Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 250857 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 357 AM EST TUE NOV 25 2014 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD INTO THE REGION TODAY FROM THE SOUTHWEST. THEN, A STORM IS EXPECTED TO DEVELOP OFF THE SOUTHEASTERN UNITED STATES TONIGHT AND STRENGTHEN AS IT MOVES NORTHEASTWARD. THIS SYSTEM WILL IMPACT OUR REGION ON WEDNESDAY BEFORE REACHING THE CANADIAN MARITIMES ON THANKSGIVING MORNING. A LARGE ARE OF HIGH PRESSURE WILL THEN BUILD IN FROM THE CENTRAL PART OF THE NATION FOR FRIDAY THROUGH SATURDAY BEFORE IT MOVES OFFSHORE ON SUNDAY. A COLD FRONT ASSOCIATED WITH AN AREA OF LOW PRESSURE IN EASTERN CANADA WILL CROSS THE REGION SUNDAY OR MONDAY.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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A COLD FRONT CONTINUES TO SLIDE CLOSER TO THE COAST. ONCE IT MOVES OFF SHORE, IT SHOULD STALL. WHERE EXACTLY IT WILL STALL WILL HAVE AN IMPACT ON RAIN CHANCES FOR COASTAL LOCATIONS IN SOUTHERN DE AND NJ. FOR NOW HAVE ONLY INCLUDED SLIGHT CHANCE AND LOW END CHANCE MENTION ON LAND AS THERE IS A RATHER ROBUST SOUTHWESTERLY LOW LEVEL JET BEHIND THE FRONT. THOUGH NOT THE MOST DRAMATIC TEMPERATURE GRADIENT WITH A FALL COLD FRONT, TEMPERATURES TODAY ARE EXPECTED TO BE ABOUT 15 DEGREES LOWER THAN YESTERDAY, BUT STILL ABOVE NORMAL.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TODAY/...
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EXPECTING THE COASTAL LOW TO LIFT NORTHEAST ALONG THE STALLED FRONT THROUGH THE OVERNIGHT HOURS, AND WILL BE OFF SHORE OF THE CAROLINAS BY EARLY WEDNESDAY MORNING. AS IT DOES LIFT NORTH THROUGH THE NIGHT, EXPECT TO SEE PRECIPITATION ASSOCIATED WITH THE LOW BEGIN TO MOVE INTO OUR REGION AFTER MIDNIGHT. FOR THE MOST PART HOWEVER, THROUGH THIS PERIOD, GIVEN THE STRAIGHT ON SHORE FLOW, IT SHOULD BE RAIN. THE ONE EXCEPTION IS IF...AND THAT IS A BIG IF...THE PRECIPITATION CAN REACH THE HIGHER TERRAIN OF THE POCONOS AND NW NJ THROUGH THE OVERNIGHT HOURS. HOWEVER, EVEN IN THAT CASE, WITH THE CENTER OF THE LOW STILL SO FAR AWAY, DO NOT EXPECT SIGNIFICANT PRECIP AMOUNTS, AND THUS DO NOT EXPECT SIGNIFICANT ACCUMULATING SNOW BEFORE SUNRISE.
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&& .LONG TERM /TONIGHT THROUGH MONDAY/...
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...WE CONTINUE TO TRACK A STORM WHICH WILL IMPACT THE BUSY TRAVEL TIME ON WEDNESDAY... MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT OVERALL ON THE EVOLUTION OF A STORM WHICH WILL DEVELOP OFF THE SERN CONUS CST ON WED THEN TRACK NEWD DURG THE DAY ON WED. HOWEVER, WHILE THERE IS GOOD AGREEMENT ON THE SYNOPTIC FEATURES, THERE REMAINS SOME DISAGREEMENT ON THE THERMAL PROFILES AND SOME THE FINER DETAILS, WHICH COULD PROVE IMPORTANT AS THE EVENT PLAYS OUT. IT CONTINUES TO APPEAR AS THE AREAS N AND W OF PHILADELPHIA HAVE THE BEST SHOT OF SEEING SIGNIFICANT SNOW, WHICH WILL IMPACT TRAVEL. SRN AND ERN AREAS WILL LIKELY STAY ALL OR MOSTLY RAIN, SOME OF WHICH COULD BE HEAVY AT TIMES. THE POTENTIAL FOR SOME PONDING OF RAIN ON ROADWAYS AND POOR DRAINAGE AREAS IS POSSIBLE IN THESE LOCATIONS. THE BIGGEST QUESTION MARK IS WHAT HAPPENS ALONG THE I-95 CORRIDOR. TEMPS LOOK MARGINAL. CERTAINLY ABOVE FREEZING AT THE START OF THE EVENT, COOLING DURING IT, BUT HOW MUCH. MODEL GUID VARIES AS TO WHAT DEW POINTS WILL BE, AND HENCE WHEN THE PRECIP START WHERE THE WET BULB ZERO WILL BE. A DEGREE OR TWO CAN MAKE A WORLD OF DIFFERENCE HERE. ADDITIONALLY, IT WAS QUITE WARM ON MONDAY AND WILL BE FAIRLY WARM TODAY SO THE GROUND HAS IS WARM WHICH MAY NEGATE SOME ACCUMS, ESPECIALLY AT THE ONSET ON ROADWAYS ETC, UNLESS THE SNOW COMES DOWN HEAVY. THE ECMWF WAS OUT AHEAD OF THIS SYS (NO SURPRISE!). WHILE THE OTHER MDLS OFFERED VARIOUS SOLNS OVER THE COURSE OF THE LAST FEW DAYS, THE ECMWF ALWAYS HAD A ROBUST SYS AND NEVER WAVERED MUCH FROM ITS TRACK. HOWEVER, IT HAS ALSO CONSISTENTLY BEEN WARMER AS WELL, WHICH IS DIFFICULT TO IGNORE. SO, ULTIMATELY IT REMAINS TO BE SEEN WHAT WILL WIN OUT IN THIS AREA. THERE IS ALSO THE POTENTIAL FROM THE I-95 CORRIDOR N AND W FOR SOME MESOSCALE BANDING WHICH COULD INCREASE ANY SNOWFALL RATES, BUT THIS IS OFTEN DIFFICULT TO PREDICT MORE THAN A FEW HOURS IN ADVANCE, AND AMOUNTS CAN VARY WIDELY BETWEEN THOSE AREAS UNDER A BAND AND THOSE WHICH ARE NOT. WITH THE MRNG PKG, ALL HEADLINES WILL BE LEFT IN PLACE UNCHANGED. THE MOST LIKELY PLACES TO REACH HEADLINE CRITERIA WOULD BE EXTREME NRN NJ AND THE POCONOS. THE FURTHER S ONE GETS IN THE WATCH, CONFIDENCE FALLS QUICKLY, BUT WILL WAIT OTHER GUIDANCE BEFORE MAKING OTHER CHANGES TO HEADLINES. ULTIMATELY, SOME OF THE WATCH WILL PROBABLY BECOME WARNINGS, SOME MAY BECOME ADVISORIES AND SOME MAY BE DROPPED. ALSO, WHEN PRECIP BEGINS ON WED, IT WILL LIKELY BE RAIN VIRTUALLY EVERYWHERE AND WILL MIX AND CHANGE FROM NW TO SE, WHICH OF COURSE IS HIGHLY DEPENDENT ON TEMPS. FURTHERMORE, LTST GUID INDICATES THAT ALL PRECIP WILL BE ENDING DURG WED EVE. THE COMBINATION OF ALL OF THESE FACTORS CAME UP WITH SLIGHTLY LOWER SNOW TOTALS THIS MORNING. THE AFOREMENTIONED STORM MOVES OUT WED NIGHT AND AND A DRY FCST IS EXPECTED BY THE TIME EVERYONE SITS DOWN FOR TURKEY. HIGH PRESSURE WILL BUILD IN FROM THE MIDDLE OF THE COUNTRY FOR FRI THRU EARLY SUN WHICH WILL YIELD CONTINUED DRY WX AND A WARMING TREND, AS THE HIGH MOVES EWD BY SUN AND SWLY FLOW RETURNS. LOW PRES WILL MOVE ACRS ERN CANADA ON SUN AND ITS ASSOCD CDFNT WILL CROSS THE REGION SUN NIGHT OR ERLY MON, BRINGING ANOTHER SHOT OF PRECIP, MAINLY IN THE FORM OF RAIN. GUID IS NOW SUGGESTING THAT A WAVE COULD FORM ON THIS FRONT ON MON, WHICH WOULD LINGER PRECIP CHCS.
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&& .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS SHOULD CONTINUE THROUGH AT LEAST 00Z. THROUGH THIS TIME, EXPECT ONLY HIGH CLOUDS WITH CEILINGS ABOVE 10000 FT AGL. THE ONE EXCEPTION TO THIS IS KMIV AND POSSIBLY KACY, WHICH COULD SEE TRANSIENT CLOUDS BETWEEN 2000 AND 3000 FT AGL THROUGH 12Z. WESTERLY WINDS COULD GUST TO 20KT AT TIMES THROUGH THE DAY. AFTER 00Z...CEILINGS SLOWLY START TO LOWER. MOST TAF SITES FROM THE DELAWARE RIVER VALLEY AND FURTHER WEST (KPHL, KILG, KPNE, KTTN, KABE, AND KRDG) WILL LIKELY SEE CEILINGS STAY IN THE VFR RANGE THROUGH 12Z. AT KMIV AND KACY HOWEVER, THEY COULD SEE MVFR CEILINGS MOVE IN BETWEEN 06 AND 12Z. IN ADDITION TO LOWER CEILINGS, AREAS OF -RA COULD BEGIN TO MOVE IN AFTER 00Z AS WELL. HOWEVER, IT IS UNLIKELY THAT ANY TAF SITES WILL BE AFFECTED BEFORE 06Z, AND UNLIKELY THAT ANY OF THE INLAND TAF SITES WILL SEE ANY BEFORE 12Z. IF RA DOES MOVE IN, COULD SEE VISIBILITIES REDUCED TO MVFR AT TIMES. OUTLOOK.... WED AND WED EVENING... A VERY BUSY TRAVEL DAY, AND UNFORTUNATELY A TIME WHICH WILL BE IMPACTED BY A COASTAL STORM. THIS STORM WILL BRING WIDESPREAD MVFR AND IFR CONDS, MAINLY WITH CIGS BUT SOME VSBY RESTRICTIONS AS WELL, ESPECIALLY IN THOSE AREAS THAT SEE SNOW OR HVY RAIN. FOR NRN AND WRN AREAS (KABE/KRDG)...MOSTLY SNOW IS EXPECTED. ALONG THE I-95 CORRIDOR, THE PRECIP WILL START OFF AS RAIN, WITH TEMPS ABV FREEZING THEN WILL MIX WITH SNOW AND CHANGE OVER AT SOME POINT WED AFTN OR EVE BEFORE ENDING. FOR SRN AND ERN AREAS PRECIP WILL BE MOSTLY OR ALL RAIN. WIND WILL GUST IN THE 15 TO 25 KT RANGE AS WELL, MAINLY FROM THE N. PRECIP SHUD END DURG WED EVE. CONFIDENCE IS HIGH ABOUT THE EVENT, BUT LOW ABOUT PRECIP TYPE ALG THE I-95 CORRIDOR. THU...CONDS RETURN TO VFR AND WINDS SHIFT TO WESTERLY OR NORTHWEST. THERE COULD BE BRIEF MVFR CONDITIONS IN SCATTERED SNOW SHOWERS LATER THURSDAY MAINLY JUST N OF KRDG AND KABE. WINDS MAY GUST TO 25 KT. FRI THRU SAT...VFR CONDITIONS EXPECTED.
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&& .MARINE...
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WINDS AND SEAS WILL BE SLOW TO DECREASE ONCE THE COLD FRONT MOVES OFF SHORE BY SUNRISE. ONCE WINDS AND SEAS DO FALL BELOW SCA CRITERIA THIS MORNING ON THE BAY, AND LATE THIS AFTERNOON ON THE ATLANTIC COASTAL WATERS, THERE WILL BE A BRIEF LULL WITH SUB SCA CONDITIONS BEFORE NORTHEASTERLY WINDS INCREASE QUICKLY AFTER MIDNIGHT IN RESPONSE TO THE APPROACHING LOW. BY EARLY TOMORROW MORNING, GALE CONDITIONS ARE LIKELY ON THE LOWER DELAWARE BAY AND THE ATLANTIC COASTAL WATERS. OUTLOOK... WED...A GALE WARNING HAS BEEN RAISED FOR THE COASTAL WATERS AND DELAWARE BAY AS AN AREA OF LOW PRESSURE MOVES BU OFFSHORE. WED NIGHT...GALE CONDITIONS WILL CONTINUE EARLY, THEN SEAS AND WIND WILL DECREASE AND AND SCA WILL BE LIKELY NEEDED. THU...WIND AND SEAS CONTINUE TO DIMINISH BUT SCA WILL BE NEEDED PROBABLY THU AFTN OR EVE. FRI THROUGH SAT..WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA.
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&& .CLIMATE...
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REGARDING THE MIDWEEK COASTAL STORM BRINGING SNOW TO A LARGE PORTION OF OUR REGION, WE HAVE INCLUDED DAILY SNOWFALL RECORDS BELOW FOR OUR FOUR PRIMARY CLIMATE SITES THAT HAVE A LONG-STANDING UNBROKEN PERIOD OF RECORD (POR) WITH RESPECT TO HISTORICAL SNOWFALL DATA. DAILY SNOWFALL RECORDS: NOVEMBER 26TH: NOVEMBER 27TH: PERIOD OF RECORD: ACY: TRACE 1977,1957,1955 1.2 INCHES 1978 1874 PHL: 6.0 INCHES 1898 6.9 INCHES 1949,1938 1872 ILG: 0.1 INCHES 1950 4.5 INCHES 1978 1894 ABE: 1.7 INCHES 1925 7.0 INCHES 1938 1922 OTHER COOPERATIVE SITE SHORTER HISTORICAL RECORD CAN BE FOUND AT THE NWS MOUNT HOLLY WEBSITE UNDER NOW DATA.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR PAZ054-055. WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR PAZ060>062-101-103-105. WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR PAZ070-071-102-104-106. NJ...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR NJZ001-007-008. WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR NJZ009. WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR NJZ010-015. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ450>455. GALE WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR ANZ431- 450>455. SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ430-431.
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&& $$ SYNOPSIS...NIERENBERG NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...NIERENBERG AVIATION...JOHNSON/NIERENBERG MARINE...JOHNSON/NIERENBERG CLIMATE...

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