Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 282307 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 707 PM EDT THU APR 28 2016 .SYNOPSIS... LOW PRESSURE IN NORTH CAROLINA GRADUALLY SHIFTS OUT TO SEA OFF THE MID ATLANTIC COAST LATER FRIDAY OR FRIDAY NIGHT. 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. THE NEXT COLD FRONT ARRIVES ON THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 630PM ESTF: FURTHER COOLING AND WET BULBING THE TEMPS/DEWS THIS EVENING AND HOPEFULLY HAVE IT STABLE THE REMAINDER OF THE NIGHT. RAISED POPS TO NEAR 100 PCT THIS EVENING 00-01Z I78-I80 AS IT LOOKS LIKE THERE IS ENOUGH MODELING AND RADAR REALITY TO JUSTIFY MEASURABLE INTERMITTENT SHOWERY RAINS THROUGH THIS EVENING. ITS POSSIBLE I`LL HAVE TO ADD MORE POP DOWN TO PHILLY AND MT HOLLY THIS EVENING. CONVECTION MOVING EWD FROM VA SHOULD DIMINISH TO SCT SHOWERS CROSSING THE DELMARVA TONIGHT. RAIN WILL TEND TO QUIT LATE TONIGHT THOUGH THERE MAY BE SOME AREAS OF DRIZZLE AND LESS THAN 2 MI FOG. AMOUNTS THROUGH 630 PM: 0.31 AROUND READING PA SO FAR, 0.26 POTTSTOWN AND WIDESPREAD .1 TO .2 I-78 REGION AS OF 630 PM. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... THE NEXT UPPER LEVEL SHORT WAVE TROUGH CROSSES ESEWD ALONG I-80 LATE TOMORROW AND IS SOMEWHAT IMPRESSIVE (TIGHT 500MB VORT) DESPITE MINOR 30 METER 12 HR 500 MB HFC. HAVE RAISED POPS 30-40 PCT N OF I-78 FRIDAY AFTERNOON. 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. && .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 /23Z THURSDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,KMIV, KACY AND SURROUNDING AREAS. REMAINDER OF 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. HIGH CONFIDENCE. FRIDAY...CONDITIONS PROBABLY IMPROVING TO MVFR OR VFR CIGS DURING MIDDAY. MODERATE CONFIDENCE BUT MAY LOWER IN RAIN DURING THE AFTERNOON, ESPECIALLY KRDG/KABE AND KTTN. NE WIND WITH A FEW GUSTS 15-20 KT POSSIBLE I-95 EASTWARD. 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. && .MARINE...
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705PM: DISCONTINUED SCA UPPER DE BAY. LOOKS LIKE MOST GUSTS TONIGHT THERE AOB 22KT. ELSEWHERE..EXPECTING INCREASING WIND AND SEA TONIGHT INTO FRIDAY. 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.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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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 10 AM EDT FRIDAY FOR ANZ431.
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&& $$ SYNOPSIS...DRAG/GORSE NEAR TERM...DRAG SHORT TERM...DRAG/JOHNSON LONG TERM...GORSE AVIATION...DRAG/GORSE MARINE...DRAG/GORSE 708P

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