAM WAS A MAJOR OUTLIER HANDLING THIS SHORTWAVE AND WILL NOT MENTION. THIS SHORTWAVE LEADS TO A SURFACE LOW WHICH DEEPENS AND REACHES EASTERN IOWA BY 12Z TUESDAY. EXPECTING A DRY MONDAY...BUT CLOUDY WITH MORNING FOG...DUE TO SUBSIDENCE AGAIN TRAPPING IN LOW LEVEL MOISTURE. AGAIN...MAY HAVE SOME DENSE FOG. SHOULD BE A WARM DAY COMPARED TO WHAT WE HAVE SEEN LATELY. AS THE LOW APPROACHES MONDAY NIGHT...LOW LEVEL LIFT AND ISENTROPIC LIFT INCREASES...RESULTING IN LIGHT PRECIPITATION. THERE IS A WARM LAYER ALOFT...BETWEEN 4-7C...BUT SURFACE TEMPERATURES IN THE EVENING COULD COOL DOWN BELOW FREEZING. NO ICE IS PRESENT EITHER. THIS SETS UP A POSSIBLE FREEZING RAIN SITUATION. HOWEVER...IT LOOKS TO BE BRIEF BECAUSE AS THE LOW APPROACHES... SURFACE TEMPERATURES WARM ABOVE FREEZING. IN FACT...BY 12Z...THE 27.00Z ECMWF HAS PLATTEVILLE AS WARM AS 53F. HAVE NOT GONE THAT WARM...BUT DID WARM THAT AREA UP FOR A HIGH ON TUESDAY IN THE UPPER 40S. SOME LINGERING LIGHT PRECIPITATION CONTINUES INTO TUESDAY MORNING...THEN THE DRY SLOT WITH THE SHORTWAVE PASSAGE SHOULD CLEAR THE PRECIP OUT. THUS...CHANCES OF PRECIPITATION ARE HIGHEST IN THE 06-18Z TUESDAY WINDOW. BEST CHANCES OF FREEZING RAIN TOO ARE IN THE NORTHWEST THIRD OF THE FORECAST AREA. ALSO TO NOTE...ADDED AREAS OF FOG ACROSS THE FORECAST AREA MONDAY NIGHT INTO TUESDAY MORNING...DUE TO LOW LEVEL MOISTURE STILL TRAPPED AND LIGHT WINDS. THIS TOO COULD BE A TIME PERIOD REQUIRING DENSE FOG ADVISORIES. HEADING INTO TUESDAY NIGHT... A SECONDARY COLD FRONT ASSOCIATED WITH THE LOW LOOKS TO CROSS THE AREA. KEPT A SMALL CHANCE OF SNOW SHOWERS WITH THIS FRONT. .LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT 344 AM CST SUN JAN 27 2013 27.00Z ECMWF/GFS/CANADIAN/UKMET AND ECMWF ENSEMBLES ARE IN REALLY GOOD AGREEMENT THROUGH THE LONG TERM PERIOD. THE UPPER TROUGHING THAT WAS APPROACHING THE AREA AT 12Z WEDNESDAY SHIFTS ACROSS DURING THE DAY. MAINTAINED 20 PERCENT CHANCES OF PRECIPITATION ACROSS WISCONSIN AS THAT SECONDARY COLD FRONT ASSOCIATED WITH THE UPPER TROUGH MOVES THROUGH. UPSTREAM...A POTENT SHORTWAVE TROUGH CURRENTLY NEAR ANCHORAGE ALASKA IS FORECAST TO DIG DOWN AND RE-ENFORCE THE TROUGH. THIS FEATURES DROPS INTO THE AREA ON THURSDAY...BRINGING WITH IT A SURGE OF ARCTIC AIR. 850MB TEMPS TUMBLE TO -22 TO -26C BY 00Z FRIDAY...AFTER BEING AT -15 TO -20C AT 00Z THURSDAY. GIVEN THE NORTHWEST FLOW AND ARCTIC ORIGIN...NO PRECIPITATION IS MENTIONED WITH THIS POTENT SHORTWAVE TROUGH. NEEDLESS TO SAY...TEMPERATURES WILL BE BELOW NORMAL WITH WIND CHILL ADVISORIES LOOKING LIKELY THURSDAY NIGHT AND EVEN FOR A FEW AREAS WEDNESDAY NIGHT. THE NORTHWEST UPPER LEVEL FLOW IS PROGGED TO STAY AROUND THROUGH FRIDAY AND SATURDAY...WITH SOME INDICATIONS OF YET ANOTHER POTENT SHORTWAVE TROUGH DROPPING THROUGH ON SATURDAY. 500MB HEIGHTS DO RISE SOME FRIDAY AND SATURDAY...SO THIS LATTER TROUGH ENDS UP A LITTLE FARTHER NORTH. DID KEEP SOME 20-30 PERCENT CHANCES AS THE TROUGH MOVES THROUGH. WITH THE INCREASING 500MB HEIGHTS...TEMPERATURES SHOULD MODERATE SOME. && .AVIATION... 1030 PM CST SAT JAN 26 2013 IMPACTFUL WEATHER SYSTEM WILL BRING A MIXED BAG OF WINTERY PCPN TO THE REGION AS WARMER AIR A LOFT...AND THEN THE POTENTIAL FOR LOSS OF ICE IN THE CLOUD AS IT PASSES...MAKE -SN/IP/FZRA/FZDZ ALL POSSIBLE. HOW FAR NORTH THE SYSTEM MOVES WILL HAVE A BIG IMPACT ON THE PTYPE FOR KRST/KLSE...WITH CURRENT THINKING MAKING -SN/IP MORE LIKELY FOR LATE MORNING/AFTERNOON SUNDAY. IP/FZRA/FZDZ START TO LOOK MORE LIKELY FOR THE EVENING HOURS AS THE WARM LOW LEVEL AIR CREEPS FARTHER NORTH. HOWEVER...MODELS DEPICT...AND SATELLITE IMAGERY SHOWS...THAT THERE IS A PRETTY STRONG DRY PUNCH IN THE MID LEVELS WITH THIS SYSTEM...AND ITS SLATED TO MOVE ACROSS THE TAF SITE SUNDAY EVENING. THIS WOULD CARVE OUT THE ICE BEARING PART OF THE CLOUD...AND THUS LEAVE FZDZ AS THE PTYPE. DIFFICULT PCPN TYPE FORECAST. VERY DIFFICULT. SOME SNOW AND ICE ACCUMULATION ARE LIKELY. EXPECT A RAPID DROP IN CIGS...WITH MID LEVEL CLOUDS AND VFR CONDITIONS INTO MID MORNING SUNDAY...DROPPING TO AROUND 1KFT OR LESS BY 18Z. VSBYS FROM 2 TO 4SM LOOK LIKELY AT THIS TIME...BUT WILL BE LOWER WHEN -SN IS THE PROMINENT PTYPE. WILL HANG ONTO SUB 2SM INTO THE EVENING...WITH BR AND FZDZ MORE OF A FACTOR. THE LIFR/IFR CIGS WILL PERSIST THROUGH SUNDAY NIGHT. MOST OF THE ACCUMULATING PCPN LOOKS TO EXIT EAST AFTER 06Z MON. && .ARX WATCHES/WARNINGS/ADVISORIES... 344 AM CST SUN JAN 27 2013 WI...WINTER STORM WARNING FROM 9 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR WIZ029-032>034-041>044-053>055-061. WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR WIZ017. MN...WINTER STORM WARNING FROM 9 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR MNZ079-086>088-094>096. IA...WINTER STORM WARNING FROM 9 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
511 AM CST SUN JAN 27 2013 .DISCUSSION... SHORT TERM (THROUGH MONDAY)... 500 AM CST FREEZING RAIN ADVISORIES HAVE BEEN POSTED FOR ALL OF THE FORECAST AREA. SHORT TERM FOCUS IS ON THE EXPECTED PERIOD OF MAINLY FREEZING RAIN...POSSIBLY MIXED WITH A BRIEF PERIOD OF SLEET AT THE ONSET OF THE PRECIPITATION. DELICATE BALANCE BETWEEN TEMPERATURES ALOFT AND AT THE SURFACE TODAY AS WELL AS HOW DRY THE LOWER LEVELS MAINTAIN LARGE DEW POINT DEPRESSIONS INTO THIS MORNING MAKE FOR A CHALLENGING FORECAST. 00Z RAOBS SHOWED THE 850 HPA TEMPERATURES ALREADY AT OR ABOVE 0C FROM MSP TO SPI TO SDF WITH +5C FROM ABR TO OMA TO SGF. VAD WINDS SHOWING THAT THE STRONG LOWER LEVEL SOUTH TO SOUTHWEST FLOW HAS SPREAD EASTWARD FROM THE SOUTHERN AND CENTRAL PLAINS TO AS FAR EAST AS WEST CENTRAL AND SOUTHWEST WI...EASTERN IA...AND WEST CENTRAL AND SOUTHWEST IL EARLY THIS MORNING. LOW LEVEL AND SURFACE FLOW REMAINS OUT OF THE SOUTHEAST ACROSS THE REGION WHICH CONTINUES TO FEED DRY AIR ACROSS THE FORECAST AREA. UPSTREAM TO THE SOUTHWEST THROUGH WEST SURFACE DEW POINTS HAVE CLIMBED INTO THE MID 30S TO LOWER 40S F AS FAR NORTH AND EAST AS THE MID MO VALLEY...THE OZARKS AND THE LOWER MS VALLEY. THIS LOW LEVEL MOISTURE WAS EVIDENT IN THE 00Z RAOBS WITH 925 HPA DEW POINT DEPRESSIONS OF ZERO TO TWO DEGREES C FROM OK SOUTH ACROSS EAST TX AND EAST TO LA. THIS MOISTURE IS PROGGED TO REACH WESTERN AND SOUTHERN IA...FAR EASTERN MO AND FAR WESTERN TN BY 12Z AND THEN SPREADS ACROSS IL FROM LATE MORNING THROUGH LATE AFTERNOON. STRONG WARM AIR ADVECTION WAS PRODUCING ISENTROPIC UPGLIDE ACROSS THE REGION BUT THE DRY LOW LEVELS WAS PREVENTING AN PRECIPITATION FROM OCCURRING ANY CLOSER THAN 250 TO 300 MI TO THE SOUTHWEST THROUGH WEST AS OF 10Z. HOWEVER A LARGE AREA OF RAIN WAS QUICKLY SPREADING INTO SO SOUTH CENTRAL IA AND NORTHEAST AND EAST CENTRAL MO AS THE MOISTURE SURGES NORTH AND NORTHEAST ALLOWING THE LOWER LEVELS TO SATURATE. SIGNIFICANT ISENTROPIC UPGLIDE THROUGH THE LOWER AND MID LEVELS AND THE CONTINUED MOISTURE ADVECTION SPREADING INTO THE LOCAL AREA IS EXPECTED TO SATURATE DOWN FROM THE MID LEVELS TO THE LOWER LEVELS ACROSS THE WESTERN COUNTIES BY MID MORNING AND THE EASTERN COUNTIES BY MIDDAY. TEMPERATURES WERE STEADY OR ROSE A DEGREE OR TWO FROM LATE LAST EVENING AND WERE MAINLY IN THE MID 20S MOST OF THE LATE NIGHT. WITH TEMPERATURES STARTING OFF NOT THAT FAR FROM FREEZING THEY ARE FORECAST TO REACH 32 OR SLIGHTLY ABOVE ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA BY EARLY AFTERNOON AND THE NORTHERN PORTION BY MID TO LATE AFTERNOON. EXPECTED ONSET OF PRECIPITATION AND TIMING OF SURFACE TEMPERATURES RISING TO FREEZING OR ABOVE WERE USED TO DETERMINE THE HOURS COVERED BY THE FREEZING RAIN ADVISORIES ACROSS THE AREA. THE STRONG SHORT WAVE OVER THE CENTRAL PLAINS EARLY THIS MORNING WILL CONTINUE FAIRLY QUICKLY NORTHEASTWARD TO THE UPPER MIDWEST BY LATE AFTERNOON AND THEN IS PROGGED TO SLOW ITS THIS EVENING AND ON PROGRESS TO FAR NORTHERN WI...THE WESTERN U.P. OF MI AND WESTERN LAKE SUPERIOR OVERNIGHT. THIS ALLOWS A CONTINUED STRONG SOUTHWEST TO WEST-SOUTHWEST LOW AND MID LEVEL FLOW TO PERSIST TONIGHT MAINTAINING THE WARM AIR ADVECTION AND THE RESULTING UVV SO RAIN WILL MOST LIKELY PERSIST WELL INTO THE NIGHT. WITH DEW POINTS IN THE MID 30S TO MID 40S ACROSS THE AREA FOG IS EXPECTED TO DEVELOP DURING THE NIGHT AND PERSIST INTO MONDAY MORNING. A CHANCE OF RAIN WILL PERSIST AS THE WARM AIR ADVECTION CONTINUES. WITH 850 HPA TEMPERATURES OF 7 TO 9C OVER THE AREA DURING MONDAY. CLOUD COVER WILL LIMIT SURFACE HEATING BUT TEMPERATES SHOULD STILL RESPOND TO THIS MID AIR MASS BY CLIMBING TO THE MID 40S NORTH AND LOWER 50S SOUTH. LONG TERM (MONDAY NIGHT THROUGH FRIDAY)... 311 AM CST MOTHER NATURE LOOKS TO HAVE SOMETHING FOR ALMOST EVERYONE DURING THIS PERIOD WITH THE POTENTIAL FOR THUNDERSTORMS (SEVERE?)...HEAVY RAIN/FLOODING...RECORD WARMTH...GUSTY WINDS...AND COLD WITH BIG ACCUMULATING SNOW ABOUT THE ONLY THING MISSING! SERIES OF WEAK IMPULSES WILL RIPPLE THROUGH THE BRISK SOUTHWESTERLY FLOW ALOFT AS DEEP TROUGH PROGRESSES EASTWARD INTO THE PLAINS. ONE SUCH WAVE AND ITS ASSOCIATED SURFACE LOW PROGGED TO AFFECT THE REGION MONDAY NIGHT WITH WARM FRONT PROGGED TO LIFT NORTH ACROSS THE AREA SENDING UNSEASONABLY WARM AND HUMID AIR FLOODING NORTHWARD INTO THE AREA. STRONG WAA/ASCENT ON THE NOSE OF THE 50KT+ LOW LEVEL JET SHOULD TRANSPORT MOISTURE/ELEVATED INSTABILITY NORTHWARD WHICH LOOKS TO BE ENOUGH TO SUPPORT ELEVATED CONVECTION MONDAY NIGHT AND HAVE INTRODUCED THUNDERSTORMS INTO THE GRIDS MONDAY NIGHT. TUESDAY LOOKS TO BE A BREEZY AND UNSEASONABLY WARM AND HUMID DAY WITH RECORD HIGHS IN JEOPARDY. WRF-NAM IS A BIT FASTER WITH THE TROUGH AND FARTHER EAST WITH THE FRONT BUT IS AN OUTLIER WITH THE GFS/UKMET/ECMWF/GEM ALL SLOWER AND SUPPORTING RECORD WARMTH OVER THE ENTIRE CWA. HAVE BUMPED UP HIGHS TUESDAY TO BE IN LINE WITH THE MAV GUIDANCE...AND CONSIDERING THE TYPICAL INABILITY OF MOS TO CAPTURE RECORD WARMTH EVEN THESE FORECAST NUMBERS COULD BE A HAIR CONSERVATIVE. ACCOMPANYING THE WARM TEMPERATURES LOOKS TO BE APRIL LEVEL HUMIDITY WITH DEW POINTS PROGGED TO CLIMB INTO THE 55-60F RANGE WHICH IF IT PANS OUT WOULD ALLOW FOR AT LEAST WEAK SURFACE BASED INSTABILITY TO DEVELOP AHEAD OF A STRONG COLD FRONT THAT MOVES THROUGH LATE TUES INTO TUES NIGHT. WILL LIKELY SEE LEFT OFF SHOWERS/STORMS MOVE OUT EARLY TUES MORNING WITH MANY DRY HOURS EXPECTED BEFORE THE NEXT UPSTREAM WAVE LEADS TO MORE WIDESPREAD SHOWERS AND THUNDERSTORMS DEVELOPING/MOVING INTO THE AREA LATER TUESDAY. UPPER FLOW IS PROGGED TO BECOME FAIRLY WELL ALIGNED WITH THE SURFACE FRONT FAVORING SLOW EASTWARD PROGRESS OF THE BLOSSOMING AREA OF RAIN/THUNDERSTORMS WITHIN THE WARM CONVEYOR BELT. NOT SURPRISINGLY GIVEN DEW POINTS NEARING 60F...PWATS ARE PROGGED TO CLIMB TO NEAR RECORD LEVELS FOR JANUARY WHICH REALLY RAISES CONCERNS ABOUT HEAVY RAINFALL AND FLOODING. UKMET/GEM/ECMWF ALL SUGGEST THAT OUR SE CWA WILL BE UNDER THE GUN FOR THIS HEAVY RAINFALL WHILE THE GFS IS MORE OF AN EAST OUTLIER FOCUSING THE HEAVY RAIN EAST OF OUR CWA. GOING TO SIDE CLOSER TO THE MODEL CONSENSUS AND BUMP UP POPS TO CATEGORICAL SE CWA AND INCLUDE MENTION OF HEAVY RAINFALL IN THE GRIDS/ZFP. FOR FURTHER DETAILS SEE HYDROLOGY SECTION BELOW. WHILE IT WOULD BE VERY RARE...CANNOT COMPLETELY RULE OUT A SEVERE THREAT IN THE AREA TUESDAY AS THE UNSEASONABLY HIGH DEW POINTS COULD RESULT IN WEAK (BUT SUFFICIENT) INSTABILITY TO SUPPORT SEVERE THUNDERSTORMS IN AN ENVIRONMENT OF VERY STRONG SHEAR AND INCREASING LARGE SCALE ASCENT. THE NEW SWODY3 OUTLOOK JUST CAME OUT AND HAS INCLUDED A SLIGHT RISK INTO OUR CWA TUESDAY AND AS BEST I CAN RECALL THIS MAY BE THE FIRST EVER DAY 3 SLIGHT RISK IN OUR CWA IN JANUARY. AS UPPER TROUGH AND ASSOCIATED SURFACE FRONT CONTINUE EASTWARD LOOK FOR BAND OF RAIN/THUNDERSTORMS TO GRADUALLY MOVE EAST OF THE AREA TUESDAY NIGHT WITH NORTHWEST WINDS USHERING IN MUCH COLDER CONDITIONS. WEDNESDAY GENERALLY LOOKS TO BE DRY BUT WITH UPPER TROUGH MOVING THROUGH THE REGION HAVE OPTED TO HANG ONTO SLIGHT CHANCE OF LIGHT SNOW/FLURRIES...BUT MORE LIKELY THAN NOT MAJORITY OF THE DAY WILL BE DRY. HAVE MAINTAINED DRY FORECAST THURS/FRIDAY BUT CERTAINLY CAN`T RULE OUT A NORTHWEST FLOW "SURPRISE" BRINGING SOME LIGHT SNOW TO THE REGION AT SOME POINT IN TIME. BEST CHANCE MIGHT BE LATER THURSDAY INTO THURSDAY NIGHT AS RE-ENFORCING SHOT OF ARCTIC AIR IS PROGGED TO ARRIVE. COULD ALSO BE SOME LIGHT SNOW HEADING INTO NEXT WEEKEND AS MILDER AIR MOVES IN AND ARCTIC AIR MASS TEMPORARILY RETREATS. 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 && .HYDROLOGY... 311 AM CST USGS ANALYSIS OF STREAMFLOW ACROSS THE CWA INDICATES THAT STREAMFLOW IS CERTAINLY BELOW AVERAGE OVER THE CWA...THOUGH LESS SO OVER THE IROQUOIS...KANKAKEE...AND VERMILLION RIVER BASINS THAN SOME OF THE BASINS FARTHER NORTH. THOSE SAME RIVER BASINS APPEAR TO BE AT RISK FOR THE HEAVIEST RAINFALL EARLY THIS WEEK WITH WIDESPREAD TOTALS OF 1-2 INCHES LOOKING LIKE A GOOD BET AND TOTALS IN EXCESS OF 2 INCHES POSSIBLE. THIS HEAVY RAIN WOULD BE FALLING ON FROZEN GROUND AND LIKELY RESULT IN MUCH LOWER THAN AVERAGE INFILTRATION RATES AND GREATER RUNOFF INCREASING THE THREAT OF FLOODING. RIVER ICE SPOTTER REPORTS FROM 1/24 INDICATE THAT THERE IS A GREAT DEAL OF ICE COVERAGE ON THE IROQUOIS AND KANKAKEE RIVERS...AND THIS IS LIKELY THE CASE ON OTHER STREAMS/RIVERS AS WELL. THE COMBINATION OF RECORD WARMTH AND RAPIDLY INCREASING STREAMFLOW COULD RESULT IN A HEIGHTENED RISK OF ICE JAM FLASH FLOODING AS ICE BECOMES DISLODGED AND SIGNIFICANT ICE FLOW BEGINS. WHILE THE MOST SIGNIFICANT THREAT OF HEAVY RAINFALL AND FLOODING APPEARS TO BE OVER THE SOUTHEAST 1/3RD OR SO OF THE CWA...AT LEAST MODERATE RAINFALL AND RECORD WARMTH COULD RESULT IN AN INCREASED RISK OF ICE JAM FLOODING OVER NORTH CENTRAL ILLINOIS AS WELL. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * FREEZING RAIN DEVELOPS TOWARD MIDDAY...POSSIBLY STARTING AS A PERIOD OF SLEET * CIGS/VSBY FALLING TO MVFR SUNDAY AFTERNOON AND EVENTUALLY IFR SUNDAY EVENING * FREEZING RAIN CHANGES TO RAIN LATE THIS AFTERNOON OR EARLY THIS EVENING AS TEMPS RISE ABOVE FREEZING * IFR/LIFR CONDITIONS LIKELY FROM MID/LATE EVENING THROUGH OVERNIGHT TONIGHT IZZI //DISCUSSION...UPDATED 09Z... HAVE NUDGED THE TIMING OF THE ARRIVAL OF THE PRECIP UP JUST A BIT BASED ON RADAR TRENDS OF LARGE SHIELD OF PRECIPITATION OVER MO MARCHING RATHER STEADILY NORTHEASTWARD. TEMPERATURES HAVE BEEN RISING QUITE QUICKLY AHEAD OF THE PRECIPITATION WITH PRECIP ALMOST ENTIRELY RAIN AT THIS TIME. DRIER AIR IN ADVANCE OF THE RAIN OVER NORTHERN ILLINOIS COULD SLOW ITS PROGRESSION A BIT BY EATING AWAY SOME OF THE LEADING EDGE AND EVAPORATIVE COOLING COULD BE ENOUGH TO COOL TEMPS SLIGHTLY. GIVEN UPSTREAM TRENDS CONFIDENCE IN FREEZING TODAY HAS WANED SOME AND THE TREND OF TEMPS RISING QUICKLY AHEAD OF THE PRECIP CONTINUES THE THREAT OF FZRA/PL MAY BE LOWER OR THE TIME WINDOW OF OCCURANCE SHORTER. PARTICULARLY CONCERNING SEEING THE LATEST RAP MODEL SHOWING TEMPS NEARING 40F AHEAD OF THE PRECIP OVER THE CHICAGO AREA...IF THIS VERIFIES THERE MAY NOT BE MUCH FROZEN/FREEZING PRECIP. NOT PLANNING ANY BIG OVERHAULS TO THE TAF FORECAST NOW BASED ON THAT ONE MODELS BUT WILL CONTINUE TO CLOSELY MONITOR TRENDS. HAVE SHORTENED THE FORECAST DURATION OF THE FZRZ IN THE TAFS WITH THIS UPDATE CYCLE. IZZI UPDATED 06Z... AN UPPER LEVEL DISTURBANCE AND WARM FRONT LIFTING NORTH ACROSS THE REGION WILL RESULT IN A PERIOD MIXED PRECIPIATION SUNDAY AFTERNOON BEFORE CHANGING TO ALL RAIN SUNDAY EVENING. FORECAST SOUNDINGS SUGGEST THAT SATURATION WILL TAKE PLACE FROM TOP-DOWN WHICH SUGGESTS THAT PRECIP COULD BRIEFLY START AS A PERIOF OF SLEET BEFORE STRONG WARM AIR ADVECTION RESULTS IN A CHANGE OVER TO FREEZING RAIN. CONFIDENCE IS LOW ON HOW QUICKLY SFC TEMPS WILL RISE ABOVE FREEZING BUT DOES APPEAR AS THOUGH AT LEAST A COUPLE HOURS...POSSIBLY LONGER...OF FZRA IS LIKELY LATER SUNDAY AFTERNOON INTO EARLY SUNDAY EVENING. STEADY RAIN EXPECTED TO END SUNDAY EVENING BUT DRIZZLE AND PERIODIC LIGHT RAIN COULD LINGER THROUGH THE NIGHT SUNDAY. INITIALLY VFR CIGS SHOULD BUILD DOWN TO MVFR AND EVENTUALLY IFR SUNDAY AFTERNOON/EVENING...WITH CORRESPONDING REDUCTION IN VSBY EXPECTED...ESPECIALLY SUNDAY EVENING AS CIGS LOWER AND SOME LIGHT FOG/DRIZZLE DEVELOPS. IZZI //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN START TIME OF PRECIP * LOW-MEDIUM CONFIDENCE IN PRECIP TYPE TODAY * HIGH CONFIDENCE IN ANY FREEZING PRECIP CHANGING TO ALL RAIN...BUT LOW CONFIDENCE IN TIMING OF CHANGE OVER * HIGH CONFIDENCE IN THE GENERAL CIG/VSBY TRENDS...BUT LOW CONFIDENCE IN PRECISE TIMING * HIGH CONFIDENCE IN WINDS IZZI //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...IFR CIGS/VIS LIKELY WITH -RA/BR. TUESDAY...SHRA/TSRA LIKELY. MVFR LIKELY/IFR POSSIBLE. WEDNESDAY THROUGH FRIDAY...MVFR CIGS PROBABLE. A FEW PERIODIC FLURRIES OR LIGHT SNOW SHOWERS POSSIBLE. KREIN && .MARINE... 216 AM CST AN ACTIVE PERIOD LIES AHEAD ACROSS THE LAKE BUT AT THIS POINT PEAK WIND SPEEDS LOOK TO PRIMARILY REMAIN BELOW GALE FORCE THOUGH THERE MAY BE A FEW PERIODS THAT COME CLOSE. HIGH PRESSURE SPREAD FROM WESTERN QUEBEC INTO THE OHIO VALLEY. LOW PRESSURE IS DEVELOPING OVER THE SOUTHERN HIGH PLAINS AND WILL TRACK NORTHEASTWARD AND CROSS NORTHERN LAKE MICHIGAN MONDAY AFTERNOON. SOUTH WINDS WILL INCREASE TODAY AS THE INFLUENCE OF HIGH PRESSURE DEPARTS AND PRESSURE START TO FALL AHEAD OF THE LOW. EXPECT SPEEDS OF AROUND 30 KT LATER THIS AFTERNOON INTO THE EVENING ESPECIALLY OVER THE SOUTHERN PART OF THE LAKE BEFORE MUCH WARMER AIR TAKES OVER ALOFT SETTING UP AN INVERSION. THIS INVERSION LOOKS TO ALLOW WINDS TO EASE OVERNIGHT AND MONDAY MORNING KEEPING THE STRONGER 40 KT SPEEDS FROM REACHING THE LAKE SURFACE. WILL CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS FOR THE NEARSHORE BUT MAY BE ABLE TO MOVE THE END TIME EARLIER FOR THE INDIANA WATERS BUT WILL HOLD OFF FOR NOW AND LET LATER SHIFTS SEE HOW THINGS MATERIALIZE. THE SURFACE LOW WILL CROSS THE NORTHERN PART OF THE LAKE MONDAY AFTERNOON ALLOWING LIGHT WINDS FOR A TIME NORTH AS THE DIRECTION SHIFTS SOUTHWESTERLY ACROSS THE SOUTH. WEAK RIDGING THEN QUICKLY CROSSES THE LAKE MONDAY EVENING KEEPING LIGHT WINDS IN PLACE BUT ANOTHER SURFACE LOW WILL BE MOVING NORTHEASTWARD FROM THE SOUTHERN PLAINS RESULTING IN A QUICK SHIFT TO INCREASING SOUTHWESTERLY WINDS. AN INVERSION WILL REMAIN IN PLACE WITH MUCH WARMER AIR OVER THE LAKE SO THE 40+ KT SPEEDS AT AROUND 1000 FT ABOVE THE SURFACE WILL REMAIN THERE WHILE LAKE LEVEL WINDS ARE HELD TO LESS THAN 30 KT CENTRAL AND SOUTH...WITH LIGHTER WINDS FAR NORTH IN THE WEAK PRESSURE GRADIENT IN THE TROUGH OF THE APPROACHING LOW. THERE IS SOME INDICATION OF THE LOW SHIFTING FURTHER NORTH WHICH WOULD THEN LEAD TO MORE OF THE LAKE SEEING THESE STRONGER WINDS. A SECOND LOW FORMS SOUTHEAST OF THE LAKE LATER TUESDAY AS A COLD FRONT CROSSES THE LAKE SHIFTING WINDS TO THE NORTHWEST. MUCH COLDER AIR WILL SPILL IN BEHIND THE FRONT BRINGING UNSTABLE AIR BACK OVER THE LAKE. AT THIS POINT WIND SPEEDS DO NOT LOOK TO INCREASE MARKEDLY DESPITE THE COLD ADVECTION BUT THERE IS STILL SOME UNCERTAINTY IN HOW THE TWO LOWS EVOLVE SO THERE IS SOME POTENTIAL FOR INCREASED WINDS OVER WHAT IS CURRENTLY FORECAST TUESDAY NIGHT AND WEDNESDAY. SEVERAL WEAKER TROUGHS WILL CROSS THE REGION FROM WEDNESDAY THROUGH EARLY NEXT WEEKEND. WINDS WILL GENERALLY REMAIN WESTERLY WITH FLUCTUATIONS FROM SOUTHWEST TO NORTHWEST AS EACH TROUGH PASSES WITH PERIODIC INCREASES IN SPEEDS. WILL NEED TO MONITOR THE STRENGTH OF THESE AS IT WOULD NOT TAKE MUCH FOR THEM TO PRODUCE AT LEAST SHORT PERIODS OF GALES BUT FOR NOW WILL KEEP PEAK SPEEDS AROUND 30 KT. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FREEZING RAIN ADVISORY...ILZ008-ILZ010-ILZ011-ILZ019-ILZ021- ILZ032-ILZ039...9 AM SUNDAY TO 4 PM SUNDAY. FREEZING RAIN ADVISORY...ILZ012-ILZ013-ILZ014-ILZ020-ILZ022- ILZ023-ILZ033...11 AM SUNDAY TO 4 PM SUNDAY. FREEZING RAIN ADVISORY...ILZ005-ILZ006...11 AM SUNDAY TO 7 PM SUNDAY. FREEZING RAIN ADVISORY...ILZ003-ILZ004...9 AM SUNDAY TO 7 PM SUNDAY. IN...FREEZING RAIN ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...11 AM SUNDAY TO 4 PM SUNDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...NOON SUNDAY TO 4 AM MONDAY. SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...NOON SUNDAY TO 10 AM MONDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
647 AM EST SUN JAN 27 2013 .AVIATION... 12Z TAFS...STRONG LOW LEVEL WARM/MOIST ADVECTION WILL OVERSPREAD NORTHERN INDIANA LATER THIS AFTERNOON. REGIONAL RADAR MOSAIC ALREADY INDICATING LEADING EDGE OF PRECIP SHIELD REACHING WEST CENTRAL IOWA INTO EASTERN MISSOURI AT 11Z. STRONGER LOW LEVEL MOISTURE TRANSPORT OVER NEXT SEVERAL HOURS SHOULD REMAIN ACROSS PORTIONS OF NORTHEAST MISSOURI INTO EASTERN IOWA/NORTHERN ILLINOIS SO SOME QUESTION EXISTS AS TO THE PROGRESSION OF THE SOUTHERN PERIPHERY OF THIS PRECIP EASTERN MISSOURI. INITIALLY VERY DRY AIR MASS ACROSS LOCAL AREA SHOULD STILL DELAY ONSET OF PRECIP TO THE 21Z-23Z TIMEFRAME...PERHAPS JUST A BIT SOONER AT KSBN. PROFILES SHOULD SUPPORT A MIX OF SLEET/FREEZING RAIN AT ONSET WITH AN EXPECTED PERIOD OF MAINLY FREEZING RAIN EARLY THIS EVENING BEFORE THE AXIS OF THE STRONG LOW LEVEL JET TO THE WEST ALLOWS PROFILES WARM ENOUGH FOR RAIN. RAPIDLY DETERIORATING CIGS TO IFR ARE ALSO EXPECTED EARLY THIS EVENING...AND TO LIFR LATE EVENING. HAVE ALSO ADDED LLWS MENTION IN ASSOCIATION WITH THIS LOW LEVEL JET AFTER 04Z. && .PREV DISCUSSION... /ISSUED 429 AM EST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH MONDAY NIGHT FORECAST CONCERN FOR THE SHORT TERM WILL BE THE POTENTIAL OF A PERIOD OF FREEZING RAIN THIS AFTERNOON INTO THIS MAINLY THIS EVENING. ELEVATED ECHOES EVIDENT ON RADAR MOSAIC THIS MORNING FROM NORTH CENTRAL WISCONSIN INTO SOUTHERN LOWER MICHIGAN ASSOCIATED WITH LEADING EDGE OF STRONGER 850-700 HPA THETA ADV. THIS ELEVATED FORCING THIS MORNING WILL ONLY SERVE IN TOP DOWN SATURATION WITH DEEPER MOISTURE AND STRONGER LOW LEVEL THEATE ADVECTION SITUATED BACK ACROSS THE SOUTHERN/CENTRAL PLAINS WHERE RAIN HAS BEEN EXPANDING IN COVERAGE. 06Z RAP LOW LEVEL MOISTURE TRANSPORT PROGS DEPICTING STRONGEST 925 HPA TRANSPORT VECTORS INTO MISSOURI/SOUTHERN IOWA THIS AFTERNOON WITH ADVECTION SOMEWHAT DELAYED ACROSS LOCAL AREA DUE TO WEAK LOW LEVEL SOUTHEAST WIND COMPONENT ASSOCIATED WITH DEPARTING LOW LEVEL ANTICYCLONE. IT STILL APPEARS CHANCES OF PRECIP WILL INCREASE ACROSS WESTERN PORTIONS OF THE FORECAST AREA TOWARD THE 21Z TIMEFRAME BUT PRECIPITATION SHOULD BE INITIALLY VERY LIGHT. CANNOT COMPLETELY DISCOUNT A VERY BRIEF PERIOD OF A SNOW/SLEET MIX DUE TO WET BULB EFFECTS...BUT STRENGTH OF LOW LEVEL WARM/MOIST ADVECTION VIA AN APPROACHING 60 KNOT LOW LEVEL JET AXIS SHOULD SUPPORT PRECIP TYPE OF MAINLY SLEET/FREEZING RAIN MIX BY THE TIME MORE APPRECIABLE PRECIP RATES WOULD BE OBSERVED LATE THIS AFTERNOON AS LOW LEVELS SATURATE. STRENGTH OF LOW LEVEL MOISTURE ADVECTION AND INSPECTION OF RAP/NAM FORECAST SOUNDINGS EVEN OFFERS SOME QUESTION AS TO THE POSSIBILITY THAT ONCE LOW LEVEL SATURATION OCCURS...PRECIPITATION TYPE MAY BE MAINLY IN THE FORM OF RAIN ACROSS THE FAR SOUTH/SOUTHWEST. HAVE CONTINUED TO RELY MORE ON NAM IDEA IN TERMS OF INITIAL LOW LEVEL SATURATION/WET BULB PROCESSES WITH GFS OFTEN EXHIBITING A MOIST BIAS IN RAPID LOW LEVEL MOISTENING WITH THIS TYPE OF SETUP. IT STILL APPEARS AS THOUGH MOST LOCATIONS MAY RECEIVE A 2 TO 4 HOUR PERIOD OF MIXED PRECIP AND FREEZING RAIN THREAT BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING STILL APPEARS TO BE ACROSS THE FAR NORTHEAST WHICH IS ALSO SUPPORTED BY SREF PROBABILISTIC PRODUCTS. GIVEN INCREASING CONFIDENCE THAT PRIMARY IMPACTS WOULD BE FROM A PERIOD OF FREEZING RAIN WITH LITTLE IF ANY SLEET ACCUMULATION...WILL REPLACE THE WINTER WEATHER ADVISORY WITH A FREEZING RAIN ADVISORY. LATEST DATA CONTINUES TO SUGGEST THAT DURATION OF FREEZING PRECIP MAY BE SLIGHTLY SHORTER THAN PREVIOUSLY ANTICIPATED...ESPECIALLY ACROSS SOUTHERN HALF OF THE AREA BUT WILL KEEP TIMING OF WSW THE SAME FOR BOTH SEGMENTS AND OPT TO HOLD ONTO SOUTHERN PORTIONS OF THE ADVISORY AT THIS TIME. EVEN AFTER TEMPERATURES WARM ABOVE FREEZING THIS EVENING...RECENT VERY COLD TEMPS AND COLD GROUND CONDITIONS MAY STILL SUPPORT SOME FREEZING ON ROADWAYS FOR A TIME AFTER TEMPS RISE ABOVE FREEZING...ESPECIALLY ACROSS NORTHERN HALF. HAVE MAINTAINED ICE ACCUMULATIONS IN THE 0.05 TO 0.1 INCH RANGE...WITH THE HIGHER END OF THIS RANGE EXPECTED ACROSS FAR NORTH/NORTHEAST. BROAD ISENTROPIC UPGLIDE TO CONTINUE INTO MONDAY WITH ANOTHER LOW AMPLITUDE MID LEVEL WAVE TRACKING ACROSS THE GREAT LAKES REGION. NOT MUCH ORGANIZATION EXPECTED TO PRECIP ON MONDAY BUT WITH BROAD ISENTROPIC UPGLIDE AND WEAK MID LEVEL FORCING WILL CONTINUE TO CARRY HIGH RAIN POPS THROUGH MONDAY/MONDAY NIGHT. NEXT WARM FRONTAL SURGE ASSOCIATED WITH AMPLIFYING UPSTREAM LONGWAVE TROUGH SHOULD RESULT IN INCREASED PRECIP CHANCES MONDAY NIGHT WITH EVEN THE POSSIBILITY OF SOME EMBEDDED THUNDER ACROSS THE WEST LATE IN THE NIGHT. TEMPS SHOULD EXHIBIT NON DIURNAL TENDENCIES MONDAY NIGHT WITH THE WARM FRONT...POSSIBLY EVEN RISING INTO THE LOWER 50S ACROSS THE SOUTH BY MORNING. LONG TERM...TUESDAY THROUGH SATURDAY PROGRESSIVE HIGH AMPLITUDE TROUGH WILL BE FIRMLY IN PLACE ACROSS THE ROCKIES AT THE START OF THE PERIOD TUESDAY WITH A REMARKABLE 150+ KNOT MERIDIONAL UPPER LEVEL JET ON THE DOWNSTREAM SIDE. THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE IS IMPRESSIVE AND SEVERAL WAVES OF LOW PRESSURE ARE EXPECTED TO DEVELOP ALONG IT AS THE TROUGH INCHES ACROSS OUR REGION. BUT FIRST...OUR CWA WILL BE FIRMLY IN SOUTHWEST FLOW ON TUESDAY WITH CONTINUED WARM/MOIST AIR ADVECTION. 850MB DEWPOINTS CLIMB TO AROUND 10C WITH PW VALUES WELL OVER AN INCH BY LATE TUESDAY. SURFACE DEWPOINTS ALSO STILL EXPECTED TO CLIMB INTO THE MID 50S...MAKING FOR A VERY WARM DAY BY JANUARY STANDARDS. IN FACT...LATEST GUIDANCE IS SHOWING HIGHS NEAR OR ABOVE THE RECORDS (58 FOR SBN AND 62 FOR FWA...BOTH SET IN 1914). BUMPED UP HIGHS BUT WILL LEAVE THEM JUST BELOW 60F FOR MOST AREAS GIVEN CONCERNS OVER STILL VERY COLD GROUND TEMPERATURES. PRECIP CHANCES/AMOUNTS DURING THE DAY TUESDAY WILL DEPEND ON TIMING AND EVOLUTION OF LOW LEVEL JET WITH RAGGED ISENTROPIC ASCENT SUPPORTING MAINLY JUST SCATTERED SHOWERS UNTIL THE FRONT ARRIVES. MUCH BETTER FORCING WILL ARRIVE LATE TUESDAY WITH STRONG MIDLEVEL HEIGHT FALLS AND VERY FAVORABLE UPPER LEVEL JET DYNAMICS. THIS WILL FAVOR SURFACE CYCLOGENESIS SOMEWHERE OVER THE GREAT LAKES REGION WITH COPIOUS AMOUNTS OF RAINFALL ALONG THE TRAILING COLD FRONT. LATEST NAM BUFR SOUNDINGS ARE ALSO MUCH MORE OMINOUS REGARDING THUNDER POTENTIAL WITH ALMOST 1000 J/KG OF ELEVATED CAPE. THIS IS PROBABLY OVERDONE BUT GIVEN THE STRENGTH OF THE DEVELOPING LLJ COULD EASILY SEE SOME THUNDER OCCURRING LATE TUESDAY AND WILL ADD MENTION TO THE FORECAST. GIVEN THE POTENTIAL FOR CONVECTION COUPLED WITH STRONG WARM/MOIST AIR ADVECTION AHEAD OF THE FRONT AND EXCELLENT FORCING ALOFT...QPF AMOUNTS IN EXCESS OF AN INCH ARE POSSIBLE TUESDAY NIGHT. THIS CERTAINLY RAISES THE CONCERN FOR FLOODING WITH MELTING SNOWPACK IN THE NORTH AND LIKELY STILL FROZEN GROUND. ARCTIC AIR RETURNS BY LATE WEDNESDAY WITH THE REESTABLISHMENT OF NORTHWEST FLOW AND CAA. COLDEST AIR WILL TAKE SOME TIME TO FILTER INTO THE REGION SO THERE MAY BE A BRIEF LULL IN THE PRECIP BEFORE THE LAKE EFFECT GETS GOING BUT WILL MAINTAIN HIGH CHANCE POPS ON WEDNESDAY GIVEN UNCERTAINTY IN EXACT TIMING OF EXITING FRONT. WILL ALSO LIKELY BE AN ATYPICAL DIURNAL CURVE WITH AFTERNOON TEMPS FALLING FROM MORNING HIGHS AROUND 40F. LAKE RESPONSE DOESNT TRULY LIGHT UP UNTIL THURSDAY WITH THE APPROACH OF A VIGOROUS SHORTWAVE AND 850MB TEMPS BOTTOMING OUT IN THE LOW -20S. LAKE EFFECT SNOW WILL CONTINUE THROUGH FRIDAY BUT A WNW FETCH WILL LIKELY CONFINE BIGGEST IMPACTS TO OUR EXTREME NORTHERN COUNTIES. HIGH TEMPS DURING THIS PERIOD WILL LIKELY STRUGGLE TO GET ABOVE 20F GIVEN AFOREMENTIONED 850MB TEMPS. LOW LEVEL RIDGE AXIS SHIFTS EAST ON FRIDAY BUT ONLY A BRIEF RESPITE FROM PRECIP CHANCES BEFORE ANOTHER CLIPPER SYSTEM DIVES ACROSS THE REGION ON SATURDAY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR INZ006-007-009. FREEZING RAIN ADVISORY FROM 3 PM EST /2 PM CST/ THIS AFTERNOON TO MIDNIGHT EST /11 PM CST/ TONIGHT FOR INZ003>005-008- 012>018-020-022>027-032>034. MI...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR MIZ078>081. FREEZING RAIN ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EST TONIGHT FOR MIZ077. OH...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR OHZ001-002-004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...MARSILI LONG TERM...AGD AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
535 AM CST SUN JAN 27 2013 .UPDATE... RADAR TRENDS INDICATE SLEET/FREEZING RAIN HAS MOVED INTO OR WILL DEVELOP VERY SOON IN THE FAR SOUTHWEST PARTS OF THE CWFA. RECENT RAP TRENDS CONTINUE TO SHOW A VERY RAPID TOP DOWN SATURATION OCCURRING THIS MORNING WITH WBZ TEMPERATURES AT THE SFC REMAINING BELOW FREEZING. TEMPERATURES WILL BE THE KEY AND THE DRY ATMOSPHERE SHOULD INITIALLY ALLOW TEMPERATURES TO DROP ONCE THE PRECIPITATION BEGINS. MAX TEMPERATURES TODAY LOOK TO OCCUR CLOSE TO 6 PM. ..08.. && .AVIATION... VFR CONDITIONS WILL COLLAPSE TO IFR/LIFR WITH FZRA/PL AS A STORM SYSTEM MOVES ACROSS THE AREA. SIGNIFICANT ICE ACCUMULATIONS ARE EXPECTED AT KDBQ AND ARE POSSIBLE AT KCID/KMLI. WARM AIR MOVING UP FROM THE SOUTH WILL ALLOW THE FZRA/PL TO CHANGE OVER TO RA AT KBRL/KMLI BEFORE SUNSET AND AFTER SUNSET AT KCID/KDBQ. THE WARM AIR OVER COLD GROUND WILL RESULT IN FG WITH LIFR CONDITIONS AFT 03Z/28. ..08.. && .PREV DISCUSSION... /ISSUED 400 AM CST SUN JAN 27 2013/ SYNOPSIS... 6Z SFC ANALYSIS HAS LOWS IN SOUTHEAST WYOMING AND EASTERN COLORADO WITH ASSOCIATED FRONTS CONNECTING THEM. A WEAK LOW WAS NEAR K9V9 IN SOUTH DAKOTA WITH A WARM FRONT RUNNING ROUGHLY ALONG THE MISSOURI RIVER INTO CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE GREAT LAKES WITH 20S AND HIGHER IN THE PLAINS AND LOWER MISSISSIPPI VALLEY. SHORT TERM...EARLY THIS MORNING AND TODAY... HEADLINES...HAVE TRANSITIONED TO A FREEZING RAIN ADVISORY FOR MOST OF THE AREA. AN ICE STORM WARNING HAS BEEN ISSUED FOR THE HWY 20 CORRIDOR FROM DBQ ON WEST. THERE SHOULD BE A QUICK ICE ACCUMULATION WITHIN THE FIRST COUPLE HOURS ONCE THE FREEZING RAIN BEGINS AT ANY ONE LOCATION. BASED ON CURRENT RADAR AND RAP TRENDS...FREEZING RAIN WILL BEGIN MOVING INTO THE FAR SOUTHWEST/WEST PARTS OF THE CWFA IN THE 10-12Z TIME FRAME. FCST SOUNDINGS SHOW CONSIDERABLE DRY AIR ACROSS THE AREA AND WBZ TEMPERATURES AT THE SFC AND 0.5 KM ARE BELOW FREEZING INITIALLY. THUS TREMENDOUS EVAPORATIVE COOLING WILL OCCUR TO HELP HOLD TEMPERATURES DOWN AND ALLOW SLEET TO MIX IN WITH THE FREEZING RAIN. BASED ON RAP TRENDS...TOP DOWN SATURATION WILL RAPIDLY OCCUR OVER ALL BUT THE FAR EASTERN PARTS OF THE CWFA BY MID MORNING. WBZ TEMPERATURES CONTINUE TO REMAIN BELOW FREEZING AT THE SFC AND AT 0.5 KM BUT WBZ TEMPERATURES SLOWLY RISE FROM SOUTHWEST TO NORTHEAST DURING THE MORNING. THUS FREEZING RAIN WITH SOME SLEET WILL BE SEEN ACROSS THE ENTIRE AREA DURING THE MORNING. TREMENDOUS WAA CONTINUES INTO THE AFTERNOON HOURS WHICH WILL ALLOW THE FREEZING RAIN/SLEET TO CHANGE OVER TO ALL RAIN FROM SOUTHWEST TO NORTHEAST. HOWEVER...MOST AREAS ALONG/NORTH OF HWY 30 WILL LIKELY SEE FREEZING RAIN/SLEET CONTINUE THROUGH THE AFTERNOON HOURS. DUE TO THE TREMENDOUS EVAPORATIVE COOLING THAT WILL OCCUR DURING THE DAY...TEMPERATURES MAY INITIALLY DROP SEVERAL DEGREES ONCE THE PRECIPITATION BEGINS. HOWEVER...THE SURGE OF MOISTURE MOVING NORTH INTO THE AREA WILL BODILY FORCE TEMPERATURES UP AGAIN AS THE DAY PROGRESSES. ..08.. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY... SUNDAY NIGHT THROUGH TUESDAY WILL BE A VERY ACTIVE PERIOD WITH CHALLENGING WEATHER THROUGHOUT. SUNDAY EVENING THE DAYTIME STORM SYSTEM GRADUALLY SHIFTS NORTHEAST. THE UPPER LEVEL SHORTWAVE SWEEPS NORTHEAST OF THE AREA...BUT THE STRONG WARM AIR ADVECTION AND MOISTURE ADVECTION CONTINUES AS A WEAK SURFACE LOW RIPPLES UP FROM KANSAS TO WISCONSIN OVERNIGHT. THE STRONG WARM AIR ADVECTION WILL CAUSE SURFACE TEMPERATURES TO CONTINUE TO WARM OVERNIGHT. WHILE TEMPERATURES ACROSS THE HIGHWAY 20 CORRIDOR WILL BE JUST BELOW FREEZING AS OF 00Z...THEY SHOULD RISE ABOVE FREEZING AROUND MID EVENING. THIS SHOULD END THE FREEZING RAIN THREAT FOR THE ENTIRE AREA BY 03Z TONIGHT. THUS...THE ENDING TIME OF THE NORTHERN MOST PORTIONS OF THE FREEZING RAIN ADVISORY AND ICE STORM WARNING. AFTERWARDS...A WEAK TROUGH MOVES ACROSS THE AREA OVERNIGHT. TEMPERATURES SHOULD REMAIN RELATIVELY WARM OVERNIGHT...ABOVE FREEZING. SO...WHILE I EXPECT SOME LINGERING LIGHT PRECIPITATION OVERNIGHT IN THE VICINITY OF THIS TROUGH AXIS...FREEZING RAIN SHOULD NOT BE A CONCERN. MONDAY AND TUESDAY THIS WEAK SURFACE TROUGH AXIS SAGS TO ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. AT UPPER LEVELS A LARGE SCALE TROUGH MOVES ACROSS THE ROCKIES MONDAY...AND OVER THE MIDWEST ON TUESDAY. THIS UPPER LEVEL TROUGH AND THE SOUTHWEST FLOW OVER THE MIDWEST AHEAD OF IT...IS EXPECTED TO GENERATE A NEW SURFACE LOW OVER EASTERN COLORADO...AND SWEEP NORTHEAST ACROSS IOWA OR WESTERN ILLINOIS ON TUESDAY. THE GFS IS THE FARTHEST WEST OF THE MODELS...AND RUNS THE SURFACE LOW OVER CENTRAL IOWA...WHILE THE NAM AND ECMWF ARE FARTHER EAST AND ARE CLOSER TO THE MISSISSIPPI RIVER. THIS IS GOING TO BRING ANOTHER SURGE OF WARM AIR INTO THE AREA MONDAY NIGHT AND TUESDAY...WITH HIGHS EXPECTED IN THE 40S AND 50S ON MONDAY AND TUESDAY...WITH VERY LARGE GRADIENTS ACROSS THE CWFA. WITH THE SURFACE LOW PASSAGE THERE SHOULD BE A SURGE OF RAINFALL...LIKELY WITH CONVECTIVE ELEMENTS EMBEDDED WITHIN IT. HAVE INCLUDED SOME ISOLATED THUNDER FOR PORTIONS OF THE AREA AS MID LEVEL LAPSE RATES AND THE DYNAMICS MAY BE ABLE TO SUPPORT SOME RUMBLES OF THUNDER. BEHIND THIS SURFACE LOW WE FINALLY GET THE COLD FRONT TO SWEEP THROUGH THE AREA...BRINGING MUCH COLDER AIR TO THE AREA TUESDAY NIGHT. WHILE I DO NOT EXPECT MUCH PRECIPITATION BEHIND THE COLD FRONT...WHAT IS THERE SHOULD GRADUALLY CHANGE OVER TO ALL SNOW OVERNIGHT. BY WEDNESDAY MORNING WE WILL BE BACK INTO THE COLD AIR AGAIN...WITH HIGHS ON WEDNESDAY IN THE 20S TO LOW 30S. STRONG COLD AIR ADVECTION THROUGH THE DAY WITH NORTHWEST FLOW BEHIND THE UPPER LEVEL TROUGH TO BRING A FRESH SURGE OF COLD AIR. THE 500MB COLD POOL IS PRETTY STEEP...SO WE MAY HAVE SOME INSTABILITY SHOWERS DURING THE DAY...BUT JUST ENOUGH UNCERTAINTY SO HAVE LEFT OUT FOR NOW. THURSDAY THROUGH SATURDAY THE MODELS KEEP US IN STRONG NORTHWEST FLOW WITH SOME HINTS AT A FAST MOVING SHORTWAVE TO DROP THROUGH AT SOME POINT. MODELS ARE QUITE DIFFERENT AT THIS TIME...AS CAN BE EXPECTED WITH SUCH A SMALL SCALE FEATURE. FOR NOW AM CARRYING SOME SLIGHT CHANCES FOR FRIDAY NIGHT AND SATURDAY...THOUGH WE MAY ALSO NEED SOME ON THURSDAY NIGHT AS WELL. TEMPERATURES WILL BE BACK TO COLDER THAN NORMAL VALUES FOR THIS TIME OF YEAR...WITH A WARM-UP EXPECTED ON SATURDAY TO NEAR NORMAL. LE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR JACKSON. FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR DES MOINES-HENRY IA-JEFFERSON-KEOKUK-LEE-VAN BUREN-WASHINGTON. FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR BENTON- CEDAR-CLINTON-IOWA-JOHNSON-JONES-LINN-LOUISA-MUSCATINE- SCOTT. ICE STORM WARNING UNTIL 9 PM CST THIS EVENING FOR BUCHANAN- DELAWARE-DUBUQUE. IL...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR CARROLL- JO DAVIESS-STEPHENSON. FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR HANCOCK- HENDERSON-MCDONOUGH-WARREN. FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR BUREAU- HENRY IL-MERCER-PUTNAM-ROCK ISLAND-WHITESIDE. MO...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR CLARK- SCOTLAND. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
848 AM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 844 AM MST SUN JAN 27 2013 CANCELLED ADVISORY FOR SHERMAN AND YUMA COUNTIES AND EXTENDED REMAINING ADVISORY THROUGH 18Z. BASED ON CURRENT TRENDS AND SHORT RANGE GUIDANCE I EXPECT DENSE FOG TO LINGER LONGER ACROSS MY NORTHEAST CWA. HRRR WHICH HAS BEST HAND ON CURRENT CONDITIONS SHOWS FOG DISSIPATING AROUND 18Z IN THE FAR NORTHEAST. THE WEST/SOUTHWEST EDGE OF FOG/STRATUS IS QUICKLY ERODING AND CONDITIONS HAVE IMPROVED. FURTHER IMPROVEMENT WILL BE EXPECTED FROM THE WEST TO THE EAST THROUGH THE REST OF THE MORNING. UPDATE ISSUED AT 702 AM MST SUN JAN 27 2013 HILL CITY AND WRAY HAVE BOTH REPORTED VISIBILITIES OF 1/4 MILE OR LESS SO HAVE ADDED THEM TO THE ADVISORY. UPDATE ISSUED AT 514 AM MST SUN JAN 27 2013 JUST ISSUED A DENSE FOG ADVISORY. AREAS OF DENSE FOG HAVE BECOME MORE WIDESPREAD OVER MOST OF EXTREME SOUTHWEST NEBRASKA AND THE FAR NORTH AND NORTHWEST PORTIONS OF NORTHWEST KANSAS. THESE CONDITIONS HAVE PERSISTED AND GOT WORSE. EVEN DESPITE OF DOWNSLOPE WINDS...ALBEIT LIGHT...THE DENSE FOG HAS CONTINUE. SMALL SCALE MODEL OUTPUT HAVING A DIFFICULT TIME GETTING A HANDLE ON THIS. RUC STARTED OUT WELL BUT IS NOW FADING. HRRR HAS BECOME MUCH BETTER IN DEPICTING THIS. SO IN ADDITION THE LOCATIONS ALREADY EXPERIENCING DENSE FOG...ALSO PUT THE ADVISORY INTO RED WILLOW AND NORTON COUNTIES PER OBSERVATIONAL TRENDS AND BEST MODEL OUTPUT. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 419 AM MST SUN JAN 27 2013 NUMEROUS FORECAST PROBLEMS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. FLOW IS SPLITTING OVER THE WESTERN PORTION OF THE COUNTRY. AN UNORGANIZED TROUGH WITH SMALLER WAVES WITHIN IT IS MOVING THROUGH THE AREA AT THIS TIME. THIS SYSTEM BROUGHT LIGHT RAIN TO THE AREA. THIS RAINFALL HAS MOVED NORTH OF THE AREA. MODELS INITIALIZED FINE ON THE JET. UPPER AIR ANALYSIS AND ESPECIALLY SATELLITE SHOWS THAT THE GFS AND ECMWF ARE HANDLING THE MID LEVELS THE BEST...ESPECIALLY IN OUR AREA. NAM DID NOT HAVE ANY PRECIPITATION OVER THE AREA TONIGHT. MODELS ARE HAVING A HARD TIME PLACING THE FOG AND STRATUS RIGHT NOW. MODELS WERE ALSO HAVING TROUBLE AT THE SURFACE. THE RUC AND ECMWF WERE DOING THE BEST. MODELS WERE CLOSE ON THE LOW LEVEL THERMAL FIELD WITH THE ECMWF AND UKMET DOING A LITTLE BETTER THAN THE GFS AND CANADIAN TODAY/TONIGHT...INITIAL PROBLEM WILL BE CLOUDS AND FOG. MODELS DOING A POOR JOB IN DEPICTING THIS REALITY AT THIS TIME. THE RUC AND TO A LESSER EXTENT THE HRRR IS GETTING THIS. PLAN ON WATCHING TRENDS AS LONG AS POSSIBLE BEFORE ADJUSTING THE BEST OUTPUT WITH THAT. MODELS HANG CLOUDS AROUND A WHILE. VERY DRY AIR PER SATELLITE AND ANALYSIS SHOULD QUICKLY WORK ITS WAY INTO THE AREA BY 18Z. SO EXPECT MOST OF THE CLOUD COVER AT ALL LEVELS TO BE GONE. LATEST GUIDANCE HAS BACKED OFF ON THE WINDS AND WILL ADJUST ACCORDINGLY. COMBINATION OF DOWNSLOPE WINDS AND LITTLE CLOUD COVER SHOULD ALLOW FOR A GOOD WARM UP. ANALYSIS SHOWS THAT AIR MASS WILL BE NEARLY THE SAME AS YESTERDAY. ALTHOUGH THE 06Z NAM BACKED OFF ITS EARLIER WARMER TEMPERATURES BUT IS STILL VERY MILD. HAVE KEPT THE MAXES THE NEARLY THE SAME BUT POTENTIAL THERE THAT MAXES COULD BE WARMER. LIGHT WINDS ON THE BACK SIDE OF THE SURFACE RIDGE DEVELOP OVER THE EASTERN HALF OR SO. BOUNDARY LAYER RH INCREASES IN THIS SAME AREA. AIR MASS LOOKS TO CHANGE LITTLE SO THAT MAKES SENSE. PREVIOUS FORECAST HAD FOG IN THERE AND LEFT THE FOG FORECAST ALONE. LIGHTER WINDS EAST WILL MAKE FOR COOLER MINS WITH WARMER MINS FURTHER WEST WITH DOWNSLOPING AND SOME WARM AIR ADVECTION. MONDAY/MONDAY NIGHT...LEFT THE MORNING FOG IN THERE. MAY HAVE SOME LOW LEVEL CLOUD COVER IN THERE WITH SOME INCREASE IN MID AND HIGH LEVEL CLOUD COVER. MODELS HAVE MAJOR DIFFERENCES IN THE AMOUNT OF WARMUP FOR THIS DAY. 06Z NAM HAS SLOWED ITS ARRIVAL OF THE COLD FRONT AND IS NOW NEAR TO SLIGHTLY SLOWER THAN THE ECMWF WHICH LOOKS BETTER IN HANDLING THIS. IN FACT THE ECMWF LOOKS THE FASTEST WITH REMAINING NEAR TO MUCH SLOWER THAN IT. AS A RESULT THE FRONT LOOKS TO ONLY MAKE IT INTO THE NORTHERN PORTION BY LATE IN THE DAY. IF THE CLOUDS DO NOT MESS UP THE TEMPERATURES...IT COULD END UP BEING VERY WARM ESPECIALLY IN THE SOUTHEAST HALF WHICH SHOULD GET THE WHOLE DAY OF HEATING. CONSIDERING THE TREND ON THE FRONTAL ARRIVAL AND THE INCREASE IN THE TEMPERATURE GUIDANCE...WARMED UP THE MAXES... ESPECIALLY IN THE SOUTHEAST WHICH COULD GET CLOSE TO 70. IF THIS SCENARIO PANS OUT...THE FAR WESTERN PORTION OF THE FORECAST AREA GETS CLOSE TO 20 PERCENT RELATIVE HUMIDITY AND GUSTS NEAR 25 MPH. THE DAY SHIFT WILL HAVE TO TAKE ANOTHER LOOK AT THIS. FRONT BLASTS THROUGH DURING THE NIGHT. GRADIENT AND RATHER HIGH 3 HOUR PRESSURE RISES WOULD INDICATE WINDY CONDITIONS DURING THE EVENING BEHIND THE FRONT. A RATHER STRONG SOUTHWEST TO NORTHEAST JET BEGINS TO MOVE ACROSS THE AREA DURING THE DAY AND EVENING. THIS PUTS THE SOUTHEAST HALF OF THE AREA IN THE RIGHT REAR QUADRANT DURING THE AFTERNOON AND INTO THE EVENING HOURS. EVEN THOUGH MAY BE HERE IN THE AFTERNOON...THE MOISTURE PROFILE DOES NOT SUPPORT ANY PRECIPITATION BEFORE 00Z. LIFT AND MOISTURE DO COME IN AFTER 00Z. HOWEVER THEY DO NOT SYNC UP WELL. THE LIFT AND EVEN SOME INSTABILITY ARE FURTHER TO THE EAST THAN THE DEEPEST MOISTURE. LIFT AND MOISTURE PROFILES MATCH UP WELL WITH THE DETERMINISTIC AND HPC QPF. THIS IS ALSO SUPPORTED BY THE GEFS/SREF PRECIPITATION PROBABILITIES. ALL THIS MEANS THAT THE NORTHWEST HALF WILL SEE THE BEST CHANCE OF PRECIPITATION. WITH ALL THE NEW DATA SUPPORTING THE CURRENT FORECAST VERY WELL...DID NOT MAKE ANY CHANGES TO IT. TUESDAY/TUESDAY NIGHT...AGAIN NEW GUIDANCE IS VERY SUPPORTIVE OF THE CHANCE OF PRECIPITATION/PRECIPITATION TYPE FORECAST THROUGH THE MORNING. SO LEFT THOSE GRIDS THROUGH 18Z ALONE. MOST OF THE LIFT AND MOISTURE IS GONE BY 18Z. LINGERING FLURRIES OR SPRINKLES IN THE AFTERNOON WILL BE MORE LIKELY THAN MEASURABLE SO MADE THAT CHANGE. COLD FRONT WILL BE SOUTH OF THE AREA BY THE BEGINNING OF THE DAY. DEFINITELY WILL BE COOLER WITH THE MODELS SURPRISINGLY IN GOOD AGREEMENT. PROBLEM IS THAT THE AGREEMENT IS WARMER THAN CURRENT FORECAST. WITH THE POSSIBILITY OF A DECENT AMOUNT OF SUN AND SOME DOWNSLOPE WINDS CAN DEFINITELY SEE THE WARMER TEMPERATURES. SO RAISED THE MAXES A LITTLE. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 419 AM MST SUN JAN 27 2013 MODEL GUIDANCE HAVING A HARD TIME CATCHING ONTO THE STRATUS AND FOG CURRENTLY AFFECTING BOTH TAF SITES. THE RUC BY FAR IS THE BEST MODEL. AT THIS TIME EXPECT IFR TO LIFR CONDITIONS THROUGH MID MORNING WITH KGLD HAVING THE WORST CONDITIONS. AFTER THAT CONDITIONS SHOULD IMPROVE TO MVFR BY LATE MORNING WITH VFR CONDITIONS PREVAILING NEAR OR SHORTLY AFTER 18Z OR 19Z. IN THE LATER PORTION OF THE PERIOD AT KMCK...FOG IS EXPECTED TO DEVELOP ONCE AGAIN. AT THIS TIME IT LOOKS LIKE THE FOG REMAINS EAST OF KGLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR KSZ001>004-014>016. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...DR SHORT TERM...BULLER LONG TERM...JTL AVIATION...DDT
AREA FORECAST DISCUSSION
NWS GOODLAND KS
703 AM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 702 AM MST SUN JAN 27 2013 HILL CITY AND WRAY HAVE BOTH REPORTED VISIBILITIES OF 1/4 MILE OR LESS SO HAVE ADDED THEM TO THE ADVISORY. UPDATE ISSUED AT 514 AM MST SUN JAN 27 2013 JUST ISSUED A DENSE FOG ADVISORY. AREAS OF DENSE FOG HAVE BECOME MORE WIDESPREAD OVER MOST OF EXTREME SOUTHWEST NEBRASKA AND THE FAR NORTH AND NORTHWEST PORTIONS OF NORTHWEST KANSAS. THESE CONDITIONS HAVE PERSISTED AND GOT WORSE. EVEN DESPITE OF DOWNSLOPE WINDS...ALBEIT LIGHT...THE DENSE FOG HAS CONTINUE. SMALL SCALE MODEL OUTPUT HAVING A DIFFICULT TIME GETTING A HANDLE ON THIS. RUC STARTED OUT WELL BUT IS NOW FADING. HRRR HAS BECOME MUCH BETTER IN DEPICTING THIS. SO IN ADDITION THE LOCATIONS ALREADY EXPERIENCING DENSE FOG...ALSO PUT THE ADVISORY INTO RED WILLOW AND NORTON COUNTIES PER OBSERVATIONAL TRENDS AND BEST MODEL OUTPUT. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 419 AM MST SUN JAN 27 2013 NUMEROUS FORECAST PROBLEMS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. FLOW IS SPLITTING OVER THE WESTERN PORTION OF THE COUNTRY. AN UNORGANIZED TROUGH WITH SMALLER WAVES WITHIN IT IS MOVING THROUGH THE AREA AT THIS TIME. THIS SYSTEM BROUGHT LIGHT RAIN TO THE AREA. THIS RAINFALL HAS MOVED NORTH OF THE AREA. MODELS INITIALIZED FINE ON THE JET. UPPER AIR ANALYSIS AND ESPECIALLY SATELLITE SHOWS THAT THE GFS AND ECMWF ARE HANDLING THE MID LEVELS THE BEST...ESPECIALLY IN OUR AREA. NAM DID NOT HAVE ANY PRECIPITATION OVER THE AREA TONIGHT. MODELS ARE HAVING A HARD TIME PLACING THE FOG AND STRATUS RIGHT NOW. MODELS WERE ALSO HAVING TROUBLE AT THE SURFACE. THE RUC AND ECMWF WERE DOING THE BEST. MODELS WERE CLOSE ON THE LOW LEVEL THERMAL FIELD WITH THE ECMWF AND UKMET DOING A LITTLE BETTER THAN THE GFS AND CANADIAN TODAY/TONIGHT...INITIAL PROBLEM WILL BE CLOUDS AND FOG. MODELS DOING A POOR JOB IN DEPICTING THIS REALITY AT THIS TIME. THE RUC AND TO A LESSER EXTENT THE HRRR IS GETTING THIS. PLAN ON WATCHING TRENDS AS LONG AS POSSIBLE BEFORE ADJUSTING THE BEST OUTPUT WITH THAT. MODELS HANG CLOUDS AROUND A WHILE. VERY DRY AIR PER SATELLITE AND ANALYSIS SHOULD QUICKLY WORK ITS WAY INTO THE AREA BY 18Z. SO EXPECT MOST OF THE CLOUD COVER AT ALL LEVELS TO BE GONE. LATEST GUIDANCE HAS BACKED OFF ON THE WINDS AND WILL ADJUST ACCORDINGLY. COMBINATION OF DOWNSLOPE WINDS AND LITTLE CLOUD COVER SHOULD ALLOW FOR A GOOD WARM UP. ANALYSIS SHOWS THAT AIR MASS WILL BE NEARLY THE SAME AS YESTERDAY. ALTHOUGH THE 06Z NAM BACKED OFF ITS EARLIER WARMER TEMPERATURES BUT IS STILL VERY MILD. HAVE KEPT THE MAXES THE NEARLY THE SAME BUT POTENTIAL THERE THAT MAXES COULD BE WARMER. LIGHT WINDS ON THE BACK SIDE OF THE SURFACE RIDGE DEVELOP OVER THE EASTERN HALF OR SO. BOUNDARY LAYER RH INCREASES IN THIS SAME AREA. AIR MASS LOOKS TO CHANGE LITTLE SO THAT MAKES SENSE. PREVIOUS FORECAST HAD FOG IN THERE AND LEFT THE FOG FORECAST ALONE. LIGHTER WINDS EAST WILL MAKE FOR COOLER MINS WITH WARMER MINS FURTHER WEST WITH DOWNSLOPING AND SOME WARM AIR ADVECTION. MONDAY/MONDAY NIGHT...LEFT THE MORNING FOG IN THERE. MAY HAVE SOME LOW LEVEL CLOUD COVER IN THERE WITH SOME INCREASE IN MID AND HIGH LEVEL CLOUD COVER. MODELS HAVE MAJOR DIFFERENCES IN THE AMOUNT OF WARMUP FOR THIS DAY. 06Z NAM HAS SLOWED ITS ARRIVAL OF THE COLD FRONT AND IS NOW NEAR TO SLIGHTLY SLOWER THAN THE ECMWF WHICH LOOKS BETTER IN HANDLING THIS. IN FACT THE ECMWF LOOKS THE FASTEST WITH REMAINING NEAR TO MUCH SLOWER THAN IT. AS A RESULT THE FRONT LOOKS TO ONLY MAKE IT INTO THE NORTHERN PORTION BY LATE IN THE DAY. IF THE CLOUDS DO NOT MESS UP THE TEMPERATURES...IT COULD END UP BEING VERY WARM ESPECIALLY IN THE SOUTHEAST HALF WHICH SHOULD GET THE WHOLE DAY OF HEATING. CONSIDERING THE TREND ON THE FRONTAL ARRIVAL AND THE INCREASE IN THE TEMPERATURE GUIDANCE...WARMED UP THE MAXES... ESPECIALLY IN THE SOUTHEAST WHICH COULD GET CLOSE TO 70. IF THIS SCENARIO PANS OUT...THE FAR WESTERN PORTION OF THE FORECAST AREA GETS CLOSE TO 20 PERCENT RELATIVE HUMIDITY AND GUSTS NEAR 25 MPH. THE DAY SHIFT WILL HAVE TO TAKE ANOTHER LOOK AT THIS. FRONT BLASTS THROUGH DURING THE NIGHT. GRADIENT AND RATHER HIGH 3 HOUR PRESSURE RISES WOULD INDICATE WINDY CONDITIONS DURING THE EVENING BEHIND THE FRONT. A RATHER STRONG SOUTHWEST TO NORTHEAST JET BEGINS TO MOVE ACROSS THE AREA DURING THE DAY AND EVENING. THIS PUTS THE SOUTHEAST HALF OF THE AREA IN THE RIGHT REAR QUADRANT DURING THE AFTERNOON AND INTO THE EVENING HOURS. EVEN THOUGH MAY BE HERE IN THE AFTERNOON...THE MOISTURE PROFILE DOES NOT SUPPORT ANY PRECIPITATION BEFORE 00Z. LIFT AND MOISTURE DO COME IN AFTER 00Z. HOWEVER THEY DO NOT SYNC UP WELL. THE LIFT AND EVEN SOME INSTABILITY ARE FURTHER TO THE EAST THAN THE DEEPEST MOISTURE. LIFT AND MOISTURE PROFILES MATCH UP WELL WITH THE DETERMINISTIC AND HPC QPF. THIS IS ALSO SUPPORTED BY THE GEFS/SREF PRECIPITATION PROBABILITIES. ALL THIS MEANS THAT THE NORTHWEST HALF WILL SEE THE BEST CHANCE OF PRECIPITATION. WITH ALL THE NEW DATA SUPPORTING THE CURRENT FORECAST VERY WELL...DID NOT MAKE ANY CHANGES TO IT. TUESDAY/TUESDAY NIGHT...AGAIN NEW GUIDANCE IS VERY SUPPORTIVE OF THE CHANCE OF PRECIPITATION/PRECIPITATION TYPE FORECAST THROUGH THE MORNING. SO LEFT THOSE GRIDS THROUGH 18Z ALONE. MOST OF THE LIFT AND MOISTURE IS GONE BY 18Z. LINGERING FLURRIES OR SPRINKLES IN THE AFTERNOON WILL BE MORE LIKELY THAN MEASURABLE SO MADE THAT CHANGE. COLD FRONT WILL BE SOUTH OF THE AREA BY THE BEGINNING OF THE DAY. DEFINITELY WILL BE COOLER WITH THE MODELS SURPRISINGLY IN GOOD AGREEMENT. PROBLEM IS THAT THE AGREEMENT IS WARMER THAN CURRENT FORECAST. WITH THE POSSIBILITY OF A DECENT AMOUNT OF SUN AND SOME DOWNSLOPE WINDS CAN DEFINITELY SEE THE WARMER TEMPERATURES. SO RAISED THE MAXES A LITTLE. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 419 AM MST SUN JAN 27 2013 MODEL GUIDANCE HAVING A HARD TIME CATCHING ONTO THE STRATUS AND FOG CURRENTLY AFFECTING BOTH TAF SITES. THE RUC BY FAR IS THE BEST MODEL. AT THIS TIME EXPECT IFR TO LIFR CONDITIONS THROUGH MID MORNING WITH KGLD HAVING THE WORST CONDITIONS. AFTER THAT CONDITIONS SHOULD IMPROVE TO MVFR BY LATE MORNING WITH VFR CONDITIONS PREVAILING NEAR OR SHORTLY AFTER 18Z OR 19Z. IN THE LATER PORTION OF THE PERIOD AT KMCK...FOG IS EXPECTED TO DEVELOP ONCE AGAIN. AT THIS TIME IT LOOKS LIKE THE FOG REMAINS EAST OF KGLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 9 AM MST /10 AM CST/ THIS MORNING FOR KSZ001>004-013>016. CO...DENSE FOG ADVISORY UNTIL 9 AM MST THIS MORNING FOR COZ090. NE...DENSE FOG ADVISORY UNTIL 9 AM MST /10 AM CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...JTL SHORT TERM...BULLER LONG TERM...JTL AVIATION...DDT
AREA FORECAST DISCUSSION
NWS GOODLAND KS
536 AM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 514 AM MST SUN JAN 27 2013 JUST ISSUED A DENSE FOG ADVISORY. AREAS OF DENSE FOG HAVE BECOME MORE WIDESPREAD OVER MOST OF EXTREME SOUTHWEST NEBRASKA AND THE FAR NORTH AND NORTHWEST PORTIONS OF NORTHWEST KANSAS. THESE CONDITIONS HAVE PERSISTED AND GOT WORSE. EVEN DESPITE OF DOWNSLOPE WINDS...ALBEIT LIGHT...THE DENSE FOG HAS CONTINUE. SMALL SCALE MODEL OUTPUT HAVING A DIFFICULT TIME GETTING A HANDLE ON THIS. RUC STARTED OUT WELL BUT IS NOW FADING. HRRR HAS BECOME MUCH BETTER IN DEPICTING THIS. SO IN ADDITION THE LOCATIONS ALREADY EXPERIENCING DENSE FOG...ALSO PUT THE ADVISORY INTO RED WILLOW AND NORTON COUNTIES PER OBSERVATIONAL TRENDS AND BEST MODEL OUTPUT. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 419 AM MST SUN JAN 27 2013 NUMEROUS FORECAST PROBLEMS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. FLOW IS SPLITTING OVER THE WESTERN PORTION OF THE COUNTRY. AN UNORGANIZED TROUGH WITH SMALLER WAVES WITHIN IT IS MOVING THROUGH THE AREA AT THIS TIME. THIS SYSTEM BROUGHT LIGHT RAIN TO THE AREA. THIS RAINFALL HAS MOVED NORTH OF THE AREA. MODELS INITIALIZED FINE ON THE JET. UPPER AIR ANALYSIS AND ESPECIALLY SATELLITE SHOWS THAT THE GFS AND ECMWF ARE HANDLING THE MID LEVELS THE BEST...ESPECIALLY IN OUR AREA. NAM DID NOT HAVE ANY PRECIPITATION OVER THE AREA TONIGHT. MODELS ARE HAVING A HARD TIME PLACING THE FOG AND STRATUS RIGHT NOW. MODELS WERE ALSO HAVING TROUBLE AT THE SURFACE. THE RUC AND ECMWF WERE DOING THE BEST. MODELS WERE CLOSE ON THE LOW LEVEL THERMAL FIELD WITH THE ECMWF AND UKMET DOING A LITTLE BETTER THAN THE GFS AND CANADIAN TODAY/TONIGHT...INITIAL PROBLEM WILL BE CLOUDS AND FOG. MODELS DOING A POOR JOB IN DEPICTING THIS REALITY AT THIS TIME. THE RUC AND TO A LESSER EXTENT THE HRRR IS GETTING THIS. PLAN ON WATCHING TRENDS AS LONG AS POSSIBLE BEFORE ADJUSTING THE BEST OUTPUT WITH THAT. MODELS HANG CLOUDS AROUND A WHILE. VERY DRY AIR PER SATELLITE AND ANALYSIS SHOULD QUICKLY WORK ITS WAY INTO THE AREA BY 18Z. SO EXPECT MOST OF THE CLOUD COVER AT ALL LEVELS TO BE GONE. LATEST GUIDANCE HAS BACKED OFF ON THE WINDS AND WILL ADJUST ACCORDINGLY. COMBINATION OF DOWNSLOPE WINDS AND LITTLE CLOUD COVER SHOULD ALLOW FOR A GOOD WARM UP. ANALYSIS SHOWS THAT AIR MASS WILL BE NEARLY THE SAME AS YESTERDAY. ALTHOUGH THE 06Z NAM BACKED OFF ITS EARLIER WARMER TEMPERATURES BUT IS STILL VERY MILD. HAVE KEPT THE MAXES THE NEARLY THE SAME BUT POTENTIAL THERE THAT MAXES COULD BE WARMER. LIGHT WINDS ON THE BACK SIDE OF THE SURFACE RIDGE DEVELOP OVER THE EASTERN HALF OR SO. BOUNDARY LAYER RH INCREASES IN THIS SAME AREA. AIR MASS LOOKS TO CHANGE LITTLE SO THAT MAKES SENSE. PREVIOUS FORECAST HAD FOG IN THERE AND LEFT THE FOG FORECAST ALONE. LIGHTER WINDS EAST WILL MAKE FOR COOLER MINS WITH WARMER MINS FURTHER WEST WITH DOWNSLOPING AND SOME WARM AIR ADVECTION. MONDAY/MONDAY NIGHT...LEFT THE MORNING FOG IN THERE. MAY HAVE SOME LOW LEVEL CLOUD COVER IN THERE WITH SOME INCREASE IN MID AND HIGH LEVEL CLOUD COVER. MODELS HAVE MAJOR DIFFERENCES IN THE AMOUNT OF WARMUP FOR THIS DAY. 06Z NAM HAS SLOWED ITS ARRIVAL OF THE COLD FRONT AND IS NOW NEAR TO SLIGHTLY SLOWER THAN THE ECMWF WHICH LOOKS BETTER IN HANDLING THIS. IN FACT THE ECMWF LOOKS THE FASTEST WITH REMAINING NEAR TO MUCH SLOWER THAN IT. AS A RESULT THE FRONT LOOKS TO ONLY MAKE IT INTO THE NORTHERN PORTION BY LATE IN THE DAY. IF THE CLOUDS DO NOT MESS UP THE TEMPERATURES...IT COULD END UP BEING VERY WARM ESPECIALLY IN THE SOUTHEAST HALF WHICH SHOULD GET THE WHOLE DAY OF HEATING. CONSIDERING THE TREND ON THE FRONTAL ARRIVAL AND THE INCREASE IN THE TEMPERATURE GUIDANCE...WARMED UP THE MAXES... ESPECIALLY IN THE SOUTHEAST WHICH COULD GET CLOSE TO 70. IF THIS SCENARIO PANS OUT...THE FAR WESTERN PORTION OF THE FORECAST AREA GETS CLOSE TO 20 PERCENT RELATIVE HUMIDITY AND GUSTS NEAR 25 MPH. THE DAY SHIFT WILL HAVE TO TAKE ANOTHER LOOK AT THIS. FRONT BLASTS THROUGH DURING THE NIGHT. GRADIENT AND RATHER HIGH 3 HOUR PRESSURE RISES WOULD INDICATE WINDY CONDITIONS DURING THE EVENING BEHIND THE FRONT. A RATHER STRONG SOUTHWEST TO NORTHEAST JET BEGINS TO MOVE ACROSS THE AREA DURING THE DAY AND EVENING. THIS PUTS THE SOUTHEAST HALF OF THE AREA IN THE RIGHT REAR QUADRANT DURING THE AFTERNOON AND INTO THE EVENING HOURS. EVEN THOUGH MAY BE HERE IN THE AFTERNOON...THE MOISTURE PROFILE DOES NOT SUPPORT ANY PRECIPITATION BEFORE 00Z. LIFT AND MOISTURE DO COME IN AFTER 00Z. HOWEVER THEY DO NOT SYNC UP WELL. THE LIFT AND EVEN SOME INSTABILITY ARE FURTHER TO THE EAST THAN THE DEEPEST MOISTURE. LIFT AND MOISTURE PROFILES MATCH UP WELL WITH THE DETERMINISTIC AND HPC QPF. THIS IS ALSO SUPPORTED BY THE GEFS/SREF PRECIPITATION PROBABILITIES. ALL THIS MEANS THAT THE NORTHWEST HALF WILL SEE THE BEST CHANCE OF PRECIPITATION. WITH ALL THE NEW DATA SUPPORTING THE CURRENT FORECAST VERY WELL...DID NOT MAKE ANY CHANGES TO IT. TUESDAY/TUESDAY NIGHT...AGAIN NEW GUIDANCE IS VERY SUPPORTIVE OF THE CHANCE OF PRECIPITATION/PRECIPITATION TYPE FORECAST THROUGH THE MORNING. SO LEFT THOSE GRIDS THROUGH 18Z ALONE. MOST OF THE LIFT AND MOISTURE IS GONE BY 18Z. LINGERING FLURRIES OR SPRINKLES IN THE AFTERNOON WILL BE MORE LIKELY THAN MEASURABLE SO MADE THAT CHANGE. COLD FRONT WILL BE SOUTH OF THE AREA BY THE BEGINNING OF THE DAY. DEFINITELY WILL BE COOLER WITH THE MODELS SURPRISINGLY IN GOOD AGREEMENT. PROBLEM IS THAT THE AGREEMENT IS WARMER THAN CURRENT FORECAST. WITH THE POSSIBILITY OF A DECENT AMOUNT OF SUN AND SOME DOWNSLOPE WINDS CAN DEFINITELY SEE THE WARMER TEMPERATURES. SO RAISED THE MAXES A LITTLE. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 419 AM MST SUN JAN 27 2013 MODEL GUIDANCE HAVING A HARD TIME CATCHING ONTO THE STRATUS AND FOG CURRENTLY AFFECTING BOTH TAF SITES. THE RUC BY FAR IS THE BEST MODEL. AT THIS TIME EXPECT IFR TO LIFR CONDITIONS THROUGH MID MORNING WITH KGLD HAVING THE WORST CONDITIONS. AFTER THAT CONDITIONS SHOULD IMPROVE TO MVFR BY LATE MORNING WITH VFR CONDITIONS PREVAILING NEAR OR SHORTLY AFTER 18Z OR 19Z. IN THE LATER PORTION OF THE PERIOD AT KMCK...FOG IS EXPECTED TO DEVELOP ONCE AGAIN. AT THIS TIME IT LOOKS LIKE THE FOG REMAINS EAST OF KGLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 9 AM MST /10 AM CST/ THIS MORNING FOR KSZ001>004-013-014. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 9 AM MST /10 AM CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...BULLER SHORT TERM...BULLER LONG TERM...JTL AVIATION...DDT
AREA FORECAST DISCUSSION
NWS GOODLAND KS
419 AM MST SUN JAN 27 2013 .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 419 AM MST SUN JAN 27 2013 NUMEROUS FORECAST PROBLEMS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. FLOW IS SPLITTING OVER THE WESTERN PORTION OF THE COUNTRY. AN UNORGANIZED TROUGH WITH SMALLER WAVES WITHIN IT IS MOVING THROUGH THE AREA AT THIS TIME. THIS SYSTEM BROUGHT LIGHT RAIN TO THE AREA. THIS RAINFALL HAS MOVED NORTH OF THE AREA. MODELS INITIALIZED FINE ON THE JET. UPPER AIR ANALYSIS AND ESPECIALLY SATELLITE SHOWS THAT THE GFS AND ECMWF ARE HANDLING THE MID LEVELS THE BEST...ESPECIALLY IN OUR AREA. NAM DID NOT HAVE ANY PRECIPITATION OVER THE AREA TONIGHT. MODELS ARE HAVING A HARD TIME PLACING THE FOG AND STRATUS RIGHT NOW. MODELS WERE ALSO HAVING TROUBLE AT THE SURFACE. THE RUC AND ECMWF WERE DOING THE BEST. MODELS WERE CLOSE ON THE LOW LEVEL THERMAL FIELD WITH THE ECMWF AND UKMET DOING A LITTLE BETTER THAN THE GFS AND CANADIAN TODAY/TONIGHT...INITIAL PROBLEM WILL BE CLOUDS AND FOG. MODELS DOING A POOR JOB IN DEPICTING THIS REALITY AT THIS TIME. THE RUC AND TO A LESSER EXTENT THE HRRR IS GETTING THIS. PLAN ON WATCHING TRENDS AS LONG AS POSSIBLE BEFORE ADJUSTING THE BEST OUTPUT WITH THAT. MODELS HANG CLOUDS AROUND A WHILE. VERY DRY AIR PER SATELLITE AND ANALYSIS SHOULD QUICKLY WORK ITS WAY INTO THE AREA BY 18Z. SO EXPECT MOST OF THE CLOUD COVER AT ALL LEVELS TO BE GONE. LATEST GUIDANCE HAS BACKED OFF ON THE WINDS AND WILL ADJUST ACCORDINGLY. COMBINATION OF DOWNSLOPE WINDS AND LITTLE CLOUD COVER SHOULD ALLOW FOR A GOOD WARM UP. ANALYSIS SHOWS THAT AIR MASS WILL BE NEARLY THE SAME AS YESTERDAY. ALTHOUGH THE 06Z NAM BACKED OFF ITS EARLIER WARMER TEMPERATURES BUT IS STILL VERY MILD. HAVE KEPT THE MAXES THE NEARLY THE SAME BUT POTENTIAL THERE THAT MAXES COULD BE WARMER. LIGHT WINDS ON THE BACK SIDE OF THE SURFACE RIDGE DEVELOP OVER THE EASTERN HALF OR SO. BOUNDARY LAYER RH INCREASES IN THIS SAME AREA. AIR MASS LOOKS TO CHANGE LITTLE SO THAT MAKES SENSE. PREVIOUS FORECAST HAD FOG IN THERE AND LEFT THE FOG FORECAST ALONE. LIGHTER WINDS EAST WILL MAKE FOR COOLER MINS WITH WARMER MINS FURTHER WEST WITH DOWNSLOPING AND SOME WARM AIR ADVECTION. MONDAY/MONDAY NIGHT...LEFT THE MORNING FOG IN THERE. MAY HAVE SOME LOW LEVEL CLOUD COVER IN THERE WITH SOME INCREASE IN MID AND HIGH LEVEL CLOUD COVER. MODELS HAVE MAJOR DIFFERENCES IN THE AMOUNT OF WARMUP FOR THIS DAY. 06Z NAM HAS SLOWED ITS ARRIVAL OF THE COLD FRONT AND IS NOW NEAR TO SLIGHTLY SLOWER THAN THE ECMWF WHICH LOOKS BETTER IN HANDLING THIS. IN FACT THE ECMWF LOOKS THE FASTEST WITH REMAINING NEAR TO MUCH SLOWER THAN IT. AS A RESULT THE FRONT LOOKS TO ONLY MAKE IT INTO THE NORTHERN PORTION BY LATE IN THE DAY. IF THE CLOUDS DO NOT MESS UP THE TEMPERATURES...IT COULD END UP BEING VERY WARM ESPECIALLY IN THE SOUTHEAST HALF WHICH SHOULD GET THE WHOLE DAY OF HEATING. CONSIDERING THE TREND ON THE FRONTAL ARRIVAL AND THE INCREASE IN THE TEMPERATURE GUIDANCE...WARMED UP THE MAXES... ESPECIALLY IN THE SOUTHEAST WHICH COULD GET CLOSE TO 70. IF THIS SCENARIO PANS OUT...THE FAR WESTERN PORTION OF THE FORECAST AREA GETS CLOSE TO 20 PERCENT RELATIVE HUMIDITY AND GUSTS NEAR 25 MPH. THE DAY SHIFT WILL HAVE TO TAKE ANOTHER LOOK AT THIS. FRONT BLASTS THROUGH DURING THE NIGHT. GRADIENT AND RATHER HIGH 3 HOUR PRESSURE RISES WOULD INDICATE WINDY CONDITIONS DURING THE EVENING BEHIND THE FRONT. A RATHER STRONG SOUTHWEST TO NORTHEAST JET BEGINS TO MOVE ACROSS THE AREA DURING THE DAY AND EVENING. THIS PUTS THE SOUTHEAST HALF OF THE AREA IN THE RIGHT REAR QUADRANT DURING THE AFTERNOON AND INTO THE EVENING HOURS. EVEN THOUGH MAY BE HERE IN THE AFTERNOON...THE MOISTURE PROFILE DOES NOT SUPPORT ANY PRECIPITATION BEFORE 00Z. LIFT AND MOISTURE DO COME IN AFTER 00Z. HOWEVER THEY DO NOT SYNC UP WELL. THE LIFT AND EVEN SOME INSTABILITY ARE FURTHER TO THE EAST THAN THE DEEPEST MOISTURE. LIFT AND MOISTURE PROFILES MATCH UP WELL WITH THE DETERMINISTIC AND HPC QPF. THIS IS ALSO SUPPORTED BY THE GEFS/SREF PRECIPITATION PROBABILITIES. ALL THIS MEANS THAT THE NORTHWEST HALF WILL SEE THE BEST CHANCE OF PRECIPITATION. WITH ALL THE NEW DATA SUPPORTING THE CURRENT FORECAST VERY WELL...DID NOT MAKE ANY CHANGES TO IT. TUESDAY/TUESDAY NIGHT...AGAIN NEW GUIDANCE IS VERY SUPPORTIVE OF THE CHANCE OF PRECIPITATION/PRECIPITATION TYPE FORECAST THROUGH THE MORNING. SO LEFT THOSE GRIDS THROUGH 18Z ALONE. MOST OF THE LIFT AND MOISTURE IS GONE BY 18Z. LINGERING FLURRIES OR SPRINKLES IN THE AFTERNOON WILL BE MORE LIKELY THAN MEASURABLE SO MADE THAT CHANGE. COLD FRONT WILL BE SOUTH OF THE AREA BY THE BEGINNING OF THE DAY. DEFINITELY WILL BE COOLER WITH THE MODELS SURPRISINGLY IN GOOD AGREEMENT. PROBLEM IS THAT THE AGREEMENT IS WARMER THAN CURRENT FORECAST. WITH THE POSSIBILITY OF A DECENT AMOUNT OF SUN AND SOME DOWNSLOPE WINDS CAN DEFINITELY SEE THE WARMER TEMPERATURES. SO RAISED THE MAXES A LITTLE. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 419 AM MST SUN JAN 27 2013 MODEL GUIDANCE HAVING A HARD TIME CATCHING ONTO THE STRATUS AND FOG CURRENTLY AFFECTING BOTH TAF SITES. THE RUC BY FAR IS THE BEST MODEL. AT THIS TIME EXPECT IFR TO LIFR CONDITIONS THROUGH MID MORNING WITH KGLD HAVING THE WORST CONDITIONS. AFTER THAT CONDITIONS SHOULD IMPROVE TO MVFR BY LATE MORNING WITH VFR CONDITIONS PREVAILING NEAR OR SHORTLY AFTER 18Z OR 19Z. IN THE LATER PORTION OF THE PERIOD AT KMCK...FOG IS EXPECTED TO DEVELOP ONCE AGAIN. AT THIS TIME IT LOOKS LIKE THE FOG REMAINS EAST OF KGLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...JTL AVIATION...DDT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
528 AM EST SUN JAN 27 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 421 PM EST SAT JAN 26 2013 LAKE EFFECT HAS BEEN GRADUALLY DIMINISHING THROUGH THE AFTERNOON HOURS...AS THE NORTHERLY FLOW HAS SLOWED WITH HIGH PRESSURE MOVING OVER THE CWA. STILL HAVE SOME LIGHT SNOW SHOWERS OVER THE NORTH CENTRAL CWA...BUT EXPECT THEM TO END OR PUSH NORTH DURING THE LATE AFTERNOON AND EARLY EVENING. OTHERWISE...A FAIRLY NICE AFTERNOON WITH LIGHT WINDS AND TEMPERATURES AT OR SLIGHTLY BELOW NORMAL AS OF 3PM. HIGH PRESSURE CENTERED OVER THE UPPER GREAT LAKES WILL SHIFT EAST TONIGHT AS THE UPPER RIDGE BUILDS NORTHEAST INTO THE UPPER MISSISSIPPI VALLEY. AS THIS OCCURS...BROAD H800-600 WARM AIR ADVECTION CURRENTLY IN MINNESOTA AND STARTING TO MOVE INTO WESTERN LAKE SUPERIOR WILL CONTINUE EAST ACROSS THE CWA TONIGHT. SO FAR TODAY...HAVE ONLY SEEN A FEW OBS REPORTING SNOW SHOWERS FROM THIS MID CLOUD DECK IN NORTHERN MN...WHICH WAS LIKELY HELD OFF BY DRY H925-850 AIR SEEN ON 12Z KINL SOUNDING AND RUC SOUNDINGS IN THAT AREA. LATEST MODELS DO TRY TO MOISTEN THE CENTRAL CWA TOWARDS MIDNIGHT...AS THE STRONGER H925-850 WAA SLIDES EAST ALONG THE WI BORDER. NOT LIKING HOW QUICKLY THINGS MOISTEN...BUT WITH THE IDEA IN SEVERAL MODELS...WILL ADD SLIGHT CHANCES THERE. WILL KEEP THE BEST POPS OVER THE NORTHERN HALF OF LAKE SUPERIOR WHERE THE LOWER LEVELS WERE A LITTLE MORE MOIST AND THE MID LEVEL WAA WAS THE STRONGEST. ALSO ADDED A MENTION OF FLURRIES TO AREAS SURROUNDING THE POPS TO ACCOUNT FOR SOME SNOW MAKING IT THROUGH THE DRY AIR. THE OTHER ITEM OF CONCERN HEADING INTO THE OVERNIGHT HOURS WILL BE THE INCREASED MOISTENING OF THE LOWER LEVELS OFF LAKE MICHIGAN. AS THIS OCCURS...THE H850 TEMPS WILL BE WARMING TOWARDS -10C OVERNIGHT...SO DON/T EXPECT LAKE ENHANCEMENT TO GET TOO OUT OF HAND. BUT WITH THE SNOW ALOFT FEEDING INTO THE LOWER LEVELS FORCING THAT IS MAINLY BELOW -10C...EXPECT SNOW TO DEVELOP THERE. H925 WINDS ARE FAVORABLE FOR SOUTHERN LUCE AND SOUTHEAST SCHOOLCRAFT...SO HAVE INCREASED POPS INTO LOW END LIKELY VALUES FOR THOSE LOCATIONS AND TAPERED IT OFF FAIRLY QUICKLY TO THE WEST. WITH SNOW RATIOS ON THE LOW END...AROUND 10-14 TO 1 INITIALLY AND TRENDING TOWARDS 8-1 SUNDAY MORNING...EXPECT ACCUMULATIONS TO BE FAIRLY LIGHT IN THOSE AREAS WITH ONLY AN INCH OF ACCUMULATION. THE LAKE EFFECT SHOULD DIMINISH LATER SUNDAY MORNING INTO THE EARLY AFTERNOON DUE TO THE CONTINUED WARMING OF TEMPS ALOFT SHOVING INVERSION HEIGHTS TO 3KFT. SUNDAY LOOKS TO BE FAIRLY QUIET...AS THE AREA IS BETWEEN THE EXITING WARM AIR ADVECTION PRECIPITATION AND THE NEXT APPROACHING SYSTEM FOR SUNDAY NIGHT. THE NEXT WAVE IS CURRENTLY OVER SOUTHERN CALIFORNIA AND QUICKLY MOVES NORTHEAST AND TOWARDS THE AREA TONIGHT AND SUNDAY. WITH THE INCREASED CONSISTENCY IN THE MODELS...HAVE DELAYED THE START OF THE PRECIPITATION UNTIL 00Z AND LATER. THE LONG TERM DISCUSSION WILL COVER THIS SYSTEM IN FURTHER DETAILS. OTHERWISE...WILL SEE A GAP IN THE CLOUDS BEHIND THE WAA CLOUDS DEPARTING IN THE MORNING AND THE INCREASING CLOUDS FROM THE SOUTHWEST IN THE AFTERNOON. THINK THIS CLEARING WILL BE MOST LIKELY OVER THE WEST HALF AND HAVE TRENDED TOWARDS PARTLY-MOSTLY SUNNY SKY FOR PERIOD AROUND MID DAY. FARTHER EAST...NAM/GFS ARE HINTING AT SOME LOWER CLOUDS DEVELOPING TONIGHT AND REMAINING THROUGH MUCH OF SUNDAY. NOT OVERLY CONFIDENT ON THIS SOLUTION WITH THE DRY AIR UPSTREAM...BUT WITH THE EXITING MID CLOUDS AND APPROACHING HIGH CLOUDS...A PARTLY-MOSTLY CLOUDY FORECAST SEEMED WARRANTED. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 527 AM EST SUN JAN 27 2013 AT 12Z MONDAY A HIGH AMPLITUDE RIDGE WILL ENCOMPASS MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE U.S...WITH A SMALL BUT VERY SIGNIFICANT WAVE STRETCHING FROM LAKE SUPERIOR TO N WI. THE LARGER TROUGH WILL BE SET UP FROM SASKATCHEWAN THROUGH ID AND S CA. ZONAL FLOW WILL QUICKLY TURN TO SW FLOW ALOFT MONDAY AFTERNOON AHEAD OF THE NEARING WESTERN TROUGH. THE VAIL OF PRECIP OVERHEAD MONDAY MORNING WILL QUICKLY EXIT EAST DURING THE DAY MONDAY...WITH FREEZING DRIZZLE AND/OR SNOW AT THE TAIL END. WARM AIR WILL CONTINUE TO PUSH INTO THE AREA DURING THE DAY MONDAY...WITH 850MB TEMPS RISING TO 3-5C NEAR THE WI BORDER...AS SFC TEMPS JUMP ABOVE FREEZING /33-37F/. EXPECT THE N END OF THE TROUGH ACROSS SASKATCHEWAN MONDAY TO CLOSE OFF OVER CENTRAL MANITOBA MONDAY NIGHT...AND DEEPEN ACROSS ONTARIO TUESDAY NIGHT...WITH THE TROUGH EXTENDING S FROM THE LOW ALL THE WAY THROUGH TX. SOME UNCERTAINLY REMAIN IN THE MERGING OF THE N AND S STREAM TROUGHS...WITH THE SFC REFLECTIONS OVER W ONTARIO AND NE KS AT 06Z TUESDAY. THESE 2 SFC LOWS ARE EXPECTED TO MERGE NEAR THE CWA TUESDAY MORNING INTO EARLY TUESDAY AFTERNOON...BEFORE QUICKLY EJECTING NE TUESDAY AFTERNOON/EVENING. ANOTHER ROUND OF POSSIBLE FREEZING RAIN/DRIZZLE WILL BE POSSIBLE LATE TUESDAY. S FLOW OFF LAKE SUPERIOR AND ACROSS AREAS TO S MAY LEAD TO ANOTHER ROUGH OF FREEZING DRIZZLE. AMOUNTS SHOULD REMAIN LIGHT...WITH ONLY A COUPLE HUNDREDTHS ANTICIPATED AT THIS TIME...AS HIGHS WARM INTO THE MID TO UPPER 30S TUESDAY AFTERNOON. MIN TEMPS TUESDAY WILL BE NEARLY IDENTICAL TO HIGH TEMPS FORECAST FOR WEDNESDAY...DUE TO THE SLOW COOL DOWN EXPECTED THROUGH THE DAY WEDNESDAY. WEDNESDAY COULD ALSO BE A BIT BREEZY AS COLD AIR WRAPS AROUND THE EXITING LOW. THE PROGRESSIVE 500MB LOW WILL CONTINUE TO DEEPEN NEAR JAMES BAY WEDNESDAY NIGHT...WITH THE TROUGH ENCOMPASSING MUCH OF THE U.S. THIS WILL BRING THE RETURN OF NW FLOW ALOFT...FROM LATE WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FCST PERIOD. THE RESULT WILL BE SEVERAL DIFFICULT TO TIME WAVES WILL PUSH ACROSS THE AREA FROM THURSDAY THROUGH SATURDAY...AND BEYOND...AS WELL AS A RETURN TO NEAR OR BELOW NORMAL TEMPERATURES. 850MB TEMPS WILL PLUMMET TO AROUND -20C WEDNESDAY EVENING...AND CONTINUE TO FALL TO -22 TO -25C FROM THURSDAY EVENING THROUGH FRIDAY. CONTINUED TO HIGHLIGHT THE W FACING SLOPES OF W UPPER MI...AND AREAS E OF MUNISING NEAR LAKE SUPERIOR FOR THE BEST CHANCE OF SNOW GIVEN THE NW WINDS. SFC-850MB WINDS SHOULD BECOME MORE WESTERLY FRIDAY...SLOWLY PUSHING THE BEST CHANCE OF CONTINUED LES N TO THE TIP OF THE KEWEENAW PENINSULA...AND JUST OFFSHORE ACROSS E UPPER MI. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1242 AM EST SUN JAN 27 2013 VFR CONDITIONS WILL CONTINUE AT ALL SITES THROUGH SUNDAY. BY SUNDAY EVENING...NEXT SYSTEM STARTS TO AFFECT THE AREA AND WILL BRING IN SOME MVFR VIS AND CIGS WITH SOME LIGHT SNOW. THERE COULD BE A BRIEF PERIOD OF -SHSN OR FLURRIES AT KCMX/KSAW OVERNIGHT...BUT IT SHOULDN/T AFFECT VISIBILITIES OVERNIGHT. THESE CLOUDS SHOULD PUSH EAST ON SUNDAY MORNING AND JUST LEAVE SOME PASSING MID CLOUDS. DID PUT A MENTION OF SCATTERED LOW CLOUDS AT KSAW TOMORROW MORNING...SINCE THE MODELS ARE HINTING AT THAT POSSIBILITY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 421 PM EST SAT JAN 26 2013 HIGH PRESSURE CURRENTLY OVERHEAD WILL SHIFT EAST TONIGHT AND LEAD TO INCREASING SOUTHERLY WINDS...BUT EXPECT GUSTS TO REMAIN BELOW 25KTS. WINDS WILL REMAIN BELOW 25KTS THROUGH THE FIRST COUPLE OF DAYS OF THE UPCOMING WORK WEEK DUE TO WEAK PRESSURE GRADIENTS. A LOW MOVING THROUGH THE GREAT LAKES ON TUESDAY AND THEN INCREASING IN INTENSITY OVER EASTERN CANADA WILL PRODUCE INCREASING NORTHERLY WINDS TO 30KTS TUESDAY NIGHT INTO WEDNESDAY. THIS...COMBINED WITH COLDER AIR SURGING SOUTH...WILL LEAD TO FREEZING SPRAY FOR THE MIDDLE AND END OF THE WORK WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 1 PM EST MONDAY FOR MIZ006-007-085. WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO 10 AM EST /9 AM CST/ MONDAY FOR MIZ005-010-011. WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO 11 AM EST /10 AM CST/ MONDAY FOR MIZ012>014. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...KF AVIATION...07 MARINE...SRF
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
938 AM CST SUN JAN 27 2013 .DISCUSSION... HAVE MADE SEVERAL UPDATES TO THE GRIDS THIS MORNING TO REFLECT ONGOING WEATHER TRENDS. WITH SURFACE LOW AT 15Z CENTERED IN WESTERN KS/SOUTHEAST CO...DRY SLOT IS EDGING INTO SOUTHERN/SOUTHEAST NEB THIS MORNING. PRECIP IS JUST ABOUT OUT OF WESTERN IA...BUT SHOULD LINGER IN THE WRAPAROUND AREA IN NORTHEAST NEB INTO THE AFTERNOON. THE DRY SLOT HAS FILLED WITH LOW CIGS AND PATCHY FOG...BUT THINK THIS SHOULD IMPROVE THIS AFTERNOON. HAVE UPDATED CLOUDS TO BE EVEN MORE PESSIMISTIC...WHILE UPDATING WEATHER GRIDS TO REFLECT MORE DRIZZLE THAN RAIN AS SYSTEM EXITS /EXCEPT IN NORTHEAST NEB/. ALSO CUT MAX TEMP FORECAST IN THE SOUTHERN CWA...AS WARM NOSE AHEAD OF THE LOW IS BEING OFFSET BY CLOUDS. KEPT MENTION FOR AREAS OF FOG TONIGHT AS LOW-LEVEL MOISTURE MAY NOT SCOUR OUT UNDER WEAK LOW-LEVEL WINDS. MAYES && .PREV DISCUSSION... /ISSUED 554 AM CST SUN JAN 27 2013/ AVIATION...12Z TAFS FOR KOFK...KOMA AND KLNK. PRIMARILY IFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES FOR MUCH OF THIS FORECAST PERIOD. THE GOOD NEWS...RAIN EVENT DEVELOPED AND MOVED ACROSS THE FORECAST AREA THIS MORNING WITH TEMPERATURES WARM ENOUGH TO KEEP RAIN FROM FREEZING. AFTER A BRIEF LULL DUE TO DRY SLOT MOVING ACROSS THE AREA...CONDITIONS QUICKLY FILLED IN BEHIND EXITING SYSTEM WITH WIDESPREAD IFR CIGS. AT THIS TIME CIGS AND VSBYS FORECAST TO BECOME MVFR AFTER 06Z TIME FRAME. I REMAIN CONCERNED ABOUT POSSIBLE IFR VSBYS LATE IN FORECAST PERIOD DUE TO WEAK WEST FLOW WHICH NORMALLY IS NOT GOOD AT SCOURING OUT LINGERING LOW LEVEL MOISTURE AND FOG. MEYER PREV DISCUSSION... /ISSUED 233 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY. HERE COMES THE RAIN. SURFACE TEMPERATURES HAVE REMAINED ABOVE FREEZING THROUGH THE NIGHT AND WILL REMAIN THAT WAY THROUGH THE DAY...THUS NO THREAT FOR FREEZING RAIN IN OUR FORECAST AREA THIS MORNING. PRETTY SOLID BAND OF RAIN WILL CONTINUE TO PUSH TO THE NORTH THIS MORNING AND THROUGH MOST OF THE FORECAST AREA BY EARLY THIS AFTERNOON. A DEFINITIVE SOUTHERN EDGE WILL LIKELY EVEN CLEAR SOUTHEAST NEBRASKA BEFORE 6 AM BASED ON LATEST RAP HOURLY DATA. ONCE THE HEAVIER SHOWERS MOVE OUT...STRATUS WILL LIKELY PREVAIL FOR THE AFTERNOON WITH AREAS OF DRIZZLE MAINLY ALONG AND NORTH OF INTERSTATE 80...WHICH THEN PUSHES NORTHEAST OUT OF THE AREA THROUGH THE EVENING. THERE COULD BE SOME BRIEF CLEARING BEHIND THIS BY LATE EVENING. AT THAT POINT...BELIEVE WE WILL FOG BACK IN THROUGH DAYBREAK MONDAY...WITH THE LOW LEVEL MOISTURE NOT REALLY BEING SCRUBBED OUT. WINDS GO VERY LIGHT OR EVEN CALM IN MOST AREAS BY 09-12Z MONDAY...WITH BOTH MAV/MET GUIDANCE SUGGESTING WIDESPREAD FOG DEVELOPING...AND POSSIBLY DENSE IN MANY AREAS. THIS WOULD PROBABLY LINGER INTO EARLY MONDAY MORNING...AND WOULD NOT BE SURPRISED IF A DENSE FOG ADVISORY MAY EVENTUALLY BE NEEDED. OF SOME CONCERN WOULD BE SURFACE TEMPERATURES DROPPING TO NEAR OR BELOW FREEZING MONDAY MORNING ALONG AND NORTH OF I80...WHICH COULD RESULT IN SLICK ROADWAYS FOR THE MORNING COMMUTE. MONDAY IS A BIT OF A TRANSITION DAY WITH MUCH OF THE MID MISSOURI VALLEY IN BETWEEN SYSTEMS. THE SURFACE WARM FRONT MAY LIFT BACK TO THE NORTH TO NEAR I80 THROUGH THE DAY. MEANWHILE...THE NEXT TROUGH MOVING THROUGH THE NORTHERN ROCKIES SHOULD START TO SPREAD DEEPER MOISTURE INTO NORTHEAST NEBRASKA BY MONDAY AFTERNOON...BUT CERTAINLY MONDAY NIGHT. AT THE SAME TIME...AN ADVANCING COLD FRONT WILL ALSO BE USHERING IN COLDER AIR TO NORTHEAST NEBRASKA. SHOULD SEE RAIN MIX WITH AND CHANGE TO SNOW ACROSS NORTHEAST NEBRASKA...AND GIVEN THAT THIS IS OCCURRING AT NIGHT COULD PROBABLY EVEN SEEM SOME MINOR ACCUMULATIONS OF AN INCH UP THERE BY DAYBREAK TUESDAY. FURTHER SOUTH ALONG AND SOUTH OF I80...PRECIP POTENTIAL IS MORE MORE QUESTIONABLE...BUT WILL MAINTAIN SLIGHT CHANCE POPS THAT LINGER INTO TUESDAY AS WELL...BUT CERTAINLY COULD ALSO BE DRY ACROSS ALL AREAS BUT NORTHEAST NEBRASKA. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. A TRANSITION TO A COLDER ARCTIC AIR MASS WILL CONTINUE EARLY IN THE PERIOD WITH THE FIRST REINFORCING SHOT OF COLDER AIR OVERSPREADING THE AREA ON WEDNESDAY WITH BLUSTERY NORTHWEST WINDS. HIGHS WILL BE BACK IN THE UPPER TEENS NORTH TO UPPER 20S SOUTH...BUT COLDER FEELING WITH THE WINDS. THE GFS HAS HINTED AT SOME FLURRY POTENTIAL ACROSS NORTHEAST NEBRASKA AS H85 TEMPERATURES APPROACH THE DENDRITIC RANGE...BUT THE ECMWF IS STILL DRY. SECOND AND COLDER REINFORCING SURGE ARRIVES BY THURSDAY...AGAIN WITH CONTINUED NORTHWEST BLUSTERY CONDITIONS. EVEN COLDER TEMPS WELL WITHIN THE DENDRITIC RANGE WOULD SUGGEST SOME FLURRY POTENTIAL AGAIN WITH HIGHS EVEN COLDER IN THE LOWER TEENS NORTH TO MID 20S SOUTH...WITH WIND CHILLS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO ONCE AGAIN. SURFACE HIGH MOVES OVER THE AREA THURSDAY NIGHT RESULTING IN LOWS IN THE SINGLE DIGITS ONE MORE TIME. FRIDAY AND SATURDAY SHOULD BE TRANSITION DAYS BACK TO WARMER TEMPS AGAIN WEST WESTERLY FLOW...DRY CONDITIONS AND HIGHS BACK INTO THE MID TO UPPER 40S FOR THE WEEKEND. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS HASTINGS NE
847 AM CST SUN JAN 27 2013 .UPDATE... VISIBILITIES CONTINUE TO DECAY. SO ISSUED A DENSE FOG ADVISORY UNTIL NOON. FOG WILL LINGER IN SOME AREAS PAST NOON...BUT VSBYS WILL IMPROVE TO MORE THAN A QUARTER MILE. NPW/ZFP ARE OUT. HWO/EHWO WILL POST SHORTLY. && .PREV DISCUSSION... /ISSUED 631 AM CST SUN JAN 27 2013/ AVIATION...12Z KGRI TAF. WILL STATE OFF THE TOP THAT THIS WILL BE A CHALLENGING 24 HOURS IN TERMS OF PINNING DOWN THE TIMING OF CEILING/VISIBILITY CHANGES...BUT THE BOTTOM LINE IS THAT A GOOD CHUNK OF THE PERIOD WILL SEE DEGRADED FLIGHT CATEGORIES RANGING BETWEEN LIFR AND MVFR. STARTING OFF RIGHT AWAY THIS MORNING...IFR/LIFR CONDITIONS ARE FIRMLY IN PLACE...AND THIS IS LIKELY TO PERSIST THROUGH MOST/ALL OF THE MORNING HOURS AS A SATURATED LOW LEVEL AIRMASS PERSISTS IN THE PRESENCE OF LIGHT SOUTHERLY BREEZES. WOULD NOT BE SURPRISED TO EVEN SEE A BRIEF PERIOD OF VLIFR CONDITIONS IN DENSE FOG. THIS AFTERNOON...ANTICIPATE VISIBILITY TO GRADUALLY IMPROVE INTO MVFR THEN VFR TERRITORY...WHILE CEILING TRENDS GRADUALLY IMPROVE TO LOW-END MVFR BY MID-LATE AFTERNOON. AS LOW LEVEL FLOW TURNS MORE WESTERLY LATE IN THE AFTERNOON/EARLY THIS EVENING ...HAVE REASONABLE CONFIDENCE THAT THERE SHOULD BE AT LEAST A 6 HOUR PERIOD OF VFR CONDITIONS AS THE LOW LEVEL CEILING FINALLY LIFTS/SCATTERS OUT. ATTENTION THEN TURNS TO THE LATE NIGHT HOURS...WHEN A LIGHT AND VARIABLE WIND REGIME ALONG WITH WET GROUND WILL LIKELY FOSTER THE REDEVELOPMENT OF FOG...ALTHOUGH TO WHAT EXTENT IS STILL UNKNOWN. FOR NOW...WILL ADVERTISE PREVAILING IFR CONDITIONS DURING THE LAST FEW HOURS OF THE PERIOD...AND DEFER TO LATER FORECASTS TO FINE TUNE THE DETAILS. PREV DISCUSSION... /ISSUED 449 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT. MOST OF THE MEASURABLE RAIN WILL HAVE EXITED OUR CWA TO THE NORTHEAST BY SUNRISE...BUT DRIZZLE AND FOG WILL STILL BE A FACTOR FOR SOME AREAS TODAY. THE TEMPERATURE FORECAST IS A BIG CHALLENGE...BUT EXPECT GENERALLY ABOVE NORMAL TEMPERATURES THROUGH TUESDAY. A SECOND STORM SYSTEM WILL ENTER OUR FORECAST AREA MONDAY NIGHT AND BRING WITH IT A CHALLENGING MIXED PRECIPITATION TYPE FORECAST. TODAY...THERE ARE NUMEROUS FORECAST CONCERNS CENTERED AROUND POSSIBLE FOG...A STRATUS DECK THAT WILL BE DIFFICULT TO SHAKE ESPECIALLY ACROSS NEBRASKA ZONES...A SHARP TEMPERATURE GRADIENT...AND EVEN SOME PATCHY DRIZZLE. THE SREF AND HRRR ARE BOTH INDICATING THE POSSIBILITY OF FOG BEHIND THE DEPARTING RAIN BAND WITH THE POTENTIAL OF VISIBILITY REDUCTIONS TO LESS THAN ONE QUARTER MILE. THIS FOG HAS YET TO MATERIALIZE THUS FAR THIS MORNING...BUT CEILING HEIGHTS HAVE BEEN FALLING AND THE WIND WILL BEGIN TO DIE DOWN SOME ACROSS OUR WEST AFTER SUNRISE. THEREFORE...WILL CONTINUE TO INCLUDE POSSIBLE FOG IN OUR FORECAST FOR THIS MORNING. THERE HAS BEEN SOME DRIZZLE BEHIND THE RAIN BAND AND THIS IS ALSO LIKELY TO CONTINUE THROUGH AT LEAST A PORTION OF THE MORNING ESPECIALLY ACROSS EASTERN ZONES. THE DRIZZLE MAY EVEN LINGER OVER OUR FAR EAST THROUGH EARLY THIS AFTERNOON. MOST FORECAST MODELS BRING THE CLEARING LINE INTO KANSAS THIS AFTERNOON BUT KEEP MOST NEBRASKA ZONES SOCKED IN UNDER A LOW STRATUS DECK. THUS THERE WILL BE A TIGHT TEMPERATURE GRADIENT ALONG THE EDGE OF THIS STRATUS DECK...WHICH SHOULD BE LOCATED SOMEWHERE NEAR THE NEBRASKA KANSAS BORDER THIS AFTERNOON. TONIGHT...THE WET GROUND FROM THE RECENT RAIN ALONG WITH LIGHT AND VARIABLE WINDS WILL MAKE FOG POSSIBLE. THEREFORE...WILL CONTINUE TO CALL FOR AT LEAST THE POSSIBILITY OF SOME FOG LATE TONIGHT INTO EARLY MONDAY MORNING. MONDAY...THE NEXT UPPER TROUGH WILL BE DIGGING ACROSS THE WESTERN CONUS WITH AN ASSOCIATED SFC LOW DEVELOPING OVER EASTERN COLORADO. THE WIND WILL BE SOUTHERLY ACROSS THE PLAINS AHEAD OF THIS LOW AND WE SHOULD WARM UP NICELY WITH HIGH TEMPERATURES POTENTIALLY WELL ABOVE NORMAL. HOWEVER...THERE IS UNCERTAINTY IN THE LOW CLOUD FORECAST ON MONDAY...WHICH IF PRESENT...THESE LOW CLOUDS WOULD REALLY HAMPER OUR WARM UP. MONDAY NIGHT INTO TUESDAY...THE UPPER WAVE AND SFC LOW WILL PRESS THROUGH OUR FORECAST AREA WITH A COLD FRONT SWEEPING THROUGH. THIS IS A PROGRESSIVE FAST MOVING OPEN WAVE. THUS ANY DEFORMATION SNOW BAND WILL BE WEAK WITH LITTLE IF ANY SNOW ACCUMULATION. THE 00Z ECMWF AND 00Z GFS PLACE A BAND OF RAIN AND SNOW ACROSS OUR NORTHWEST ZONES MONDAY EVENING...WHICH SHOULD TURN OVER TO ALL SNOW AT SOME POINT AFTER MIDNIGHT. THIS BAND HEADS MORE NORTHEAST RATHER THAN SOUTHEAST...AND OUR SOUTHEAST ZONES MAY STAY COMPLETELY DRY. THE MOST AGGRESSIVE MODEL GENERALLY IS CALLING FOR ONE INCH OR LESS OF SNOW ACROSS OUR NORTHWEST...SO THIS IS NOT APPEARING TO BE A BIG DEAL FOR OUR AREA. TUESDAY WILL BE COOLER BEHIND THE COLD FRONT...BUT STILL ABOVE NORMAL AS THE COLDER AIR WILL TAKE SOME TIME TO SETTLE IN. LONG TERM...WEDNESDAY THROUGH SATURDAY. OVERALL NO MAJOR CHANGES TO THESE 4 DAYS FROM PREVIOUS FORECAST...ALTHOUGH A SLIGHT CHANCE OF SNOW HAS BEEN INTRODUCED FOR PARTS OF THE CWA THURSDAY...AND HIGH TEMPS FOR FRIDAY CONTINUE TO TREND UP A BIT. CONFIDENCE IS FAIRLY HIGH THAT THE MAJORITY OF THIS TIME FRAME IS PRECIPITATION FREE EXCEPT FOR MAYBE THURSDAY...WHICH ALSO LOOKS LIKE THE COLDEST DAY OF THE UPCOMING WEEK. STARTING OFF WEDNESDAY/WED NIGHT...00Z ECMWF/GFS RUNS ARE IN GOOD AGREEMENT ON THE BIG PICTURE. ALOFT DURING THE DAY...THE LOCAL AREA WILL SEE NORTHWEST FLOW BEHIND THE DEPARTURE OF A LARGE SCALE TROUGH AXIS THAT EXTENDS NORTH-SOUTH THROUGH THE HEART OF THE NATION...WITH THIS TROUGH AXIS PROGRESSING EAST TOWARD THE EASTERN MIDWEST/OHIO VALLEY REGION BY DAYS END. THEN ON WED NIGHT...A SHORTWAVE TROUGH DROPS SOUTHWARD OUT OF CANADA INTO THE DAKOTAS...REINFORCING THE TROUGHY PATTERN DOMINATING THE MAJORITY OF THE CONUS BY THIS TIME. CONFIDENCE IS FAIRLY HIGH IN A PRECIPITATION-FREE 24 HOURS HERE...AT LEAST OF THE MEASURABLE VARIETY...ALTHOUGH WOULD NOT BE SURPRISED TO SEE A FEW FLURRIES STILL BRUSHING EASTERN ZONES DURING THE DAY...AND THEN ANOTHER BATCH OF FLURRIES/LIGHT SNOW POSSIBLY APPROACHING NORTHERN/WESTERN COUNTIES LATE WEDNESDAY NIGHT...BUT BOTH OF THESE POSSIBILITIES SEEM LOW ENOUGH FOR NOW TO LEAVE OUT. TEMP-WISE...MADE VERY LITTLE IF ANY CHANGE TO PREVIOUS FORECAST...AS WEDNESDAY SHOULD BE ROUGHLY 10 DEGREES COOLER THAN TUESDAY IN THE WAKE OF THE FIRST OF TWO MID-WEEK COLD FRONTS. HIGHS ARE AIMED TO RANGE FROM MID-UPPER 20S FAR NORTHEAST...NEAR 30 TRI-CITIES...MID- UPPER 30S SOUTHWEST. THURSDAY/THURS NIGHT...HAVE INTRODUCED A SLIGHT CHANCE OF SNOW FOR ROUGHLY THE SOUTHWEST 1/3 OF THE CWA FOR THE DAYTIME HOURS...AND WOULD NOT BE SURPRISED TO SEE THIS SLIGHT CHANCE OF SNOW OR AT LEAST FLURRIES EXPANDED TO COVER MORE OF OUR AREA IN LATER FORECASTS IF TRENDS FROM THE 00Z ECMWF/GEM CONTINUE. IN SHORT...THIS LOOKS LIKE A FAVORABLE SETUP FOR A QUICK-HITTING MINOR SNOW ACCUMULATION...AS THE AFOREMENTIONED NORTHWEST-FLOW SHORTWAVE TROUGH THAT DROPS INTO THE DAKOTAS WED NIGHT CONTINUES TO SINK SOUTHEAST ACROSS EASTERN NEB/IA ON THURSDAY...AND A NORTH- SOUTH ORIENTED UPPER JET STREAK APPROACHES OUR LOCAL AREA FROM THE NORTHWEST...HELPING FOCUS A BAND OF MID LEVEL LIFT/SATURATION. NOT LOOKING LIKE HIGH-IMPACT BY ANY MEANS...BUT SOMETHING TO KEEP AN EYE ON. BY THURSDAY NIGHT...FORCING FOR ANY NUISANCE SNOW SHOULD HAVE MOVED OFF TO THE SOUTHEAST. IN THE LOW LEVELS...THE SECOND AND STRONGER COLD FRONT OF THE WEEK ENTERS THE CWA DURING THE DAY...ALTHOUGH THE CORE OF THE TRULY COLD AIR SHOULD REMAIN AT LEAST A FEW HUNDRED MILES TO OUR NORTHEAST...MUCH AS SEEN WITHIN THE PAST WEEK. CERTAINLY THIS WILL RESULT IN A SHARP AND HARD-TO- PIN-DOWN SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT FOR HIGHS ON THURSDAY...AND HAVE SHAVED A COUPLE DEGREES OFF PREVIOUS FORECAST ALL AREAS...AIMING FOR A RANGE FROM NEAR 20 FAR NORTHEAST...MID- UPPER 20S TRI-CITIES AND MID 30S SOUTHWEST. MUCH COLDER AIR WILL NOT BE FAR AWAY...WITH SINGLE DIGIT HIGHS POSSIBLY AS CLOSE AS FAR NORTHEAST NEB...SO WOULD NOT BE SURPRISED TO SEE THIS COLDER AIR PUSH SOUTHWEST INTO OUR AREA A BIT MORE AGGRESSIVELY THAN CURRENTLY ADVERTISED. FRIDAY/FRIDAY NIGHT...THE REGION REMAINS IN WEST-NORTHWEST FLOW ALOFT...AS A COUPLE SHORTWAVE TROUGHS PASS THROUGH THE FLOW...ONE STAYING WELL NORTH FROM CANADA INTO THE NORTHERN GREAT LAKES...AND THE OTHER SLIDING INTO OR JUST SOUTHWEST OF THE AREA. AT THIS TIME...NOTHING APPEARS STRONG ENOUGH TO GENERATE PRECIP FOR OUR CWA. THE BIGGER STORY IS A POTENTIALLY DECENT WARM-UP OVER THURSDAY...AS THE COLD LOW LEVEL RIDGE AXIS SLIDES EAST AND ALLOWS WARMER AIR TO INVADE THE CENTRAL PLAINS ON WESTERLY OR SOUTHERLY BREEZES. HAVE RAISED FRIDAY HIGHS 3-4 DEGREES FROM PREVIOUS FORECAST PER MULTI-MODEL ALLBLEND...NOW RANGING FROM MID 30S NORTHEAST TO LOW-MID 40S SOUTHWEST. SATURDAY CURRENTLY HAS RATHER HIGH CONFIDENCE OF BEING PRECIP-FREE...AND IS ALSO LOOKING LIKE THE WARMEST DAY SINCE MONDAY...AND MADE ALMOST NO CHANGE TO PREVIOUS HIGHS RANGING FROM MID 40S NORTHEAST TO UPPER 40S/LOW 50S SOUTH AND WEST. THE ECWMF SUGGESTS THERE COULD BE A DECENT NORTHWEST BREEZE AS THE REGION IS GLANCED BY A THE EDGES OF A WEAK COLD FRONT DRIVEN BY ANOTHER GREAT LAKES SHORTWAVE TROUGH...BUT EVEN SO DECENT MIXING AND A DOWNSLOPE WIND COMPONENT WOULD HELP AID A WARM-UP. && .GID WATCHES/WARNINGS/ADVISORIES... NE...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NEZ039>041-046>049- 060>064-072>077-082>086. KS...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR KSZ005-006-017. && $$ UPDATE...HALBLAUB SHORT TERM...WESELY AVIATION...PFANNCUCH LONG TERM...PFANNCUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
631 AM CST SUN JAN 27 2013 .AVIATION...12Z KGRI TAF. WILL STATE OFF THE TOP THAT THIS WILL BE A CHALLENGING 24 HOURS IN TERMS OF PINNING DOWN THE TIMING OF CEILING/VISIBILITY CHANGES...BUT THE BOTTOM LINE IS THAT A GOOD CHUNK OF THE PERIOD WILL SEE DEGRADED FLIGHT CATEGORIES RANGING BETWEEN LIFR AND MVFR. STARTING OFF RIGHT AWAY THIS MORNING...IFR/LIFR CONDITIONS ARE FIRMLY IN PLACE...AND THIS IS LIKELY TO PERSIST THROUGH MOST/ALL OF THE MORNING HOURS AS A SATURATED LOW LEVEL AIRMASS PERSISTS IN THE PRESENCE OF LIGHT SOUTHERLY BREEZES. WOULD NOT BE SURPRISED TO EVEN SEE A BRIEF PERIOD OF VLIFR CONDITIONS IN DENSE FOG. THIS AFTERNOON...ANTICIPATE VISIBILITY TO GRADUALLY IMPROVE INTO MVFR THEN VFR TERRITORY...WHILE CEILING TRENDS GRADUALLY IMPROVE TO LOW-END MVFR BY MID-LATE AFTERNOON. AS LOW LEVEL FLOW TURNS MORE WESTERLY LATE IN THE AFTERNOON/EARLY THIS EVENING ...HAVE REASONABLE CONFIDENCE THAT THERE SHOULD BE AT LEAST A 6 HOUR PERIOD OF VFR CONDITIONS AS THE LOW LEVEL CEILING FINALLY LIFTS/SCATTERS OUT. ATTENTION THEN TURNS TO THE LATE NIGHT HOURS...WHEN A LIGHT AND VARIABLE WIND REGIME ALONG WITH WET GROUND WILL LIKELY FOSTER THE REDEVELOPMENT OF FOG...ALTHOUGH TO WHAT EXTENT IS STILL UNKNOWN. FOR NOW...WILL ADVERTISE PREVAILING IFR CONDITIONS DURING THE LAST FEW HOURS OF THE PERIOD...AND DEFER TO LATER FORECASTS TO FINE TUNE THE DETAILS. && .PREV DISCUSSION... /ISSUED 449 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT. MOST OF THE MEASURABLE RAIN WILL HAVE EXITED OUR CWA TO THE NORTHEAST BY SUNRISE...BUT DRIZZLE AND FOG WILL STILL BE A FACTOR FOR SOME AREAS TODAY. THE TEMPERATURE FORECAST IS A BIG CHALLENGE...BUT EXPECT GENERALLY ABOVE NORMAL TEMPERATURES THROUGH TUESDAY. A SECOND STORM SYSTEM WILL ENTER OUR FORECAST AREA MONDAY NIGHT AND BRING WITH IT A CHALLENGING MIXED PRECIPITATION TYPE FORECAST. TODAY...THERE ARE NUMEROUS FORECAST CONCERNS CENTERED AROUND POSSIBLE FOG...A STRATUS DECK THAT WILL BE DIFFICULT TO SHAKE ESPECIALLY ACROSS NEBRASKA ZONES...A SHARP TEMPERATURE GRADIENT...AND EVEN SOME PATCHY DRIZZLE. THE SREF AND HRRR ARE BOTH INDICATING THE POSSIBILITY OF FOG BEHIND THE DEPARTING RAIN BAND WITH THE POTENTIAL OF VISIBILITY REDUCTIONS TO LESS THAN ONE QUARTER MILE. THIS FOG HAS YET TO MATERIALIZE THUS FAR THIS MORNING...BUT CEILING HEIGHTS HAVE BEEN FALLING AND THE WIND WILL BEGIN TO DIE DOWN SOME ACROSS OUR WEST AFTER SUNRISE. THEREFORE...WILL CONTINUE TO INCLUDE POSSIBLE FOG IN OUR FORECAST FOR THIS MORNING. THERE HAS BEEN SOME DRIZZLE BEHIND THE RAIN BAND AND THIS IS ALSO LIKELY TO CONTINUE THROUGH AT LEAST A PORTION OF THE MORNING ESPECIALLY ACROSS EASTERN ZONES. THE DRIZZLE MAY EVEN LINGER OVER OUR FAR EAST THROUGH EARLY THIS AFTERNOON. MOST FORECAST MODELS BRING THE CLEARING LINE INTO KANSAS THIS AFTERNOON BUT KEEP MOST NEBRASKA ZONES SOCKED IN UNDER A LOW STRATUS DECK. THUS THERE WILL BE A TIGHT TEMPERATURE GRADIENT ALONG THE EDGE OF THIS STRATUS DECK...WHICH SHOULD BE LOCATED SOMEWHERE NEAR THE NEBRASKA KANSAS BORDER THIS AFTERNOON. TONIGHT...THE WET GROUND FROM THE RECENT RAIN ALONG WITH LIGHT AND VARIABLE WINDS WILL MAKE FOG POSSIBLE. THEREFORE...WILL CONTINUE TO CALL FOR AT LEAST THE POSSIBILITY OF SOME FOG LATE TONIGHT INTO EARLY MONDAY MORNING. MONDAY...THE NEXT UPPER TROUGH WILL BE DIGGING ACROSS THE WESTERN CONUS WITH AN ASSOCIATED SFC LOW DEVELOPING OVER EASTERN COLORADO. THE WIND WILL BE SOUTHERLY ACROSS THE PLAINS AHEAD OF THIS LOW AND WE SHOULD WARM UP NICELY WITH HIGH TEMPERATURES POTENTIALLY WELL ABOVE NORMAL. HOWEVER...THERE IS UNCERTAINTY IN THE LOW CLOUD FORECAST ON MONDAY...WHICH IF PRESENT...THESE LOW CLOUDS WOULD REALLY HAMPER OUR WARM UP. MONDAY NIGHT INTO TUESDAY...THE UPPER WAVE AND SFC LOW WILL PRESS THROUGH OUR FORECAST AREA WITH A COLD FRONT SWEEPING THROUGH. THIS IS A PROGRESSIVE FAST MOVING OPEN WAVE. THUS ANY DEFORMATION SNOW BAND WILL BE WEAK WITH LITTLE IF ANY SNOW ACCUMULATION. THE 00Z ECMWF AND 00Z GFS PLACE A BAND OF RAIN AND SNOW ACROSS OUR NORTHWEST ZONES MONDAY EVENING...WHICH SHOULD TURN OVER TO ALL SNOW AT SOME POINT AFTER MIDNIGHT. THIS BAND HEADS MORE NORTHEAST RATHER THAN SOUTHEAST...AND OUR SOUTHEAST ZONES MAY STAY COMPLETELY DRY. THE MOST AGGRESSIVE MODEL GENERALLY IS CALLING FOR ONE INCH OR LESS OF SNOW ACROSS OUR NORTHWEST...SO THIS IS NOT APPEARING TO BE A BIG DEAL FOR OUR AREA. TUESDAY WILL BE COOLER BEHIND THE COLD FRONT...BUT STILL ABOVE NORMAL AS THE COLDER AIR WILL TAKE SOME TIME TO SETTLE IN. LONG TERM...WEDNESDAY THROUGH SATURDAY. OVERALL NO MAJOR CHANGES TO THESE 4 DAYS FROM PREVIOUS FORECAST...ALTHOUGH A SLIGHT CHANCE OF SNOW HAS BEEN INTRODUCED FOR PARTS OF THE CWA THURSDAY...AND HIGH TEMPS FOR FRIDAY CONTINUE TO TREND UP A BIT. CONFIDENCE IS FAIRLY HIGH THAT THE MAJORITY OF THIS TIME FRAME IS PRECIPITATION FREE EXCEPT FOR MAYBE THURSDAY...WHICH ALSO LOOKS LIKE THE COLDEST DAY OF THE UPCOMING WEEK. STARTING OFF WEDNESDAY/WED NIGHT...00Z ECMWF/GFS RUNS ARE IN GOOD AGREEMENT ON THE BIG PICTURE. ALOFT DURING THE DAY...THE LOCAL AREA WILL SEE NORTHWEST FLOW BEHIND THE DEPARTURE OF A LARGE SCALE TROUGH AXIS THAT EXTENDS NORTH-SOUTH THROUGH THE HEART OF THE NATION...WITH THIS TROUGH AXIS PROGRESSING EAST TOWARD THE EASTERN MIDWEST/OHIO VALLEY REGION BY DAYS END. THEN ON WED NIGHT...A SHORTWAVE TROUGH DROPS SOUTHWARD OUT OF CANADA INTO THE DAKOTAS...REINFORCING THE TROUGHY PATTERN DOMINATING THE MAJORITY OF THE CONUS BY THIS TIME. CONFIDENCE IS FAIRLY HIGH IN A PRECIPITATION-FREE 24 HOURS HERE...AT LEAST OF THE MEASURABLE VARIETY...ALTHOUGH WOULD NOT BE SURPRISED TO SEE A FEW FLURRIES STILL BRUSHING EASTERN ZONES DURING THE DAY...AND THEN ANOTHER BATCH OF FLURRIES/LIGHT SNOW POSSIBLY APPROACHING NORTHERN/WESTERN COUNTIES LATE WEDNESDAY NIGHT...BUT BOTH OF THESE POSSIBILITIES SEEM LOW ENOUGH FOR NOW TO LEAVE OUT. TEMP-WISE...MADE VERY LITTLE IF ANY CHANGE TO PREVIOUS FORECAST...AS WEDNESDAY SHOULD BE ROUGHLY 10 DEGREES COOLER THAN TUESDAY IN THE WAKE OF THE FIRST OF TWO MID-WEEK COLD FRONTS. HIGHS ARE AIMED TO RANGE FROM MID-UPPER 20S FAR NORTHEAST...NEAR 30 TRI-CITIES...MID- UPPER 30S SOUTHWEST. THURSDAY/THURS NIGHT...HAVE INTRODUCED A SLIGHT CHANCE OF SNOW FOR ROUGHLY THE SOUTHWEST 1/3 OF THE CWA FOR THE DAYTIME HOURS...AND WOULD NOT BE SURPRISED TO SEE THIS SLIGHT CHANCE OF SNOW OR AT LEAST FLURRIES EXPANDED TO COVER MORE OF OUR AREA IN LATER FORECASTS IF TRENDS FROM THE 00Z ECMWF/GEM CONTINUE. IN SHORT...THIS LOOKS LIKE A FAVORABLE SETUP FOR A QUICK-HITTING MINOR SNOW ACCUMULATION...AS THE AFOREMENTIONED NORTHWEST-FLOW SHORTWAVE TROUGH THAT DROPS INTO THE DAKOTAS WED NIGHT CONTINUES TO SINK SOUTHEAST ACROSS EASTERN NEB/IA ON THURSDAY...AND A NORTH- SOUTH ORIENTED UPPER JET STREAK APPROACHES OUR LOCAL AREA FROM THE NORTHWEST...HELPING FOCUS A BAND OF MID LEVEL LIFT/SATURATION. NOT LOOKING LIKE HIGH-IMPACT BY ANY MEANS...BUT SOMETHING TO KEEP AN EYE ON. BY THURSDAY NIGHT...FORCING FOR ANY NUISANCE SNOW SHOULD HAVE MOVED OFF TO THE SOUTHEAST. IN THE LOW LEVELS...THE SECOND AND STRONGER COLD FRONT OF THE WEEK ENTERS THE CWA DURING THE DAY...ALTHOUGH THE CORE OF THE TRULY COLD AIR SHOULD REMAIN AT LEAST A FEW HUNDRED MILES TO OUR NORTHEAST...MUCH AS SEEN WITHIN THE PAST WEEK. CERTAINLY THIS WILL RESULT IN A SHARP AND HARD-TO- PIN-DOWN SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT FOR HIGHS ON THURSDAY...AND HAVE SHAVED A COUPLE DEGREES OFF PREVIOUS FORECAST ALL AREAS...AIMING FOR A RANGE FROM NEAR 20 FAR NORTHEAST...MID- UPPER 20S TRI-CITIES AND MID 30S SOUTHWEST. MUCH COLDER AIR WILL NOT BE FAR AWAY...WITH SINGLE DIGIT HIGHS POSSIBLY AS CLOSE AS FAR NORTHEAST NEB...SO WOULD NOT BE SURPRISED TO SEE THIS COLDER AIR PUSH SOUTHWEST INTO OUR AREA A BIT MORE AGGRESSIVELY THAN CURRENTLY ADVERTISED. FRIDAY/FRIDAY NIGHT...THE REGION REMAINS IN WEST-NORTHWEST FLOW ALOFT...AS A COUPLE SHORTWAVE TROUGHS PASS THROUGH THE FLOW...ONE STAYING WELL NORTH FROM CANADA INTO THE NORTHERN GREAT LAKES...AND THE OTHER SLIDING INTO OR JUST SOUTHWEST OF THE AREA. AT THIS TIME...NOTHING APPEARS STRONG ENOUGH TO GENERATE PRECIP FOR OUR CWA. THE BIGGER STORY IS A POTENTIALLY DECENT WARM-UP OVER THURSDAY...AS THE COLD LOW LEVEL RIDGE AXIS SLIDES EAST AND ALLOWS WARMER AIR TO INVADE THE CENTRAL PLAINS ON WESTERLY OR SOUTHERLY BREEZES. HAVE RAISED FRIDAY HIGHS 3-4 DEGREES FROM PREVIOUS FORECAST PER MULTI-MODEL ALLBLEND...NOW RANGING FROM MID 30S NORTHEAST TO LOW-MID 40S SOUTHWEST. SATURDAY CURRENTLY HAS RATHER HIGH CONFIDENCE OF BEING PRECIP-FREE...AND IS ALSO LOOKING LIKE THE WARMEST DAY SINCE MONDAY...AND MADE ALMOST NO CHANGE TO PREVIOUS HIGHS RANGING FROM MID 40S NORTHEAST TO UPPER 40S/LOW 50S SOUTH AND WEST. THE ECWMF SUGGESTS THERE COULD BE A DECENT NORTHWEST BREEZE AS THE REGION IS GLANCED BY A THE EDGES OF A WEAK COLD FRONT DRIVEN BY ANOTHER GREAT LAKES SHORTWAVE TROUGH...BUT EVEN SO DECENT MIXING AND A DOWNSLOPE WIND COMPONENT WOULD HELP AID A WARM-UP. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...WESELY LONG TERM/AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
554 AM CST SUN JAN 27 2013 .AVIATION...12Z TAFS FOR KOFK...KOMA AND KLNK. PRIMARILY IFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES FOR MUCH OF THIS FORECAST PERIOD. THE GOOD NEWS...RAIN EVENT DEVELOPED AND MOVED ACROSS THE FORECAST AREA THIS MORNING WITH TEMPERATURES WARM ENOUGH TO KEEP RAIN FROM FREEZING. AFTER A BRIEF LULL DUE TO DRY SLOT MOVING ACROSS THE AREA...CONDITIONS QUICKLY FILLED IN BEHIND EXITING SYSTEM WITH WIDESPREAD IFR CIGS. AT THIS TIME CIGS AND VSBYS FORECAST TO BECOME MVFR AFTER 06Z TIME FRAME. I REMAIN CONCERNED ABOUT POSSIBLE IFR VSBYS LATE IN FORECAST PERIOD DUE TO WEAK WEST FLOW WHICH NORMALLY IS NOT GOOD AT SCOURING OUT LINGERING LOW LEVEL MOISTURE AND FOG. MEYER && .PREV DISCUSSION... /ISSUED 233 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY. HERE COMES THE RAIN. SURFACE TEMPERATURES HAVE REMAINED ABOVE FREEZING THROUGH THE NIGHT AND WILL REMAIN THAT WAY THROUGH THE DAY...THUS NO THREAT FOR FREEZING RAIN IN OUR FORECAST AREA THIS MORNING. PRETTY SOLID BAND OF RAIN WILL CONTINUE TO PUSH TO THE NORTH THIS MORNING AND THROUGH MOST OF THE FORECAST AREA BY EARLY THIS AFTERNOON. A DEFINITIVE SOUTHERN EDGE WILL LIKELY EVEN CLEAR SOUTHEAST NEBRASKA BEFORE 6 AM BASED ON LATEST RAP HOURLY DATA. ONCE THE HEAVIER SHOWERS MOVE OUT...STRATUS WILL LIKELY PREVAIL FOR THE AFTERNOON WITH AREAS OF DRIZZLE MAINLY ALONG AND NORTH OF INTERSTATE 80...WHICH THEN PUSHES NORTHEAST OUT OF THE AREA THROUGH THE EVENING. THERE COULD BE SOME BRIEF CLEARING BEHIND THIS BY LATE EVENING. AT THAT POINT...BELIEVE WE WILL FOG BACK IN THROUGH DAYBREAK MONDAY...WITH THE LOW LEVEL MOISTURE NOT REALLY BEING SCRUBBED OUT. WINDS GO VERY LIGHT OR EVEN CALM IN MOST AREAS BY 09-12Z MONDAY...WITH BOTH MAV/MET GUIDANCE SUGGESTING WIDESPREAD FOG DEVELOPING...AND POSSIBLY DENSE IN MANY AREAS. THIS WOULD PROBABLY LINGER INTO EARLY MONDAY MORNING...AND WOULD NOT BE SURPRISED IF A DENSE FOG ADVISORY MAY EVENTUALLY BE NEEDED. OF SOME CONCERN WOULD BE SURFACE TEMPERATURES DROPPING TO NEAR OR BELOW FREEZING MONDAY MORNING ALONG AND NORTH OF I80...WHICH COULD RESULT IN SLICK ROADWAYS FOR THE MORNING COMMUTE. MONDAY IS A BIT OF A TRANSITION DAY WITH MUCH OF THE MID MISSOURI VALLEY IN BETWEEN SYSTEMS. THE SURFACE WARM FRONT MAY LIFT BACK TO THE NORTH TO NEAR I80 THROUGH THE DAY. MEANWHILE...THE NEXT TROUGH MOVING THROUGH THE NORTHERN ROCKIES SHOULD START TO SPREAD DEEPER MOISTURE INTO NORTHEAST NEBRASKA BY MONDAY AFTERNOON...BUT CERTAINLY MONDAY NIGHT. AT THE SAME TIME...AN ADVANCING COLD FRONT WILL ALSO BE USHERING IN COLDER AIR TO NORTHEAST NEBRASKA. SHOULD SEE RAIN MIX WITH AND CHANGE TO SNOW ACROSS NORTHEAST NEBRASKA...AND GIVEN THAT THIS IS OCCURRING AT NIGHT COULD PROBABLY EVEN SEEM SOME MINOR ACCUMULATIONS OF AN INCH UP THERE BY DAYBREAK TUESDAY. FURTHER SOUTH ALONG AND SOUTH OF I80...PRECIP POTENTIAL IS MORE MORE QUESTIONABLE...BUT WILL MAINTAIN SLIGHT CHANCE POPS THAT LINGER INTO TUESDAY AS WELL...BUT CERTAINLY COULD ALSO BE DRY ACROSS ALL AREAS BUT NORTHEAST NEBRASKA. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. A TRANSITION TO A COLDER ARCTIC AIR MASS WILL CONTINUE EARLY IN THE PERIOD WITH THE FIRST REINFORCING SHOT OF COLDER AIR OVERSPREADING THE AREA ON WEDNESDAY WITH BLUSTERY NORTHWEST WINDS. HIGHS WILL BE BACK IN THE UPPER TEENS NORTH TO UPPER 20S SOUTH...BUT COLDER FEELING WITH THE WINDS. THE GFS HAS HINTED AT SOME FLURRY POTENTIAL ACROSS NORTHEAST NEBRASKA AS H85 TEMPERATURES APPROACH THE DENDRITIC RANGE...BUT THE ECMWF IS STILL DRY. SECOND AND COLDER REINFORCING SURGE ARRIVES BY THURSDAY...AGAIN WITH CONTINUED NORTHWEST BLUSTERY CONDITIONS. EVEN COLDER TEMPS WELL WITHIN THE DENDRITIC RANGE WOULD SUGGEST SOME FLURRY POTENTIAL AGAIN WITH HIGHS EVEN COLDER IN THE LOWER TEENS NORTH TO MID 20S SOUTH...WITH WIND CHILLS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO ONCE AGAIN. SURFACE HIGH MOVES OVER THE AREA THURSDAY NIGHT RESULTING IN LOWS IN THE SINGLE DIGITS ONE MORE TIME. FRIDAY AND SATURDAY SHOULD BE TRANSITION DAYS BACK TO WARMER TEMPS AGAIN WEST WESTERLY FLOW...DRY CONDITIONS AND HIGHS BACK INTO THE MID TO UPPER 40S FOR THE WEEKEND. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS HASTINGS NE
449 AM CST SUN JAN 27 2013 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT. MOST OF THE MEASURABLE RAIN WILL HAVE EXITED OUR CWA TO THE NORTHEAST BY SUNRISE...BUT DRIZZLE AND FOG WILL STILL BE A FACTOR FOR SOME AREAS TODAY. THE TEMPERATURE FORECAST IS A BIG CHALLENGE...BUT EXPECT GENERALLY ABOVE NORMAL TEMPERATURES THROUGH TUESDAY. A SECOND STORM SYSTEM WILL ENTER OUR FORECAST AREA MONDAY NIGHT AND BRING WITH IT A CHALLENGING MIXED PRECIPITATION TYPE FORECAST. TODAY...THERE ARE NUMEROUS FORECAST CONCERNS CENTERED AROUND POSSIBLE FOG...A STRATUS DECK THAT WILL BE DIFFICULT TO SHAKE ESPECIALLY ACROSS NEBRASKA ZONES...A SHARP TEMPERATURE GRADIENT...AND EVEN SOME PATCHY DRIZZLE. THE SREF AND HRRR ARE BOTH INDICATING THE POSSIBILITY OF FOG BEHIND THE DEPARTING RAIN BAND WITH THE POTENTIAL OF VISIBILITY REDUCTIONS TO LESS THAN ONE QUARTER MILE. THIS FOG HAS YET TO MATERIALIZE THUS FAR THIS MORNING...BUT CEILING HEIGHTS HAVE BEEN FALLING AND THE WIND WILL BEGIN TO DIE DOWN SOME ACROSS OUR WEST AFTER SUNRISE. THEREFORE...WILL CONTINUE TO INCLUDE POSSIBLE FOG IN OUR FORECAST FOR THIS MORNING. THERE HAS BEEN SOME DRIZZLE BEHIND THE RAIN BAND AND THIS IS ALSO LIKELY TO CONTINUE THROUGH AT LEAST A PORTION OF THE MORNING ESPECIALLY ACROSS EASTERN ZONES. THE DRIZZLE MAY EVEN LINGER OVER OUR FAR EAST THROUGH EARLY THIS AFTERNOON. MOST FORECAST MODELS BRING THE CLEARING LINE INTO KANSAS THIS AFTERNOON BUT KEEP MOST NEBRASKA ZONES SOCKED IN UNDER A LOW STRATUS DECK. THUS THERE WILL BE A TIGHT TEMPERATURE GRADIENT ALONG THE EDGE OF THIS STRATUS DECK...WHICH SHOULD BE LOCATED SOMEWHERE NEAR THE NEBRASKA KANSAS BORDER THIS AFTERNOON. TONIGHT...THE WET GROUND FROM THE RECENT RAIN ALONG WITH LIGHT AND VARIABLE WINDS WILL MAKE FOG POSSIBLE. THEREFORE...WILL CONTINUE TO CALL FOR AT LEAST THE POSSIBILITY OF SOME FOG LATE TONIGHT INTO EARLY MONDAY MORNING. MONDAY...THE NEXT UPPER TROUGH WILL BE DIGGING ACROSS THE WESTERN CONUS WITH AN ASSOCIATED SFC LOW DEVELOPING OVER EASTERN COLORADO. THE WIND WILL BE SOUTHERLY ACROSS THE PLAINS AHEAD OF THIS LOW AND WE SHOULD WARM UP NICELY WITH HIGH TEMPERATURES POTENTIALLY WELL ABOVE NORMAL. HOWEVER...THERE IS UNCERTAINTY IN THE LOW CLOUD FORECAST ON MONDAY...WHICH IF PRESENT...THESE LOW CLOUDS WOULD REALLY HAMPER OUR WARM UP. MONDAY NIGHT INTO TUESDAY...THE UPPER WAVE AND SFC LOW WILL PRESS THROUGH OUR FORECAST AREA WITH A COLD FRONT SWEEPING THROUGH. THIS IS A PROGRESSIVE FAST MOVING OPEN WAVE. THUS ANY DEFORMATION SNOW BAND WILL BE WEAK WITH LITTLE IF ANY SNOW ACCUMULATION. THE 00Z ECMWF AND 00Z GFS PLACE A BAND OF RAIN AND SNOW ACROSS OUR NORTHWEST ZONES MONDAY EVENING...WHICH SHOULD TURN OVER TO ALL SNOW AT SOME POINT AFTER MIDNIGHT. THIS BAND HEADS MORE NORTHEAST RATHER THAN SOUTHEAST...AND OUR SOUTHEAST ZONES MAY STAY COMPLETELY DRY. THE MOST AGGRESSIVE MODEL GENERALLY IS CALLING FOR ONE INCH OR LESS OF SNOW ACROSS OUR NORTHWEST...SO THIS IS NOT APPEARING TO BE A BIG DEAL FOR OUR AREA. TUESDAY WILL BE COOLER BEHIND THE COLD FRONT...BUT STILL ABOVE NORMAL AS THE COLDER AIR WILL TAKE SOME TIME TO SETTLE IN. .LONG TERM...WEDNESDAY THROUGH SATURDAY. OVEERALL NO MAJOR CHANGES TO THESE 4 DAYS FROM PREVIOUS FORECAST...ALTHOUGH A SLIGHT CHANCE OF SNOW HAS BEEN INTRODUCED FOR PARTS OF THE CWA THURSDAY...AND HIGH TEMPS FOR FRIDAY CONTINUE TO TREND UP A BIT. CONFIDENCE IS FAIRLY HIGH THAT THE MAJORITY OF THIS TIME FRAME IS PRECIPITATION FREE EXCEPT FOR MAYBE THURSDAY...WHICH ALSO LOOKS LIKE THE COLDEST DAY OF THE UPCOMING WEEK. STARTING OFF WEDNESDAY/WED NIGHT...00Z ECMWF/GFS RUNS ARE IN GOOD AGREEMENT ON THE BIG PICTURE. ALOFT DURING THE DAY...THE LOCAL AREA WILL SEE NORTHWEST FLOW BEHIND THE DEPARTURE OF A LARGE SCALE TROUGH AXIS THAT EXTENDS NORTH-SOUTH THROUGH THE HEART OF THE NATION...WITH THIS TROUGH AXIS PROGRESSING EAST TOWARD THE EASTERN MIDWEST/OHIO VALLEY REGION BY DAYS END. THEN ON WED NIGHT...A SHORTWAVE TROUGH DROPS SOUTHWARD OUT OF CANADA INTO THE DAKOTAS...REINFORCING THE TROUGHY PATTERN DOMINATING THE MAJORITY OF THE CONUS BY THIS TIME. CONFIDENCE IS FAIRLY HIGH IN A PRECIPITATION-FREE 24 HOURS HERE...AT LEAST OF THE MEASURABLE VARIETY...ALTHOUGH WOULD NOT BE SURPRISED TO SEE A FEW FLURRIES STILL BRUSHING EASTERN ZONES DURING THE DAY...AND THEN ANOTHER BATCH OF FLURRIES/LIGHT SNOW POSSIBLY APPROACHING NORTHERN/WESTERN COUNTIES LATE WEDNESDAY NIGHT...BUT BOTH OF THESE POSSIBILITIES SEEM LOW ENOUGH FOR NOW TO LEAVE OUT. TEMP-WISE...MADE VERY LITTLE IF ANY CHANGE TO PREVIOUS FORECAST...AS WEDNESDAY SHOULD BE ROUGHLY 10 DEGREES COOLER THAN TUESDAY IN THE WAKE OF THE FIRST OF TWO MID-WEEK COLD FRONTS. HIGHS ARE AIMED TO RANGE FROM MID-UPPER 20S FAR NORTHEAST...NEAR 30 TRI-CITIES...MID- UPPER 30S SOUTHWEST. THURSDAY/THURS NIGHT...HAVE INTRODUCED A SLIGHT CHANCE OF SNOW FOR ROUGHLY THE SOUTHWEST 1/3 OF THE CWA FOR THE DAYTIME HOURS...AND WOULD NOT BE SURPRISED TO SEE THIS SLIGHT CHANCE OF SNOW OR AT LEAST FLURRIES EXPANDED TO COVER MORE OF OUR AREA IN LATER FORECASTS IF TRENDS FROM THE 00Z ECMWF/GEM CONTINUE. IN SHORT...THIS LOOKS LIKE A FAVORABLE SETUP FOR A QUICK-HITTING MINOR SNOW ACCUMULATION...AS THE AFOREMENTIONED NORTHWEST-FLOW SHORTWAVE TROUGH THAT DROPS INTO THE DAKOTAS WED NIGHT CONTINUES TO SINK SOUTHEAST ACROSS EASTERN NEB/IA ON THURSDAY...AND A NORTH- SOUTH ORIENTED UPPER JET STREAK APPROACHES OUR LOCAL AREA FROM THE NORTHWEST...HELPING FOCUS A BAND OF MID LEVEL LIFT/SATURATION. NOT LOOKING LIKE HIGH-IMPACT BY ANY MEANS...BUT SOMETHING TO KEEP AN EYE ON. BY THURSDAY NIGHT...FORCING FOR ANY NUISANCE SNOW SHOULD HAVE MOVED OFF TO THE SOUTHEAST. IN THE LOW LEVELS...THE SECOND AND STRONGER COLD FRONT OF THE WEEK ENTERS THE CWA DURING THE DAY...ALTHOUGH THE CORE OF THE TRULY COLD AIR SHOULD REMAIN AT LEAST A FEW HUNDRED MILES TO OUR NORTHEAST...MUCH AS SEEN WITHIN THE PAST WEEK. CERTAINLY THIS WILL RESULT IN A SHARP AND HARD-TO- PIN-DOWN SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT FOR HIGHS ON THURSDAY...AND HAVE SHAVED A COUPLE DEGREES OFF PREVIOUS FORECAST ALL AREAS...AIMING FOR A RANGE FROM NEAR 20 FAR NORTHEAST...MID- UPPER 20S TRI-CITIES AND MID 30S SOUTHWEST. MUCH COLDER AIR WILL NOT BE FAR AWAY...WITH SINGLE DIGIT HIGHS POSSIBLY AS CLOSE AS FAR NORTHEAST NEB...SO WOULD NOT BE SURPRISED TO SEE THIS COLDER AIR PUSH SOUTHWEST INTO OUR AREA A BIT MORE AGGRESSIVELY THAN CURRENTLY ADVERTISED. FRIDAY/FRIDAY NIGHT...THE REGION REMAINS IN WEST-NORTHWEST FLOW ALOFT...AS A COUPLE SHORTWAVE TROUGHS PASS THROUGH THE FLOW...ONE STAYING WELL NORTH FROM CANADA INTO THE NORTHERN GREAT LAKES...AND THE OTHER SLIDING INTO OR JUST SOUTHWEST OF THE AREA. AT THIS TIME...NOTHING APPEARS STRONG ENOUGH TO GENERATE PRECIP FOR OUR CWA. THE BIGGER STORY IS A POTENTIALLY DECENT WARM-UP OVER THURSDAY...AS THE COLD LOW LEVEL RIDGE AXIS SLIDES EAST AND ALLOWS WARMER AIR TO INVADE THE CENTRAL PLAINS ON WESTERLY OR SOUTHERLY BREEZES. HAVE RAISED FRIDAY HIGHS 3-4 DEGREES FROM PREVIOUS FORECAST PER MULTI-MODEL ALLBLEND...NOW RANGING FROM MID 30S NORTHEAST TO LOW-MID 40S SOUTHWEST. SATURDAY CURRENTLY HAS RATHER HIGH CONFIDENCE OF BEING PRECIP-FREE...AND IS ALSO LOOKING LIKE THE WARMEST DAY SINCE MONDAY...AND MADE ALMOST NO CHANGE TO PREVIOUS HIGHS RANGING FROM MID 40S NORTHEAST TO UPPER 40S/LOW 50S SOUTH AND WEST. THE ECWMF SUGGESTS THERE COULD BE A DECENT NORTHWEST BREEZE AS THE REGION IS GLANCED BY A THE EDGES OF A WEAK COLD FRONT DRIVEN BY ANOTHER GREAT LAKES SHORTWAVE TROUGH...BUT EVEN SO DECENT MIXING AND A DOWNSLOPE WIND COMPONENT WOULD HELP AID A WARM-UP. && .PREV DISCUSSION... /ISSUED 1003 PM CST SAT JAN 26 2013/ AVIATION...06Z KGRI TAF...DETERIORATING CONDITIONS ARE EXPECTED AT THE TERMINAL THROUGH THE OVERNIGHT HOURS AS AN UPPER LEVEL DISTURBANCE OUT OF THE DESERT SOUTHWEST EJECTS INTO THE PLAINS. AS A RESULT...MVFR CEILING ARE EXPECTED TO DEVELOP AT THE TERMINAL OVER THE NEXT OR TWO...WITH CEILINGS CONTINUING TO LOWER AND LIGHT RAIN ALONG WITH MVFR VSBYS ARE EXPECTED TO REACH THE TERMINAL AROUND 08Z-09Z. WHILE THE RAINFALL IS EXPECTED TO STOP DURING THE EARLY MORNING HOURS...LOW LEVEL STRATUS AND IFR CIGS ARE EXPECTED TO PERSIST THROUGH MID AFTERNOON...BEFORE WINDS SHIFT AND BECOME SOUTHWESTERLY AROUND 27/18Z. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...WESELY LONG TERM...PFANNKUCH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
645 AM EST SUN JAN 27 2013 .SYNOPSIS... COLD AND DRY HIGH PRESSURE WILL HOLD OVER THE AREA TODAY. AN UPPER LEVEL DISTURBANCE WILL PASS NORTHEASTWARD THROUGH THE REGION TONIGHT THROUGH MONDAY MORNING. THE SURFACE HIGH WILL MOVE OFF THE COAST LATE MONDAY...FOLLOWED BY A WARM SOUTHWEST FLOW INTO THE REGION THROUGH MIDWEEK. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 310 AM SUNDAY... THROUGH SUNRISE...THE MAIN CONCERN ARE THE PATCHES OF DENSE FOG THAT HAVE DEVELOPED ACROSS PORTIONS OF OUR CWA INCLUDING THE TRIANGLE REGION. WE SUSPECT THAT LINGERING GROUND MOISTURE AND PATCHES OF ICE COVER FROM FRIDAYS STORM HAVE HELPED INITIATE THE DENSER PATCHES OF FOG. NOTED THAT THE HRRR CAPTURED THIS FOG PRETTY WELL...AND SHOWS IT CONTINUING THROUGH AROUND 12Z OR SO. GIVEN THE LIMITED NATURE OF THE 1/4 MILE VSBY REPORTS...FOR NOW WE HAVE THIS COVERED WITH AN SPS AND WILL MONITOR AS THE MORNING PROGRESSES. FOR THE DAYTIME TODAY AFTER FOG BURNS OFF...EXPECT LOW-IMPACT WEATHER AS THE S/W RIDGE CURRENTLY OVER THE MS VALLEY DRIFTS EAST TOWARD US AND THE SFC RIDGE REMAINS OVER THE CAROLINAS. DESPITE FORECAST SOUNDINGS DEPICTING A COOLER BL TODAY COMPARED TO YESTERDAY`S OBSERVED SOUNDING...EXPECT MORE SUNSHINE THAN YESTERDAY WHICH SHOULD HELP TEMPS CLIMB A FEW DEGREES HIGHER THAN YESTERDAY... RESULTING IN HIGHS AROUND 40 NORTH TO 46 SOUTH. FOR TONIGHT..THE MAIN CONCERN IS EVOLVING PRECIP POTENTIAL. THE MIDLEVEL RIDGE AXIS IS PROGGED TO SET UP OVER THE SOUTHEAST AND WILL INITIATE WAA ACROSS OUR AREA THAT WILL TAKE PLACE ABOVE THE SHALLOW COOLER NEAR-SFC LAYER. MODELS ARE GENERALLY DEPICTING THE MORE SIGNIFICANT SYNOP SCALE LIFT AND MOISTURE TRANSPORT OCCURRING TO OUR NORTH CLOSER TO A S/W TROUGH THAT WILL BE MOVING ACROSS THE MIDWEST REGION. THE GFS IS THE MOST GENEROUS REGARDING QPF ACROSS OUR AREA OVERNIGHT...WHILE OTHER MODELS KEEP MOST IF NOT ALL OF THE QPF NORTH OF THE VA/NC STATE LINE. IF LIGHT PRECIP DOES MATERIALIZE ACROSS OUR CWA LATER TONIGHT...STILL THINK WE HAVE A DECENT CHANCE TO SEE SOME LIGHT AND BRIEF FROZEN/FREEZING PRECIP AT THE ONSET GIVEN WET BULB COOLING AND LINGERING COLD NEAR-SFC TEMPS. FORECAST SOUNDINGS FOR THE OVERNIGHT PERIOD DEPICT THE AFOREMENTIONED GRADUAL WAA AND MOISTURE INCREASE FROM THE MID-LEVELS DOWN...YET THERE REMAINS PLENTY OF DRY AIR BETWEEN 750-900 MB WHICH RESULTS IN WET BULB TEMPS BELOW FREEZING FOR A SIGNIF LAYER BELOW 850MB. IF LIFT WAS STRONGER AND PRECIP RATES HEAVIER...I WOULDN`T BE SURPRISED IF WE EVEN SAW A QUICK P-TYPE TRANSITION FROM S TO IP TO FZRA THEN RAIN WHILE THE COLUMN SATURATES AND WARMS. FOR NOW WILL KEEP LOW-END POPS ACROSS OUR NORTHERN ZONES CLOSER TO THE TRIAD AND VA BORDER BEGINNING AFT 3 AM. WHILE THE PRECIP RISK STILL LOOKS LOW...IF IT INDEED EVOLVES...THERE WILL BE A CHANCE FOR A FEW LOCALIZED SLICK SPOTS MONDAY MORNING AT THE ONSET...WHICH WOULD MAINLY IMPACT ELEVATED SURFACES AND BRIDGES...BEFORE TEMPS RISE ABOVE FREEZING AFT SUNRISE. WHILE CONFIDENCE IN PRECIP OCCURRING IS TOO LOW ATTM TO WARRANT ANY SORT OF ADVISORIES...WILL CONTINUE TO MENTION IN THE HWO THE POTENTIAL FOR LIGHT FZRA IF PRECIP DOES INDEED EVOLVE. EXPECT LOWS FROM AROUND 30 NORTH TO LOWER 30S SOUTH. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...AS OF 310 AM SUNDAY... MONDAY AND MONDAY NIGHT: THE CENTER OF ANOTHER ARCTIC HIGH...1033 MB CENTERED NEAR CLEVELAND AT 07Z/27TH...WILL HAVE MODIFIED AND DRIFTED OFF THE NC COAST BY MONDAY...THOUGH SIGNIFICANT LINGERING IN-SITU COLD AIR DAMMING EFFECTS WILL REMAIN. AFTER THE EARLY MORNING PRECIPITATION REFERENCED ABOVE...THIS IN-SITU WEDGE WILL MAINTAIN A LOW OVERCAST AND EVEN SOME CONTINUED PATCHES OF DRIZZLE...WITH TEMPERATURES WELL BELOW WHAT NWP WOULD SUGGEST. LOCAL THICKNESS/ TEMPERATURE RESEARCH THAT ACCOUNTS FOR CLOUD COVERAGE AND HEIGHT SUGGESTS TEMPERATURES WILL HOLD IN THE 40S OVER THE PIEDMONT...TO 50-55 DEGREES ACROSS THE SOUTHERN TIER. WHILE SOME PARTIAL CLEARING WILL BE POSSIBLE LATE IN THE DAY OVER THE SANDHILLS...THE STRATUS LAYER WILL EXPAND AND LOWER...WITH AREAS OF DENSE FOG POSSIBLE... SHORTLY AFTER NIGHTFALL. HIGHS 45 TO 55...WITH A MINIMAL DIURNAL FALL INTO THE 39 TO 46 DEGREE RANGE OVERNIGHT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 310 AM SUNDAY... A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION FROM A PAIR OF RIDGES ALONG EACH COAST...WITH A HIGHLY AMPLIFIED BUT PROGRESSIVE TROUGH IN BETWEEN. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH THE EASTERN US/CENTRAL NC WED-WED NIGHT. IT WILL TURN MILDER IN ADVANCE OF THE SYSTEM TUE-WED...THOUGH THIS WARMING WILL BE TEMPERED OVER THE PIEDMONT BY CONTINUED IN-SITU WEDGE INFLUENCE AND ASSOCIATED STRATUS MOISTURE TRAPPED BY A STRONG SUBSIDENCE INVERSION ALOFT. HIGHS TUE FROM AROUND 60 DEGREES NW TO AROUND 70 SE...THEN ABOUT A CATEGORY MILDER IN A BREEZY SOUTHWESTERLY LOW LEVEL FLOW...BUT WITH INCREASING DEEP LAYER MOISTURE/MULTI-LAYERED OVC...ON WED. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES NORTH OF HIGHWAY 64 FRI MORNING...GIVEN THE EXPECTED S/W TRACK ACROSS SOUTHERN VA. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. && .AVIATION /12Z SUNDAY THROUGH WEDNESDAY/... AS OF 645 AM SATURDAY... A LARGE AREA OF FOG AND LOW CIGS CONTINUES EAST OF A N-S LINE FROM KTDF-KTTA-KSOP...AND EXTENDING EASTWARD TO THE COASTAL PLAIN. FLT CONDITIONS IN THIS AREA ARE GENERALLY IFR WITH SOME LOCALIZED LIFR CONDITIONS. FORECAST SOUNDINGS SHOW THIS LIFTING AND DISSIPATING BY 15Z. OUTSIDE OF THE FOG/CIGS...VFR CONDITIONS. AFT 15Z EXPECT VFR CONDITIONS THROUGH APPROX 06Z...WITH HIGH CLOUDS MOVING IN THIS AFTERNOON AND LOWERING THROUGH THE EVENING AHEAD OF THE NEXT WEATHER SYSTEM. LATEST NAM/GFS RUNS HAVE COME IN WITH PERHAPS A LITTLE DEEPER MOISTURE OVERNIGHT AS MID LEVEL WAA AND WEAK LIFT SETS UP ACROSS OUR AREA...THUS INCREASING THE CONCERN THAT SOME LIGHT FROZEN/FREEZING PRECIPITATION MAY OCCUR AFT 28/05Z. WHILE AMOUNTS ARE STILL PROGGED TO BE VERY LIGHT...AREAS POTENTIALLY IMPACTED WOULD BE MAINLY ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN AND AFFECTING KINT...KGSO...KRDU...AND TO A LESSER EXTENT KRWI. TEMPS ARE EXPECTED TO RISE ABOVE FREEZING AFT SUNRISE MONDAY MORNING WITH IMPROVING CONDITIONS. THEN EXPECT MVFR OR VFR CONDITIONS THE REST OF THE MONDAY. A BRIEF IMPROVEMENT IN AVIATION CONDITIONS EXPECTED TUESDAY THOUGH IT WILL BECOME BREEZY A WITH SW WIND GUSTING 20-25 MPH IN THE AFTERNOON. A STRONG COLD FRONT WILL APPROACH CENTRAL NC TUESDAY NIGHT AND CROSS THE AREA LATE WEDNESDAY...BRINGING BREEZY CONDITIONS AND SCATTERED SHOWERS WHICH MAY IMPACT FLT CONDITIONS. IMPROVING CONDITIONS EXPECTED THU. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NP NEAR TERM...NP SHORT TERM...MWS LONG TERM...MWS AVIATION...NP
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
924 AM CST SUN JAN 27 2013 .UPDATE... THE WARM FRONT IS NOW LIFTING ACROSS I-20/I-30 CORRIDORS AND SHOULD PUSH ACROSS THE RED RIVER INTO SOUTHERN OKLAHOMA BY MIDDAY. SOUTH AND SOUTHEAST WINDS ALREADY INCREASING TO 10-15 MPH WITH MIXING AND STRONG WAA ALREADY OCCURRING. WE EXPECT LINGERING AND LOCALIZED DENSE FOG ACROSS THE NORTHEAST COUNTIES TO QUICKLY IMPROVE IN THE NEXT 1-2 HRS. THE DENSE FOG ADVISORY HAS BEEN ALLOWED TO EXPIRE AT 9 AM WITH ANY REMAINING DENSE FOG BEING LOCALIZED AND NOT WIDESPREAD. ALOFT...A SHORTWAVE IS RIDING OVERHEAD AT THE MOMENT...BUT A STOUT AND VERY DRY CAPPING INVERSION/ELEVATED MIXED LAYER BETWEEN 900-650MB SHOULD KEEP ANY RAINFALL IN THE FORM OF ISOLATED/LIGHT SPRINKLES THROUGH THIS MORNING. SOME PARTIAL SUNSHINE IS EXPECTED TO ARRIVE FROM WEST TO EAST THROUGH THE AFTERNOON HOURS IN WAKE OF THIS DISTURBANCE AS SUBSIDENCE ENSUES. THE LOW LEVEL WAA AND BREEZY SOUTH WINDS WILL HELP TEMPERATURES WARM INTO THE LOWER 70S MANY AREAS THIS AFTERNOON. 05/ && .AVIATION... TIMING END OF VLIFR CONDITIONS PRESENTS THE MAIN FORECAST CHALLENGE. AS WARM FRONT CONTINUES TO MOVE NORTH...EXPECT SOUTH WINDS TO INCREASE NEAR OR AFTER SUNRISE AND VISIBILITIES SHOULD IMPROVE FIRST. FWS VAD WINDS HAVE SHOWN LITTLE CHANGE SO FAR THIS MORNING...WITH ONLY A SLIGHT VEERING OF THE 1K FT WINDS. LATEST HRRR AND RAP MODELS FORECAST METROPLEX SFC WINDS TO INCREASE NEAR 13Z/14Z TIME FRAME...AND ALSO SHOW CEILINGS IMPROVING TO IFR NEAR 15Z SO TAFS REFLECT THAT TREND. INCREASING VISIBILITIES IN THE SOUTH ADDS SOME CONFIDENCE TO THIS FORECAST. TONIGHT...SFC WIND SHOULD STAY ABOVE 10 KT...AND VISIBILITIES SHOULD REMAIN HIGHER THAN THIS MORNING EVEN THOUGH CEILINGS WILL DROP TO MVFR AND POSSIBLY IFR. WACO VISIBILITY HAS ALREADY IMPROVED AS DEW POINTS HAVE CLIMBED INTO THE MID 50S...BUT CEILINGS WILL REMAIN LOW UNTIL AFTER SUNRISE AS WELL. && .PREV DISCUSSION... /ISSUED 308 AM CST SUN JAN 27 2013/ AREAS OF FOG WILL CONTINUE ACROSS NEARLY ALL OF NORTH TEXAS THROUGH SUNRISE AS WARM/MOIST AIR MOVES OVER RELATIVELY COOL GROUND. THE FOG WILL BE DENSE AT TIMES SO WE WILL KEEP A DENSE FOG ADVISORY IN PLACE FOR ALL BUT THE EXTREME SOUTHERN COUNTIES. EXPECT VISIBILITIES TO SLOWLY IMPROVE AFTER SUNRISE AND ALL SITES SHOULD BE ABOVE 1/4 MILE VISIBILITY BY 9 AM. A MOSTLY CLOUDY...WARM AND HUMID DAY IS IN STORE FOR NORTH TEXAS AS LOW LEVEL WARM AIR ADVECTION INCREASES IN RESPONSE TO A DEEPENING HIGH PLAINS SURFACE TROUGH. A FEW SPRINKLES OR VERY LIGHT SHOWERS ARE ALSO POSSIBLE TODAY BUT MEASURABLE RAINFALL IS UNLIKELY. LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE REGION TONIGHT AND RESULT IN A WARM NIGHT WITH AREAS OF FOG. THE FOG SHOULD NOT BE AS DENSE TONIGHT/MONDAY MORNING SINCE SOUTHERLY WINDS WILL BE IN THE 10 TO 15 MPH RANGE. MONDAY WILL BE MOSTLY CLOUDY...WARM AND HUMID AS LOW LEVEL WARM AIR ADVECTION CONTINUES AHEAD OF AN APPROACHING UPPER LEVEL TROUGH. AFTERNOONS HIGHS WILL BE IN THE MID 70S TO AROUND 80. LARGE SCALE LIFT ASSOCIATED WITH THE APPROACHING UPPER TROUGH WILL NOT INCREASE UNTIL MONDAY NIGHT. SOME WARM AIR ADVECTION SHOWERS WILL BE POSSIBLE MONDAY NIGHT...BUT THE BEST RAIN AND THUNDERSTORM CHANCES WILL NOT BEGIN UNTIL TUESDAY. IT APPEARS THAT THUNDERSTORMS WILL DEVELOP ALONG AND AHEAD OF A DRY LINE TUESDAY WITH SOME STRONG TO SEVERE STORMS POSSIBLE DUE TO AMPLE SHEAR/ MODERATE INSTABILITY AND FORCING. STORMS SHOULD BE LINEAR IN NATURE AND SHOULD END QUICKLY FROM WEST TO EAST TUESDAY AFTERNOON/EVENING. CONFIDENCE CONTINUES TO INCREASE REGARDING THE MOVEMENT OF THE UPPER TROUGH/DRY LINE AND ALL MODELS EXCEPT THE NAM ARE IN VERY GOOD AGREEMENT. THEREFORE...CHANCE TO LIKELY POPS ARE WARRANTED AT THIS TIME. THE UPPER TROUGH AXIS IS PROGGED TO MOVE EAST OF THE REGION BY WEDNESDAY MORNING WITH DRY NORTHWEST TO WEST FLOW EXPECTED THE REMAINDER OF THE WEEK THROUGH THE WEEKEND. IT WILL BE COOLER AND DRIER WEDNESDAY THROUGH SATURDAY WITH HIGHS MAINLY IN THE 50S AND 60S AND LOWS GENERALLY IN THE 30S AND 40S. 79 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 73 61 75 63 76 / 10 10 10 20 50 WACO, TX 74 63 76 63 76 / 10 10 10 20 50 PARIS, TX 69 61 75 60 76 / 10 10 10 20 60 DENTON, TX 72 61 75 61 75 / 10 10 10 20 50 MCKINNEY, TX 71 64 74 62 76 / 10 10 10 20 50 DALLAS, TX 73 64 76 63 76 / 10 10 10 20 50 TERRELL, TX 73 64 75 63 75 / 10 10 10 20 60 CORSICANA, TX 74 63 77 62 75 / 10 10 10 20 50 TEMPLE, TX 74 62 76 63 76 / 10 10 10 20 40 MINERAL WELLS, TX 74 57 76 60 72 / 10 10 10 20 40 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 84/05
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
434 AM CST SUN JAN 27 2013 .AVIATION... TIMING END OF VLIFR CONDITIONS PRESENTS THE MAIN FORECAST CHALLENGE. AS WARM FRONT CONTINUES TO MOVE NORTH...EXPECT SOUTH WINDS TO INCREASE NEAR OR AFTER SUNRISE AND VISIBILITIES SHOULD IMPROVE FIRST. FWS VAD WINDS HAVE SHOWN LITTLE CHANGE SO FAR THIS MORNING...WITH ONLY A SLIGHT VEERING OF THE 1K FT WINDS. LATEST HRRR AND RAP MODELS FORECAST METROPLEX SFC WINDS TO INCREASE NEAR 13Z/14Z TIME FRAME...AND ALSO SHOW CEILINGS IMPROVING TO IFR NEAR 15Z SO TAFS REFLECT THAT TREND. INCREASING VISIBILITIES IN THE SOUTH ADDS SOME CONFIDENCE TO THIS FORECAST. TONIGHT...SFC WIND SHOULD STAY ABOVE 10 KT...AND VISIBILITIES SHOULD REMAIN HIGHER THAN THIS MORNING EVEN THOUGH CEILINGS WILL DROP TO MVFR AND POSSIBLY IFR. WACO VISIBILITY HAS ALREADY IMPROVED AS DEW POINTS HAVE CLIMBED INTO THE MID 50S...BUT CEILINGS WILL REMAIN LOW UNTIL AFTER SUNRISE AS WELL. && .PREV DISCUSSION... /ISSUED 308 AM CST SUN JAN 27 2013/ AREAS OF FOG WILL CONTINUE ACROSS NEARLY ALL OF NORTH TEXAS THROUGH SUNRISE AS WARM/MOIST AIR MOVES OVER RELATIVELY COOL GROUND. THE FOG WILL BE DENSE AT TIMES SO WE WILL KEEP A DENSE FOG ADVISORY IN PLACE FOR ALL BUT THE EXTREME SOUTHERN COUNTIES. EXPECT VISIBILITIES TO SLOWLY IMPROVE AFTER SUNRISE AND ALL SITES SHOULD BE ABOVE 1/4 MILE VISIBILITY BY 9 AM. A MOSTLY CLOUDY...WARM AND HUMID DAY IS IN STORE FOR NORTH TEXAS AS LOW LEVEL WARM AIR ADVECTION INCREASES IN RESPONSE TO A DEEPENING HIGH PLAINS SURFACE TROUGH. A FEW SPRINKLES OR VERY LIGHT SHOWERS ARE ALSO POSSIBLE TODAY BUT MEASURABLE RAINFALL IS UNLIKELY. LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE REGION TONIGHT AND RESULT IN A WARM NIGHT WITH AREAS OF FOG. THE FOG SHOULD NOT BE AS DENSE TONIGHT/MONDAY MORNING SINCE SOUTHERLY WINDS WILL BE IN THE 10 TO 15 MPH RANGE. MONDAY WILL BE MOSTLY CLOUDY...WARM AND HUMID AS LOW LEVEL WARM AIR ADVECTION CONTINUES AHEAD OF AN APPROACHING UPPER LEVEL TROUGH. AFTERNOONS HIGHS WILL BE IN THE MID 70S TO AROUND 80. LARGE SCALE LIFT ASSOCIATED WITH THE APPROACHING UPPER TROUGH WILL NOT INCREASE UNTIL MONDAY NIGHT. SOME WARM AIR ADVECTION SHOWERS WILL BE POSSIBLE MONDAY NIGHT...BUT THE BEST RAIN AND THUNDERSTORM CHANCES WILL NOT BEGIN UNTIL TUESDAY. IT APPEARS THAT THUNDERSTORMS WILL DEVELOP ALONG AND AHEAD OF A DRY LINE TUESDAY WITH SOME STRONG TO SEVERE STORMS POSSIBLE DUE TO AMPLE SHEAR/ MODERATE INSTABILITY AND FORCING. STORMS SHOULD BE LINEAR IN NATURE AND SHOULD END QUICKLY FROM WEST TO EAST TUESDAY AFTERNOON/EVENING. CONFIDENCE CONTINUES TO INCREASE REGARDING THE MOVEMENT OF THE UPPER TROUGH/DRY LINE AND ALL MODELS EXCEPT THE NAM ARE IN VERY GOOD AGREEMENT. THEREFORE...CHANCE TO LIKELY POPS ARE WARRANTED AT THIS TIME. THE UPPER TROUGH AXIS IS PROGGED TO MOVE EAST OF THE REGION BY WEDNESDAY MORNING WITH DRY NORTHWEST TO WEST FLOW EXPECTED THE REMAINDER OF THE WEEK THROUGH THE WEEKEND. IT WILL BE COOLER AND DRIER WEDNESDAY THROUGH SATURDAY WITH HIGHS MAINLY IN THE 50S AND 60S AND LOWS GENERALLY IN THE 30S AND 40S. 79 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 73 61 75 63 76 / 10 10 10 20 50 WACO, TX 72 63 76 63 76 / 10 10 10 20 50 PARIS, TX 68 61 75 60 76 / 10 10 10 20 60 DENTON, TX 72 61 75 61 75 / 10 10 10 20 50 MCKINNEY, TX 71 64 74 62 76 / 10 10 10 20 50 DALLAS, TX 73 64 76 63 76 / 10 10 10 20 50 TERRELL, TX 73 64 75 63 75 / 10 10 10 20 60 CORSICANA, TX 74 63 77 62 75 / 10 10 10 20 50 TEMPLE, TX 74 62 76 63 76 / 10 10 10 20 40 MINERAL WELLS, TX 74 57 76 60 72 / 10 10 10 20 40 && .FWD WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR TXZ091>095- 100>107-115>123-129>135-141>148-156-157-159-161. && $$ /
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
443 AM CST SUN JAN 27 2013 .VERY SHORT TERM...TODAY AND TONIGHT. FORECAST CONFIDENCE MEDIUM. FOCUS SQUARELY ON PRECIPITATION TYPE/TIMING WITH POTENT SHORT WAVE APPROACHING FROM THE SOUTHWEST. ENHANCED CLOUDS IN PACIFIC MOISTURE PLUME AHEAD OF WAVE WRAPPING AROUND MULTIPLE VORTICITY MAXIMA NOTED ON WATER VAPOR LOOPS OVER SW NEBRASKA...EASTERN KANSAS AND EXTREME SE COLORADO...WITH A PRONOUNCED DRY SLOT BEHIND PLUME FROM NRN MEXICO INTO KANSAS. PRECIPITATION MOVES IN LATE THIS MORNING/EARLY AFTERNOON INTO THIS EVENING WITH A BAND OF PRECIPITATION ASSOCIATED WITH STRONG LAYER FRONTOGENETIC RESPONSE TO 850-700MB WARM AIR ADVECTION AHEAD OF THE WAVE. MODEL SOUNDINGS SHOW INITIAL MOISTENING NEEDED TO SATURATE DRY LAYER BELOW 750 MB...WITH EVAPORATIVE COOLING TAKING THE WET BULB TEMP TO 0C IN THE COLUMN FOR A PERIOD OF ALL SNOW TO START...THEN WARMING ALOFT AND LOSS OF ICE CRYSTALS WITH THE DGZ DRYING OUT AS PRONOUNCED DRY SLOT PUSHING NEWD ACROSS KANSAS ON WATER VAPOR LOOPS INTRODUCES LIQUID INTO THE SUB-0C LAYER BELOW 900 MB TO THE SURFACE. THIS BRINGS SLEET AND EVENTUALLY FREEZING RAIN INTO THE MIX...GOING TO ALL LIGHT FREEZING RAIN AND THEN RAIN. CONSENSUS QPF AMOUNTS AND TEMPERATURE TRENDS BRINGS ICE ACCUMULATIONS BETWEEN 0.10 AND 0.20...WITH SNOW AROUND 0.5 SOUTH...WITH 1 TO 1.5 NORTH WITH LATER SWITCH TO A MIX. WHILE THIS WILL BE A WINTRY MESS...AMOUNTS STAY WITHIN ADVISORY GUIDELINES. WILL MONITOR DURING EVENT AS NAM SOUNDINGS WERE SHOWING A MORE PROLONGED PERIOD OF SNOW...WHILE RAP LEANED MORE TOWARDS FZRA TO RAIN WITH VERY LITTLE SNOW. SURFACE TEMPS WARM ENOUGH FOR ALL RAIN BY 06Z MONDAY..EXCEPT FOR AN AREA IN THE FAR NRN CWA SO WILL KEEP START AND END TIMES AS IS FOR ADVISORY. WITH WARMING THROUGH THE DAY AND LITTLE DROP OFF TONIGHT...WENT WITH LATE HIGHS IN THE LOW TO MID 30S..AND LOWS ONLY A FEW DEGREES COOLER. MONDAY - CONFIDENCE...MEDIUM SHORTWAVE AXIS ACROSS THE CWA EARLY ON WITH THIS WAVE WHISKING EAST PRETTY QUICK. BASED ON CONSENSUS OF MODELS WILL LIMIT POPS TO JUST THE MORNING HOURS. BRIEF PERIOD OF SURFACE/850 RIDGING TAKING HOLD. MONDAY NIGHT - CONFIDENCE...MEDIUM STRENGTHENING 40-50 KNOT SW LOW LEVEL JET AIMS AT THE CWA. DECENT MOISTURE ADVECTION NOTED. ECMWF HAS QPF MAX NEAR WI/IL BORDER WHILE GEM HAS IT MORE ACROSS THE CWA. NOT IMPRESSED WITH BUFKIT ELEVATED CAPE OR LAPSE RATES SO WILL HOLD OFF ON THUNDER MENTION FOR NOW. DID NUDGE POPS UP A BIT MORE THOUGH. TUESDAY - CONFIDENCE...MEDIUM MODELS TAKE SURFACE LOW VICINITY OF NE IA/SW WI AND RACE IT NORTHEAST THROUGH THE DAY. THIS WILL DRAG A COLD FRONT ACROSS SRN WI...BUT BEFORE FRONT ARRIVES...PLENTY OF MILD AIR IN PLACE. 925 TEMPS IN THE 10-12C RANGE ON THE ECMWF/GFS...WHILE THE NAM IS MUCH QUICKER TO BRING THE FRONT THROUGH. GOING WITH THE CONSENSUS OF THE ECMWF/GFS WILL HAVE TEMPS INTO THE 50S FOR THE SE CWA. ADDED A CHANCE OF THUNDER IN THE FAR SE DUE TO PREFRONTAL SOUNDINGS REVEALING ELEVATED INSTABILITY. THERMODYNAMICS LOOKING BETTER TO OUR SOUTH AND SOUTHEAST PER TRENDS IN CWASP. SWODY3 GENERAL DOES CLIP OUR SE AS WELL. WEDNESDAY - CONFIDENCE...MEDIUM LOW LEVEL COLD ADVECTION WITH MID LEVEL TROUGH AXIS SWINGING ACROSS. PRESSURE GRADIENT FAIRLY TIGHT AND WITH DECENT MIXING IN LOW LEVELS EXPECT NW WINDS TO BE ON THE GUSTY SIDE. SO A STARK CONTRAST TO THE MILD CONDITIONS OF TUESDAY. ECWMF A BIT SLOWER ON THE COLD ADVECTION...SEEING A 5-7 DEGREE DIFFERENCE WITH 925 TEMPS. DRY SLOT STILL IN PLACE THROUGH MIDDAY THEN A LITTLE MORE MOISTURE EXPECTED. WILL GO WITH THE SLIGHT CHANCE OF SNOW SHOWERS AS DEPICTED BY ALLBLEND POPS. THURSDAY - CONFIDENCE...MEDIUM COLDER YET WITH 925 TEMPS -20 TO -24C WHICH SUGGESTS SINGLE DIGIT HIGH TEMPS FOR MUCH OF THE CWA. ALLBLEND SHOWING 10-15 BUT THAT MAY BE TOO WARM. MIXED IN SOME COLDER NUMBERS FROM THE CONSRAW TO BRING TEMPS DOWN A BIT CLOSER TO THE 925 SCHEME. FRIDAY - CONFIDENCE...MEDIUM ECMWF/GFS AGREE THAT CORE OF COLDEST AIR SHIFTS EAST WITH LOW LEVEL WARM ADVECTION GETTING UNDERWAY AHEAD OF THE NEXT TROUGH. FRIDAY NIGHT AND SATURDAY - CONFIDENCE...MEDIUM COMBO OF WARM ADVECTION AND PASSAGE OF SURFACE/850 TROUGH BRINGS SHSN CHANCES THIS PERIOD. NOT LOOKING LIKE MUCH AT THIS POINT. ECMWF MUCH MORE AGGRESSIVE ON DEGREE OF COLD ADVECTION IN THE WAKE OF THE FRONT SATURDAY AFTERNOON/EVENING. && .AVIATION/12Z TAFS/...VFR CONDITIONS WILL DETERIORATE QUICKLY TO MVFR WITH PCPN MOVING INTO KMSN AROUND 17Z-18Z...KUES 18Z-19Z AND KMKE AND KENW AROUND 20Z...THEN FALLING TO IFR AND HOLDING THROUGH THE REMAINDER OF THE FORECAST. PCPN SHOULD START OUT AS LIGHT SNOW...MIXING WITH SLEET AND THEN FREEZING RAIN...GOING OVER TO ALL RAIN AS TEMPERATURES WARM. PERIOD OF FREEZING RAIN WILL BE SHORTER AT KMKE AND KENW AS TEMPERATURES WILL RISE ABOVE FREEZING SOONER WITH SE WINDS. && .MARINE... EXTENDED SMALL CRAFT ADVISORY UNTIL 12Z MONDAY TO ALLOW WAVES SUFFICIENT TIME TO SUBSIDE AFTER WINDS FALL OFF BELOW CRITERIA LATE THIS EVENING. WINTRY MIX OVERSPREADING THE NEARSHORE THIS AFTERNOON WILL GO OVER TO RAIN WINDS WILL HOVER AROUND SMALL CRAFT CRITERIA FROM TUESDAY NIGHT THROUGH FRIDAY AS THE GRADIENT TIGHTENS BETWEEN ANOTHER LOW PRESSURE AREA CROSSING THE WESTERN GREAT LAKES REGION TUESDAY AND ARCTIC HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT CST TONIGHT FOR WIZ062-063-067>069. WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO MIDNIGHT CST TONIGHT FOR WIZ059-060-064>066-070>072. WINTER WEATHER ADVISORY FROM NOON TODAY TO 3 AM CST MONDAY FOR WIZ046-047-056-057. WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 3 AM CST MONDAY FOR WIZ051-052-058. LM...SMALL CRAFT ADVISORY FROM NOON TODAY TO 4 AM CST MONDAY FOR LMZ643>646. && $$ UPDATED TO ADD MARINE SECTION. TODAY/TONIGHT AND AVIATION/MARINE...REM MONDAY THROUGH SATURDAY...COLLAR
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
145 PM EST SUN JAN 27 2013 .AVIATION... A SURGE OF MILD AND MOIST AIR AHEAD OF AN ADVANCING SYSTEM WILL CAUSE FREEZING RAIN TO DEVELOP EARLY IN THE TAF PERIOD. THE LATEST DOPPLER RADAR DUAL POLARITY IMAGES SUPPORT A MIX OF SLEET IN THE UPSTREAM HEAVIER RETURNS. THE CHANGEOVER FROM FREEZING RAIN TO RAIN REALLY CHALLENGING WITH GROUND SURFACES BELOW FREEZING AND WET BULB TEMPS STILL WELL DOWN IN THE 20S. AT 135 PM...WE OBSERVED A MIX OF SLEET AND FREEZING RAIN HERE AT OUR OFFICE. WITH ALL CONSIDERED...PLANNED TO STAY CONSERVATIVE WITH GENERALLY A SLOWER CHANGEOVER TIME FROM FREEZING RAIN TO SLEET IN THE TAFS. THE 02Z TAF CHANGEOVER TIME AT FWA MAY BE TOO SOON AS ALSO THE 03Z TIME AT SBN. && .PREV DISCUSSION... /ISSUED 429 AM EST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH MONDAY NIGHT FORECAST CONCERN FOR THE SHORT TERM WILL BE THE POTENTIAL OF A PERIOD OF FREEZING RAIN THIS AFTERNOON INTO THIS MAINLY THIS EVENING. ELEVATED ECHOES EVIDENT ON RADAR MOSAIC THIS MORNING FROM NORTH CENTRAL WISCONSIN INTO SOUTHERN LOWER MICHIGAN ASSOCIATED WITH LEADING EDGE OF STRONGER 850-700 HPA THETA ADV. THIS ELEVATED FORCING THIS MORNING WILL ONLY SERVE IN TOP DOWN SATURATION WITH DEEPER MOISTURE AND STRONGER LOW LEVEL THEATE ADVECTION SITUATED BACK ACROSS THE SOUTHERN/CENTRAL PLAINS WHERE RAIN HAS BEEN EXPANDING IN COVERAGE. 06Z RAP LOW LEVEL MOISTURE TRANSPORT PROGS DEPICTING STRONGEST 925 HPA TRANSPORT VECTORS INTO MISSOURI/SOUTHERN IOWA THIS AFTERNOON WITH ADVECTION SOMEWHAT DELAYED ACROSS LOCAL AREA DUE TO WEAK LOW LEVEL SOUTHEAST WIND COMPONENT ASSOCIATED WITH DEPARTING LOW LEVEL ANTICYCLONE. IT STILL APPEARS CHANCES OF PRECIP WILL INCREASE ACROSS WESTERN PORTIONS OF THE FORECAST AREA TOWARD THE 21Z TIMEFRAME BUT PRECIPITATION SHOULD BE INITIALLY VERY LIGHT. CANNOT COMPLETELY DISCOUNT A VERY BRIEF PERIOD OF A SNOW/SLEET MIX DUE TO WET BULB EFFECTS...BUT STRENGTH OF LOW LEVEL WARM/MOIST ADVECTION VIA AN APPROACHING 60 KNOT LOW LEVEL JET AXIS SHOULD SUPPORT PRECIP TYPE OF MAINLY SLEET/FREEZING RAIN MIX BY THE TIME MORE APPRECIABLE PRECIP RATES WOULD BE OBSERVED LATE THIS AFTERNOON AS LOW LEVELS SATURATE. STRENGTH OF LOW LEVEL MOISTURE ADVECTION AND INSPECTION OF RAP/NAM FORECAST SOUNDINGS EVEN OFFERS SOME QUESTION AS TO THE POSSIBILITY THAT ONCE LOW LEVEL SATURATION OCCURS...PRECIPITATION TYPE MAY BE MAINLY IN THE FORM OF RAIN ACROSS THE FAR SOUTH/SOUTHWEST. HAVE CONTINUED TO RELY MORE ON NAM IDEA IN TERMS OF INITIAL LOW LEVEL SATURATION/WET BULB PROCESSES WITH GFS OFTEN EXHIBITING A MOIST BIAS IN RAPID LOW LEVEL MOISTENING WITH THIS TYPE OF SETUP. IT STILL APPEARS AS THOUGH MOST LOCATIONS MAY RECEIVE A 2 TO 4 HOUR PERIOD OF MIXED PRECIP AND FREEZING RAIN THREAT BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING STILL APPEARS TO BE ACROSS THE FAR NORTHEAST WHICH IS ALSO SUPPORTED BY SREF PROBABILISTIC PRODUCTS. GIVEN INCREASING CONFIDENCE THAT PRIMARY IMPACTS WOULD BE FROM A PERIOD OF FREEZING RAIN WITH LITTLE IF ANY SLEET ACCUMULATION...WILL REPLACE THE WINTER WEATHER ADVISORY WITH A FREEZING RAIN ADVISORY. LATEST DATA CONTINUES TO SUGGEST THAT DURATION OF FREEZING PRECIP MAY BE SLIGHTLY SHORTER THAN PREVIOUSLY ANTICIPATED...ESPECIALLY ACROSS SOUTHERN HALF OF THE AREA BUT WILL KEEP TIMING OF WSW THE SAME FOR BOTH SEGMENTS AND OPT TO HOLD ONTO SOUTHERN PORTIONS OF THE ADVISORY AT THIS TIME. EVEN AFTER TEMPERATURES WARM ABOVE FREEZING THIS EVENING...RECENT VERY COLD TEMPS AND COLD GROUND CONDITIONS MAY STILL SUPPORT SOME FREEZING ON ROADWAYS FOR A TIME AFTER TEMPS RISE ABOVE FREEZING...ESPECIALLY ACROSS NORTHERN HALF. HAVE MAINTAINED ICE ACCUMULATIONS IN THE 0.05 TO 0.1 INCH RANGE...WITH THE HIGHER END OF THIS RANGE EXPECTED ACROSS FAR NORTH/NORTHEAST. BROAD ISENTROPIC UPGLIDE TO CONTINUE INTO MONDAY WITH ANOTHER LOW AMPLITUDE MID LEVEL WAVE TRACKING ACROSS THE GREAT LAKES REGION. NOT MUCH ORGANIZATION EXPECTED TO PRECIP ON MONDAY BUT WITH BROAD ISENTROPIC UPGLIDE AND WEAK MID LEVEL FORCING WILL CONTINUE TO CARRY HIGH RAIN POPS THROUGH MONDAY/MONDAY NIGHT. NEXT WARM FRONTAL SURGE ASSOCIATED WITH AMPLIFYING UPSTREAM LONGWAVE TROUGH SHOULD RESULT IN INCREASED PRECIP CHANCES MONDAY NIGHT WITH EVEN THE POSSIBILITY OF SOME EMBEDDED THUNDER ACROSS THE WEST LATE IN THE NIGHT. TEMPS SHOULD EXHIBIT NON DIURNAL TENDENCIES MONDAY NIGHT WITH THE WARM FRONT...POSSIBLY EVEN RISING INTO THE LOWER 50S ACROSS THE SOUTH BY MORNING. LONG TERM...TUESDAY THROUGH SATURDAY PROGRESSIVE HIGH AMPLITUDE TROUGH WILL BE FIRMLY IN PLACE ACROSS THE ROCKIES AT THE START OF THE PERIOD TUESDAY WITH A REMARKABLE 150+ KNOT MERIDIONAL UPPER LEVEL JET ON THE DOWNSTREAM SIDE. THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE IS IMPRESSIVE AND SEVERAL WAVES OF LOW PRESSURE ARE EXPECTED TO DEVELOP ALONG IT AS THE TROUGH INCHES ACROSS OUR REGION. BUT FIRST...OUR CWA WILL BE FIRMLY IN SOUTHWEST FLOW ON TUESDAY WITH CONTINUED WARM/MOIST AIR ADVECTION. 850MB DEWPOINTS CLIMB TO AROUND 10C WITH PW VALUES WELL OVER AN INCH BY LATE TUESDAY. SURFACE DEWPOINTS ALSO STILL EXPECTED TO CLIMB INTO THE MID 50S...MAKING FOR A VERY WARM DAY BY JANUARY STANDARDS. IN FACT...LATEST GUIDANCE IS SHOWING HIGHS NEAR OR ABOVE THE RECORDS (58 FOR SBN AND 62 FOR FWA...BOTH SET IN 1914). BUMPED UP HIGHS BUT WILL LEAVE THEM JUST BELOW 60F FOR MOST AREAS GIVEN CONCERNS OVER STILL VERY COLD GROUND TEMPERATURES. PRECIP CHANCES/AMOUNTS DURING THE DAY TUESDAY WILL DEPEND ON TIMING AND EVOLUTION OF LOW LEVEL JET WITH RAGGED ISENTROPIC ASCENT SUPPORTING MAINLY JUST SCATTERED SHOWERS UNTIL THE FRONT ARRIVES. MUCH BETTER FORCING WILL ARRIVE LATE TUESDAY WITH STRONG MIDLEVEL HEIGHT FALLS AND VERY FAVORABLE UPPER LEVEL JET DYNAMICS. THIS WILL FAVOR SURFACE CYCLOGENESIS SOMEWHERE OVER THE GREAT LAKES REGION WITH COPIOUS AMOUNTS OF RAINFALL ALONG THE TRAILING COLD FRONT. LATEST NAM BUFR SOUNDINGS ARE ALSO MUCH MORE OMINOUS REGARDING THUNDER POTENTIAL WITH ALMOST 1000 J/KG OF ELEVATED CAPE. THIS IS PROBABLY OVERDONE BUT GIVEN THE STRENGTH OF THE DEVELOPING LLJ COULD EASILY SEE SOME THUNDER OCCURRING LATE TUESDAY AND WILL ADD MENTION TO THE FORECAST. GIVEN THE POTENTIAL FOR CONVECTION COUPLED WITH STRONG WARM/MOIST AIR ADVECTION AHEAD OF THE FRONT AND EXCELLENT FORCING ALOFT...QPF AMOUNTS IN EXCESS OF AN INCH ARE POSSIBLE TUESDAY NIGHT. THIS CERTAINLY RAISES THE CONCERN FOR FLOODING WITH MELTING SNOWPACK IN THE NORTH AND LIKELY STILL FROZEN GROUND. ARCTIC AIR RETURNS BY LATE WEDNESDAY WITH THE REESTABLISHMENT OF NORTHWEST FLOW AND CAA. COLDEST AIR WILL TAKE SOME TIME TO FILTER INTO THE REGION SO THERE MAY BE A BRIEF LULL IN THE PRECIP BEFORE THE LAKE EFFECT GETS GOING BUT WILL MAINTAIN HIGH CHANCE POPS ON WEDNESDAY GIVEN UNCERTAINTY IN EXACT TIMING OF EXITING FRONT. WILL ALSO LIKELY BE AN ATYPICAL DIURNAL CURVE WITH AFTERNOON TEMPS FALLING FROM MORNING HIGHS AROUND 40F. LAKE RESPONSE DOESNT TRULY LIGHT UP UNTIL THURSDAY WITH THE APPROACH OF A VIGOROUS SHORTWAVE AND 850MB TEMPS BOTTOMING OUT IN THE LOW -20S. LAKE EFFECT SNOW WILL CONTINUE THROUGH FRIDAY BUT A WNW FETCH WILL LIKELY CONFINE BIGGEST IMPACTS TO OUR EXTREME NORTHERN COUNTIES. HIGH TEMPS DURING THIS PERIOD WILL LIKELY STRUGGLE TO GET ABOVE 20F GIVEN AFOREMENTIONED 850MB TEMPS. LOW LEVEL RIDGE AXIS SHIFTS EAST ON FRIDAY BUT ONLY A BRIEF RESPITE FROM PRECIP CHANCES BEFORE ANOTHER CLIPPER SYSTEM DIVES ACROSS THE REGION ON SATURDAY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH FROM MONDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR INZ003>009-012>018-020-022>027-032>034. FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR INZ006-007-009. FREEZING RAIN ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR INZ003>005-008-012>018-020-022>027-032>034. MI...FLOOD WATCH FROM MONDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR MIZ077>081. FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR MIZ078>081. FREEZING RAIN ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ077. OH...FLOOD WATCH FROM MONDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR OHZ001-002-004-005-015-016-024-025. FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 3 AM EST MONDAY FOR OHZ001-002-004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...MARSILI LONG TERM...AGD AVIATION...SKIPPER
AREA FORECAST DISCUSSION
NWS DES MOINES IA
335 PM CST SUN JAN 27 2013 .SHORT TERM /TONIGHT/... UPPER LEVEL FORCING CONTINUES TO WANE WITH DEPARTING KINEMATIC AND THERMODYNAMIC FORCING AS SHORT WAVE CROSSES SRN MN/WI BORDER. POCKET OF WEAK INSTABILITY WITH A FEW HUNDRED MUCAPES IS ALSO EXITING INTO IL. THIS HAD ENDED OUR THREAT OF SHOWERS AND SUBSTANTIAL PRECIP. HOWEVER WEAK FORCING AND CERTAINLY MOISTURE LINGERS 2KM AND BELOW AND WILL RESULT IN PERSISTENT DRIZZLE OR FREEZING DRIZZLE. THIS SENSIBLE WEATHER IS DEPICTED NICELY BY THE LOW LEVEL RAP 285-295K ISENT LAYER WHICH SHOWS MODERATE MOISTURE TRANSPORT AND LIFT THROUGH THE EVENING. THIS WILL ALSO KEEP LOW CLOUDS AND FOG LOCKED IN PLACE. FOG MAY BE DENSE AT TIMES...BUT CONFIDENCE IN WIDESPREAD 1/4SM OR LESS VSBYS IS NOT GREAT ENOUGH TO HEADLINE QUITE YET WITH MOISTURE TRANSPORT ENDING LATE AND LITTLE RADIATIONAL COOLING. ALTHOUGH ONLY TOKEN ADDITIONAL ICE ACCUMULATIONS ARE ANTICIPATED...HAVE LEFT HEADLINES UNCHANGED NORTH. LITTLE IMPROVEMENT IS ANTICIPATED THERE WITH TEMPS HOVERING AROUND 32F ALONG WITH THE DRIZZLE AND FOG. ADVISORY CANCELED FARTHER SOUTH WHERE TEMPS SHOULD REMAIN ABOVE FREEZING. .LONG TERM /MONDAY THROUGH SUNDAY/... FAIRLY ACTIVE MID/LONG RANGE ACROSS THE AREA WITH MAJOR FOCUS ON MONDAY INTO TUESDAY. LARGE UPPER LEVEL TROUGH THAT HAS BEEN SLOWLY PROGRESSING THROUGH THE INTERMOUNTAIN WEST...WILL CONTINUE TO TRANSLATE EASTWARD ACROSS THE CENTRAL PLAINS INTO THE OHIO VALLEY THROUGH WEDNESDAY. INITIALLY THE STATE WILL REMAIN IN SOUTHWEST FLOW ALOFT...WITH CONTINUE LOW LEVEL MOISTURE PUMPING NORTHWARD FROM THE GULF OF MEXICO. SFC LOW PRESSURE DEVELOPING IN LEE OF THE ROCKIES...BEGINS TO SHIFT EAST AND ELONGATE INTO CENTRAL KS/SC NEBRASKA TOWARD MONDAY AFTERNOON. AN ASSOCIATED WARM FRONT WILL LIFT NORTHWARD THROUGH THE STATE LATE MONDAY INTO MONDAY NIGHT. MOISTURE OVERRUNNING THE AREA TO THE NORTH OF THIS WARM FRONT WILL LEAD TO LOW STRATUS AND FOG LINGERING ACROSS THE CWA MONDAY. ISENTROPIC LIFT EVIDENT ON THE 285K TO 290K SURFACES BEGINS TO SHOW UP ACROSS THE SOUTHERN CWA BY LATE MONDAY MORNING WITH LIFT SPREADING NORTHWARD INTO THE AFTERNOON HOURS. THIS WILL BRING THE CHANCE FOR DRIZZLE OR LIGHT RAIN TO MUCH OF THE SOUTHERN HALF OF IOWA BY MONDAY AFTERNOON IN ADDITION TO THE LOW CLOUDS/FOG. VISIBILITIES EXPECTED TO BE QUITE LOW WITH THE FOG THROUGHOUT THE MORNING HOURS...WITH SOME IMPROVEMENT IN THE AFTERNOON. POSSIBILITY OF NEEDING A DENSE FOG ADVISORY FOR THE MORNING HOURS...BUT WILL NOT ISSUE NOW DUE TO WINTER HEADLINES ALREADY IN EFFECT FOR SIMPLICITY. GREATER PUSH OF MOISTURE...WITH DEEPER SATURATION EXPECTED AND CONTINUE WAA INTO MONDAY NIGHT AS WARM FRONT LIFTS NORTHWARD THROUGH THE STATE. HAVE A NON-DIURNAL TEMPERATURE TREND MONDAY NIGHT AS AREAS EXPECTED TO WARM OR REMAIN STEADY BEHIND THE WARM FRONT. FOG COULD CONTINUE TO BE AN ISSUE INTO MONDAY NIGHT WITH ABUNDANT LOW LEVEL MOISTURE. ADDITIONALLY NAM/GFS BOTH ADVERTISE SOME ELEVATED INSTABILITY SPREADING NORTHWARD INTO THE CWA...WITH THE NAM MOST AGGRESSIVE. THEREFORE CONTINUED THE THUNDER MENTION ACROSS THE SOUTHERN HALF/EASTERN HALF OF THE CWA. AS THE SFC LOW LIFTS NORTHEASTWARD THROUGH THE STATE INTO TUESDAY MORNING...ASSOCIATED COLD FRONT TO PUSH THROUGH CWA TUESDAY. THIS WILL LEAD TO PRECIPITATION TRANSITIONING TO A MIX OF RAIN/SNOW TO ALL SNOW/FLURRIES ACROSS THE NORTHERN CWA BEFORE PRECIPITATION TAPERS OFF LATER THAT DAY. POSSIBILITY STILL EXISTS THAT COULD SEE A MIX OF FREEZING RAIN AS WELL...AS DEPENDS ON HOW DEEP SATURATION IS AND IF ICE CAN BE INTRODUCED INTO THE COLUMN. CURRENT NAM SOUNDINGS SUGGEST DEEP ENOUGH SATURATION WITH ICE INTRODUCED WHICH WOULD ALLOW FOR SNOW...WHILE GFS SUGGEST DRIER AIR ALOFT WITH NO ICE INTRODUCTION LEADING TO RAIN/FZRA/FZDZ DEPENDING ON SURFACE TEMPS. FOR NOW HAVE TRENDED FORECAST TOWARD THE NAM SOLUTION. BROAD UPPER LEVEL TROUGH THEN REMAINS ACROSS THE EASTERN US...WITH NORTHWESTERLY FLOW ALOFT FOR THE REMAINDER OF THE PERIOD. THIS WILL ALLOW FOR A SERIES OF WEAK SHORTWAVES TO TRAVEL THROUGH THE MAIN UPPER LEVEL TROUGH AND DROP SOUTH THROUGH THE CWA. THIS WILL BRING CONTINUED PUSHES OF ARCTIC AIR FOR LATE THIS WEEK INTO THE WEEKEND...WITH H85 TEMPS DROPPING INTO THE NEGATIVE TEENS TO 20S CELSIUS. THIS WILL SEND TEMPERATURES TO BELOW AVERAGE BY THE END OF THE WEEK INTO THE WEEKEND. WITH EACH WAVE PASSAGE...SOME FLURRIES OR LIGHT SNOW MAY BE POSSIBLE BUT HAVE LEFT THE FORECAST MAINLY DRY FOR NOW WITH THE UNCERTAINTY IN THE TIMING OF EACH IMPULSE. BROAD UPPER LEVEL RIDGING BEGINS TO NUDGE INTO THE CENTRAL US TOWARD THE END OF THE WEEKEND INTO EARLY NEXT WEEK...SUGGESTING A WARMING TREND AS H85 TEMPS CLIMB BACK ABOVE FREEZING. && .AVIATION...27/18Z CONDITIONS HAVE CONTINUED TO DETERIORATE INTO IA NORTH OF WARM FRONT EXTENDING ACROSS NE AND KS INTO MO AT 17Z. WIDESPREAD LIFR/IFR CONDITIONS ARE IN PLACE OVER IA AND ARE EXPECTED TO REMAIN THAT WAY INTO THE NIGHT WITH PERSISTENT DRIZZLE AND/OR FREEZING DRIZZLE THROUGH AT LEAST THE EVENING. LITTLE IMPROVEMENT IS EXPECTED MON MORNING EITHER WITH LIGHT WINDS KEEPING LOW LEVEL MOISTURE IN PLACE. KFOD WIND SENSOR HAS FROZEN WITH FORECAST ESTIMATED. && .DMX WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR EMMET- HAMILTON-HUMBOLDT-KOSSUTH-MARSHALL-PALO ALTO-POCAHONTAS- STORY-TAMA-WEBSTER. WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR BLACK HAWK- BREMER-BUTLER-CERRO GORDO-FRANKLIN-GRUNDY-HANCOCK-HARDIN- WINNEBAGO-WORTH-WRIGHT. && $$ SHORT TERM...SMALL LONG TERM...BEERENDS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1126 AM CST SUN JAN 27 2013 .AVIATION... CONDITIONS WILL BE...OR SHORTLY BECOME IFR/LIFR BY 20Z...THEN CONTINUE FOR AT LEAST THE NEXT 24 HOURS WITH PERIODS OF -FZRA BECOMING -RA OR -DZ AS TEMPERATURE RISE ABOVE FREEZING BETWEEN 18-23Z. WARM MOIST AIR MOVING UP FROM THE SOUTH WILL KEEP CEILINGS LOW...AOB 1K AGL AND PROBABLY BELOW 500 FT THIS EVENING AND MONDAY. VISIBILITIES WILL BE 1-2 MILES THIS AFTERNOON...DECREASING TO MOSTLY AOB 1 MILE TONIGHT THROUGH MONDAY WITH AIRPORT MINIMUM THRESHOLDS POSSIBLE LATE TONIGHT AND MOST OF THE MORNING HOURS ON MONDAY. NICHOLS && .PREV DISCUSSION... /ISSUED 400 AM CST SUN JAN 27 2013/ UPDATE... RADAR TRENDS INDICATE SLEET/FREEZING RAIN HAS MOVED INTO OR WILL DEVELOP VERY SOON IN THE FAR SOUTHWEST PARTS OF THE CWFA. RECENT RAP TRENDS CONTINUE TO SHOW A VERY RAPID TOP DOWN SATURATION OCCURRING THIS MORNING WITH WBZ TEMPERATURES AT THE SFC REMAINING BELOW FREEZING. TEMPERATURES WILL BE THE KEY AND THE DRY ATMOSPHERE SHOULD INITIALLY ALLOW TEMPERATURES TO DROP ONCE THE PRECIPITATION BEGINS. MAX TEMPERATURES TODAY LOOK TO OCCUR CLOSE TO 6 PM. ..08.. PREV DISCUSSION... SYNOPSIS... 6Z SFC ANALYSIS HAS LOWS IN SOUTHEAST WYOMING AND EASTERN COLORADO WITH ASSOCIATED FRONTS CONNECTING THEM. A WEAK LOW WAS NEAR K9V9 IN SOUTH DAKOTA WITH A WARM FRONT RUNNING ROUGHLY ALONG THE MISSOURI RIVER INTO CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE GREAT LAKES WITH 20S AND HIGHER IN THE PLAINS AND LOWER MISSISSIPPI VALLEY. SHORT TERM...EARLY THIS MORNING AND TODAY... HEADLINES...HAVE TRANSITIONED TO A FREEZING RAIN ADVISORY FOR MOST OF THE AREA. AN ICE STORM WARNING HAS BEEN ISSUED FOR THE HWY 20 CORRIDOR FROM DBQ ON WEST. THERE SHOULD BE A QUICK ICE ACCUMULATION WITHIN THE FIRST COUPLE HOURS ONCE THE FREEZING RAIN BEGINS AT ANY ONE LOCATION. BASED ON CURRENT RADAR AND RAP TRENDS...FREEZING RAIN WILL BEGIN MOVING INTO THE FAR SOUTHWEST/WEST PARTS OF THE CWFA IN THE 10-12Z TIME FRAME. FCST SOUNDINGS SHOW CONSIDERABLE DRY AIR ACROSS THE AREA AND WBZ TEMPERATURES AT THE SFC AND 0.5 KM ARE BELOW FREEZING INITIALLY. THUS TREMENDOUS EVAPORATIVE COOLING WILL OCCUR TO HELP HOLD TEMPERATURES DOWN AND ALLOW SLEET TO MIX IN WITH THE FREEZING RAIN. BASED ON RAP TRENDS...TOP DOWN SATURATION WILL RAPIDLY OCCUR OVER ALL BUT THE FAR EASTERN PARTS OF THE CWFA BY MID MORNING. WBZ TEMPERATURES CONTINUE TO REMAIN BELOW FREEZING AT THE SFC AND AT 0.5 KM BUT WBZ TEMPERATURES SLOWLY RISE FROM SOUTHWEST TO NORTHEAST DURING THE MORNING. THUS FREEZING RAIN WITH SOME SLEET WILL BE SEEN ACROSS THE ENTIRE AREA DURING THE MORNING. TREMENDOUS WAA CONTINUES INTO THE AFTERNOON HOURS WHICH WILL ALLOW THE FREEZING RAIN/SLEET TO CHANGE OVER TO ALL RAIN FROM SOUTHWEST TO NORTHEAST. HOWEVER...MOST AREAS ALONG/NORTH OF HWY 30 WILL LIKELY SEE FREEZING RAIN/SLEET CONTINUE THROUGH THE AFTERNOON HOURS. DUE TO THE TREMENDOUS EVAPORATIVE COOLING THAT WILL OCCUR DURING THE DAY...TEMPERATURES MAY INITIALLY DROP SEVERAL DEGREES ONCE THE PRECIPITATION BEGINS. HOWEVER...THE SURGE OF MOISTURE MOVING NORTH INTO THE AREA WILL BODILY FORCE TEMPERATURES UP AGAIN AS THE DAY PROGRESSES. ..08.. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY... SUNDAY NIGHT THROUGH TUESDAY WILL BE A VERY ACTIVE PERIOD WITH CHALLENGING WEATHER THROUGHOUT. SUNDAY EVENING THE DAYTIME STORM SYSTEM GRADUALLY SHIFTS NORTHEAST. THE UPPER LEVEL SHORTWAVE SWEEPS NORTHEAST OF THE AREA...BUT THE STRONG WARM AIR ADVECTION AND MOISTURE ADVECTION CONTINUES AS A WEAK SURFACE LOW RIPPLES UP FROM KANSAS TO WISCONSIN OVERNIGHT. THE STRONG WARM AIR ADVECTION WILL CAUSE SURFACE TEMPERATURES TO CONTINUE TO WARM OVERNIGHT. WHILE TEMPERATURES ACROSS THE HIGHWAY 20 CORRIDOR WILL BE JUST BELOW FREEZING AS OF 00Z...THEY SHOULD RISE ABOVE FREEZING AROUND MID EVENING. THIS SHOULD END THE FREEZING RAIN THREAT FOR THE ENTIRE AREA BY 03Z TONIGHT. THUS...THE ENDING TIME OF THE NORTHERN MOST PORTIONS OF THE FREEZING RAIN ADVISORY AND ICE STORM WARNING. AFTERWARDS...A WEAK TROUGH MOVES ACROSS THE AREA OVERNIGHT. TEMPERATURES SHOULD REMAIN RELATIVELY WARM OVERNIGHT...ABOVE FREEZING. SO...WHILE I EXPECT SOME LINGERING LIGHT PRECIPITATION OVERNIGHT IN THE VICINITY OF THIS TROUGH AXIS...FREEZING RAIN SHOULD NOT BE A CONCERN. MONDAY AND TUESDAY THIS WEAK SURFACE TROUGH AXIS SAGS TO ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. AT UPPER LEVELS A LARGE SCALE TROUGH MOVES ACROSS THE ROCKIES MONDAY...AND OVER THE MIDWEST ON TUESDAY. THIS UPPER LEVEL TROUGH AND THE SOUTHWEST FLOW OVER THE MIDWEST AHEAD OF IT...IS EXPECTED TO GENERATE A NEW SURFACE LOW OVER EASTERN COLORADO...AND SWEEP NORTHEAST ACROSS IOWA OR WESTERN ILLINOIS ON TUESDAY. THE GFS IS THE FARTHEST WEST OF THE MODELS...AND RUNS THE SURFACE LOW OVER CENTRAL IOWA...WHILE THE NAM AND ECMWF ARE FARTHER EAST AND ARE CLOSER TO THE MISSISSIPPI RIVER. THIS IS GOING TO BRING ANOTHER SURGE OF WARM AIR INTO THE AREA MONDAY NIGHT AND TUESDAY...WITH HIGHS EXPECTED IN THE 40S AND 50S ON MONDAY AND TUESDAY...WITH VERY LARGE GRADIENTS ACROSS THE CWFA. WITH THE SURFACE LOW PASSAGE THERE SHOULD BE A SURGE OF RAINFALL...LIKELY WITH CONVECTIVE ELEMENTS EMBEDDED WITHIN IT. HAVE INCLUDED SOME ISOLATED THUNDER FOR PORTIONS OF THE AREA AS MID LEVEL LAPSE RATES AND THE DYNAMICS MAY BE ABLE TO SUPPORT SOME RUMBLES OF THUNDER. BEHIND THIS SURFACE LOW WE FINALLY GET THE COLD FRONT TO SWEEP THROUGH THE AREA...BRINGING MUCH COLDER AIR TO THE AREA TUESDAY NIGHT. WHILE I DO NOT EXPECT MUCH PRECIPITATION BEHIND THE COLD FRONT...WHAT IS THERE SHOULD GRADUALLY CHANGE OVER TO ALL SNOW OVERNIGHT. BY WEDNESDAY MORNING WE WILL BE BACK INTO THE COLD AIR AGAIN...WITH HIGHS ON WEDNESDAY IN THE 20S TO LOW 30S. STRONG COLD AIR ADVECTION THROUGH THE DAY WITH NORTHWEST FLOW BEHIND THE UPPER LEVEL TROUGH TO BRING A FRESH SURGE OF COLD AIR. THE 500MB COLD POOL IS PRETTY STEEP...SO WE MAY HAVE SOME INSTABILITY SHOWERS DURING THE DAY...BUT JUST ENOUGH UNCERTAINTY SO HAVE LEFT OUT FOR NOW. THURSDAY THROUGH SATURDAY THE MODELS KEEP US IN STRONG NORTHWEST FLOW WITH SOME HINTS AT A FAST MOVING SHORTWAVE TO DROP THROUGH AT SOME POINT. MODELS ARE QUITE DIFFERENT AT THIS TIME...AS CAN BE EXPECTED WITH SUCH A SMALL SCALE FEATURE. FOR NOW AM CARRYING SOME SLIGHT CHANCES FOR FRIDAY NIGHT AND SATURDAY...THOUGH WE MAY ALSO NEED SOME ON THURSDAY NIGHT AS WELL. TEMPERATURES WILL BE BACK TO COLDER THAN NORMAL VALUES FOR THIS TIME OF YEAR...WITH A WARM-UP EXPECTED ON SATURDAY TO NEAR NORMAL. LE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR JACKSON. FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR DES MOINES-HENRY IA-JEFFERSON-KEOKUK-LEE-VAN BUREN-WASHINGTON. FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR BENTON- CEDAR-CLINTON-IOWA-JOHNSON-JONES-LINN-LOUISA-MUSCATINE- SCOTT. ICE STORM WARNING UNTIL 9 PM CST THIS EVENING FOR BUCHANAN- DELAWARE-DUBUQUE. IL...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR CARROLL- JO DAVIESS-STEPHENSON. FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR HANCOCK- HENDERSON-MCDONOUGH-WARREN. FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR BUREAU- HENRY IL-MERCER-PUTNAM-ROCK ISLAND-WHITESIDE. MO...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR CLARK- SCOTLAND. && $$ NICHOLS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
105 PM MST SUN JAN 27 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY EVENING) ISSUED AT 1258 PM MST SUN JAN 27 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH EXTENDING FROM BRITISH COLUMBIA TO CENTRAL CALIFORNIA...WITH SW FLOW ACROSS THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS. SUBSIDENCE IS IN PLACE OVER CENTRAL KS AND CENTRAL CO WITH SEVERAL WEAK SHORTWAVES OVER THE NORTHERN PLAINS. A SURFACE TROUGH IS IN PLACE OVER THE CWA WITH A STALLED WARM FRONT JUST NORTHEAST OF THE CWA IN CENTRAL NEBRASKA. AREAS OF FOG/STRATUS MAY REDEVELOP OVERNIGHT TONIGHT PRIMARILY ALONG THE STATIONARY FRONT IN NEBRASKA...AND THEN SPREAD SW INTO OUR CWA. MOST GUIDANCE IS KEEPING FOG TO THE NORTH AND EAST OF THE CWA...HOWEVER LATEST 24HR RUC IS SHOWING FOG/STRATUS OVERSPREADING THE NE HALF OF CWA. WITH HIGHER TD VALUES POSSIBLY LINGERING ACROSS THE NE HALF OF THE CWA AND LOW LEVELS DECOUPLING...THE RUC SOLUTION SEEMS REASONABLE. ACROSS THE WEST AND SOUTH THE BL SHOULD BEGIN TO DRY OUT OVERNIGHT WITH S/SW FLOW...SO FOG POTENTIAL SHOULD BE MINIMAL CLOSER TO THE KS/CO STATE LINE. AS UPPER LEVEL TROUGH IN THE WEST SHIFTS WEST AND ASSOCIATED COLD FRONT PUSHES SOUTHEAST MONDAY...LEE TROUGH WILL STRENGTHEN WITH STRONG WAA AND BREEZY CONDITIONS ACROSS THE CWA. HIGH TEMP FORECAST IS COMPLICATED BY THE POSSIBILITY OF LINGERING STRATUS...AND INCREASING CLOUDS AS COLD FRONT AND UPPER TROUGH APPROACH CWA LATER IN THE AFTERNOON. WE COULD ALSO START TO SEE RAIN CHANCES INCREASE LATE IN THE AFTERNOON ACROSS THE NORTH/NORTHWEST. FOR NOW I KEPT HIGH TEMPS IN LINE WITH PREVIOUS FORECAST...WITH NEAR RECORD HIGHS IN THE MID TO UPPER 60S ACROSS NW KANSAS...AND SLIGHTLY COOLER TEMPS ACROSS THE NORTH. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 1258 PM MST SUN JAN 27 2013 LONGWAVE TROUGH WILL BRING A CHANCE OF LIGHT SNOW TO MOST OF THE AREA MONDAY NIGHT. BEST CHANCES WILL BE BEFORE MIDNIGHT...THEN GRADUALLY WINDING DOWN THROUGH TUESDAY MORNING. TOTAL SNOW AMOUNTS STILL ON TRACK TO BE AN INCH OR LESS...HIGHEST IN COLORADO. NORTHWEST FLOW ALOFT WILL BE IN PLACE THE REMAINDER OF THE PERIOD. VERY WEAK SYSTEM MAY BRING FLURRIES OR A LIGHT DUSTING WEDNESDAY NIGHT AND THURSDAY...OTHERWISE IT WILL BE DRY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW NORMAL EARLY IN THE PERIOD...BUT WARM TO AROUND 10 DEGREES ABOVE NORMAL BY THE WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1026 AM MST SUN JAN 27 2013 WITH WINDS EXPECTED TO BE 12KT OR LESS THROUGH THE PERIOD AT BOTH TERMINALS THE PRIMARY AVIATION FOCUS WILL BE ON CIG/VIS EARLY THIS AFTERNOON AND AGAIN EARLY MONDAY MORNING. CIG/VIS ALREADY VFR AT KGLD WITH ANOTHER AREA OF STRATUS OVER EASTERN COLORADO CURRENTLY EXPECTED TO DISSIPATE OVER THE NEXT FEW HOURS BEFORE HAVING A CHANCE TO IMPACT THE TERMINAL. VIS HAVE IMPROVED AT KMCK AND VFR VIS SHOULD BE EXPECTED BY 19Z. CIGS HAVE BEEN SLOWER TO IMPROVE AT KMCK WITH STRATUS LIKELY LINGERING THROUGH MID AFTERNOON BEFORE VFR CONDITIONS PREVAIL. AREAS OF STRATUS/FOG WILL REDEVELOP LATE TONIGHT OVER SW NEBRASKA AND NORTH CENTRAL KANSAS WHERE GOOD MOISTURE POOLING ALONG/NORTH OF STALLED WARM FRONT IS EXPECTED. I AM NOT CONFIDENT THAT THIS WILL AFFECT KGLD WITH SW FLOW BRINGING DRIER BL CONDITIONS. KMCK IS MOST LIKELY TO SEE REDUCED VIS/CIGS WITH LIFR CONDITIONS DEVELOPING BY 11Z AND IMPROVING BEFORE 16Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...024 AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1259 PM MST SUN JAN 27 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 1258 PM MST SUN JAN 27 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH EXTENDING FROM BRITISH COLUMBIA TO CENTRAL CALIFORNIA...WITH SW FLOW ACROSS THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS. SUBSIDENCE IS IN PLACE OVER CENTRAL KS AND CENTRAL CO WITH SEVERAL WEAK SHORTWAVES OVER THE NORTHERN PLAINS. A SURFACE TROUGH IS IN PLACE OVER THE CWA WITH A STALLED WARM FRONT JUST NORTHEAST OF THE CWA IN CENTRAL NEBRASKA. AREAS OF FOG/STRATUS MAY REDEVELOP OVERNIGHT TONIGHT PRIMARILY ALONG THE STATIONARY FRONT IN NEBRASKA...AND THEN SPREAD SW INTO OUR CWA. MOST GUIDANCE IS KEEPING FOG TO THE NORTH AND EAST OF THE CWA...HOWEVER LATEST 24HR RUC IS SHOWING FOG/STRATUS OVERSPREADING THE NE HALF OF CWA. WITH HIGHER TD VALUES POSSIBLY LINGERING ACROSS THE NE HALF OF THE CWA AND LOW LEVELS DECOUPLING...THE RUC SOLUTION SEEMS REASONABLE. ACROSS THE WEST AND SOUTH THE BL SHOULD BEGIN TO DRY OUT OVERNIGHT WITH S/SW FLOW...SO FOG POTENTIAL SHOULD BE MINIMAL CLOSER TO THE KS/CO STATE LINE. AS UPPER LEVEL TROUGH IN THE WEST SHIFTS WEST AND ASSOCIATED COLD FRONT PUSHES SOUTHEAST MONDAY...LEE TROUGH WILL STRENGTHEN WITH STRONG WAA AND BREEZY CONDITIONS ACROSS THE CWA. HIGH TEMP FORECAST IS COMPLICATED BY THE POSSIBILITY OF LINGERING STRATUS...AND INCREASING CLOUDS AS COLD FRONT AND UPPER TROUGH APPROACH CWA LATER IN THE AFTERNOON. WE COULD ALSO START TO SEE RAIN CHANCES INCREASE LATE IN THE AFTERNOON ACROSS THE NORTH/NORTHWEST. FOR NOW I KEPT HIGH TEMPS IN LINE WITH PREVIOUS FORECAST...WITH NEAR RECORD HIGHS IN THE MID TO UPPER 60S ACROSS NW KANSAS...AND SLIGHTLY COOLER TEMPS ACROSS THE NORTH. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1026 AM MST SUN JAN 27 2013 WITH WINDS EXPECTED TO BE 12KT OR LESS THROUGH THE PERIOD AT BOTH TERMINALS THE PRIMARY AVIATION FOCUS WILL BE ON CIG/VIS EARLY THIS AFTERNOON AND AGAIN EARLY MONDAY MORNING. CIG/VIS ALREADY VFR AT KGLD WITH ANOTHER AREA OF STRATUS OVER EASTERN COLORADO CURRENTLY EXPECTED TO DISSIPATE OVER THE NEXT FEW HOURS BEFORE HAVING A CHANCE TO IMPACT THE TERMINAL. VIS HAVE IMPROVED AT KMCK AND VFR VIS SHOULD BE EXPECTED BY 19Z. CIGS HAVE BEEN SLOWER TO IMPROVE AT KMCK WITH STRATUS LIKELY LINGERING THROUGH MID AFTERNOON BEFORE VFR CONDITIONS PREVAIL. AREAS OF STRATUS/FOG WILL REDEVELOP LATE TONIGHT OVER SW NEBRASKA AND NORTH CENTRAL KANSAS WHERE GOOD MOISTURE POOLING ALONG/NORTH OF STALLED WARM FRONT IS EXPECTED. I AM NOT CONFIDENT THAT THIS WILL AFFECT KGLD WITH SW FLOW BRINGING DRIER BL CONDITIONS. KMCK IS MOST LIKELY TO SEE REDUCED VIS/CIGS WITH LIFR CONDITIONS DEVELOPING BY 11Z AND IMPROVING BEFORE 16Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JTL AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1112 AM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 1112 AM MST SUN JAN 27 2013 I ALLOWED THE DENSE FOG ADVISORY TO EXPIRE WITH VISIBILITIES IMPROVED ACROSS THE AREA. AREAS OF STRATUS CONTINUE TO LINGER OVER PARTS OF THE AREA. IF STRATUS HOLDS WE COULD SEE HIGH TEMPS MUCH COOLER THAN ONGOING FORECAST BY 10-15F WHERE CLOUDS LINGER. SHORT RANGE GUIDANCE STILL INDICATES STRATUS CLEARING OVER THE NEXT FEW HOURS...WHICH SHOULD LEAVE ENOUGH TIME DURING PEAK HEATING TO REALIZE CURRENT FORECAST HIGHS. I ADJUSTED SKY COVER FORECAST...AND WILL HOLD OFF ON ADJUSTING TEMPS UNTIL I GET A BETTER HANDLE ON WHAT STRATUS WILL BE DOING OVER THE NEXT FEW HOURS. UPDATE ISSUED AT 844 AM MST SUN JAN 27 2013 CANCELLED ADVISORY FOR SHERMAN AND YUMA COUNTIES AND EXTENDED REMAINING ADVISORY THROUGH 18Z. BASED ON CURRENT TRENDS AND SHORT RANGE GUIDANCE I EXPECT DENSE FOG TO LINGER LONGER ACROSS MY NORTHEAST CWA. HRRR WHICH HAS BEST HAND ON CURRENT CONDITIONS SHOWS FOG DISSIPATING AROUND 18Z IN THE FAR NORTHEAST. THE WEST/SOUTHWEST EDGE OF FOG/STRATUS IS QUICKLY ERODING AND CONDITIONS HAVE IMPROVED. FURTHER IMPROVEMENT WILL BE EXPECTED FROM THE WEST TO THE EAST THROUGH THE REST OF THE MORNING. UPDATE ISSUED AT 702 AM MST SUN JAN 27 2013 HILL CITY AND WRAY HAVE BOTH REPORTED VISIBILITIES OF 1/4 MILE OR LESS SO HAVE ADDED THEM TO THE ADVISORY. UPDATE ISSUED AT 514 AM MST SUN JAN 27 2013 JUST ISSUED A DENSE FOG ADVISORY. AREAS OF DENSE FOG HAVE BECOME MORE WIDESPREAD OVER MOST OF EXTREME SOUTHWEST NEBRASKA AND THE FAR NORTH AND NORTHWEST PORTIONS OF NORTHWEST KANSAS. THESE CONDITIONS HAVE PERSISTED AND GOT WORSE. EVEN DESPITE OF DOWNSLOPE WINDS...ALBEIT LIGHT...THE DENSE FOG HAS CONTINUE. SMALL SCALE MODEL OUTPUT HAVING A DIFFICULT TIME GETTING A HANDLE ON THIS. RUC STARTED OUT WELL BUT IS NOW FADING. HRRR HAS BECOME MUCH BETTER IN DEPICTING THIS. SO IN ADDITION THE LOCATIONS ALREADY EXPERIENCING DENSE FOG...ALSO PUT THE ADVISORY INTO RED WILLOW AND NORTON COUNTIES PER OBSERVATIONAL TRENDS AND BEST MODEL OUTPUT. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 419 AM MST SUN JAN 27 2013 NUMEROUS FORECAST PROBLEMS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. FLOW IS SPLITTING OVER THE WESTERN PORTION OF THE COUNTRY. AN UNORGANIZED TROUGH WITH SMALLER WAVES WITHIN IT IS MOVING THROUGH THE AREA AT THIS TIME. THIS SYSTEM BROUGHT LIGHT RAIN TO THE AREA. THIS RAINFALL HAS MOVED NORTH OF THE AREA. MODELS INITIALIZED FINE ON THE JET. UPPER AIR ANALYSIS AND ESPECIALLY SATELLITE SHOWS THAT THE GFS AND ECMWF ARE HANDLING THE MID LEVELS THE BEST...ESPECIALLY IN OUR AREA. NAM DID NOT HAVE ANY PRECIPITATION OVER THE AREA TONIGHT. MODELS ARE HAVING A HARD TIME PLACING THE FOG AND STRATUS RIGHT NOW. MODELS WERE ALSO HAVING TROUBLE AT THE SURFACE. THE RUC AND ECMWF WERE DOING THE BEST. MODELS WERE CLOSE ON THE LOW LEVEL THERMAL FIELD WITH THE ECMWF AND UKMET DOING A LITTLE BETTER THAN THE GFS AND CANADIAN TODAY/TONIGHT...INITIAL PROBLEM WILL BE CLOUDS AND FOG. MODELS DOING A POOR JOB IN DEPICTING THIS REALITY AT THIS TIME. THE RUC AND TO A LESSER EXTENT THE HRRR IS GETTING THIS. PLAN ON WATCHING TRENDS AS LONG AS POSSIBLE BEFORE ADJUSTING THE BEST OUTPUT WITH THAT. MODELS HANG CLOUDS AROUND A WHILE. VERY DRY AIR PER SATELLITE AND ANALYSIS SHOULD QUICKLY WORK ITS WAY INTO THE AREA BY 18Z. SO EXPECT MOST OF THE CLOUD COVER AT ALL LEVELS TO BE GONE. LATEST GUIDANCE HAS BACKED OFF ON THE WINDS AND WILL ADJUST ACCORDINGLY. COMBINATION OF DOWNSLOPE WINDS AND LITTLE CLOUD COVER SHOULD ALLOW FOR A GOOD WARM UP. ANALYSIS SHOWS THAT AIR MASS WILL BE NEARLY THE SAME AS YESTERDAY. ALTHOUGH THE 06Z NAM BACKED OFF ITS EARLIER WARMER TEMPERATURES BUT IS STILL VERY MILD. HAVE KEPT THE MAXES THE NEARLY THE SAME BUT POTENTIAL THERE THAT MAXES COULD BE WARMER. LIGHT WINDS ON THE BACK SIDE OF THE SURFACE RIDGE DEVELOP OVER THE EASTERN HALF OR SO. BOUNDARY LAYER RH INCREASES IN THIS SAME AREA. AIR MASS LOOKS TO CHANGE LITTLE SO THAT MAKES SENSE. PREVIOUS FORECAST HAD FOG IN THERE AND LEFT THE FOG FORECAST ALONE. LIGHTER WINDS EAST WILL MAKE FOR COOLER MINS WITH WARMER MINS FURTHER WEST WITH DOWNSLOPING AND SOME WARM AIR ADVECTION. MONDAY/MONDAY NIGHT...LEFT THE MORNING FOG IN THERE. MAY HAVE SOME LOW LEVEL CLOUD COVER IN THERE WITH SOME INCREASE IN MID AND HIGH LEVEL CLOUD COVER. MODELS HAVE MAJOR DIFFERENCES IN THE AMOUNT OF WARMUP FOR THIS DAY. 06Z NAM HAS SLOWED ITS ARRIVAL OF THE COLD FRONT AND IS NOW NEAR TO SLIGHTLY SLOWER THAN THE ECMWF WHICH LOOKS BETTER IN HANDLING THIS. IN FACT THE ECMWF LOOKS THE FASTEST WITH REMAINING NEAR TO MUCH SLOWER THAN IT. AS A RESULT THE FRONT LOOKS TO ONLY MAKE IT INTO THE NORTHERN PORTION BY LATE IN THE DAY. IF THE CLOUDS DO NOT MESS UP THE TEMPERATURES...IT COULD END UP BEING VERY WARM ESPECIALLY IN THE SOUTHEAST HALF WHICH SHOULD GET THE WHOLE DAY OF HEATING. CONSIDERING THE TREND ON THE FRONTAL ARRIVAL AND THE INCREASE IN THE TEMPERATURE GUIDANCE...WARMED UP THE MAXES... ESPECIALLY IN THE SOUTHEAST WHICH COULD GET CLOSE TO 70. IF THIS SCENARIO PANS OUT...THE FAR WESTERN PORTION OF THE FORECAST AREA GETS CLOSE TO 20 PERCENT RELATIVE HUMIDITY AND GUSTS NEAR 25 MPH. THE DAY SHIFT WILL HAVE TO TAKE ANOTHER LOOK AT THIS. FRONT BLASTS THROUGH DURING THE NIGHT. GRADIENT AND RATHER HIGH 3 HOUR PRESSURE RISES WOULD INDICATE WINDY CONDITIONS DURING THE EVENING BEHIND THE FRONT. A RATHER STRONG SOUTHWEST TO NORTHEAST JET BEGINS TO MOVE ACROSS THE AREA DURING THE DAY AND EVENING. THIS PUTS THE SOUTHEAST HALF OF THE AREA IN THE RIGHT REAR QUADRANT DURING THE AFTERNOON AND INTO THE EVENING HOURS. EVEN THOUGH MAY BE HERE IN THE AFTERNOON...THE MOISTURE PROFILE DOES NOT SUPPORT ANY PRECIPITATION BEFORE 00Z. LIFT AND MOISTURE DO COME IN AFTER 00Z. HOWEVER THEY DO NOT SYNC UP WELL. THE LIFT AND EVEN SOME INSTABILITY ARE FURTHER TO THE EAST THAN THE DEEPEST MOISTURE. LIFT AND MOISTURE PROFILES MATCH UP WELL WITH THE DETERMINISTIC AND HPC QPF. THIS IS ALSO SUPPORTED BY THE GEFS/SREF PRECIPITATION PROBABILITIES. ALL THIS MEANS THAT THE NORTHWEST HALF WILL SEE THE BEST CHANCE OF PRECIPITATION. WITH ALL THE NEW DATA SUPPORTING THE CURRENT FORECAST VERY WELL...DID NOT MAKE ANY CHANGES TO IT. TUESDAY/TUESDAY NIGHT...AGAIN NEW GUIDANCE IS VERY SUPPORTIVE OF THE CHANCE OF PRECIPITATION/PRECIPITATION TYPE FORECAST THROUGH THE MORNING. SO LEFT THOSE GRIDS THROUGH 18Z ALONE. MOST OF THE LIFT AND MOISTURE IS GONE BY 18Z. LINGERING FLURRIES OR SPRINKLES IN THE AFTERNOON WILL BE MORE LIKELY THAN MEASURABLE SO MADE THAT CHANGE. COLD FRONT WILL BE SOUTH OF THE AREA BY THE BEGINNING OF THE DAY. DEFINITELY WILL BE COOLER WITH THE MODELS SURPRISINGLY IN GOOD AGREEMENT. PROBLEM IS THAT THE AGREEMENT IS WARMER THAN CURRENT FORECAST. WITH THE POSSIBILITY OF A DECENT AMOUNT OF SUN AND SOME DOWNSLOPE WINDS CAN DEFINITELY SEE THE WARMER TEMPERATURES. SO RAISED THE MAXES A LITTLE. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1026 AM MST SUN JAN 27 2013 WITH WINDS EXPECTED TO BE 12KT OR LESS THROUGH THE PERIOD AT BOTH TERMINALS THE PRIMARY AVIATION FOCUS WILL BE ON CIG/VIS EARLY THIS AFTERNOON AND AGAIN EARLY MONDAY MORNING. CIG/VIS ALREADY VFR AT KGLD WITH ANOTHER AREA OF STRATUS OVER EASTERN COLORADO CURRENTLY EXPECTED TO DISSIPATE OVER THE NEXT FEW HOURS BEFORE HAVING A CHANCE TO IMPACT THE TERMINAL. VIS HAVE IMPROVED AT KMCK AND VFR VIS SHOULD BE EXPECTED BY 19Z. CIGS HAVE BEEN SLOWER TO IMPROVE AT KMCK WITH STRATUS LIKELY LINGERING THROUGH MID AFTERNOON BEFORE VFR CONDITIONS PREVAIL. AREAS OF STRATUS/FOG WILL REDEVELOP LATE TONIGHT OVER SW NEBRASKA AND NORTH CENTRAL KANSAS WHERE GOOD MOISTURE POOLING ALONG/NORTH OF STALLED WARM FRONT IS EXPECTED. I AM NOT CONFIDENT THAT THIS WILL AFFECT KGLD WITH SW FLOW BRINGING DRIER BL CONDITIONS. KMCK IS MOST LIKELY TO SEE REDUCED VIS/CIGS WITH LIFR CONDITIONS DEVELOPING BY 11Z AND IMPROVING BEFORE 16Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...BULLER LONG TERM...JTL AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1026 AM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 844 AM MST SUN JAN 27 2013 CANCELLED ADVISORY FOR SHERMAN AND YUMA COUNTIES AND EXTENDED REMAINING ADVISORY THROUGH 18Z. BASED ON CURRENT TRENDS AND SHORT RANGE GUIDANCE I EXPECT DENSE FOG TO LINGER LONGER ACROSS MY NORTHEAST CWA. HRRR WHICH HAS BEST HAND ON CURRENT CONDITIONS SHOWS FOG DISSIPATING AROUND 18Z IN THE FAR NORTHEAST. THE WEST/SOUTHWEST EDGE OF FOG/STRATUS IS QUICKLY ERODING AND CONDITIONS HAVE IMPROVED. FURTHER IMPROVEMENT WILL BE EXPECTED FROM THE WEST TO THE EAST THROUGH THE REST OF THE MORNING. UPDATE ISSUED AT 702 AM MST SUN JAN 27 2013 HILL CITY AND WRAY HAVE BOTH REPORTED VISIBILITIES OF 1/4 MILE OR LESS SO HAVE ADDED THEM TO THE ADVISORY. UPDATE ISSUED AT 514 AM MST SUN JAN 27 2013 JUST ISSUED A DENSE FOG ADVISORY. AREAS OF DENSE FOG HAVE BECOME MORE WIDESPREAD OVER MOST OF EXTREME SOUTHWEST NEBRASKA AND THE FAR NORTH AND NORTHWEST PORTIONS OF NORTHWEST KANSAS. THESE CONDITIONS HAVE PERSISTED AND GOT WORSE. EVEN DESPITE OF DOWNSLOPE WINDS...ALBEIT LIGHT...THE DENSE FOG HAS CONTINUE. SMALL SCALE MODEL OUTPUT HAVING A DIFFICULT TIME GETTING A HANDLE ON THIS. RUC STARTED OUT WELL BUT IS NOW FADING. HRRR HAS BECOME MUCH BETTER IN DEPICTING THIS. SO IN ADDITION THE LOCATIONS ALREADY EXPERIENCING DENSE FOG...ALSO PUT THE ADVISORY INTO RED WILLOW AND NORTON COUNTIES PER OBSERVATIONAL TRENDS AND BEST MODEL OUTPUT. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 419 AM MST SUN JAN 27 2013 NUMEROUS FORECAST PROBLEMS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. FLOW IS SPLITTING OVER THE WESTERN PORTION OF THE COUNTRY. AN UNORGANIZED TROUGH WITH SMALLER WAVES WITHIN IT IS MOVING THROUGH THE AREA AT THIS TIME. THIS SYSTEM BROUGHT LIGHT RAIN TO THE AREA. THIS RAINFALL HAS MOVED NORTH OF THE AREA. MODELS INITIALIZED FINE ON THE JET. UPPER AIR ANALYSIS AND ESPECIALLY SATELLITE SHOWS THAT THE GFS AND ECMWF ARE HANDLING THE MID LEVELS THE BEST...ESPECIALLY IN OUR AREA. NAM DID NOT HAVE ANY PRECIPITATION OVER THE AREA TONIGHT. MODELS ARE HAVING A HARD TIME PLACING THE FOG AND STRATUS RIGHT NOW. MODELS WERE ALSO HAVING TROUBLE AT THE SURFACE. THE RUC AND ECMWF WERE DOING THE BEST. MODELS WERE CLOSE ON THE LOW LEVEL THERMAL FIELD WITH THE ECMWF AND UKMET DOING A LITTLE BETTER THAN THE GFS AND CANADIAN TODAY/TONIGHT...INITIAL PROBLEM WILL BE CLOUDS AND FOG. MODELS DOING A POOR JOB IN DEPICTING THIS REALITY AT THIS TIME. THE RUC AND TO A LESSER EXTENT THE HRRR IS GETTING THIS. PLAN ON WATCHING TRENDS AS LONG AS POSSIBLE BEFORE ADJUSTING THE BEST OUTPUT WITH THAT. MODELS HANG CLOUDS AROUND A WHILE. VERY DRY AIR PER SATELLITE AND ANALYSIS SHOULD QUICKLY WORK ITS WAY INTO THE AREA BY 18Z. SO EXPECT MOST OF THE CLOUD COVER AT ALL LEVELS TO BE GONE. LATEST GUIDANCE HAS BACKED OFF ON THE WINDS AND WILL ADJUST ACCORDINGLY. COMBINATION OF DOWNSLOPE WINDS AND LITTLE CLOUD COVER SHOULD ALLOW FOR A GOOD WARM UP. ANALYSIS SHOWS THAT AIR MASS WILL BE NEARLY THE SAME AS YESTERDAY. ALTHOUGH THE 06Z NAM BACKED OFF ITS EARLIER WARMER TEMPERATURES BUT IS STILL VERY MILD. HAVE KEPT THE MAXES THE NEARLY THE SAME BUT POTENTIAL THERE THAT MAXES COULD BE WARMER. LIGHT WINDS ON THE BACK SIDE OF THE SURFACE RIDGE DEVELOP OVER THE EASTERN HALF OR SO. BOUNDARY LAYER RH INCREASES IN THIS SAME AREA. AIR MASS LOOKS TO CHANGE LITTLE SO THAT MAKES SENSE. PREVIOUS FORECAST HAD FOG IN THERE AND LEFT THE FOG FORECAST ALONE. LIGHTER WINDS EAST WILL MAKE FOR COOLER MINS WITH WARMER MINS FURTHER WEST WITH DOWNSLOPING AND SOME WARM AIR ADVECTION. MONDAY/MONDAY NIGHT...LEFT THE MORNING FOG IN THERE. MAY HAVE SOME LOW LEVEL CLOUD COVER IN THERE WITH SOME INCREASE IN MID AND HIGH LEVEL CLOUD COVER. MODELS HAVE MAJOR DIFFERENCES IN THE AMOUNT OF WARMUP FOR THIS DAY. 06Z NAM HAS SLOWED ITS ARRIVAL OF THE COLD FRONT AND IS NOW NEAR TO SLIGHTLY SLOWER THAN THE ECMWF WHICH LOOKS BETTER IN HANDLING THIS. IN FACT THE ECMWF LOOKS THE FASTEST WITH REMAINING NEAR TO MUCH SLOWER THAN IT. AS A RESULT THE FRONT LOOKS TO ONLY MAKE IT INTO THE NORTHERN PORTION BY LATE IN THE DAY. IF THE CLOUDS DO NOT MESS UP THE TEMPERATURES...IT COULD END UP BEING VERY WARM ESPECIALLY IN THE SOUTHEAST HALF WHICH SHOULD GET THE WHOLE DAY OF HEATING. CONSIDERING THE TREND ON THE FRONTAL ARRIVAL AND THE INCREASE IN THE TEMPERATURE GUIDANCE...WARMED UP THE MAXES... ESPECIALLY IN THE SOUTHEAST WHICH COULD GET CLOSE TO 70. IF THIS SCENARIO PANS OUT...THE FAR WESTERN PORTION OF THE FORECAST AREA GETS CLOSE TO 20 PERCENT RELATIVE HUMIDITY AND GUSTS NEAR 25 MPH. THE DAY SHIFT WILL HAVE TO TAKE ANOTHER LOOK AT THIS. FRONT BLASTS THROUGH DURING THE NIGHT. GRADIENT AND RATHER HIGH 3 HOUR PRESSURE RISES WOULD INDICATE WINDY CONDITIONS DURING THE EVENING BEHIND THE FRONT. A RATHER STRONG SOUTHWEST TO NORTHEAST JET BEGINS TO MOVE ACROSS THE AREA DURING THE DAY AND EVENING. THIS PUTS THE SOUTHEAST HALF OF THE AREA IN THE RIGHT REAR QUADRANT DURING THE AFTERNOON AND INTO THE EVENING HOURS. EVEN THOUGH MAY BE HERE IN THE AFTERNOON...THE MOISTURE PROFILE DOES NOT SUPPORT ANY PRECIPITATION BEFORE 00Z. LIFT AND MOISTURE DO COME IN AFTER 00Z. HOWEVER THEY DO NOT SYNC UP WELL. THE LIFT AND EVEN SOME INSTABILITY ARE FURTHER TO THE EAST THAN THE DEEPEST MOISTURE. LIFT AND MOISTURE PROFILES MATCH UP WELL WITH THE DETERMINISTIC AND HPC QPF. THIS IS ALSO SUPPORTED BY THE GEFS/SREF PRECIPITATION PROBABILITIES. ALL THIS MEANS THAT THE NORTHWEST HALF WILL SEE THE BEST CHANCE OF PRECIPITATION. WITH ALL THE NEW DATA SUPPORTING THE CURRENT FORECAST VERY WELL...DID NOT MAKE ANY CHANGES TO IT. TUESDAY/TUESDAY NIGHT...AGAIN NEW GUIDANCE IS VERY SUPPORTIVE OF THE CHANCE OF PRECIPITATION/PRECIPITATION TYPE FORECAST THROUGH THE MORNING. SO LEFT THOSE GRIDS THROUGH 18Z ALONE. MOST OF THE LIFT AND MOISTURE IS GONE BY 18Z. LINGERING FLURRIES OR SPRINKLES IN THE AFTERNOON WILL BE MORE LIKELY THAN MEASURABLE SO MADE THAT CHANGE. COLD FRONT WILL BE SOUTH OF THE AREA BY THE BEGINNING OF THE DAY. DEFINITELY WILL BE COOLER WITH THE MODELS SURPRISINGLY IN GOOD AGREEMENT. PROBLEM IS THAT THE AGREEMENT IS WARMER THAN CURRENT FORECAST. WITH THE POSSIBILITY OF A DECENT AMOUNT OF SUN AND SOME DOWNSLOPE WINDS CAN DEFINITELY SEE THE WARMER TEMPERATURES. SO RAISED THE MAXES A LITTLE. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 419 AM MST SUN JAN 27 2013 THE LONGWAVE TROUGH THAT BROUGHT PRECIPITATION CHANCES EARLY THIS WEEK WILL BE OVER THE EASTERN HALF OF THE CONUS THROUGH FRIDAY. THE NORTHWEST UPPER LEVEL FLOW WILL ALLOW A COLD FRONT TO LINGER OVER THE NORTHEAST INTO FRIDAY. DURING THE WEEKEND THE UPPER LEVEL RIDGE OVER THE WEST COAST WILL BEGIN TO BUILD EAST INTO THE PLAINS. THURSDAY THE LONGWAVE TROUGH BROADENS AS A SHORT WAVE TROUGH MOVES THROUGH THE FLOW INTO THE PLAINS. PRECIPITATION CHANCES RETURN WEDNESDAY NIGHT AND THURSDAY AS THE SHORT WAVE TROUGH MOVES OVER THE FRONT AND 1000-500MB MOISTURE INCREASES. SNOW WEDNESDAY NIGHT WILL TRANSITION TO RAIN THURSDAY AFTERNOON AS TEMPERATURES WARM INTO THE MID/UPPER 30S TO AROUND 40. PRECIPITATION CHANCES COME TO AN END AS DRIER AIR FOLLOW THE SHORT WAVE TROUGH AXIS INTO THE AREA. SATURDAY ANOTHER SHORT WAVE TROUGH MOVES OVER THE AREA. HOWEVER 1000-500MB MOISTURE DECLINES AS THE TROUGH MOVES INTO THE PLAINS...SO THERE MAY ONLY BE ENOUGH MOISTURE FOR SOME CLOUDS TO DEVELOP BY THE TIME THE TROUGH ENTERS THE HIGH PLAINS. TEMPERATURES WILL BE BELOW NORMAL EAST OF THE COLD FRONT WITH NEAR NORMAL VALUES TO THE WEST THROUGH THURSDAY. NEAR TO ABOVE NORMAL TEMPERATURES WILL MOVE INTO THE AREA FRIDAY AND THE WEEKEND AS THE UPPER LEVEL RIDGE BUILDS EASTWARD. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1026 AM MST SUN JAN 27 2013 WITH WINDS EXPECTED TO BE 12KT OR LESS THROUGH THE PERIOD AT BOTH TERMINALS THE PRIMARY AVIATION FOCUS WILL BE ON CIG/VIS EARLY THIS AFTERNOON AND AGAIN EARLY MONDAY MORNING. CIG/VIS ALREADY VFR AT KGLD WITH ANOTHER AREA OF STRATUS OVER EASTERN COLORADO CURRENTLY EXPECTED TO DISSIPATE OVER THE NEXT FEW HOURS BEFORE HAVING A CHANCE TO IMPACT THE TERMINAL. VIS HAVE IMPROVED AT KMCK AND VFR VIS SHOULD BE EXPECTED BY 19Z. CIGS HAVE BEEN SLOWER TO IMPROVE AT KMCK WITH STRATUS LIKELY LINGERING THROUGH MID AFTERNOON BEFORE VFR CONDITIONS PREVAIL. AREAS OF STRATUS/FOG WILL REDEVELOP LATE TONIGHT OVER SW NEBRASKA AND NORTH CENTRAL KANSAS WHERE GOOD MOISTURE POOLING ALONG/NORTH OF STALLED WARM FRONT IS EXPECTED. I AM NOT CONFIDENT THAT THIS WILL AFFECT KGLD WITH SW FLOW BRINGING DRIER BL CONDITIONS. KMCK IS MOST LIKELY TO SEE REDUCED VIS/CIGS WITH LIFR CONDITIONS DEVELOPING BY 11Z AND IMPROVING BEFORE 16Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR KSZ001>004-014>016- 028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...DR SHORT TERM...BULLER LONG TERM...JTL AVIATION...DR
AREA FORECAST DISCUSSION
NWS JACKSON KY
534 PM EST SUN JAN 27 2013 .UPDATE... ISSUED AT 534 PM EST SUN JAN 27 2013 UPDATED TO SLOW DOWN PRECIPITATION ONSET. IT LOOKS LIKE THINGS ARE FINALLY STARTING TO SATURATE UP ENOUGH TO ALLOW FOR SOME LIGHT RAIN IN THE MONTICELLO/SOMERSET AREA SHORTLY. OTHERWISE...IT WILL REMAIN A SLOW PROCESS AS RAIN TRIES TO FIGHT TO THE LOW LEVEL DRY AIR. THE RAIN SHOULD EVENTUALLY WIN OUT...BUT STILL QUESTIONABLE IF THE SOUTHEAST WILL SEE MUCH IN THE WAY OF RAIN AS THERE WILL LIKELY BE A SOUTHEAST TO NORTHWEST GRADIENT FOR PLACES THAT RECEIVE RAIN VERSES THOSE WHO DO NOT. BASED ON LATEST RUC MODEL DATA...RAIN SHOULD BE ON THE WAY OUT BY 06Z WITH DRIER CONDITIONS EXPECTED FOR THE SECOND HALF OF THE NIGHT INTO TOMORROW MORNING. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 310 PM EST SUN JAN 27 2013 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY AS OF 20Z HAS PRECIP BEGINNING TO ENTER THE AREA NEAR SOMERSET AHEAD OF A DEVELOPING WARM FRONT. AT THIS POINT...SURFACE OBS HAVE SHOWN NO PRECIP MAKING IT TO THE GROUND IN THE SOUTH. BASED ON THE PERSISTENCE OF THE MODELS BRINGING IN THE PRECIP LATE THIS AFTERNOON AND INTO THE EARLY EVENING...WILL KEEP A SLIGHT CHANCE INTO THIS EARLY AFTERNOON WITH THE RAIN OVER SPREADING THE REST OF EASTERN KENTUCKY THIS EVENING. EXPECT RAIN TO CONTINUE THROUGH THE NIGHT. CONCERNS WITH THE TIMING OF THE PASSING WARM FRONT LOOK TO BE AROUND 12Z WITH A 30 TO 40 KNOT LL JET OVERHEAD. THIS WILL LEAD TO SOME 20 KNOT SOUTHWEST WINDS MIXING TO THE SURFACE FOR MONDAY. MORE SHOWERY PRECIP ENTERS THE AREA BY MONDAY AFTERNOON AS EASTERN KENTUCKY WILL BE IN THE WARM SECTOR FOR THE REST OF THE SHORT TERM. THE SURGE OF WARM AIR WILL BRING HIGHS FOR MONDAY INTO THE LOWER 60S...NEARLY 5 DEGREES SHORT OF RECORD VALUES. SHOWER ACTIVITY WILL CONTINUE THROUGH MONDAY NIGHT AS WELL WITH MODELS HANDLING THE SET UP QUITE WELL. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 351 PM EST SUN JAN 27 2013 THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE TIMING OF THE NEXT FRONT. THE LEADING EDGE OF THE FRONT IS GOING TO BRING SOME SHOWERS TO THE BLUEGRASS ON TUESDAY MORNING. AS THE FRONT GETS NEARER...SHOWERS WILL SPREAD ACROSS EASTERN KENTUCKY DURING THE TUESDAY EVENING. THE LATEST ECMWF IS SLOWING THIS DOWN A LITTLE...SO WILL NOT BE SURPRISED TO SEE THE FRONT SLOW DOWN AS THE TIME GETS NEARER. THE FRONT WILL ACTUALLY BE MOVING THROUGH THE AREA ON WEDNESDAY MORNING. THE NAM BUFR WAS SHOWING THE BEST INSTABILITY TO BE VERY NEAR THE FRONT ITSELF AND THIS IS WHERE THUNDERSTORMS WILL BE MOST LIKELY. THERE IS VERY STRONG SHEAR WITH THE FRONT...HOWEVER THE INSTABILITY IS MARGINAL...SO THE SEVERE POTENTIAL IS LOW...BUT NOT ZERO. IF THE FRONT SLOWS DOWN...THE THE SEVERE POTENTIAL WILL BE GREATER. WILL NEED TO BE VIGILANT TO SEE HOW THIS PLAYS OUT. ONCE THE POST FRONTAL SHOWERS MOVE INTO WEST VIRGINIA BY TUESDAY MORNING...THE WILL BE A SHORT RESPITE...UNTIL A CLIPPER SYSTEM MOVES THROUGH THE AREA ON THURSDAY NIGHT. THE LOOKS TO BE A LIGHT SNOWFALL WITH ABOUT AN INCH EXPECTED. THIS WOULD BE A STUDENTS DREAM AND GIVE THEM ANOTHER THREE DAY WEEKEND. HIGH PRESSURE WILL THEN DOMINATE UNTIL ANOTHER WEAK SYSTEM MOVES THROUGH THE AREA ON SATURDAY NIGHT. SO THIS WILL BE AN ACTIVE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1251 PM EST SUN JAN 27 2013 EXPECT CIRRUS TO CONTINUE TO OVER SPREAD EASTERN KENTUCKY THIS EVENING. BY 00Z MID AND LOW LEVEL CLOUD COVER WILL BEGIN TO MOVE INTO THE AREA. WHILE MOST CEILINGS WILL STILL BE VFR A FEW MVFR CEILINGS WILL MOVE INTO THE AREA ALONG WITH SOME MVFR VISIBILITY IN LIGHT RAIN. BY MONDAY AFTERNOON...SOUTHWEST WINDS WILL INCREASE TO 10 KNOTS AND GUSTING TO 20 AT TIMES. RAIN BY TOMORROW AFTERNOON SHOULD HAVE LIFTED OFF TO THE NORTH LEAVING VFR TO MVFR CEILINGS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...SHALLENBERGER LONG TERM....JJ AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
408 PM EST SUN JAN 27 2013 .SYNOPSIS... HIGH PRESSURE WILL SLIDE OFFSHORE TONIGHT AND EARLY MONDAY...AS A WARM FRONT LIFTS NORTH OF THE AREA LATE TONIGHT THROUGH MONDAY MORNING. THE NEXT COLD FRONTAL PASSAGE IS EXPECTED DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH MONDAY/... LATEST WX ANALYSIS SHOWS 1030+MB SFC HIGH PRESSURE OVER THE NE US, RIDGING DOWN THE EASTERN SEABOARD. TO THE WEST, COMPLEX WX SYSTEM ROLLING ACROSS THE MIDDLE AND UPPER MS VLY THIS AFTERNOON. ALOFT, DEEP TROUGH IS DIPPING ALONG THE WEST COAST, WHICH IS ALLOWING FOR INCREASED LONGWAVE RIDGING OVER THE EASTERN THIRD OF THE COUNTRY. A PAIR OF NOTABLE UPPER SHORTWAVES EVIDENT ON WV SAT THIS AFTN. FIRST ACROSS THE NORTHERN PLAINS/UPPER MIDWEST, WITH ANOTHER S/W SLIDING NE ACROSS THE LOWER OHIO VALLEY. IT IS THIS FEATURE THAT WILL NEED WATCHING FOR THE BALANCE OF THE NIGHT INTO TOMORROW. CLOUDS THAT WERE TRAPPED BENEATH LLVL INVERSION EARLIER TODAY HAVE ERODED OVER MUCH OF THE AREA. LAST VESTIGES OF LOW CLDS PUSHED OUT OF FAR WESTERN ZONES JUST IN TIME FOR SOME INCREASING MID/HI CLDS AHEAD OF THE OHIO VLY SYSTEM. WL ACCOUNT FOR SLOW INCREASE IN CLDS LATE TONIGHT TOWARDS MON MORNING. SFC HI PRESSURE WL VERY SLOWLY ERODE/MOVE OFF THE CST TNGT. HOWEVER AS PER USUAL WITH HIGH PRES WEDGED AGAINST THE MTNS, THIS WL OCCUR SLOWLY...AND LKLY SLOWER THAN CURRENTLY DEPICTED. CLOUDS WILL CONTINUE TO THICKEN AND LOWER AS SYSTEM AND ASSOCIATED WARM FRONT APPROACHES FM THE SW. TEMPS LKLY TO DROP THIS EVE/ERY TNGT INTO THE M/U20S...BEFORE HOLDING STEADY/SLOWLY RISING AFTER MIDNIGHT. FORECAST BUFR SOUNDINGS CONTINUE TO SHOW A RATHER STOUT WARM NOSE ALOFT...AROUND 4-5C SURGING INTO THE AREA AROUND THIS TIME, ALLOWING FOR ARRIVING OVERRUNNING MOISTURE TO FALL INTO A RELATIVELY SHALLOW SUB-FREEZING BOUNDARY LAYER. LOW LVLS REMAIN SLOW TO SATURATE BEFORE 09-14Z/28 OVR WESTERN/CENTRAL SECTIONS OF FA AS WAA ALOFT ENSUES IN EARNEST LATE TONIGHT. THUS, ANY FZRA WOULD OCCUR AFTER MIDNIGHT TNGT. UPSHOT OF THIS IS THAT ANY PCPN THAT FALLS PRIOR TO MID-MORNING MONDAY WILL MOST LIKELY BE FZRA, WITH PERHAPS SOME SLEET/IP AT THE START NW OF RIC. GENERAL MODEL AGREEMENT CONTINUES FOR SOME LGT PCPN REACHING FAR WESTERN COUNTIES BY DAYBREAK MON. QPF CONTINUES TO BE QUITE LIGHT...BUT SFC TEMPS LIKELY TO BE AOB FREEZING AS CAD WEDGE REMAINS STUBBORN. MONITORING UPSTREAM RADAR TRENDS...CONFIDENT IN RUC DEPICTION IN TAKING BEST SWATH/SLUG OF OVERRUNNING MOISTURE ALONG AND NORTH OF FVX-OFP LINE, AND HV ELEVATED TO LKLY POP ALONG AND NORTHWEST OF RIC METRO AREA. POTENTIAL ACCUM OF ICE LESS THAN A TENTH/FEW HUNDREDTHS OF AN INCH. HAVE ISSUED FZRA ADVY FOR AREAS ALONG AND NORTH OF I-85/WEST OF I-95. FARTHER E/SE...CONFIDENCE IN ACCUMULATING PCPN/ICE ACCRETION IS MUCH LOWER. EVENING CREW WILL CONTINUE MONITORING TRENDS, AND COULD ISSUE FARTHER EAST IF NEED BE. CAD WEDGE SLOWLY ERODES MONDAY, WITH TEMPS WARMING ABOVE FREEZING MON MORNING. ENDED HEADLINE AT 9AM AFTER COORD WITH NEIGHBORING OFFICES...AS BL SHOULD WARM TO AOA FREEZING BY THIS TIME. PCPN BEGINS TO MOVE TO THE ENE THROUGH/AWAY FM THE FA IN THE AFTN. SFC WARM FRONT NNE OF THE FA BY EVE...AND FA RMNS IN WRM SECTOR FOR MON NGT/TUE W/ VRB CLDNS. POPS IN THE AFTN TO BE GENLY AOB 14% S...AND ONLY SLGT CHC FAR N. HI TEMPS MON FM THE L40S N TO ARND 50F SE. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... WARM AIR QUICKLY STREAMS INTO THE AREA AS WARM FRONT SURGES NORTHWARD. WITH WEAK MIXING EXPECTED MON NIGHT AND EARLY ON TUESDAY WL NEED TO WATCH PROGRESS OF WEDGE ACROSS THE NORTHWEST, BUT FOR NOW INCRIMENTALLY NUDGED TEMPS UPWARDS. AS IS TYPICAL IN STRONG WAA SETUP SUCH AS THIS, SOME LOW STRATUS/FOG WL BE POSSIBLE LATE MON NIGHT AND TUE MORNING. OTHERWISE, ONCE LLVL INVERSION GETS BROKEN, EXPECT MARKEDLY WARMER CONDS ON TUESDAY AS SFC HIGH NUDGES FARTHER OFFSHORE AND WARM RETURN FLOW SETS UP. LO TEMPS MON NGT MNLY IN THE L/M40S. HIGHS IN THE U50S TO L60S. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... STRONG SHORTWAVE TROUGH AND ASSOCIATED SFC LOW WILL EJECT FROM THE DEEP SOUTH INTO THE MID ATLANTIC REGION WEDNESDAY AFTERNOON. SFC LOW WILL LOCATE OVER THE GREAT LAKES WITH THE COLD FRONT EXTENDING SW INTO THE LOWER MS RIVER VALLEY. WHILE TIMING AND SPATIAL DIFFERENCES STILL EXIST...ECMWF MORE AMPLIFIED AND SLIGHTLY SLOWER THAN GFS...A WARM/WET/WINDY DAY IS ON TAP FOR THE FA. DEEP SWLY FLOW WILL RESULT IN STRONG MOISTURE ADVECTION INTO THE REGION...ORIGINATING FROM THE GULF OF MEXICO (EVIDENT IN 700MB THETA E RIDGE). PRECIP WATERS WILL INCREASE TO AROUND 1.5" (OVER 2 STD ABOVE NORMAL FOR JANUARY). COLD FRONT EXPECTED TO CROSS THE FA WED LATE AFTERNOON THROUGH LATE WED NIGHT. DIVERGENCE ALOFT (RRQ OF 160+ KT 300MB JET) AND VORT MAX/SHORTWAVE WILL PROVIDE FORCING FOR ASCENT ACROSS THE REGION. MARGINAL LAPSE RATES...SHEAR AND LITTLE...IF ANY CAPE IN THE MIXED PHASE LAYER WILL LIKELY LIMIT CHANCE OF THUNDER WEDS AFTERNOON. WILL LEAVE OUT ANY MENTION OF THUNDER IN THE GRIDS/ZONES FOR NOW...BUT MAY NEED TO BE ADDED LATER WHEN MODELS HAVE A BETTER HANDLING ON THE DEVELOPING SYSTEM. HAVE INCREASED POPS TO CATEGORICAL WEDS AFTERNOON/EVENING ACROSS THE REGION. LIGHT SHOWERS WILL BE POSSIBLE WEDS MORNING/EARLY AFTERNOON ACROSS THE PIEDMONT. ABUNDANT MOISTURE AND STRONG FRONTOGENETIC FORCING COULD ALSO LEAD TO PERIODS OF MODERATE TO HEAVY RAINFALL ACROSS THE REGION. QPF AMOUNTS FORECAST TO GENERALLY RANGE FROM ONE QUARTER TO ONE HALF INCH WITH LOCALLY HIGHER AMOUNTS. PRECIP WILL END QUICKLY W TO E EARLY THURS MORNING AS DEEP...DRY WLY FLOW KICKS IN. STRONG WAA AND INCREASING HEIGHT/THICKNESS VALUES IN ADVANCE OF THE FRONT (850 TEMPS WARMING TO NEAR +14C) WILL RESULT IN A WARM/HUMID DAY. WHILE DAYTIME MIXING WILL BE WEAK WITH LACK OF SUNSHINE...BL WINDS WILL BE ENOUGH FOR SLY SFC WINDS 15 TO 20 MPH WITH GUSTS UP TO 25 MPH. WHILE CLOUD COVER/LACK OF STRONG MIXING WILL LIMIT TEMPS FROM REACHING THEIR FULL POTENTIAL...HIGHS STILL EXPECTED TO REACH INTO THE UPPER 60S/LOW 70S ACROSS THE FA. IN WAKE OF THE DEPARTING SYSTEM...TROUGHING WILL REMAIN OVER THE REGION THURSDAY AS HEIGHT/THICKNESS FALLS RESULT IN COLDER TEMPS THURSDAY (MID 40S N TO MID 50S). ADDITIONAL ENERGY WILL DIVE DOWN THE BACKSIDE OF THE TROUGH THURS AFTERNOON...LOCATING OVER THE OH VALLEY FRIDAY MORNING AS A WEAK LEE SIDE SFC TROUGH DEVELOPS. MOISTURE MAY BE A CONCERN...BUT HAVE OPTED TO MENTION SLIGHT CHANCE/CHANCE POPS ACROSS THE FA. PTYPE WILL BE A CONCERN...WITH SNOW SHOWERS POSSIBLE ACROSS THE NRN FA. ARCTIC HIGH PRESSURE WILL BUILD OVER THE MID ATLANTIC FRIDAY NIGHT INTO SATURDAY AS A CLIPPER SYSTEM DIVES OVER THE GREAT LAKES EARLY SATURDAY. TEMPS EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEKEND. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... SFC HIGH PRESSURE WILL SLIDE SE ACROSS THE AREA TODAY AND THEN MOVE OFF THE COAST THIS EVENING FOR CONTINUED VFR CONDITIONS. LIGHT AND VARIABLE WINDS WILL BECOME SE-S OVERNIGHT INTO MON. MEANWHILE...A WEAK UPPER LEVEL SYS WILL APPROACH THE AREA. THIS SYS COULD BRING SOME MVFR/IFR CONDS WITH -RA OR PSBL CHC FOR BRIEF WINTRY MIX EARLY MONDAY MORNING AS THE WARMER MOIST AIR OVER RUNS THE COOLER AIR AT THE SURFACE. THE FLOW TURNS MORE SOUTHERLY MONDAY AFTERNOON THROUGH WEDNESDAY WITH VFR CONDITIONS. THE ARRIVAL OF A COLD FRONT LATER WEDNESDAY INTO THURSDAY COULD PRODUCE MORE MVFR/IFR CONDITIONS ONCE AGAIN. && .MARINE... HIGH PRESSURE HAS SETTLED OVER THE WATERS THIS AFTERNOON RESULTING IN LIGHT N/NWLY WINDS. N/NE SWELL RESULTED IN A PERIOD OF HIGH SEAS OVER THE SRN COASTAL WATERS AND THE ISSUANCE OF SCA HEADLINES. SEAS HAVE REMAINED AROUND 4 FT...BUT ANTICIPATED TO REMAIN BELOW SCA CRITERIA. HIGH PRESSURE WILL SLIDE SE TONIGHT AND AS A WARM FRONT LIFTS THROUGH THE MID ATLANTIC. AS THIS OCCURS...FLOW WILL BECOME S/SW AND SUB SCA LEVELS. SW FLOW WILL INCREASE MONDAY AFTERNOON INTO MONDAY NIGHT TO AROUND 15 KT (15-20 KT OVER THE NRN COASTAL WATERS) AS LOW LEVEL PRESSURE GRADIENT TIGHTENS BTWN DEPARTING HIGH PRESSURE AND STRONG LOW PRESSURE OVER THE CNTRL CONUS. THE AFOREMENTIONED LOW PRESSURE SYSTEM WILL APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY...PUSHING A STRONG COLD FRONT TOWARD THE REGION LATE IN THE DAY. AHEAD OF THE FRONT...A STRONG LOW-LEVEL JET WILL DEVELOP OVER THE REGION AND THE WATERS. WHILE THE STRONGEST WINDS WILL REMAIN ALOFT (>40 KTS AT 1K FT)...ENOUGH WIND WILL REACH THE WATER LEVEL TO WARRANT SCA CONDITIONS OVER ALL WATERS INTO EARLY THURS MORNING. SEAS RAPIDLY BUILD WED AFTERNOON...REACHING UP TO 8 TO 10 FT 20 NM OUT LATE. COLD FRONT EXPECTED TO CROSS THE WATERS EARLY THURS MORNING ACCOMPANIED BY MODEST CAA. UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND AS A SERIES OF DISTURBANCES CROSS THE WATERS. ADDITIONAL SCA HEADLINES WILL LIKELY BE NEEDED THURSDAY AND FRIDAY...AND POSSIBLY INTO THE WEEKEND. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST MONDAY FOR VAZ048-049-060>071-079-080. MARINE...NONE. && $$ SYNOPSIS...MAM NEAR TERM...MAM/ALB SHORT TERM...MAM LONG TERM...SAM AVIATION...JEF MARINE...SAM
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
413 PM CST SUN JAN 27 2013 .DISCUSSION... QUITE THE INTERESTING SYSTEM UNFOLDING ACROSS THE AREA TODAY WITH INTENSE BAND OF SNOW WORKING ACROSS THE AREA THIS AFTERNOON WITHIN A STRONG ZONE OF FGEN IN THE H7-H6 LAYER. AS THIS STRONGER AND MORE PERSISTENT LIFT MOVED NORTH...THE AS ADVERTISED COLLAPSING OF THE WARM NOSE BACK BELOW FREEZING ALLOWED THE EARLY INITIAL PUSH OF FZRA/PL TO QUICKLY TRANSITION TO SNOW...AND QUITE THE IMPRESSIVE SNOW IT HAS BEEN. WITHIN THE MAIN BAND OF SNOW...RATES OF 1-2 INCHES PER HOUR HAVE BEEN QUITE COMMON. HERE AT THE OFFICE IN CHANHASSEN...WE GOT ABOUT 2.5 INCHES OF BETWEEN ABOUT 130 AND 330. THAT WOULD BE MORE SNOW IN 2 HOURS THAN WE HAVE SEEN IN THE REST OF THE MONTH COMBINED! THIS BAND OF SNOW WILL BE QUICKLY MOVING EAST WITH THE FGEN...WITH THE RAP SHOWING THE HEAVY SNOW SHOULD BE ALL BUT DONE IN THE TWIN CITIES BY 00Z...WITH IT NOT LASTING MUCH PAST 3Z IN THE LADYSMITH AREA. CURRENT GRIDS MAY NOT BE FAST ENOUGH IN CLEARING PRECIP OUT THIS EVENING...BUT THAT CAN BE UPDATED THROUGH THE EVENING. WHAT WILL BE TRICKY THOUGH...IS THAT AS THE MAIN PRECIP BATCH MOVES THROUGH...HAVE SEEN EXTENSIVE DZ/FG REPORTS ACROSS ERN NEB AND IA THAT WILL BE MOVING UP HERE THIS EVENING AND DO EXPECT A 2-4 HR WINDOW OF FZDZ BEHIND THE MAIN PRECIP BEFORE WE ARE LEFT WITH WHAT LOOKS TO BE A RATHER FOGGY NIGHT...WITH A DENSE FOG ADVY POSSIBLY IN THE BOOKS...THOUGH WILL WAIT UNTIL WINTER WEATHER HEADLINES ARE PULLED DOWN BEFORE ISSUING ANY DENSE FOG ADVISORIES. AS FOR THOSE WINTER WEATHER HEADLINES...ONLY CHANGE WAS TO TRIM A FEW COUNTIES OFF THE ADVY ON THE NW END WHERE PRECIP FAILED TO REACH AND MNDOT CONTINUES TO ADVERTISE GOOD TRAVEL CONDITIONS. DOUBT WE WILL HIT WINTER STORM WARNING CRITERIA FOR ANY ONE SPECIFIC TYPE OF PRECIPITATION /0.25 INCH OF FZRA AND 6 INCHES OF SNOW/...BUT THE COMBO OF A TENTH OF AN INCH OF FZRA BEING TOPPED WITH 3 TO 5 INCHES OF SNOW WARRANTS KEEPING THE WARNING GOING...THOUGH WOULD SUSPECT IT CAN BE PULLED BEFORE 6Z. WILL GET A BREAK IN THE PRECIP MOST OF THE DAY MONDAY...BEFORE THE MAIN TROUGH CURRENTLY ACROSS THE ROCKIES BEGINS PROGRESSING ACROSS THE PLAINS. WHAT WILL MAKE THIS PRECIP EVENT DIFFICULT FROM THE P-TYPE PERSPECTIVE IS THAT AS TODAYS PRECIP MOVES OUT...THE WARM NOSE WILL MOVE BACK IN...WITH ANOTHER MELTING LAYER IN PLACE MONDAY AFTERNOON AS THIS NEXT SYSTEM MOVES IN. MAIN SFC LOW IS FORECAST TO GO FROM NW KS MONDAY AFTERNOON TO THE U.P. OF MICH BY TUESDAY AFTERNOON. ALL MODELS SHOWING TWO BATCHES OF PRECIP WITH THIS SYSTEM. LLJ WARM SECTOR PRECIP LOOKS TO STAY WELL SE OF THE AREA...WHILE ANOTHER INTENSE BAND OF FGEN INDUCED SNOW MOVES ACROSS WRN INTO NE MN. WITH THIS SIGNAL...UPPED POPS TO THE CATEGORICAL RANGE IN THE NW CWA MONDAY NIGHT...WITH 2-3 INCHES OF SNOW UP IN THE MORRIS/ALEX AREA. CONFIDENCE ON PRECIP OCCURRENCE ACROSS THE REST OF THE AREA IS A BIT LOWER AS THESE TWO BATCHES OF PRECIP SPLIT THE AREA...BUT WHATEVER HAPPENS MONDAY NIGHT WITH PRECIP IN THE ERN 2/3RDS OF THE CWA...FORECAST SOUNDINGS AGAIN SAY THE P-TYPE WILL BE RA OR FZRA DEPENDING ON THE SFC TEMP. AFTER NEARLY STEADY TEMPERATURES TODAY THROUGH TUESDAY...THE ENCROACHMENT OF ANOTHER ARCTIC HIGH FOR THE END OF THE WEEK WILL LEAD TO A SIGNIFICANT COOL DOWN STARTING TUESDAY NIGHT. WILL SEE STRONG CAA ALL DAY WEDNESDAY RIGHT THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE GOES FROM THE DAKOTAS OVER TO THE KANSAS CITY AREA BY FRIDAY MORNING. WILL SEE ANOTHER HEALTHY SURGE OF COLD BEHIND THIS SYSTEM...WITH H85 TEMPS BY THURSDAY AGAIN BACK BETWEEN 25 C AND 30 C BELOW ZERO. THIS WILL GIVE MUCH OF THE MN CWA ANOTHER SHOT AT SEEING SUB ZERO HIGHS THURSDAY AFTERNOON. FOR FRIDAY THROUGH THE WEEKEND...A MODERATION IN TEMPERATURES IS EXPECTED AS A CLIPPER SLIDES ACROSS NRN MN AND WI FRI NIGHT/SATURDAY. MAY SEE A QUICK 1-2 INCHES OF SNOW OUT OF THIS WITH CURRENT INDICATIONS BEING THAT THE BEST CHANCE FOR ACCUMULATING SNOW WILL BE NORTH OF I-94. && .AVIATION.../18Z TAF ISSUANCE/ AREA OF -FZRAPL LIFTING NORTH/NORTHEAST AROUND 20 KNOTS PER RADAR TRENDS. THIS WILL WORK INTO ALL BUT PERHAPS KAXN BY LATE AFTERNOON. WILL CONTINUE TO MONITOR TRENDS. MODELS CONTINUE TO TREND TOWARD IFR/LIFR TO SNOW AFTER 20Z-21Z ACROSS MOST OF TAF SITES. HAVE INCLUDED THIS TREND AS WELL. LOOK FOR 3-5 INCHES SNOW ACCUMULATION NEAR KEAU WITH PERHAPS A COUPLE INCHES OF SNOW AND ONE TENTH INCH OF ICE OVER EAST CENTRAL MN. THE WINTRY MIX WILL END THIS EVENING WITH FOG AND PERHAPS FREEZING DRIZZLE COMMON DURING THE OVERNIGHT HOURS. WILL TREND SLOW IMPROVEMENT INTO MONDAY MORNING WITH PERHAPS LOW END MVFR INTO THE AFTERNOON. SOUTHEAST WINDS 10 KNOTS OR LESS MOST PLACES INTO TONIGHT BECOMING VARIABLE AND EVENTUALLY LIGHT SOUTHWEST TO WEST INTO MONDAY. KMSP...LIGHT FREEZING RAIN AND SLEET EXPECTED FOR A COUPLE HOURS OR SO...TRENDING TO SNOW THIS AFTERNOON INTO THE EARLY EVENING...PERHAPS ENDING AS FREEZING DRIZZLE OVERNIGHT. CEILINGS DROP TO IFR PERHAPS LIFR INTO TONIGHT AS SYSTEM MOVES THROUGH WITH VSBYS REMAINING AT LEAST MVFR THROUGH THE NIGHT INTO MONDAY MORNING. SLOW IMPROVEMENT TO LOW END MVFR INTO AFTERNOON. /OUTLOOK FOR KMSP/ MONDAY...IFR CIGS EARLY TRENDING MVFR CIGS/VSBYS IN THE AFTERNOON. S WIND 5 KTS. MONDAY NIGHT...MVFR CIGS EXPECTED. IFR CIGS AND MVFR VSBYS POSSIBLE. CHANCE OF RAIN AND SNOW. WIND LIGHT AND VARIABLE. TUESDAY...MVFR CIGS/VSBYS EXPECTED. IFR CONDITIONS POSSIBLE. CHANCE OF SNOW. W WIND 5 TO 10 KTS. TUESDAY NIGHT...MVFR CIGS POSSIBLE EARLY. CHANCE OF SNOW EARLY. NW WIND 10 TO 20 KT. WEDNESDAY...VFR CONDITIONS EXPECTED. NW WIND 15 TO 25 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ANOKA- BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-HENNEPIN-ISANTI- KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER- NICOLLET-RAMSEY-REDWOOD-RENVILLE-SCOTT-SHERBURNE-SIBLEY- WATONWAN-WRIGHT-YELLOW MEDICINE. WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR DAKOTA- FARIBAULT-FREEBORN-GOODHUE-RICE-STEELE-WASECA-WASHINGTON. WI...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR POLK. WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-RUSK-ST. CROIX. && $$ DWE/MPG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1252 PM CST SUN JAN 27 2013 .UPDATE... SENT AN UPDATE AT NOON TO EXPIRE MUCH OF THE DENSE FOG ADVISORY. IT HAS BEEN EXTENDED FOR THE TRI-CITIES AND SURROUNDING AREAS. VSBYS CONTINUE TO IMPROVE WITH HSI BEING THE ONLY HOLD-OUT BELOW 1/4 MILE. BECAUSE OF ABOVE NORMAL CONFIDENCE...WE ARE CONTEMPLATING ISSUING A DENSE FOG ADVISORY /FOR 10 PM TNGT TO NOON MON/ WITH THE 4 PM PACKAGE. ALL OF OUR NEB COUNTIES FOR SURE. STILL UNSURE ABOUT OUR N-CNTRL KS COUNTIES. WILL INCLUDE THE SCIENTIFIC REASONING WITH THE LATE AFTN AFD. && .PREV DISCUSSION... /ISSUED 1144 AM CST SUN JAN 27 2013/ AVIATION.../18Z GRI TAF THROUGH 18Z MONDAY AFTERNOON/ THIS AFTN: VLIFR CONDITIONS IN FOG EXPECTED TO GRADUALLY IMPROVE TO IFR BY 20Z AND MVFR BY 22Z. WE/RE SEEING THE W EDGE OF THE STRATUS ERODING JUST W OF BBW. SE WINDS BELOW 10 KTS SHIFTING TO SW. TNGT: WITH STRATUS ERODING LATE IN THE DAY...THE LOW-LEVELS WILL REMAIN CLOSE TO SATURATION. SO EXPECT ANY PERIOD OF VFR TO QUICKLY DECAY TO MVFR BY 03Z WITH FURTHER DEGRADATION TO VLIFR IN DENSE FOG. WINDS BECOME LIGHT AND VARIABLE. MON THRU 18Z: VLIFR REMAINS A PROBLEM FOR AIR TRAVEL THRU 18Z. EXPECT DENSE FOG CONTINUES THRU MIDDAY WITH GRADUAL IMPROVEMENT AFTER 18Z. WINDS LIGHT AND VARIABLE. CIG/VSBY CONFIDENCE: HIGH IN OCCURRENCE OF IFR LOW IN TIMING OF IMPROVEMENT THIS AFTN WIND CONFIDENCE: HIGH WX CONFIDENCE: HIGH PREV DISCUSSION... /ISSUED 1037 AM CST SUN JAN 27 2013/ 1037 AM UPDATE... HAVE DROPPED OUR KS COUNTIES FROM THE ADVISORY SINCE VIS SATL SHOWS A PERIOD OF CLEARING. ANOTHER AREA OF STRATUS IS MOVING INTO PHILLIPS COUNTY AND WILL BE MOVING INTO ROOKS COUNTY WITHIN THE HOUR. UNSURE HOW THIS EVOLVES BUT IT COULD PUT A DAMPER ON OUR FCST HIGH TEMPS. AS WE MENTIONED YESTERDAY...THERE IS ROOM FOR CONSIDERABLE BUST POTENTIAL IN TEMPS NEAR THE BOUNDARY OF OVC VS CLR. IN COORDINATION WITH LBF...HAVE EXTENDED MENTION OF PATCHY FOG 12PM-3PM AS A BUFFER FROM THE WIDESPREAD DENSE FOG MENTION WHICH ENDS AT NOON. HAVE ALSO LOWERED HOURLY TEMPS N OF I-80 FOR THE NEXT 3 HRS. WE ARE SEEING BREAK IN THE OVC /BINOVC/ JUST NW OF BBW AND LBF. SO THIS SHOULD ALLOW FOR SOME INCREASE IN TEMPS AS THE DAY PROGRESSES. HAVE MADE SOME HOURLY ADJUSTMENTS TO SKY FCST THRU 00Z. ALL UPDATED PRODUCTS ARE OUT AND PUBLISHED TO THE WEB. PREV DISCUSSION... /ISSUED 847 AM CST SUN JAN 27 2013/ 846 AM UPDATE...VISIBILITIES CONTINUE TO DECAY. SO ISSUED A DENSE FOG ADVISORY UNTIL NOON. FOG WILL LINGER IN SOME AREAS PAST NOON...BUT VSBYS WILL IMPROVE TO MORE THAN A QUARTER MILE. NPW/ZFP ARE OUT. HWO/EHWO WILL POST SHORTLY. PREV DISCUSSION... /ISSUED 449 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT. MOST OF THE MEASURABLE RAIN WILL HAVE EXITED OUR CWA TO THE NORTHEAST BY SUNRISE...BUT DRIZZLE AND FOG WILL STILL BE A FACTOR FOR SOME AREAS TODAY. THE TEMPERATURE FORECAST IS A BIG CHALLENGE...BUT EXPECT GENERALLY ABOVE NORMAL TEMPERATURES THROUGH TUESDAY. A SECOND STORM SYSTEM WILL ENTER OUR FORECAST AREA MONDAY NIGHT AND BRING WITH IT A CHALLENGING MIXED PRECIPITATION TYPE FORECAST. TODAY...THERE ARE NUMEROUS FORECAST CONCERNS CENTERED AROUND POSSIBLE FOG...A STRATUS DECK THAT WILL BE DIFFICULT TO SHAKE ESPECIALLY ACROSS NEBRASKA ZONES...A SHARP TEMPERATURE GRADIENT...AND EVEN SOME PATCHY DRIZZLE. THE SREF AND HRRR ARE BOTH INDICATING THE POSSIBILITY OF FOG BEHIND THE DEPARTING RAIN BAND WITH THE POTENTIAL OF VISIBILITY REDUCTIONS TO LESS THAN ONE QUARTER MILE. THIS FOG HAS YET TO MATERIALIZE THUS FAR THIS MORNING...BUT CEILING HEIGHTS HAVE BEEN FALLING AND THE WIND WILL BEGIN TO DIE DOWN SOME ACROSS OUR WEST AFTER SUNRISE. THEREFORE...WILL CONTINUE TO INCLUDE POSSIBLE FOG IN OUR FORECAST FOR THIS MORNING. THERE HAS BEEN SOME DRIZZLE BEHIND THE RAIN BAND AND THIS IS ALSO LIKELY TO CONTINUE THROUGH AT LEAST A PORTION OF THE MORNING ESPECIALLY ACROSS EASTERN ZONES. THE DRIZZLE MAY EVEN LINGER OVER OUR FAR EAST THROUGH EARLY THIS AFTERNOON. MOST FORECAST MODELS BRING THE CLEARING LINE INTO KANSAS THIS AFTERNOON BUT KEEP MOST NEBRASKA ZONES SOCKED IN UNDER A LOW STRATUS DECK. THUS THERE WILL BE A TIGHT TEMPERATURE GRADIENT ALONG THE EDGE OF THIS STRATUS DECK...WHICH SHOULD BE LOCATED SOMEWHERE NEAR THE NEBRASKA KANSAS BORDER THIS AFTERNOON. TONIGHT...THE WET GROUND FROM THE RECENT RAIN ALONG WITH LIGHT AND VARIABLE WINDS WILL MAKE FOG POSSIBLE. THEREFORE...WILL CONTINUE TO CALL FOR AT LEAST THE POSSIBILITY OF SOME FOG LATE TONIGHT INTO EARLY MONDAY MORNING. MONDAY...THE NEXT UPPER TROUGH WILL BE DIGGING ACROSS THE WESTERN CONUS WITH AN ASSOCIATED SFC LOW DEVELOPING OVER EASTERN COLORADO. THE WIND WILL BE SOUTHERLY ACROSS THE PLAINS AHEAD OF THIS LOW AND WE SHOULD WARM UP NICELY WITH HIGH TEMPERATURES POTENTIALLY WELL ABOVE NORMAL. HOWEVER...THERE IS UNCERTAINTY IN THE LOW CLOUD FORECAST ON MONDAY...WHICH IF PRESENT...THESE LOW CLOUDS WOULD REALLY HAMPER OUR WARM UP. MONDAY NIGHT INTO TUESDAY...THE UPPER WAVE AND SFC LOW WILL PRESS THROUGH OUR FORECAST AREA WITH A COLD FRONT SWEEPING THROUGH. THIS IS A PROGRESSIVE FAST MOVING OPEN WAVE. THUS ANY DEFORMATION SNOW BAND WILL BE WEAK WITH LITTLE IF ANY SNOW ACCUMULATION. THE 00Z ECMWF AND 00Z GFS PLACE A BAND OF RAIN AND SNOW ACROSS OUR NORTHWEST ZONES MONDAY EVENING...WHICH SHOULD TURN OVER TO ALL SNOW AT SOME POINT AFTER MIDNIGHT. THIS BAND HEADS MORE NORTHEAST RATHER THAN SOUTHEAST...AND OUR SOUTHEAST ZONES MAY STAY COMPLETELY DRY. THE MOST AGGRESSIVE MODEL GENERALLY IS CALLING FOR ONE INCH OR LESS OF SNOW ACROSS OUR NORTHWEST...SO THIS IS NOT APPEARING TO BE A BIG DEAL FOR OUR AREA. TUESDAY WILL BE COOLER BEHIND THE COLD FRONT...BUT STILL ABOVE NORMAL AS THE COLDER AIR WILL TAKE SOME TIME TO SETTLE IN. LONG TERM...WEDNESDAY THROUGH SATURDAY. OVERALL NO MAJOR CHANGES TO THESE 4 DAYS FROM PREVIOUS FORECAST...ALTHOUGH A SLIGHT CHANCE OF SNOW HAS BEEN INTRODUCED FOR PARTS OF THE CWA THURSDAY...AND HIGH TEMPS FOR FRIDAY CONTINUE TO TREND UP A BIT. CONFIDENCE IS FAIRLY HIGH THAT THE MAJORITY OF THIS TIME FRAME IS PRECIPITATION FREE EXCEPT FOR MAYBE THURSDAY...WHICH ALSO LOOKS LIKE THE COLDEST DAY OF THE UPCOMING WEEK. STARTING OFF WEDNESDAY/WED NIGHT...00Z ECMWF/GFS RUNS ARE IN GOOD AGREEMENT ON THE BIG PICTURE. ALOFT DURING THE DAY...THE LOCAL AREA WILL SEE NORTHWEST FLOW BEHIND THE DEPARTURE OF A LARGE SCALE TROUGH AXIS THAT EXTENDS NORTH-SOUTH THROUGH THE HEART OF THE NATION...WITH THIS TROUGH AXIS PROGRESSING EAST TOWARD THE EASTERN MIDWEST/OHIO VALLEY REGION BY DAYS END. THEN ON WED NIGHT...A SHORTWAVE TROUGH DROPS SOUTHWARD OUT OF CANADA INTO THE DAKOTAS...REINFORCING THE TROUGHY PATTERN DOMINATING THE MAJORITY OF THE CONUS BY THIS TIME. CONFIDENCE IS FAIRLY HIGH IN A PRECIPITATION-FREE 24 HOURS HERE...AT LEAST OF THE MEASURABLE VARIETY...ALTHOUGH WOULD NOT BE SURPRISED TO SEE A FEW FLURRIES STILL BRUSHING EASTERN ZONES DURING THE DAY...AND THEN ANOTHER BATCH OF FLURRIES/LIGHT SNOW POSSIBLY APPROACHING NORTHERN/WESTERN COUNTIES LATE WEDNESDAY NIGHT...BUT BOTH OF THESE POSSIBILITIES SEEM LOW ENOUGH FOR NOW TO LEAVE OUT. TEMP-WISE...MADE VERY LITTLE IF ANY CHANGE TO PREVIOUS FORECAST...AS WEDNESDAY SHOULD BE ROUGHLY 10 DEGREES COOLER THAN TUESDAY IN THE WAKE OF THE FIRST OF TWO MID-WEEK COLD FRONTS. HIGHS ARE AIMED TO RANGE FROM MID-UPPER 20S FAR NORTHEAST...NEAR 30 TRI-CITIES...MID- UPPER 30S SOUTHWEST. THURSDAY/THURS NIGHT...HAVE INTRODUCED A SLIGHT CHANCE OF SNOW FOR ROUGHLY THE SOUTHWEST 1/3 OF THE CWA FOR THE DAYTIME HOURS...AND WOULD NOT BE SURPRISED TO SEE THIS SLIGHT CHANCE OF SNOW OR AT LEAST FLURRIES EXPANDED TO COVER MORE OF OUR AREA IN LATER FORECASTS IF TRENDS FROM THE 00Z ECMWF/GEM CONTINUE. IN SHORT...THIS LOOKS LIKE A FAVORABLE SETUP FOR A QUICK-HITTING MINOR SNOW ACCUMULATION...AS THE AFOREMENTIONED NORTHWEST-FLOW SHORTWAVE TROUGH THAT DROPS INTO THE DAKOTAS WED NIGHT CONTINUES TO SINK SOUTHEAST ACROSS EASTERN NEB/IA ON THURSDAY...AND A NORTH- SOUTH ORIENTED UPPER JET STREAK APPROACHES OUR LOCAL AREA FROM THE NORTHWEST...HELPING FOCUS A BAND OF MID LEVEL LIFT/SATURATION. NOT LOOKING LIKE HIGH-IMPACT BY ANY MEANS...BUT SOMETHING TO KEEP AN EYE ON. BY THURSDAY NIGHT...FORCING FOR ANY NUISANCE SNOW SHOULD HAVE MOVED OFF TO THE SOUTHEAST. IN THE LOW LEVELS...THE SECOND AND STRONGER COLD FRONT OF THE WEEK ENTERS THE CWA DURING THE DAY...ALTHOUGH THE CORE OF THE TRULY COLD AIR SHOULD REMAIN AT LEAST A FEW HUNDRED MILES TO OUR NORTHEAST...MUCH AS SEEN WITHIN THE PAST WEEK. CERTAINLY THIS WILL RESULT IN A SHARP AND HARD-TO- PIN-DOWN SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT FOR HIGHS ON THURSDAY...AND HAVE SHAVED A COUPLE DEGREES OFF PREVIOUS FORECAST ALL AREAS...AIMING FOR A RANGE FROM NEAR 20 FAR NORTHEAST...MID- UPPER 20S TRI-CITIES AND MID 30S SOUTHWEST. MUCH COLDER AIR WILL NOT BE FAR AWAY...WITH SINGLE DIGIT HIGHS POSSIBLY AS CLOSE AS FAR NORTHEAST NEB...SO WOULD NOT BE SURPRISED TO SEE THIS COLDER AIR PUSH SOUTHWEST INTO OUR AREA A BIT MORE AGGRESSIVELY THAN CURRENTLY ADVERTISED. FRIDAY/FRIDAY NIGHT...THE REGION REMAINS IN WEST-NORTHWEST FLOW ALOFT...AS A COUPLE SHORTWAVE TROUGHS PASS THROUGH THE FLOW...ONE STAYING WELL NORTH FROM CANADA INTO THE NORTHERN GREAT LAKES...AND THE OTHER SLIDING INTO OR JUST SOUTHWEST OF THE AREA. AT THIS TIME...NOTHING APPEARS STRONG ENOUGH TO GENERATE PRECIP FOR OUR CWA. THE BIGGER STORY IS A POTENTIALLY DECENT WARM-UP OVER THURSDAY...AS THE COLD LOW LEVEL RIDGE AXIS SLIDES EAST AND ALLOWS WARMER AIR TO INVADE THE CENTRAL PLAINS ON WESTERLY OR SOUTHERLY BREEZES. HAVE RAISED FRIDAY HIGHS 3-4 DEGREES FROM PREVIOUS FORECAST PER MULTI-MODEL ALLBLEND...NOW RANGING FROM MID 30S NORTHEAST TO LOW-MID 40S SOUTHWEST. SATURDAY CURRENTLY HAS RATHER HIGH CONFIDENCE OF BEING PRECIP-FREE...AND IS ALSO LOOKING LIKE THE WARMEST DAY SINCE MONDAY...AND MADE ALMOST NO CHANGE TO PREVIOUS HIGHS RANGING FROM MID 40S NORTHEAST TO UPPER 40S/LOW 50S SOUTH AND WEST. THE ECWMF SUGGESTS THERE COULD BE A DECENT NORTHWEST BREEZE AS THE REGION IS GLANCED BY A THE EDGES OF A WEAK COLD FRONT DRIVEN BY ANOTHER GREAT LAKES SHORTWAVE TROUGH...BUT EVEN SO DECENT MIXING AND A DOWNSLOPE WIND COMPONENT WOULD HELP AID A WARM-UP. && .GID WATCHES/WARNINGS/ADVISORIES... NE...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR NEZ039-040- 046>048-061>064-074>077-084>086. KS...NONE. && $$ UPDATE...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1144 AM CST SUN JAN 27 2013 .AVIATION.../18Z GRI TAF THROUGH 18Z MONDAY AFTERNOON/ THIS AFTN: VLIFR CONDITIONS IN FOG EXPECTED TO GRADUALLY IMPROVE TO IFR BY 20Z AND MVFR BY 22Z. WE/RE SEEING THE W EDGE OF THE STRATUS ERODING JUST W OF BBW. SE WINDS BELOW 10 KTS SHIFTING TO SW. TNGT: WITH STRATUS ERODING LATE IN THE DAY...THE LOW-LEVELS WILL REMAIN CLOSE TO SATURATION. SO EXPECT ANY PERIOD OF VFR TO QUICKLY DECAY TO MVFR BY 03Z WITH FURTHER DEGRADATION TO VLIFR IN DENSE FOG. WINDS BECOME LIGHT AND VARIABLE. MON THRU 18Z: VLIFR REMAINS A PROBLEM FOR AIR TRAVEL THRU 18Z. EXPECT DENSE FOG CONTINUES THRU MIDDAY WITH GRADUAL IMPROVEMENT AFTER 18Z. WINDS LIGHT AND VARIABLE. CIG/VSBY CONFIDENCE: HIGH IN OCCURRENCE OF IFR LOW IN TIMING OF IMPROVEMENT THIS AFTN WIND CONFIDENCE: HIGH WX CONFIDENCE: HIGH && .PREV DISCUSSION... /ISSUED 1037 AM CST SUN JAN 27 2013/ 1037 AM UPDATE... HAVE DROPPED OUR KS COUNTIES FROM THE ADVISORY SINCE VIS SATL SHOWS A PERIOD OF CLEARING. ANOTHER AREA OF STRATUS IS MOVING INTO PHILLIPS COUNTY AND WILL BE MOVING INTO ROOKS COUNTY WITHIN THE HOUR. UNSURE HOW THIS EVOLVES BUT IT COULD PUT A DAMPER ON OUR FCST HIGH TEMPS. AS WE MENTIONED YESTERDAY...THERE IS ROOM FOR CONSIDERABLE BUST POTENTIAL IN TEMPS NEAR THE BOUNDARY OF OVC VS CLR. IN COORDINATION WITH LBF...HAVE EXTENDED MENTION OF PATCHY FOG 12PM-3PM AS A BUFFER FROM THE WIDESPREAD DENSE FOG MENTION WHICH ENDS AT NOON. HAVE ALSO LOWERED HOURLY TEMPS N OF I-80 FOR THE NEXT 3 HRS. WE ARE SEEING BREAK IN THE OVC /BINOVC/ JUST NW OF BBW AND LBF. SO THIS SHOULD ALLOW FOR SOME INCREASE IN TEMPS AS THE DAY PROGRESSES. HAVE MADE SOME HOURLY ADJUSTMENTS TO SKY FCST THRU 00Z. ALL UPDATED PRODUCTS ARE OUT AND PUBLISHED TO THE WEB. PREV DISCUSSION... /ISSUED 847 AM CST SUN JAN 27 2013/ 846 AM UPDATE...VISIBILITIES CONTINUE TO DECAY. SO ISSUED A DENSE FOG ADVISORY UNTIL NOON. FOG WILL LINGER IN SOME AREAS PAST NOON...BUT VSBYS WILL IMPROVE TO MORE THAN A QUARTER MILE. NPW/ZFP ARE OUT. HWO/EHWO WILL POST SHORTLY. PREV DISCUSSION... /ISSUED 631 AM CST SUN JAN 27 2013/ AVIATION...12Z KGRI TAF. WILL STATE OFF THE TOP THAT THIS WILL BE A CHALLENGING 24 HOURS IN TERMS OF PINNING DOWN THE TIMING OF CEILING/VISIBILITY CHANGES...BUT THE BOTTOM LINE IS THAT A GOOD CHUNK OF THE PERIOD WILL SEE DEGRADED FLIGHT CATEGORIES RANGING BETWEEN LIFR AND MVFR. STARTING OFF RIGHT AWAY THIS MORNING...IFR/LIFR CONDITIONS ARE FIRMLY IN PLACE...AND THIS IS LIKELY TO PERSIST THROUGH MOST/ALL OF THE MORNING HOURS AS A SATURATED LOW LEVEL AIRMASS PERSISTS IN THE PRESENCE OF LIGHT SOUTHERLY BREEZES. WOULD NOT BE SURPRISED TO EVEN SEE A BRIEF PERIOD OF VLIFR CONDITIONS IN DENSE FOG. THIS AFTERNOON...ANTICIPATE VISIBILITY TO GRADUALLY IMPROVE INTO MVFR THEN VFR TERRITORY...WHILE CEILING TRENDS GRADUALLY IMPROVE TO LOW-END MVFR BY MID-LATE AFTERNOON. AS LOW LEVEL FLOW TURNS MORE WESTERLY LATE IN THE AFTERNOON/EARLY THIS EVENING ...HAVE REASONABLE CONFIDENCE THAT THERE SHOULD BE AT LEAST A 6 HOUR PERIOD OF VFR CONDITIONS AS THE LOW LEVEL CEILING FINALLY LIFTS/SCATTERS OUT. ATTENTION THEN TURNS TO THE LATE NIGHT HOURS...WHEN A LIGHT AND VARIABLE WIND REGIME ALONG WITH WET GROUND WILL LIKELY FOSTER THE REDEVELOPMENT OF FOG...ALTHOUGH TO WHAT EXTENT IS STILL UNKNOWN. FOR NOW...WILL ADVERTISE PREVAILING IFR CONDITIONS DURING THE LAST FEW HOURS OF THE PERIOD...AND DEFER TO LATER FORECASTS TO FINE TUNE THE DETAILS. PREV DISCUSSION... /ISSUED 449 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT. MOST OF THE MEASURABLE RAIN WILL HAVE EXITED OUR CWA TO THE NORTHEAST BY SUNRISE...BUT DRIZZLE AND FOG WILL STILL BE A FACTOR FOR SOME AREAS TODAY. THE TEMPERATURE FORECAST IS A BIG CHALLENGE...BUT EXPECT GENERALLY ABOVE NORMAL TEMPERATURES THROUGH TUESDAY. A SECOND STORM SYSTEM WILL ENTER OUR FORECAST AREA MONDAY NIGHT AND BRING WITH IT A CHALLENGING MIXED PRECIPITATION TYPE FORECAST. TODAY...THERE ARE NUMEROUS FORECAST CONCERNS CENTERED AROUND POSSIBLE FOG...A STRATUS DECK THAT WILL BE DIFFICULT TO SHAKE ESPECIALLY ACROSS NEBRASKA ZONES...A SHARP TEMPERATURE GRADIENT...AND EVEN SOME PATCHY DRIZZLE. THE SREF AND HRRR ARE BOTH INDICATING THE POSSIBILITY OF FOG BEHIND THE DEPARTING RAIN BAND WITH THE POTENTIAL OF VISIBILITY REDUCTIONS TO LESS THAN ONE QUARTER MILE. THIS FOG HAS YET TO MATERIALIZE THUS FAR THIS MORNING...BUT CEILING HEIGHTS HAVE BEEN FALLING AND THE WIND WILL BEGIN TO DIE DOWN SOME ACROSS OUR WEST AFTER SUNRISE. THEREFORE...WILL CONTINUE TO INCLUDE POSSIBLE FOG IN OUR FORECAST FOR THIS MORNING. THERE HAS BEEN SOME DRIZZLE BEHIND THE RAIN BAND AND THIS IS ALSO LIKELY TO CONTINUE THROUGH AT LEAST A PORTION OF THE MORNING ESPECIALLY ACROSS EASTERN ZONES. THE DRIZZLE MAY EVEN LINGER OVER OUR FAR EAST THROUGH EARLY THIS AFTERNOON. MOST FORECAST MODELS BRING THE CLEARING LINE INTO KANSAS THIS AFTERNOON BUT KEEP MOST NEBRASKA ZONES SOCKED IN UNDER A LOW STRATUS DECK. THUS THERE WILL BE A TIGHT TEMPERATURE GRADIENT ALONG THE EDGE OF THIS STRATUS DECK...WHICH SHOULD BE LOCATED SOMEWHERE NEAR THE NEBRASKA KANSAS BORDER THIS AFTERNOON. TONIGHT...THE WET GROUND FROM THE RECENT RAIN ALONG WITH LIGHT AND VARIABLE WINDS WILL MAKE FOG POSSIBLE. THEREFORE...WILL CONTINUE TO CALL FOR AT LEAST THE POSSIBILITY OF SOME FOG LATE TONIGHT INTO EARLY MONDAY MORNING. MONDAY...THE NEXT UPPER TROUGH WILL BE DIGGING ACROSS THE WESTERN CONUS WITH AN ASSOCIATED SFC LOW DEVELOPING OVER EASTERN COLORADO. THE WIND WILL BE SOUTHERLY ACROSS THE PLAINS AHEAD OF THIS LOW AND WE SHOULD WARM UP NICELY WITH HIGH TEMPERATURES POTENTIALLY WELL ABOVE NORMAL. HOWEVER...THERE IS UNCERTAINTY IN THE LOW CLOUD FORECAST ON MONDAY...WHICH IF PRESENT...THESE LOW CLOUDS WOULD REALLY HAMPER OUR WARM UP. MONDAY NIGHT INTO TUESDAY...THE UPPER WAVE AND SFC LOW WILL PRESS THROUGH OUR FORECAST AREA WITH A COLD FRONT SWEEPING THROUGH. THIS IS A PROGRESSIVE FAST MOVING OPEN WAVE. THUS ANY DEFORMATION SNOW BAND WILL BE WEAK WITH LITTLE IF ANY SNOW ACCUMULATION. THE 00Z ECMWF AND 00Z GFS PLACE A BAND OF RAIN AND SNOW ACROSS OUR NORTHWEST ZONES MONDAY EVENING...WHICH SHOULD TURN OVER TO ALL SNOW AT SOME POINT AFTER MIDNIGHT. THIS BAND HEADS MORE NORTHEAST RATHER THAN SOUTHEAST...AND OUR SOUTHEAST ZONES MAY STAY COMPLETELY DRY. THE MOST AGGRESSIVE MODEL GENERALLY IS CALLING FOR ONE INCH OR LESS OF SNOW ACROSS OUR NORTHWEST...SO THIS IS NOT APPEARING TO BE A BIG DEAL FOR OUR AREA. TUESDAY WILL BE COOLER BEHIND THE COLD FRONT...BUT STILL ABOVE NORMAL AS THE COLDER AIR WILL TAKE SOME TIME TO SETTLE IN. LONG TERM...WEDNESDAY THROUGH SATURDAY. OVERALL NO MAJOR CHANGES TO THESE 4 DAYS FROM PREVIOUS FORECAST...ALTHOUGH A SLIGHT CHANCE OF SNOW HAS BEEN INTRODUCED FOR PARTS OF THE CWA THURSDAY...AND HIGH TEMPS FOR FRIDAY CONTINUE TO TREND UP A BIT. CONFIDENCE IS FAIRLY HIGH THAT THE MAJORITY OF THIS TIME FRAME IS PRECIPITATION FREE EXCEPT FOR MAYBE THURSDAY...WHICH ALSO LOOKS LIKE THE COLDEST DAY OF THE UPCOMING WEEK. STARTING OFF WEDNESDAY/WED NIGHT...00Z ECMWF/GFS RUNS ARE IN GOOD AGREEMENT ON THE BIG PICTURE. ALOFT DURING THE DAY...THE LOCAL AREA WILL SEE NORTHWEST FLOW BEHIND THE DEPARTURE OF A LARGE SCALE TROUGH AXIS THAT EXTENDS NORTH-SOUTH THROUGH THE HEART OF THE NATION...WITH THIS TROUGH AXIS PROGRESSING EAST TOWARD THE EASTERN MIDWEST/OHIO VALLEY REGION BY DAYS END. THEN ON WED NIGHT...A SHORTWAVE TROUGH DROPS SOUTHWARD OUT OF CANADA INTO THE DAKOTAS...REINFORCING THE TROUGHY PATTERN DOMINATING THE MAJORITY OF THE CONUS BY THIS TIME. CONFIDENCE IS FAIRLY HIGH IN A PRECIPITATION-FREE 24 HOURS HERE...AT LEAST OF THE MEASURABLE VARIETY...ALTHOUGH WOULD NOT BE SURPRISED TO SEE A FEW FLURRIES STILL BRUSHING EASTERN ZONES DURING THE DAY...AND THEN ANOTHER BATCH OF FLURRIES/LIGHT SNOW POSSIBLY APPROACHING NORTHERN/WESTERN COUNTIES LATE WEDNESDAY NIGHT...BUT BOTH OF THESE POSSIBILITIES SEEM LOW ENOUGH FOR NOW TO LEAVE OUT. TEMP-WISE...MADE VERY LITTLE IF ANY CHANGE TO PREVIOUS FORECAST...AS WEDNESDAY SHOULD BE ROUGHLY 10 DEGREES COOLER THAN TUESDAY IN THE WAKE OF THE FIRST OF TWO MID-WEEK COLD FRONTS. HIGHS ARE AIMED TO RANGE FROM MID-UPPER 20S FAR NORTHEAST...NEAR 30 TRI-CITIES...MID- UPPER 30S SOUTHWEST. THURSDAY/THURS NIGHT...HAVE INTRODUCED A SLIGHT CHANCE OF SNOW FOR ROUGHLY THE SOUTHWEST 1/3 OF THE CWA FOR THE DAYTIME HOURS...AND WOULD NOT BE SURPRISED TO SEE THIS SLIGHT CHANCE OF SNOW OR AT LEAST FLURRIES EXPANDED TO COVER MORE OF OUR AREA IN LATER FORECASTS IF TRENDS FROM THE 00Z ECMWF/GEM CONTINUE. IN SHORT...THIS LOOKS LIKE A FAVORABLE SETUP FOR A QUICK-HITTING MINOR SNOW ACCUMULATION...AS THE AFOREMENTIONED NORTHWEST-FLOW SHORTWAVE TROUGH THAT DROPS INTO THE DAKOTAS WED NIGHT CONTINUES TO SINK SOUTHEAST ACROSS EASTERN NEB/IA ON THURSDAY...AND A NORTH- SOUTH ORIENTED UPPER JET STREAK APPROACHES OUR LOCAL AREA FROM THE NORTHWEST...HELPING FOCUS A BAND OF MID LEVEL LIFT/SATURATION. NOT LOOKING LIKE HIGH-IMPACT BY ANY MEANS...BUT SOMETHING TO KEEP AN EYE ON. BY THURSDAY NIGHT...FORCING FOR ANY NUISANCE SNOW SHOULD HAVE MOVED OFF TO THE SOUTHEAST. IN THE LOW LEVELS...THE SECOND AND STRONGER COLD FRONT OF THE WEEK ENTERS THE CWA DURING THE DAY...ALTHOUGH THE CORE OF THE TRULY COLD AIR SHOULD REMAIN AT LEAST A FEW HUNDRED MILES TO OUR NORTHEAST...MUCH AS SEEN WITHIN THE PAST WEEK. CERTAINLY THIS WILL RESULT IN A SHARP AND HARD-TO- PIN-DOWN SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT FOR HIGHS ON THURSDAY...AND HAVE SHAVED A COUPLE DEGREES OFF PREVIOUS FORECAST ALL AREAS...AIMING FOR A RANGE FROM NEAR 20 FAR NORTHEAST...MID- UPPER 20S TRI-CITIES AND MID 30S SOUTHWEST. MUCH COLDER AIR WILL NOT BE FAR AWAY...WITH SINGLE DIGIT HIGHS POSSIBLY AS CLOSE AS FAR NORTHEAST NEB...SO WOULD NOT BE SURPRISED TO SEE THIS COLDER AIR PUSH SOUTHWEST INTO OUR AREA A BIT MORE AGGRESSIVELY THAN CURRENTLY ADVERTISED. FRIDAY/FRIDAY NIGHT...THE REGION REMAINS IN WEST-NORTHWEST FLOW ALOFT...AS A COUPLE SHORTWAVE TROUGHS PASS THROUGH THE FLOW...ONE STAYING WELL NORTH FROM CANADA INTO THE NORTHERN GREAT LAKES...AND THE OTHER SLIDING INTO OR JUST SOUTHWEST OF THE AREA. AT THIS TIME...NOTHING APPEARS STRONG ENOUGH TO GENERATE PRECIP FOR OUR CWA. THE BIGGER STORY IS A POTENTIALLY DECENT WARM-UP OVER THURSDAY...AS THE COLD LOW LEVEL RIDGE AXIS SLIDES EAST AND ALLOWS WARMER AIR TO INVADE THE CENTRAL PLAINS ON WESTERLY OR SOUTHERLY BREEZES. HAVE RAISED FRIDAY HIGHS 3-4 DEGREES FROM PREVIOUS FORECAST PER MULTI-MODEL ALLBLEND...NOW RANGING FROM MID 30S NORTHEAST TO LOW-MID 40S SOUTHWEST. SATURDAY CURRENTLY HAS RATHER HIGH CONFIDENCE OF BEING PRECIP-FREE...AND IS ALSO LOOKING LIKE THE WARMEST DAY SINCE MONDAY...AND MADE ALMOST NO CHANGE TO PREVIOUS HIGHS RANGING FROM MID 40S NORTHEAST TO UPPER 40S/LOW 50S SOUTH AND WEST. THE ECWMF SUGGESTS THERE COULD BE A DECENT NORTHWEST BREEZE AS THE REGION IS GLANCED BY A THE EDGES OF A WEAK COLD FRONT DRIVEN BY ANOTHER GREAT LAKES SHORTWAVE TROUGH...BUT EVEN SO DECENT MIXING AND A DOWNSLOPE WIND COMPONENT WOULD HELP AID A WARM-UP. && .GID WATCHES/WARNINGS/ADVISORIES... NE...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NEZ039>041-046>049- 060>064-072>077-082>086. KS...NONE. && $$ AVIATION...HALBLAUB 1144 UPDATE...HALBLAUB SHORT TERM...WESELY LONG TERM...PFANNCUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1130 AM CST SUN JAN 27 2013 .DISCUSSION... UPDATED GRIDS AGAIN...THIS TIME TO REMOVE POPS FROM AFTERNOON PERIOD IN ALL AREAS. LEFT A DRIZZLE MENTION UNDER LOW STRATUS...BUT AREAS OF PRECIPITATION HAVE MOVED AWAY TO THE EAST/NORTHEAST. MAYES && .AVIATION... 18Z TAFS FOR KOMA...KLNK...AND KOFK. CONDITIONS ARE LIKELY TO REMAIN BELOW MVFR THROUGH THE TAF CYCLE. LOW CIGS AND LOWERED VIS TODAY WILL PROBABLY IMPROVE JUST BRIEFLY THIS AFTERNOON. CIGS MAY ACTUALLY CLEAR OUT OF KOFK AND POSSIBLY KLNK...BUT WITH AMPLE LOW-LEVEL MOISTURE AND WINDS BECOMING LIGHT AND VARIABLE...FOG SHOULD BUILD IN SHORTLY AFTER MIDNIGHT AND LINGER THROUGH MUCH OF THE MORNING. KEPT FOG A LITTLE LIGHTER AND CIGS A LITTLE LOWER AND MORE OVERCAST AT KOMA AS THEY ARE NOT LIKELY TO SEE BREAKS IN THE CLOUDS THIS AFTERNOON THROUGH TONIGHT...BUT ALL SITES HAVE A RISK OF LOCKING DOWN AT 1/4SM FOR SEVERAL HOURS TONIGHT AND MONDAY MORNING. MAYES && .PREV DISCUSSION... /ISSUED 938 AM CST SUN JAN 27 2013/ DISCUSSION... HAVE MADE SEVERAL UPDATES TO THE GRIDS THIS MORNING TO REFLECT ONGOING WEATHER TRENDS. WITH SURFACE LOW AT 15Z CENTERED IN WESTERN KS/SOUTHEAST CO...DRY SLOT IS EDGING INTO SOUTHERN/SOUTHEAST NEB THIS MORNING. PRECIP IS JUST ABOUT OUT OF WESTERN IA...BUT SHOULD LINGER IN THE WRAPAROUND AREA IN NORTHEAST NEB INTO THE AFTERNOON. THE DRY SLOT HAS FILLED WITH LOW CIGS AND PATCHY FOG...BUT THINK THIS SHOULD IMPROVE THIS AFTERNOON. HAVE UPDATED CLOUDS TO BE EVEN MORE PESSIMISTIC...WHILE UPDATING WEATHER GRIDS TO REFLECT MORE DRIZZLE THAN RAIN AS SYSTEM EXITS /EXCEPT IN NORTHEAST NEB/. ALSO CUT MAX TEMP FORECAST IN THE SOUTHERN CWA...AS WARM NOSE AHEAD OF THE LOW IS BEING OFFSET BY CLOUDS. KEPT MENTION FOR AREAS OF FOG TONIGHT AS LOW-LEVEL MOISTURE MAY NOT SCOUR OUT UNDER WEAK LOW-LEVEL WINDS. MAYES PREV DISCUSSION... /ISSUED 233 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY. HERE COMES THE RAIN. SURFACE TEMPERATURES HAVE REMAINED ABOVE FREEZING THROUGH THE NIGHT AND WILL REMAIN THAT WAY THROUGH THE DAY...THUS NO THREAT FOR FREEZING RAIN IN OUR FORECAST AREA THIS MORNING. PRETTY SOLID BAND OF RAIN WILL CONTINUE TO PUSH TO THE NORTH THIS MORNING AND THROUGH MOST OF THE FORECAST AREA BY EARLY THIS AFTERNOON. A DEFINITIVE SOUTHERN EDGE WILL LIKELY EVEN CLEAR SOUTHEAST NEBRASKA BEFORE 6 AM BASED ON LATEST RAP HOURLY DATA. ONCE THE HEAVIER SHOWERS MOVE OUT...STRATUS WILL LIKELY PREVAIL FOR THE AFTERNOON WITH AREAS OF DRIZZLE MAINLY ALONG AND NORTH OF INTERSTATE 80...WHICH THEN PUSHES NORTHEAST OUT OF THE AREA THROUGH THE EVENING. THERE COULD BE SOME BRIEF CLEARING BEHIND THIS BY LATE EVENING. AT THAT POINT...BELIEVE WE WILL FOG BACK IN THROUGH DAYBREAK MONDAY...WITH THE LOW LEVEL MOISTURE NOT REALLY BEING SCRUBBED OUT. WINDS GO VERY LIGHT OR EVEN CALM IN MOST AREAS BY 09-12Z MONDAY...WITH BOTH MAV/MET GUIDANCE SUGGESTING WIDESPREAD FOG DEVELOPING...AND POSSIBLY DENSE IN MANY AREAS. THIS WOULD PROBABLY LINGER INTO EARLY MONDAY MORNING...AND WOULD NOT BE SURPRISED IF A DENSE FOG ADVISORY MAY EVENTUALLY BE NEEDED. OF SOME CONCERN WOULD BE SURFACE TEMPERATURES DROPPING TO NEAR OR BELOW FREEZING MONDAY MORNING ALONG AND NORTH OF I80...WHICH COULD RESULT IN SLICK ROADWAYS FOR THE MORNING COMMUTE. MONDAY IS A BIT OF A TRANSITION DAY WITH MUCH OF THE MID MISSOURI VALLEY IN BETWEEN SYSTEMS. THE SURFACE WARM FRONT MAY LIFT BACK TO THE NORTH TO NEAR I80 THROUGH THE DAY. MEANWHILE...THE NEXT TROUGH MOVING THROUGH THE NORTHERN ROCKIES SHOULD START TO SPREAD DEEPER MOISTURE INTO NORTHEAST NEBRASKA BY MONDAY AFTERNOON...BUT CERTAINLY MONDAY NIGHT. AT THE SAME TIME...AN ADVANCING COLD FRONT WILL ALSO BE USHERING IN COLDER AIR TO NORTHEAST NEBRASKA. SHOULD SEE RAIN MIX WITH AND CHANGE TO SNOW ACROSS NORTHEAST NEBRASKA...AND GIVEN THAT THIS IS OCCURRING AT NIGHT COULD PROBABLY EVEN SEEM SOME MINOR ACCUMULATIONS OF AN INCH UP THERE BY DAYBREAK TUESDAY. FURTHER SOUTH ALONG AND SOUTH OF I80...PRECIP POTENTIAL IS MORE MORE QUESTIONABLE...BUT WILL MAINTAIN SLIGHT CHANCE POPS THAT LINGER INTO TUESDAY AS WELL...BUT CERTAINLY COULD ALSO BE DRY ACROSS ALL AREAS BUT NORTHEAST NEBRASKA. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. A TRANSITION TO A COLDER ARCTIC AIR MASS WILL CONTINUE EARLY IN THE PERIOD WITH THE FIRST REINFORCING SHOT OF COLDER AIR OVERSPREADING THE AREA ON WEDNESDAY WITH BLUSTERY NORTHWEST WINDS. HIGHS WILL BE BACK IN THE UPPER TEENS NORTH TO UPPER 20S SOUTH...BUT COLDER FEELING WITH THE WINDS. THE GFS HAS HINTED AT SOME FLURRY POTENTIAL ACROSS NORTHEAST NEBRASKA AS H85 TEMPERATURES APPROACH THE DENDRITIC RANGE...BUT THE ECMWF IS STILL DRY. SECOND AND COLDER REINFORCING SURGE ARRIVES BY THURSDAY...AGAIN WITH CONTINUED NORTHWEST BLUSTERY CONDITIONS. EVEN COLDER TEMPS WELL WITHIN THE DENDRITIC RANGE WOULD SUGGEST SOME FLURRY POTENTIAL AGAIN WITH HIGHS EVEN COLDER IN THE LOWER TEENS NORTH TO MID 20S SOUTH...WITH WIND CHILLS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO ONCE AGAIN. SURFACE HIGH MOVES OVER THE AREA THURSDAY NIGHT RESULTING IN LOWS IN THE SINGLE DIGITS ONE MORE TIME. FRIDAY AND SATURDAY SHOULD BE TRANSITION DAYS BACK TO WARMER TEMPS AGAIN WEST WESTERLY FLOW...DRY CONDITIONS AND HIGHS BACK INTO THE MID TO UPPER 40S FOR THE WEEKEND. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1037 AM CST SUN JAN 27 2013 .1037 AM UPDATE... HAVE DROPPED OUR KS COUNTIES FROM THE ADVISORY SINCE VIS SATL SHOWS A PERIOD OF CLEARING. ANOTHER AREA OF STRATUS IS MOVING INTO PHILLIPS COUNTY AND WILL BE MOVING INTO ROOKS COUNTY WITHIN THE HOUR. UNSURE HOW THIS EVOLVES BUT IT COULD PUT A DAMPER ON OUR FCST HIGH TEMPS. AS WE MENTIONED YESTERDAY...THERE IS ROOM FOR CONSIDERABLE BUST POTENTIAL IN TEMPS NEAR THE BOUNDARY OF OVC VS CLR. IN COORDINATION WITH LBF...HAVE EXTENDED MENTION OF PATCHY FOG 12PM-3PM AS A BUFFER FROM THE WIDESPREAD DENSE FOG MENTION WHICH ENDS AT NOON. HAVE ALSO LOWERED HOURLY TEMPS N OF I-80 FOR THE NEXT 3 HRS. WE ARE SEEING BREAK IN THE OVC /BINOVC/ JUST NW OF BBW AND LBF. SO THIS SHOULD ALLOW FOR SOME INCREASE IN TEMPS AS THE DAY PROGRESSES. HAVE MADE SOME HOURLY ADJUSTMENTS TO SKY FCST THRU 00Z. ALL UPDATED PRODUCTS ARE OUT AND PUBLISHED TO THE WEB. && .PREV DISCUSSION... /ISSUED 847 AM CST SUN JAN 27 2013/ 846 AM UPDATE...VISIBILITIES CONTINUE TO DECAY. SO ISSUED A DENSE FOG ADVISORY UNTIL NOON. FOG WILL LINGER IN SOME AREAS PAST NOON...BUT VSBYS WILL IMPROVE TO MORE THAN A QUARTER MILE. NPW/ZFP ARE OUT. HWO/EHWO WILL POST SHORTLY. PREV DISCUSSION... /ISSUED 631 AM CST SUN JAN 27 2013/ AVIATION...12Z KGRI TAF. WILL STATE OFF THE TOP THAT THIS WILL BE A CHALLENGING 24 HOURS IN TERMS OF PINNING DOWN THE TIMING OF CEILING/VISIBILITY CHANGES...BUT THE BOTTOM LINE IS THAT A GOOD CHUNK OF THE PERIOD WILL SEE DEGRADED FLIGHT CATEGORIES RANGING BETWEEN LIFR AND MVFR. STARTING OFF RIGHT AWAY THIS MORNING...IFR/LIFR CONDITIONS ARE FIRMLY IN PLACE...AND THIS IS LIKELY TO PERSIST THROUGH MOST/ALL OF THE MORNING HOURS AS A SATURATED LOW LEVEL AIRMASS PERSISTS IN THE PRESENCE OF LIGHT SOUTHERLY BREEZES. WOULD NOT BE SURPRISED TO EVEN SEE A BRIEF PERIOD OF VLIFR CONDITIONS IN DENSE FOG. THIS AFTERNOON...ANTICIPATE VISIBILITY TO GRADUALLY IMPROVE INTO MVFR THEN VFR TERRITORY...WHILE CEILING TRENDS GRADUALLY IMPROVE TO LOW-END MVFR BY MID-LATE AFTERNOON. AS LOW LEVEL FLOW TURNS MORE WESTERLY LATE IN THE AFTERNOON/EARLY THIS EVENING ...HAVE REASONABLE CONFIDENCE THAT THERE SHOULD BE AT LEAST A 6 HOUR PERIOD OF VFR CONDITIONS AS THE LOW LEVEL CEILING FINALLY LIFTS/SCATTERS OUT. ATTENTION THEN TURNS TO THE LATE NIGHT HOURS...WHEN A LIGHT AND VARIABLE WIND REGIME ALONG WITH WET GROUND WILL LIKELY FOSTER THE REDEVELOPMENT OF FOG...ALTHOUGH TO WHAT EXTENT IS STILL UNKNOWN. FOR NOW...WILL ADVERTISE PREVAILING IFR CONDITIONS DURING THE LAST FEW HOURS OF THE PERIOD...AND DEFER TO LATER FORECASTS TO FINE TUNE THE DETAILS. PREV DISCUSSION... /ISSUED 449 AM CST SUN JAN 27 2013/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT. MOST OF THE MEASURABLE RAIN WILL HAVE EXITED OUR CWA TO THE NORTHEAST BY SUNRISE...BUT DRIZZLE AND FOG WILL STILL BE A FACTOR FOR SOME AREAS TODAY. THE TEMPERATURE FORECAST IS A BIG CHALLENGE...BUT EXPECT GENERALLY ABOVE NORMAL TEMPERATURES THROUGH TUESDAY. A SECOND STORM SYSTEM WILL ENTER OUR FORECAST AREA MONDAY NIGHT AND BRING WITH IT A CHALLENGING MIXED PRECIPITATION TYPE FORECAST. TODAY...THERE ARE NUMEROUS FORECAST CONCERNS CENTERED AROUND POSSIBLE FOG...A STRATUS DECK THAT WILL BE DIFFICULT TO SHAKE ESPECIALLY ACROSS NEBRASKA ZONES...A SHARP TEMPERATURE GRADIENT...AND EVEN SOME PATCHY DRIZZLE. THE SREF AND HRRR ARE BOTH INDICATING THE POSSIBILITY OF FOG BEHIND THE DEPARTING RAIN BAND WITH THE POTENTIAL OF VISIBILITY REDUCTIONS TO LESS THAN ONE QUARTER MILE. THIS FOG HAS YET TO MATERIALIZE THUS FAR THIS MORNING...BUT CEILING HEIGHTS HAVE BEEN FALLING AND THE WIND WILL BEGIN TO DIE DOWN SOME ACROSS OUR WEST AFTER SUNRISE. THEREFORE...WILL CONTINUE TO INCLUDE POSSIBLE FOG IN OUR FORECAST FOR THIS MORNING. THERE HAS BEEN SOME DRIZZLE BEHIND THE RAIN BAND AND THIS IS ALSO LIKELY TO CONTINUE THROUGH AT LEAST A PORTION OF THE MORNING ESPECIALLY ACROSS EASTERN ZONES. THE DRIZZLE MAY EVEN LINGER OVER OUR FAR EAST THROUGH EARLY THIS AFTERNOON. MOST FORECAST MODELS BRING THE CLEARING LINE INTO KANSAS THIS AFTERNOON BUT KEEP MOST NEBRASKA ZONES SOCKED IN UNDER A LOW STRATUS DECK. THUS THERE WILL BE A TIGHT TEMPERATURE GRADIENT ALONG THE EDGE OF THIS STRATUS DECK...WHICH SHOULD BE LOCATED SOMEWHERE NEAR THE NEBRASKA KANSAS BORDER THIS AFTERNOON. TONIGHT...THE WET GROUND FROM THE RECENT RAIN ALONG WITH LIGHT AND VARIABLE WINDS WILL MAKE FOG POSSIBLE. THEREFORE...WILL CONTINUE TO CALL FOR AT LEAST THE POSSIBILITY OF SOME FOG LATE TONIGHT INTO EARLY MONDAY MORNING. MONDAY...THE NEXT UPPER TROUGH WILL BE DIGGING ACROSS THE WESTERN CONUS WITH AN ASSOCIATED SFC LOW DEVELOPING OVER EASTERN COLORADO. THE WIND WILL BE SOUTHERLY ACROSS THE PLAINS AHEAD OF THIS LOW AND WE SHOULD WARM UP NICELY WITH HIGH TEMPERATURES POTENTIALLY WELL ABOVE NORMAL. HOWEVER...THERE IS UNCERTAINTY IN THE LOW CLOUD FORECAST ON MONDAY...WHICH IF PRESENT...THESE LOW CLOUDS WOULD REALLY HAMPER OUR WARM UP. MONDAY NIGHT INTO TUESDAY...THE UPPER WAVE AND SFC LOW WILL PRESS THROUGH OUR FORECAST AREA WITH A COLD FRONT SWEEPING THROUGH. THIS IS A PROGRESSIVE FAST MOVING OPEN WAVE. THUS ANY DEFORMATION SNOW BAND WILL BE WEAK WITH LITTLE IF ANY SNOW ACCUMULATION. THE 00Z ECMWF AND 00Z GFS PLACE A BAND OF RAIN AND SNOW ACROSS OUR NORTHWEST ZONES MONDAY EVENING...WHICH SHOULD TURN OVER TO ALL SNOW AT SOME POINT AFTER MIDNIGHT. THIS BAND HEADS MORE NORTHEAST RATHER THAN SOUTHEAST...AND OUR SOUTHEAST ZONES MAY STAY COMPLETELY DRY. THE MOST AGGRESSIVE MODEL GENERALLY IS CALLING FOR ONE INCH OR LESS OF SNOW ACROSS OUR NORTHWEST...SO THIS IS NOT APPEARING TO BE A BIG DEAL FOR OUR AREA. TUESDAY WILL BE COOLER BEHIND THE COLD FRONT...BUT STILL ABOVE NORMAL AS THE COLDER AIR WILL TAKE SOME TIME TO SETTLE IN. LONG TERM...WEDNESDAY THROUGH SATURDAY. OVERALL NO MAJOR CHANGES TO THESE 4 DAYS FROM PREVIOUS FORECAST...ALTHOUGH A SLIGHT CHANCE OF SNOW HAS BEEN INTRODUCED FOR PARTS OF THE CWA THURSDAY...AND HIGH TEMPS FOR FRIDAY CONTINUE TO TREND UP A BIT. CONFIDENCE IS FAIRLY HIGH THAT THE MAJORITY OF THIS TIME FRAME IS PRECIPITATION FREE EXCEPT FOR MAYBE THURSDAY...WHICH ALSO LOOKS LIKE THE COLDEST DAY OF THE UPCOMING WEEK. STARTING OFF WEDNESDAY/WED NIGHT...00Z ECMWF/GFS RUNS ARE IN GOOD AGREEMENT ON THE BIG PICTURE. ALOFT DURING THE DAY...THE LOCAL AREA WILL SEE NORTHWEST FLOW BEHIND THE DEPARTURE OF A LARGE SCALE TROUGH AXIS THAT EXTENDS NORTH-SOUTH THROUGH THE HEART OF THE NATION...WITH THIS TROUGH AXIS PROGRESSING EAST TOWARD THE EASTERN MIDWEST/OHIO VALLEY REGION BY DAYS END. THEN ON WED NIGHT...A SHORTWAVE TROUGH DROPS SOUTHWARD OUT OF CANADA INTO THE DAKOTAS...REINFORCING THE TROUGHY PATTERN DOMINATING THE MAJORITY OF THE CONUS BY THIS TIME. CONFIDENCE IS FAIRLY HIGH IN A PRECIPITATION-FREE 24 HOURS HERE...AT LEAST OF THE MEASURABLE VARIETY...ALTHOUGH WOULD NOT BE SURPRISED TO SEE A FEW FLURRIES STILL BRUSHING EASTERN ZONES DURING THE DAY...AND THEN ANOTHER BATCH OF FLURRIES/LIGHT SNOW POSSIBLY APPROACHING NORTHERN/WESTERN COUNTIES LATE WEDNESDAY NIGHT...BUT BOTH OF THESE POSSIBILITIES SEEM LOW ENOUGH FOR NOW TO LEAVE OUT. TEMP-WISE...MADE VERY LITTLE IF ANY CHANGE TO PREVIOUS FORECAST...AS WEDNESDAY SHOULD BE ROUGHLY 10 DEGREES COOLER THAN TUESDAY IN THE WAKE OF THE FIRST OF TWO MID-WEEK COLD FRONTS. HIGHS ARE AIMED TO RANGE FROM MID-UPPER 20S FAR NORTHEAST...NEAR 30 TRI-CITIES...MID- UPPER 30S SOUTHWEST. THURSDAY/THURS NIGHT...HAVE INTRODUCED A SLIGHT CHANCE OF SNOW FOR ROUGHLY THE SOUTHWEST 1/3 OF THE CWA FOR THE DAYTIME HOURS...AND WOULD NOT BE SURPRISED TO SEE THIS SLIGHT CHANCE OF SNOW OR AT LEAST FLURRIES EXPANDED TO COVER MORE OF OUR AREA IN LATER FORECASTS IF TRENDS FROM THE 00Z ECMWF/GEM CONTINUE. IN SHORT...THIS LOOKS LIKE A FAVORABLE SETUP FOR A QUICK-HITTING MINOR SNOW ACCUMULATION...AS THE AFOREMENTIONED NORTHWEST-FLOW SHORTWAVE TROUGH THAT DROPS INTO THE DAKOTAS WED NIGHT CONTINUES TO SINK SOUTHEAST ACROSS EASTERN NEB/IA ON THURSDAY...AND A NORTH- SOUTH ORIENTED UPPER JET STREAK APPROACHES OUR LOCAL AREA FROM THE NORTHWEST...HELPING FOCUS A BAND OF MID LEVEL LIFT/SATURATION. NOT LOOKING LIKE HIGH-IMPACT BY ANY MEANS...BUT SOMETHING TO KEEP AN EYE ON. BY THURSDAY NIGHT...FORCING FOR ANY NUISANCE SNOW SHOULD HAVE MOVED OFF TO THE SOUTHEAST. IN THE LOW LEVELS...THE SECOND AND STRONGER COLD FRONT OF THE WEEK ENTERS THE CWA DURING THE DAY...ALTHOUGH THE CORE OF THE TRULY COLD AIR SHOULD REMAIN AT LEAST A FEW HUNDRED MILES TO OUR NORTHEAST...MUCH AS SEEN WITHIN THE PAST WEEK. CERTAINLY THIS WILL RESULT IN A SHARP AND HARD-TO- PIN-DOWN SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT FOR HIGHS ON THURSDAY...AND HAVE SHAVED A COUPLE DEGREES OFF PREVIOUS FORECAST ALL AREAS...AIMING FOR A RANGE FROM NEAR 20 FAR NORTHEAST...MID- UPPER 20S TRI-CITIES AND MID 30S SOUTHWEST. MUCH COLDER AIR WILL NOT BE FAR AWAY...WITH SINGLE DIGIT HIGHS POSSIBLY AS CLOSE AS FAR NORTHEAST NEB...SO WOULD NOT BE SURPRISED TO SEE THIS COLDER AIR PUSH SOUTHWEST INTO OUR AREA A BIT MORE AGGRESSIVELY THAN CURRENTLY ADVERTISED. FRIDAY/FRIDAY NIGHT...THE REGION REMAINS IN WEST-NORTHWEST FLOW ALOFT...AS A COUPLE SHORTWAVE TROUGHS PASS THROUGH THE FLOW...ONE STAYING WELL NORTH FROM CANADA INTO THE NORTHERN GREAT LAKES...AND THE OTHER SLIDING INTO OR JUST SOUTHWEST OF THE AREA. AT THIS TIME...NOTHING APPEARS STRONG ENOUGH TO GENERATE PRECIP FOR OUR CWA. THE BIGGER STORY IS A POTENTIALLY DECENT WARM-UP OVER THURSDAY...AS THE COLD LOW LEVEL RIDGE AXIS SLIDES EAST AND ALLOWS WARMER AIR TO INVADE THE CENTRAL PLAINS ON WESTERLY OR SOUTHERLY BREEZES. HAVE RAISED FRIDAY HIGHS 3-4 DEGREES FROM PREVIOUS FORECAST PER MULTI-MODEL ALLBLEND...NOW RANGING FROM MID 30S NORTHEAST TO LOW-MID 40S SOUTHWEST. SATURDAY CURRENTLY HAS RATHER HIGH CONFIDENCE OF BEING PRECIP-FREE...AND IS ALSO LOOKING LIKE THE WARMEST DAY SINCE MONDAY...AND MADE ALMOST NO CHANGE TO PREVIOUS HIGHS RANGING FROM MID 40S NORTHEAST TO UPPER 40S/LOW 50S SOUTH AND WEST. THE ECWMF SUGGESTS THERE COULD BE A DECENT NORTHWEST BREEZE AS THE REGION IS GLANCED BY A THE EDGES OF A WEAK COLD FRONT DRIVEN BY ANOTHER GREAT LAKES SHORTWAVE TROUGH...BUT EVEN SO DECENT MIXING AND A DOWNSLOPE WIND COMPONENT WOULD HELP AID A WARM-UP. && .GID WATCHES/WARNINGS/ADVISORIES... NE...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NEZ039>041-046>049- 060>064-072>077-082>086. KS...NONE. && $$ UPDATE...HALBLAUB 1037 SHORT TERM...WESELY AVIATION...PFANNCUCH LONG TERM...PFANNCUCH