Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 240530 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1230 AM EST TUE FEB 24 2015 .SYNOPSIS... ARCTIC HIGH PRESSURE IN THE OHIO VALLEY WILL BUILD OVER OUR AREA OVERNIGHT AND THEN SHIFT OFFSHORE TUESDAY. LOW PRESSURE FORMS OFF THE MID ATLANTIC COAST TUESDAY NIGHT AND THEN SCOOTS NORTHEASTWARD. A STRONG COLD FRONT WILL PASS ACROSS OUR AREA WEDNESDAY, THEN A MORE POTENT LOW PRESSURE SYSTEM ALONG THE GULF COAST WEDNESDAY EVENING RACES OUT TO SEA WELL TO OUR EAST ON THURSDAY. STRONG ARCTIC HIGH PRESSURE CENTERED IN MONTANA WILL ARRIVE ALONG THE MID ATLANTIC COAST NEXT WEEKEND, THEN A COLD FRONT APPROACHES FROM THE WEST NEXT MONDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... ARCTIC HIGH PRESSURE WILL BUILD OVER OUR AREA DURING THE OVERNIGHT. AS THIS OCCURS THE PRESSURE GRADIENT WILL CONTINUE TO RELAX AND THEREFORE THE WINDS WILL DIMINISH. THE DOWNWARD TREND IN THE WINDS HAS ALREADY OCCURRED. THIS ALONG WITH A VERY DRY AIRMASS, A CLEAR SKY AND SNOW COVER WILL RESULT IN RECORD COLD FOR SEVERAL AREAS EARLY TUESDAY. FOR THE LOCATIONS WHERE THE WIND DROPS OFF FASTER, TEMPERATURES WILL PLUMMET. THERE WILL BE ENOUGH WIND FOR AWHILE IN THE POCONOS COMBINED WITH THE BITTERLY COLD AIR TO PRODUCE WIND CHILL VALUES AROUND 15 DEGREES BELOW ZERO. THEREFORE THE WIND CHILL ADVISORY REMAINS IN EFFECT FOR THE POCONOS. ELSEWHERE, IT WILL ALSO BE BITTERLY COLD BUT BECAUSE OF LESSENING WINDS THE WIND CHILLS ARE EXPECTED TO NOT REACH ADVISORY CRITERIA. THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, TAKING INTO ACCOUNT SOME OF THE FASTER TEMPERATURE DROP NOW OCCURRING. SINCE THE WINDS ARE DIMINISHING PLUS WITH A RATHER DRY AIRMASS AND SNOW COVER, DID ADJUST THE LOW TEMPERATURES DOWN SOME ESPECIALLY ACROSS THE WESTERN ZONES. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... TUESDAY STARTS OFF COLD WITH WITH LIGHT WINDS. AS WINDS INCREASE, THE WIND CHILLS WILL REMAIN AT OR BELOW ZERO, WITH THE POCONOS REMAINING BELOW ADVISORY LEVELS, SO THE WIND CHILL ADVISORY CONTINUES INTO TUESDAY MORNING. DAYTIME HIGHS ARE NOT EXPECTED TO CLIMB OUT OF THE TEENS FOR THE NORTHERN HALF OF THE AREA, AND REMAIN IN THE 20S FOR THE SOUTHERN HALF. AS HIGH PRESSURE SHIFTS EASTWARD, WINDS WILL EVENTUALLY BECOME MORE SOUTHEASTERLY- SOUTHWESTERLY. CLOUDS WILL INCREASE DURING THE DAY, BUT WE DO NOT ANTICIPATE ANY PRECIPITATION DURING THE DAY. ANY PRECIPITATION IS EXPECTED TO REMAIN TO OUR WEST AS A SHORT WAVE MOVES INTO WESTERN/CENTRAL PENNSYLVANIA. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... **TOP 6 COLDEST FEBRUARY ON RECORD APPEARS ASSURED WITH NO SIGNIFICANT BRIEF WARMUP TIL SUNDAY OR MONDAY** 500MB: A SHARP NORTHERN STREAM TROUGH FROM JAMES BAY TO THE GREAT LAKES TUESDAY NIGHT WILL MOVE TO NEW ENGLAND BY LATE WEDNESDAY WHILE A WEAKER SOUTHERN STREAM SHORT WAVE IN THE GULF STATES DEPARTS NORTHEAST FROM THE CAROLINA COASTS WEDNESDAY NIGHT. THEREAFTER CONSIDERABLE UNCERTAINTY EXISTS IN DETAILS BUT OVERALL...A BROAD TROUGH COVERS CANADA AND THE NORTH CENTRAL USA WHILE A STRONG RIDGE PREVAILS NEAR 140W. TEMPERATURES: THE MONTH THROUGH THE FIRST 22 DAYS IS AVERAGING 9 TO 11 DEGREES BELOW NORMAL. CALENDAR DAY AVERAGES PROJECT 10 BELOW WEDNESDAY, 15 TO 20 BELOW THURSDAY THROUGH SATURDAY, MAYBE 10 BELOW SUNDAY AND THEN NEAR NORMAL NEXT MONDAY. FORECAST BASIS: UNLESS OTHERWISE NOTED, 50 50 BLEND 12Z/23 GFS/NAM MOS GUIDANCE TUESDAY NIGHT-WEDNESDAY NIGHT, 12Z/23 MEX MOS THURSDAY AND THURSDAY NIGHT THEN THE 15Z/23 WPC GRIDDED ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT-SKY-WIND FROM FRIDAY-NEXT MONDAY. THE DAILIES BELOW... TUESDAY NIGHT-WEDNESDAY: FAIR SKIES AHEAD OF THE NEXT CFP. DESPITE AN INCREASING BL WIND LATE TUE NIGHT THAT SHIFTS TO WNW WEDNESDAY...RADIATIONAL COOLING DECOUPLING ANTICIPATED OVER THE SNOW COVERED COUNTRYSIDE OF AT LEAST NJ AND AND E PA. 2M TEMPS FROM THE 12Z/23 GFS ARE PROBABLY EXCELLENT AND MUCH BETTER PREDICTORS OF THOSE RADIATIONAL COOLING SITES SUCH AS FWN SMQ UKT AND EVEN MIV/ACY. HAVE FORECAST WELL BELOW GUIDANCE IN THOSE LOCATIONS. OTRW...CLOUD COVER SHOULD BE MORE COMMON VCNTY KMPO WHERE FLURRIES MAY OCCUR NEAR AND AFT CFP WEDNESDAY. THE COLD FRONT IS FORECAST TO MOVE THRU THE AREA EITHER LATE IN THE AFTERNOON OR IN THE EVENING ON WEDNESDAY. NORTHWEST WINDS WILL ADVECT COLDER AIR INTO THE REGION ON GUSTY WEST TO NORTHWEST WINDS OF 25 MPH, THOUGH THIS NEXT ARCTIC BLAST NOT QUITE AS EXTREME AS ITS PREDECESSORS. WEDNESDAY NIGHT-THURSDAY...A LITTLE MORE INTERESTING AS ENSEMBLES ARE HINTING AT A BRUSH WITH SNOW AS THE SOUTHERN STREAM SHORT WAVE LAUNCHES ANOTHER SFC LOW NEAR CAPE HATTERAS, WHICH IS MODELED TO MOVE NE OUT TO SEA. THE SREF AND GEFS HAVE DECENT PROBS FOR A PERIOD OF SNOW WITH THIS FEATURE WEDNESDAY NIGHT, ESPECIALLY DE/COASTAL S NJ. THE 23/15Z SREF HAS A 60 PROB FOR 1 INCH SE OF I-95 AND A 20 POP FOR 4 INCHES DELAWARE AND THE SE NJ COAST. NORTHWEST TO NORTH WINDS GUSTS TO 20 MPH. THE 330 PM FCST MAY BE TOO CONSERVATIVE FOR SE DE AND CAPE MAY NJ. THIS NEEDS TO BE MONITORED FOR A POTENTIAL AREA OF CONSIDERABLE UPGRADE IN FUTURE FORECASTS. IE..HIGHLY UNCERTAIN ATTM. THURSDAY NIGHT THROUGH SATURDAY...EXPANSIVE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL BUILD INTO THE NORTHERN MID-ATLANTIC REGION BY SATURDAY. IT MAY AWAIT A SECOND LOW DEVELOPING OFF THE MID ATLANTIC COAST TO BRUSH OUR COASTAL AREA WITH LIGHT SNOW BUT FOR NOW, WE EXPECT THIS LATTER LOW TO BE WEAKER AND FURTHER OUT TO SEA THAN THE WEDNESDAY NIGHT - THURSDAY MORNING LOW. A BRISK NORTHERLY AND NOTABLE CAA FLOW WITH GUSTS AROUND 20 MPH IS EXPECTED THURSDAY THROUGH FRIDAY WITH LIGHT WIND SATURDAY. HIGH BAROMETRIC PRESSURE IS ANTICIPATED HERE ON SATURDAY. SUNDAY-MONDAY...THE HIGH MOVES OFFSHORE SUNDAY AND CHANCES FOR WINTRY PRECIP INCREASE CONSIDERABLY AHEAD OF THE NEXT COLD FRONT BY SUNDAY NIGHT WITH MONDAY SUBJECT TO CONSIDERABLE WARMING ALOFT. STILL TOO FAR OUT AND TOO MUCH UNCERTAINTY TO OFFER MUCH DETAIL. REMEMBER THE EARLY MODEL CYCLES OF LAST WEEK (00Z/17 AND 00Z/18 GUIDANCE FOR THIS PAST SATURDAY`S WINTRY PCPN THAT WAS SUPPOSED TO CHANGE TO RAIN EVERYWHERE WITH A BIG WARMUP THAT DIDN`T HAPPEN NEARLY AS AGGRESSIVELY. FORTUNATELY THE MODELS GAVE UP ON THE BIG WARMING SHORTLY AFTER THE 00Z/18 CYCLE. LIGHT WIND SUNDAY PROBABLY REDUCES WARMING MIXING POTENTIAL AS DOES CONSIDERABLE CLOUD COVER AND THE THREAT OF PRECIPITATION. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TONIGHT...VFR. NORTH-NORTHWEST WINDS AROUND 10 KNOTS, BECOMING LIGHT AND VARIABLE OVERNIGHT AT MOST TERMINALS. TUESDAY...VFR, WITH SOME INCREASE IN MID TO HIGH LEVEL CLOUDS IN THE AFTERNOON. LIGHT AND VARIABLE WINDS EARLY, BECOMING SOUTH-SOUTHEAST LESS THAN 10 KNOTS. OUTLOOK... TUESDAY NIGHT AND WEDNESDAY...PREDOMINATELY VFR. ISO SHSN, MAINLY POCONOS WEDNESDAY. WNW WINDS 10-15 KT WILL GUST TO 25 KT ON WEDNESDAY. WEDNESDAY NIGHT THROUGH FRIDAY...VFR AND MODEST NLY WINDS GUSTING TO 20 KT AT TIMES. SMALL CHANCE OF IFR SNOW EARLY THURSDAY VCNTY KACY. SATURDAY...VFR. LIGHT NW WIND. && .MARINE...
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ARCTIC HIGH PRESSURE WILL BUILD ACROSS THE AREA THROUGH THE OVERNIGHT, THEN SHIFT OFFSHORE TUESDAY. THIS WILL ALLOW THE PRESSURE GRADIENT TO CONTINUE TO RELAX AND THEREFORE THE WINDS WILL BE DIMINISHING. THIS IS ALREADY OCCURRING AS THE WINDS ARE GRADUALLY COMING DOWN ACROSS DELAWARE BAY THIS EVENING. HOWEVER, WINDS ARE STILL GUSTING JUST ABOVE 25KT ON THE ATLANTIC COASTAL WATERS. THUS HAVE EXTENDED THE SCA THERE THROUGH 4 AM. ONCE THE WINDS DROP OFF BELOW ADVISORY LEVELS, THEY WILL REMAIN SO THROUGH TUESDAY. AS TEMPERATURES REMAIN WELL BELOW FREEZING OVERNIGHT, MODERATE FREEZING SPRAY IS EXPECTED FOR A TIME AND THEREFORE THE FREEZING SPRAY ADVISORY CONTINUES. OUTLOOK... TUESDAY NIGHT AND WEDNESDAY...SW WINDS TUESDAY NIGHT AND W-NW WINDS WEDNESDAY PROBABLY GUST AROUND 20 KT. MARGINAL SCA CRITERIA POSSIBLE. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT... WINDS TURN NLY AND INCREASE TO AROUND 20 KT WITH NEAR SCA LEVELS. MODERATE FREEZING SPRAY IS ALSO POSSIBLE AS WINDS AND WAVES INCREASE THURSDAY INTO FRIDAY. FRIDAY AND SATURDAY...NO HEADLINES ON DELAWARE BAY WITH LIGHT NORTHERLY FLOW BUT THE PERSISTENT NNE FETCH OF COLD AIR OVER RELATIVELY WARM SST (IF YOU CONSIDER SST IN THE LOWER 30S WARM) MAY FORCE HAZARDOUS 5-6 FT 6 SECOND NE SWELLS?
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&& .CLIMATE... THE FORECAST LOW TEMPERATURES FOR TUESDAY, FEBRUARY 24TH PUTS SEVERAL DAILY LOW TEMPERATURE RECORDS IN JEOPARDY. THE PARTICULARS... POR / SITE / RECORD LOW FEB 24 / FCST LOW FEB 24 1872 / KPHL / 2F (1889) / 3F 1874 / KACY / 2F (1889) / -3F 1894 / KILG/ 6F (1923) / 2F 1922 / KABE/ 4F (1948) / -5F 1869 / KRDG / 3F (1914) / -5F 1865 / KTTN / -2F (1889,1873) / -1F 1948 / KGED / 13F (1956) / 7F 1901 / KMPO /-14F (1914) / -12F NOTE: POR = PERIOD OF RECORD, THE YEAR OFFICIAL CLIMATE OBS BEGAN. THE FOLLOWING IS A TABLE OF THE ***PROJECTED*** TOP 5 COLDEST FEBRUARY`S ON RECORD, BASED ON THE CURRENT FORECAST, AND THUS SUBJECT TO CHANGE. EACH RANKING DENOTES THE MEAN FEBRUARY TEMPERATURE /F/ AND YEAR OF OCCURRENCE. POR / SITE / 1ST RANK / 2ND RANK / 3RD RANK / 4TH RANK / 5TH RANK 1872 / KPHL / 22.2(1934) 23.0(1979) 24.3(1885) 24.6(1978) 25.3(2015) 1874 / KACY / 21.6(1979) 23.6(2015)*23.8(1978) 25.5(1875) 25.7(1905) 1894 / KILG / 20.2(1934) 22.1(1979) 22.7(1978) 24.1(2015) 24.9(1936) 1922 / KABE / 16.6(1934) 18.5(2015) 20.4(1979) 21.6(1936) 22.0(1963) *KACY TIED WITH 1934 FOR THE PROJECTED SECOND COLDEST FEBRUARY. PER THE ABOVE TABLE, BOTH ABE AND ACY ARE ON TRACK FOR THE SECOND COLDEST FEBRUARY, FOLLOWED BY THE FOURTH COLDEST AT ILG, AND THE FIFTH COLDEST AT PHL. THE FOLLOWING IS A TABLE OF THE ***PROJECTED*** MEAN FEBRUARY 2015 TEMPERATURES /F/ AND DEPARTURES FROM NORMAL. THIS IS ALSO BASED ON THE CURRENT FORECAST, AND THUS SUBJECT TO CHANGE. JANUARY 2015 MEAN TEMPERATURES ARE ALSO INCLUDED FOR COMPARISON PURPOSES. POR / SITE / FEB MEAN(F) / FEB NORMAL(F) / DEPARTURE / JAN MEAN(F) 1872 / KPHL / 25.3 / 35.7 / -10.4 / 30.9 1874 / KACY / 23.6 / 35.3 / -11.7 / 30.2 1894 / KILG/ 24.1 / 35.1 / -11.0 / 30.3 1922 / KABE/ 18.5 / 30.7 / -12.2 / 25.9 IN GENERAL, MEAN TEMPERATURES AT OUR FOUR MAJOR CLIMATE SITES ARE ON TRACK TO BE AROUND 10 TO 12 DEGREES BELOW NORMAL FOR FEBRUARY 2015. IT`S ALSO INTERESTING TO NOTE THAT THE PROJECTED FEBRUARY 2015 MEAN TEMPERATURES WILL BE WELL BELOW THE JANUARY 2015 MEAN TEMPERATURES. TO PUT THIS IN PERSPECTIVE, NORMAL MEAN FEBRUARY TEMPERATURES AT OUR FOUR MAJOR CLIMATE SITES ARE ABOUT 2 TO 3 DEGREES WARMER THAN JANUARY. THE OPPOSITE IS SHAPING UP FOR FEBRUARY 2015. && .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ054- 055. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR ANZ450>455. FREEZING SPRAY ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ430- 431-450>455.
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&& $$ SYNOPSIS...DRAG/GORSE NEAR TERM...GORSE SHORT TERM...ROBERTSON LONG TERM...DRAG AVIATION...DRAG/GORSE MARINE...DRAG/GORSE/JOHNSON/ROBERTSON CLIMATE...DRAG/FRANCK

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