Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 032016 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 416 PM EDT WED JUN 3 2015 .SYNOPSIS... OUR REGION WILL BE SANDWICHED BETWEEN HIGH PRESSURE ACROSS NORTHERN NEW ENGLAND TONIGHT AND A STATIONARY FRONTAL BOUNDARY TO OUR SOUTHEAST. THESE FEATURES WILL MOVE LITTLE UNTIL TOMORROW NIGHT WHEN A WAVE OF LOW PRESSURE MOVES OFFSHORE ALONG THE FRONT. THIS WILL BE FOLLOWED BY A COLD FRONTAL BOUNDARY MOVING SOUTHEAST INTO THE REGION ON SATURDAY. THIS FRONT WILL THEN MOVE NORTHWARD AS A WARM FRONT BY MONDAY AHEAD OF THE NEXT STORM SYSTEM. ANOTHER COLD FRONT WILL MOVE EASTWARD THROUGH THE REGION BY THE MIDDLE OF NEXT WEEK WITH HIGH PRESSURE BUILDING SOUTHEASTWARD BEHIND THE FRONT. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A STATIONARY FRONTAL BOUNDARY/INVERTED SURFACE TROUGH THAT WAS SITUATED ALONG THE CAROLINA COAST THIS AFTERNOON EXTENDS NORTHEASTWARD WELL OFF THE DELMARVA COAST. MEANWHILE, HIGH PRESSURE WAS CENTERED ALONG THE NEW ENGLAND COAST. ALTHOUGH THE CENTER OF THE HIGH WILL MOVE OFFSHORE TONIGHT, IT WILL CONTINUE TO NOSE SOUTHWESTWARD WITH THE RIDGE AXIS BISECTING THE CWA. LOOKING ALOFT, A CUTOFF LOW WAS LOCATED OVER THE SOUTHERN APPALACHIANS. THIS FEATURE IS EXPECTED TO MAKE LITTLE DOWNSTREAM PROGRESSION TONIGHT. A WEAK MID-LEVEL SHORTWAVE TROUGH ON THE NORTHEASTERN SIDE OF THE LOW IS FORECAST TO LIFT NORTHWARD FROM JUST EAST OF THE OUTER BANKS THIS AFTERNOON TOWARD THE DELMARVA TONIGHT. THE ABOVE MENTIONED PATTERN WILL CONTINUE TO YIELD AN EAST- NORTHEAST FLOW ACROSS THE REGION. THE TRAJECTORY FROM THE ATLANTIC WILL BE RESPONSIBLE FOR YET ANOTHER COOL AND CLOUDY PERIOD. HOWEVER, CLOUDS HAVE ERODED ALMOST COMPLETELY ACROSS NORTHEAST PA AND NORTHERN NJ THIS AFTERNOON AS A RESULT OF DRIER AIR ADVECTING IN FROM THE NEW ENGLAND HIGH PRESSURE SYSTEM. EXPECT CLOUDY CONDITIONS TO CONTINUE ACROSS THE REST OF THE AREA INTO TONIGHT AND CLOUDS WILL INCREASE IN THESE NORTHERN AREAS OVERNIGHT. SHOWER ACTIVITY TODAY HAS BEEN CONFINED TO SOUTHERN DELAWARE AND CAPE MAY, NJ. EXPECT COVERAGE OF SHOWERS TO INCREASE GRADUALLY OVER THE DELMARVA LATE THIS EVENING AND ESPECIALLY OVERNIGHT AS THE SHORTWAVE TROUGH MOVES NORTHWARD. MOST OF THE 12Z MODEL GUIDANCE HAD BACKED OFF CONSIDERABLY ON NORTHERN ADVANCEMENT OF THE PRECIP AND ALSO COVERAGE (EXCEPT THE NAM). KEPT ANY MENTION OF SHOWERS OUT OF THE FORECAST NORTH OF A LINE FROM BLM-TTN-ABE-MPO. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... HIGH PRESSURE WILL MOVE INTO THE GULF OF MAINE WHILE THE FRONTAL BOUNDARY REMAINS STALLED TO OUR SOUTH AND EAST. THE CUTOFF LOW IS FINALLY EXPECTED TO BECOME AN OPEN WAVE AND MOVE EASTWARD INTO THE CAROLINAS. A MID-LEVEL SHORTWAVE TROUGH AND LOW-LEVEL THETA-E RIDGE WILL LIFT NORTHWARD THRU THE AREA TOMORROW. THERE IS STILL SOME UNCERTAINTY REGARDING HOW FAR NORTH THE SHOWERS WILL MAKE IT AS PRECIP MOVES INTO RESIDUAL DRY AIR NOSING IN FROM THE HIGH TO OUR NORTHEAST. POPS DECREASE FROM SOUTH TO NORTH ACCORDINGLY. NORTHWEST NJ HAS THE BEST CHANCE TO STAY DRY TOMORROW. A PERSISTENT ONSHORE FLOW AND CLOUDY SKIES WILL YIELD ANOTHER COOLER THAN NORMAL DAY FOR EARLY JUNE STANDARDS. FORECAST HIGHS ARE IN THE 60S. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... THURSDAY NIGHT THROUGH FRIDAY NIGHT: A LOW PRESSURE SYSTEM IS LIKELY TO ORGANIZE ALONG A FRONTAL BOUNDARY OFFSHORE. THIS WILL LEAD TO ANOTHER CLOUDY PERIOD WITH INCREASED RAIN CHANCES FOCUSED ACROSS COASTAL NJ AND THE DELMARVA THURSDAY NIGHT. LOW TEMPERATURES MAY BE KEPT UP A BIT AT NIGHT AND LOWER DURING THE DAY FRIDAY DUE TO CLOUDS AND RAIN CHANCES. THE MORE AGGRESSIVE THE CLOUDS AND LIGHT RAIN SHOWERS ARE MEANS MORE IN WAY OF TEMPERATURE SPREAD ACROSS THE REGION DUE TO CLOUDS/RAIN. BROUGHT HIGH TEMPERATURES DOWN SEVERAL DEGREES ON FRIDAY FOR THIS PROSPECT, BUT NOT AS COOL AS THE WETTER 12Z ECMWF RUN. LOWS IN THE 50`S AND HIGHS IN THE LOW 70`S ON AVERAGE. THE HIGHEST QPF SHOULD BE UNDER 1/4TH OF AN INCH. SATURDAY THROUGH SUNDAY NIGHT: A WEAK COLD FRONT WILL MOVE THROUGH THE REGION ON SATURDAY. AS A RESULT, ISOLATED SHOWERS AND STORMS ARE POSSIBLE ALONG IT BUT MOISTURE LOOKS LIMITED ATTM. FEATURING JUST A LOW RAIN CHANCE. PRECIPITATION CHANCES SHOULD SHIFT SOUTH OF THE REGION ON SUNDAY ALONG THE FRONTAL BOUNDARY TO OUR SOUTHWEST. 925 MB TEMPERATURES RISE TO AROUND 15C WHICH SHOULD ALLOW US TO REACH AROUND OR JUST OVER 80 WITH MORE IN THE WAY OF SUNSHINE. LARGER TEMPERATURE SPREAD AT NIGHT WITH LOWS IN THE 50`S TO LOW 60`S. MONDAY THROUGH TUESDAY: POTENTIALLY THE MOST ACTIVE DAY OF THE PERIOD. TIMING WILL BE MORE SIGNIFICANT THAN USUAL AS WELL. AFTER A WARM FRONTAL PASSAGE, HIGHER AMOUNTS OF MOISTURE AND INSTABILITY SHOULD ADVECT NORTHWARD INTO THE REGION AHEAD OF THE NEXT COLD FRONTAL BOUNDARY. BOTH MODELS HAVE SLOWED THE COLD FRONT A BIT WHICH WOULD ALLOW FOR SOME DESTABILIZATION OF THE ATMOSPHERE MONDAY AFTERNOON AND EVENING, PERHAPS INTO TUESDAY. THE DEGREE OF INSTABILITY WILL DETERMINE TO WHAT DEGREE AND STRENGTH OF ANY THUNDERSTORMS THAT OCCUR AHEAD OF THE COLD FRONTAL BOUNDARY. BULK SHEAR LOOKS SUFFICIENT FOR STRONG TO SEVERE STORMS SHOULD THE INSTABILITY MATERIALIZE. HIGH PW`S MAY LEAD TO SOME LOCALLY HEAVY DOWNPOURS AS WELL. WITH SOME TIMING UNCERTAINTY WILL GO WITH A HIGHER CHANCE POPS BUT NOT LIKELY FOR POPS WITH SHOWERS AND THUNDERSTORMS IN THIS PERIOD. 925 MB TEMPERATURES WILL INCREASE SLIGHTLY WITH A WARM SOUTHERLY FLOW IN PLACE AS WELL. OUTSIDE ANY STORMS HIGHS SHOULD RISE INTO THE 80`S WITH MUGGIER LOWS IN THE 60`S. TUESDAY NIGHT AND WEDNESDAY: HIGH PRESSURE SHOULD BUILD BACK INTO THE REGION THROUGHOUT THE REMAINDER OF THIS PERIOD WITH MOSTLY SUNNY CONDITIONS AND LOWER HUMIDITY. WPC AND ENSEMBLE GUIDANCE WAS MAINLY USED IN THIS PERIOD. NOT MUCH IN THE WAY OF COOLER AIR BEHIND THE FRONT. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. PREDOMINATELY VFR THRU THIS EVENING (ALTHOUGH CIGS MAY BRIEFLY LOWER TO 3 KFT AND PRODUCE MVFR CONDITIONS) AT SOME OF THE TAF SITES. EXPECT CIGS TO LOWER TO MVFR OVERNIGHT FROM SOUTH TO NORTH. SHRA EXPECTED TO EXPAND NORTHWARD FROM THE DELMARVA LATE THIS EVE. CONFIDENCE ONLY HIGH ENOUGH TO MENTION SHRA IN THE SOUTHERN TERMINALS (ILG, MIV, ACY). E-NE WINDS 5-15 KT THRU TONIGHT. 18Z TAFS WERE CONSERVATIVE WITH THE LOW CLOUDS AND DID NOT FORECAST IFR CIGS LIKE THE LAMP/NAM GUIDANCE WAS SHOWING. MVFR CIGS TO START THE DAY SHOULD IMPROVE TO VFR BY LATE IN THE MORNING. EAST WINDS 10-15 KT. OUTLOOK... THURSDAY NIGHT AND FRIDAY: MVFR TO IFR RESTRICTIONS POSSIBLE WITH SCATTERED SHOWERS AND DRIZZLE. HIGHEST CHANCES FROM PHL EAST. NORTHEAST WIND GUSTS AROUND 10 KNOTS. FRIDAY NIGHT THROUGH SUNDAY NIGHT: MAINLY VFR WITH WINDS UNDER 10 KNOTS. MONDAY: SOME RESTRICTIONS POSSIBLE TO MVFR OR IFR IN SCATTERED AFTERNOON THUNDERSTORMS, HIGHEST CHANCES FOR RDG AND ABE. SOUTH WINDS AROUND 15 KNOTS WITH GUSTS UP TO 25 KNOTS IN THE AFTERNOON && .MARINE... SCA CONTINUES FOR THE COASTAL WATERS TONIGHT AND THURSDAY. WINDS WILL BE 15-20 KT WITH OCCASIONAL GUSTS TO 25 KT, WHICH IS RATHER MARGINAL. HOWEVER, SEAS WILL REMAIN 4-7 FT DURING THIS TIME. THE SCA FOR THE DE BAY CONTINUES INTO TONIGHT. WE MAY BE ABLE TO CANCEL IT EARLY AS WINDS LOOK TO DIMINISH A BIT OVERNIGHT. OUTLOOK... THURSDAY NIGHT THROUGH FRIDAY: CONTINUING WITH THE SCA ON THE COASTAL ZONES THROUGH 10Z FRIDAY AS WAVEWATCH CONTINUES TO MODEL SEAS AT OR OVER FIVE FEET TILL THIS POINT. NORTHEASTERLY WIND GUSTS AROUND 20 KNOTS ARE ALSO POSSIBLE THROUGH FRIDAY. SEAS FRIDAY ARE CURRENTLY MODELED ABOUT FOUR FEET, WAVEWATCH HAS HAD A LOW BIAS DUE TO THE ONSHORE FLOW THE LAST FEW DAYS. SO THE SEAS MAY BE HIGHER AND CLOSER TO SCA CRITERIA. SINCE CONFIDENCE WAS NOT HIGH, THE SCA WAS NOT EXTENDED FURTHER. FRIDAY NIGHT THROUGH SUNDAY NIGHT: SEAS AND GUSTS SHOULD STAY UNDER SCA CRITERIA WITH WINDS GRADUALLY CHANGING TO MORE SOUTHERLY BY MONDAY. MONDAY: SEAS BUILDING TO OR GREATER THAN SCA CRITERIA. SOUTHERLY WIND GUSTS FROM 25-30 KNOTS AS WELL MAINLY IN THE AFTERNOON AND NIGHT. THUNDERSTORMS POSSIBLE AS WELL MONDAY AFTERNOON AND NIGHT. && .RIP CURRENTS... A NORTHEAST WIND IS EXPECTED FOR TODAY ALONG THE COASTS OF NEW JERSEY AND DELAWARE AT SUSTAINED SPEEDS OF 10 TO 20 MPH. ALSO, THE TIDAL RANGE REMAINS LARGE DUE TO THE FULL MOON. AS A RESULT, WE ARE FORECASTING A MODERATE RISK OF RIP CURRENTS FOR TODAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ430-431. && $$ SYNOPSIS...GAINES NEAR TERM...KLEIN SHORT TERM...KLEIN LONG TERM...GAINES/MIKELL AVIATION...GAINES/KLEIN MARINE...GAINES/KLEIN RIP CURRENTS...STAFF

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