Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 152329 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 729 PM EDT WED APR 15 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD ACROSS THE NORTHEAST TONIGHT INTO THURSDAY. THE HIGH WILL BUILD OFFSHORE AND TO SEA THURSDAY NIGHT INTO FRIDAY. A COUPLE OF LOW PRESSURE SYSTEMS ARE FORECAST TO CROSS SOUTHERN CANADA FRIDAY AND SATURDAY. THIS FIRST IS EXPECTED TO PULL A COLD FRONT ACROSS THE AREA FRIDAY, THEN THE SECOND IS EXPECTED TO PUSH A COLD FRONT ACROSS THE AREA SATURDAY. HIGH PRESSURE MAY BRIEFLY AFFECT THE NORTHEAST SATURDAY NIGHT INTO EARLY SUNDAY, BEFORE A COMPLEX WEATHER SYSTEM MOVES INTO THE GREAT LAKES AND NORTHEAST EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... HIGH PRESSURE LOCATED IN SOUTHEAST CANADA WILL CONTINUE TO RESULT IN MOSTLY CLEAR SKIES TONIGHT. WINDS WILL DECREASE THIS EVENING WITH THE LOSS OF DAYTIME HEATING AND MIXING. THE AIRMASS ASSOCIATED WITH THE HIGH PRESSURE IS NOT EXTREMELY CHILLY AND WILL LIMIT HOW FALL TEMPERATURES CAN DROP TONIGHT. THE COLDEST READINGS WILL BE ACROSS NORTHERN NJ AND THE POCONOS IN THE MID 30`S WHERE THE FORECAST DOES ALLOW FOR THE MOST EFFICIENT RADIATIONAL COOLING AND IS COOLER THAN MOST STAT GUIDANCE. THE GROWING SEASON HAS NOT YET STARTED AT THOSE LOCATIONS. RURAL AREAS IN EASTERN PA AND THE PINE BARRENS IN SOUTHEAST NJ MAY ALSO SEE LOWS IN THE UPPER 30`S, JUST A FEW DEGREES TO WARM FOR FROST CONCERNS ATTM. LOWS WILL BE IN THE LOW TO MID 40`S OUTSIDE OF THESE AREAS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... HIGH PRESSURE OFFSHORE OF ATLANTIC CANADA WILL ALLOW FOR A CHANGE THE WIND DIRECTION FROM NORTHEASTERLY TO SOUTHEASTERLY BY THE AFTERNOON THURSDAY. OVERALL, IT LOOKS LIKE ANOTHER MOSTLY SUNNY DAY WITH AN INCREASE IN MID AND HIGH LEVEL CLOUDS LATE AHEAD OF THE NEXT SYSTEM. WINDS SHOULD STAY UNDER 10-15 MPH FOR THE MOST PART WITH SOME GUSTS AROUND 15 MPH. THE CHANGE IN WIND DIRECTION WILL ALLOW FOR HIGHER DEWPOINTS THAN WHAT WE SAW TODAY BUT THE MOISTURE ADVECTION IS LIKELY TO FAST ON THE MET AND MAV GUIDANCE SETS. ABUNDANT SUNSHINE WILL ALLOW FOR EFFICIENT WARMING WELL INTO THE 60`S FOR MOST, SUPPORTED BY 925 MB TEMPS AROUND 8C. MODELED TWO METER TEMPERATURES LOOK TO COOL HERE. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... TWO LOW PRESSURE SYSTEMS ARE FORECAST TO BE SLIDING ACROSS SOUTHERN CANADA FRIDAY AND AGAIN SATURDAY. A FRONT ASSOCIATED WITH THE FIRST LOW PRESSURE SYSTEM IS EXPECTED TO CROSS THE AREA DURING THE DAY FRIDAY. THERE COULD BE SOME PRECIPITATION START OVERNIGHT THURSDAY JUST AHEAD OF THE FRONTAL BOUNDARY AS MOISTURE INCREASES AND LIFT IS ENHANCED WITH THE PASSAGE OF A SHORT WAVE/VORTICITY IMPULSE. MODELS KEEP PRECIPITATION CHANCES ACROSS THE AREA THROUGH THE FRIDAY AS THE FRONT PASSES ACROSS THE AREA. THE SECOND OF THE LOWS IS FORECAST TO BRING A COLD FRONT ACROSS THE AREA SATURDAY. MODEL GUIDANCE IS INDICATING THIS FRONTAL PASSAGE WILL BE DRY, SO WE WILL KEEP THE FORECAST DRY SATURDAY. BRIEF HIGH PRESSURE MAY BRIEFLY BUILD ACROSS THE NORTHEAST SATURDAY NIGHT INTO THE EARLY PART OF SUNDAY AS THE FRONTAL BOUNDARY STALLS TO OUR SOUTH. THIS SHOULD KEEP THE WEATHER DRY SATURDAY NIGHT INTO EARLY SUNDAY. HOWEVER, THIS DRY WEATHER IS NOT EXPECTED TO LAST LONG AS A COMPLEX WEATHER SYSTEM IS BEING DEPICTED BY THE GFS AND ECMWF FOR EARLY NEXT WEEK. THE GUIDANCE IS SHOWING SEVERAL LOW PRESSURE SYSTEMS TO OUR WEST, ONE ACROSS SOUTHERN CANADA, ONE ACROSS THE DEEP SOUTH, AND ONE ACROSS THE CENTRAL PLAINS, EVENTUALLY MOVING INTO THE GREAT LAKES AREA BY SUNDAY NIGHT/EARLY MONDAY AND MERGING INTO ONE LARGE LOW PRESSURE. THE FRONTAL BOUNDARY TO OUR SOUTH IS EXPECTED TO LIFT BACK NORTHWARD ACROSS OUR AREA MONDAY INTO MONDAY NIGHT, WHILE ANOTHER COASTAL LOW MAY DEVELOP ALONG THE FRONT AS IT LIFTS ACROSS THE AREA. THIS IS EXPECTED TO LEAD TO AN EXTENDED PERIOD OF PRECIPITATION STARTING AS EARLY AS THE LATTER PART OF SUNDAY AND CONTINUING INTO MONDAY NIGHT. THE FRONT AND COASTAL LOW WILL SLOWLY LIFT TO OUR NORTH THROUGH TUESDAY, SO SHOWERS COULD LINGER INTO THE DAY TUESDAY. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. HIGH CIRRUS CLOUDS ARE POSSIBLE THROUGH TONIGHT WITH A FEW MID LEVEL CLOUDS ON THURSDAY. NORTHERLY WIND GUSTS WILL DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME HEATING. WINDS ARE EXPECTED TO GRADUALLY SHIFT TO EAST NORTHEASTERLY OVERNIGHT TONIGHT UNDER 10 KNOTS THEN TO EASTERLY IN THE MORNING FROM 8-10 KNOTS. THE WINDS WILL THEN SHIFT SOUTHEASTERLY BY THURSDAY AFTERNOON. OUTLOOK... THURSDAY NIGHT-FRIDAY...MVFR CONDITIONS POSSIBLE WITH SCATTERED SHOWERS. FRIDAY NIGHT-SUNDAY..GENERAL VFR CONDITIONS. SUNDAY NIGHT-MONDAY...CONDITIONS LOWERING TO MVFR OR IFR WITH RAIN EXPECTED. && .MARINE... SEAS WILL REMAIN AROUND THREE FEET THROUGH THURSDAY WITH MAXIMUM WIND GUSTS AROUND 20 KNOTS EARLY THIS EVENING THEN AGAIN THURSDAY AFTERNOON. THE WINDS WILL SHIFT FROM NORTHERLY TONIGHT TO EASTERLY BY THURSDAY MORNING THEN SOUTHEASTERLY BY THE AFTERNOON. NO SCA HEADLINE. OUTLOOK... THURSDAY NIGHT-SATURDAY NIGHT...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED. FRONTAL PASSAGES EXPECTED FRIDAY AND SATURDAY. SUNDAY-MONDAY...WINDS MAY APPROACH SMALL CRAFT ADVISORY LEVELS SUNDAY NIGHT INTO MONDAY, BUT SEAS ARE EXPECTED TO BUILD TO 5 FEET OR MORE OVERNIGHT SUNDAY AND CONTINUE INTO MONDAY. && .FIRE WEATHER... FOR THURSDAY, THE RELATIVE HUMIDITY VALUES ARE FORECAST TO DROP TO 25-35 PERCENT IN THE AFTERNOON MAINLY FOR NEW JERSEY /AWAY FROM THE COAST/ AND EASTERN PENNSYLVANIA. TOP WIND GUSTS LOOK TO BE AROUND OR JUST ABOVE 15 MPH IN THE AFTERNOON. THESE VALUES ARE SHORT OF MEETING RED FLAG CRITERIA BUT WITH DRY FINE FUELS AN ELEVATED FIRE RISK STILL MAY STILL BE PRESENTED && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...ROBERTSON NEAR TERM...GAINES SHORT TERM...GAINES LONG TERM...ROBERTSON AVIATION...GAINES/ROBERTSON MARINE...GAINES/ROBERTSON FIRE WEATHER...

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