Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 242132 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 432 PM EST TUE FEB 24 2015 .SYNOPSIS... HIGH PRESSURE IS SHIFTING OFFSHORE. LOW PRESSURE ALONG THE SOUTHEAST COAST OF THE UNITED STATES SCOOTS NORTHEASTWARD OUT TO SEA WEDNESDAY. A COLD FRONT WILL PASS ACROSS OUR AREA LATE WEDNESDAY, AS A MORE POTENT LOW PRESSURE SYSTEM ALONG THE GULF COAST HEADS NORTHEAST. THAT LOW RACES OUT TO SEA WELL TO OUR EAST ON THURSDAY. STRONG ARCTIC HIGH PRESSURE CENTERED IN MONTANA WILL ARRIVE ALONG THE MID ATLANTIC COAST THIS COMING WEEKEND, THEN A COLD FRONT PROBABLY CROSSES OUR AREA SUNDAY NIGHT OR MONDAY. A MORE IMPORTANT AREA OF LOW PRESSURE SHOULD APPROACH FROM THE SOUTHWEST ON TUESDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... TWO SYSTEMS OF CONCERN TONIGHT, ALTHOUGH NEITHER IS EXPECTED TO BRING SIGNIFICANT WEATHER TO THE AREA. FIRST IS THE LOW PRESSURE SYSTEM WELL TO OUR SOUTH OFF THE SOUTHEAST COAST. THIS ACTUAL LOW WILL REMAIN WELL SOUTH OF THE AREA, BUT AS THE SOUTHERN STREAM SHORT WAVE MOVES OFF THE COAST, A SECONDARY AREA OF LOW PRESSURE IS FORECAST TO DEVELOP NORTH OF THE MAIN LOW, AND TRACK TO OUR EAST AND NORTHEAST. EVEN THIS SECONDARY LOW LOOKS TO STAY FAR ENOUGH EAST OF THE AREA THAT MOST OF ITS PRECIPITATION SHOULD STAY OFFSHORE, ALTHOUGH IT MAY BRING SOME VERY LIGHT PRECIPITATION TO OUR EXTREME SOUTH AND COASTAL AREAS. THE ONLY PLACES THAT MIGHT GET SOME LIGHT SNOW ON THE OUTSKIRTS OF THE SYSTEM WOULD BE SOUTHERN DELAWARE AND COASTAL NEW JERSEY, SO WE KEEP A SLIGHT CHANCE OF SNOW HERE. NO ACCUMULATION IS EXPECTED. THE SECOND IS A FRONTAL BOUNDARY ASSOCIATED WITH LOW PRESSURE MOVING ACROSS SOUTHERN CANADA OVERNIGHT. THERE IS NOT MUCH SIGNIFICANT MOISTURE ASSOCIATED WITH THE SYSTEM. THE MAIN VORTICITY WITH THE SHORT WAVE ALOFT IS FORECAST TO PASS NORTH OF THE AREA, BUT OUR FAR NORTHERN AREAS MAY BE CLOSE ENOUGH THAT SOME SNOW SHOWERS MAY DEVELOP, SO WE INCLUDE A SLIGHT CHANCE HERE AS WELL. OVERNIGHT LOWS ARE EXPECTED WARMER THAN LAST NIGHT, BUT WILL STILL BE 10-15 DEGREES BELOW NORMAL. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... A SECONDARY COLD FRONT WILL PUSH THROUGH THE AREA DURING THE DAY WEDNESDAY. NO PRECIPITATION IS EXPECTED DURING THE DAY WITH THE FRONT. THE FRONT WILL HELP INCREASE WINDS ACROSS THE AREA, WITH WINDS GUSTING AROUND 20-25 MPH AT TIMES DURING THE DAY. THE GOOD NEWS IS HIGHS WILL BE ABOUT 10 DEGREES WARMER THAN TODAY, BUT WITH THE WIND IT WILL FEEL COLDER. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... 500MB: PREDOMINANTLY WEST OR WEST SOUTHWEST FLOW THROUGH EARLY NEXT WEEK. A SHORT WAVE IN THE SOUTHERN STREAM WEDNESDAY NIGHT ZIPS ENE OFF THE MID ATLANTIC COAST INTO THE CONFLUENCE ZONE WITH THE NORTHERN STREAM. SEVERAL WEAK SHEAR RELATED SHORT WAVES CROSS THE AREA THEREAFTER BUT ARE GENERALLY DRY DUE TO THE OVERWHELMING SUBSIDENCE ASSOCIATED WITH THE APPROACHING ARCTIC HIGH. EARLY NEXT WEEK THERE SHOULD BE A MUCH MORE SUBSTANTIAL WARM AIR ADVECTION PRECIPITATION PATTERN WITH A MODELED 180 KT 250 MB JET CORE OVER MAINE...RRQ FOR OUR AREA ON TUESDAY. TEMPERATURES...WE HOPE THE CLIMATE SECTION HAS CONSIDERABLE USEFUL INFORMATION NOT ONLY FOR FEBRUARY BUT ALSO A COMPARISON TO JANUARY AND THE HISTORICAL DATABASE. CALENDAR DAY TEMPERATURES THURSDAY-SATURDAY SHOULD AVERAGE 14 TO 20 DEGREES BELOW NORMAL. THEN 10 TO 15 DEGREES BELOW NORMAL SUNDAY; 0 TO 5 BELOW NORMAL MONDAY AND NEAR NORMAL TUESDAY AS WE DELAY THE WARMING 24 HOURS EACH DAY WE DO THIS AFTERNOON EXTENDED PRODUCT. FORECAST BASIS: UNLESS OTHERWISE NOTED, 50 50 BLEND 12Z/24 GFS/NAM MOS GUIDANCE WEDNESDAY NIGHT-THURSDAY NIGHT, 12Z/24 MEX MOS FRIDAY AND FRIDAY NIGHT THEN THE 15Z/24 WPC GRIDDED ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT-SKY-WIND FROM SATURDAY-NEXT TUESDAY. THE DAILIES BELOW... WEDNESDAY NIGHT-THURSDAY...WATCHING THE NW EXTENT OF THE SNOW SHIELD ASSOCIATED WITH THE SOUTHERN STREAM SHORT WAVE WHICH SHOULD FOR THE MOST PART PASS OUT TO SEA WITH ONLY A LITTLE SNOW FOR POSSIBLY SRN DELAWARE AND THE SOUTHERN TIP OF NJ. THERE SHOULD BE QUITE A BIT OF CLOUD COVER NW OF THE SNOW SHIELD BUT FOR NOW THE THINKING IS DRY AIR BELOW 5000 FT SHOULD RENDER THE NORTHERN EDGE OF THE .01 AS VIRGA. DESPITE LACK OF ATLANTIC EASTERLY INFLOW AT OUR LATITUDE THIS NEEDS TO BE MONITORED FOR A SLIGHTLY LARGER RESPONSE THAN NOW FORECAST. WE`VE MAINTAINED CONSIDERABLE CONTINUITY WITH THE MID SHI9FT FORECAST. YOU`LL NOTE A CHANCE OF SNOW SHOWERS FURTHER N ACROSS E PA AND WESTERN NJ ON THURSDAY BUT FOR NOW MY CONFIDENCE IN THAT OCCURRENCE IS WELL BELOW AVERAGE. THIS SHORT WAVE PASSAGE HOLDS UP THE ARRIVAL OF THE ARCTIC AIRMASS. N-NE WIND WEDNESDAY NIGHT AND THURSDAY MORNING WITH GUSTS 15-20 MPH ALONG AND SE OF I95. CONFIDENCE ON THE OVERALL FORECAST SCENARIO FOR WEDNESDAY NIGHT- THURSDAY: AVERAGE. FRIDAY - SATURDAY...HIGH PRESSURE WILL BE IN CONTROL OVER THE REGION WITH ZONALISH FLOW ALOFT TAKING SHAPE. A COUPLE MORE WELL BELOW AVERAGE TEMPERATURE DAYS ARE EXPECTED. PARTLY CLOUDY SKIES ARE ANTICIPATED BOTH DAYS WITH NORTHERLY GUSTS AROUND 20 MPH AND LESS OF A NORTHERLY WIND SATURDAY. ITS NOT IMPOSSIBLE TO SEE SOME FLURRIES HERE AND THERE FRIDAY BUT FOR NOW THESE ARE NOT IN THE FORECAST. AS THE HIGH CRESTS OVER OUR AREA SATURDAY BAROMETRIC PRESSURE SHOULD RISE CLOSE TO 30.8 INCHES. RADIATIONAL COOLING WILL PROBABLY RENDER MOS GUIDANCE LESS EFFECTIVE THAN THE APPLICATION OF THE GFS 2M TEMPS OVER THE COUNTRYSIDE LOCATIONS SUCH AS KPTW, KABE, KFWN, KSMQ, KMIV. CONFIDENCE ON THE OVERALL FORECAST SCENARIO FOR FRIDAY-SATURDAY: AVERAGE. SUNDAY...THICKENING CLOUDS AHEAD OF THE NEXT COLD FRONT. NOT NEARLY AS COLD AFTER A POSSIBLE VERY EARLY MORNING RADIATING RECORD LOW AT KACY? A PERIOD OF SNOW IS POSSIBLE IN THE AFTERNOON OR EVENING IN THE WAA PATTERN AHEAD OF THIS NEXT COLD FRONT. LOWERED THE MAX TEMPS AS FCST BY WPC WITH A BLEND OF THE 12Z/24 MEX AND EC 2M TEMPS. 2M TEMPS AGAIN MAY PROVE MORE USEFUL IN FORECASTING THE LOW TEMPS FOR THE NJ COUNTRYSIDE, PRIOR TO THE ARRIVAL OF WAA CLOUD COVER NEAR DAYBREAK. MINS MAY BE AT 12010AM SUNDAY. CONFIDENCE: AVERAGE. MONDAY...CFP POSSIBLY ACCOMPANIED BY A PERIOD OF PRECIPITATION, MAINLY EARLY. SEASONABLE. GUSTY NW WINDS POSSIBLE IN THE AFTERNOON? CONFIDENCE: BELOW AVERAGE NOT ONLY ANY PRECIPITATION OCCURRENCE AFTER 12Z BUT ALSO THE MAX TEMPS MIGHT BE FORECAST SEVERAL DEGREES TOO WARM. TUESDAY...JET DYNAMICS...WAA AND POOLING MOISTURE IN THE SOUTHERN UNITED STATES FAVOR THE DEVELOPMENT A HEAVY PRECIPITATION EVENT. TOO EARLY FOR DETAILS SINCE THE SYSTEM MAY END UP SLIGHTLY WEAKER AND THEREFORE COLDER AND FURTHER EAST. ESSENTIALLY A MIXED PCPN EVENT AT THIS DISTANT OUTLOOK. CONFIDENCE: AVERAGE OR ABOVE ON AN EVENT BUT ONLY AVERAGE OR BELOW ON THE THERMAL PROFILES. && .AVIATION /22Z TUESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE MOSTLY EXPECTED ACROSS THE TAF SITES. A PERIOD OF MVFR CIGS IS POSSIBLE AT ABE/RDG OVERNIGHT. THE REST OF THE SITES MAY EXPERIENCE SOME SCATTERED LOWER CLOUDS, BUT CIGS ARE EXPECTED TO REMAIN VFR. SOUTH-SOUTHEAST WINDS AROUND 5-10 KNOTS TODAY MAY BECOME LIGHT AND VARIABLE AT MANY LOCATIONS THIS EVENING, BEFORE SHIFTING TO THE SOUTHWEST BEHIND A FRONTAL BOUNDARY OVERNIGHT. DURING THE DAY WEDNESDAY, WEST-NORTHWEST WINDS WILL LIKELY BEGIN GUSTING AROUND 20 KNOTS DURING THE LATE MORNING INTO THE AFTERNOON. OUTLOOK... WEDNESDAY NIGHT - THURSDAY MORNING...VFR CIGS. GUSTY N WINDS TO 15 OR 20 KT POSSIBLE I95 EWD. POSSIBLE LIGHT MVFR/IFR SNOW SOUTH AND EAST OF PHL/ILG...COULD AFFECT MIV/ACY LATE THURSDAY MORNING BEFORE MOVING OUT TO SEA. THURSDAY AFTERNOON...VFR PARTIAL CLEARING. N WIND GUST 15-20KT. FRIDAY - SATURDAY...VFR. N WIND WIND GUST 15-20 KT FRIDAY AND LESS SATURDAY. SUNDAY...VFR CIGS. CHANCE OF MVFR CONDITIONS IN SNOW SUNDAY AFTERNOON OR NIGHT. CHANCE OF LIGHT WIND. && .MARINE... SOUTH-SOUTHEAST WINDS WILL BECOME MORE SOUTHERLY THIS EVENING, THEN SOUTHWEST-WEST OVERNIGHT AS A FRONTAL BOUNDARY MOVES ACROSS THE AREA. AS LOW PRESSURE LIFTS TO OUR NORTHEAST OVERNIGHT INTO WEDNESDAY, WINDS WILL INCREASE, ESPECIALLY AS A SECONDARY FRONTAL BOUNDARY MOVES ACROSS THE AREA DURING THE DAY WEDNESDAY. THE NORTHERN HALF OF THE ATLANTIC WATERS MAY BEGIN TO SEE SMALL CRAFT ADVISORY CONDITIONS AROUND DAYBREAK WEDNESDAY AND CONTINUE THROUGH THE DAY. SO A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NORTHERN HALF OF THE ATLANTIC WATERS. FOR THE SOUTHERN HALF OF THE ATLANTIC WATERS AND DELAWARE BAY, THESE AREAS MAY BE FAR ENOUGH AWAY FROM THE DEPARTING LOW THAT THE PRESSURE GRADIENT MAY NOT CONTRIBUTE ENOUGH TO CREATE SMALL CRAFT ADVISORY CONDITIONS, SO NO ADVISORY FOR THE REST OF THE AREA. OUTLOOK... WEDNESDAY NIGHT THROUGH THURSDAY... WINDS TURN NLY AND INCREASE TO AROUND 20-25 KT WITH SCA POSSIBLE AT LEAST OFF SNJ AND THE DE ATLC WATERS. ATLANTIC SEAS SHOULD BUILD TO 5 OR 6 FEET EAST OF S NJ AND OVER THE ATLC DELAWARE WATERS. FRIDAY - SATURDAY...SUB-SCA EXPECTED, THOUGH PERSISTENT NORTH NORTHEAST WINDS MAY ALLOW FOR BUILDING SEAS ACROSS OUR SOUTHERN ZONES TO SCA HAZARDOUS SEAS OF 5 FT WITH A SHORT 5 SEC PERIOD. COASTAL FLURRIES POSSIBLE FROM THE BACKEDGE OF OCEAN EFFECT, PRIMARILY DEPENDENT ON THE 925MB WIND DIRECTION. SUNDAY...NO MARINE HEADLINES ANTICIPATED. && .CLIMATE... THIS MORNINGS RECORDS AND THE NEXT TWO PRIME DAYS FOR RECORDS. ADDED KACY RER LOW FOR MARCH 1 AT THE END OF THIS SECTION WHERE RADIATIONAL COOLING MIGHT PERMIT A RECORD SUNDAY MORNING BEFORE WAA CLOUD COVER CUTS OFF THE COOLING. ALSO THIS SECTION PROBABLY WONT UPDATE WEDNESDAY BUT WILL UPDATE AGAIN THURSDAY AND FRIDAY MORNINGS. POR / SITE / RECORD LOW FEB 24 FEB 27 FEB 28 1872 / KPHL / 2F (1889) NONE 6 1900 9 1934 1874 / KACY / 2F (1889) NONE 7 1934* 2 1934 1894 / KILG / 6F (1923) EQUAL 5 1934 -5 1934 1922 / KABE / 4F (1948) -8RER -2 1963 -10 1934 1869 / KRDG / 3F (1914) -3RER 4 1934* 3 1934 1865 / KTTN / -2F (1889,1873)NONE 6 1934 1 1934 1948 / KGED / 13F (1956) 11RER 10 1963 8 1950 1901 / KMPO /-14F (1914) -16RER -9 1993 -15 1907 KACY RER FOR 3/1 IS 5 IN 1980. NOTE: * INDICATE AND OTHER YEARS. 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. WE REREVIEWED THESE PROJECTIONS LISTED BELOW USING THIS TUESDAY MORNINGS (24TH) MINS AND THE PHI FCST AS SEEN ON NDFD AND SFT`S. WE SEE PHL/ABE/ILG ALL VERY CLOSE TO YESTERDAYS PROJECTIONS. KACY CHANGED TO A WARMER PROJECTION HOWEVER THAT COULD YET REVERT BACK TO A COLDER MONTHLY AVERAGE DUE TO THE POTENTIAL FOR RADIATIONAL COOLING ON ONE OR 2 OF THE MORNINGS. 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) 25.1(2015) 1874 / KACY / 21.6(1979) 23.8(1978/1934) 24.5(2015) 25.5(1875)25.7(1905) 1894 / KILG / 20.2(1934) 22.1(1979) 22.7(1978) 24.2(2015) 24.9(1936) 1922 / KABE / 16.6(1934) 18.5(2015) 20.4(1979) 21.6(1936) 22.0(1963) PER THE ABOVE TABLE, BOTH ABE IS ON TRACK FOR THE SECOND COLDEST FEBRUARY, ATLANTIC CITY 3RD COLDEST 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 / 25.1 / 35.7 / -10.6 / 30.9 1874 / KACY / 24.5 / 35.3 / -10.8 / 30.2 1894 / KILG / 24.2 / 35.1 / -10.9 / 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. ALSO...OF INTEREST...THIS WOULD ALSO BE THE SECOND COLDEST MONTHLY MEAN TEMPERATURE ON RECORD AT ALLENTOWN SINCE RECORDS BEGAN IN 1922; FEBRUARY 1934 BEING THE COLDEST! PHL PROJECTS 12TH COLDEST MONTHLY MEAN SINCE RECORDS BEGAN IN 1873. ATLANTIC CITY 7TH COLDEST MONTHLY MEAN SINCE RECORDS BEGAN THERE IN 1874. WILMINGTON HAS MISSING DATA IN ITS DATABASE (1897-1916) AND SO WE DONT FOCUS AS MUCH ATTENTION ON THAT RECORD. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST WEDNESDAY FOR ANZ450-451. && $$ SYNOPSIS...DRAG NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...DRAG AVIATION...DRAG/ROBERTSON MARINE...DRAG/ROBERTSON CLIMATE...CORRECTED MPO LOW THIS MORNING 431

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