Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 161359 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 959 AM EDT THU APR 16 2015 .SYNOPSIS... HIGH PRESSURE WILL SHIFT FARTHER OFFSHORE TODAY, THEN WEAK LOW PRESSURE IS FORECAST TO DEVELOP NEAR THE CAROLINA COAST TONIGHT INTO FRIDAY BEFORE TRACKING NORTHEASTWARD. A COLD FRONT MOVES THROUGH OUR AREA LATER SATURDAY BEFORE STALLING TO OUR SOUTH SUNDAY. LOW PRESSURE MOVING INTO THE AREA DURING MONDAY WILL PULL THE FRONT NORTHWARD AS A WARM FRONT, THEN THE SYSTEM EXITS TO OUR EAST TUESDAY. HIGH PRESSURE SHOULD THEN BEGIN BUILDING TOWARD OUR AREA ON WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND THIS MORNING WILL SLIDE TO THE SOUTHEAST AND WILL BE LOCATED OFF THE SOUTHEAST COAST OF NEW ENGLAND BYLATE THIS AFTERNOON. A SURFACE RIDGE AXIS IS EXPECTED TO REMAIN ALONG THE LEE OF THE APPALACHIANS THROUGH THE DAY. MEANWHILE, A MID LEVEL RIDGE AXIS OVERHEAD THIS MORNING SHOULD MOVE TO OUR EAST DURING THE AFTERNOON. WE ARE EXPECTING PATCHES OF CIRRUS FROM THE WEST AND SOUTHWEST TO PASS OVERHEAD THROUGH THE DAY. THE CLOUDS ARE FORECAST TO BE SUFFICIENTLY THIN ENOUGH TO ALLOW FOR A GOOD DEAL OF SUNSHINE. A LIGHT EAST WIND THIS MORNING IS ANTICIPATED TO VEER TO THE SOUTHEAST BY EARLY AFTERNOON HOURS BEFORE SETTLING INTO THE SOUTH AT MOST LOCATIONS LATER IN THE DAY. THE WIND WILL REMAIN MORE FROM THE SOUTHEAST ON THE COASTAL PLAIN DUE TO THE EFFECTS OF THE OCEAN AND DELAWARE BAY. MAXIMUM TEMPERATURES ARE FORECAST TO BE MOSTLY NEAR 70 DEGREES, WITH HIGHS IN THE 60S IN THE ELEVATED TERRAIN NORTH AND WEST. HIGHS WILL BE IN THE UPPER 50S AND LOWER 60S ALONG THE IMMEDIATE COAST DUE TO ONSHORE FLOW FROM THE STILL COLD OCEAN.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... HIGH CLOUDS ARE FORECAST TO INCREASE AND THICKEN FOR TONIGHT. MEANWHILE, A DECK OF MID LEVEL CLOUDS SHOULD OVERSPREAD OUR REGION FROM THE WEST OVERNIGHT. LOWER CLOUDS AND RAIN SHOWERS ARE EXPECTED TO BEGIN MOVING INTO OUR WESTERN COUNTIES AROUND OR SHORTLY AFTER MIDNIGHT BASED ON THE LATEST MODEL GUIDANCE. THERE IS AN INCREASING CHANCE FOR RAIN SHOWERS LATE TONIGHT AS A MID LEVEL SHORT WAVE AND ITS ASSOCIATED SURFACE COLD FRONT BEGIN TO APPROACH FROM THE WEST AND NORTHWEST. RAINFALL AMOUNTS BY DAYBREAK ON FRIDAY ARE ANTICIPATED TO RANGE FROM ONE TO TWO TENTHS OF AN INCH IN OUR NORTHWESTERN COUNTIES TO PERHAPS A FEW HUNDREDTHS OF AN INCH IN THE SOUTHEAST. A SOUTHERLY WIND AROUND 5 TO 10 MPH IS EXPECTED FOR TONIGHT. THE SOUTHERLY SURFACE FLOW ALONG WITH THE CLOUD COVER SHOULD PREVENT TEMPERATURES FROM FALLING BELOW THE LOWER AND MIDDLE 50S AT MOST LOCATIONS. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THE SYNOPTIC SETUP IS COMPRISED OF AN INITIAL BROAD TROUGH FROM THE GREAT LAKES TO THE NORTHEAST FRIDAY, WHICH THEN AMPLIFIES SATURDAY ACROSS THE NORTHEAST. AS THIS OCCURS, A CLOSED LOW ACROSS THE CENTRAL ROCKIES DROPS EAST-SOUTHEAST EVENTUALLY EJECTING ACROSS THE PLAINS INTO SUNDAY. THIS FEATURE BUILDS RIDGING DOWNSTREAM, WHICH SHOULD SAVE MUCH OF OUR WEEKEND. THE CLOSED LOW LOOKS TO GET ABSORBED INTO A LARGE SCALE TROUGH FROM THE MIDWEST AS IT UNDERGOES AMPLIFICATION EASTWARD THROUGH EARLY NEXT WEEK. THE MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON THE SYNOPTIC PATTERN, WHICH INCREASES OUR CONFIDENCE REGARDING THE DETAILS. IT APPEARS THAT WHILE SOME WET WEATHER MOVES THROUGH FRIDAY, THE MAIN PRECIPITATION EVENT /POTENTIALLY HEAVY RAIN/ IS SCHEDULED FOR MONDAY. WE USED A MODEL BLEND FOR FRIDAY INTO SUNDAY, THEN BLENDED IN THE 00Z WPC GUIDANCE WITH CONTINUITY. SOME ADJUSTMENTS WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR FRIDAY AND SATURDAY...A COLD FRONT WILL WORK ITS WAY ACROSS THE AREA DURING FRIDAY. THERE APPEARS TO BE A SMALL WINDOW OF OPPORTUNITY FOR INCREASED MOISTURE AHEAD OF THIS FRONT, AS A NARROW CORRIDOR OF AROUND AN INCH OF PW AIR ADVECTS ACROSS THE AREA. THE BETTER CHC OF SHOWERS LOOKS TO BE FROM ABOUT INTERSTATE 95 ON NORTH AND WEST, WITH THE POTENTIAL FOR SHOWERS TO WEAKEN AS THEY TRACK FARTHER EAST. SOME OF THE MODEL FORECAST SOUNDINGS DEVELOP SOME INSTABILITY DURING FRIDAY, ALTHOUGH THE LIFT MAY NOT BE STRONG ENOUGH TO PROMOTE THUNDER. GIVEN SOME CONFLICTING SIGNALS, WE DID NOT INCLUDE THUNDER ATTM. THE ACTUAL FRONT MAY FALL APART AS IT SHIFTS ACROSS OUR AREA DURING FRIDAY. A POTENT SHORT WAVE IS THEN FORECAST TO DROP DOWN ACROSS NEW ENGLAND DURING SATURDAY WITH LOW PRESSURE AT THE SURFACE. AN ASSOCIATED COLD FRONT IS FORECAST TO MOVE THROUGH OUR AREA DURING SATURDAY THEN STALL, HOWEVER THIS FEATURE LOOKS MOISTURE STARVED ACROSS OUR REGION. AS A RESULT, WE WILL MAINTAIN A DRY SATURDAY. PLENTY OF WARMTH IS FORECAST TO ADVECT IN AHEAD OF THIS FRONT, WHICH MAY BE ENHANCED SOME BY A WEST- NORTHWEST WIND COMPONENT /DOWNSLOPING INTO THE COASTAL PLAIN/. HIGH TEMPERATURES FOR SATURDAY WERE INCREASED SOME AS A RESULT. FOR SUNDAY THROUGH TUESDAY...HIGH PRESSURE AT THE SURFACE SHOULD BUILD IN BRIEFLY FOR SUNDAY AS A FRONT IS STALLED TO OUR SOUTH. AS ENERGY EJECTS EASTWARD FROM A CLOSED LOW AND ALSO FROM THE MIDWEST, A COMPLEX SYSTEM SHOULD EVOLVE AND CONSOLIDATE EASTWARD WITH TIME. WE KEPT SUNDAY DURING THE DAY DRY DUE TO THE PRESENCE OF HIGH PRESSURE WITH MUCH OF THE LIFT HANGING BACK TO THE SOUTHWEST, THEN WAA AND MOISTURE ADVECTION BEGINS TO OVERTAKE THE AREA AT NIGHT WITH THE NORTHWARD MOVEMENT OF A WARM FRONT. THIS MAY ALLOW FOR SOME SHOWERS TO ARRIVE LATE, ALTHOUGH IT STILL LOOKS LIKE THE MORE UNSETTLED TIME FRAME IS DURING MONDAY. THE MODEL GUIDANCE APPEARS TO BE IN BETTER AGREEMENT WITH THE SYNOPTIC SETUP, THEREFORE AN AREA OF RAIN SHOULD OVERSPREAD THE REGION ON MONDAY. AN AREA OF PW AIR OF 1.0-1.5 INCHES IS FORECAST TO SURGE ACROSS THE CWA, THEREFORE THE RAIN COULD BE HEAVY AT TIMES. THE FORECAST SOUNDINGS INDICATE GENERALLY A DEEP SATURATED PROFILE WHICH TENDS TO LIMIT THE INSTABILITY. THE STEADIEST RAIN TAPERS TO SHOWERS WHICH SHOULD BE SHIFTING TO OUR NORTHEAST AND EAST MONDAY NIGHT AS A COLD FRONT ARRIVES. LOW PRESSURE AND A COLD FRONT SHOULD BE EXITING TO OUR EAST TUESDAY MORNING, WITH ANY SHOWERS ENDING. AN UPPER-LEVEL TROUGH THOUGH IS FORECAST TO LINGER FROM THE GREAT LAKES TO THE NORTHEAST, AND WITH A SURFACE TROUGH POTENTIALLY EXTENDING NEARBY SOME SHOWERS MAY PERSIST TUESDAY ESPECIALLY ACROSS THE NORTHERN ZONES. FOR WEDNESDAY...THE PRESENCE OF AN UPPER-LEVEL TROUGH FROM THE MIDWEST TO NEW ENGLAND WILL MAINTAIN SOME CYCLONIC FLOW ACROSS OUR AREA. WHILE WEAK HIGH PRESSURE BUILDS TOWARD OUR AREA FROM THE SOUTHWEST, A COLD FRONT MAY ORGANIZE ACROSS THE GREAT LAKES. WE MAY HAVE ENOUGH LIFT WITHIN THE CYCLONIC FLOW COMBINED WITH DAYTIME HEATING TO PROMOTE A FEW SHOWERS MAINLY ACROSS THE NORTH. FOR NOW, WE WENT WITH MAINLY SOME SLIGHT CHC POPS ACROSS THE NORTHWEST ZONES. && .AVIATION /14Z THURSDAY THROUGH MONDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS WITH JUST SOME HIGH CLOUDINESS ARE FORECAST FOR TODAY. AN EAST WIND AT 5 TO 10 KNOTS THIS MORNING IS EXPECTED TO VEER TO THE SOUTHEAST AND SOUTH DURING THE AFTERNOON. SPEEDS MAY REACH 10 TO 14 KNOTS FROM THE SOUTH SOUTHEAST AT KILG DUE TO THE FUNNELING EFFECT UP DELAWARE BAY. WE ARE EXPECTING CLOUDS TO INCREASE AND LOWER FOR TONIGHT WITH MAINLY VFR CONDITIONS. LIGHT RAIN SHOWERS ARE FORECAST TO SPREAD INTO OUR REGION FROM THE WEST AFTER 0400Z. CONDITIONS MAY LOWER INTO THE MVFR RANGE AROUND KRDG AND KABE AFTER 0800Z. THE WIND IS ANTICIPATED TO FAVOR THE SOUTH FOR TONIGHT AROUND 5 TO 10 KNOTS. OUTLOOK... FRIDAY...MVFR CONDITIONS AT TIMES WITH SOME SHOWERS ESPECIALLY FROM ABOUT KPHL ON NORTH AND WESTWARD, OTHERWISE VFR. SATURDAY AND SUNDAY...OVERALL VFR WITH A DRY COLD FRONTAL PASSAGE DURING SATURDAY. THE CLOUDS SHOULD INCREASE SUNDAY AND THEN LOWER TO MVFR SUNDAY NIGHT WITH THE ARRIVAL OF OUR NEXT SYSTEM. MONDAY...MVFR/IFR WITH PERIODS OF RAIN.
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&& .MARINE... HIGH PRESSURE IS FORECAST TO DROP SOUTHEASTWARD ACROSS NEW ENGLAND TODAY BEFORE MOVING OUT TO SEA TONIGHT. THE WIND DIRECTION IS EXPECTED TO VEER FROM NORTH AND NORTHEAST THIS MORNING TO SOUTHEAST AND SOUTH FOR THIS AFTERNOON AND TONIGHT. WIND SPEEDS AND WAVE HEIGHTS WILL REMAIN BELOW THE SMALL CRAFT ADVISORY CRITERIA FOR TODAY AND TONIGHT. OUTLOOK... FRIDAY AND SATURDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL CRAFT ADVISORY CRITERIA AS A COUPLE OF WEAK COLD FRONTS MOVE THROUGH. SUNDAY AND MONDAY...THE WINDS MAY BECOME MARGINAL FOR A SMALL CRAFT ADVISORY LATER SUNDAY NIGHT AND MONDAY, HOWEVER THE SEAS ARE EXPECTED TO BUILD TO AROUND 5 SUNDAY NIGHT AND MONDAY AS AN ONSHORE FLOW STRENGTHENS AHEAD OF LOW PRESSURE AND A COLD FRONT. && .FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES ARE FORECAST TO DROP INTO THE 20 TO 30 PERCENT RANGE IN MUCH OF EASTERN PENNSYLVANIA AND NEW JERSEY DURING THE AFTERNOON. MINIMUM RELATIVE HUMIDITY VALUES MAY REACH ONLY THE 30 TO 35 PERCENT RANGE IN MUCH OF DELAWARE AND NORTHEASTERN MARYLAND. THE 10-HOUR FUEL MOISTURE LEVELS APPEAR TO BE MOSTLY IN THE 7 TO 13 PERCENT RANGE IN OUR REGION EARLY THIS MORNING AND THEY SHOULD FALL MAINLY TO LESS THAN 10 PERCENT DURING THE DAY. WHILE BOTH THE LOW RELATIVE HUMIDITY VALUES AND THE DRY FINE FUELS PRESENT A FIRE WEATHER CONCERN, SUSTAINED WIND SPEEDS ARE FORECAST TO REMAIN MOSTLY LESS THAN 12 MPH WITH GUSTS NOT ANTICIPATED TO REACH MORE THAN 16 OR 18 MPH. AS A RESULT, THE POTENTIAL FOR RAPID WILDFIRE SPREAD SHOULD BE LIMITED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GORSE NEAR TERM...AMC/IOVINO SHORT TERM...IOVINO LONG TERM...GORSE AVIATION...GORSE/IOVINO MARINE...GORSE/IOVINO FIRE WEATHER...IOVINO

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