Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 282138 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 538 PM EDT THU APR 28 2016 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE TRACKS JUST TO OUR SOUTH TONIGHT INTO FRIDAY, WITH ANOTHER WEAK SYSTEM ARRIVES BY LATE FRIDAY. HIGH PRESSURE WILL THEN BUILD DOWN FROM THE NORTH SATURDAY INTO SUNDAY. LOW PRESSURE IS FORECAST TO TRACK ACROSS OUR AREA SUNDAY NIGHT AND MONDAY BEFORE SHIFTING OFFSHORE MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE MAY EXTEND INTO OUR AREA TUESDAY INTO WEDNESDAY, THEN THE NEXT COLD FRONT ARRIVES ON THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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5PM ESTF: UPDATED TEMPS/DEWS CONSIDERABLY THIS EVENING IN RESPONSE TO RAPIDLY CHANGING WET BULBING CONDITIONS IN RAIN. POPS WERE RAISED CONSIDERABLY I-78 CORRIDOR NORTHWARD TO NEAR 100 PERCENT LATE TODAY AND THIS EVENING IN RESPONSE TO RADAR RAIN WHICH BENEFICIAL AMOUNTS OF AT LEAST .1 TO .3 INCHES IN MUCH OF THIS AREA BY 03Z/29. RAIN WILL TEND TO QUIT LATE TONIGHT.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
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THE NEXT UPPER LEVEL SHORT WAVE TROUGH APPROACHES THE REGION LATE IN THE DAY TOMORROW. AS A RESULT, COULD SEE ANOTHER ROUND OF SHOWERS MOVE IN FROM THE WEST. WITH CONTINUED ONSHORE FLOW AND PERSISTENT LOW AND MID LEVEL CLOUDS, KEPT TOMORROWS HIGHS SIMILAR TO WHAT WE`VE SEEN TODAY AND YESTERDAY... GENERALLY IN THE 50S FOR MOST OF THE REGION...ABOUT 12F BELOW NORMAL.
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&& .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... THE SYNOPTIC PATTERN IS FORECAST TO BE COMPRISED OF A STRONG CLOSED LOW THAT CONTINUES TO SLOWLY EXIT THE CANADIAN MARITIMES FRIDAY NIGHT INTO SATURDAY. THIS ALLOWS THE UPPER-LEVEL FLOW TO BACK MORE WESTERLY/ZONAL OVER THE WEEKEND AS A WEAK RIDGE AXIS MOVES ACROSS. A CLOSED LOW IN THE PLAINS IS FORECAST TO OPEN UP AS IT LIFTS NORTHEAST AND EASTWARD OVER THE WEEKEND. THIS FEATURE IS SCHEDULED TO CROSS OUR AREA SUNDAY NIGHT AND MONDAY. THIS WILL DRIVE LOW PRESSURE EASTWARD, WHICH LOOKS TO TRACK ACROSS OUR AREA ON MONDAY BEFORE SHIFTING OFFSHORE. AS A RIDGE BUILDS OUT WEST, A TROUGH LOOKS TO AMPLIFY INTO THE EAST TUESDAY THROUGH THURSDAY. A COLD FRONT ASSOCIATED WITH THE LEADING EDGE OF THIS LOOKS TO APPROACH LATER WEDNESDAY THEN MOVE THROUGH OUR AREA THURSDAY. WE USED A MODEL/CONTINUITY BLEND THROUGH SUNDAY, THEN BLENDED IN THE 12Z WPC GUIDANCE THEREAFTER. SOME ADJUSTMENTS WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR FRIDAY NIGHT AND SATURDAY...AN UPPER-LEVEL FEATURE IS FORECAST TO TRANSLATE ACROSS OUR AREA TO START FRIDAY NIGHT. THIS SHOULD KEEP SOME SHOWERS GOING, HOWEVER THEY SHOULD BE ON THE WANE AS SOME RIDGING ARRIVES LATER FRIDAY NIGHT AND TO START SATURDAY. THE UPPER- LEVEL FLOW THEN BACKS SOME AS A TROUGH TAKES ON SOME AMPLIFICATION IN THE GREAT LAKES LATE SATURDAY. THIS WILL ALLOW FOR WAA AND INCREASING ISENTROPIC LIFT TO START OVERSPREADING OUR AREA SATURDAY NIGHT. THIS MAY RESULT IN SOME RAIN ARRIVING LATER SATURDAY NIGHT, AND THE MODEL GUIDANCE OVERALL APPEARS TO BE FASTER IN BRINGING IN THE PRECIPITATION. AS A RESULT, WE SPED UP THE POP INCREASE SATURDAY NIGHT. DUE TO SOME BRIEF DRYING SATURDAY, TEMPERATURES SHOULD MODIFY SOME DURING THE DAY. FOR SUNDAY AND MONDAY...AS AN UPPER-LEVEL TROUGH AMPLIFIES EASTWARD, SURFACE LOW PRESSURE IS FORECAST TO ARRIVE IN OUR AREA LATER SUNDAY AND MONDAY. HOWEVER, THERE APPEARS TO BE PLENTY OF WAA AND ISENTROPIC INDUCED LIFT AS A WARM FRONT EDGES CLOSER DURING SUNDAY. GIVEN THE FLOW BACKING TO THE SOUTHWEST, PRECIPITATION MAY QUICKLY MOVE ACROSS THE AREA. LINGERING SURFACE HIGH PRESSURE TO OUR NORTHEAST THOUGH WILL RESULT IN SOME SORT OF A WEDGE INITIALLY AND COULD ALLOW ENOUGH DRY LOW-LEVEL AIR TO HOLD ON A LITTLE LONGER. OVERALL THOUGH, MOISTURE INCREASING FROM THE SOUTHWEST SHOULD OVERTAKE THIS. AS A RESULT, THIS TIME FRAME LOOKS RATHER UNSETTLED WITH RAIN AT TIMES. THE STEADIER RAIN MAY THEN BECOME SHOWERY ON MONDAY AS THE BETTER OVERRUNNING STARTS TO SHIFT TO OUR NORTHEAST. SOME GUIDANCE SUGGESTS LESS PRECIPITATION ON MONDAY WHICH WOULD OCCUR IF THE SURFACE LOW IS FASTER. IT APPEARS THE WARM SECTOR MAY EDGE INTO OUR SOUTHERN AREAS SUNDAY INTO MONDAY. WHILE SOME THUNDER CANNOT BE RULED OUT WITHIN THE WARM SECTOR /PERHAPS SOME ELEVATED INSTABILITY NORTH OF THE WARM FRONT/, IT IS LESS CERTAIN IF IT WOULD BE ENOUGH FOR THUNDER. AS A RESULT, NO THUNDER WAS ADDED ATTM. THE SHOWERS SHOULD END MONDAY NIGHT AS THE SYSTEM SHIFTS OFFSHORE AND THE LOW-LEVEL FLOW TURNS MORE FROM THE NORTH AND NORTHWEST. FOR TUESDAY THROUGH THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO AMPLIFY INTO THE EAST TUESDAY AND WEDNESDAY. AS THIS STARTS TO OCCUR, THE MONDAY FRONTAL BOUNDARY MAY HAVE A WAVE OF LOW PRESSURE RUNNING UP THE FRONT. THIS COULD AT LEAST BRUSH OUR EASTERN AND SOUTHERN ZONES TUESDAY, HOWEVER THERE IS LOW CONFIDENCE WITH THIS. AS THE AFOREMENTIONED TROUGH AMPLIFIES MORE INTO THURSDAY, A COLD FRONT LOOKS TO ARRIVE. THERE SHOULD BE ENOUGH HEATING AND WAA TO ALLOW TEMPERATURES TO MODIFY SOME PRIOR TO THE ARRIVAL OF THE COLD FRONT. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,KMIV, KACY AND SURROUNDING AREAS. TONIGHT...CONDITIONS LOWERING TO MVFR OR IFR IN ST/FOG AND PERIODS OF SHOWERY RAINS...MOST OF THE RAIN NORTH OF PHL. AREAS OF DRIZZLE POSSIBLE LATER ON TONIGHT. LIGHT NE WIND. MODERATE TO HIGH CONFIDENCE. FRIDAY...CONDITIONS PROBABLY IMPROVING TO MVFR OR VFR CIGS DURING MIDDAY. MODERATE CONFIDENCE. NE WIND WITH A FEW GUSTS 15-20 KT POSSIBLE I-95 EAST. OUTLOOK... FRIDAY NIGHT...MVFR CONDITIONS IN THE EVENING WITH SOME SHOWERS SHOULD THEN IMPROVE TO VFR. NORTHEAST WINDS 10 KNOTS OR LESS. SATURDAY...VFR DURING THE DAY, THEN LOWER TO MVFR AT NIGHT AS SOME RAIN APPROACHES. EAST-SOUTHEAST WINDS AROUND 10 KNOTS OR LESS. SUNDAY AND MONDAY...MVFR TO POTENTIALLY IFR CONDITIONS ALONG WITH RAIN AT TIMES. THE CONDITIONS MAY START IMPROVING MONDAY NIGHT. TUESDAY...VFR OVERALL.
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&& .MARINE... WINDS INCREASED MID DAY TODAY ALONG THE LOWER DELAWARE BAY AND ADJACENT COASTAL WATERS. OCCASIONAL GUSTS NEAR OR ABOVE 25 KT WILL CONTINUE THROUGH AT LEAST LATE THIS EVENING. NEAR MIDNIGHT THE EXPECT CONDITIONS TO BE BELOW SCA CRITERIA ON THE DELAWARE BAY. ON THE COASTAL WATERS, SEAS WILL SUBSEQUENTLY INCREASE, AND SHOULD BE ABOVE 5 FEET BY LATE TONIGHT CONTINUING THROUGH THE DAY TOMORROW. OUTLOOK... FRIDAY NIGHT...NORTHEASTERLY WIND GUSTS OF 20 TO 25 KNOTS ON THE OCEAN ZONES ALONG WITH SEAS TO AROUND 5 FEET. THESE SHOULD SUBSIDE DURING THE NIGHT AND THEREFORE THE SMALL CRAFT ADVISORY WAS KEPT UNTIL 06Z SATURDAY. SATURDAY AND SUNDAY...THE WINDS AND SEAS SHOULD BE BELOW ADVISORY CRITERIA DESPITE INCOMING LOW PRESSURE LATE SUNDAY. MONDAY AND TUESDAY...NORTHEAST WINDS MONDAY SHOULD SHIFT TO NORTHWEST AT NIGHT INTO TUESDAY BEFORE SHIFTING BACK EASTERLY. IT APPEARS THAT THE WINDS REMAIN UNDER 25 KNOTS, HOWEVER SEAS MAY BUILD TO 5 FEET FOR A TIME ON THE OCEAN ZONES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR ANZ452>455. SMALL CRAFT ADVISORY FROM 1 AM FRIDAY TO 2 AM EDT SATURDAY FOR ANZ450-451. SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ430-431. && $$ SYNOPSIS...GORSE NEAR TERM...DRAG/JOHNSON 538 SHORT TERM...JOHNSON LONG TERM...GORSE AVIATION...DRAG/GORSE/JOHNSON 538 MARINE...GORSE/JOHNSON

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