Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/22/13


AREA FORECAST DISCUSSION
NWS TUCSON AZ
845 PM MST THU MAR 21 2013 .SYNOPSIS...A WEATHER SYSTEM PASSING NORTHEAST OF THE AREA WILL BRING WINDY CONDITIONS TO SOME LOCATIONS FRIDAY AND SATURDAY. EXPECT A FEW DEGREES OF COOLING OVER THE WEEKEND. && .DISCUSSION...ANOTHER 12 HOURS OF DENSE SHEAVES OF MAINLY CIRRUS LEVEL CLOUD BEFORE CLEARING FROM THE WEST IN THE MORNING HOURS. 00Z NAM12 AND LATEST HRRR TRENDS SHOWING NO SURPRISES. GUSTY WINDS THE MAIN STORY WITH THE SYSTEM OVER THE NEXT 72 HOURS WITH ASSOCIATED FIRE WEATHER CONCERNS. PLEASE NOTE THAT THE CURRENT RED FLAG WARNING FOR FRIDAY AFTERNOON AND FIRE WEATHER WATCH FOR SATURDAY AFTERNOON DOES NOT INCLUDE EASTERN PIMA COUNTY. IT CURRENTLY INCLUDES ALMOST ALL OF COCHISE AND GRAHAM COUNTIES...AND APPROXIMATELY THE SOUTHERN HALF OF GREENLEE COUNTY. THE HAZARD MAP ON THE TWC WEBPAGE INCLUDES EASTERN PIMA AND SANTA CRUZ COUNTIES DUE TO THE SIZE AND SHAPE OF FIRE WEATHER ZONE 148 (THE 3 FIRE WEATHER ZONES CAN BE SEEN ON THE FIRE WEATHER FORECAST PAGE AT WWW.WRH.NOAA.GOV/FIREWX/?WFO=TWC). AS OF RIGHT NOW WE DON`T EXPECT WINDS TO BE QUITE STRONG ENOUGH IN MOST OF EASTERN PIMA AND SANTA CRUZ COUNTIES TO MERIT INCLUSION IN THE FIRE WEATHER HEADLINES. && .PREV DISCUSSION...THICK CIRRUS CLOUDS HAVE DOMINATED SOUTHERN ARIZONA SKIES TODAY ALTHOUGH SOME THINNING OR BREAKS HAVE OCCURRED NEAR THE INTERNATIONAL BORDER AND IN NORTHERN GRAHAM/GREENLEE COUNTIES. UPSTREAM CLOUDS WILL CONTINUE ACROSS THE REGION INTO THE NIGHT THEN THIN OUT FRIDAY MORNING IN MOST AREAS AS A UPPER TROUGH PASSING WELL TO OUR NORTH PULLS THEM OUT OF THE AREA. THAT SAME TROUGH WILL BRING ANOTHER SWATH OF CLOUDS ACROSS NRN AZ WHICH WILL JUST SKIRT THE WHITE MOUNTAINS FRIDAY AFTERNOON. THE COOLER AIR ALOFT COULD SQUEEZE OUT A STRAY SHOWER UP THERE. BIGGEST STORY WILL BE THE INCREASED WINDS FRIDAY AND SATURDAY TO THE SOUTH OF THE AFOREMENTIONED TROUGH PASSING BY. SOUTHERN ARIZONA WINDS MAY FALL JUST SHORT OF WIND ADVISORY LEVELS OF SUSTAINED AT 30 MPH...BUT SHOULD BE STRONG ENOUGH TO SURPASS CRITICAL FIRE WEATHER THRESHOLDS. SEE FIRE WEATHER DISCUSSION FOR DETAILS. WHILE COOLER AIR WILL BEGIN TO ENTER THE AREA FRIDAY...BECAUSE OF THE AMPLE SUNSHINE...TEMPERATURES SHOULD END UP SIMILAR TO TODAY...MAYBE EVEN A DEGREE OR TWO WARMER WHERE ZERO SUN OCCURS TODAY. 5-8 DEGREES OF COOLING IS EXPECTED FOR HIGH TEMPS THIS WEEKEND...WHICH WILL BE BACK TO NORMAL LEVELS. WE SHOULD WARM BACK UP AGAIN BY MIDWEEK AS WEAK HIGH PRESSURE RIDGING SETTLES IN...KD && .AVIATION...HIGH CLOUDS WILL CONTINUE THROUGH EARLY FRIDAY MORNING. WIND DIMINISHING TO LESS THEN 10 KTS THIS EVENING...THEN INCREASING AFTER 22/18Z BECOMING WESTERLY 15-25 KTS WITH GUSTS ABOVE 35 KTS E OF KTUS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...STRONGER WINDS ARE FORECAST FRIDAY AND SATURDAY WITH CRITICAL FIRE WEATHER CONDITIONS BEING FORECAST FOR MOST OF GRAHAM...COCHISE AND GREENLEE COUNTIES BELOW 7000 FEET. HAVE UPGRADED THE FIRE WEATHER WATCH ON FRIDAY TO A RED FLAG WARNING. THERE IS A SLIGHT CHANCE FOR LIGHT PRECIPITATION IN THE WHITES ON FRIDAY. GUSTY WINDS RETURN TO THE AREA SATURDAY AFTERNOON WITH CRITICAL FIRE WEATHER CONDITIONS BEING FORECAST FOR PRETTY MUCH IN THE SAME AREA FROM FRIDAYS EVENT INCLUDING FURTHER NORTH INTO NORTHERN GRAHAM AND GREENLEE COUNTIES. THE FIRE WEATHER WATCH IS STILL IN EFFECT FOR SATURDAY MAINLY EAST OF TUCSON. A LITTLE LESS WIND ON SUNDAY WITH A FEW AREAS IN FAR SOUTHEAST COCHISE COUNTY APPROACHING CRITICAL FIRE WEATHER CONDITIONS DURING THE AFTERNOON HOURS. WINDS RETURN TO NORMAL DIURNAL TRENDS MONDAY AND TUESDAY. CONFIDENCE IS LOW NEXT WEDNESDAY AND THURSDAY WITH RESPECTS TO POSSIBILITY OF CHANCES OF PRECIPITATION. && .TWC WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FRIDAY NOON TO 8 PM MST FOR EASTERN FIRE WEATHER ZONE AZZ148...INCLUDING MOST OF COCHISE AND GRAHAM COUNTIES AND SOUTHERN HALF OF GREENLEE COUNTY. FIRE WEATHER WATCH SATURDAY AFTERNOON AND EVENING FOR EASTERN FIRE WEATHER ZONE AZZ148 AND SOUTHERN 2/3RD OF FIRE WEATHER ZONE AZZ146...INCLUDING MOST OF COCHISE AND GRAHAM COUNTIES AND THE SOUTHERN 2/3RDS OF GREENLEE COUNTY. && $$ MEYER/DROZD/BROST VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1029 AM MDT WED MAR 20 2013 .UPDATE... && .SHORT TERM...CURRENT FORECASTS LOOK ON TRACK AT THIS TIME. MOISTURE TO SPREAD ACROSS MOUNTAINS THIS AFTERNOON ALONG WITH SOME MID LEVEL ASCENT. WITH LAPSE RATES AROUND 6 C/KM...SHOULD SEE SOME SNOW SHOWERS DEVELOP...BEST CHANCE FOR SHOWERS LATE THIS AFTERNOON OVER ZONE 31 AND THE REST OF THE MOUNTAINS TONIGHT WHEN THE LATEST RAP SHOWS THE BEST ASCENT MOVING OVERHEAD. FAVORED OROGRAPHICS IN WESTERLY FLOW...THOUGH SNOW AMOUNTS STILL APPEAR LESS THAN ADVISORY FOR ZONE 31 TONIGHT. ACROSS PLAINS...SOUTHERLY WINDS AND A BIT OF WARM AIR ADVECTION SHOULD DRIVE TEMPERATURES CLOSE TO 60 DEGREES. BUT LATEST WRF SYNTHETIC SATELLITE IMAGERY INDICATING SOME INCREASE IN MID AND HIGH LEVEL MOISTURE WHICH COULD HINDER WARMUP. MAY NEED TO SHAVE A FEW DEGREES OFF THE MAX TEMP GRIDS BUT WILL WAIT TO SEE WHAT DEVELOPS. PERHAPS A FEW SHOWERS THIS EVENING ALONG THE WYOMING AND NEBRASKA BORDERS AS SOME MID LEVEL ASCENT MOVES ACROSS WYOMING. .AVIATION...WEAK CONVERGENCE ZONE HAS DEVELOPED FROM NORTHEAST OF DIA TO NORTHERN ELBERT COUNTY...WITH WEAK WEST TO NORTHWEST WINDS AT KDEN...SOUTHWEST AT KAPA AND NORTHWEST AT KBJC. WINDS APPEARS THIS ZONE IS SLOWLY SHIFTING EAST...WOULD EXPECT WINDS AT KDEN TO BECOME A BIT MORE NORTHERLY BY 18Z...THEN NORTHEAST TO EAST DURING THE AFTERNOON. WILL TREND KAPA MORE SOUTHWEST THROUGH THE AFTERNOON...KEEPING LIGHT NORTHWEST WINDS AT KBJC. REST OF TAF TRENDS SEEM ON TRACK. LATEST RAP STILL INDICATING SOME SORT OF A WESTERLY BOUNDARY MOVING ACROSS THE DENVER AREA BETWEEN 21Z AND 00Z. THIS STILL SEEMS REASONABLE AS SOME MIXING COULD OCCUR BUT WILL LOWER SPEEDS A BIT. && .PREV DISCUSSION... /ISSUED 322 AM MDT WED MAR 20 2013/ SHORT TERM...THE FLOW ALOFT WILL BECOME MORE WLY TODAY AND TONIGHT AS MOISTURE GRADUALLY INCREASES IN THE MTNS BY LATER THIS AFTN AND EVENING. THERE IS VERY LITTLE MID LVL ASCENT WITH LAPSE RATES ON AVERAGE AROUND 6 C/KM. SHOULD SEE SNOW INCREASE IN ZN 31 LATE THIS AFTN AND ACROSS THE REST OF THE MTNS THIS EVENING. AMOUNTS THRU 12Z THU LOOK TO BE BLO ADVISORY CRITERIA EXCEPT POSSIBLY IN ZN 31. OVER NERN CO SURFACE HIGH PRES WILL MOVE INTO THE CNTRL US AS SFC LOW PRES DEVELOPS OVER ERN CO BY AFTN. THUS WILL SEE INCREASING SOUTH WINDS OVER THE PLAINS BY AFTN. ALTHOUGH THERE WILL BY AN INCREASE IN MID AND HIGH CLOUDS AT THIS TIME IT LOOKS DRY THRU THE AFTN HOURS. HIGHS THIS AFTN WILL RISE INTO THE UPPER 50S TO LOWER 60S OVER NERN CO EXCEPT POSSIBLE OVER THE FAR NERN CORNER WHERE READINGS WILL BE SLIGHTLY LOWER. FOR TONIGHT MAY SEE A SLIGHT CHC OF SHOWERS NR THE WY-NE BORDER SO WILL KEEP IN LOW POPHE TREND WOULD BE TO S IN THESE AREAS. LONG TERM...FOR THURSDAY...THERE WILL BE A FAST MOVING EMBEDDED WAVE IN THE NORTHWEST FLOW PATTERN. THIS WAVE WILL BENEFIT THE MOUNTAINS THE MOST WITH DECENT OROGRAPHIC FLOW AND STEEPENING LAPSE RATES BY THURSDAY AFTERNOON. THERE WILL STILL BE A CHANCE OF SHOWERS OVER THE NORTHEAST PLAINS...BUT DOWNSLOPE NORTHWEST WINDS WILL LIMIT SHOWER POTENTIAL OVER THE FRONT RANGE. BEST CHANCE WILL LIKELY BE FURTHER EAST AWAY FROM THE MOUNTAINS. SUBSIDENCE QUICKLY MOVES IN BEHIND THE WAVE THURSDAY EVENING WITH PRECIP ENDING AND CLEARING SKIES AND DECREASING WINDS. STILL SOME SNOW SHOWERS IN THE MOUNTAINS THURSDAY EVENING BEFORE LAPSE RATES STABILIZE AND MOISTURE BECOMES QUITE SHALLOW. ATTENTION THEN SHIFTS TOWARDS STRONGER STORM SYSTEM WHICH IS EXPECTED TO DEVELOP OVER THE NORTHERN GREAT BASIN ON FRIDAY BEFORE MOVING ACROSS COLORADO ON SATURDAY. YET AGAIN...LONG RANGE MODELS HAVE TRENDED BACK AWAY FROM THE CLOSED LOW SOLUTION TO A MORE PROGRESSIVE AND FASTER OPEN WAVE. THE GFS IS NOW THE FASTEST WHILE THE CANADIAN IS SLOWEST WHILE STILL HOLDING ON TO A CLOSED LOW NEAR THE 4 CORNERS BY MIDDAY SATURDAY. MOST OF THE GFS ENSEMBLE MEMBERS SUPPORT THE FASTER MOVING SOLUTION. REGARDLESS OF EXACT TRACK THERE STILL IS CERTAINLY THE POTENTIAL FOR IMPACT WINTER WEATHER ON SATURDAY IN THE REGION. NOT MUCH CHANGE TO ONGOING FORECAST BASED ON MODEL INCONSISTENCIES. FOR SUNDAY AND MONDAY...MAINLY DRY SUNDAY BUT ANOTHER WEAKER CLOSED LOW FEATURE OVER THE NORTHERN ROCKIES SLIDES A PIECE OF ENERGY INTO COLORADO LATE SUNDAY AND MONDAY FOR ANOTHER CHANCE OF SNOW OVER MUCH OF THE STATE. TEMPERATURES WILL BE BELOW NORMAL FOR MUCH OF THIS EXTENDED PERIOD. AVIATION...WINDS HAVE BECOME LIGHT SLY EARLY THIS MORNING. BOTH THE HRRR AND RAP SHOW WINDS BECOMING MORE ELY BY MIDDAY. BY LATE AFTN THERE ARE SOME INDICATIONS THE STRONGER WLY FLOW ALOFT WILL MIX DOWN TO THE SFC AS A BNDRY COMES OFF THE FOOTHILLS WITH WINDS BECOMING WLY IN THE 23Z-00Z TIMEFRAME AND CONTINUING THRU THE EARLY EVENING HOURS. BY MID EVENING WINDS SHOULD BECOME MORE SSW AND CONTINUE OVERNIGHT. VFR CONDITIONS WILL BE IN PLACE THRU THE PERIOD WITH ONLY SOME MID AND HIGH LVL CLOUD COVER THIS AFTN AND TONIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....ENTREKIN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
322 AM MDT WED MAR 20 2013 .SHORT TERM...THE FLOW ALOFT WILL BECOME MORE WLY TODAY AND TONIGHT AS MOISTURE GRADUALLY INCREASES IN THE MTNS BY LATER THIS AFTN AND EVENING. THERE IS VERY LITTLE MID LVL ASCENT WITH LAPSE RATES ON AVERAGE AROUND 6 C/KM. SHOULD SEE SNOW INCREASE IN ZN 31 LATE THIS AFTN AND ACROSS THE REST OF THE MTNS THIS EVENING. AMOUNTS THRU 12Z THU LOOK TO BE BLO ADVISORY CRITERIA EXCEPT POSSIBLY IN ZN 31. OVER NERN CO SURFACE HIGH PRES WILL MOVE INTO THE CNTRL US AS SFC LOW PRES DEVELOPS OVER ERN CO BY AFTN. THUS WILL SEE INCREASING SOUTH WINDS OVER THE PLAINS BY AFTN. ALTHOUGH THERE WILL BY AN INCREASE IN MID AND HIGH CLOUDS AT THIS TIME IT LOOKS DRY THRU THE AFTN HOURS. HIGHS THIS AFTN WILL RISE INTO THE UPPER 50S TO LOWER 60S OVER NERN CO EXCEPT POSSIBLE OVER THE FAR NERN CORNER WHERE READINGS WILL BE SLIGHTLY LOWER. FOR TONIGHT MAY SEE A SLIGHT CHC OF SHOWERS NR THE WY-NE BORDER SO WILL KEEP IN LOW POPHE TREND WOULD BE TO S IN THESE AREAS. .LONG TERM...FOR THURSDAY...THERE WILL BE A FAST MOVING EMBEDDED WAVE IN THE NORTHWEST FLOW PATTERN. THIS WAVE WILL BENEFIT THE MOUNTAINS THE MOST WITH DECENT OROGRAPHIC FLOW AND STEEPENING LAPSE RATES BY THURSDAY AFTERNOON. THERE WILL STILL BE A CHANCE OF SHOWERS OVER THE NORTHEAST PLAINS...BUT DOWNSLOPE NORTHWEST WINDS WILL LIMIT SHOWER POTENTIAL OVER THE FRONT RANGE. BEST CHANCE WILL LIKELY BE FURTHER EAST AWAY FROM THE MOUNTAINS. SUBSIDENCE QUICKLY MOVES IN BEHIND THE WAVE THURSDAY EVENING WITH PRECIP ENDING AND CLEARING SKIES AND DECREASING WINDS. STILL SOME SNOW SHOWERS IN THE MOUNTAINS THURSDAY EVENING BEFORE LAPSE RATES STABILIZE AND MOISTURE BECOMES QUITE SHALLOW. ATTENTION THEN SHIFTS TOWARDS STRONGER STORM SYSTEM WHICH IS EXPECTED TO DEVELOP OVER THE NORTHERN GREAT BASIN ON FRIDAY BEFORE MOVING ACROSS COLORADO ON SATURDAY. YET AGAIN...LONG RANGE MODELS HAVE TRENDED BACK AWAY FROM THE CLOSED LOW SOLUTION TO A MORE PROGRESSIVE AND FASTER OPEN WAVE. THE GFS IS NOW THE FASTEST WHILE THE CANADIAN IS SLOWEST WHILE STILL HOLDING ON TO A CLOSED LOW NEAR THE 4 CORNERS BY MIDDAY SATURDAY. MOST OF THE GFS ENSEMBLE MEMBERS SUPPORT THE FASTER MOVING SOLUTION. REGARDLESS OF EXACT TRACK THERE STILL IS CERTAINLY THE POTENTIAL FOR IMPACT WINTER WEATHER ON SATURDAY IN THE REGION. NOT MUCH CHANGE TO ONGOING FORECAST BASED ON MODEL INCONSISTENCIES. FOR SUNDAY AND MONDAY...MAINLY DRY SUNDAY BUT ANOTHER WEAKER CLOSED LOW FEATURE OVER THE NORTHERN ROCKIES SLIDES A PIECE OF ENERGY INTO COLORADO LATE SUNDAY AND MONDAY FOR ANOTHER CHANCE OF SNOW OVER MUCH OF THE STATE. TEMPERATURES WILL BE BELOW NORMAL FOR MUCH OF THIS EXTENDED PERIOD. && .AVIATION...WINDS HAVE BECOME LIGHT SLY EARLY THIS MORNING. BOTH THE HRRR AND RAP SHOW WINDS BECOMING MORE ELY BY MIDDAY. BY LATE AFTN THERE ARE SOME INDICATIONS THE STRONGER WLY FLOW ALOFT WILL MIX DOWN TO THE SFC AS A BNDRY COMES OFF THE FOOTHILLS WITH WINDS BECOMING WLY IN THE 23Z-00Z TIMEFRAME AND CONTINUING THRU THE EARLY EVENING HOURS. BY MID EVENING WINDS SHOULD BECOME MORE SSW AND CONTINUE OVERNIGHT. VFR CONDITIONS WILL BE IN PLACE THRU THE PERIOD WITH ONLY SOME MID AND HIGH LVL CLOUD COVER THIS AFTN AND TONIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RPK LONG TERM....ENTREKIN AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
909 AM EDT WED MAR 20 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM WELL TO OUR NORTH WILL TRACK INTO THE CANADIAN MARITIMES TODAY, WITH A COLD FRONT CROSSING OUR REGION LATE TODAY AND INTO TONIGHT. MEANWHILE, ANOTHER LOW PRESSURE SYSTEM WILL EMERGE OFF THE SOUTHEASTERN SEABOARD TONIGHT AND INTENSIFY AS IT TRACKS WELL OFF THE MID ATLANTIC COAST THROUGH THURSDAY. HIGH PRESSURE IS THEN FORECAST TO INFLUENCE OUR REGION FRIDAY THROUGH SUNDAY. FOR EARLY NEXT WEEK, A COASTAL LOW MAY AFFECT THE AREA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... BASED ON THE 12Z SOUNDING FULL SUN MACROS, WE BUMPED UP MAX TEMPERATURES SLIGHTLY. BASED ON THE LATEST HRRR AND ONGOING ECHOES, WE FILLED IN THE GAP OF FLURRIES IN THE POCONOS. OTHERWISE, THE REST OF THE FORECAST REMAINS CLOSE AND NO OTHER BIG CHANGES WERE MADE. AFTER A SUNNY BRISK START WITH WESTERLY WINDS GUSTING 25 TO 30 MPH THROUGH MID AFTERNOON...SKIES CLOUD UP RAPIDLY BETWEEN 6 AND 10000 FT VERY LATE IN THE AFTN (5PM IN RESPONSE TO FGEN AHEAD OF OUR FORMING COLD FRONT). WINDS BELOW 950 MB TURN SSW AND INCREASE ALONG THE DELMARVA WITH MOISTURE ADVECTION BY EVENING. TEMPS/WINDS ARE 50 50 BLENDED 00Z/20 NAM/GFS MOS GUIDANCE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... YOU`VE SEEN THE FAR TOO ROBUST NAM QPF FROM THE 06Z CYCLE... NEVERTHELESS THE MODEL IS CUING FOR WHAT I THINK SHOULD BE 2 NICE SNOW SHOWER BANDS. THE FIRST MAY BE TOO WARM TO SUPPORT MUCH SNOW ACCUM PRIOR TO 05Z EXPECT MAYBE CHESTER COUNTY. THE LATTER TWD 10Z MAY BE MORE PRODUCTIVE NEAR THE S OR CENTRAL NJ COAST. COULD BE AN INTERESTING HOUR OR TWO DURING THE NIGHT IN AN AXIS FROM KPHL TO KNEL OR SLIGHTLY FURTHER SOUTH. AXIS OF HIGH TT AND KI (MID 50S AND MID 20S RESPECTIVELY) REFLECTS FGEN MOISTENING A FAIRLY STEEP LOW LVL LAPSE RATE THAT SHOULD PRODUCE TWO NE-SW BANDS OF LIGHT TO MDT SNOW SHOWERS. WHILE THE INITIAL SNOWFALL SHOULD MELT ON CONTACT...I DO THINK THERE WILL BE AN ACCUMULATION. ITS SNOW SHOWERS...SO WHERE THE BANDS ARE MOST PRODUCTIVE IS NOT EASY TO BE SURE OF BUT THINK THAT MANY OF US FROM SE PA INTO NJ AND POSSIBLY N DE WILL AWAKE THURSDAY MORNING TO A FRESH COVER OF SNOW WITH POTENTIAL FOR ROAD TREATMENTS. TWO DAYS AGO...THIS LOOKED TO BE BEST FIT FOR THE HIGHER TERRAIN OF E PA BUT TRENDS HAVE BEEN SEWD AND SO...IT APPEARS TO ME THAT CENTRAL OR SNJ IS A BEST FIT FOR VARIABLE AMOUNTS OF 1/2 TO 1 INCH SNOW ON GRASS...POTENTIAL EXISTING FOR 2 INCH AMTS IN A COUPLE OF LOCATIONS. PAVEMENT LESS BUT PAVEMENT CAN BECOME SLIPPERY FM THIS LATER ON IF THE READ ON THE CONVECTIVE NATURE IS CORRECT. FCST TEMPERATURES/WINDS WERE A STRAIGHT 50 50 BLEND OF THE 00Z/20 NCEP MOS. FOR THIS TO BE A FAILED FCST LOOK FOR THE FUTURE 12Z/20 NAM AND GFS TO QUIT GENERATING PCPN FOR THIS COMING NIGHT. IF THE MODELED AMOUNTS ARE JUST .01 OR .03 THEN ITS NOT GOING TO BE MUCH IF ANYTHING AT ALL. BUT...IF THE MODEL AMTS CONTINUE TO ADVERTISE A 12 HOUR TOTAL OF .1 OR GREATER...THEN WE ARE IN BUSINESS. FOR THOSE WHO LOOK AT OTHER MODELS...MYSELF..I EXPERIENCE MORE SUCCESS USING THE NCEP MODELS IN QPF GENERATION FOR CONVECTIVE TYPE EVENTS. && .LONG TERM /THURSDAY THROUGH TUESDAY/... TO START THE LONG TERM, A WEAK LOW IS PROGGED TO BE NEAR THE MID ATLANTIC REGION, WITH MID-LEVEL TROUGHING BACK OVER THE APPALACHIANS. THIS WEAK LOW IS FORECAST TO MERGE WITH A MUCH STRONGER AREA OF LOW PRESSURE THAT WILL BE ADVANCING NORTHEASTWARD WELL OFF THE MID ATLANTIC COAST DURING THURSDAY. OVERALL MOISTURE AND LIFT ASSOCIATED WITH THE WEAK LOW NEAR THE MID ATLANTIC THURSDAY MORNING ARE NOT OVERLY IMPRESSIVE, BUT WE DID RETAIN SLIGHT CHANCE POPS FOR LIGHT RAIN/SNOW ACROSS MUCH OF THE REGION FOR A TIME. RELATIVELY QUIET WEATHER IS THEN EXPECTED FROM FRIDAY THROUGH SUNDAY AS HIGH PRESSURE FROM CENTRAL CANADA INFLUENCES OUR REGION. A RATHER COOL NORTHWEST FLOW ALOFT WITH A MID-LEVEL LOW REMAINING PRESENT TO OUR NORTH THROUGH THIS TIMEFRAME WILL KEEP CONDITIONS ON THE COOL SIDE WITH TEMPERATURES RUNNING BELOW MID TO LATE MARCH AVERAGES. GOING INTO EARLY NEXT WEEK, THE GFS AND ECMWF BOTH SHOW DEVELOPING LOW PRESSURE IN THE OHIO VALLEY. A SECONDARY COASTAL LOW IS ALSO FORECAST TO EMERGE OFF THE SOUTHEASTERN SEABOARD SUNDAY AFTERNOON AND SUBSEQUENTLY TRACK NORTHEAST NEAR THE MID ATLANTIC COAST SUNDAY NIGHT INTO MONDAY BEFORE MOVING OUT TO SEA MONDAY NIGHT. DIFFERENCES REMAIN AT THIS EXTENDED TIMEFRAME REGARDING THE TRACK AND INTENSITY OF THESE LOW PRESSURE SYSTEMS, WITH THE GFS GENERALLY SHOWING STRONGER SURFACE LOWS. THERMAL FIELDS ALSO DIFFER BETWEEN THE MODELS, AND THIS LOOKS TO BE ANOTHER MIXED RAIN/SNOW EVENT, WITH THE GREATEST CHANCES FOR MORE IN THE WAY OF FROZEN PRECIPITATION BEING ACROSS OUR NORTHWEST ZONES. OVERALL, THIS WILL BE THE NEXT POTENTIALLY SIGNIFICANT SYSTEM ON THE HORIZON TO WATCH, AND OVER THE NEXT FEW DAYS, THE DETAILS OF PRECIP TYPE AS WELL AS TIMING CAN BE IRONED OUT AS THE MODELS COME TO CLOSER AGREEMENT. && .AVIATION /13Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. AFTER 12Z...VFR WITH W GUSTS TO NEAR 25 KT. WINDS BACK LATE IN THE DAY AND DIMINISH WITH VFR CIGS FORMING BETWEEN 6000 AND 10000 FT NEAR 21Z. TONIGHT...CIGS LOWER TO 5000 FT MOST TAF LOCATIONS WITH A PERIOD OF MVFR OR IFR CONDS PROBABLE FOR KILG/KPHL/KPNE/KTTN/KACY/KMIV IN SNOW SHOWERS. BEST WINDOW OF OPPORTUNITY APPEARS TO BE AFTER 05Z. LIGHT WINDS BECOMING N 10-15 KTS BY MORNING. OUTLOOK... THURSDAY...POSSIBLE MVFR AND LEFTOVER LIGHT SNOW SHOWERS DURING THE MORNING, WITH IMPROVEMENT TO VFR FROM WEST TO EAST DURING THE AFTERNOON. FRIDAY THROUGH SATURDAY...MAINLY VFR CONDITIONS. SUNDAY...MAINLY VFR. CONDITIONS MAY BEGIN TO LOWER SUNDAY NIGHT WITH POSSIBLE RAIN/SNOW. && .MARINE... CONVERTED GALE TO SCA CONDS TODAY. COULD HAVE ISOLATED GALE GUST DURING MIDDAY BUT ITS NOT WORTH A GALE WARNING... JUST APPEARS TOO DIFFICULT TO ACHIEVE MULTIPLE HOUR GALE GUSTS TODAY AT ANY ONE LOCATION. TONIGHT...NO HEADLINE ANTICIPATED. WINDS EAST OF DE AND AND S NJ BECOME SSW G 20 KTS FOR A TIME WHILE ELSEWHERE WINDS SHOULD BECOME LIGHT. THEN ALL AREAS SHIFT TO THE N BY 8AM THURSDAY WITH G TO 20 KTS. THERE IS A SMALL CHANCE FOR G 25 KTS OFF THE DE WATERS NEAR 12Z THU. OUTLOOK... SCA CONDITIONS MAY BE POSSIBLE FOR A TIME ON THURSDAY WITH GUSTY WEST TO NORTHWEST WINDS AS AN INTENSIFYING LOW PRESSURE SYSTEM MOVES WELL OFF THE MID ATLANTIC COAST. FROM FRIDAY AND INTO THE WEEKEND, CONDITIONS ARE EXPECTED TO BE BELOW SCA CRITERIA AS HIGH PRESSURE INFLUENCES THE REGION. EARLY NEXT WEEK, A COASTAL LOW MAY AFFECT THE AREA WATERS. && .FIRE WEATHER... WE CONTACTED NJ FORESTRY AND NON 10 HR FUELS REMAIN TOO WET FOR THE RAPID SPREAD OF WILDFIRES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430- 431-450>455. && $$ SYNOPSIS...KLINE NEAR TERM...DRAG/GIGI SHORT TERM...DRAG LONG TERM...KLINE AVIATION...DRAG/KLINE MARINE...DRAG/KLINE FIRE WEATHER...GIGI
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
340 PM EDT WED MAR 20 2013 .SHORT TERM (TONIGHT-FRIDAY)... FOR THE REST OF THIS AFTERNOON...SHOWERS WITH A FEW THUNDERSTORMS SHOULD BE MOVING OVER THE AREA AS THE CONVECTION IN THE GULF KICKS OUT WITH THE NEXT UPPER DISTURBANCE. THE WEAK SURFACE LOW OVER THE PENINSULA SHOULD ALSO CONTINUE TO LIFT E/NE TO OVER THE ATLANTIC AND DRAG A COLD FRONT THROUGH THE AREA. THE SHOWERS AND THUNDERSTORMS SHOULD CLEAR QUICKLY OUT OF THE AREA AROUND 00Z...BUT HAVE KEPT 20 PERCENT CHANCES IN THROUGH 06Z AS ITS DEPENDENT ON HOW STRONG A PUSH THE NEXT BAND OF ENERGY HAS ONCE IT INTERACTS WITH THE CONVECTION THAT HAS BEEN STREAMING CLOUDS AND SOME STRATIFORM RAIN ACROSS THE AREA THROUGH THE DAY. WILL BE PUTTING A PRE-FIRST PERIOD INTO THE ZONES TO SHOW THE CONTINUING LATE AFTERNOON EXPECTED HIGH RAIN CHANCES. WINDS QUICKLY SHIFT AROUND TO THE SE FOR FRIDAY ALLOWING FOR SOME MOISTURE RETURN AS HIGH PRESSURE CONTINUES TO RIDGE ACROSS THE AREA. WITH THE MOISTURE RETURN HAVE ADDED AN AFTERNOON 20 PERCENT RAIN CHANCE. TEMPERATURES TONIGHT WILL BE IN THE LOWER 40S NORTH...AND IN THE UPPER 40S TO MID 50S ELSEWHERE. THURSDAY HIGHS WILL BE IN THE MID 60S NORTH AND COASTAL TO THE MID 70S SOUTH. THURSDAY NIGHT WILL FALL INTO THE MID 30S NORTH TO THE LOWER 40S TO LOWER 50S CENTRAL AND SOUTH. AND HIGHS FRIDAY WILL BE WARMING TO THE LOWER 70S NORTH TO THE LOWER 80S SOUTH. .LONG TERM (FRIDAY NIGHT-TUESDAY)... THE LONG TERM PERIOD BEGINS FRIDAY NIGHT WITH SURFACE HIGH PRESSURE OFF THE EAST COAST OF FLORIDA SLIDING FARTHER EAST. MEANWHILE A REMNANT FRONTAL BOUNDARY WILL MOVE BACK NORTH THROUGH FLORIDA AND THE EASTERN GULF AS A WARM FRONT BRINGS WINDS BACK AROUND TO THE SOUTH. A SHORTWAVE PASSING ALONG THE NORTHERN GULF COAST SATURDAY AND SATURDAY NIGHT WILL TAKE ADVANTAGE OF THE SURFACE BOUNDARY AND MOIST SOUTHERLY LOW LEVEL WINDS TO FUEL SHOWERS AND THUNDERSTORMS OVER THE NORTHERN HALF OF THE AREA. BEFORE RAIN CHANCES GET AN OPPORTUNITY TO SUBSIDE...A COLD FRONT ASSOCIATED WITH MID LEVEL TROUGHING WILL MOVE ACROSS THE AREA SUNDAY AND SUNDAY NIGHT WITH ANOTHER WAVE OF CHANCE POPS MOVING ACROSS THE ENTIRE AREA. THE FRONT WILL STALL OVER SOUTH FLORIDA WITH SLIGHT CHANCE (20 PERCENT) POPS LINGERING OVER SOUTHERN AND CENTRAL FLORIDA THROUGH THE EARLY PART OF THE WEEK. TEMPERATURES WILL GET A CHANCE TO WARM UP TO SEVERAL DEGREES ABOVE NORMAL THIS WEEKEND AHEAD OF THE COLD FRONT. MIN TEMPS WILL COOL OFF SOMEWHAT MONDAY NIGHT WITH LOWS IN THE MID TO UPPER 40S ALONG THE NATURE COAST...MID 50S OVER CENTRAL FLORIDA...AND AROUND 60 OVER SOUTHWEST FLORIDA. OVERALL...ECMWF IS A TOUCH FASTER THAN GFS THROUGH THE ENTIRE LONG TERM PERIOD ESPECIALLY WITH THE COLD FRONT LATE THIS WEEKEND. FOR THE POPS AND TEMPERATURES...WEIGHTED THIS FORECAST PACKAGE MORE TOWARDS GFS...BUT BLENDED IN THE ECMWF AS WELL TO STAY ON THE SAFE SIDE. && .AVIATION... TIMING OF RAIN AND STORMS CONTINUES TO BE A HUGE PROBLEM AS MODELS ARE STRUGGLING MIGHTILY WITH THE DETAILS OF TODAY`S FORECAST. TIMING OF MORE SIGNIFICANT PRECIP AND TSTMS ON THE 18Z TAFS WAS BASED PARTLY ON RADAR TRENDS THE HOUR BEFORE...BUT SINCE THEN...STORMS HAVE WEAKENED AND DECREASED IN COVERAGE ACROSS THE NEARSHORE WATERS. MORE AND MORE...IT APPEARS THE MAIN PRECIP/TSTM EVENT TODAY IS GOING OCCUR WITH THE LAST MAIN S/WV WHICH IS CURRENTLY GENERATING A SQUALL LINE SOUTH OF MOB. THIS LINE IS RACING ESE ACROSS THE GULF. WHAT IS LEFT OF THE LINE WILL IMPACT W AND SW FL ROUGHLY BETWEEN 22 AND 2Z WHICH IS THE TIME FRAME THE LATEST RAP IS HINTING AT AS WELL. BASED ON THIS WILL BE UPDATING THE TAFS TO MOVE BACK PRECIP TIMING MORE IN LINE WITH THIS THINKING. AFTER MVFR CONDITIONS ASSOC W/ THE SHRA AND TSTMS MOVES OUT OF THE AREA... EXPECT IMPROVING CONDITIONS OVERNIGHT WITH VFR CONDITIONS DEVELOPING AS COOL AND DRY AIR MOVES INTO THE REGION BEHIND A COLD FRONT. && .MARINE... WINDS AND SEAS ARE EXPECTED TO INCREASE TO SCA CONDITIONS ACROSS THE NORTHERN AND CENTRAL OFFSHORE WATERS BEHIND THE FRONT THIS EVENING AS HIGH PRESSURE BEGINS TO BUILD INTO THE AREA. HIGH PRESSURE THEN REMAINS ACROSS THE WATERS THROUGH SATURDAY NIGHT WITH WINDS DIMINISHING BY MID THURSDAY MORNING. THE NEXT COLD FRONT WILL THEN PUSH INTO THE AREA FOR SUNDAY WITH WINDS AND SEAS INCREASING AGAIN JUST AHEAD OF THE FRONT. && .FIRE WEATHER... COOLER AND DRIER AIR WILL BE MOVING INTO THE AREA BEHIND THE FRONT TONIGHT ALLOWING FOR SEVERAL HOURS OF CRITICAL HUMIDITIES THURSDAY AFTERNOON. WINDS SHOULD BE LIGHT AND ERCS LOW ENOUGH TO PREVENT ANY NEED FOR A RFW OR RFD. MOISTURE WILL BE RETURNING FRIDAY...BUT A FEW HOURS OF CRITICAL HUMIDITIES WILL STILL BE POSSIBLE. WILL CONTINUE TO MONITOR ERC VALUES BUT WINDS SHOULD BE LIGHT AGAIN. && .PRELIMINARY POINT TEMPS/POPS... TPA 50 67 48 75 / 20 0 0 20 FMY 56 74 52 81 / 20 0 0 20 GIF 50 71 48 78 / 20 0 0 20 SRQ 54 67 48 75 / 20 0 0 20 BKV 41 67 34 77 / 20 0 0 20 SPG 57 66 55 74 / 20 0 0 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 10 AM EDT THURSDAY FOR ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM. && $$ SHORT TERM/MARINE/FIRE WEATHER...24/COLSON LONG TERM/AVIATION...88/GITTINGER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
224 PM MDT WED MAR 20 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 224 PM MDT WED MAR 20 2013 19Z WATER VAPOR IMAGERY RUC ANALYSIS INDICATED SHORT WAVE RIDGE ACROSS NORTHERN PLAINS WITH STRONG TROUGH OVER THE PAC NW. AT THE SFC...TROUGH WAS DEEPENING OVER EASTERN COLORADO WITH STRONG SOUTH WINDS DEVELOPING ACROSS MUCH OF THE AREA. THICK CIRRUS HAS SLOWED WARMING DOWN CONSIDERABLY BUT THINK TEMPS WILL EVENTUALLY CLIMB INTO LOWER/MID 50S AS WINDS AID IN DEEP LAYER MIXING. TONIGHT...WEAK SHORT WAVE TROUGH WILL UNDERCUT H5 RIDGE TONIGHT AS STRONG WAA DEVELOPS TO THE NORTH OF DEVELOPING WARM FRONT ACROSS NORTHERN CWA. HAVE SOME CONCERNS THAT LIGHT PRECIP MAY CLIP THE NORTHEASTERN CWA IN AREA OF DEEP WAA...BUT VERTICAL PROFILES APPEAR TO STABLE TO PRODUCE PRECIPITATION RATES NEEDED TO SATURATE SUB CLOUD LAYER. PROBABILISTIC DATA SEEMS TO SUPPORT ANY PRECIP THREAT REMAINING NORTH OF AREA AS WELL SO PLAN ON CONTINUING DRY FORECAST. WILL HAVE TO WATCH UPSTREAM PRECIP POTENTIAL CLOSELY THOUGH AS WARM LAYER AOB 3C THROUGH MUCH OF THE NIGHT WHICH WOULD REMOVE ANY ICE FROM SOUNDING INITIALLY ALLOWING FOR RA/FZRA/IP TO FORM IF PRECIP WERE TO OCCUR. AS MENTIONED BEFORE THIS REMAINS A VERY LOW PROBABILITY AT THIS TIME AND IF PRECIP WERE TO OCCUR WET BULB PROCESSES WOULD COOL WARM LAYER QUICKLY RESULTING IN A FAIRLY SHORT DURATION. TOMORROW...A FEW AREAS OF MORNING FOG EXPECTED AS WINDS SHIFT TO THE EAST IN RESPONSE TO NEXT...MORE SIGNIFICANT SHORT WAVE TROUGH MOVING INTO THE NORTHERN ROCKIES. THINK WEATHER ACROSS CWA WILL BE FAIRLY QUIET THROUGH MUCH OF THE DAY...ALTHOUGH PRECIP THREAT WILL BEGIN TO INCREASE IN THE AFTERNOON AS LARGE SCALE FORCING FOR ASCENT INCREASES AND CAA ALOFT HELPS DESTABILIZE THINGS. DO NOT THINK STABILITY PROFILES SUPPORT A THUNDER THREAT ATTM AND PLAN ON KEEPING PRECIP TYPE AS RAIN THROUGH THE DAY. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 224 PM MDT WED MAR 20 2013 FIRST 500 MB SHORT WAVE WILL MOVE ACROSS THE HIGH PLAINS THURSDAY NIGHT...THOUGH BEST ENERGY IS PROGGED TO BE NORTH OF THE FORECAST AREA. INVERTED SURFACE TROUGH WILL PROVIDE LOW LEVEL CONVERGENCE FROM GOODLAND TO MCCOOK. HOWEVER...MODEL SOUNDINGS SHOW THAT THE AIR MASS WILL BE SLOW TO SATURATE BELOW 700 MB...ESPECIALLY OVER THE EASTERN PART OF THE FORECAST AREA. LAYER Q VECTOR CONVERGENCE IS ALSO NOT PARTICULARLY IMPRESSIVE...THOUGH LOW LEVEL FRONTOGENESIS IS A LITTLE BETTER FROM 00Z-06Z. BOTTOM LINE ON THIS FIRST WAVE...WILL CARRY POPS THROUGH 06Z WITH DECREASING CHANCES AFTERWARDS. MOST PRECIPITATION WILL BE IN THE FORM OF RAIN...THOUGH COLD AIR WILL EVENTUALLY ADVECT OVER THE AREA AFTER 06Z. AGAIN...THOUGH ...BEST DYNAMICS WILL BE EAST OF THE AREA BY THAT TIME...SO DO NOT EXPECT MUCH SNOW ACCUMULATION. THE FIRST SYSTEM WILL MOVE EAST FRIDAY...BUT THE NEXT MORE VIGOROUS WAVE WILL MOVE OVER EASTERN COLORADO BY FRIDAY AFTERNOON. THIS SYSTEM IS PROGGED TO HAVE EXCELLENT GEOSTROPHIC PARAMETERS THROUGH SATURDAY TO PRODUCE WIDESPREAD PRECIPITATION. THE BEST WINDOW FOR PRECIPITATION WILL OCCUR FROM 09Z SATURDAY THROUGH 03Z SUNDAY. BY 12Z SATURDAY...COLD AIR ADVECTION WILL BE OVER THE ENTIRE AREA...SO EXPECT PRECIPITATION TYPE TO BE ALL SNOW SATURDAY. PROJECTED SNOW TOTALS RANGE FROM TWO INCHES SOUTH TO SEVEN INCHES NORTH. THESE PROJECTIONS ARE IN LINE WITH WINTER SEASON ANALOGS AND WPC ESTIMATES. MODELS AND OTHER EXTERNAL GUIDANCE HAVE SHOWN DECENT RUN-TO-RUN CONSISTENCY WITH THIS SYSTEM. NORTH WINDS AT 20 TO 30 KNOTS WILL DEVELOP SATURDAY PRODUCING AREAS OF BLOWING SNOW. THE SYSTEM WILL MOVE EAST SUNDAY...BUT WILL KEEP SOME LOW POPS OVER THE EASTERN THIRD. YET ANOTHER SHORT WAVE TROUGH WILL MOVE OVER THE HIGH PLAINS SUNDAY NIGHT AND MONDAY BRINGING ANOTHER CHANCE OF PRECIPITATION. FOR TUESDAY AND WEDNESDAY...MODELS DIVERGE. FOR NOW... WILL KEEP THE FORECAST DRY. TEMPERATURES WILL BE SIGNIFICANTLY BELOW NORMAL FRIDAY THROUGH MONDAY GIVEN ABUNDANT CLOUD COVER...SNOW...AND THE AMOUNT OF COLD AIR WITH THE SYSTEM. MODELS SHOW WARMING TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1142 AM MDT WED MAR 20 2013 SOUTHERLY WINDS WILL INCREASE TO THE 16-22KT RANGE THROUGH THE AFTERNOON HOURS FIRST AT GLD AND THEN GRADUALLY EXPANDING TO THE EAST IMPACTING MCK TO SOME DEGREES AROUND 20Z. WEAK DISTURBANCE WILL MOVE OVER THE MCK AREA DURING THE EVENING HOURS...BUT CONFIDENCE IN PRECIPITATION DEVELOPING TOO LOW AT THIS POINT TO INCLUDE IN TERMINAL BUT GIVEN WARM +3C ALOFT THERE IS POTENTIAL FOR RA/FZRA SHOULD PRECIP DEVELOP. OTHERWISE WITH WINDS SHIFTING TO THE EAST AND LOW LEVEL ASCENT LINGERING THROUGH THE MORNING HOURS...POTENTIAL DOES EXIST FOR MORNING STRATUS AND FOG ALTHOUGH CURRENT CONFIDENCE LEVELS ARE LOW SO HAVE ONLY INCLUDED MINOR FLIGHT CATEGORY REDUCTIONS WHERE CONFIDENCE IS HIGHEST. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JRM LONG TERM...MENTZER AVIATION...JRM
AREA FORECAST DISCUSSION
NWS PADUCAH KY
850 PM CDT THU MAR 21 2013 .UPDATE... ISSUED AT 850 PM CDT THU MAR 21 2013 FORECAST APPEARS TO BE ON TRACK...WITH NO CHANGES MADE TO SNOWFALL AMOUNTS OR ADVISORY AREAS. A BUFFER ZONE OF CHANCE POPS WAS EXPANDED A COUPLE OF COUNTIES TO THE EAST FOR TONIGHT...MAINLY ALONG A KMDH TO KPAH TO KHOP LINE. THIS WAS BASED MAINLY ON RUC MODEL DATA. THE 21Z RUC WAS MORE AGGRESSIVE THAN PREVIOUS RUNS IN BRINGING THE DEEP MOISTURE /AS INDICATED BY 1000 TO 500 MB MEAN RH/ EASTWARD. RADAR TRENDS SUPPORT THE RUC MODEL. WHATEVER PRECIP MAKES IT INTO THE AREA OF CHANCE POPS WILL BE INSIGNIFICANT...SINCE THE MODELS DECREASE THE DEEP MOISTURE FROM NORTHWEST TO SOUTHEAST LATE TONIGHT. ALSO...SURFACE TEMPS WILL BE AT OR ABOVE FREEZING MUCH OF THE NIGHT WHERE PRECIP OCCURS. .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 259 PM CDT THU MAR 21 2013 NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY. THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES. A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT. ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW. THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT. USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO NEW MADRID. MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30 POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN. IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 259 PM CDT THU MAR 21 2013 THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES IMPACTING THE WFO PAH FORECAST AREA. THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF THE BETTER PERFORMING MODELS ON WEDNESDAY/. WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY /BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7 AM CDT/ SUNDAY MORNING. THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS. MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A 1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/ AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE. FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION. AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE. THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME OF YEAR. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1214 PM CDT THU MAR 21 2013 THE WINTER STORM SYSTEM TONIGHT IS NOT EXPECTED TO IMPACT ANY OF THE TERMINALS. SOME LOW VFR STRATO CU CEILINGS WILL CONTINUE FOR MUCH OF THE AFTERNOON IN THE NORTHEAST...ESPECIALLY AT KOWB. SURFACE HIGH PRESSURE OVER THE REGION WILL KEEP WINDS LIGHT THROUGH THE PERIOD. THE LONE EXCEPTION WILL BE AT KOWB EARLY THIS AFTERNOON WHEN A FEW GUSTS INTO THE TEENS WILL BE POSSIBLE. MID AND HIGH CLOUDS WILL OVERSPREAD KCGI AND KPAH QUICKLY THIS AFTERNOON...AND THEN WILL GRADUALLY LOWER THROUGH THE PERIOD. SOME GUIDANCE IS HINTING AT MVFR CEILINGS AT BOTH SITES 09Z-15Z FRIDAY...BUT CONFIDENCE IS TOO LOW TO MENTION AT THIS TIME. AS FOR PRECIPITATION...CANNOT RULE OUT A FEW FLURRIES THROUGH THE NIGHT AND INTO FRIDAY MORNING...BUT FORCING FOR ANY SIGNIFICANT PRECIPITATION IS HARD TO FIND. KEPT KCGI AND KPAH DRY AND VFR THROUGHOUT THE 18Z TAF PERIOD. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...WINTER WEATHER ADVISORY UNTIL 7 AM CDT FRIDAY FOR MOZ100-107>110-114. IN...NONE. KY...NONE. && $$ UPDATE...MY SHORT TERM...DRS LONG TERM...SMITH AVIATION...DRS
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
950 PM CDT THU MAR 21 2013 .DISCUSSION... WARM 60S OVER DEEP E TX AND LOW TO MID 40S ACROSS OUR NORTHERN COUNTIES WITH 50S IN A THIN BELT BETWEEN. THE FRONT LIES ACROSS NE TX AND TOLEDO BEND COUNTRY RUNNING EAST UNDER I-20. UNDER CUTTING IS GUIDANCE IS ONE THING BUT GETTING DOWN A FEW DEGREES BELOW CURRENT OBSERVATION WAS MORE THE PROCESS WITH THIS UPDATE. THE EASTERLY FLOW NORTH OF I-20 REMAINS CHILLED WITH 10 PLUS DEGREES SPREADS FOR MORE EVAPORATIVE COOLING AS WELL. HOPE A FEW DEGREES WORKS OUT. LITTLE CHANGE NEEDED ELSEWHERE WITH STILL SOUTHERLY GUSTS OVER OUR SOUTHERN TIERS AND THAT ENERGY IS RIDING OVER THE FRONTAL BOUNDARY. MOST OF THE RAIN SHIELD OVER ARKANSAS CONTINUES TO LIFT AWAY WITH SOME NEW DEVELOPMENT ALONG THE RED IN THE I-30 CORRIDOR. THIS TREND IS MODELED TO CONTINUE AMONGST MANY FROM THE NAM TO RAP TO GFS AND EURO. AND WE CERTAINLY DO NEED THE RAIN JUST ABOUT AREA WIDE WHILE THE GETTING IS GOOD...BUT THE NORTHERN HALF WILL FAIR WELL WITH HIGH POPS ALREADY OUT. /24/ && .AVIATION... VFR FLIGHT CONDITIONS TO DETERIORATE TO MVFR/IFR OVERNIGHT AS LOW LEVEL MOISTURE INCREASES. ALONG WITH RESTRICTED VISIBILITIES... SHOWERS AND ISOLATED THUNDERSTORMS TO INCREASE IN COVERAGE. LITTLE IMPROVEMENT EXPECTED ON FRIDAY. SURFACE WIND EAST TO SOUTHEAST AROUND 5 KNOTS OVERNIGHT TO BECOME SOUTH 5 TO 10 KNOTS AFTER DAYBREAK THEN SHIFT TO THE NORTHWEST AFTER 18Z. /05/ && .PREV DISCUSSION... /ISSUED 703 PM CDT THU MAR 21 2013/ DISCUSSION... JUST AN UPDATE TO THE ZONE FORECAST AND THE REC TO REMOVE THE LAKE WIND ADVISORY HEADLINES FROM TONIGHT. /24/ PREV DISCUSSION... /ISSUED 338 PM CDT THU MAR 21 2013/ DISCUSSION... A COMPLEX FCST CONTINUES TO UNFOLD IN THE NEAR TERM. A SHEAR AXIS/WARM FRONT IS NOTED FROM NEAR CLARKSVILLE TX...TO MINDEN LA...TO MONROE...SEPARATING A 10-15 DEGREE TEMP DIFFERENCE EITHER SIDE. THIS BOUNDARY HAS SERVED AS A FOCUS FOR SHOWERS TODAY AS IT HAS DRIFTED NEWD. SFC ANALYSIS SHOWS A LOW PRESSURE CENTER CURRENTLY OVER THE TX PANHANDLE...WHICH HAS TIGHTENED THE PRESSURE GRADIENT SUCH THAT GUSTY WINDS HAVE BEEN OBSERVED ACROSS MUCH OF TX. THE REGION IS UNDER DISTURBED WNW FLOW ALOFT...PER THE WV IMAGERY...WHICH IS PROVIDING JUST ENOUGH LIFT TO GENERATE SHOWERS AND ISOLD THUNDERSTORMS ACROSS MUCH OF ERN OK/WRN AR. THE SFC LOW IS FCST TO PUSH ESEWD TONIGHT THROUGH FRIDAY...BEFORE FILLING AND STALLING /ALONG WITH THE ASSOCIATED FRONTAL BOUNDARY/ OVER DEEP E TX...ALL THE WHILE KEEPING WIDESPREAD ELEVATED CONVECTION GOING MAINLY ALONG AND N OF I-20. THIS WOULD LEAVE PARTS OF THE REGION ALONG AND S OF I-20 IN THE WARM SECTOR FOR FRIDAY. WITH AMPLE VERTICAL WIND SHEAR AND MODERATE INSTABILITY IN PLACE...AT LEAST AN ISOLATED SEVERE THREAT APPEARS POSSIBLE. HOWEVER...THIS AREA IS FCST TO HAVE A SIGNIFICANT CAP IN PLACE...AND MODELS ARE NOT GENERATING MUCH IF ANY QPF. SO...THERE IS MUCH UNCERTAINTY TO SAY THE LEAST. AS WE MOVE INTO FRIDAY NIGHT/SATURDAY MORNING...ANOTHER SFC LOW IS FCST TO DEVELOP IN THE SRN PLAINS...AS THE MAIN UPPER DISTURBANCE MOVES ACROSS THE ROCKIES. THE UPPER TROF WILL PUSH THE SFC LOW EWD ALONG THE RED RIVER THROUGH SATURDAY...AS ANOTHER WAVE OF CONVECTION RAMPS UP ACROSS OUR REGION. THIS WILL LIKELY BRING A THREAT FOR SEVERE WEATHER PARTICULARLY IN THE WARM SECTOR S OF THE STALLED FRONTAL BOUNDARY. THE POSITION OF THE BOUNDARY IS STILL SOMEWHAT UNCERTAIN ATTM...BUT IS EXPECTED TO BE SOMEWHERE IN THE VICINITY OF I-20. UPPER LEVEL SUPPORT FOR THIS WAVE WILL BE QUITE A BIT STRONGER THAN ANY DISTURBANCES FRIDAY...AND THUS WILL CARRY A BETTER POTENTIAL TO PRODUCE STORMS CAPABLE OF DAMAGING WINDS AND HAIL. AS THE UPPER LOW PUSHES EWD SUNDAY...RAIN WILL COME TO AN END FROM W TO E SUNDAY MORNING THROUGH SUNDAY AFTERNOON...LEAVING THE REGION UNDER NEAR-ZONAL FLOW ALOFT. ANOTHER UPPER TROF IS FCST TO DIG SEWD ACROSS THE SRN PLAINS TUESDAY...BRINGING A DRY BACK-DOOR FRONT INTO THE REGION...WITH HIGH PRESSURE AT THE SFC TO BUILD IN AND NW FLOW ALOFT IN ITS WAKE. /12/ AVIATION... VFR FLIGHT CATEGORIES WILL CONTINUE THROUGH THE REMAINDER OF THE DAYLIGHT HOURS TODAY WITH OCCASIONAL CIGS BETWEEN 5 AND 9 KFT. AS LOW LEVEL MOISTURE INCREASES...EXPECT CIGS AND VISIBILITY TO GRADUALLY BECOME MVFR TONIGHT...ESPECIALLY IN AND AROUND SCATTERED TO NUMEROUS SHOWERS AND ISOLATED TSTMS. ALSO EXPECT PERIODS OF IFR CIGS AND VISIBILITY AS THE LOWER LEVELS BECOME SATURATED. ONLY SLOW IMPROVEMENT EXPECTED ON FRIDAY...WITH SOME IMPROVEMENT FROM WEST TO EAST AFTER 18Z. FREEZING LEVELS WILL RANGE FROM 6 KFT NORTH TO 11 KFT SOUTH...WITH ICING POSSIBLE ABOVE THESE LEVELS. MODERATE TURBULENCE EXPECTED VICINITY TSTMS. SURFACE WIND EAST TO SOUTHEAST... MOSTLY IN THE 10 TO 15 KT RANGE...WITH HIGHER GUSTS. /14/ && .PRELIMINARY POINT TEMPS/POPS... SHV 50 70 51 65 47 / 50 30 30 60 20 MLU 48 65 51 67 50 / 50 50 30 60 40 DEQ 39 55 42 56 40 / 70 40 30 60 30 TXK 42 59 45 59 42 / 70 50 30 60 30 ELD 41 58 45 61 43 / 70 50 30 60 40 TYR 60 73 51 65 43 / 30 30 30 50 20 GGG 54 71 52 65 46 / 40 30 30 50 20 LFK 59 79 59 73 46 / 20 30 30 50 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 24/05
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
934 PM EDT THU MAR 21 2013 .SYNOPSIS... LOW PRESSURE SLOWLY LIFTS NORTH INTO PENNSYLVANIA AS SURFACE HIGH PRESSURE BUILDS INTO THE MID-ATLANTIC THROUGH SATURDAY. STRONGER LOW PRESSURE WILL PUSH FROM THE OHIO VALLEY INTO THE AREA SUNDAY AND MONDAY. LOW PRESSURE WILL REMAIN IN PLACE THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... UPPER LOW OVER ERN CANADA REMAINS CUTOFF DUE TO AMPLIFIED DOWNSTREAM BLOCK PRESENT OVER THE NRN ATLANTIC AND A WEAK POLAR VORTEX. A NW TRAJECTORY AROUND THE LOW WILL CONTINUE TO KEEP THE MID-ATLANTIC REGION IN AN WINTER-LIKE PATTERN. WHENEVER HIGHS DURING THE DAY ARE ONLY NEAR NORMAL MIN TEMPS VALUES...THERE IS A GOOD BET FOR UNSEASONABLY COLD TEMPS AT NGT. WHILE WINDS WILL KEEP TEMPS FROM BOTTOMING OUT TNGT...MIN TEMPS IN THE 20S ARE EXPECTED CWA-WIDE /WHICH ARE ABOUT 10F BELOW NORMAL/. LAST FEW RUNS OF THE RAP APPEAR TO HAVE A GOOD HANDLE ON A SHORTWAVE TROUGH APPROACHING THE NRN MID-ATLANTIC STATES LATE THIS EVE AND ANOTHER LATE TNGT. ENHANCED LIFT AHEAD OF THESE DISTURBANCES MAY PRODUCE INTERMITTENT SNOW SHOWERS AND FLURRIES ALONG THE WRN SLOPES OF THE ALLEGHENY FRONT. SNOW ACCUMULATIONS SHOULD BE UNDER AN INCH TNGT. WINDS 10-20 MPH IN THE WESTERN MOUNTAINS WILL COMBINE WITH TEMPERATURES IN THE 20/S TO CREATE WIND CHILLS NEAR ZERO...QUITE FRIGID FOR THIS TIME OF YEAR. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... SURFACE HIGH PRESSURE PUSHES IN BEHIND THE NEXT WAVE TOMORROW. TOMORROW MAY BE A LOT LIKE TODAY WITH SLIGHTLY WARMER...THOUGH CONTINUED BELOW NORMAL TEMPERATURES IN THE 40S IN THE METRO AREAS. ANY SNOW FLURRIES / SHOWERS WILL END IN THE WESTERN MOUNTAINS BY EARLY AFTERNOON. COLD TEMPERATURES AND GUSTY WINDS WILL CONTINUE. AFTER ONE UPPER LOW FINALLY MOVES OFF THE NEW ENGLAND COAST THIS WEEKEND...ANOTHER WILL QUICKLY TAKE ITS PLACE - KEEPING THE REGION IN A CONTINUED COOL LATE SEASON PATTERN. THE TRANSITION PERIOD BETWEEN THESE TWO SYSTEMS WILL FEATURE ANOTHER MIX OF WINTRY PRECIP OVER THE AREA. SATURDAY WILL BE ANOTHER REPRIEVE FROM THE COOL/DRY AND BREEZY WX FROM THE LATER HALF OF THE CURRENT WEEK - BUT STILL BELOW AVG TEMPS. SKIES WILL LARGELY CLEAR OUT AND WINDS WILL DROP OFF TO A STIFF BREEZE ON SAT AFTN...W/ HIGHS BARELY REACHING 50 ACROSS THE SRN HALF OF THE AREA AND AT LEAST U40S OVER THE NRN HALF. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... FROM MIDDAY SUNDAY THRU LATE MON...WILL BE THE HIGHLIGHTED TIME FOR THE CWA TO RECEIVE PRECIP. THE SYSTEM WILL AGAIN BE ANOTHER COMPLEX DOUBLE SFC LOW SYSTEM...W/ THE SRN LOW PASSING WELL TO OUR SOUTH AND THE LOW MAINLY AFFECTING OUR AREA BEING THE OHIO VLY LOW. THE SYSTEM AS A WHOLE WILL BE BLOCKED TO THE NORTH BY AN UPPER VORT STATIONED OVER THE ST. LAWRENCE VLY...PREVENTING THE LOWS FROM RETREATING NEWD...SLOWING DOWN AND BECOMING MUCH MORE INFLUENCED BY THE WARMER COASTAL WATERS. INSTEAD...THIS WAVE OF PRECIP WILL BE MORE PROGRESSIVE MOVING WEST -> EAST AT A STEADIER PACE. THE IMPORTANT FACTOR FOR WINTRY PRECIP HOWEVER LIES IN THE SPATIAL DISTANCE BETWEEN THE TWO LOWS. THE FIRST LOW WILL MOVE OFF THE SRN ATLC COAST SUN AFTN...CARRYING A LARGE AREA OF PRECIP ACROSS THE CAROLINAS AND INTO THE MID ATLC. BY THE TIME OF BULK OF THE PRECIP SLIDES NWD INTO OUR AREA...TEMPS WILL BE WELL ABOVE FREEZING OUTSIDE OF THE HIGHER TERRAIN. NOW INTO LATE MARCH...THESE SYSTEMS THAT CONTAIN SNOW AS THEY DROP INTO LOWER LATITUDES WILL BE BATTLING THE NEAR-SFC CONDITIONS FOR ACCUMULATING SNOWS - OR EVEN STAYING SNOW WITHIN THE LOWEST FEW HUNDRED FT APPROACHING THE LOWLANDS/COASTAL AREAS. THE WRN HALF OF THE CWA WILL SEE THE BEST POTENTIAL FOR ACCUMULATING SNOW SUN NIGHT INTO EARLY MON...A MIX FROM THE SHEN VLY TO THE I-95 CORRIDOR AND MAINLY RAIN ALONG THE WRN/SRN SHORE COUNTIES OF MD ALONG THE BAY. TOTAL QPF FROM THIS SYSTEM RANGE FROM QUARTER-HALF INCH RANGE FOR MOST MED RANGE GUIDANCE...NOTHING SUBSTANTIALLY HIGHER OUTSIDE THE MTNS W/ ONLY SLIGHTLY HIGHER VALUES THEMSELVES. AS THIS SECONDARY LOW SHIFTS OFF THE COAST EARLY MONDAY...PLENTY NW FLOW STRAITED PRECIP BANDS WILL MOVE ACROSS THE AREA. THOUGH SFC TEMPS WILL LIKELY BE ABOVE FREEZING THROUGHOUT THE DAY...FALLING PRECIP WILL BE ALL SNOW FOR MUCH OF THE AREA - OUTSIDE THE BAY. ACCUMULATIONS WILL BE MINIMAL...IF ANY...FROM THE SHORT DURATION AND LOW EXPECTED QPF. GUSTY WINDS WILL CARRY THIS ACTIVITY OFF THE COAST INTO TUE...THEN DAILY PASSAGE OF WEAKER UPPER WAVES THAT WILL BASICALLY REINFORCE THE SAME TYPE OF WEATHER EACH DAY INTO THE COMING WEEK - HIGHS U40S/LOWS NEAR FREEZING - CLEAR AT NIGHT - MOSTLY CLOUDY DURING THE AFTN. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS TNGT AND FRI. WITH THE LOSS OF DAYTIME HEATING... HIGH BASED STRATOCU FIELD HAS JUST ABOUT DIMINISHED WHILE GUSTY NW WINDS HAVE SUBSIDED A BIT. STILL EXPECT NW WINDS 5-10 KT OVNGT WITH AN OCCASIONAL HIGHER GUST POSSIBLE. BREEZY NW WINDS CONTINUE FRI...ESPECIALLY DURING THE MRNG WHEN GUSTS 20-25 KT EXPECTED. NW SFC WINDS DECREASE BY AFTERNOON TO 5-15 KTS. QUIET SAT W/ SOLID VFR CONDS UNTIL MID MRNG SUN...WHEN CLOUDS INCREASE AND PRECIP ARRIVES FROM THE SW. THIS WILL MAINLY BE RAIN ACROSS THE REGION INTO SUN NIGHT...WHEN A PERIOD OF SNOW/RAIN MIX WILL BE POSSIBLE FROM THE SHEN VLY TO THE I-95 CORRIDOR. ANY SNOW ACCUM OUTSIDE THE MTNS SHOULD BE LIGHT...AND ALSO FALLING INTO AN ENVIRONMENT AT LEAST A COUPLE OF DEG ABOVE FREEZING. SOME LEFTOVER SNOW BANDS ON MON...BUT GUSTY WINDS AND HIGH-END MVFR CIGS THE MAIN CONCERN. THESE CLOUD DECKS AND BREEZY NW WINDS WILL RETURN NEARLY EACH DAY/AFTN FOR THE REMAINDER OF THE WEEK. && .MARINE... NWLY WINDS HAVE SUBSIDED A BIT AFTER SUNSET...BUT STILL REMAIN IN THE 15 TO 25 KT RANGE. SCA REMAINS IN EFFECT OVNGT ALTHOUGH A BRIEF LULL IN THE WINDS ARE POSSIBLE. GUSTY WINDS ARE EXPECTED AGAIN ON FRIDAY...AND SCA REMAINS IN PLACE. SCA CONDITIONS NEARLY EACH DAY FROM THE WEEKEND INTO THE MIDDLE OF NEXT WEEK...AND LIKELY BEYOND. EACH OF THESE WILL BE OF THE LOWER-END VARIETY BUT STILL BREEZY EACH AFTN AT LEAST. A LOW PRESSURE SYSTEM WILL SLIDE ACROSS THE REGION FROM LATE SUN THRU LATE MON. SOME BREEZY CONDITIONS AND MAINLY RAIN FOR THE COASTAL AREAS. DRY THRU REST OF THE WEEK...OUTSIDE OF A BRIEF SHOWER OR TWO BUT WINDS WILL DROP OFF AT NIGHT AND PICK UP BY THE NEXT AFTN. && .FIRE WEATHER... HUMIDITY WILL ONLY RECOVER TO 50-60% TONIGHT...AND WITH HIGH PRESSURE BUILDING IN AND A SHORT WAVE MOVING BY TOMORROW...LOCALLY ENHANCED THREATS OF WILDFIRE SPREAD ARE POSSIBLE FRIDAY. WINDS DO NOT APPEAR TO BE AS STRONG YESTERDAY AFTERNOON...COORDINATION WITH AREA FIRE MANAGERS EARLIER TODAY SUPPORTS THIS THREAT IS TOO LOCALIZED FOR THE ISSUANCE OF ANY STATEMENTS AT THIS TIME. SAT...MAINLY CLEAR SKIES AND RELATIVELY WARMER TEMPS - IN THE L50S. WINDS WILL BE LIGHTER THOUGH...AND EVEN W/ RH VALUES IN THE L30S THE HIGHER WIND GUSTS WILL BE ACROSS NRN MD WHERE THE HIGHER RH VALUES WILL BE LOCATED. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ530>543. && $$ UPDATE...KLEIN PREV DISC...SDG/GMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
146 AM EDT WED MAR 20 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 415 PM EDT TUE MAR 19 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP CLOSED LO CENTERED OVER ERN LK SUP DOWNSTREAM OF RDG ALONG THE W COAST. DEEP CYC NW FLOW OF COLD AIR ARND THE SFC LO NEAR WAWA ONTARIO IS DOMINATING THE CWA...CAUSING LES OVER MAINLY THE WRN ZNS EARLY THIS AFTN AS -16C H85 TEMPS SHOWN AT INL AT 12Z MOVE OVER THE LAKE. WITH SHARPENING PRES GRADIENT BTWN PRES RISE CENTER OVER NRN MN AND PRES FALLS OVER SE ONTARIO TO THE E OF THE SFC LO...THE NW WINDS ARE STRENGTHENING...WITH WIND GUSTS UP TO 40 MPH REPORTED CAUSING EXTENSIVE BLSN. THE SN HAS TAPERED OFF OVER THE FAR W AND SCENTRAL WITH THE ADVECTION OF DRIER AIR OBSVD IN MN AT 12Z/WELL DEPICTED ON THE 12Z MPX RAOB AND DOWNSLOPE FLOW INTO THE SCENTRAL. PUBLIC REPORTS INDICATE AS MUCH AS 18 INCHES OF SN HAS FALLEN OVER THE HIER TERRAIN OF THE W. FARTHER UPSTREAM...ANOTHER SHRTWV IS DIGGING SEWD THRU LK WINNIPEG. MAIN FCST CONCERNS THRU WED REMAIN LES/WIND TRENDS AND GOING HEADLINES AS CLOSED LO DRIFTS ONLY SLOWLY TO THE ENE THRU SE CANADA. LATE TODAY/TNGT...OVERALL DEEP CYC NW FLOW ARND SLOWLY DEPARTING LO IS PROGGED TO LINGER AND CAUSE PERSISTENT LES IN THE NW WIND SN BELTS. THE LES INTENSITY OVER THE FAR W...ESPECIALLY WHERE THE FETCH ACRS THE OPEN WATER IS SHORTER NEAR IWD...HAS DIMINISHED AS DRIER AIR IN MN SLID EWD. THIS DRY AIR WL IMPACT MAINLY THE AREAS NEAR THE WI BORDER. SO THE SCENTRAL SHOULD REMAIN DRY WITH DOWNSLOPING DRIER FLOW. BUT LATER TNGT...SHRTWV NOW NEAR LK WINNIPEG IS FCST TO DIG SEWD...CAUSING THE LLVL FLOW TO VEER A BIT AND BRING BACK A RETURN OF DEEPER MSTR OVER THE ENTIRE CWA ON THE CYC SIDE OF ITS TRACK. THESE TRENDS SHOULD CAUSE LES TO PICK UP AGAIN AT IWD FOLLOWING A BREAK THIS EVNG. IN THE NW WIND SN BELTS E OF MQT...THE ARRIVAL OF COLDER AIR WL LIKELY ENHANCE THE INTENSITY OF THE LES THRU THE NGT WITH FVRBL WNW LLVL FLOW SHIFTING NW. ANOTHER FACTOR FAVORING HEAVY SN IS FVRBL ALIGNMENT OF FCST UVV MAX WITHIN THE DGZ EVEN IF STRONG WINDS THAT CAUSE A BREAK UP OF THE DENDRITES ACT TO REDUCE THE SN/WATER RATIOS A BIT. BUT THESE STRONG WINDS WL CAUSE EXTENSIVE BLSN/REDUCED VSBY ESPECIALLY NEAR LK SUP...EVEN WHEN THE LES IS NOT FALLING HEAVILY. WED...AS THE CLOSED LO SLOWLY DRIFTS TO THE E...CYC NW FLOW IS PROGGED TO VEER SLOWLY TO THE NNW. WITH THE ARRIVAL OF SOMEWHAT WARMER ATLANTIC AIR FM THE NE ARND INTENSE LO PER THE 12Z GFS AND ESPECIALLY THE NAM...DEEP MSTR IS FCST TO LINGER. ALTHOUGH THE WARMING WITH H85 TEMPS PROGGED TO RISE TOWARD -10C OVER FAR ERN LK SUP MIGHT TEND TO REDUCE LES INTENSITY...THE ARRIVAL OF SOME LARGER SCALE QVECTOR CNVGC/MAINTENANCE OF DEEPER MSTR ASSOCIATED SOME ISENTROPIC ASCENT WL RETAIN A LK ENHANCED COMPONENT. ALTHOUGH THE BEST CHC FOR CONTINUED DRY WX WL BE OVER THE SCENTRL...FCST SDNGS INDICATE THE MSTR WL BE DEEP ENUF TO SUPPORT AT LEAST SCT -SHSN. SOME OF THE GUIDANCE SUGGESTS SOME DRIER AIR MAY ARRIVE OVER THE W ON WED AFTN... BUT SLOW MOTION OF THE CLOSED LO TO THE E FAVORS THE MODELS THAT SHOW A SLOWER EWD PROGRESSION OF THIS DRYING. GOING HEADLINES LOOK TO BE IN GOOD SHAPE AS LONG DURATION EVENT WL ADD TO SN ACCUMS THAT HAVE ALREADY HIT WARNING TOTALS IN MOST AREAS WHERE THESE HEADLINES HAVE BEEN IN EFFECT. EXPECT STORM TOTAL SN TO REACH 24 INCHES OR MORE OVER THE HIER TERRAIN OF THE W. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 415 PM EDT TUE MAR 19 2013 LOOK FOR A SLOW AND STEADY RISE IN TEMPERATURES THROUGH THE PERIOD AS WE SLOWLY LOSE THE INFLUENCE OF THE NEARBY 500MB TROUGH. THE ELONGATED 500MB TROUGH WILL EXTEND FROM JUST NE OF MAINE TO LOWER MI...AND SOUTHERN UPPER PORTIONS OF UPPER MI AT 00Z THURSDAY...WITH A SIZABLE RIDGE STRETCHING ACROSS WYOMING AND THE WESTERN DAKOTAS UP THROUGH SASKATCHEWAN. WHILE THE 500MB RIDGE WILL PUSH INTO WESTERN UPPER MI/LAKE SUPERIOR FRIDAY...IT WILL TAKE UNTIL FRIDAY NIGHT UNTIL THE NEARLY STEADY STATE LOW OVER THE EAST PUSHES OFFSHORE. THE 19/00Z RUNS OF THE ECMWF AND CANADIAN HOLD ONTO THE TROUGH ACROSS EASTERN UPPER MI A BIT LONGER THAN THE GFS /BY ROUGHLY 6HRS/. THE SFC TROUGH WILL LIKELY LINGER ACROSS EASTERN MICHIGAN THROUGH 12Z FRIDAY. THE RESULT WILL BE CONTINUED LAKE EFFECT SNOW SHOWERS FOR NORTHERLY-NNW WIND FAVORED LOCATIONS NEAR LAKE SUPERIOR. 850MB TEMPS WILL MODERATE FROM THE -12 TO -15C AT 00Z THURSDAY TO AROUND -8C BY DAYBREAK FRIDAY. EXPECT QUICKLY DIMINISHING LAKE EFFECT SNOW SHOWERS AFTER THURSDAY AFTERNOON...WITH LOWERING INVERSION HEIGHTS 500MB RIDGING WILL BE THE RULE FRIDAY NIGHT THROUGH AT LEAST SATURDAY NIGHT. LOOK FOR A CLUSTERED AREA OF LOW PRESSURE CENTERED NEAR MONTANA AT 00Z SATURDAY WILL DIVIDE FRIDAY NIGHT...WITH THE NORTHERN LOW SPINNING IN PLACE...AND THE SOUTHERN EXTENT OF THE TROUGH DIVING ACROSS TEXAS AND OKLAHOMA BY LATE SATURDAY AFTERNOON/SATURDAY NIGHT. THE 00Z RUNS OF THE GFS AND ECMWF WERE FAIRLY CONSISTENT WITH THE TRACK OF THE SOUTHERN TROUGH...MOVING IT OVER KENTUCKY AND WEST VIRGINIA BY DAYBREAK MONDAY...WITH THE RIDGE WEAKENING BUT STILL REMAINING OVER LAKE SUPERIOR AND UPPER MICHIGAN THROUGH AT LEAST SUNDAY NIGHT. THE 12Z GFS CAME IN WITH THE 500MB LOW SHIFTED APPROX 250MI TO THE NORTHWEST OF THE 00Z RUN TRACK...WHICH WOULD BRING IT ACROSS LOWER MI AT 00Z TUESDAY. THIS WOULD RESULT IN STRONGER WINDS FOR CENTRAL AND EASTERN AREAS...AS WELL AS UPSLOPE LES NORTH CENTRAL WITH SYNOPTIC SNOW HUGGING THE EASTERN COUNTIES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 140 AM EDT WED MAR 20 2013 WITH A COLD CYCLONIC NW FLOW CONTINUING AROUND LOW PRES DEPARTING SLOWLY THROUGH NORTHERN ONTARIO THIS FCST PERIOD...EXPECT SHSN TO IMPACT CMX/IWD...WITH IFR/LIFR CONDITIONS PREDOMINATING. THE WORST CONDITIONS TO VLIFR ARE MOST LIKELY AT THE MORE EXPOSED CMX LOCATION WITH DEEPER MOISTURE AND STRONGER WINDS. AT SAW...DOWNSLOPING NW WINDS SHOULD RESULT IN MAINLY MVFR CONDITIONS THRU THE FCST PERIOD. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 415 PM EDT TUE MAR 19 2013 EXPECT NW GALES/HEAVY FREEZING SPRAY TO LINGER THRU AT LEAST WED MORNING AS DEEP LO PRES OVER SE ONTARIO EDGES SLOWLY TO THE E AND A COLD...GUSTY NW WIND CONTINUES. WINDS/FREEZING SPRAY ARE LIKELY TO DIMINISH OVER THE W WED AFTERNOON FARTHER FROM THE SLOWLY RETREATING LO. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR MIZ001>004-009-084. WINTER STORM WARNING UNTIL 8 AM EDT THURSDAY FOR MIZ006-007-085. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR LSZ162-240>245-248>251-263>267. GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ THIS AFTERNOON FOR LSZ162- 243>245-249>251-263>267. GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR LSZ248. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...JLB MARINE...KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
732 PM CDT THU MAR 21 2013 .AVIATION.../00Z TAF ISSUANCE/ VFR CONDITIONS WILL BE FOUND ACROSS THE REGION DURING THE EVENING...ALTHOUGH SOME IFR/LIFR CIGS/VSBYS WILL BE POSSIBLE IN SPOTS AS THE NIGHT WEARS ON DUE TO SOME FOG. CONDITIONS WILL IMPROVE TO VFR AGAIN ON FRIDAY. && .PREV DISCUSSION... /ISSUED 308 PM CDT THU MAR 21 2013/ SHORT TERM.../NOW - FRIDAY/ AT 3PM/2000Z...THERE WAS A RIDGE OF HIGH PRESSURE OVER THE NORTHERN PLAINS AND SOUTHERN MINNESOTA. THE NORTHLAND HAD LIGHT NW WINDS DUE TO A LARGE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN UNITED STATES AND SOUTHEASTERN CANADA. MOST OF THE NORTHLAND HAD SUNNY TO MOSTLY SUNNY SKIES...BUT THERE WAS STILL SOME LINGERING LAKE EFFECT SNOW RELATED OVC CLOUDS OVER THE FAR EASTERN FORECAST AREA IN NW WISCONSIN. THE OVC CLOUDS WERE QUICKLY DIMINISHING AS THE WINDS WEAKENED OVER WESTERN LAKE SUPERIOR...CUTTING OFF THE MOISTURE SUPPLY. TEMPERATURES WERE IN THE LOWER TO UPPER 20S ACROSS THE NORTHLAND. TONIGHT...THE HIGH PRESSURE IN THE NORTHERN PLAINS WILL SLOWLY MOVE INTO THE NORTHLAND. THE NORTHLAND CAN EXPECT CLEAR TO MOSTLY CLEAR SKIES. THERE COULD BE SOME CLOUDS OVER THE TIP OF THE ARROWHEAD LATE TONIGHT. THE NAM AND RAP INDICATE SOME ENHANCED LOW LEVEL MOISTURE MOVING INTO THAT AREA...BUT LEANED ON A CLEAR FORECAST. THE MODEL GUIDANCE IS LIKELY MUCH TOO WARM CONSIDERING THE CLEAR SKIES AND VERY LIGHT WINDS EXPECTED FOR TONIGHT...SO UNDERCUT THE MODEL CONSENSUS BY SEVERAL DEGREES. OVERNIGHT LOWS WILL PROBABLY BE WELL INTO THE SINGLE DIGITS BELOW ZERO ACROSS MOST OF THE NORTHLAND. FRIDAY...THE HIGH PRESSURE OVER THE NORTHLAND WILL PROMOTE SUNNY TO MOSTLY SUNNY SKIES FOR AT LEAST THE MORNING. THERE COULD BE SOME INCREASING CLOUD COVER IN THE AFTERNOON BASED ON MODEL RH. HOWEVER...LEANED ON LESS CLOUD COVER SINCE THE MODELS SEEM TO BE EXAGGERATING THE POTENTIAL FOR CLOUD COVER. FRIDAY COULD VERY EASILY BE SUNNY ACROSS THE REGION...SO UPDATES MIGHT NEED TO BE MADE IN THE FUTURE. HIGH TEMPERATURES WILL LIKELY BE IN THE LOWER 30S. LONG TERM.../FRIDAY NIGHT - WEDNESDAY NIGHT/ CONTINUED QUIET WEATHER CONDITIONS THROUGH THE WEEKEND AND INTO THE MIDDLE OF NEXT WEEK WITH A NARROW RIDGE OF HIGH PRESSURE SITUATED OVER THE UPPER MIDWEST BETWEEN TWO SLOW MOVING UPPER LOWS. THE LOW TO THE WEST WILL EVENTUALLY UNDERCUT THE HIGH PRESSURE BY THIS WEEKEND. HOWEVER...THE ACTIVE PATTERN WILL REMAIN WELL TO THE SOUTH AND LEAVE THE NORTHLAND MOSTLY DEVOID OF PRECIPITATION. THE LOW LEVEL FLOW WILL BE FAVORABLE FOR A PERSISTENT E/NE WIND OFF LAKE SUPERIOR AND KEEP MUCH OF THE NORTHLAND UNDER THE INFLUENCE OF MOSTLY CLOUDY SKIES THROUGH THE WEEK. THE LACK OF SUN...COMBINED WITH A RELATIVELY COLD AIR MASS...850MB TEMPS -11 DEG C...WILL KEEP AFTERNOON HIGHS IN THE LOWER 30S AND OVERNIGHT LOWS IN THE TEENS. ROUGHLY 5-10 DEG BELOW AVERAGE. COULD SEE A FEW WEAK WAVES ROTATE WWD FROM THE UPPER TROUGH OVER ERN CANADA EARLY NEXT WEEK...BUT ONLY A SLIGHT CHANCE OF LIGHT SNOW IS POSSIBLE FROM THESE...WITH LITTLE TO NO SNOW ACCUMULATING. AVIATION.../18Z TAF ISSUANCE/ VFR CONDITIONS TODAY WITH A CHANCE OF A LOW/MID LEVEL STRATO-CU SCT DECK FORMING AFTER 21Z. FAIRLY DRY AIR IN PLACE UNDER HIGH PRESSURE SO...ANY CLOUDS THAT DO TRY TO FORM TODAY WILL NOT BECOME THICK ENOUGH FOR BKN CIGS TO FORM. WINDS WILL REMAIN LIGHT AND FROM THE NORTH. AS HIGH PRESSURE SETTLES IN TONIGHT AND WINDS BECOME CALM...THE POTENTIAL FOR FOG RETURNS. HAVE INCREASED AMT AND DURATION OF FOG WITH LOW-END IFR OR LIFR VSBYS POSSIBLE. && .POINT TEMPS/POPS... DLH -1 30 12 32 / 0 0 10 10 INL -7 29 9 31 / 0 0 10 10 BRD -3 31 12 33 / 0 0 0 10 HYR -5 34 8 34 / 0 0 0 10 ASX 2 32 11 32 / 0 0 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...DAP AVIATION...DAP
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1226 AM CDT WED MAR 20 2013 .UPDATE... ISSUED AT 1226 AM CDT WED MAR 20 2013 FCST TEMPS WERE RUNNING A LITTLE TOO COOL AGAINST THE OBSERVED TEMP CURVES. SO CURRENT OBS WERE MERGED WITH GFS LAMP TEMPS TO GET THE FCST BACK ON TRACK THE NEXT 3-6 HRS. SATL SHOWS THE BATCH OF MID-LEVEL CIGS WILL BE OUT OF THE FCST AREA BY 07Z. THEN JUST SCT MID CLOUDS. FCST HAS THIS GENERAL TREND SO NO CHANGES NEEDED. && .SHORT TERM...(TONIGHT THROUGH WEDNESDAY) ISSUED AT 357 PM CDT TUE MAR 19 2013 MORNING UPPER AIR ANALYSIS INDICATES LONGWAVE TROUGHING OVER THE EASTERN-HALF OF THE CONUS WITH RIDGING OVER THE WEST. NORTHWESTERLY MID AND UPPER LEVEL FLOW PERSISTS OVER THE CENTRAL PLAINS AS A RESULT. TROPOSPHERIC FLOW OVER OUR AREA MAXES OUT AT AROUND 120KTS PER 12Z SOUNDING DATA FROM KOAX AND KLBF. WATER VAPOR IMAGERY ALSO INDICATES A SUBTLE MID LEVEL PERTURBATION OVER EASTERN MONTANA...MOVING TO THE SOUTHEAST. AT THE SURFACE A TROUGH IS NOTED EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA AND KANSAS...WITH A COLD FRONT ALSO NOTED OVER THE DAKOTAS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTHWEST AS A RESULT. PROXIMITY SOUNDINGS FROM ACROSS CWA...PER RAP ANALYSIS AND LAPS DATA...SUGGEST VERY STEEP LOW TO MID LEVEL LAPSE RATES ARE IN PLACE...WITH NEARLY DRY ADIABATIC LAPSE RATES NOTED FROM THE SURFACE TO BETWEEN 750MB AND 700MB ACROSS MUCH OF OUR AREA. AS A RESULT...MODEST SBCAPE VALUES ON THE ORDER OF 100-200J/KG ARE IN PLACE ACROSS MUCH OF THE CWA. AN EXPANDING CU FIELD AS BEEN NOTED ON SATELLITE IMAGERY ACROSS MUCH OF NEBRASKA AS A RESULT...WITH KUEX AND KLNX SUGGESTING ELEVATED PRECIPITATION HAS RESULTED. SOME OF THIS PRECIPITATION IS MAKING IT TO THE SURFACE IN THE FORM OF RAIN AND GRAUPEL...BOTH OF WHICH WAS OBSERVED AT THE OFFICE BETWEEN 19Z AND 20Z. IN ADDITION...A COUPLE OF CG STRIKES HAVE BEEN DETECTED FROM HALL COUNTY INTO BUFFALO COUNTY WITH SOME OF THE MORE INTENSE CELLS. WITH ANY OMEGA STILL REMAINING WELL NORTHWEST OF OUR AREA OVER THE NORTHERN HIGH PLAINS...IN THE VICINITY OF THE AFOREMENTIONED MID LEVEL PERTURBATION...IT APPEARS THE CURRENT ACTIVITY IS BEING PROMOTED BY DIABATIC HEATING ALONE. SO...THIS ACTIVITY SHOULD CONTINUE THROUGH 22Z OR 23Z BEFORE THE LOSS OF DIABATIC HEATING IS REALIZED LATER THIS EVENING. WENT AHEAD WITH ISOLATED RAIN AND SNOW SHOWERS...ALONG WITH OCCASIONAL LIGHTNING...IN THE FORECAST THROUGH 00Z. THE SAME PROXIMITY SOUNDINGS FROM ACROSS THE CWA ALSO INDICATE VERY DRY LOWER TROPOSPHERIC AIR IN PLACE ACROSS THE AREA...THUS RESULTING IN DEEP INVERTED-V SOUNDINGS ACROSS THE ENTIRE CWA. GIVEN THE ABUNDANT VIRGA NOTED HERE AT THE OFFICE...ALONG WITH THE UPDRAFT STRENGTH NOTED FROM KUEX THROUGH THE PAST HOUR...FELT IT PRUDENT TO INTRODUCE BRIEF WIND GUSTS TO AROUND 50 MPH IN THE HWO THROUGH THIS EVENING. THE MID LEVEL PERTURBATION...CURRENTLY OVER THE NORTHERN HIGH PLAINS...IS EXPECTED TO SWEEP OVER OUR AREA TONIGHT. ANY OMEGA IN ASSOCIATION WITH THIS FEATURE IS EXPECTED TO REMAIN WEAK AND WITH NO OTHER SIGNIFICANT SOURCE OF LIFT DURING THE SHORT TERM FORECAST PERIOD...DRY CONDITIONS ARE FORECAST TONIGHT INTO TOMORROW. THE PASSAGE OF THE MID LEVEL PERTURBATION WILL ALSO HELP PUSH THE LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER THE DAKOTAS...ACROSS OUR AREA TONIGHT. THIS WILL IN TURN ALLOW A COOLER AIRMASS INTO OUR REGION THUS RESULTING IN SOMEWHAT COOLER WEDNESDAY MORNING LOWS WHEN COMPARED TO TUESDAY MORNING. OVERNIGHT LOWS IN THE TEENS AND 20S ARE CURRENTLY FORECAST FOR TONIGHT AS A RESULT. THE SURFACE RIDGE IS THEN EXPECTED TO PUSH OFF TO OUR EAST DURING THE DAY WEDNESDAY...WITH LOW LEVEL RETURN FLOW AND RESULTANT WARM AIR ADVECTION ALLOWING WEDNESDAY AFTERNOON HIGHS TO CLIMB INTO THE 40S AND LOWER 50S FOR MOST LOCATIONS ACROSS THE AREA. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 357 PM CDT TUE MAR 19 2013 WEDNESDAY NIGHT THROUGH TUESDAY. PRIMARY FORECAST CONCERN REVOLVES AROUND A MESSY PATTERN WITH MULTIPLE PRECIPITATION CHANCES DURING THE LATE WORK WEEK/WEEKEND TIME FRAME. STILL EXPECTING THE START OF THE LONG TERM PERIOD TO BE DRY...WITH MODELS IN GOOD AGREEMENT SHOWING NORTHWESTERLY FLOW SET UP IN THE UPPER LEVELS ACROSS THE REGION WEDNESDAY EVENING INTO THE OVERNIGHT HOURS...WITH AN ELONGATED LOW PRESSURE SYSTEM SPREAD FROM THE NORTHEASTERN CONUS THROUGH THE GREAT LAKES...AND SHORTWAVE RIDGING OVER THE ROCKIES AHEAD OF ANOTHER TROUGH ALONG THE WEST COAST. AT THE SURFACE...THE CWA SITS BETWEEN A RIDGE OF HIGH PRESSURE ALONG/JUST EAST OF THE MISSOURI RIVER...AND LOW PRESSURE EXTENDING FROM THE NORTHERN ROCKIES DOWN INTO SERN COLORADO...BRINGING SOUTHEASTERLY WINDS TO THE AREA. AS WE GET INTO EARLY THURSDAY MORNING...STILL SEEING THE MAIN MID/UPPER LEVEL TROUGH/LOW PRESSURE SYSTEM IN PLACE TO THE WEST...WITH THE FIRST OF A COUPLE OF DISTURBANCES EJECTED OUT AHEAD OF IT BEGINNING TO AFFECT THE REGION. MAIN CHANGE WITH THE MODELS HAS BEEN WITH MORE AGREEMENT BACKING OFF THE COVERAGE OF PRECIPITATION ACROSS THE CWA...THERE IS PLENTY OF DRIER AIR TO OVERCOME...AND BETTER CHANCES LOOK TO BE ACROSS EASTERN PORTIONS OF THE CWA DURING THE DAY ON THURSDAY AS THE MID LEVEL TROUGH AXIS SWINGS THROUGH AND FRONTOGENETICAL LIFT INCREASES. REALLY TAPERED BACK POPS...ESP ACROSS THE WRN THIRD OF THE CWA...IT IS POSSIBLE AFTER 12Z THURSDAY SOME WESTERN LOCATIONS MAY NOT SEE MUCH OF ANYTHING. DIDNT WANT TO COMPLETELY PULL POPS YET...WANT TO SEE SOME CONSISTENCY WITH THIS TREND FIRST. DECIDED TO HOLD ON TO THE MIXED PRECIPITATION ACROSS THE SWRN CWA DURING THE EARLY/MID MORNING HOURS ON THURSDAY...BUT CONFIDENCE IS NOT HIGH IN IT OCCURRING. IF PRECIPITATION OCCURS AT ALL IN THAT PART OF THE CWA...CANT COMPLETELY RULE OUT A BRIEF PERIOD OF MORE OF A MIX...BUT NOT EXPECTING IT TO AMOUNT TO MUCH. BUMPED UP HIGH TEMPERATURES ON THURSDAY ONCE AGAIN WITH MODELS TRENDING TOWARD THE POTENTIAL FOR DRIER CONDITIONS DURING THE AFTERNOON HOURS...SWRN LOCATIONS COULD REACH INTO THE LOWER/MID 40S. THINK THE NORTHEAST HALF WILL STRUGGLE WITH PRECIP/MORE CLOUD COVER LINGERING LONGER INTO THE DAY. SHOULD SEE A LULL IN THE ACTIVITY LATER IN THE DAY THURSDAY AND INTO THURSDAY EVENING...BUT IT WILL BE A BRIEF BREAK WITH THE NEXT DISTURBANCE TAKING AIM ON THE REGION. MODELS SHOWING THE MAIN TROUGH OVER THE NORTHWESTERN CONUS/NRN ROCKIES TRYING TO EVOLVE INTO A CLOSED CIRCULATION AS ANOTHER 110+KT UPPER LEVEL JET STREAK DIGS INTO THE WEST COAST. ANOTHER SHORTWAVE DISTURBANCE EJECTED OUT FROM THIS SYSTEM LOOKS TO BRING ANOTHER CHANCE FOR PRECIPITATION TO THE CWA. THERE CONTINUE TO BE SOME SLIGHT DIFFERENCES...BUT MODELS HAVE TRENDED TOWARD MORE AGREEMENT SHOWING THE TIMING COMING DURING THURSDAY NIGHT INTO THE FIRST HALF OF THE DAY ON FRIDAY. THINKING THE PRIMARY PRECIPITATION TYPE FOR MOST WILL BE SNOW...BUT CANT RULE OUT MORE OF A RA/SN MIX...MAINLY ACROSS THE SOUTHERN CWA. LIKE THURSDAY...TRENDED BACK POPS ON FRIDAY...THE BETTER CHANCES COME DURING THE 00-12Z FRIDAY TIME FRAME...WITH VERY LITTLE IN THE WAY OF POPS DURING THE AFTERNOON HOURS. BECAUSE OF THIS...ALSO BUMPED UP HIGHS ON FRIDAY...WITH MID 30S IN THE NORTHEAST TO LOWER/MID 40S IN THE SOUTHWEST. FRIDAY AFTERNOON AND INTO THE OVERNIGHT HOURS WILL BRING ANOTHER LULL IN THE ACTIVITY...BEFORE FOCUS QUICKLY TURNS TO A STRONGER SYSTEM WHICH WILL BRING THE POTENTIAL FOR MORE WIDESPREAD ACCUMULATING SNOWFALL TO THE REGION. BY EARLY SATURDAY MORNING...MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT SHOWING THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE BORDER OF MONTANA/CANADA...WHILE A PIECE OF ENERGY SWINGING FURTHER SOUTH INTO THE ROCKIES DOES THE SAME...AND ITS THIS SOUTHERN ONE WHICH WILL AFFECT OUR CWA. LIFT WILL BEGIN TO INCREASE ACROSS THE CWA OUT AHEAD OF THIS SYSTEM LATE FRIDAY NIGHT...ALREADY BRINGING PRECIPITATION CHANCES TO MAINLY THE WESTERN HALF OF THE CWA. THROUGH THE DAYTIME HOURS ON SATURDAY THIS UPPER LEVEL LOW WILL CONTINUE TO PUSH EAST...BRINGING INCREASING PRECIPITATION CHANCES...AND BY 00Z LOOKS TO BE OVER CENTRAL/ERN PORTIONS OF COLORADO. THERE ARE SOME TIMING DIFFERENCES...THE ECMWF/GFS ARE IN PRETTY GOOD AGREEMENT...WITH THE GEM A TOUCH SLOWER. WHAT HAPPENS THEN THROUGH THE OVERNIGHT HOURS SATURDAY NIGHT AND THEN INTO SUNDAY IS GOING TO DEPEND ULTIMATELY ON THE PATH/TIMING OF THIS UPPER LEVEL LOW. THE TIMING/PATH DIFFERENCES BETWEEN THE MODELS CONTINUE...BUT THEY ALL BRING MORE WIDESPREAD SNOWFALL ACCUMULATION. THIS IS ESPECIALLY TRUE WITH THE GEM...WHICH IS THE SLOWEST AND MOST WOUND UP SYSTEM COMPARED TO THE ECMWF/GFS...BUT ITS PATH IS SOMEWHAT IN BETWEEN THE TWO...TAKING IT MORE THROUGH CENTRAL KS. THERE ARE PLENTY OF THINGS TO WORK OUT IN THE COMING DAYS...AND EXPECT MODEL CHANGES...BUT THOSE WITH WEEKEND PLANS NEED TO KEEP AN EYE ON THIS SYSTEM. AS FAR AS TEMPERATURES GO...EXPECTING HIGHS TO STRUGGLE TO GET OUT OF THE MID 30S BOTH SATURDAY AND SUNDAY. LOOKING AHEAD TO MONDAY AND TUESDAY...KEPT THE FORECAST DRY...BUT THE MESSY UPPER LEVEL PATTERN REMAINS. MODELS KEEP THE REGION UNDER THE INFLUENCE OF A BROAD TROUGH...WITH PIECES OF ENERGY/LOW PRESSURE SYSTEMS ROTATING AROUND EACH OTHER. IN THIS PATTERN...CERTAINLY WOULNDT BE SEEING MUCH/IF ANY WARM UP...WITH HIGHS REMAINING IN THE 30S /AVERAGE FOR THIS TIME OF YEAR IS THE LOWER 50S/...AND ITS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME OF THIS ENERGY COULD BRING ANOTHER CHANCE FOR PRECIPITATION...ESP TUESDAY. BUT AT THIS POINT...WITH THERE ALREADY ENOUGH UNCERTAINTY THROUGH THE WEEKEND...WASNT CONFIDENT ENOUGH TO GO WITH ANY POPS FOR DAY 7. && .AVIATION...(FOR THE 06Z TAF THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1226 AM CDT WED MAR 20 2013 REST OF TNGT: VFR. A BATCH OF MID-LEVEL CIGS HAS DROPPED S OF THE TERMINAL AND JUST A FEW-SCT 7-9K FT CLOUDS WILL DRIFT THRU. WINDS WILL REMAIN NNE BELOW 10 KTS AND GRADUALLY DIMINISHING. AFTER 10Z WINDS WILL BECOME LGT AND VARIABLE AS HIGH PRES SLIDES THRU. WED: VFR WITH JUST A COUPLE SKIFFS OF 25K FT CIRRUS. LGT AND VARIABLE WINDS ORGANIZE FROM THE NW BELOW 10 KTS BEFORE DIMINISHING AGAIN 21Z-03Z. WED EVE: VFR MID-LEVEL CIGS INVADE WITH WINDS DEVELOPING FROM THE ESE AT 10-15 KTS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...BRYANT LONG TERM...ADO AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
755 PM EDT THU MAR 21 2013 .SYNOPSIS... COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP OVER THE DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE CAROLINAS AND MID ATLANTIC ON SUNDAY. && .NEAR TERM /THROUGH FRIDAY NIGHT/... AS OF 300 PM THURSDAY... THROUGH TONIGHT: SURFACE INSOLATION AND ANOMALOUSLY COLD TEMPS ALOFT (H85 TEMP OF -10C) DUE TO STRONG COLD ADVECTION EARLIER THIS MORNING HAS RESULTED IN VERY STEEP LOW-LEVEL LAPSE RATES AND MARGINAL DIURNAL DESTABILIZATION THIS AFTERNOON...WITH PERHAPS 50-100 J/KG OF SHALLOW MLCAPE (EQ LEVEL 7-10 KFT) AS OF 18Z. A POTENT SHORTWAVE (PER WV IMAGERY AND THE LATEST RAP DATA) WAS CENTERED OVER WV/VA AT 18Z...ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC GYRE CENTERED OVER NEW ENGLAND. DPVA ASSOCIATED WITH THIS FEATURE WILL BEGIN TO WANE OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN OVER THE NEXT SEVERAL HOURS AS THE SHORTWAVE PROGRESSES EAST TO THE DELMARVA. AS A RESULT...ISOLD SNOW SHOWERS ASSOC/W DPVA IN THE PRESENCE OF MARGINAL INSTABILITY (EXTENDING INTO THE ICE NUCLEATION ZONE) WILL GRADUALLY WANE AND END OVER THE NEXT FEW HOURS...BETWEEN 18-20Z. NW WINDS WILL INCREASE TO 10-15 MPH SUSTAINED WITH GUSTS UP TO 25 MPH DURING THE 19-22Z TIME-FRAME AS PRESSURE RISES ENSUE IN THE WAKE OF THE SHORTWAVE. WINDS WILL GRADUALLY DIMINISH THIS EVENING INTO TONIGHT AS THE NOCTURNAL INVERSION DEVELOPS AND THE MSLP GRADIENT WEAKENS FROM W-E. GIVEN CLEAR SKIES AND AN ANOMALOUSLY COLD/DRY AIRMASS IN PLACE...EXPECT LOWS WELL BELOW NORMAL...PERHAPS NEAR RECORD COLD FOR MARCH 22. EXACTLY HOW MUCH TEMPS FALL WILL DEPEND PRIMARILY ON WHEN WINDS DIMINISH...WHICH SHOULD OCCUR EARLIER IN THE WESTERN PIEDMONT AND LATEST IN THE COASTAL PLAIN. WILL INDICATE LOWS RANGING FROM THE LOWER TO MID 20S...COLDEST IN RURAL AND LOW-LYING AREAS...ESP IN THE WESTERN PIEDMONT. FRIDAY AND FRIDAY NIGHT: HEIGHTS WILL RISE DURING THE DAY FRIDAY AND FLOW ALOFT WILL BECOME INCREASINGLY UNIDIRECTIONAL AS THE ANOMALOUSLY COLD CYCLONIC GYRE CENTERED OVER NEW ENGLAND SHIFTS TOWARD THE CANADIAN MARITIMES. EXPECT SUNNY SKIES AND WARMER TEMPS THAN TODAY IN ASSOC/W LOW-LEVEL WARM ADVECTION FROM THE WEST/WSW THROUGHOUT THE DAY. WILL INDICATE HIGHS IN THE LOWER/MID 50S...SIMILAR TO MOS GUIDANCE...THOUGH IT IS POSSIBLE THAT A FEW LOCATIONS COULD REACH THE UPPER 50S GIVEN FULL SUN. EXPECT INCREASING MID/UPPER LEVEL CLOUD COVER FRIDAY NIGHT AS MOISTURE ADVECTS DOWNSTREAM OF PRECIPITATION EXPECTED TO DEVELOP IN VICINITY OF A STRENGTHENING FRONTAL ZONE ALONG THE GULF COAST...IN ADVANCE OF AN UPPER LEVEL TROUGH DIGGING SOUTHEAST INTO THE ROCKIES. THE BEST LOW-LEVEL MOISTURE RETURN AND WARM ADVECTION IS EXPECTED TO REMAIN WEST AND SOUTHWEST OF CENTRAL NC...THOUGH IT IS POSSIBLE THAT MID-LEVEL FRONTOGENESIS MAY ALSO CONTRIBUTE TO ASCENT OVER WESTERN PORTIONS OF THE STATE. GIVEN THE DRY ANTECEDENT AIRMASS IN PLACE... AT THIS TIME PREFER TO KEEP THE FORECAST DRY THROUGH FRIDAY NIGHT. GIVEN INCREASING MID/UPPER LEVEL CLOUD COVER FROM SW-NE...EXPECT LOWS WARMER THAN TONIGHT...RANGING FROM 30-37F...COOLEST IN RURAL AND LOW-LYING AREAS EAST AND NE OF THE TRIANGLE. -VINCENT && .SHORT TERM /SATURDAY THROUGH SUNDAY/... AS OF 1230 PM THURSDAY... A COLD RAIN EXPECTED LATE SATURDAY THROUGH SUNDAY... STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE STRONGLY NEGATIVE PHASE OF BOTH THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC OSCILLATION (NAO) ARE FORECAST TO CONTINUE THROUGH EARLY NEXT WEEK...KEEPING TEMPERATURES MUCH BELOW NORMAL (LIKELY 15-20 DEGREES) THROUGH SUNDAY. SEVERAL MID/UPPER DISTURBANCES WILL MOVE EAST OUT OF THE ROCKIES IN SUPPRESSED FASHION ACROSS THE DEEP SOUTH...WITH THE POLAR FRONT POSITIONED WELL SOUTH (ALONG THE GULF OF MEXICO). THE MOST SUBSTANTIAL SHORTWAVE IS FORECAST TO EMERGE ACROSS THE SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY EAST ACROSS THE TENNESSEE VALLEY AND CENTRAL APPALACHIANS LATE IN THE WEEKEND INTO EARLY MONDAY. THIS SHOULD LEAD TO A "MILLER-B" SURFACE LOW PRESSURE EVOLUTION AND HYBRID COLD AIR DAMMING EVENT SUNDAY INTO EARLY MONDAY. AHEAD OF THIS WAVE...STRENGTHENING SSW FLOW AND WARM ADVECTION BETWEEN H925 AND H7 SHOULD SPREAD SOME LIGHT PRECIP ACROSS THE SOUTHEAST UNITED STATES AS EARLY AS SATURDAY AS THE 850MB FRONT LIFTS NORTH ACROSS AL/GA/SC. HOWEVER... MODELS CONTINUE TO DISAGREE ON THE NORTHWARD EXTENT OF MEASURABLE PRECIPITATION. THE LATEST NAM AND GFS RUNS CONTINUE TO BRING SOME LIGHT MEASURABLE RAIN INTO OUR WESTERN AND SOUTHERN COUNTIES LATE FRIDAY NIGHT AND EARLY SATURDAY. THIS WOULD BE ASSOCIATED WITH A LEAD DISTURBANCE AND PARTIAL THICKNESSES BECOME WARM ENOUGH FOR ALL RAIN. THE EC HAS NOT BEEN AS AGGRESSIVE WITH THE LIGHT MEASURABLE RAIN WITH THE LEAD WAVE THIS FAR NORTHEAST...BUT GIVEN THAT THE NAM AND GFS HAVE HAD 4 CONSECUTIVE RUNS WITH THE SAME FORECAST OF LIGHT QPF...WE WILL KEEP LOW END CHANCES FOR THE SOUTHERN ZONES (ALBEMARLE TO FAYETTEVILLE) LATE FRIDAY NIGHT INTO MID-DAY SATURDAY. OTHERWISE...GIVEN THE EXTENT OF THE DRYNESS THE ANTECEDENT AIR MASS IS EXPECTED TO BE... PREFER TO STICK WITH THE DRY EC OVER THE NORTHERN COUNTIES THROUGH SATURDAY. HIGHS SATURDAY SHOULD BE FAIRLY UNIFORM ACROSS THE REGION...WITH THE POSSIBLE LIGHT RAIN EARLY IN THE SOUTH...HIGHS SHOULD BE ONLY IN THE 50-55 RANGE MOST AREAS. IF SOME LIGHT RAIN IS MEASURED...TEMPS SHOULD BE EVEN COOLER. FOR SATURDAY NIGHT AND SUNDAY...EXPECT RAIN TO OVERSPREAD/DEVELOP NORTHWARD ACROSS OUR REGION WITH THE APPROACH OF THE STRONG MID/UPPER LEVEL WAVE FROM THE WEST. THE GFS AND NAM CONTINUE TO DRIVE A STRENGTHENING SURFACE WAVE NE THROUGH THE TENNESSEE VALLEY INTO THE LOWER OHIO VALLEY SAT NIGHT AND SUNDAY...WITH SECONDARY BECOMING PRIMARY LOW PRESSURE DEVELOPMENT OFF THE SC COAST SUNDAY. WITH THE LATTER EXPECTED TO TRACK ALONG THE COAST OF NC LATE SUNDAY INTO SUNDAY NIGHT...HYBRID CAD WILL BECOME ENTRENCHED OVER CENTRAL NC THROUGHOUT THE EVENT. SENSIBLE WEATHER WILL INCLUDE...RAIN DEVELOPING SATURDAY NIGHT WITH LOWS OF 35-40. RAIN TAPERING TO AREAS OF DRIZZLE LATE SUNDAY. COLD WITH HIGHS IN THE 40S EXCEPT UPPER 30S NW. QPF ON THE ORDER OF 0.50 TO 0.75 EXPECTED (MAINLY BETWEEN 06Z AND 15Z SUNDAY...TAPERING TO LIGHT 0.10 AMOUNTS SUNDAY AFTERNOON). STORM TOTALS SHOULD REMAIN BELOW 1 INCH. STRONG CAA WILL FOLLOW THE STORM INTO NC FROM THE NW BEGINNING LATE SUNDAY NIGHT. LOWS 35-40 (CLEARING LATE SUNDAY NIGHT). && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 1230 PM THURSDAY... STRONG CAA ON MONDAY IN THE REAR OF THE DEPARTING STORM MOVING OUT INTO THE ATLANTIC WILL KEEP HIGHS ONLY IN THE 40S TO LOWER 50S (15-20 DEGREES BELOW NORMAL). NW WINDS 15-20 MPH WILL GUST TO 30 MPH. SOME VERY LIGHT SNOW SHOWERS MAY OCCUR ESPECIALLY IN AREAS N-E OF RALEIGH (NORTHERN COASTAL PLAIN)... BUT NOTHING SIGNIFICANT EXPECTED. OTHERWISE... PARTLY SUNNY AND WINDY. CLEAR AND COLD MONDAY NIGHT SHOULD YIELD LOWS IN THE UPPER 20S AND LOWER 30S (10-15 DEGREES BELOW NORMAL). TUESDAY THROUGH THURSDAY... A MOSTLY DRY AND CHILLY PATTERN SHOULD CONTINUE WITH THE DEEP TROUGH EXPECTED TO RELAX A BIT MID-LATE WEEK. HOWEVER...A STRONG SURFACE HIGH SHOULD EXTEND FROM THE NORTHERN PLAINS DEEP INTO THE GULF COAST STATES ENSURING CAA WILL BE DELIVERED DEEP INTO THE SE STATES THROUGH THE PERIOD. MOSTLY CLEAR/MOSTLY SUNNY SKIES EXPECTED MONDAY NIGHT THROUGH THURSDAY. LOWS GENERALLY AT OR SLIGHTLY BELOW 32. HIGHS 50-55. THESE READINGS WILL REMAIN AROUND 15 DEGREES BELOW NORMAL. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 755 PM THURSDAY... 24 HOUR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. EXPECT CLEAR SKIES OVERNIGHT WITH WINDS 5-10 KNOTS OUT OF THE NORTHWEST. ANY REMAINING GUSTS FROM THIS AFTERNOON WILL BE SUBSIDING OVER THE NEXT HOUR OR TWO. FOR FRIDAY...WINDS WILL PICK UP TO NEAR 10 KNOTS SUSTAINED WITH LIGHT GUSTING. WINDS WILL SHIFT BY LATE MORNING OR EARLY AFTERNOON TO MORE OF A WESTERLY OR WEST SOUTHWESTERLY DIRECTION. SOME HIGH CLOUDS AT 15-20 KFT WILL OVERSPREAD THE AREA BY THE END OF THE TAF PERIOD. LONG TERM: VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH FRIDAY EVENING WITH A CHANCE FOR MVFR CEILINGS EARLY SATURDAY MORNING. ADVERSE CONDITIONS ARE EXPECTED LATE SATURDAY THROUGH SUNDAY IN ASSOCIATION WITH A LOW PRESSURE SYSTEM. SUB-VFR CONDITIONS SHOULD LINGER THROUGH MONDAY BEFORE RETURNING TO VFR LATE MONDAY OR TUESDAY. && .FIRE WEATHER... THE SPECIAL WEATHER STATEMENT FOR INCREASED FIRE DANGER WILL BE ALLOWED TO REMAIN IN EFFECT THROUGH 00Z THIS EVENING IN ASSOC/W RH VALUES AT OR BELOW 25% AND NW WINDS SUSTAINED AT 10-15 MPH WITH GUSTS UP TO 25 MPH DURING THE MID/LATE AFTERNOON HOURS. -VINCENT && .RECORD LOWS... MARCH 22: RDU: 22F IN 1986 GSO: 22F IN 1986 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...ELLIS FIRE WEATHER...VINCENT
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
259 PM EDT WED MAR 20 2013 .SYNOPSIS... A WEAK FRONT WILL MOVE THROUGH EASTERN NORTH CAROLINA TONIGHT. HIGH PRESSURE WILL BUILD IN THURSDAY NIGHT. A SERIES OF WEAK LOW PRESSURES WILL MOVE THROUGH THE AREA THROUGH THE WEEKEND. A STRONG SYSTEM WILL MOVE INTO LATE SUNDAY. HIGH PRESSURE WILL BILD IN MONDAY NIGHT AND REMAIN THROUGH MIDWEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 245 PM WED...UPPER TROUGH OVER THE PLAINS STATES WILL DEEPEN AND STRONG SHORT WAVE WILL BRING THE BASE OF THE TROUGH THROUGH NORTH CAROLINA TONIGHT. MODELS IN GOOD AGREEMENT ON TIMING OF THE FRONT THROUGH THE AREA...ALTHOUGH RUC IS A LITTLE SLOWER. ALSO SOME DIFFERENCES IN PTYPE...ECMWF PTYPE FIELD IS CALLING IT FROZEN. HOWEVER FORECAST SOUNDINGS ALL HAVE ABOVE FREEZING NEAR THE SURFACE...AND HAVE GONE WITH TEMPERATURES IN THE MID TO UPPER 30S ACROSS THE AREA TONIGHT. PWS A LESS THAN HALF AN INCH AND SOUNDINGS DONT COMPLETELY SATURATE. SO WILL KEEP ONLY A SLIGHT CHANCE OF LIQUID SHOWERS TONIGHT WITH LITTLE TO NO QPF. && .SHORT TERM /THURSDAY/... AS OF 250 PM WED...SHOWERS WILL MOVE OUT DURING THE MORNING HOURS AS UPPER LEVEL ENERGY SWINGS THROUGH. 8H TEMPERATURES QUITE COOL FOR THIS TIME OF YEAR...AND WITH ANOTHER PIECE OF ENERGY SWINGING OVER THE AREA KEEPING THINGS MIXED UP...TEMPERATURES WILL HAVE A HARD TIME CLIMBING OUT OF THE MIDDLE 40S DURING THE DAY. LOW PRESSURE WILL DEEPEN AS IT MOVES OFF THE COAST WITH BREEZES REACHING 15 TO 20 MPH. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... AS OF 240 PM WEDNESDAY...COLD CANADIAN HIGH PRESSURE WILL BUILD OVER THE AREA WITH BELOW FREEZING TEMPS OVER MUCH OF THE AREA LATE THU NIGHT INTO EARLY FRI MORN AS WINDS DECOUPLE ESPECIALLY AWAY FROM THE COAST. THERE IS EVEN THE POSSIBILITY THAT WINDS WILL BECOME LIGHT ALONG THE OBX WITH A FROST OR FREEZING TEMPERATURES. SINCE THE SPRING GROWING SEASON HAS ALREADY BEGUN FOR THE OBX...AND BEGAN TODAY FOR CARTERET AND ONSLOW COUNTIES HAVE ISSUED A FREEZE WATCH FOR LATE THU NIGHT INTO EARLY FRI MORN FOR THESE AREAS. UPPER ENERGY WILL MOVE INTO THE FOUR CORNERS REGION WITH DEVELOPMENT OF A SURFACE LOW LATE FRIDAY. LOW PRESSURE WILL DEEPEN AS IT MOVES EAST INTO THE MID MISSISSIPPI VALLEY BY EARLY SUNDAY. ANOTHER SURFACE LOW WILL DEVELOP OVER THE NORTH CENTRAL GULF OF MEXICO. THIS LOW WILL MOVE UP THE CAROLINA COAST DEEPENING AS IT MOVES AWAY FROM THE REGION LATE MONDAY. ECMWF NOT AS STRONG WITH THE DEEPENING AS THE GFS. WILL CONT WITH LOW POPS FOR THE SOUTHERN COUNTIES FRIDAY NIGHT/SATURDAY AHEAD OF AN UPR LVL IMPL THEN HIGH CHANCE POPS FOR SUNDAY AND SUNDAY NIGHT AS THE LOW MOVES UP THE COAST WITH GOOD LOW LEVEL MOISTURE ADVECTION SPLY ON SUNDAY. MODELS CONT TO SHOW SOME INSTABILITY NEAR THE COAST ON SUNDAY SO WILL KEEP A SLIGHT CHANCE OF TSTMS AS WELL. COOLER THAN NORMAL TEMPS EXPECTED IN THE LONG TERM WITH LOWER 500 MB HEIGHTS CONTINUING. COLDEST TEMPS EXPECTED ON THU NIGHT FRI MORN FROM THE MID 20S WELL INLAND TO THE LOWER AND MID 30S OBX. FOR THE REMNDR OF THE LONG TERM PERIOD HIGHS WILL BE IN THE 50S AND LOWS FROM THE MID 30S INLAND TO THE LWR 40S ON THE COAST. && .AVIATION /18Z WEDNESDAY NIGHT THROUGH SUNDAY/... SHORT TERM /THROUGH THURSDAY AFTERNOON/... AS OF 125 PM WED...VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. SOME MID/HIGH CLOUDS ARE STREAMING INTO EASTERN NC FROM THE SOUTHWEST AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM PROGGED TO MOVE WELL OFFSHORE. ANTICIPATE CLOUD COVER TO CONTINUE THROUGH MUCH OF THIS AFTERNOON/EVENING. BRIEF CLEARING IS ANTICIPATED AS THE SYSTEM MOVES FURTHER OUT TO SEA. HOWEVER..SOME MID LEVEL CLOUDS ASSOCIATED WITH AN UPPER LEVEL TROUGH WILL PIVOT ACROSS THE AREA TOMORROW EARLY MORNING. PRECIPITATION WITH THIS SYSTEM SEEMS MINIMAL AT THIS TIME. WINDS WILL BE VARIABLE THROUGH THE OVERNIGHT. HOWEVER...AS THE UPPER LEVEL TROUGH MIGRATES OVERHEAD AND THE STRONG LOW PRESSURE SYSTEM CONTINUES TO MOVE OUT TO SEA...GUSTY NW WINDS WILL DEVELOP. LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 240 PM WEDNESDAY...SHOULD SEE GENERALLY VFR CONDITIONS THURSDAY AND FRIDAY AS COOL CANADIAN HIGH PRESSURE DOMINATES. MOISTURE RETURNS DURING THE WEEKEND AS LOW PRESSURE MOVES UP THE NC COAST. EXPECT SUB VFR CONDS IN SHOWERS...ESPECIALLY ON SUNDAY. && .MARINE... SHORT TERM /THROUGH THURSDAY/... AS OF 255 PM WED...NORTHEAST WIND OVER THE WATESR THIS AFTERNOON RUNNING 10 TO 15 KNOTS WITH SEAS 2 TO 3 FEET. AN UPPER LEVEL TROUGH WILL MOVE THROUGH THE AREA TONIGHT...PUSHING A COLD FRONT THROUGH THE WATERS AROUND SUNRISE. WINDS AHEAD OF THE FRONT WILL TURN FROM NORTHEAST TO SOUTHEAST AND THEN SOUTHWEST...THEN BECOME NORTHWEST AGAIN BEHIND THE FRONT. AS LOW PRESSURE MOVES OFF SHORE IT WILL START TO DEEPEN...TIGHTENING GRADIENT OVER THE NC COASTAL WATESR DURING THE AFTERNOON. WIND AND SEAS WILL REACH SCA CRITERIA DURING THE LATE AFTERNOON HOURS. LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... AS OF 240 PM THURSDAY...NORTHWEST WINDS BEHIND SHORTWAVE SHOULD CONTINUE IN THE 20 TO 25 KNOT RANGE ACROSS THE NRN AND CNTRL COASTAL WATERS THROUGH ABOUT 06Z WITH SEAS BUILDING INTO THE 4-7 FT RANGE. SCA HAS BEEN ISSUED FOR THIS AREA. WEAK HIGH PRES WILL RESULT IN THE WINDS AT 15 KNOTS OR LESS AND SEAS AT 4 FEET OR LESS FRIDAY AND SATURDAY. LOW PRESSURE THEN MOVES UP THE COAST WITH E TO NE WINDS INCREASING SUNDAY THEN GUSTY WEST WINDS FOLLOW ON THE BACKSIDE OF THE LOW ON MONDAY. SEAS ARE EXPECTED TO BE IN THE 4-7 FOOT RANGE FOR SUNDAY AND MONDAY. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR NCZ095-098-103-104. MARINE...SMALL CRAFT ADVISORY FROM 1 PM THURSDAY TO 2 AM EDT FRIDAY FOR AMZ150-152-154. && $$ SYNOPSIS...CGG NEAR TERM...CGG SHORT TERM...CGG LONG TERM...JAC AVIATION...JAC/LEP MARINE...CGG/JAC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
846 PM CDT THU MAR 21 2013 .DISCUSSION...LATEST RADAR IMAGERY/SURFACE OBSERVATIONS CONTINUE TO SHOW AN AREA OF LIGHT SNOW IN THE WEST WITH LITTLE MOVEMENT EASTBOUND. THE RAP MAINTAINS A VERY SLOW PROGRESSION EAST THROUGH FRIDAY AFTERNOON. WATER VAPOR IMAGERY SHOWS AN UPPER LOW BEGINNING TO FORM OVER NORTH CENTRAL MONTANA WITH A SURFACE LOW BASICALLY UNDERNEATH THE UPPER LOW FORMATION. THE SURFACE/UPPER AIR LOW IS FORECAST TO MOVE TO NEAR BAKER MONTANA BY 12Z FRIDAY. HENCE...EXPECT A CONTINUATION OF A FAIRLY SHARP DELINEATION FROM SNOW TO NO SNOW. WILL AWAIT THE 00Z NAM...BUT TRENDS ARE FOR ANOTHER DELAY OF THE LIGHT SNOW SHIELD INTO CENTRAL NORTH DAKOTA...NOT UNTIL MID TO LATE MORNING FOR KBIS/KMOT. REST OF FORECAST REMAINS ON TRACK. && .AVIATION...LIGHT SNOW ACROSS THE WESTERN AERODROMES OF KISN/KDIK PER LATEST SURFACE OBSERVATIONS/RADAR IMAGERY WITH MVFR/IFR CIGS/VSBYS THROUGH FRIDAY MORNING. THE CENTRAL AERODROMES OF KMOT AND KBIS WILL REMAIN VFR UNTIL 09Z FRIDAY...WITH MVFR CIGS DEVELOPING THEREAFTER. LIGHT SNOW/IFR VSBYS WILL HOLD OFF UNTIL 13Z TO 16Z FOR KBIS NORTH TO KMOT. KJMS WILL REMAIN VFR THROUGH 15Z FRIDAY BEFORE EXPERIENCING MVFR CIGS. THE LIGHT SNOW IS NOT EXPECTED AT KJMS UNTIL 22Z FRIDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/AVIATION...KS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1151 PM EDT THU MAR 21 2013 .SYNOPSIS... AN UPPER LEVEL LOW OVER SOUTHEAST CANADA WILL REMAIN ANCHORED NORTH OF PENNSYLVANIA THROUGH THE REST OF THE WORKWEEK. GUSTY WEST TO NORTHWEST WINDS WILL CONTINUE TO FILTER COLD AIR INTO THE REGION. THIS WILL ALSO PRODUCE OCCASIONAL SNOW SHOWERS ACROSS THE WESTERN MOUNTAINS. A STORM SYSTEM MAY MOVE OUT OF THE MID- MISSISSIPPI VALLEY LATER THIS WEEKEND AND COULD BRING ANOTHER ROUND OF WINTRY PRECIPITATION TO THE REGION LATE SUNDAY NIGHT AND MONDAY. THERE IS NO WARM-UP IN SIGHT...AS THE MONTH OF MARCH IS LIKELY TO END ON A WINTRY NOTE. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... MINOR CHANGES MADE FOR THIS 0230Z UPDATE. UPR SHORTWAVE AND SFC TROUGH AXIS MOVING ACROSS WRN PA LATE THIS EVENING. MEAN 925-850 MB FLOW OF ABOUT 30 KTS /AND VEERING TO THE NW/ WILL DRIVE MULTIPLE BANDS OF SNOW SHOWERS AND SOME BRIEFLY HEAVY SQUALLS WELL INLAND ACROSS THE ALLEGHENY PLATEAU OVERNIGHT. THIS WILL BRING A LIGHT ACCUMULATION ACROSS MOST OF THE HIGHER TERRAIN OF WRN AND NRN PENN. WILL KEEP THE LAKE EFFECT SNOW ADVISORY GOING FOR WARREN COUNTY THROUGH 16Z FRIDAY WHERE ANOTHER 2 TO 3 INCHES IS LIKELY... BRINGING 36-HOUR SNOW TOTALS UP TO 4-7 INCHES ACROSS THE SNOWBELT OF NW WARREN COUNTY. SCATTERED SNOW SHOWERS JUST EAST OF THE ALLEGHENY FRONT WILL BRING A LIGHT COATING TO SOME LOCATIONS. CLEAR TO PARTLY CLOUDY SKIES WILL OCCUR EARLY TONIGHT ACROSS THE LOWER SUSQ VALLEY...FOLLOWED BY MOSTLY CLOUDY SKIES AFTER MIDNIGHT WITH FLURRIES AND PERHAPS A BRIEF SNOW SHOWERS. WITH NOTHING ANOTHER CHILLY...BELOW NORMAL NIGHT IS IN STORE FOR CENTRAL PENNSYLVANIA...WITH LOW TEMPERATURES RANGING FROM THE MID TEENS ACROSS THE NORTHERN WESTERN MOUNTAINS...TO THE LOWER 20S IN THE SOUTHEAST. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... LAKE EFFECT SNOW SHOWERS WILL PERSIST NEAR...AND IMMEDIATELY DOWNWIND FROM LAKE ERIE OVER WARREN COUNTY. EXPECT A TOTAL OF 4 TO 7 INCHES TO ACCUMULATE BY LATE FRIDAY MORNING IN THE ADVISORY AREA...WITH LESSER AMOUNTS TO THE SOUTH AND EAST. WEST CENTRAL AND NORTH CENTRAL MOUNTAIN AREAS WILL GENERALLY SEE A COATING TO 2 INCHES THROUGH FRIDAY MORNING. UPSLOPE SNOW SHOWERS WILL ALSO CONTINUE THROUGH FRIDAY MORNING WITH SNOW ACCUMULATIONS OF 1-2 INCHES POSSIBLE OVER THE LAUREL HIGHLANDS. SNOW SHOWERS WILL SLOWLY DECREASE LATE FRIDAY AS SFC HIGH PRESSURE APPROACHES FROM THE OHIO VALLEY. WHILE SCATTERED ACTIVITY IS STILL EXPECTED INTO FRIDAY NIGHT...BELIEVE THE SIGNIFICANT ACCUMS WILL BE OVER BY FRIDAY AFTERNOON. MAXES ON FRIDAY WILL CONTINUE TO BE WELL BELOW NORMAL...RANGING FROM THE UPPER 20S OVER THE NORTHERN TIER TO THE LOWER TO MIDDLE 40S ACROSS THE SOUTHEAST. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... A SHORT PERIOD OF RISING HEIGHTS WILL MOVE ACROSS PA OVER THE WEEKEND HELPING TO BRING SNOW SHOWER ACTIVITY TO AN END. THE SHORTWAVE RIDGE IS AHEAD OF EXPECTED SIGNIFICANT LONGWAVE TROF DEVELOPMENT FORECAST TO TAKE PLACE ACROSS THE PLAINS OVER THE WEEKEND AS ENERGY DIVES SOUTH FROM CANADA. THE LARGE-SCALE PATTERN DOES FAVOR DEVELOPMENT OF A SFC LOW OVER THE MID MS VALLEY AND A MILLER TYPE-B SCENARIO AFTER THAT AS THE UPPER TROUGH SWINGS TO THE EAST. BUT...THE DEVIL REMAINS IN THE DETAILS. SO...EYES ARE CENTERED ON PERHAPS ANOTHER LATE WINTER/EARLY SPRING STORM FOR PA FROM PERHAPS LATE SUNDAY INTO MONDAY NIGHT. MOST MDLS AND ENSEMBLE MEMBERS DO BRING SOME PRECIP INTO AT LEAST SRN HALF OF PA FROM THIS SYSTEM. HOWEVER...THE BIG TROUBLES REMAIN TIMING...NORTHWARD EXTENT OF PRECIP DUE TO TIMING OF LOW TRANSFER...AND OF COURSE TEMPS AND P-TYPES DURING THE PRECIP. IN OTHER WORDS...EVERYTHING IS STILL UNCERTAIN. DID HAVE ENOUGH CONFIDENCE TO MAKE POPS AROUND 50 PCT IN THE S FOR TWO PERIODS...BUT IT IS STILL A DAY 5-6 /POTENTIAL/ STORM. PLENTY OF TIME FOR THE PROGS TO WAGGLE ALL DIFFERENT DIRECTIONS FOR MANY DAYS. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... A COLD NORTHWEST FLOW WILL GATHER MOISTURE FROM THE GREAT LAKES AND DEPOSIT IT AS SNOW SHOWERS ACROSS THE ALLEGHENY MOUNTAINS TONIGHT AND FRIDAY. SOME OF THE HEAVIEST SNOW SHOWERS WITH IFR VSBYS WILL LIKELY OCCUR BTWN 04Z-08Z AT JST WITH PASSAGE OF A WEAK SFC TROUGH. LATEST RUC SHOWS A TONGUE OF HIGHER LOW LVL MOISTURE ALONG THIS BOUNDARY SAGGING SOUTH INTO THE LAUREL HIGHLANDS DURING THIS TIME PERIOD. DRYING...DOWNSLOPING FLOW SHOULD RESULT IN MUCH BETTER FLYING CONDS OVERNIGHT EAST OF THE MTNS. CAN/T RULE OUT BRIEF VSBY RESTRICTIONS OVERNIGHT AT AOO/UNV/IPT...WHILE CONDS AT MDT AND LNS APPEAR VERY LIKELY TO REMAIN VFR. EXPECT DIMINISHING -SHSN OVR THE W MTNS ON FRIDAY...AS INVERSION HEIGHTS LOWER WITH APPROACH OF SFC HIGH. STILL...OCNL MVFR CIGS/VSBYS REMAIN POSSIBLE AT BFD THRU FRI EVENING. AN INTENSE LOW PRES SYSTEM OVR THE CANADIAN MARITIMES WILL CONTINUE TO BUFFET THE AREA WITH A GUSTY WNW WINDS. ALTHOUGH THE GUSTS MAY DIMINISH A BIT OVERNIGHT...BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS ARND 25KTS DURING LATE FRI AM AND AFTERNOON. OUTLOOK... SAT...NO SIG WX EXPECTED. SUN...SNOW POSS LATE ACROSS THE SOUTH. MON...SNOW POSS...ESP SOUTH. TUE...SNOW POSS...ESP LAUREL HIGHLANDS. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT FRIDAY FOR PAZ004. && $$ SYNOPSIS...DANGELO/DEVOIR/COLBERT NEAR TERM...LAMBERT/COLBERT SHORT TERM...DEVOIR/LA CORTE/LAMBERT LONG TERM...DANGELO/CERU AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
821 PM CDT THU MAR 21 2013 .UPDATE... WEAK MOISTURE CONVERGENCE AND LIMITED INSTABILITY PREVENTED THUNDERSTORM DEVELOPMENT ALONG THE DRY LINE THIS AFTERNOON/EARLY THIS EVENING. NOW WITH THE LOSS OF SURFACE HEATING...STORM CHANCES ALONG THE DRY LINE HAVE DECREASED SIGNIFICANTLY. THERE IS STILL A CHANCE OF SOME ELEVATED SHOWERS AND THUNDERSTORMS ACROSS THE NORTHERN HALF OF NORTH TEXAS WITH THE BEST STORM CHANCES ACROSS THE NORTHEAST ZONES JUST NORTH OF A WARM FRONT. FURTHER SOUTH...SOME WARM AIR ADVECTION SHOWERS ARE POSSIBLE...ESPECIALLY TOWARD MORNING. FOR THIS UPDATE...WE WILL LOWER EVENING POPS IN ALL ZONES AND MAKE SOME MINOR WIND/CLOUD COVER AND HOURLY TEMP/DEW POINT ADJUSTMENTS. 79 && .AVIATION... CLOUD COVER HAS PREVENTED GOOD SURFACE HEATING EAST OF THE DRY LINE AND CHANCES OF CONVECTION THIS EVENING NEAR DFW AIRPORTS LOOK CLOSE TO ZERO. GOOD MOISTURE RETURN THOUGH...AND MVFR CONDITIONS ARE EXPECTED TO DEVELOP LATER THIS EVENING AS CIGS CONTINUE TO LOWER. WITH FROPA NEAR SUNRISE...MVFR CIGS WILL LIKELY LINGER MUCH OF THE DAY...WITH A LIFT TO VFR FRIDAY AFTERNOON AND THEN MORE MVFR AFTER MIDNIGHT. 84 && .PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/ BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5 PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000 J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS. EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON AHEAD OF THE FRONT. THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO WARM TEMPERATURES THAN THE ECMWF. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 57 64 47 68 42 / 20 20 20 50 10 WACO, TX 62 71 50 74 42 / 10 20 20 50 5 PARIS, TX 48 58 45 58 37 / 50 30 20 50 20 DENTON, TX 51 60 45 65 39 / 30 20 20 40 10 MCKINNEY, TX 54 60 45 62 40 / 40 20 20 50 10 DALLAS, TX 58 64 48 68 43 / 20 20 20 50 10 TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10 CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10 TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5 MINERAL WELLS, TX 50 63 46 74 39 / 20 10 20 30 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 84/79
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
629 PM CDT THU MAR 21 2013 .AVIATION... CLOUD COVER HAS PREVENTED GOOD SURFACE HEATING EAST OF THE DRY LINE AND CHANCES OF CONVECTION THIS EVENING NEAR DFW AIRPORTS LOOK CLOSE TO ZERO. GOOD MOISTURE RETURN THOUGH...AND MVFR CONDITIONS ARE EXPECTED TO DEVELOP LATER THIS EVENING AS CIGS CONTINUE TO LOWER. WITH FROPA NEAR SUNRISE...MVFR CIGS WILL LIKELY LINGER MUCH OF THE DAY...WITH A LIFT TO VFR FRIDAY AFTERNOON AND THEN MORE MVFR AFTER MIDNIGHT. 84 && .PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/ BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5 PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000 J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS. EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON AHEAD OF THE FRONT. THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO WARM TEMPERATURES THAN THE ECMWF. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 57 64 47 68 42 / 30 20 20 50 10 WACO, TX 62 71 50 74 42 / 10 20 20 50 5 PARIS, TX 48 58 45 58 37 / 60 30 20 50 20 DENTON, TX 51 60 45 65 39 / 40 20 20 40 10 MCKINNEY, TX 54 60 45 62 40 / 50 20 20 50 10 DALLAS, TX 58 64 48 68 43 / 30 20 20 50 10 TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10 CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10 TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5 MINERAL WELLS, TX 50 63 46 74 39 / 40 10 20 30 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
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...CORRECT TYPO IN THE AVIATION FORECAST DISCUSSION.

.SHORT TERM...TONIGHT AND THURSDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A BROAD AND ELONGATED UPPER LEVEL LOW PRESSURE SYSTEM SPINNING FROM THE CENTRAL GREAT LAKES TO NEW ENGLAND EARLY THIS AFTERNOON. CLOUDS HAVE BEEN SPREADING SOUTH ACROSS THE UPPER PENINSULA AND NORTHERN WISCONSIN SO FAR TODAY...AS A RESULT OF SHORTWAVE LOBES ROTATING AROUND THE PARENT VORTEX...AND ALSO STEEPENING LOW LEVEL LAPSE RATES. THESE CONDITIONS ALSO PROMOTE CONDITIONS FOR SIGNIFICANT LAKE EFFECT SNOWS...WHICH ARE OCCURRING WITHIN THE SNOW BELTS OF THE WESTERN UPPER PENINSULA. IN FACT...IRONWOOD HAS OSCILLATED BETWEEN 1/2SM AND 3/4SM FOR MUCH OF THE DAY. LAKE EFFECT POTENTIAL IS THE MAIN FORECAST CONCERN OVER THE NEXT 24 HOURS AS WIND TRAJECTORIES BECOME MORE FAVORABLE FOR N-C WISCONSIN. TONIGHT...SHORTWAVE TROUGH WILL DIVE SOUTH ACROSS CENTRAL AND SOUTHERN WISCONSIN THIS EVENING...ON THE WESTERN FLANK OF THE UPPER LOW. NOT SOLD THAT PRECIP WILL TURN OFF AT SUNSET...THOUGH DIURNAL INSTABILITY WILL BE LOST. WILL KEEP LIGHT SNOW SHOWERS AND FLURRIES GOING FOR A GOOD CHUNK OF THE EVENING. BEHIND THE SHORTWAVE...LOW LEVEL WINDS TURN TO THE NNW. WIND TRAJECTORIES LOOK REALLY GOOD FOR A SOLID LAKE EFFECT EVENT FOR N-C WISCONSIN. THERMAL PROFILES ARE ALSO IN THE OPTIMAL DENDRITIC GROWTH ZONE THROUGH THE NIGHT...AND THERE IS SUFFICIENT MOISTURE IN THE 850-700MB LAYER AS WELL. ON THE MINUS SIDE...SUBSIDENCE WILL BE INCREASING THROUGH THE NIGHT AND LAKE INDUCED CAPE WILL GRADUALLY DIMINISH. THE LOCAL LAKE EFFECT PARAMETER DOES SHOW A SLIGHT DIMINISHING TREND TONIGHT...BUT NOT THAT SIGNIFICANT. A LIMITING FACTOR MAY BE THE 15 KT BL WINDS...IN WHICH THE NORTHERN PART OF VILAS COUNTY GETS ADVISORY CRITERIA SNOW...AND THE SOUTHERN HALF DOES NOT. SO THINK WILL GO WITHOUT AN ADVISORY AND ISSUE AN SPS FOR THE COUNTY TONIGHT...AND WILL HIGHLIGHT THAT SEVERAL INCHES OF SNOW ARE POSSIBLE ACROSS THE NORTHERN PART OF THE COUNTY. PARTIAL CLEARING SHOULD OCCUR OUTSIDE THE LAKE EFFECT BELT DURING THE OVERNIGHT HOURS...BUT DO NOT THINK WILL SEE DECOUPLING. AS A RESULT...LOW TEMPS WILL BE COMPARABLE TO LAST NIGHTS LOWS. THURSDAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER N-C WISCONSIN THROUGH EARLY AFTERNOON...BUT SHOULD DIMINISH AS DRY AIR INVADES FROM THE NORTH. ELSEWHERE...AFTER A MOSTLY CLEAR TO PARTLY CLOUDY START TO THE DAY...CLOUDS SHOULD BE INCREASING BY LATE MORNING OR EARLY AFTERNOON AS WILL STILL HAVE PLENTY OF LOW LEVEL MOISTURE AND STEEP LOW LEVEL LAPSE RATES AROUND. INCREASED CLOUD COVER...BUT KEPT THE SNOW CHANCES CONFINED TO THE SNOW BELT. HIGHS SEVERAL DEGREES WARMER THAN TODAY WITH HIGHS MAINLY IN THE MID TO UPPER 20S. .LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...MAIN FCST CONCERN IS TEMPERATURES. A LARGE UPPER LEVEL LOW WILL RESIDE OVER EASTERN CANADA AND THE EASTERN GREAT LAKES REGION EARLY IN THE PERIOD...BUT WILL SHIFT EAST BY FRI/SAT...ALLOWING WEAK RIDGING TO DEVELOP OVER WI. A LARGE CANADIAN SFC HIGH WILL RIDGE INTO THE WESTERN GREAT LAKES DURING THIS PERIOD...BRINGING DRY...BUT CONTINUED COOL CONDITIONS. WITH LOW-LEVEL WINDS TURNING NNE-NE...CONSIDERED THE POSSIBILITY OF SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES IN EASTERN WI... BUT WINDS ARE VERY LIGHT ON FRIDAY NIGHT...AND MOISTURE AND INSTABILITY ARE NOT VERY FAVORABLE ON SATURDAY...SO KEPT A DRY FCST INTACT. THE UPPER PATTERN WILL TRANSITION BACK TO A BROAD UPPER TROF LATE IN THE WEEKEND...AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK. THE ONLY SIGNIFICANT STORM OF THE WEEK IS A LOW PRESSURE SYSTEM WHICH MOVES THROUGH THE SOUTHERN PLAINS ON SATURDAY...THEN LIFTS NE THROUGH THE TENNESSEE VALLEY AND INTO THE MID-ATLANTIC STATES BY MONDAY. THIS STORM SHOULD PASS FAR ENOUGH SOUTH AND EAST OF THE REGION TO PREVENT ANY SIGNIFICANT PCPN DEVELOPMENT OVER C/NE WI. HOWEVER...LOW-LEVEL CYCLONIC FLOW AND THE PRESENCE OF THE BROAD UPPER TROF COULD BRING SCT LIGHT SNOW SHOWERS OR FLURRIES AT TIMES. FOR NOW...WILL MAINLY BE CARRYING SLIGHT CHC POPS FROM THE LATE WEEKEND THROUGH MIDWEEK. H8 TEMPS WILL NOT VARY MUCH OVER THE PERIOD...WITH MOST OF THE MEDIUM RANGE MODELS FORECASTING -8 TO -12 C. THIS SHOULD CONTINUE THE TREND OF BELOW NORMAL TEMPERATURES FOR THE NEXT WEEK...WITH LOWS IN THE TEENS AND LOWER 20S...AND HIGHS IN THE 30S. && .AVIATION...BKN TO OVC MVFR DECK TO DEVELOP ACROSS MUCH OF CENTRAL AND NORTH-CENTRAL WISCONSIN EARLY THIS AFTERNOON. SKY CONDITIONS TO TURN BKN AND OVC OVER NE WISCONSIN AS WELL...BUT ONLY SLIGHTLY HIGHER THAN MVFR. BEST CHANCE OF SNOW SHOWERS TO OCCUR MID AFTERNOON TO EARLY THIS EVENING...AND SOME POTENTIAL THAT VSBYS COULD DROP TO IFR IN THE SNOW SHOWERS. NNW WINDS TO KEEP LAKE EFFECT SNOW SHOWERS WITHIN THE SNOW BELTS OF N-C WISCONSIN TONIGHT WHERE A FEW INCHES OF ACCUMULATION IS POSSIBLE. SKIES TO PARTIALLY CLEAR EVERYWHERE ELSE. CLOUDS WILL THEN REDEVELOP BY LATE TOMORROW MORNING ACROSS THE REGION. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
233 PM CDT WED MAR 20 2013 .SHORT TERM...TONIGHT AND THURSDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A BROAD AND ELONGATED UPPER LEVEL LOW PRESSURE SYSTEM SPINNING FROM THE CENTRAL GREAT LAKES TO NEW ENGLAND EARLY THIS AFTERNOON. CLOUDS HAVE BEEN SPREADING SOUTH ACROSS THE UPPER PENINSULA AND NORTHERN WISCONSIN SO FAR TODAY...AS A RESULT OF SHORTWAVE LOBES ROTATING AROUND THE PARENT VORTEX...AND ALSO STEEPENING LOW LEVEL LAPSE RATES. THESE CONDITIONS ALSO PROMOTE CONDITIONS FOR SIGNIFICANT LAKE EFFECT SNOWS...WHICH ARE OCCURRING WITHIN THE SNOW BELTS OF THE WESTERN UPPER PENINSULA. IN FACT...IRONWOOD HAS OSCILLATED BETWEEN 1/2SM AND 3/4SM FOR MUCH OF THE DAY. LAKE EFFECT POTENTIAL IS THE MAIN FORECAST CONCERN OVER THE NEXT 24 HOURS AS WIND TRAJECTORIES BECOME MORE FAVORABLE FOR N-C WISCONSIN. TONIGHT...SHORTWAVE TROUGH WILL DIVE SOUTH ACROSS CENTRAL AND SOUTHERN WISCONSIN THIS EVENING...ON THE WESTERN FLANK OF THE UPPER LOW. NOT SOLD THAT PRECIP WILL TURN OFF AT SUNSET...THOUGH DIURNAL INSTABILITY WILL BE LOST. WILL KEEP LIGHT SNOW SHOWERS AND FLURRIES GOING FOR A GOOD CHUNK OF THE EVENING. BEHIND THE SHORTWAVE...LOW LEVEL WINDS TURN TO THE NNW. WIND TRAJECTORIES LOOK REALLY GOOD FOR A SOLID LAKE EFFECT EVENT FOR N-C WISCONSIN. THERMAL PROFILES ARE ALSO IN THE OPTIMAL DENDRITIC GROWTH ZONE THROUGH THE NIGHT...AND THERE IS SUFFICIENT MOISTURE IN THE 850-700MB LAYER AS WELL. ON THE MINUS SIDE...SUBSIDENCE WILL BE INCREASING THROUGH THE NIGHT AND LAKE INDUCED CAPE WILL GRADUALLY DIMINISH. THE LOCAL LAKE EFFECT PARAMETER DOES SHOW A SLIGHT DIMINISHING TREND TONIGHT...BUT NOT THAT SIGNIFICANT. A LIMITING FACTOR MAY BE THE 15 KT BL WINDS...IN WHICH THE NORTHERN PART OF VILAS COUNTY GETS ADVISORY CRITERIA SNOW...AND THE SOUTHERN HALF DOES NOT. SO THINK WILL GO WITHOUT AN ADVISORY AND ISSUE AN SPS FOR THE COUNTY TONIGHT...AND WILL HIGHLIGHT THAT SEVERAL INCHES OF SNOW ARE POSSIBLE ACROSS THE NORTHERN PART OF THE COUNTY. PARTIAL CLEARING SHOULD OCCUR OUTSIDE THE LAKE EFFECT BELT DURING THE OVERNIGHT HOURS...BUT DO NOT THINK WILL SEE DECOUPLING. AS A RESULT...LOW TEMPS WILL BE COMPARABLE TO LAST NIGHTS LOWS. THURSDAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER N-C WISCONSIN THROUGH EARLY AFTERNOON...BUT SHOULD DIMINISH AS DRY AIR INVADES FROM THE NORTH. ELSEWHERE...AFTER A MOSTLY CLEAR TO PARTLY CLOUDY START TO THE DAY...CLOUDS SHOULD BE INCREASING BY LATE MORNING OR EARLY AFTERNOON AS WILL STILL HAVE PLENTY OF LOW LEVEL MOISTURE AND STEEP LOW LEVEL LAPSE RATES AROUND. INCREASED CLOUD COVER...BUT KEPT THE SNOW CHANCES CONFINED TO THE SNOW BELT. HIGHS SEVERAL DEGREES WARMER THAN TODAY WITH HIGHS MAINLY IN THE MID TO UPPER 20S. .LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...MAIN FCST CONCERN IS TEMPERATURES. A LARGE UPPER LEVEL LOW WILL RESIDE OVER EASTERN CANADA AND THE EASTERN GREAT LAKES REGION EARLY IN THE PERIOD...BUT WILL SHIFT EAST BY FRI/SAT...ALLOWING WEAK RIDGING TO DEVELOP OVER WI. A LARGE CANADIAN SFC HIGH WILL RIDGE INTO THE WESTERN GREAT LAKES DURING THIS PERIOD...BRINGING DRY...BUT CONTINUED COOL CONDITIONS. WITH LOW-LEVEL WINDS TURNING NNE-NE...CONSIDERED THE POSSIBILITY OF SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES IN EASTERN WI... BUT WINDS ARE VERY LIGHT ON FRIDAY NIGHT...AND MOISTURE AND INSTABILITY ARE NOT VERY FAVORABLE ON SATURDAY...SO KEPT A DRY FCST INTACT. THE UPPER PATTERN WILL TRANSITION BACK TO A BROAD UPPER TROF LATE IN THE WEEKEND...AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK. THE ONLY SIGNIFICANT STORM OF THE WEEK IS A LOW PRESSURE SYSTEM WHICH MOVES THROUGH THE SOUTHERN PLAINS ON SATURDAY...THEN LIFTS NE THROUGH THE TENNESSEE VALLEY AND INTO THE MID-ATLANTIC STATES BY MONDAY. THIS STORM SHOULD PASS FAR ENOUGH SOUTH AND EAST OF THE REGION TO PREVENT ANY SIGNIFICANT PCPN DEVELOPMENT OVER C/NE WI. HOWEVER...LOW-LEVEL CYCLONIC FLOW AND THE PRESENCE OF THE BROAD UPPER TROF COULD BRING SCT LIGHT SNOW SHOWERS OR FLURRIES AT TIMES. FOR NOW...WILL MAINLY BE CARRYING SLIGHT CHC POPS FROM THE LATE WEEKEND THROUGH MIDWEEK. H8 TEMPS WILL NOT VARY MUCH OVER THE PERIOD...WITH MOST OF THE MEDIUM RANGE MODELS FORECASTING -8 TO -12 C. THIS SHOULD CONTINUE THE TREND OF BELOW NORMAL TEMPERATURES FOR THE NEXT WEEK...WITH LOWS IN THE TEENS AND LOWER 20S...AND HIGHS IN THE 30S. && .AVIATION...M000 TO 3000 FT CIGS AND A FEW SNOW FLURRIES NEAR THE MICHIGAN BORDER WILL TRY TO MOVE SOUTH A LITTLE BUT MOST PLACES WILL BE CLEAR TONIGHT. COLD AIR ALOFT WILL GENERATE MVFR CIGS AND SNOW SHOWERS WEDNESDAY AS AN UPPER LEVEL LOW MOVES SOUTH TOWARDS THE REGION. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS TAUNTON MA
204 AM EDT FRI MAR 22 2013 .SYNOPSIS... LOW PRESSURE MOVING SOUTHEAST OF NANTUCKET WILL BRING A PERIOD OF ACCUMULATING SNOW TO THE SOUTHEAST NEW ENGLAND COAST TONIGHT. OTHERWISE...MAINLY DRY BUT CHILLY WEATHER FOR LATE MARCH WILL CONTINUE THROUGH MOST OF NEXT WEEK. WILL HAVE TO KEEP A CLOSE EYE ON A MID ATLANTIC STORM FOR SUN NIGHT/MON. ODDS FAVOR THE BULK OF THE STORM PASSING TO OUR SOUTH...BUT STILL A LOW PROBABILITY IT TRENDS NORTH AND BRINGS MORE SNOW TO THE REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 200 AM UPDATE... HAS MENTIONED IN PREV AFD HAVE UPGRADED ADV TO A WARNING FOR SOUTHERN BRISTOL AND PLYMOUTH COUNTIES. HEAVY BAND OF SNOW THAT WAS SITUATED OVER THOSE COUNTIES HAS SHIFTED TO OVER COASTAL PLYMOUTH AND THE CANAL. EXPECT SNOW FALL RATES OF 1-2" PER HOUR AND VSBYS REDUCED TO BELOW ONE HALF OF A MILE. ROADS WILL BECOME QUICKLY SNOW COVERED. AM CONSIDERING UPGRADING THE WARNING ACROSS EASTERN PLYMOUTH AND BARNSTABLE COUNTIES. LATEST WEBCAMS SHOW SNOW COVERED ROADS AND HVY SNOW FALL WITHIN THE BANDS. ALTHOUGH HAVE NOT RECEIVED ANY REPORTS...WOULD NOT BE SURPRISED IF OVER 6 INCHES WILL BE REPORTED BY MORNING. IRONICALLY THE GFS MODEL HAS BEEN HANDLING THIS MESOSCALE FEATURE BETTER THAN THE HI-RES AND THE NAM. THE HRRR IS ALSO DOING FAIRLY WELL. IN FACT THE NAM DOESNT EVEN HAVE QPF FOR SE MASS RIGHT NOW! THE 00Z MODELS ARE STILL SHOWING A GOOD AMOUNT OF LIFT AND MOISTURE WITHIN THE SNOWGROWTH ZONE INTO THE MORNING SO HAVE EXTENDED THE HAZARDS. DO NOT SEE ANY LARGE FEATURES THAT WILL PUSH THESE BANDS OUT OF THE AREA ANY TIME SOON. INTERESTING TO SEE THAT 850MB VAD WIND PROFILES ARE SHOWING GOOD CONVERGENCE WHERE THE BAND HAS SET UP. BANDS WILL CONTINUE TO MOVE IN A MORE NNE DIRECTION TO FOLLOW THE MID-LEVEL FLOW. EXPECT A SLOW MORNING COMMUTE TO AREAS WITHIN THE HAZARDS RIGHT NOW. ALTHOUGH FORECASTING 4-8 INCHES...ISOLATED HIGHER AMOUNTS ARE POSSIBLE. THIS IS THE STRUGGLE OF TRYING TO PINPOINT THE EXACT LOCATION OF THE BANDING FEATURE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... MID LEVEL TROUGH STAYS PRETTY WELL PUT OVER THE NORTHEASTERN U.S. THROUGH FRIDAY. THIS...IN COMBINATION WITH THE SURFACE LOW IN THE MARITIMES WILL ALLOW FOR SOME FLURRIES AND ISOLATED LIGHT SNOW SHOWERS TO LINGER OVER THE CAPE AND ISLANDS AS WELL AS START UP ACROSS THE NORTHWESTERN ZONES LATER IN THE AFTERNOON. THESE SHOULD START TO COME TO AN END OVERNIGHT AS THE MID LEVEL LOW AND SURFACE LOW LIFT TO THE NORTHEAST TAKING THE LIFT AND MOISTURE WITH IT. TEMPERATURES WERE A BLEND OF BIAS CORRECTED MOS...WITH HIGH TEMPS REACHING THE MID TO UPPER 30S TO LOW 40S AND LOW TEMPS IN THE 20S. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGHLIGHTS... * UNSEASONABLY CHILLY WEATHER THROUGH NEXT WEEK * NEED TO KEEP A CLOSE EYE ON A MID ATLANTIC STORM SUN NIGHT/MON DETAILS... THE OVERALL PATTERN WILL CONTINUE TO FEATURE A NEGATIVE AO/NAO WELL INTO NEXT WEEK. THIS WILL RESULT IN LOWER THAN AVERAGE HEIGHT FIELDS AND IN TURN BELOW NORMAL TEMPS IN OUR REGION. MUCH OF THE PERIOD WILL FEATURE DRY NORTHWEST FLOW...SO THE STRONG MARCH SUN SHOULD STILL BE ENOUGH TO PUSH HIGHS INTO THE UPPER 30S TO MIDDLE 40S MUCH OF THE TIME. THE LATEST MEX GUIDANCE APPEARS TOO MILD THOUGH AS IT OFTEN TRENDS MORE TOWARDS CLIMATOLOGY IN THE LATER PERIODS. THE MAIN THING TO WATCH IS THE TRACK OF A MID ATLANTIC STORM SUNDAY NIGHT INTO MONDAY. MOST OF THE GUIDANCE HAS BEEN IN GOOD AGREEMENT THAT THE MAIN AFFECTS FROM THIS STORM WILL PASS SOUTH OF OUR REGION. THIS A RESULT OF VERY STRONG HIGH LATITUDE BLOCKING AND THE CLOSED UPPER LEVEL LOW NEAR THE CANADIAN MARITIMES. HOWEVER...THIS STORM IS STILL ABOUT 4 DAYS AWAY AND IT WOULDN/T TAKE MUCH OF A NORTHWARD ADJUSTMENT TO GET US INTO AT LEAST SOME OF THE PRECIPITATION SHIELD. IF THIS WERE TO OCCUR...MOST OF THE REGION WOULD BE COLD ENOUGH FOR A SNOW EVENT. SO WHILE ODDS CURRENTLY FAVOR MORE OF A MISS/GLANCING BLOW TO THE SOUTH...THERE REMAINS A LOW PROBABILITY FOR ACCUMULATING SNOW SUNDAY NIGHT INTO MONDAY. LOW POPS WERE INCLUDED IN THE FORECAST TO ACCOUNT FOR THIS POSSIBILITY. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE EARLY THIS MORNING AND HIGH CONFIDENCE AFTERWARDS. MVFR TO IFR CONDITIONS ARE EXPECTED IN BANDS OF MODERATE TO HEAVY SNOW SHOWERS ACROSS SOUTHEAST MA EARLY THIS MORNING. EXPECT IMPROVING CONDITIONS BY THE MID-MORNING HOURS. VFR CONDITIONS WILL PERSIST ELSEWHERE. DIURNAL CU WILL DEVELOP TOMORROW AS NW WINDS MAY GUST TO 20-25 KTS BY THE AFTERNOON...LASTING THROUGH THE OVERNIGHT HOURS. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY AND SUNDAY...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS. NORTHWEST WIND GUSTS OF 25 TO 35 KNOTS EXPECTING DURING THE DAY SAT...BUT MUCH LESS WIND ON SUN. SUNDAY NIGHT AND MONDAY...LOW CONFIDENCE. MVFR-IFR CONDITIONS IN SNOW WOULD OCCUR ONLY IF STORM ENDS UP TRACKING FURTHER NORTH THAN CURRENT MODELS INDICATE. TUESDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS. && .MARINE... MODERATE TO HIGH CONFIDENCE THROUGH FRIDAY NIGHT. SEAS BUILD WITH THE PASSAGE OF A SURFACE LOW PRESSURE SOUTH AND EAST OF THE COASTAL WATERS. 5 TO 6 FOOT SEAS ARE EXPECTED ON THE OUTER WATERS BY FRIDAY MORNING AND 6 TO 8 FOOT SEAS BY FRIDAY NIGHT. NORTHEASTERLY WINDS WILL SHIFT TO THE WEST AS THEY INCREASE TO AROUND 25 KTS. SMALL CRAFT ADVISORIES ARE UP FOR THE SOUTHEASTERN OUTER WATERS THROUGH FRIDAY AFTERNOON. THESE WILL LIKELY NEED TO BE EXTENDED INTO FRIDAY NIGHT FOR MORE OF THE WATERS. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY AND SATURDAY NIGHT...HIGH CONFIDENCE IN STRONG SCA WIND GUSTS FROM THE NORTHWEST IN THE COLD AIR ADVECTION PATTERN. LOW PROBABILITY FOR A PERIOD OF MARGINAL GALE FORCE WIND GUSTS. SUNDAY...MODERATE TO HIGH CONFIDENCE. WINDS AND SEAS SUBSIDING...BUT LINGERING SCA LIKELY NEEDED FOR AT LEAST THE MORNING. SUNDAY NIGHT AND MONDAY...MODERATE CONFIDENCE. SHOULD SEE AT LEAST SCA NORTHEAST WIND GUSTS DEVELOP LATE SUN NIGHT/MON AS LOW PRESSURE PASSES SOUTH OF THE WATERS. THERE IS A LOW PROBABILITY FOR A PERIOD OF GALE FORCE WIND GUSTS IF THE STORM TRACK ENDS UP FURTHER NORTH THAN CURRENT MODELS INDICATE. TUESDAY...MODERATE CONFIDENCE. MARGINAL NORTHWEST SCA WIND GUSTS OF 20 TO 25 KNOTS ARE POSSIBLE IN THE COLD AIR ADVECTION PATTERN BEHIND THE DEPARTING LOW PRESSURE SYSTEM. && .CLIMATE... NORMAL HIGH TEMP/NORMAL LOW TEMP BOS 47 / 32 BDL 50 / 29 PVD 49 / 31 ORH 45 / 28 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR MAZ018-019-022-023. WINTER STORM WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR MAZ020-021. NH...NONE. RI...WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR RIZ007. MARINE...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ254>256. && $$ SYNOPSIS...FRANK/RLG NEAR TERM...DUNTEN SHORT TERM...RLG LONG TERM...FRANK AVIATION...FRANK/DUNTEN MARINE...FRANK/RLG CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
431 AM CDT FRI MAR 22 2013 ...UPDATED LONG TERM SECTION... .SYNOPSIS... ISSUED AT 252 AM CDT FRI MAR 22 2013 THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID LEVELS EXHIBITES COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC LIFT. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 252 AM CDT FRI MAR 22 2013 NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND 18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND. WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND INTO TONIGHT. WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 429 AM CDT FRI MAR 22 2013 WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL GET THE BRUNT OF THE STORM. 400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE 32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY 83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO 25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR. THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY 283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL. GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700 WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST. THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST OF THE DAY. UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS 60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE END THE MONTH OF MARCH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 110 AM CDT FRI MAR 22 2013 RAPIDLY DEVELOPING STRATUS WILL LIKELY SOON BECOME WIDESPREAD ACROSS MOST OF CENTRAL AND SOUTHWEST KANSAS. PERIODS OF RAIN/SNOW SHOWERS ARE LIKELY AT KHYS THROUGH AROUND 10Z AS AN UPPER LEVEL SHORTWAVE LIFTS THROUGH THE REGION. AS THE PRECIPITATION CLEARS BY 12Z AND STRONG INSOLATION DIMINISHES THE STRATUS, VFR CONDITIONS ARE EXPECTED THROUGH EARLY FRIDAY EVENING WHEN THE EFFECTS OF THE NEXT SYNOPTIC SCALE STORM BEGIN TO DEVELOP AS SCATTERED SHOWERS AND DEVELOPING STRATUS ONCE AGAIN. && .PRELIMINARY POINT TEMPS/POPS... DDC 52 35 35 23 / 10 80 90 90 GCK 52 33 33 21 / 10 90 90 90 EHA 56 37 37 21 / 20 90 90 80 LBL 56 38 38 23 / 10 80 90 80 HYS 48 30 31 23 / 10 90 90 90 P28 52 36 38 28 / 10 50 90 80 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR KSZ030-031-043>046-061>066. WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY FOR KSZ074>081-084>090. && $$ SYNOPSIS...RUSSELL SHORT TERM...RUSSELL LONG TERM...UMSCHEID AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS WICHITA KS
342 AM CDT FRI MAR 22 2013 .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 341 AM CDT FRI MAR 22 2013 FORECAST HIGHLIGHTS FOCUS AROUND FREEZING DRIZZLE CHANCES THIS MORNING...WITH POTENTIALLY HEAVY SNOW SATURDAY-SATURDAY NIGHT. A FAST MOVING SHORTWAVE APPROACHING FROM THE WEST IN CONCERT WITH A SUBTLE 850-700MB TROUGH/CONVERGENCE ZONE AND SATURATED LOW-LEVELS IS RESULTING IN PATCHY LIGHT FREEZING DRIZZLE EARLY THIS MORNING OVER GENERALLY THE NORTHEAST 1/4 OF KS. GIVEN LATEST OBSERVATIONS AND SHORT-TERM GUIDANCE...ANTICIPATE THIS ACTIVITY WILL AFFECT FAR NORTHEAST/EAST PORTIONS OF THE FORECAST AREA EARLY THIS MORNING...GENERALLY EAST/NORTHEAST OF A LINE EXTENDING FROM SALINA-HILLSBORO-EUREKA-CHANUTE. GIVEN RELATIVELY WARM PAVEMENT TEMPERATURES...NOT ANTICIPATING WIDESPREAD PROBLEMS ON ROADS...ALTHOUGH BRIDGE DECKS AND OTHER ELEVATED SURFACES MAY BE SLICK. NOT ANTICIPATING ISSUING A WINTER WEATHER ADVISORY. ADDITIONALLY...PATCHY LIGHT SNOW WILL AFFECT PRIMARILY CENTRAL/EAST-CENTRAL KS THROUGH EARLY TO MID MORNING...ASSOCIATED WITH SATURATED MID-LEVELS AHEAD OF APPROACHING SHORTWAVE. SNOW ACCUMULATIONS WILL LIKELY REMAIN WELL UNDER ONE-HALF INCH. FURTHERMORE...LOOSELY ORGANIZED BAND OF SHOWERS/THUNDERSTORMS OVER NORTHERN OK...ASSOCIATED WITH 850-700MB WARM/MOIST ADVECTION...WILL LIKELY REMAIN SOUTH OF THE KS/OK BORDER AS ACTIVITY SHIFTS EAST EARLY THIS MORNING. ATTENTION THEN TURNS TO POTENTIAL WINTER STORM TO AFFECT THE REGION SATURDAY-SATURDAY NIGHT...AS A SHORTWAVE CURRENTLY OVER THE PACIFIC NORTHWEST DIVES SOUTHEAST AND STRENGTHENS. DESPITE SOME MINOR TO MODEST DIFFERENCES IN TRACK AND INTENSITY...MODELS HAVE BEEN TRENDING INTO BETTER AGREEMENT. IF THERE IS AN OUTLIER...IT`S THE SLIGHTLY FASTER AND NOT QUITE AS AMPLIFIED GFS SOLUTION...WITH ALL OTHER MODELS A TAD SLOWER AND DEEPER. MODEL CONSENSUS STILL BULLSEYES CENTRAL/EAST-CENTRAL KS WITH THE GREATEST ACCUMULATIONS. GIVEN EXPECTED STRONG FRONTOGENESIS...COUPLED FORCING AND DECENT SNOW GROWTH ZONE LAPSE RATES...EXPECTING 4-7 INCHES GENERALLY NORTH OF HIGHWAY 50. FURTHER SOUTH ACROSS SOUTH-CENTRAL/SOUTHEAST KS...A RAIN/SNOW MIX WILL CUT INTO SNOW AMOUNTS...WITH ACCUMULATIONS OF 1-4 INCHES...LEAST NEAR THE KS/OK BORDER. OTHER THAN PATCHY POCKETS OF SLEET...PREDOMINANT PRECIPITATION TYPES WILL LIKELY EITHER BE RAIN OR SNOW GIVEN EXPECTED THERMAL PROFILES. IT SHOULD BE SAID THERE DOES REMAIN SOME UNCERTAINTY...NAMELY THE NAM SOLUTION...WHICH WOULD SUGGEST A SWATCH OF HEAVIER SNOW ALONG THE TURNPIKE AND JUST SOUTHEAST SATURDAY NIGHT. GIVEN ITS TENDENCY FOR EMBELLISHMENT BEYOND 36 HOURS...WILL NOT BITE JUST YET. HEADLINES-WISE...WILL EXPAND WINTER STORM WATCH A BIT FURTHER EAST TO INCLUDE HARVEY-MARION-CHASE COUNTIES. GIVEN LATEST 00Z ECMWF NOT TRENDING SOUTH...WILL NOT EXPAND WATCH INTO SOUTHERN KS. ALSO...GIVEN STILL SOME WOBBLE IN THE STORM`S TRACK AND INTENSITY...WILL LET THE DAY SHIFT MAKE THE CALL ON WINTER STORM WARNINGS AND ADVISORIES. SNOW SHOULD COME TO AN END SOMETIME LATE SATURDAY NIGHT OR SUNDAY MORNING OVER EASTERN KS. ADK .LONG TERM...(MONDAY THROUGH THURSDAY NIGHT) ISSUED AT 341 CDT FRI MAR 22 2013 A COLD EARLY TO MID WEEK IS ANTICIPATED...AS LONGWAVE TROUGHING PERSISTS ACROSS THE CENTRAL AND EASTERN CONUS. GFS/ECMWF CONSENSUS SUGGESTS BUILDING HEIGHTS/THICKNESS BY MID TO LATE WEEK...WHICH SHOULD ALLOW TEMPERATURES TO AT LEAST CLIMB INTO THE 50S...WHICH WOULD GET THEM CLOSER TO NORMAL IN THE 50S-60S. ADK && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1145 PM CDT THU MAR 21 2013 AVIATION CONCERNS REMAIN LOW CIGS ALONG WITH SOME FREEZING DRIZZLE POTENTIAL TONIGHT INTO FRI MORNING. MVFR CIGS CONTINUE TO WORK WEST AND ARE JUST ABOUT READY TO GET INTO KRSL. CURRENT THINKING IS THAT THESE CIGS WILL CONTINUE TO LOWER OVERNIGHT WITH WIDESPREAD IFR CIGS LIKELY AFTER 08Z. THE DRIZZLE THAT HAS OCCURRED SO FAR OVER NORTHEAST KS AND NW MO IS IN AN AREA OF LOW LEVEL ISENTROPIC LIFT ALONG THE 285K SURFACE. IN FACT THE LATEST RUC ANALYSIS IS SHOWING A COLD POCKET ALONG THIS SURFACE RIGHT OVER FAR NORTHEAST KS WHICH IS LIKELY CONTRIBUTING TO THE FREEZING DRIZZLE. AT THIS TIME FEEL THAT LOCATIONS NORTHEAST OF A MCPHERSON TO EL DORADO TO CHANUTE LINE WILL HAVE THE BEST CHANCE TO GET IN ON SOME OF THIS FREEZING DRIZZLE GENERALLY AFTER 10Z. THEREFORE KCNU IS THE TAF SITE WITH THE BEST CHANCE TO SEE SOME OF THIS EARLY FRI MORNING. BY AROUND 15-16Z CIGS WILL START TO CLIMB ABOVE IFR LEVELS FOR LOCATIONS ALONG AND WEST OF I-135 WHILE KCNU STAYS SOCKED-IN INTO THE AFTERNOON HOURS. LAWSON && .FIRE WEATHER... ISSUED AT 341 AM CDT FRI MAR 22 2013 BELOW NORMAL TEMPERATURES THROUGH AT LEAST EARLY TO MID NEXT WEEK ALONG WITH THE POTENTIAL FOR WIDESPREAD PRECIPITATION SATURDAY AND SATURDAY NIGHT SHOULD CREATE RELATIVELY LOW FIRE DANGER OVER THE NEXT SEVERAL DAYS. ADK && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 51 34 37 28 / 10 40 60 80 HUTCHINSON 50 32 36 27 / 10 50 70 80 NEWTON 49 32 34 26 / 10 40 70 80 ELDORADO 48 33 37 28 / 20 30 60 80 WINFIELD-KWLD 51 35 40 29 / 10 30 60 80 RUSSELL 49 31 33 23 / 10 50 90 90 GREAT BEND 52 31 34 24 / 0 50 80 90 SALINA 48 31 35 27 / 20 40 80 90 MCPHERSON 49 32 34 26 / 10 40 80 90 COFFEYVILLE 47 35 44 31 / 20 20 60 80 CHANUTE 43 33 41 29 / 30 10 60 80 IOLA 42 32 41 28 / 30 10 60 80 PARSONS-KPPF 46 35 43 30 / 20 10 60 80 && .ICT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ032-033-047>053-067-068. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1145 PM CDT THU MAR 21 2013 .UPDATE... ISSUED AT 1015 PM CDT THU MAR 21 2013 UPDATED TO MAKE SOME MINOR TWEAKS TO GRIDS. WATER VAPOR IMAGERY CONTINUES TO SHOW THE UPPER WAVE SLIDING OVER WEST-CENTRAL KS. MEANWHILE EAST SURFACE WINDS CONTINUE TO ADVECT HIGHER LOW LEVEL MOISTURE AND LOW CIGS ACROSS THE AREA. LOW LEVEL ISENTROPIC LIFT IS RESULTING IN SOME DRIZZLE OVER NORTHEAST KS AND WESTERN MISSOURI. WOULD EXPECTED THIS AREA OF DRIZZLE TO EVENTUALLY EXPAND OVER SE PORTIONS OF THE FORECAST AREA. THE CHALLENGE TONIGHT WILL BE KEEPING AN EYE ON SURFACE TEMPS FOR POSSIBLE FREEZING DRIZZLE. THEY SHOULD HOVER VERY CLOSE TO OR JUST ABOVE FREEZING WITH A POSSIBLE DECREASE AS SITES START TO WET BULB DOWN SLIGHTLY. THE PRECIP OVER NW KS SHOULD ALSO IMPACT THE AREA AFTER 06Z AND MAY BRING A MIX OF SOME SNOW OR LIGHT RAIN. WHILE CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO RUN WITH AN ADVISORY FOR FREEZING DRIZZLE...WOULD NOT BE SURPRISED TO SEE A SMALL SHORT-LIVED ONE OUT FOR THE MORNING COMMUTE. LAWSON && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 330 PM CDT THU MAR 21 2013 TONIGHT-FRI: LOTS OF DRY AIR IN THE LOWEST 2-3K FEET OF THE ATMOSPHERE HAS LIMITED PRECIP REACHING THE GROUND TO THE EXTREME ERN HALF OF THE FORECAST AREA. BUT MID LEVEL LIFT HAS BEEN SLOW TO MOVE INTO THE AREA...WITH LOWER LAYER LIFT INCREASING INTO THE EVENING HOURS ACROSS MAINLY ACROSS SRN/SERN KS. AS THIS LIFT INCREASES...WILL SEE THE LOWER LAYERS SATURATE ENOUGH FOR AT LEAST A DRIZZLE CHANCE ACROSS CENTRAL AND SRN KS. SFC TEMPS CLOSE TO FREEZING ALONG OR NORTH OF HIGHWAY 50 MAY LEAD TO SOME VERY LIGHT FREEZING DRIZZLE. FURTHER TO THE NORTH ALONG I-70 COULD SEE SOME LIGHT RAIN OR SLEET MIX IN WITH THE FREEZING DRIZZLE AS WELL. SO WILL CONTINUE THIS MENTION OVERNIGHT. NOT THINKING THIS WINTRY MIX WILL LEAD TO ANY TRAVEL PROBLEMS AS WARM GROUND TEMPS WILL LEAD TO FREEZING ONLY ON ELEVATED SURFACES. AFTER THIS INITIAL LIFT MOVES EAST...LOW LEVEL MOISTURE WILL REMAIN SOMEWHAT HIGH INTO FRI FOR SOME LOW CLOUDS. BUT FRI WILL BE THE LULL BETWEEN THIS EVENINGS SYSTEM AND A MUCH MORE SIGNIFICANT SYSTEM FOR SAT. SO ACTUALLY COULD SEE SOME BREAKS IN THE CLOUDS ON FRI...WITH SUNSHINE ACTUALLY WARMING MAX TEMPS IN THE 50S FOR MOST AREAS WEST OF INTERSTATE 135. SAT-SUN: MODELS ARE COMING TOGETHER ON A MORE SIGNIFICANT STORM SYSTEM EXPECTED TO MOVE OUT OF THE ROCKIES INTO THE PLAINS ON SAT. THIS SYSTEM WILL START OUT WITH BETTER LOW LEVEL MOISTURE THAN TODAYS SYSTEM...WITH WARM ADVECTION AND MOISTURE TRANSPORT AHEAD OF THIS SHORTWAVE LEADING TO AN INCREASING CHANCE OF WIDESPREAD SNOW OVER MOST OF CEN KS ON SAT. SATURATION/LIFT INCREASES IN THE MAIN SNOW GROWTH REGION BY AROUND NOON SAT ACROSS CEN KS. SFC TEMPS MAY START OUT JUST A LITTLE ABOVE FREEZING IN CEN KS...BEFORE WET BULB EFFECTS DROP TEMPS ENOUGH FOR A HEAVY WET SNOW TO BEGIN ACCUMULATING BY LATE SAT AFTN. THIS LIFT AND SATURATION LASTS THE LONGEST OVER MOST OF CEN KS...FOR MODERATE SNOW ACCUMULATIONS BY SAT EVE...WITH SOME AREAS IN CEN KS HAVING THE POTENTIAL TO SEE 4 TO 7 INCHES OF ACCUMULATION. STRONG GUSTY N-NW WINDS WILL ALSO BEGIN TO RAMP UP AS WELL FOR SAT AFTN/EVE...SO WITH POSSIBLE TRAVEL IMPACTS ACROSS CEN KS...WILL HOIST A WINTER STORM WATCH FOR CEN KS. A LITTLE MORE UNCERTAIN ON HOW FAR SOUTH TO TAKE THIS WATCH...AS A MIX OF RAIN/SNOW WILL CHANGEOVER TO ALL SNOW ACROSS SOUTH CEN KS AS WELL FOR SAT EVE. THINK INITIAL SNOWFALL MAY MELT AS IT FALLS WHICH WILL CUT DOWN ON SNOW TOTALS FOR AREAS NEAR KICT/EL DORADO AND NEWTON. COULD STILL SEE ACCUMULATIONS AROUND 3 INCHES IN THIS AREA AS WELL...AS BEST COMBINATION OF LIFT/SATURATION MOVES ACROSS SOUTH CEN KS BETWEEN 00-06Z/SUN. WOULD NOT BE SURPRISED TO SEE CEN KS UPGRADED TO A WARNING WITH LATER SHIFTS WITH A POSSIBLE ADVISORY FOR AREAS BETWEEN HIGHWAY 50 AND 54. KETCHAM .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 327 PM CDT THU MAR 21 2013 AFTER THE WEEKEND SYSTEM MOVES OUT OF THE AREA...A BROAD TROUGH LOOKS TO REMAIN OVER THE NORTHERN PLAIN FOR MON INTO TUE...WITH A CANADIAN HIGH PRESSURE AREA SETTLING OVER THE AREA. THIS WILL LEAD TO TEMPS REMAINING WELL BELOW NORMAL FOR THE START OF THE WEEK...WITH BOTH THE GFS/ECMWF SHOWING 850H TEMPS OF MINUS 10. SO EXPECT TEMPS TO STRUGGLE ACROSS THE AREA FOR MON/TUE...WITH TEMPS EXPECTED TO BE 15 TO 20 DEGREES BELOW NORMAL. EXPECT A SLOW WARMING TREND TOWARDS WED/THU WHICH WILL LEAD TO TEMPS CLOSER TO CLIMO NORMS..WITH DRY CONDITIONS EXPECTED. KETCHAM && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1145 PM CDT THU MAR 21 2013 AVIATION CONCERNS REMAIN LOW CIGS ALONG WITH SOME FREEZING DRIZZLE POTENTIAL TONIGHT INTO FRI MORNING. MVFR CIGS CONTINUE TO WORK WEST AND ARE JUST ABOUT READY TO GET INTO KRSL. CURRENT THINKING IS THAT THESE CIGS WILL CONTINUE TO LOWER OVERNIGHT WITH WIDESPREAD IFR CIGS LIKELY AFTER 08Z. THE DRIZZLE THAT HAS OCCURRED SO FAR OVER NORTHEAST KS AND NW MO IS IN AN AREA OF LOW LEVEL ISENTROPIC LIFT ALONG THE 285K SURFACE. IN FACT THE LATEST RUC ANALYSIS IS SHOWING A COLD POCKET ALONG THIS SURFACE RIGHT OVER FAR NORTHEAST KS WHICH IS LIKELY CONTRIBUTING TO THE FREEZING DRIZZLE. AT THIS TIME FEEL THAT LOCATIONS NORTHEAST OF A MCPHERSON TO EL DORADO TO CHANUTE LINE WILL HAVE THE BEST CHANCE TO GET IN ON SOME OF THIS FREEZING DRIZZLE GENERALLY AFTER 10Z. THEREFORE KCNU IS THE TAF SITE WITH THE BEST CHANCE TO SEE SOME OF THIS EARLY FRI MORNING. BY AROUND 15-16Z CIGS WILL START TO CLIMB ABOVE IFR LEVELS FOR LOCATIONS ALONG AND WEST OF I-135 WHILE KCNU STAYS SOCKED-IN INTO THE AFTERNOON HOURS. LAWSON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 33 50 36 39 / 30 10 30 60 HUTCHINSON 31 52 34 36 / 30 10 30 70 NEWTON 29 48 34 35 / 30 10 30 60 ELDORADO 30 49 36 39 / 40 20 20 60 WINFIELD-KWLD 33 54 37 42 / 40 10 20 60 RUSSELL 29 51 31 33 / 30 10 50 80 GREAT BEND 31 54 33 34 / 30 10 50 80 SALINA 30 51 32 36 / 30 20 30 70 MCPHERSON 31 50 33 35 / 30 10 30 70 COFFEYVILLE 33 50 37 45 / 50 20 20 60 CHANUTE 30 48 35 41 / 50 20 20 60 IOLA 29 45 34 39 / 50 30 10 60 PARSONS-KPPF 31 48 37 44 / 50 20 20 60 && .ICT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON FOR KSZ032-033-047>051-067. && $$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1139 PM CDT THU MAR 21 2013 .UPDATE... ISSUED AT 1136 PM CDT THU MAR 21 2013 UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE. UPDATE ISSUED AT 850 PM CDT THU MAR 21 2013 FORECAST APPEARS TO BE ON TRACK...WITH NO CHANGES MADE TO SNOWFALL AMOUNTS OR ADVISORY AREAS. A BUFFER ZONE OF CHANCE POPS WAS EXPANDED A COUPLE OF COUNTIES TO THE EAST FOR TONIGHT...MAINLY ALONG A KMDH TO KPAH TO KHOP LINE. THIS WAS BASED MAINLY ON RUC MODEL DATA. THE 21Z RUC WAS MORE AGGRESSIVE THAN PREVIOUS RUNS IN BRINGING THE DEEP MOISTURE /AS INDICATED BY 1000 TO 500 MB MEAN RH/ EASTWARD. RADAR TRENDS SUPPORT THE RUC MODEL. WHATEVER PRECIP MAKES IT INTO THE AREA OF CHANCE POPS WILL BE INSIGNIFICANT...SINCE THE MODELS DECREASE THE DEEP MOISTURE FROM NORTHWEST TO SOUTHEAST LATE TONIGHT. ALSO...SURFACE TEMPS WILL BE AT OR ABOVE FREEZING MUCH OF THE NIGHT WHERE PRECIP OCCURS. .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 259 PM CDT THU MAR 21 2013 NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY. THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES. A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT. ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW. THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT. USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO NEW MADRID. MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30 POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN. IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 259 PM CDT THU MAR 21 2013 THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES IMPACTING THE WFO PAH FORECAST AREA. THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF THE BETTER PERFORMING MODELS ON WEDNESDAY/. WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY /BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7 AM CDT/ SUNDAY MORNING. THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS. MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A 1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/ AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE. FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION. AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE. THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME OF YEAR. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 259 PM CDT THU MAR 21 2013 NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY. THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES. A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT. ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW. THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT. USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO NEW MADRID. MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30 POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN. IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 259 PM CDT THU MAR 21 2013 THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES IMPACTING THE WFO PAH FORECAST AREA. THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF THE BETTER PERFORMING MODELS ON WEDNESDAY/. WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY /BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7 AM CDT/ SUNDAY MORNING. THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS. MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A 1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/ AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE. FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION. AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE. THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME OF YEAR. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1136 PM CDT THU MAR 21 2013 RADAR SHOWS SNOW SOUTH/WEST OF KCGI AND MODELS...FOR THE MOST PART...KEEP IT THERE. LOW VFR CIGS SHOULD SEE A SCATTERED MVFR DECK BECOME PREVAILING OVERNIGHT/TOWARD MORNING. THIS WILL TRANSLATE TO PADUCAH AS WELL...AND THEN FURTHER EAST TO KEVV/KOWB BY THE PLANNING PERIOD. TOWARD THE END OF THE EFFECTIVE VALID TIME...SOME LIGHT PCPN MAY DEVELOP KCGI/KPAH. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...WINTER WEATHER ADVISORY UNTIL 7 AM CDT FRIDAY FOR MOZ100-107>110- 114. IN...NONE. KY...NONE. && $$
AREA FORECAST DISCUSSION
NWS DULUTH MN
259 AM CDT FRI MAR 22 2013 .SHORT TERM...THROUGH SATURDAY. THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION TONIGHT INTO SATURDAY. THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING. THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA. THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F. TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT. A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN. HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS. .LONG TERM...SAT NIGHT THROUGH FRIDAY. THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE INTRODUCED BROADBRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT WEEK. BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST. LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH MID-WEEK. && .AVIATION... A STRATUS DECK WITH CEILINGS AROUND 2 KFT SEEN ON SATELLITE IMAGERY OVER ONTARIO...WILL PUSH SOUTH AND WEST INTO THE FORECAST AREA THROUGH DAYBREAK. THIS AREA OF LOW CLOUDS IS EXPECTED TO MAINLY AFFECT THE THE KINL AND KHIB TERMINALS WHERE HAVE ADDED A TEMPO FOR MVFR CIGS...THROUGH THE EARLY MORNING. ELSEWHERE...CLEAR SKIES AND VFR CIGS WILL PREVAIL WITH A BRIEF PERIOD OF LOWER VSBYS DUE TO LIGHT FG/BR POSSIBLE THROUGH 12Z. && .POINT TEMPS/POPS... DLH 31 15 32 17 / 10 10 10 10 INL 30 10 32 15 / 10 10 10 10 BRD 32 13 33 18 / 0 10 10 10 HYR 33 8 35 16 / 0 10 10 10 ASX 31 11 32 17 / 10 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MELDE LONG TERM....GRANING AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
109 AM CDT FRI MAR 22 2013 .AVIATION...06Z TAF ISSUANCE... CLOUDS LINGER OVER THE MN ARROWHEAD TOWARDS THE TWIN PORTS HOWEVER CEILINGS REMAIN VFR FOR THE MAJORITY OF THE SITES. EXPECT VFR TO PREVAIL THIS PERIOD ALTHOUGH A BRIEF PERIOD OF MVFR MAY DEVELOP OVER NRN/ERN TERMINALS. && PREV DISCUSSION... /ISSUED 308 PM CDT THU MAR 21 2013/ SHORT TERM.../NOW - FRIDAY/ AT 3PM/2000Z...THERE WAS A RIDGE OF HIGH PRESSURE OVER THE NORTHERN PLAINS AND SOUTHERN MINNESOTA. THE NORTHLAND HAD LIGHT NW WINDS DUE TO A LARGE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN UNITED STATES AND SOUTHEASTERN CANADA. MOST OF THE NORTHLAND HAD SUNNY TO MOSTLY SUNNY SKIES...BUT THERE WAS STILL SOME LINGERING LAKE EFFECT SNOW RELATED OVC CLOUDS OVER THE FAR EASTERN FORECAST AREA IN NW WISCONSIN. THE OVC CLOUDS WERE QUICKLY DIMINISHING AS THE WINDS WEAKENED OVER WESTERN LAKE SUPERIOR...CUTTING OFF THE MOISTURE SUPPLY. TEMPERATURES WERE IN THE LOWER TO UPPER 20S ACROSS THE NORTHLAND. TONIGHT...THE HIGH PRESSURE IN THE NORTHERN PLAINS WILL SLOWLY MOVE INTO THE NORTHLAND. THE NORTHLAND CAN EXPECT CLEAR TO MOSTLY CLEAR SKIES. THERE COULD BE SOME CLOUDS OVER THE TIP OF THE ARROWHEAD LATE TONIGHT. THE NAM AND RAP INDICATE SOME ENHANCED LOW LEVEL MOISTURE MOVING INTO THAT AREA...BUT LEANED ON A CLEAR FORECAST. THE MODEL GUIDANCE IS LIKELY MUCH TOO WARM CONSIDERING THE CLEAR SKIES AND VERY LIGHT WINDS EXPECTED FOR TONIGHT...SO UNDERCUT THE MODEL CONSENSUS BY SEVERAL DEGREES. OVERNIGHT LOWS WILL PROBABLY BE WELL INTO THE SINGLE DIGITS BELOW ZERO ACROSS MOST OF THE NORTHLAND. FRIDAY...THE HIGH PRESSURE OVER THE NORTHLAND WILL PROMOTE SUNNY TO MOSTLY SUNNY SKIES FOR AT LEAST THE MORNING. THERE COULD BE SOME INCREASING CLOUD COVER IN THE AFTERNOON BASED ON MODEL RH. HOWEVER...LEANED ON LESS CLOUD COVER SINCE THE MODELS SEEM TO BE EXAGGERATING THE POTENTIAL FOR CLOUD COVER. FRIDAY COULD VERY EASILY BE SUNNY ACROSS THE REGION...SO UPDATES MIGHT NEED TO BE MADE IN THE FUTURE. HIGH TEMPERATURES WILL LIKELY BE IN THE LOWER 30S. LONG TERM.../FRIDAY NIGHT - WEDNESDAY NIGHT/ CONTINUED QUIET WEATHER CONDITIONS THROUGH THE WEEKEND AND INTO THE MIDDLE OF NEXT WEEK WITH A NARROW RIDGE OF HIGH PRESSURE SITUATED OVER THE UPPER MIDWEST BETWEEN TWO SLOW MOVING UPPER LOWS. THE LOW TO THE WEST WILL EVENTUALLY UNDERCUT THE HIGH PRESSURE BY THIS WEEKEND. HOWEVER...THE ACTIVE PATTERN WILL REMAIN WELL TO THE SOUTH AND LEAVE THE NORTHLAND MOSTLY DEVOID OF PRECIPITATION. THE LOW LEVEL FLOW WILL BE FAVORABLE FOR A PERSISTENT E/NE WIND OFF LAKE SUPERIOR AND KEEP MUCH OF THE NORTHLAND UNDER THE INFLUENCE OF MOSTLY CLOUDY SKIES THROUGH THE WEEK. THE LACK OF SUN...COMBINED WITH A RELATIVELY COLD AIR MASS...850MB TEMPS -11 DEG C...WILL KEEP AFTERNOON HIGHS IN THE LOWER 30S AND OVERNIGHT LOWS IN THE TEENS. ROUGHLY 5-10 DEG BELOW AVERAGE. COULD SEE A FEW WEAK WAVES ROTATE WWD FROM THE UPPER TROUGH OVER ERN CANADA EARLY NEXT WEEK...BUT ONLY A SLIGHT CHANCE OF LIGHT SNOW IS POSSIBLE FROM THESE...WITH LITTLE TO NO SNOW ACCUMULATING. && .POINT TEMPS/POPS... DLH 12 32 16 32 / 10 10 10 10 INL 9 31 16 32 / 10 10 10 10 BRD 12 33 19 33 / 0 10 10 10 HYR 8 34 16 34 / 0 10 0 10 ASX 11 32 16 33 / 0 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS BISMARCK ND
133 AM CDT FRI MAR 22 2013 .DISCUSSION... MAIN UPDATES WERE TO ADJUST THE EASTWARD PROGRESSION OF THE SNOW BAND...ADJUST SKY COVER BASED ON LATEST SAT IMAGERY...AND TO ADJUST TEMPERATURES BASED ON LATEST OBSERVATIONS AND HR NEAR TERM MODEL DATA. OVERALL...UPDATES WERE MINOR WITH THE INHERITED FORECAST ON TRACK. LATEST RADAR IMAGERY/SURFACE OBSERVATIONS CONTINUE TO SHOW LIGHT SNOW BAND IN THE WEST WITH A SLIGHT MOVEMENT EASTBOUND. THE RAP MAINTAINS A VERY SLOW PROGRESSION EAST THROUGH FRIDAY AFTERNOON. WATER VAPOR IMAGERY SHOWS AN UPPER LOW BEGINNING TO FORM OVER NORTH CENTRAL MONTANA WITH A SURFACE LOW BASICALLY UNDERNEATH THE UPPER LOW FORMATION. THE SURFACE/UPPER AIR LOW IS FORECAST TO MOVE TO NEAR BAKER MONTANA BY 12Z FRIDAY. HENCE...EXPECT A CONTINUATION OF A FAIRLY SHARP DELINEATION FROM SNOW TO NO SNOW. STILL LOOKS LIKE MID TO LATE MORNING FOR THE SNOW TO ENTER THE BISMARCK AND MINOT AREAS. && .AVIATION... FOR THE 06Z FRIDAY TAF ISSUANCE...LIGHT SNOW WILL CONTINUE ACROSS THE WESTERN AERODROMES OF KISN/KDIK WITH MVFR/IFR CIGS AND VSBYS THROUGH FRIDAY AFTERNOON. LOW IFR/MVFR CIGS AT KBIS/KMOT ARE EXPECTED TO DEVELOP BY AROUND 09Z FRIDAY...WITH LIGHT SNOW AND MVFR VSBYS INITIATING BETWEEN 15Z AND 18Z FRIDAY. EXPECT SCT TO BKN MVFR CIGS AND PATCHY FOG AT KJMS BY AROUND 09Z FRIDAY...HOWEVER NO SNOWFALL OCCURRING UNTIL 22Z FRIDAY WITH MVFR CIGS COMMENCING AT THAT TIME. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH AVIATION...KS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
448 AM EDT FRI MAR 22 2013 .SYNOPSIS... AN UPPER LEVEL LOW OVER THE CANADIAN MARITIMES WILL REMAIN NEARLY STATIONARY INTO THE WEEKEND. A NEW STORM SYSTEM MOVING OUT OF THE OF THE MID- MISSISSIPPI VALLEY LATER THIS WEEKEND COULD BRING ANOTHER ROUND OF WINTRY PRECIPITATION TO THE REGION LATE SUNDAY NIGHT AND MONDAY. THE UNUSUAL BLOCKING PATTERN IN THE UPPER ATMOSPHERE IS EXPECTED TO KEEP THE PERSISTENT CHILL IN THE AIR RIGHT THROUGH THE END OF THE MONTH. && .NEAR TERM /THROUGH TODAY/... AT LEAST TWO LAKE EFFECT SNOW BANDS MANAGED TO MEANDER DOWN INTO THE CENTRAL MOUNTAINS OVER THE LAST SEVERAL HOURS LEAVING A FRESH COATING OF SNOW HERE AT THE OFFICE. OTHERWISE THE PATTERN HAS NOT CHANGED SIGNIFICANTLY...WITH MINOR DISTURBANCES BEING CHANNELED DOWN THE PERSISTENT COLD NW FLOW...OCCASIONALLY GIVING A POSITIVE BOOST TO THE VERTICAL MOTIONS. IT FINALLY LOOKS LIKE WE WILL SEE AT LEAST SOME MINOR IMPROVEMENT TODAY AS HEIGHTS ALOFT BEGIN TO RISE...INVERSION HEIGHTS COME DOWN AND LOW LEVEL WINDS BECOME MORE WESTERLY. HAVE NOT CHANGED THE TIMING OF THE LAKE SNOW ADVISORY SINCE IT LOOKS GOOD FOR THE SNOW SHOWERS TO BECOME LESS ORGANIZED AS WE GET DEEPER INTO THE DAY. TODAY`S HIGHS RANGING FROM THE MID 20S TO MID 40S FROM NW TO SE WILL BE SOME 10 TO 20 DEG BELOW NORMAL AS THIS UNUSUAL EARLY SPRING CHILL CONTINUES LOCKED IN OVER THE REGION. && .SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/... ANY LINGERING SNOW SHOWERS OVER NWRN AREAS WILL TAPER TO FLURRIES TONIGHT AS WE FINALLY START TO LOSE THE MOIST CYCLONIC FLOW ON THE BACK SIDE OF THE CANADIAN LOW. SKIES WILL SCATTER OUT OVER MOST OF THE FORECAST AREA...ALLOWING TEMPS TO FALL BACK INTO THE TEENS AND 20S...STILL WELL BELOW NORMAL FOR LATE MARCH. SATURDAY WILL REPRESENT A PERIOD OF BRIEF TRANQUILITY IN THE WAKE OF THE SLOW MOVING LOW THAT HAS BEEN KEEPING US CLOUDY-COLD AND UNSETTLED. HIGH PRESSURE WILL NOSE IN FROM THE LAKES WITH AT LEAST SOME DRIER WEATHER...THOUGH IT WILL NOT BE SIGNIFICANTLY WARMER THAN TODAY. ANY LINGERING FLURRIES WILL REMAIN VERY NEAR AND DOWNWIND OF LAKE ERIE. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... THE EXTENDED FORECAST WILL BE DOMINATED BY THE PROSPECTS OF YET MORE LATE WINTER/EARLY SPRING WINTRY WEATHER. MODELS ARE IN GOOD ACCORD WITH BRINGING A NEW TROF/UPPER LOW SWINGING AROUND UNDER THE NORTHERN CANADIAN BLOCKING HIGH...AND TRACKING IT EAST TOWARD THE MID ATLANTIC STATES. THE BIG QUESTIONS CENTER ON HOW CLOSE THE PRIMARY AND SECONDARY STORMS MANAGE TO GET TO THE LOCAL AREA AND HOW MUCH PRECIP THEY WILL PRODUCE. THE 00Z NAM IS VERY AGGRESSIVE AND IMPLIES WE COULD SEE WIDESPREAD SNOWS IN EXCESS OF 6 INCHES. THE GFS IS SLIGHTLY LESS AGGRESSIVE BUT STILL IMPLIES WARNING SNOWS FOR MUCH OF CENTRAL AND SOUTHERN PA. THE ECMWF IS MUCH DRIER...WITH ABOUT .25 TO LESS THAN .50" QPF OVER THE SRN HALF OF THE FCST AREA. THE SREF/GEFS BOTH SHOW A HIGH LIKELIHOOD OF AT LEAST .25"/12HR QPF...WITH THE CHANCES FOR .50"/12HR RUNNING IN THE 50-70% RANGE. MUCH BOTHERS ME ABOUT THE SREF/GEFS/NAM/GFS SCENARIOS. TRADITIONALLY WE DO NOT DO REAL WELL FROM THESE MILLER TYPE B REDEVELOPING LOWS UNLESS THE COASTAL LOW BECOMES THE BIG PRECIP PLAYER LOCALLY. IT SEEMS THE OPERATIONAL MODELS WANT MOST OF OUR PRECIP TO BE ASSOCIATED WITH THE DYING PRIMARY LOW AND I AM HARD PRESSED TO RECALL AN EVENT WHERE WE GOT MORE THAN 6" OF SNOW FROM SUCH A SET UP. IT SEEMS THE MOISTURE USUALLY RAPIDLY SHIFTS TO THE COASTAL LOW AND WE GET HIT HARD ONLY IF THE COASTAL TRACKS CLOSE ENOUGH...WHICH ALL BUT THE NAM ARE INDICATING WILL NOT HAPPEN. THE ENSEMBLES HAVE THE REQUISITE ANOMALOUS EASTERLY LOW LEVEL JET WHICH IS A CHECK MARK ON THE FAVORABLE SIDE OF THE LEDGER...BUT THE BEST PWATS NEVER GET ANYWHERE NEAR THE REGION...BEING RAPIDLY PINCHED OFF AND SHUNTED WELL OUT INTO THE ATLANTIC. OUR MOST RECENT STORM QPF WAS OFF BADLY...BY ABOUT HALF...PERHAPS BY THE NORTHERN EDGE OF THE PRECIP BEING ROBBED OF MOISTURE BY CONVECTION FURTHER SOUTH...AND I HAVE TO WONDER IF THIS WILL HAPPEN AGAIN AS THE MODELS DO INDICATE INSTABILITY SURGING NORTH TOWARD BOTH THE PRIMARY AND EXPECTED COASTAL LOWS. AT THIS POINT WE HAVE SNOW/RAIN INDICATED FOR SUNDAY INTO MONDAY...BUT CONFIDENCE IS VERY LOW AS TO QUANTITIES. AFTER THE STORM GOES BY...WE ONCE AGAIN LOCK IN UNDER A DEEP NW FLOW UNDER THE AMAZINGLY PERSISTENT NORTHERN CANADA/GREENLAND UPPER BLOCKING HIGH. THE GEFS SHOWS THIS RIDGE TO STAY IN PLACE THROUGH ABOUT MID WEEK WHEN IT FINALLY SHOWS SIGNS OF THE BLOCK BEGINNING TO BREAK DOWN. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... A COLD NORTHWEST FLOW WILL GATHER MOISTURE FROM THE GREAT LAKES AND DEPOSIT IT AS SNOW SHOWERS ACROSS THE ALLEGHENY MOUNTAINS TONIGHT AND FRIDAY. SOME OF THE HEAVIEST SNOW SHOWERS WITH IFR VSBYS WILL LIKELY OCCUR BTWN 04Z-08Z AT JST WITH PASSAGE OF A WEAK SFC TROUGH. LATEST RUC SHOWS A TONGUE OF HIGHER LOW LVL MOISTURE ALONG THIS BOUNDARY SAGGING SOUTH INTO THE LAUREL HIGHLANDS DURING THIS TIME PERIOD. DRYING...DOWNSLOPING FLOW SHOULD RESULT IN MUCH BETTER FLYING CONDS OVERNIGHT EAST OF THE MTNS. CAN/T RULE OUT BRIEF VSBY RESTRICTIONS OVERNIGHT AT AOO/UNV/IPT...WHILE CONDS AT MDT AND LNS APPEAR VERY LIKELY TO REMAIN VFR. EXPECT DIMINISHING -SHSN OVR THE W MTNS ON FRIDAY...AS INVERSION HEIGHTS LOWER WITH APPROACH OF SFC HIGH. STILL...OCNL MVFR CIGS/VSBYS REMAIN POSSIBLE AT BFD THRU FRI EVENING. AN INTENSE LOW PRES SYSTEM OVR THE CANADIAN MARITIMES WILL CONTINUE TO BUFFET THE AREA WITH A GUSTY WNW WINDS. ALTHOUGH THE GUSTS MAY DIMINISH A BIT OVERNIGHT...BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS ARND 25KTS DURING LATE FRI AM AND AFTERNOON. OUTLOOK... SAT...NO SIG WX EXPECTED. SUN...SNOW POSS LATE ACROSS THE SOUTH. MON...SNOW POSS...ESP SOUTH. TUE...SNOW POSS...ESP LAUREL HIGHLANDS. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT TODAY FOR PAZ004. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1137 PM CDT THU MAR 21 2013 .AVIATION... MVFR CIGS MOVING NORTH FROM THE GULF NOW AND ARE ALMOST AT TAF SITES...SO WILL START 06Z TAFS WITH MVFR. HAVE BACKED UP METROPLEX FROPA A BIT BASED ON NAM/RAP GUIDANCE...AND STILL FEEL CLOUDS WILL BE VERY SLOW TO BREAK FRIDAY AFTERNOON. WHEN THEY DO...CLEAR SKIES NORTH OF THE FRONT WITH LIGHT NORTHEAST FLOW WILL ALLOW TEMPERATURES TO COOL TO SATURATION LATE FRIDAY NIGHT AND HAVE INCLUDED IFR CIG/VSBY IN THE EXTENDED PORTION OF DFW TAF. ALL TAF SITES WILL LIKELY BE IFR BEFORE SUNRISE SATURDAY WITH WIDESPREAD FOG IN THE AREA. 84 && .UPDATE... WEAK MOISTURE CONVERGENCE AND LIMITED INSTABILITY PREVENTED THUNDERSTORM DEVELOPMENT ALONG THE DRY LINE THIS AFTERNOON/EARLY THIS EVENING. NOW WITH THE LOSS OF SURFACE HEATING...STORM CHANCES ALONG THE DRY LINE HAVE DECREASED SIGNIFICANTLY. THERE IS STILL A CHANCE OF SOME ELEVATED SHOWERS AND THUNDERSTORMS ACROSS THE NORTHERN HALF OF NORTH TEXAS WITH THE BEST STORM CHANCES ACROSS THE NORTHEAST ZONES JUST NORTH OF A WARM FRONT. FURTHER SOUTH...SOME WARM AIR ADVECTION SHOWERS ARE POSSIBLE...ESPECIALLY TOWARD MORNING. FOR THIS UPDATE...WE WILL LOWER EVENING POPS IN ALL ZONES AND MAKE SOME MINOR WIND/CLOUD COVER AND HOURLY TEMP/DEW POINT ADJUSTMENTS. 79 && .PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/ BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5 PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000 J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS. EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON AHEAD OF THE FRONT. THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO WARM TEMPERATURES THAN THE ECMWF. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 57 64 47 68 42 / 20 20 20 50 10 WACO, TX 62 71 50 74 42 / 10 20 20 50 5 PARIS, TX 48 58 45 58 37 / 50 30 20 50 20 DENTON, TX 51 60 45 65 39 / 30 20 20 40 10 MCKINNEY, TX 54 60 45 62 40 / 40 20 20 50 10 DALLAS, TX 58 64 48 68 43 / 20 20 20 50 10 TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10 CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10 TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5 MINERAL WELLS, TX 50 63 46 74 39 / 20 10 20 30 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
752 AM CDT FRI MAR 22 2013 ...UPDATED AVIATION SECTION... .SYNOPSIS... ISSUED AT 252 AM CDT FRI MAR 22 2013 THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID LEVELS EXHIBITS COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC LIFT. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 252 AM CDT FRI MAR 22 2013 NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND 18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND. WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND INTO TONIGHT. WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 429 AM CDT FRI MAR 22 2013 WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL GET THE BRUNT OF THE STORM. 400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE 32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY 83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO 25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR. THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY 283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL. GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700 WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST. THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST OF THE DAY. UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS 60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE END THE MONTH OF MARCH. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 746 AM CDT FRI MAR 22 2013 MAIN IMPACT ON AVIATION WILL BE THE DEVELOPMENT OF IFR/LIFR CEILINGS OVERNIGHT TONIGHT AS LOW PRESSURE DEVELOPS IN ADVANCE OF THE APPROACHING WINTER STORM. CEILINGS WILL DETERIORATE QUICKLY AROUND THE 08-10Z TIME FRAME AT DDC, GCK, AND HYS. PRECIPITATION IN THE FORM OF SNOW WILL DEVELOP SHORTLY AFTER DAYBREAK SATURDAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 52 35 35 23 / 10 80 90 90 GCK 52 33 33 21 / 10 90 90 90 EHA 56 37 37 21 / 20 90 90 80 LBL 56 38 38 23 / 10 80 90 80 HYS 48 30 31 23 / 10 90 90 90 P28 52 36 38 28 / 10 50 90 80 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR KSZ030-031-043>046-061>066. WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY FOR KSZ074>081-084>090. && $$ SYNOPSIS...RUSSELL SHORT TERM...RUSSELL LONG TERM...UMSCHEID AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1040 AM EDT FRI MAR 22 2013 .UPDATE... ISSUED AT 1040 AM EDT FRI MAR 22 2013 SOME SLIGHTLY DEEPER MOISTURE HAS MOVED INTO THE AREA...JUST ENOUGH TO ALLOW SOME SNOW TO MIX IN WITH THE FREEZING DRIZZLE DUE TO THE TOP OF THE CLOUD BEING AROUND -12C. HOWEVER...THIS IS EXPECTED TO ONLY LAST A FEW HOURS PER THE RAP SOUNDINGS. OTHERWISE...HAVE OPTED TO KEEP FREEZING DRIZZLE AROUND FOR MUCH OF THE DAY CLOSER TO LAKE SUPERIOR DUE TO THE PERSISTENT UPSLOPE FLOW THROUGH THE DAY AND SHALLOW MOISTURE. ANY SURFACES THAT ARE UNTREATED MAY BE SLIPPERY AT TIMES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 505 AM EDT FRI MAR 22 2013 UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM... SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE. BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON 00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR FZDZ. WILL PULL THE MENTION OF FZDZ. STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 505 AM EDT FRI MAR 22 2013 A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S. SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING. SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT. HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF INCH. TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 745 AM EDT FRI MAR 22 2013 LOW-LEVEL MOISTURE HAS RETURNED TO ALL THE TAF SITES THIS MORNING. EXPECT LOWER MVFR AND EVEN IFR CIGS THROUGH MORNING. MAY SEE -SHSN AND FZDZ AT TIMES THIS MORNING. FZDZ PATCHY ENOUGH AT THIS POINT TO KEEP OUT OF TAFS. EXPECT CLOUDS TO SCATTER OUT THIS EVENING AT IWD WITH DIFFLUENT LOW-LEVEL WINDS. OTHERWISE...PLAN ON BKN-OVC LOWER MVFR CIGS CMX AND SAW THROUGH END OF TAF PERIOD WITH PERSISTENT LIGHT NORTHERLY WINDS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 505 AM EDT FRI MAR 22 2013 HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS THAN 25 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...MRD SHORT TERM...JLA LONG TERM...JLB AVIATION...JLA MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
753 AM EDT FRI MAR 22 2013 .UPDATE... ISSUED AT 745 AM EDT FRI MAR 22 2013 FREEZING DRIZZLE HAS INDEED DEVELOPED...AFTER IT WAS REMOVED FROM FCST. SO IT GOES. ALSO SOME FLURRIES TOO SO IT APPEARS WE ARE RIGHT ON THE THRESHOLD FOR ICE NUCLEATION. RUC13 925MB TEMPS AROUND -8C SO THIS MAKES SOME SENSE. ADDED AREAS OF FREEZING DRIZZLE IN OVER HIGHER TERRAIN OF NW AND NCNTRL UPR MICHIGAN FOR NOW. ALSO PUT OUT SPECIAL WEATHER STATEMENT AND UPDATED SOCIAL MEDIA TO HIGHLIGHT HAZARD. FOR A START KEPT MENTION OF FZDZ THROUGH THE MORNING. WOULD THINK THERE MAY BE ENOUGH MIXING OUT OF NEAR SFC MOISTURE FOR FZDZ TO DISSIPATE BY AFTN. POSSIBLE THAT FZDZ COULD CONTINUE LONGER FOR UPSLOPE AREAS BUT NOT QUITE SURE SO WILL LET DAYSHIFT MAKE THAT ADJUSTMENT IF NEEDED. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 505 AM EDT FRI MAR 22 2013 UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM... SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE. BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON 00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR FZDZ. WILL PULL THE MENTION OF FZDZ. STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 505 AM EDT FRI MAR 22 2013 A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S. SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING. SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT. HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF INCH. TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 745 AM EDT FRI MAR 22 2013 LOW-LEVEL MOISTURE HAS RETURNED TO ALL THE TAF SITES THIS MORNING. EXPECT LOWER MVFR AND EVEN IFR CIGS THROUGH MORNING. MAY SEE -SHSN AND FZDZ AT TIMES THIS MORNING. FZDZ PATCHY ENOUGH AT THIS POINT TO KEEP OUT OF TAFS. EXPECT CLOUDS TO SCATTER OUT THIS EVENING AT IWD WITH DIFFLUENT LOW-LEVEL WINDS. OTHERWISE...PLAN ON BKN-OVC LOWER MVFR CIGS CMX AND SAW THROUGH END OF TAF PERIOD WITH PERSISTENT LIGHT NORTHERLY WINDS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 505 AM EDT FRI MAR 22 2013 HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS THAN 25 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SHORT TERM...JLA LONG TERM...JLB AVIATION...JLA MARINE...JLA
AREA FORECAST DISCUSSION
NWS DULUTH MN
924 AM CDT FRI MAR 22 2013 .UPDATE...PROGRESSIONS OF CLOUDS THROUGH THE ARROWHEAD AND ALONG THE INTERNATIONAL BORDER HAS SLOWED QUITE A BIT. THERE IS SOME EROSION OCCURRING ALONG THE LEADING EDGE. HAVE UPDATED THE SKY GRIDS TO ACCOUNT FOR THIS TREND. RAISED MAX TEMPS A BIT AS TEMPS ARE RECOVERING QUICKLY WHERE THERE IS FULL SUN...AND ESPECIALLY IN THE FORESTED AREAS IN NW WI. BROUGHT DEWPOINTS UP AS WELL FOR THE SAME REASON. && .PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAR 22 2013/ AVIATION...12Z TAF ISSUANCE. A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER 02Z. PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/ SHORT TERM...THROUGH SATURDAY. THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION TONIGHT INTO SATURDAY. THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING. THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA. THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F. TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT. A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN. HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS. LONG TERM...SAT NIGHT THROUGH FRIDAY. THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE INTRODUCED BROAD BRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT WEEK. BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST. LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH MID-WEEK. && .POINT TEMPS/POPS... DLH 30 15 32 17 / 0 10 10 10 INL 29 10 32 15 / 0 10 10 10 BRD 33 13 33 18 / 0 10 10 10 HYR 33 8 35 16 / 0 10 10 10 ASX 31 11 32 17 / 0 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...GSF
AREA FORECAST DISCUSSION
NWS DULUTH MN
652 AM CDT FRI MAR 22 2013 .AVIATION...12Z TAF ISSUANCE. A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER 02Z. && .PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/ SHORT TERM...THROUGH SATURDAY. THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION TONIGHT INTO SATURDAY. THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING. THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA. THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F. TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT. A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN. HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS. LONG TERM...SAT NIGHT THROUGH FRIDAY. THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE BECOMES A CLOSED H50 LOW IN THE VCNY OF MONTANA/WRN DAKOTAS BY SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE INTRODUCED BROADBRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT WEEK. BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST. LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH MID-WEEK. && .POINT TEMPS/POPS... DLH 31 15 32 17 / 10 10 10 10 INL 30 10 32 15 / 10 10 10 10 BRD 32 13 33 18 / 0 10 10 10 HYR 33 8 35 16 / 0 10 10 10 ASX 31 11 32 17 / 10 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
506 PM CDT FRI MAR 22 2013 .DISCUSSION... 307 PM CDT TONIGHT THROUGH SATURDAY... ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH FORECAST FOR SAT. OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING NORTHEASTERLY OFF OF THE LAKE OVERNIGHT. GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE MID/UPR 30S. SATURDAY NIGHT THROUGH SUNDAY NIGHT... LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES. GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA. ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME. AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN. THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN. WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S. CONFIDENCE IN TEMPERATURES...HIGH. CONFIDENCE IN SNOWFALL...MEDIUM. CONFIDENCE IN SNOW TIMING...MEDIUM. MONDAY THROUGH THURSDAY... 500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK OF THE EXTENDED. CONFIDENCE...HIGH. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT SATURDAY. RATZER/IZZI //DISCUSSION...UPDATED 18Z... SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON. CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS THE SOUTHERN PLAINS. OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON. SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM SYSTEM MOVES INTO THE LOWER OHIO VALLEY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 22Z... * LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING. RATZER/IZZI //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT. SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE AFTERNOON AND NIGHT. MONDAY...MVFR WITH A CHC OF SNOW SHOWERS. TUESDAY...SLT CHC OF SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. MTF && .MARINE... 225 PM CDT A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH TUESDAY. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WATCH...ILZ032-ILZ033-ILZ039...7 AM SUNDAY TO 7 AM MONDAY. IN...WINTER STORM WATCH...INZ010-INZ011-INZ019...7 AM SUNDAY TO 7 AM MONDAY. LM...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
336 PM CDT FRI MAR 22 2013 .DISCUSSION... 307 PM CDT TONIGHT THROUGH SATURDAY... ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH FORECAST FOR SAT. OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING NORTHEASTERLY OFF OF THE LAKE OVERNIGHT. GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE MID/UPR 30S. SATURDAY NIGHT THROUGH SUNDAY NIGHT... LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES. GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA. ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME. AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN. THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN. WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S. CONFIDENCE IN TEMPERATURES...HIGH. CONFIDENCE IN SNOWFALL...MEDIUM. CONFIDENCE IN SNOW TIMING...MEDIUM. MONDAY THROUGH THURSDAY... 500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK OF THE EXTENDED. CONFIDENCE...HIGH. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS. * POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT SATURDAY. RATZER //DISCUSSION...UPDATED 18Z... SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON. CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS THE SOUTHERN PLAINS. OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON. SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM SYSTEM MOVES INTO THE LOWER OHIO VALLEY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE ON LAKE BREEZE TIMING. * LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING. RATZER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT. SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE AFTERNOON AND NIGHT. MONDAY...MVFR WITH A CHC OF SNOW SHOWERS. TUESDAY...SLT CHC OF SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. MTF && .MARINE... 225 PM CDT A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH TUESDAY. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WATCH...ILZ032-ILZ033-ILZ039...7 AM SUNDAY TO 7 AM MONDAY. IN...WINTER STORM WATCH...INZ010-INZ011-INZ019...7 AM SUNDAY TO 7 AM MONDAY. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
309 PM CDT FRI MAR 22 2013 .DISCUSSION... 307 PM CDT TONIGHT THROUGH SATURDAY... ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH FORECAST FOR SAT. OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING NORTHEASTERLY OFF OF THE LAKE OVERNIGHT. GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE MID/UPR 30S. SATURDAY NIGHT THROUGH SUNDAY NIGHT... LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES. GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA. ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME. AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN. THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN. WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S. CONFIDENCE IN TEMPERATURES...HIGH. CONFIDENCE IN SNOWFALL...MEDIUM. CONFIDENCE IN SNOW TIMING...MEDIUM. MONDAY THROUGH THURSDAY... 500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK OF THE EXTENDED. CONFIDENCE...HIGH. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS. * POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT SATURDAY. RATZER //DISCUSSION...UPDATED 18Z... SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON. CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS THE SOUTHERN PLAINS. OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON. SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM SYSTEM MOVES INTO THE LOWER OHIO VALLEY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE ON LAKE BREEZE TIMING. * LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING. RATZER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT. SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE AFTERNOON AND NIGHT. MONDAY...MVFR WITH A CHC OF SNOW SHOWERS. TUESDAY...SLT CHC OF SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. MTF && .MARINE... 225 PM CDT A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH TUESDAY. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
239 PM CDT FRI MAR 22 2013 .DISCUSSION... 524 AM CDT POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE. ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD SYSTEM SNOW. THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND REACHING THE TN VALLEY BY SUNDAY EVENING. LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY 18Z SUNDAY. BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7 INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG THE I-80 CORRIDOR. A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S. WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE THEM IN NW IN. ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES. WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE WESTERLIES STAY WELL SOUTH. TRS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS. * POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT SATURDAY. RATZER //DISCUSSION...UPDATED 18Z... SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON. CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS THE SOUTHERN PLAINS. OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON. SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM SYSTEM MOVES INTO THE LOWER OHIO VALLEY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE ON LAKE BREEZE TIMING. * LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING. RATZER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT. SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE AFTERNOON AND NIGHT. MONDAY...MVFR WITH A CHC OF SNOW SHOWERS. TUESDAY...SLT CHC OF SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. MTF && .MARINE... 225 PM CDT A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH TUESDAY. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
225 PM CDT FRI MAR 22 2013 .DISCUSSION... 524 AM CDT POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE. ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD SYSTEM SNOW. THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND REACHING THE TN VALLEY BY SUNDAY EVENING. LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY 18Z SUNDAY. BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7 INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG THE I-80 CORRIDOR. A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S. WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE THEM IN NW IN. ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES. WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE WESTERLIES STAY WELL SOUTH. TRS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS. * POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT SATURDAY. RATZER //DISCUSSION...UPDATED 18Z... SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON. CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS THE SOUTHERN PLAINS. OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON. SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM SYSTEM MOVES INTO THE LOWER OHIO VALLEY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM-LOW CONFIDENCE ON LAKE BREEZE TIMING. * LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING. RATZER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT. SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE AFTERNOON AND NIGHT. MONDAY...MVFR WITH A CHC OF SNOW SHOWERS. TUESDAY...SLT CHC OF SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. MTF && .MARINE... 225 PM CDT A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH TUESDAY. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1251 PM CDT FRI MAR 22 2013 .DISCUSSION... 524 AM CDT POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE. ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD SYSTEM SNOW. THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND REACHING THE TN VALLEY BY SUNDAY EVENING. LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY 18Z SUNDAY. BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7 INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG THE I-80 CORRIDOR. A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S. WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE THEM IN NW IN. ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES. WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE WESTERLIES STAY WELL SOUTH. TRS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS. * POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT SATURDAY. RATZER //DISCUSSION...UPDATED 18Z... SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON. CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS THE SOUTHERN PLAINS. OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON. SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM SYSTEM MOVES INTO THE LOWER OHIO VALLEY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM-LOW CONFIDENCE ON LAKE BREEZE TIMING. * LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING. RATZER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT. SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE AFTERNOON AND NIGHT. MONDAY...MVFR WITH A CHC OF SNOW SHOWERS. TUESDAY...SLT CHC OF SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. MTF && .MARINE... 159 AM CDT PERSISTENT LOW PRESSURE OVER SOUTHERN QUEBEC WILL BEGIN TO FINALLY MOVE EAST LATER TODAY INTO TONIGHT EASING WIND SPEEDS ACROSS THE NORTHERN PART OF THE LAKE. THIS SYSTEM DEPARTURE WILL ALLOW FOR THE HIGH PRESSURE OVER THE MISSISSIPPI RIVER VALLEY TO SHIFT EAST OVER LAKE MI INTO THE DAY SATURDAY. THE MOST PRONOUNCED SYSTEM IMPACTS FOR THE LAKE WILL COME LATER SUNDAY...SUNDAY NIGHT...INTO THE DAY MONDAY AS LOW PRESSURE MOVES FROM THE OZARKS REGION UP THE OHIO RIVER VALLEY. SUCH A PATH WILL TIGHTEN THE PRESSURE GRADIENT ACROSS LAKE MI...ESPECIALLY THE SOUTH. WINDS TO 30 KT LOOK VERY LIKELY OVER THE SOUTHERN HALF INCLUDING NEARSHORE AREAS ON THE SOUTH...WITH GALE FORCE WINDS POSSIBLE DEPENDING ON SYSTEM STRENGTH AND PRECISE PATH. CIPS ANALOG GUIDANCE FOR SIMILAR REGIME MATCHES INDICATE A 50 PERCENT CHANCE OF WIND GUSTS EXCEEDING 30 KT ON NEARBY LAND AREAS FOR THIS TIME...SO OVER WATER THE LIKELIHOOD IS HIGHER. SO BEYOND THIS SYSTEM...GRADUALLY DIMINISHING NORTHERLY FLOW WILL CONTINUE FOR A WHILE WITH PERSISTENT RIDGING BUILDING ONCE AGAIN OVER THE MISSISSIPPI RIVER VALLEY. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
347 PM CDT FRI MAR 22 2013 .DISCUSSION... 20Z WATER VAPOR IMAGERY SHOWS A ELONGATED TROUGH FROM WESTERN CANADA INTO THE NORTHERN ROCKIES WITH ENERGY DIGGING INTO ITS BASE. AT THE SURFACE WEAK RIDGING REMAINS OVER THE NORTHERN AND CENTRAL PLAINS WITH A COOL EASTERLY WIND. FOR TONIGHT...LARGE SCALE FORCING FOR PRECIP LOOKS TO REMAIN TO THE WEST ACROSS THE ROCKIES...SO THINK CHANCES FOR MEASURABLE PRECIP ARE FAIRLY LOW. THE NAM AND RAP ARE SHOWING SOME WEAK ISENTROPIC ACCENT DEVELOPING ON THE 280K SURFACE...SUGGESTING THERE COULD AGAIN BE SOME PATCHY FREEZING DRIZZLE AFTER MIDNIGHT. BECAUSE OF THIS HAVE INSERTED A SLIGHT CHANCE FOR FREEZING DRIZZLE. THINK THAT LOWS TONIGHT SHOULD BE PRETTY SIMILAR TO THE LAST COUPLE NIGHTS GIVEN OVERCAST SKIES AND LITTLE CHANGE TO THE AIRMASS. FOR SATURDAY THROUGH SUNDAY...THE MAIN QUESTION IS WHETHER TO UPGRADE TO A WARNING OR MAINTAIN THE WATCH. MODELS HAVE BEEN CONSISTENT IN AMPLIFYING A SHORTWAVE AND MOVING IT ACROSS THE FORECAST AREA. WITH VERY GOOD LARGE SCALE FORCING FROM THE PV ANOMALY AND Q VECTOR CONVERGENCE...PRECIP IS EXPECTED TO BECOME WIDESPREAD ACROSS WESTERN KS SATURDAY MORNING AND SPREAD EAST INTO EASTERN KS BY THE AFTERNOON. THEREFORE POPS HAVE BEEN INCREASED FOR THE FORECAST AREA SATURDAY AFTERNOON AND SATURDAY NIGHT. THE NAM AND GFS FORECAST SOUNDINGS HAVE TRENDED WARMER WITH THE BOUNDARY LAYER SATURDAY WITH SURFACE TEMPS IN THE UPPER 30S THROUGH THE AFTERNOON ACROSS EAST CENTRAL KS. BECAUSE OF THIS HAVE MOVED THE RAIN/SNOW LINE BACK NORTHWEST EXPECTING AREAS ALONG AND SOUTH OF THE TURNPIKE TO SEE MAINLY RAIN THROUGH THE BULK OF THE DAY SATURDAY. ACROSS NORTH CENTRAL KS...TEMPS LOOK COLD ENOUGH FOR PRECIP TO BE ALL SNOW. AS THE UPPER WAVE PASSES TO THE EAST EARLY SATURDAY EVENING...THE COLD AIR SHOULD FILL IN WITH PRECIP CHANGING TO SNOW DURING THE EVENING. THERE IS SOME UNCERTAINTY IN PRECIP TYPE ACROSS EAST CENTRAL KS FOR SATURDAY EVENING BECAUSE MODELS SHOW MID LEVEL DRY AIR LIFTING INTO THE AREA AND DRYING OUT THE DENDRITIC GROWTH ZONE. WITH NO ICE IN THE CLOUD...THERE COULD BE SIMPLY RAIN FALLING WITH TEMPS IN THE MID 30S. WITH RAIN EXPECTED INITIALLY SATURDAY AND THE POTENTIAL FOR A MIX OF PRECIP SATURDAY EVENING...HAVE KNOCKED DOWN SNOW AMOUNTS ACROSS EAST CENTRAL KS WITH MAYBE AROUND 4 INCHES POSSIBLE BY SUNDAY AFTERNOON. OTHERWISE IT IS NOT CLEAR WHETHER SNOWFALL RATES WILL BE ENHANCED BY MESOSCALE FORCING OR IF IT WILL BE DRIVEN ALL BY SYNOPTIC FORCING. THERE DOES APPEAR TO BE SOME UPRIGHT INSTABILITY ON SATURDAY WHICH COULD INCREASE SNOWFALL RATES. AND THE NAM HINTS AT A WEAK TROWAL SATURDAY NIGHT. HOWEVER IT ONLY REALLY SHOWS UP AROUND 600 MB AND IS NOT VERY DEEP. CONSIDERING THE SURFACE LOW COULD END UP OVER TN OR MS BY 12Z SUNDAY...AM NOT SURE THE WARM CONVEYOR BELT WOULD WRAP ALL THE WAY BACK INTO EASTERN KS. PERHAPS THE ENHANCED QPF FROM THE NAM IS A FUNCTION OF THE UPPER LEVEL DEFORMATION FROM THE WAVE PROPAGATING EAST. SO FOR FAR NORTHEAST AND NORTH CENTRAL KS...THE FORECAST IS STILL CALLING FOR AROUND 5 TO 7 INCHES. HAVE DECIDED TO UPGRADE AREAS WEST OF MHK TO A WARNING SINCE THEY SHOULD BEGIN TO BE IMPACTED BY THE STORM BY NOON TOMORROW. SINCE PRECIP MAY END UP BEING MORE RAIN IN EAST CENTRAL KS AND THE SNOW COULD HOLD OFF UNTIL SATURDAY EVENING...WILL KEEP THE WATCH GOING FOR AREAS EAST OF MHK AND LET LATER SHIFTS HAVE A LOOK AT THE NEWER GUIDANCE. WITH MODELS ADVECTING A LITTLE MORE WARM AIR INTO EASTERN KS...HAVE BUMPED HIGHS UP TO AROUND 40 IN THE EAST WITH HIGHS NEAR THE FREEZING MARK ACROSS NORTH CENTRAL KS. LOWS SUNDAY MORNING SHOULD FALL INTO THE 20S AS NORTHWEST WINDS INCREASE AND BRING COLDER AIR SOUTH. CLOUD COVER AND BREEZY NORTHWEST WINDS SHOULD KEEP TEMPS FROM WARMING MUCH ON SUNDAY...SO HIGHS ARE FORECAST TO BE IN THE LOWER TO MID 30S. WOLTERS SUNDAY NIGHT THROUGH FRIDAY... SECONDARY UPPER TROF SWINGS THROUGH LATE SUNDAY NIGHT AND MONDAY WITH LIMITED FORCING AND ONLY SHALLOW MOISTURE SO WILL KEEP DRY FORECAST GOING. NORTHWEST WINDS PERSIST WITH TEMPS OVER THE FRESH SNOW NOT WARMING MUCH. SURFACE RIDGE AXIS TAKES RESIDENCE MONDAY NIGHT INTO TUESDAY AS ZONAL FLOW BEGINS TO TAKE HOLD OF THE SOUTHWESTERN THIRD OF THE CONUS. SOUTH WINDS KICK IN FOR AT LEAST THE BULK OF THE AREA WEDNESDAY FOR A MORE SIGNIFICANT WARM-UP...THOUGH MODELS DIVERGE SOMEWHAT WITH SHORTWAVES COMING SOUTHEAST ACROSS THE NORTHERN PLAINS AND GREAT LAKES...WHICH COULD LEAVE A MODIFIED BOUNDARY OVER THE CENTRAL PLAINS. INCREASING LOW LEVEL MOISTURE VIA THE SOUTH WINDS COMBINED WITH THE CONVERGENCE COULD BE ENOUGH FOR SOME CHANCE FOR MAINLY RAIN FOR THE LATTER PERIODS. THOUGH CONFIDENCE IS NOT HIGH GIVEN EASTERLY LOW LEVEL FLOW POTENTIAL...WILL BRING TEMPS UP TO NEAR LATE MARCH NORMALS. 65 && .AVIATION... IFR CONDITIONS SHOULD CONTINUE THROUGH THE EARLY AFTERNOON HOURS. THE STRATUS DECK IS BEGINNING TO BREAK UP ACROSS CENTRAL KANSAS THEREFORE MVFR CONDITIONS ARE EXPECTED AROUND 20Z. THERE MAY BE A BRIEF PERIOD OF VFR CONDITIONS THIS EVENING BEFORE THE MVFR CONDITIONS RETURN AGAIN AROUND 07Z. DRIZZLE MAY ALSO DEVELOP OVERNIGHT AS SOUNDINGS SHOW WEAK LIFT IN A SATURATED LOW LEVEL LAYER. THE MORE IMPRESSIVE LIFT AND COLUMN SATURATION ASSOCIATED WITH THE MAIN STORM SYSTEM WILL BEGIN TO EFFECT THE AREA AROUND 15Z. ALTHOUGH CONFIDENCE IN THE START TIME OF PRECIP IS LOW. THEREFORE LATER SHIFTS WILL MONITOR THE SITUATION AND CONTINUE UPDATES. SANDERS && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR KSZ011-012-023-024-026-037>040-054>056-058-059. WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM CDT SUNDAY FOR KSZ008>010-020>022-034>036. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
140 PM CDT FRI MAR 22 2013 ...UPDATED WITH A LATE AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 252 AM CDT FRI MAR 22 2013 THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID LEVELS EXHIBITS COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC LIFT. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 252 AM CDT FRI MAR 22 2013 NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND 18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND. WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND INTO TONIGHT. WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 429 AM CDT FRI MAR 22 2013 WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL GET THE BRUNT OF THE STORM. 400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE 32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY 83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO 25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR. THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY 283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL. GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700 WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST. THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST OF THE DAY. UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS 60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE END THE MONTH OF MARCH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 135 PM CDT FRI MAR 22 2013 FOR THE REST OF TODAY, SKIES WILL BE MOSTLY CLEAR AS A SMALL WEDGE OF HIGH PRESSURE CONTROLS THE AREA. A LARGE UPPER LEVEL SYSTEM IS MOVING TOWARD WESTERN KANSAS FROM THE WEST. WINDS WILL BASICALLY BE LIGHT AND VARIABLE THROUGH 23Z, THEN BECOME EAST AT AROUND 15 KNOTS. OVERNIGHT, LOW LEVEL MOISTURE WILL RIDE UP FROM THE SOUTH AND SOUTHEAST, AND DEVELOP INTO IFR CIGS AFTER 09Z TONIGHT. THE BIGGER SHOW OF DRIZZLE AND THEN SNOW COMES LATER ON SATURDAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 34 35 23 30 / 10 90 90 10 GCK 32 33 21 30 / 10 90 90 0 EHA 36 37 21 34 / 10 90 80 10 LBL 37 38 23 34 / 10 90 80 10 HYS 29 31 23 30 / 90 90 90 30 P28 35 38 28 35 / 10 90 80 40 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM 1 AM CDT /MIDNIGHT MDT/ SATURDAY THROUGH SUNDAY MORNING FOR KSZ030-031-043>046-061>066. WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY FOR KSZ074>081-084>090. && $$ SYNOPSIS...RUSSELL SHORT TERM...RUSSELL LONG TERM...UMSCHEID AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
144 PM EDT FRI MAR 22 2013 .UPDATE... ISSUED AT 1040 AM EDT FRI MAR 22 2013 SOME SLIGHTLY DEEPER MOISTURE HAS MOVED INTO THE AREA...JUST ENOUGH TO ALLOW SOME SNOW TO MIX IN WITH THE FREEZING DRIZZLE DUE TO THE TOP OF THE CLOUD BEING AROUND -12C. HOWEVER...THIS IS EXPECTED TO ONLY LAST A FEW HOURS PER THE RAP SOUNDINGS. OTHERWISE...HAVE OPTED TO KEEP FREEZING DRIZZLE AROUND FOR MUCH OF THE DAY CLOSER TO LAKE SUPERIOR DUE TO THE PERSISTENT UPSLOPE FLOW THROUGH THE DAY AND SHALLOW MOISTURE. ANY SURFACES THAT ARE UNTREATED MAY BE SLIPPERY AT TIMES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 505 AM EDT FRI MAR 22 2013 UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM... SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE. BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON 00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR FZDZ. WILL PULL THE MENTION OF FZDZ. STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 505 AM EDT FRI MAR 22 2013 A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S. SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING. SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT. HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF INCH. TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 144 PM EDT FRI MAR 22 2013 EXPECT -SHSN AND LIGHT DRIZZLE/BR THIS AFTERNOON AT SAW AND CMX TO DIMINISH AS LOW LEVEL MIXING OCCURS. MOISTURE THEN INCREASES TONIGHT WITH CONTINUE NLY LOW LEVEL WINDS...SO -FZDZ WILL REOCCUR AS IT DID THIS MORNING AND CONTINUE INTO SAT MORNING. ONCE LOW LEVEL MIXING INCREASING LATE SAT MORNING...SHOULD SEE -FZDZ DIMINISH. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 505 AM EDT FRI MAR 22 2013 HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS THAN 25 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...MRD SHORT TERM...JLA LONG TERM...JLB AVIATION...TITUS MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1229 PM CDT FRI MAR 22 2013 .AVIATION...18Z TAF ISSUANCE... AREAS OF BKN MVFR CIGS ARE LINGERING ACROSS THE REGION EARLY THIS AFTERNOON WITH A BAND OF MID LVL CLOUDS EXTENDING FROM FGN TO TWM TO PBH. MVFR CIGS HAVE MOVED IN OVER DLH AND COULD REMAIN THROUGH THE AFTERNOON WITH A WEAK NE WIND OFF THE LAKE SUPPLEMENTING THE AVAILABLE MOISTURE. QUITE A BIT OF UNCERTAINTY REGARDING CIG FORECAST TODAY. A BETTER CHANCE OF LOW CLOUDS TONIGHT. WINDS WILL REMAIN LIGHT THROUGH THE PERIOD. && .PREV DISCUSSION... /ISSUED 924 AM CDT FRI MAR 22 2013/ UPDATE...PROGRESSIONS OF CLOUDS THROUGH THE ARROWHEAD AND ALONG THE INTERNATIONAL BORDER HAS SLOWED QUITE A BIT. THERE IS SOME EROSION OCCURRING ALONG THE LEADING EDGE. HAVE UPDATED THE SKY GRIDS TO ACCOUNT FOR THIS TREND. RAISED MAX TEMPS A BIT AS TEMPS ARE RECOVERING QUICKLY WHERE THERE IS FULL SUN...AND ESPECIALLY IN THE FORESTED AREAS IN NW WI. BROUGHT DEWPOINTS UP AS WELL FOR THE SAME REASON. PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAR 22 2013/ AVIATION...12Z TAF ISSUANCE. A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER 02Z. PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/ SHORT TERM...THROUGH SATURDAY. THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION TONIGHT INTO SATURDAY. THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING. THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA. THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F. TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT. A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN. HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS. LONG TERM...SAT NIGHT THROUGH FRIDAY. THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE INTRODUCED BROAD BRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT WEEK. BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST. LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH MID-WEEK. && .POINT TEMPS/POPS... DLH 14 34 17 31 / 0 10 10 10 INL 8 33 15 32 / 0 10 10 10 BRD 11 35 18 32 / 0 10 10 10 HYR 8 35 16 34 / 0 10 10 10 ASX 12 34 17 32 / 0 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ AVIATION...TENTINGER
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
103 PM CDT FRI MAR 22 2013 .DISCUSSION... SEE AVIATION SECTION. && .AVIATION... THE LOW CLOUD FIELD ACROSS THE BIG COUNTRY WILL CONTINUE TO SLOWLY ERODE THIS AFTERNOON. EXPECT SCATTERED COVERAGE AT KABI 21-23Z. COLD FRONTAL BOUNDARY WILL WEAKEN THROUGH THE REMAINDER OF THIS AFTERNOON AS IT DRIFTS SOUTH ACROSS THE INTERSTATE 10 CORRIDOR. THE FRONTAL BOUNDARY SHOULD STALL NEAR OR JUST SOUTH OF THE SOUTHERN BORDER OF OUR FORECAST/WARNING AREA THIS EVENING. THE FRONT WILL RETURN NORTH AS A WARM FRONT TONIGHT...WITH WINDS BECOMING SOUTHEAST OVERNIGHT. EXPECT LOW CLOUDS TO DEVELOP AND EXPAND WEST ACROSS PARTS OF OUR AREA AFTER 06Z...AND CEILINGS TO BE IN THE 1K-2K FT RANGE. WINDS WILL VEER TO SOUTH EARLY SATURDAY MORNING. PACIFIC FRONT/DRYLINE PASSAGE EXPECTED IN THE 15Z-18Z TIME FRAME...FOLLOWED BY INCREASING AND GUSTY WEST WINDS. THIS WILL ALSO QUICKLY SCOUR OUT THE LOW-LEVEL MOISTURE AND CLOUD COVER. && .PREV DISCUSSION... /ISSUED 1124 AM CDT FRI MAR 22 2013/ UPDATE... FORECAST HAS BEEN UPDATED MAINLY FOR TEMPERATURES TODAY... SEE DISCUSSION. DISCUSSION... SURFACE COLD FRONT HAS PROGRESSED INTO OUR SOUTHERN COUNTIES LATE THIS MORNING. AT 11 AM THE FRONT EXTENDED FROM JUST SOUTH OF MASON TO JUST NORTH OF OZONA. THE LATEST RUC13 AND NAM12 MODELS HAVE THE FRONT MOVING AT A MUCH SLOWER PACE THIS AFTERNOON ACROSS OUR SOUTHERNMOST COUNTIES. THIS FRONT IS EXPECTED TO STALL NEAR OR JUST SOUTH OF OUR FORECAST/WARNING AREA THIS EVENING. LOW CLOUD COVER HAS DEVELOPED AND PERSISTED ACROSS THE BIG COUNTRY...AND WAS MORE PATCHY ACROSS THE SOUTHERN HEARTLAND AND SOUTHERN CONCHO VALLEY. THE COMBINATION OF COLD AIR ADVECTION AND CLOUD COVER HAS RESULTED IN LITTLE TEMPERATURE RECOVERY ACROSS THE BIG COUNTRY. THE MODEL LOW-LEVEL MOISTURE FIELDS INDICATE THAT THE SOUTHERN END OF THE LOW CLOUD FIELD ACROSS THE BIG COUNTRY WILL SLOWLY ERODE THIS AFTERNOON... BUT SHOULD REMAIN PERSISTENT ACROSS THE NORTHERNMOST COUNTIES. WITH THE COLD AIR ADVECTION BEHIND THE FRONT A LITTLE STRONGER THAN PREVIOUSLY ANTICIPATED...HAVE LOWERED TEMPERATURES THIS AFTERNOON ACROSS OUR NORTHERN AND CENTRAL COUNTIES. TEMPERATURES STILL LOOK ON TARGET ACROSS THE FAR SOUTHERN PART OF OUR AREA. SHOULD END UP WITH ABOUT A 30 DEGREE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS WEST CENTRAL TEXAS WITH THE HIGHS THIS AFTERNOON. FORECAST PRODUCTS HAVE BEEN UPDATED. PREV DISCUSSION... /ISSUED 612 AM CDT FRI MAR 22 2013/ DISCUSSION... SEE AVIATION DISCUSSION BELOW. AVIATION... VFR OR MVFR FLYING CONDITIONS ARE EXPECTED ACROSS WEST CENTRAL TEXAS THE NEXT 24 HOURS. A COLD FRONT WILL MOVE FROM NORTH TO SOUTH THROUGH THE FORECAST AREA TODAY. ALTHOUGH NO RAIN IS EXPECTED FROM THE FRONT SOME LOW CLOUDS ARE EXPECTED TO MOVE THROUGH THE AREA WITH IT. CLOUD CEILINGS COULD BRIEFLY LOWER AIRPORT WEATHER CONDITIONS TO MVFR WITH BROKEN CLOUD COVER POSSIBLY BECOMING OVERCAST BELOW THREE THOUSAND FEET. ON SATURDAY A PACIFIC FRONT WILL BREEZE THROUGH THE FORECAST AREA FROM WEST TO EAST BRINGING BRISK WINDS OF 20 TO 25 MPH WITH HIGHER GUST ACROSS THE AREA SATURDAY AFTERNOON. RELATIVE HUMIDITY WILL PLUMMET INTO THE TEENS AND SINGLE DIGITS AND WILL CLEAR AWAY MOST LOW CLOUDS ACROSS THE FORECAST AREA BY AFTERNOON. A THIRD COLD WILL MOVE FROM NORTH TO SOUTH ACROSS THE FORECAST AREA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING. BRISK 20 TO 25 MPH NORTH WINDS WILL ACCOMPANY THIS FRONT AND BRING SIGNIFICANTLY COOLER MORNING TEMPERATURES ACROSS THE AREA WITH LOWS NEAR OR SLIGHTLY BELOW FREEZING ON MONDAY AND ON TUESDAY MORNING. PREV DISCUSSION... /ISSUED 415 AM CDT FRI MAR 22 2013/ SHORT TERM... LIGHT SOUTH SOUTHWEST WINDS OF 10 TO 15KT WILL PREVAIL THROUGH DAWN HOURS ACROSS WEST CENTRAL TEXAS. A WEAK SURFACE LOW PRESSURE AREA ABOUT 50 MILES NORTHEAST OF THROCKMORTON COUNTY WILL MOVE EAST BY EARLY MORNING HOURS AND A COLD FRONT WILL MOVE THROUGH THE AREA ON FRIDAY. WINDS FROM THE NORTH AT 12 TO 18KT WITH SOME HIGHER GUSTS WILL FOLLOW IMMEDIATELY BEHIND THE COLD FRONT THAT WILL BE ACCOMPANIED BY SOME LOW CLOUDS. BY EARLY FRIDAY EVENING WINDS FROM THE NORTH WILL WEAKEN TO 10 TO 15KT AND ANY LOW CLOUDS ASSOCIATED WITH THE FRONT WILL MOVE EAST OUT OF THE FORECAST AREA. LIGHT 5 TO 10 KT EAST AND NORTHEAST WINDS WILL DOMINATE OVERNIGHT FRIDAY INTO EARLY SATURDAY AND SOME LOW CLOUDS AND MOISTER AIR WILL RETURN FROM THE EAST TO EASTERN AND CENTRAL COUNTIES. A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS FROM NOON TO 7PM SATURDAY...IN ASSOCIATION WITH A PACIFIC COLD FRONT THAT WILL BLAST EAST THROUGH THE AREA BEGINNING LATE SATURDAY MORNING. AFTERNOON AND EARLY EVENING WINDS ON SATURDAY WILL BLOW FROM THE WEST AT 18 TO 22KT WITH HIGHER GUSTS AND WILL BE ACCOMPANIED BY VERY DRY AIR...RELATIVE HUMIDITY WILL DROP INTO THE LOW TEENS AND SINGLE DIGITS. NEAR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED AND RED FLAG WARNINGS MAY BE NECESSARY FOR SOME COUNTIES SATURDAY AFTERNOON AND EARLY SATURDAY EVENING...ESPECIALLY ACROSS WEST AND SOUTHWEST COUNTIES. LONG TERM... A STRONG COLD FRONT WILL PUSH THROUGH WEST CENTRAL TEXAS SATURDAY EVENING. COULD SEE NORTH WINDS SUSTAINED NEAR 30 MPH...WITH GUSTS IN THE LOWER 40S FOR SEVERAL HOURS BEHIND THE FRONT. THE AIR WILL BE QUITE DRY...AND FIRE WEATHER CONDITIONS WILL CONTINUE TO BE ELEVATED. FIRE DEPARTMENTS WORKING ANY WILDFIRES EARLIER ON SATURDAY SHOULD BE ALERT TO THE SUDDEN CHANGE IN WIND DIRECTION. FREEZE POSSIBLE MONDAY AND TUESDAY MORNING AS THE 1030 MB SURFACE HIGH PRESSURE...WITH ORIGINS IN WESTERN CANADA...BUILDS DIRECTLY OVER THE REGION. A BIT TOO EARLY TO KNOW HOW COLD IT WILL BE. MODELS ARE SUGGESTING A LIGHT FREEZE IN THE 30 TO 32 RANGE MONDAY MORNING...WITH PERHAPS A DEGREE OR TWO LOWER TUESDAY MORNING (DUE TO WEAKER WINDS). IN ANY CASE...WITH THE GROWING SEASON STARTING...LOOK FOR POTENTIAL FREEZE WARNINGS ISSUED LATER THIS WEEKEND...IF CONDITIONS CONTINUE TO WARRANT. LOW LEVEL MOISTURE WILL FINALLY RETURN MIDWEEK. MODELS DO NOT INDICATED MUCH LIFT AND MID LEVELS ARE DRY...SO WILL NOT BE ADDING ANY RAINFALL CHANCES. 04 FIRE WEATHER... ELEVATED TO FIRE WEATHER CONDITIONS WILL OCCUR FRIDAY FROM THE COMBINATION OF BRISK NORTH WINDS AND DRY AIR BEHIND A COLD FRONT. NEAR CRITICAL FIRE WEATHER IS EXPECTED MIDDAY TO EVENING HOURS ON SATURDAY...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS FROM NOON TO 7PM SATURDAY. RED FLAG WARNINGS MAY BE NECESSARY...WEST AND SOUTHWEST COUNTIES WILL BE MOST THREATENED. LYONS && .PRELIMINARY POINT TEMPS/POPS... ABILENE 55 49 79 33 55 / 5 10 10 5 5 SAN ANGELO 72 53 86 38 59 / 0 10 10 5 5 JUNCTION 85 55 87 40 63 / 0 10 10 5 5 && .SJT WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING FOR THE FOLLOWING ZONES: CALLAHAN...COKE...COLEMAN... CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE... MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SCHLEICHER... STERLING...SUTTON...TAYLOR...TOM GREEN. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1124 AM CDT FRI MAR 22 2013 .UPDATE... FORECAST HAS BEEN UPDATED MAINLY FOR TEMPERATURES TODAY... SEE DISCUSSION. && .DISCUSSION... SURFACE COLD FRONT HAS PROGRESSED INTO OUR SOUTHERN COUNTIES LATE THIS MORNING. AT 11 AM THE FRONT EXTENDED FROM JUST SOUTH OF MASON TO JUST NORTH OF OZONA. THE LATEST RUC13 AND NAM12 MODELS HAVE THE FRONT MOVING AT A MUCH SLOWER PACE THIS AFTERNOON ACROSS OUR SOUTHERNMOST COUNTIES. THIS FRONT IS EXPECTED TO STALL NEAR OR JUST SOUTH OF OUR FORECAST/WARNING AREA THIS EVENING. LOW CLOUD COVER HAS DEVELOPED AND PERSISTED ACROSS THE BIG COUNTRY...AND WAS MORE PATCHY ACROSS THE SOUTHERN HEARTLAND AND SOUTHERN CONCHO VALLEY. THE COMBINATION OF COLD AIR ADVECTION AND CLOUD COVER HAS RESULTED IN LITTLE TEMPERATURE RECOVERY ACROSS THE BIG COUNTRY. THE MODEL LOW-LEVEL MOISTURE FIELDS INDICATE THAT THE SOUTHERN END OF THE LOW CLOUD FIELD ACROSS THE BIG COUNTRY WILL SLOWLY ERODE THIS AFTERNOON... BUT SHOULD REMAIN PERSISTENT ACROSS THE NORTHERNMOST COUNTIES. WITH THE COLD AIR ADVECTION BEHIND THE FRONT A LITTLE STRONGER THAN PREVIOUSLY ANTICIPATED...HAVE LOWERED TEMPERATURES THIS AFTERNOON ACROSS OUR NORTHERN AND CENTRAL COUNTIES. TEMPERATURES STILL LOOK ON TARGET ACROSS THE FAR SOUTHERN PART OF OUR AREA. SHOULD END UP WITH ABOUT A 30 DEGREE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS WEST CENTRAL TEXAS WITH THE HIGHS THIS AFTERNOON. FORECAST PRODUCTS HAVE BEEN UPDATED. && .PREV DISCUSSION... /ISSUED 612 AM CDT FRI MAR 22 2013/ DISCUSSION... SEE AVIATION DISCUSSION BELOW. AVIATION... VFR OR MVFR FLYING CONDITIONS ARE EXPECTED ACROSS WEST CENTRAL TEXAS THE NEXT 24 HOURS. A COLD FRONT WILL MOVE FROM NORTH TO SOUTH THROUGH THE FORECAST AREA TODAY. ALTHOUGH NO RAIN IS EXPECTED FROM THE FRONT SOME LOW CLOUDS ARE EXPECTED TO MOVE THROUGH THE AREA WITH IT. CLOUD CEILINGS COULD BRIEFLY LOWER AIRPORT WEATHER CONDITIONS TO MVFR WITH BROKEN CLOUD COVER POSSIBLY BECOMING OVERCAST BELOW THREE THOUSAND FEET. ON SATURDAY A PACIFIC FRONT WILL BREEZE THROUGH THE FORECAST AREA FROM WEST TO EAST BRINGING BRISK WINDS OF 20 TO 25 MPH WITH HIGHER GUST ACROSS THE AREA SATURDAY AFTERNOON. RELATIVE HUMIDITY WILL PLUMMET INTO THE TEENS AND SINGLE DIGITS AND WILL CLEAR AWAY MOST LOW CLOUDS ACROSS THE FORECAST AREA BY AFTERNOON. A THIRD COLD WILL MOVE FROM NORTH TO SOUTH ACROSS THE FORECAST AREA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING. BRISK 20 TO 25 MPH NORTH WINDS WILL ACCOMPANY THIS FRONT AND BRING SIGNIFICANTLY COOLER MORNING TEMPERATURES ACROSS THE AREA WITH LOWS NEAR OR SLIGHTLY BELOW FREEZING ON MONDAY AND ON TUESDAY MORNING. PREV DISCUSSION... /ISSUED 415 AM CDT FRI MAR 22 2013/ SHORT TERM... LIGHT SOUTH SOUTHWEST WINDS OF 10 TO 15KT WILL PREVAIL THROUGH DAWN HOURS ACROSS WEST CENTRAL TEXAS. A WEAK SURFACE LOW PRESSURE AREA ABOUT 50 MILES NORTHEAST OF THROCKMORTON COUNTY WILL MOVE EAST BY EARLY MORNING HOURS AND A COLD FRONT WILL MOVE THROUGH THE AREA ON FRIDAY. WINDS FROM THE NORTH AT 12 TO 18KT WITH SOME HIGHER GUSTS WILL FOLLOW IMMEDIATELY BEHIND THE COLD FRONT THAT WILL BE ACCOMPANIED BY SOME LOW CLOUDS. BY EARLY FRIDAY EVENING WINDS FROM THE NORTH WILL WEAKEN TO 10 TO 15KT AND ANY LOW CLOUDS ASSOCIATED WITH THE FRONT WILL MOVE EAST OUT OF THE FORECAST AREA. LIGHT 5 TO 10 KT EAST AND NORTHEAST WINDS WILL DOMINATE OVERNIGHT FRIDAY INTO EARLY SATURDAY AND SOME LOW CLOUDS AND MOISTER AIR WILL RETURN FROM THE EAST TO EASTERN AND CENTRAL COUNTIES. A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS FROM NOON TO 7PM SATURDAY...IN ASSOCIATION WITH A PACIFIC COLD FRONT THAT WILL BLAST EAST THROUGH THE AREA BEGINNING LATE SATURDAY MORNING. AFTERNOON AND EARLY EVENING WINDS ON SATURDAY WILL BLOW FROM THE WEST AT 18 TO 22KT WITH HIGHER GUSTS AND WILL BE ACCOMPANIED BY VERY DRY AIR...RELATIVE HUMIDITY WILL DROP INTO THE LOW TEENS AND SINGLE DIGITS. NEAR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED AND RED FLAG WARNINGS MAY BE NECESSARY FOR SOME COUNTIES SATURDAY AFTERNOON AND EARLY SATURDAY EVENING...ESPECIALLY ACROSS WEST AND SOUTHWEST COUNTIES. LONG TERM... A STRONG COLD FRONT WILL PUSH THROUGH WEST CENTRAL TEXAS SATURDAY EVENING. COULD SEE NORTH WINDS SUSTAINED NEAR 30 MPH...WITH GUSTS IN THE LOWER 40S FOR SEVERAL HOURS BEHIND THE FRONT. THE AIR WILL BE QUITE DRY...AND FIRE WEATHER CONDITIONS WILL CONTINUE TO BE ELEVATED. FIRE DEPARTMENTS WORKING ANY WILDFIRES EARLIER ON SATURDAY SHOULD BE ALERT TO THE SUDDEN CHANGE IN WIND DIRECTION. FREEZE POSSIBLE MONDAY AND TUESDAY MORNING AS THE 1030 MB SURFACE HIGH PRESSURE...WITH ORIGINS IN WESTERN CANADA...BUILDS DIRECTLY OVER THE REGION. A BIT TOO EARLY TO KNOW HOW COLD IT WILL BE. MODELS ARE SUGGESTING A LIGHT FREEZE IN THE 30 TO 32 RANGE MONDAY MORNING...WITH PERHAPS A DEGREE OR TWO LOWER TUESDAY MORNING (DUE TO WEAKER WINDS). IN ANY CASE...WITH THE GROWING SEASON STARTING...LOOK FOR POTENTIAL FREEZE WARNINGS ISSUED LATER THIS WEEKEND...IF CONDITIONS CONTINUE TO WARRANT. LOW LEVEL MOISTURE WILL FINALLY RETURN MIDWEEK. MODELS DO NOT INDICATED MUCH LIFT AND MID LEVELS ARE DRY...SO WILL NOT BE ADDING ANY RAINFALL CHANCES. 04 FIRE WEATHER... ELEVATED TO FIRE WEATHER CONDITIONS WILL OCCUR FRIDAY FROM THE COMBINATION OF BRISK NORTH WINDS AND DRY AIR BEHIND A COLD FRONT. NEAR CRITICAL FIRE WEATHER IS EXPECTED MIDDAY TO EVENING HOURS ON SATURDAY...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS FROM NOON TO 7PM SATURDAY. RED FLAG WARNINGS MAY BE NECESSARY...WEST AND SOUTHWEST COUNTIES WILL BE MOST THREATENED. LYONS && .PRELIMINARY POINT TEMPS/POPS... ABILENE 55 49 79 34 55 / 5 10 10 5 5 SAN ANGELO 72 53 86 38 59 / 0 10 10 5 5 JUNCTION 85 55 87 43 63 / 0 10 10 5 5 && .SJT WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING FOR THE FOLLOWING ZONES: CALLAHAN...COKE...COLEMAN... CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE... MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SCHLEICHER... STERLING...SUTTON...TAYLOR...TOM GREEN. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
559 PM CDT FRI MAR 22 2013 .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT 310 PM CDT FRI MAR 22 2013 THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES ACROSS PARTS OF THE AREA. AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPULSES IN THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL. JUST A UPWARD NUDGE COMPARED TO YESTERDAY. QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS. HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST. HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE. THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT. AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL ACCUMULATIONS. REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND 6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2 INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT. IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY / SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90. HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS. .LONG TERM...MONDAY THROUGH FRIDAY 310 PM CDT FRI MAR 22 2013 IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO -1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT WEEKEND POSSIBLY. && .AVIATION...TONIGHT AND SATURDAY 559 PM CDT FRI MAR 22 2013 A RIDGE OF HIGH PRESSURE OVER THE TAF SITES IS FORECAST TO BREAK DOWN OVER THE NEXT 24 HOURS AS LOW PRESSURE DEVELOPS OVER THE CENTRAL PLAINS. AS THIS OCCURS...NORTHEAST FLOW WILL VERY SLOWLY DEVELOP IN THE LOWER LEVELS OF THE ATMOSPHERE. LOOKING TO THE NORTHEAST...THERE IS A MVFR-VFR STRATUS ACROSS FAR NORTHEAST WISCONSIN INTO UPPER MICHIGAN. WITH WINDS BASICALLY LIGHT AND VARIABLE TONIGHT...ANTICIPATING THAT THIS STRATUS DECK WILL NOT MOVE MUCH. A BETTER SHOT OF THE STRATUS MOVING TOWARDS THE TAF SITES COMES TOMORROW AS THE NORTHEAST WIND PICKS UP. EVEN THEN...DAYTIME HEATING SHOULD BE ENOUGH TO MIX THE STRATUS DECK TO A VFR CEILING AT BOTH TAF SITES. OTHERWISE...SOME ALTOSTRATUS WILL GRADUALLY SPREAD ACROSS THE TAF SITES DURING THE NEXT 24 HOURS...WELL AHEAD OF THE DEVELOPING STORM SYSTEM. THIS ALTOSTRATUS IS ALREADY APPROACHING KRST THIS EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... 310 PM CDT FRI MAR 22 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...ZT LONG TERM...ZT AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
310 PM CDT FRI MAR 22 2013 .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT 310 PM CDT FRI MAR 22 2013 THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES ACROSS PARTS OF THE AREA. AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPLUSES IN THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL. JUST A UPWARD NUDGE COMPARED TO YESTERDAY. QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS. HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST. HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE. THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT. AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL ACCUMULATIONS. REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND 6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2 INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT. IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY / SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90. HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS. .LONG TERM...MONDAY THROUGH FRIDAY 310 PM CDT FRI MAR 22 2013 IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO -1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT WEEKEND POSSIBLY. && .AVIATION...THROUGH 18Z SATURDAY 1253 PM CDT FRI MAR 22 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH PRESSURE WILL REMAIN OVER THE UPPER MISSISSIPPI RIVER VALLEY THROUGH SATURDAY AFTERNOON PROVIDING QUIET WEATHER. CIRRUS IS EXPECTED TO SPREAD FROM WEST TO EAST ACROSS THE AREA LATE THIS EVENING THROUGH THE OVERNIGHT HOURS AS A TROUGH MOVES INTO THE CENTRAL PLAINS. && .ARX WATCHES/WARNINGS/ADVISORIES... 310 PM CDT FRI MAR 22 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...ZT LONG TERM...ZT AVIATION...WETENKAMP