Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 052131 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 431 PM EST THU MAR 5 2015 .SYNOPSIS... A STORM SYSTEM WILL EXIT TO OUR EAST THIS EVENING, THEN ARCTIC HIGH PRESSURE BUILDS IN OVERNIGHT AND FRIDAY. THE HIGH WILL THEN SETTLE TO OUR SOUTH ON SATURDAY. A WEAK LOW PRESSURE SYSTEM WILL TRACK TO OUR NORTH LATE SUNDAY INTO MONDAY, PULLING A COLD FRONT ACROSS OUR REGION ON MONDAY. HIGH PRESSURE SHOULD THEN BUILD INTO THE AREA TUESDAY INTO WEDNESDAY, WITH THE NEXT COLD FRONT SCHEDULED TO ARRIVE LATER WEDNESDAY INTO THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FOR THE POCONOS AND NORTHWEST NJ, SNOW HAS ENDED AND THE WINTER WEATHER ADVISORY HAS BEEN ALLOWED TO EXPIRE. TOTAL ACCUMULATIONS OF A FEW INCHES OCCURRED WITH A SHARP CUTOFF AS YOU GO NORTH IN THIS REGION. FOR THE LEHIGH VALLEY, SNOW WILL BE ENDING BY SUNSET AND A WINTER STORM WARNING CONTINUES UNTIL 7PM. NUMEROUS REPORTS OF AROUND SIX INCHES HAVE COME IN WITH LOCALLY HIGHER TOTALS AND THESE HAVE BEEN REFLECTED IN THE STORM TOTAL WEB MAP. FOR CENTRAL NEW JERSEY AND THE PHILADELPHIA METRO REGION, A COUPLE MORE HOURS OF MODERATE, BRIEFLY HEAVY SNOW ARE POSSIBLE BEFORE ENDING SHORTLY AFTER SUNSET. TOTAL ACCUMULATIONS 6-8, ISOLATED HIGHER. IN THE DELMARVA AND SOUTHEAST NEW JERSEY, THE CHANGEOVER WAS SLOW THIS AFTERNOON AND THIS WILL CUT INTO THE ACCUMULATIONS OF SNOW AND SLEET. FAVORABLE ISENTROPIC LIFT AND 700MB FRONTOGENETICAL FORCING ARE TAKING PLACE RESULTING IN HEAVIER BANDING, SO NOT A DRASTIC REDUCTION IN TOTALS. SUSSEX AND CAPE MAY COUNTIES MAY HAVE THE HARDEST TIME REACHING WARNING CRITERIA (4-6 OR SO) WITH AREAS FURTHER NORTH ENDING UP WITH 6 INCHES OR SO. FOR ADDITIONAL SNOW MAINLY USED THE RAP AND WPC QPF AS A GUIDELINE AND TOOK INTO ACCOUNT CURRENT OBS TO MAKE THE SNOW TOTAL FORECASTS REFERENCED ABOVE. TEMPERATURES WILL TUMBLE ONCE SKIES CLEAR. THIS SHOULD TAKE PLACE FAIRLY QUICKLY AFTER THE SNOW ENDS GIVEN A STEEP DROP IN DEW POINTS AND CONSIDERABLE DRY AIR ADVECTION. RECORD LOWS ARE POSSIBLE, PLEASE SEE CLIMATE SECTION BELOW. LOW TEMPERATURES TONIGHT ARE COMPOSED OF MET/MAV AND THE MODELED TWO METER TEMPERATURES FROM THE GFS WHICH HAS DONE WELL AT NIGHT WITH SNOW COVER. WIND CHILLS ARE LIKELY TO FALL BELOW ZERO ACROSS MOST OF THE REGION, WITH THE POCONOS SEEING WIND CHILLS WHICH MAY GET CLOSE TO ADVISORY THRESHOLD FOR A FEW HOURS. GIVEN THE LIMITED WINDOW AND MARGINAL VALUES IN TERMS OF AND ADVISORY, WILL JUST CONTINUE MENTION IN THE HWO. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... SUNNY DAY WITH HIGH PRESSURE BUILDING IN ON FRIDAY BUT STILL COLD. DID GO A TOUCH WARMER THAN MAV/MET GIVEN THE COOL DAYTIME BIAS WITH SNOW COVER. OTHER ELEMENTS STRAIGHT MAV/MET. CONTINUED NORTHWESTERLY WINDS UNDER 10 MPH OR SO. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... THE OVERALL SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH FROM THE MIDWEST TO THE NORTHEAST AND MID ATLANTIC. AS SHORT WAVE ENERGY MOVES THROUGH THE FLOW, THIS FEATURE SHOULD AMPLIFY A LITTLE FOR A TIME OR TWO. THIS SHOULD EVENTUALLY WEAKEN AS ENERGY EJECTS ACROSS THE SOUTHERN PLAINS LATE IN THE WEEKEND AND EARLY NEXT WEEK, WITH A RIDGE POTENTIALLY BUILDING OFF THE SOUTHEASTERN U.S. COAST. THIS RESULTS IN THE UPPER-LEVEL FLOW TURNING MORE ZONAL NEXT WEEK. WE USED A MODEL BLEND FOR FRIDAY NIGHT THROUGH SUNDAY, THEN WENT WITH THE 12Z WPC GUIDANCE THEREAFTER. WE THEN MADE SOME ADJUSTMENTS AFTER ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR FRIDAY NIGHT AND SATURDAY...A SHORT WAVE TROUGH LOOKS TO SLIDE ACROSS THE AREA, HOWEVER A DRY AIRMASS RESULTS IN NO PRECIPITATION. AT THE SURFACE, HIGH PRESSURE BUILDS OVER THE AREA HOWEVER ITS CENTER SLIDES TO OUR SOUTH THROUGH SATURDAY. THIS WILL RESULT IN A GRADUAL RETURN FLOW BEING ESTABLISHED AND AFTER A VERY COLD START SATURDAY, SOME MODERATION IS EXPECTED IN THE AFTERNOON. FOR SUNDAY AND MONDAY...A SHORT WAVE IS FORECAST TO TRACK NEAR THE MIDWEST AND GREAT LAKES SUNDAY, THEN WELL TO OUR NORTH MONDAY. THIS WILL DRIVE WEAK LOW PRESSURE WELL TO OUR NORTH, HOWEVER A COLD FRONT IS FORECAST TO MOVE THROUGH DURING MONDAY. IT APPEARS THAT THE MOISTURE WILL BE LACKING WITH THIS FEATURE AS MUCH OF THE LIFT OCCURS WELL TO OUR NORTH. THERE COULD BE A SNOW SHOWER THOUGH SUNDAY NIGHT INTO MONDAY ACROSS THE FAR NORTHWEST. OTHERWISE, THE AIRMASS IS FORECAST TO CONTINUE TO MODIFY AS THE FLOW COMES MORE FROM THE WEST AND NOT THE NORTH. FOR TUESDAY AND WEDNESDAY...HIGH PRESSURE SHOULD SHIFT TO OUR EAST AS A COLD FRONT MOVES ACROSS THE MIDWEST AND THE GREAT LAKES. LOW PRESSURE APPEARS TO TRACK WELL TO OUR NORTH ONCE AGAIN, WITH A WARM FRONT LIFTING MOSTLY TO OUR NORTHWEST. WHILE THE FLOW LOOKS FAIRLY WEAK, ENOUGH WAA IS EXPECTED TO OCCUR TO ALLOW FOR FURTHER MODERATION OF THE AIRMASS WITH MANY AREAS GETTING INTO THE LOWER 50S WEDNESDAY AFTERNOON. THE COLD FRONT SHOULD BE ARRIVING LATE WEDNESDAY, HOWEVER GIVEN THE TRACK OF THE SURFACE LOW AND SHORT WAVE ALOFT IT ALSO LOOKS TO BE MOISTURE STARVED. FOR THURSDAY...A WEAK SURFACE HIGH IS ANTICIPATED TO MOVE ACROSS THE AREA, WHILE A FRONTAL BOUNDARY IS DRAPED FROM NEAR MAINE TO THE GREAT LAKES THEN INTO THE CENTRAL PLAINS. THE AIRMASS SHOULD BE MUCH MILDER WITH AFTERNOON HIGHS GETTING INTO THE 50S. THE OCEAN AND DELAWARE BAY ARE COLD AND IF THERE IS LIGHT ENOUGH FLOW, THEN A COOLING AFFECT CAN BE EXPECTED CLOSER TO THE COAST. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. LIFR AND IFR CONDITIONS WILL LIKELY BE PRESENT AT ALL TAF SITES INTO THE EVENING WITH ACCUMULATING SNOW. KRDG AND KABE WILL BE FIRST TO IMPROVE TO VFR BY 00Z 3/6. OTHER TAF SITES WILL FOLLOW WITH AN IMPROVEMENT TO VFR WITH KACY LAST AROUND 03Z. NORTHERLY WINDS BETWEEN 10 AND 15 KNOTS ARE EXPECTED AS WELL INTO THE EVENING, POTENTIALLY LASTING LONGER THAN CURRENT TAFS INDICATE. OVERNIGHT NORTH TO NORTHWEST WINDS SHOULD SLACKEN SLIGHTLY WITH CONTINUED VFR CONDITIONS ON FRIDAY. OUTLOOK... FRIDAY NIGHT THROUGH SUNDAY...VFR OVERALL. A WEAK SYSTEM MOVING BY LATER SATURDAY SHOULD RESULT IN MORE CLOUDS, HOWEVER ANY PRECIPITATION LOOKS TO STAY TO OUR NORTH AND WEST. MONDAY AND TUESDAY...VFR OVERALL. A WEAK COLD FRONT MOVING THROUGH MONDAY SHOULD RESULT IN MORE CLOUDS, HOWEVER IT APPEARS THAT IT MOVES THROUGH DRY. && .MARINE... WAVES ALONG THE COASTAL WATERS WILL CONTINUE TO REMAIN NEAR OR ABOVE 5 FT. IN ADDITION, WINDS ARE EXPECTED TO INCREASE SLIGHTLY THROUGH THE EVENING HOURS OUT OF THE NORTH NORTHWEST. THEREFORE THE SMALL CRAFT ADVISORY CONTINUES ON THE ATLANTIC COASTAL WATERS THROUGH THE OVERNIGHT HOURS. ON THE BAY, A FEW GUSTS ABOVE 20 KT ARE POSSIBLE, BUT CONDITIONS SHOULD GENERALLY STAY BELOW SMALL CRAFT ADVISORY CRITERIA. FOR FRIDAY, WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA. OUTLOOK... FRIDAY NIGHT AND SATURDAY...THE CONDITIONS ARE EXPECTED TO BE BELOW SMALL CRAFT ADVISORY CRITERIA, HOWEVER THE WINDS WILL INCREASE SOME FROM THE WEST-SOUTHWEST DURING SATURDAY. THERE IS A CHC FOR SOME LIGHT FREEZING SPRAY FRIDAY NIGHT AND SATURDAY MORNING. SUNDAY THROUGH TUESDAY...WE ARE ANTICIPATING SUB SMALL CRAFT ADVISORY CONDITIONS AS A WEAK FRONT MOVES THROUGH MAINLY DURING MONDAY. && .CLIMATE...
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WITH A SNOW COVER IN PLACE AND ANOTHER ARCTIC AIRMASS SETTLING INTO THE REGION AND RADIATIONAL COOLING OCCURRING WE HAVE ANOTHER CHANCE FOR MORE RECORD LOWS ACROSS THE REGION. FRIDAY 3/6 RECORD LOWS ACY 10 1888 PHL 10 1978 ILG 11 1926 ABE 7 1960 TTN 7 1872 GED 10 1978 RDG 7 1978 MPO -5 1909 THE CURRENT FORECAST CURRENTLY HAS MOST LOCATIONS BREAKING THERE RECORD LOW ON FRIDAY MORNING. THE ONE EXCEPTION WOULD BE MOUNT POCONO. SATURDAY 3/7 RECORD LOWS ACY 10 1890 PHL 9 1960 ILG 11 1960 ABE 1 1960 TTN 7 1890 GED 3 1960 RDG 10 1989 MPO -18 1911 IT APPEARS THAT READING AND ATLANTIC CITY HAVE THE BETTER CHANCE OF GETTING TO THEIR RECORD LOW SATURDAY MORNING. RECORD DAILY SNOWFALL FOR THURSDAY MARCH 5 RECORD EVENT REPORTS WILL BE SENT SHORTLY FOR KACY AND KILG AND THOSE WILL BE UPDATED AT 7 PM TONIGHT. WE MAY NEED OTHERS LATER THIS EVENING. KACY 0.3 - 1960 KILG 3.7 - 1981 KABE 7.0 - 1917 KPHL 8.8 - 1981 FWIW...WATER EQUIVALENCE OF TOTAL SNOW DEPTH IN PORTIONS OF EASTERN PA IS NOW WELL OVER 3 INCHES.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR PAZ060>062-070-071-101>106. NJ...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR NJZ007>010-012>027. DE...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR DEZ001>004. MD...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MDZ008- 012-015-019-020. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ450>455. && $$ SYNOPSIS...GORSE NEAR TERM...GAINES SHORT TERM...GAINES LONG TERM...GORSE AVIATION...GAINES/GORSE/O`HARA MARINE...GORSE/JOHNSON/O`HARA CLIMATE...DRAG 430P

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