Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 170925 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 425 AM EST WED DEC 17 2014 .SYNOPSIS... A COLD FRONT WILL CONTINUE TO MOVE OFFSHORE THIS MORNING WHILE LOW PRESSURE JUST OFFSHORE THE DELMARVA MOVES NORTHEASTWARD TODAY AND TOMORROW. HIGH PRESSURE IN THE GREAT LAKES ASSERTS CONTROL HERE ON FRIDAY. LOW PRESSURE IN GEORGIA SATURDAY MORNING IS FORECAST TO INTENSIFY AS IT MOVES NORTHEASTWARD OFF THE SOUTHERN MID ATLANTIC COAST SUNDAY INTO MONDAY. ANOTHER STORM SYSTEM MAY IMPACT THE REGION JUST BEFORE CHRISTMAS DAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DRY AND COLD AIR ADVECTION CONTINUE IN THE WAKE OF THE DOUBLE BARRELED LOW THAT IS NOW LIFTING NORTHEAST AWAY FROM THE REGION. FOR THE MOST PART, THE REGION IS DONE WITH PRECIPITATION FROM THIS SYSTEM. THE ONE EXCEPTION IS THE POCONOS AND NW NJ WHICH WILL BE CLOSER TO THE TRACK OF THE CENTER OF THE UPPER LEVEL LOW THROUGH THE DAY TODAY. HOWEVER, GIVEN THE DRIER AIR, ANY PRECIPITATION TODAY SHOULD BE LIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... BY THIS EVENING, THE SOUTHERN HALF OF THE REGION SHOULD SEE CLEARING SKIES. WIND SPEEDS, THOUGH LESS THAN DURING THE DAY, ARE EXPECTED TO BE NEAR OR ABOVE 10KT FOR MUCH OF THE NIGHT, SOMEWHAT LIMITING RADIATIONAL COOLING POTENTIAL. THEREFORE, STAYED CLOSE TO THE MAV FOR LOWS. OVER THE POCONOS, A SHALLOW NEARLY SATURATED LAYER, COMBINED WITH A SHORT WAVE TROUGH PASSAGE, COULD RESULT IN TRACE PRECIPITATION. AS FOR PRECIPITATION TYPE, CONFIDENCE IS LOW. THE NEAR SATURATED LAYER SHOULD BE SHALLOW ENOUGH THAT IT COULD BE MOSTLY FREEZING DRIZZLE. HOWEVER, MODEL SOUNDINGS SHOW THE DEPTH OF THE NEAR SATURATED LAYER RIGHT ON THE CUSP OF SUPPORTING MORE ICE CRYSTALS, SUGGESTING MORE FLURRIES. FOR NOW HAVE MENTION OF BOTH FREEZING DRIZZLE AND FLURRIES THROUGH THE EVENING HOURS ACROSS CARBON AND MONROE COUNTIES. && .LONG TERM /THURSDAY THROUGH TUESDAY/... NOT MUCH CHANGE TO THE LONGTERM FROM THE PREVIOUS 24 HOURS. LOOKS LIKE A TRANQUIL PATTERN FROM THURSDAY INTO EARLY SATURDAY BEFORE DEEPER MORE ESTABLISHED TROUGHING COMMENCES OVER THE MID-WEST. AMPLE NORTHERN AND SOUTHERN STREAM ENERGY WILL BE PASSING THROUGH FROM SUNDAY ONWARD THOUGH THINGS, FOR THE MOST PART, APPEAR TO BE DISCONNECTED WITH CONTINUED SPLIT FLOW...TUESDAY INTO WEDNESDAY THAT COULD CHANGE. THURSDAY - FRIDAY...DRYING TREND CONTINUES WITH ZONAL-ISH FLOW ALOFT FORMING BY FRIDAY AND NOT MUCH MOISTURE TO WORK WITH. INSTABILITY ALOFT CONTINUES TO LOOK ROBUST ON THURSDAY AS THE CENTER OF MID-LEVEL LOW PASSES OVERHEAD SO THERE COULD BE SOME MID-LEVEL INSTABILITY BUT WITHOUT THE MOISTURE IT IS DOUBTFUL WE WILL SEE PRECIPITATION. FRIDAY LOOKS DRY TOO. GUSTY NORTHWEST WINDS BOTH DAYS THOUGH A DECREASE IS EXPECTED LATER ON FRIDAY. SATURDAY - SUNDAY...ONE LAST DAY, OR AT LEAST HALF DAY, OF TRANQUILITY ON SATURDAY BEFORE EAST COAST STORM NEARS FROM THE SOUTH-SOUTHWEST. DEPENDING ON THE QUICKNESS AND POSITION OF THE NORTHERN STREAM ENERGY, HELPING TO DEVELOP GULF COAST SURFACE INFLECTION, DICTATES HOW FAST PRECIPITATION OVERSPREADS FROM THE SOUTH LATER ON SATURDAY. WE CONTINUE TO SEE A WEAKENING TREND IN THE OPERATIONAL GUIDANCE PACKAGES FOR THIS SYSTEM. MOST OF THE QPF EXPECTED TO FALL DURING THIS TIMEFRAME IS ASSOCIATED WITH THE NORTHERN STREAM ENERGY, AND THAT TOO LOOKS LIKE IT IS BECOMING MORE WASHED OUT. AN INVERTED TROUGH MAY THROW BACK SOME MOISTURE ACROSS THE REGION TOO. AS FOR PTYPES, THE INTERIOR ZONES HAVE THE BEST CHANCES OF SEEING SNOW WHILE I-95 EASTWARD LOOKS MOSTLY LIKE LIQUID ON SATURDAY EVENING. A MIXTURE OF RAIN/SNOW MAY OCCUR DURING THE EARLY MORNING HOURS ON SUNDAY AS THE NORTHERN TROUGH GOES SLIGHTLY NEGATIVE. AREAS FARTHER NORTH AND WEST OF PHILLY COULD SEE A LIGHT ACCUMULATION OF SNOW EARLY SUNDAY MORNING. MONDAY - TUESDAY...COULD STILL BE DEALING WITH THE LINGERING EFFECTS OF THE SYSTEM PROGGED TO MOVE BY ON SUNDAY, DEPENDING ON HOW FAST IT PULLS AWAY FROM THE REGION. STARTING TO SEE MORE NORTHERN STREAM ENERGY FUNNEL INTO THE PLAINS STATES LATER ON MONDAY AND TUESDAY. THIS WILL FORM THE NEXT SYSTEM THAT LOOKS TO IMPACT OUR REGION RIGHT BEFORE CHRISTMAS. THERE IS STILL PLENTY OF UNCERTAINTY WITH THIS SYSTEM AS WELL AND WE NEED TO SEE HOW THE PRIOR SYSTEM, ON SUNDAY/MONDAY, DISRUPTS THE MID-LEVEL FLOW, IF AT ALL, BEFORE WE HAVE ANY INKLING AS TO HOW TUESDAYS SYSTEM WILL PROGRESS. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. CONDITIONS SHOULD CONTINUE TO IMPROVE THROUGH 12Z. BY 12Z, MOST TAF SITES SHOULD BE VFR. AFTER 12Z, EXPECT SOME STRATOCUMULUS CLOUDS BETWEEN 3000 AND 5000 FT AGL. AS LONG AS THIS CLOUD LAYER STAYS ABOVE 3000 FT, CONDITIONS SHOULD REMAIN VFR THROUGH THE REST OF THE TAF PERIOD. WESTERLY WINDS GUSTING ABOVE 25KT WILL BE POSSIBLE THROUGH EARLY THIS EVENING, AND POSSIBLY CONTINUING AFTER 00Z ESPECIALLY FOR KPHL, KILG, AND KACY. OUTLOOK... THURSDAY...VFR. NORTHWEST WINDS 10-15KT WITH GUSTS 20-25KT. FRIDAY - SATURDAY...VFR. COULD SEE RAIN/SNOW SHOWERS SATURDAY AFTERNOON. SUNDAY...SUB-VFR EXPECTED WITH SCATTERED RAIN/SNOW SHOWERS. && .MARINE... WESTERLY WINDS WILL INCREASE SHORTLY AFTER SUNRISE, STAYING ABOVE SCA CRITERIA FOR MUCH OF THE DAY TODAY ON THE BAY AS WELL AS THE ATLANTIC COASTAL WATERS. WINDS ARE EXPECTED TO DIMINISH SOMEWHAT OVER THE BAY AFTER SUNSET. HOWEVER, OVER THE ATLANTIC COASTAL WATERS THE BREEZY CONDITIONS WILL CONTINUE THROUGH THE OVER NIGHT HOURS. WAVES NEAR OR ABOVE 5 FT ARE POSSIBLE ONCE THE WINDS INCREASE, ESPECIALLY ON THE ATLANTIC COASTAL WATERS. OUTLOOK... THURSDAY...SCA CONDITIONS SHOULD CONTINUE THROUGH MOST OF THE DAY BEFORE WINDS BEGIN TO DECREASE BY LATE AFTERNOON. CONFIDENCE: ABOVE AVERAGE. FRIDAY...MOSTLY SUB-ADVISORY CONDITIONS ARE EXPECTED. SOME NORTHWEST WIND GUSTS COULD STILL BE IN THE 20 PLUS KNOT RANGE, THOUGH. CONFIDENCE: ABOVE AVERAGE. SATURDAY - SUNDAY...SUB-SCA EXPECTED FOR THE MOST PART. SEAS REMAIN AROUND 3 TO 4 FEET. CONFIDENCE: AVERAGE TO SLIGHTLY BELOW AVERAGE. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THURSDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ430- 431. && $$ SYNOPSIS...HEAVENER NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...HEAVENER AVIATION...HEAVENER/JOHNSON MARINE...HEAVENER/JOHNSON

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