Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 220756 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 356 AM EDT FRI AUG 22 2014 .SYNOPSIS...
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A HIGH CENTERED OVER EASTERN CANADA NOW, WILL SLOWLY BUILD SOUTH APPROACHING THE REGION OVER THE WEEKEND. THIS WILL REMAIN THE DOMINANT WEATHER FEATURE FOR OUR REGION THROUGH EARLY NEXT WEEK. A COLD FRONT WILL APPROACH THE AREA LATE NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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AN AREA OF SHOWERS AND WITH ISOLATED THUNDERSHOWERS ARE PUSHING SOUTHWARD ACROSS THE AREA THIS MORNING. THEY HAVE BEEN REDEVELOPING ALONG A THETA-E AND INSTABILITY DIFFERENTIAL LINE AS THE SHORT WAVE/VORT MAX ALOFT MOVES INTO THE AREA. THE SHORT WAVE IS EXPECTED TO PUSH ACROSS THE AREA AROUND OR SHORTLY AFTER DAYBREAK, SO THIS SHOWER/THUNDER SHOWER ACTIVITY WILL CONTINUE THROUGH DAYBREAK, BUT BEGIN TO DIMINISH AND MOVE OFFSHORE BY THAT TIME. ONCE THIS ACTIVITY WANES, WE SHOULD GET A BREAK IN THE MORE WIDESPREAD SHOWERS FOR MUCH OF THE MORNING INTO THE EARLY AFTERNOON. HOWEVER, WE EXPECT MORE SHOWERS TO DEVELOP AND MOVE INTO THE AREA LATER TODAY AS ANOTHER SHORT WAVE/VORTICITY IMPULSE MOVES INTO THE AREA IN THE NORTHWEST FLOW ALOFT. THE BEST CHANCE FOR ANY PRECIPITATION WILL BE FOR THE WESTERN TWO-THIRDS OF THE AREA, WHILE THE COAST MAY REMAIN DRY LATER TODAY. THERE REMAINS SOME WEAK INSTABILITY, SO THERE WILL REMAIN THE CHANCE FOR ISOLATED/SCATTERED THUNDERSTORMS AS WELL. AS WITH YESTERDAY, WITH THE LACK OF A STRONG WIND FIELD ALOFT AND MINIMAL SHEAR, WE DO NOT EXPECT ANY SEVERE WEATHER. IF ANY THUNDERSTORMS DO DEVELOP, THEY COULD PRODUCE GUSTY WINDS, IN ADDITION TO HEAVY RAIN AS PW VALUES REMAIN 1.5-1.75 INCHES. ALSO CANNOT RULE OUT THE POSSIBILITY FOR SMALL HAIL IF THERE ARE ANY THUNDERSTORMS AS WELL. FOR HIGHS, USED A BLEND OF MAV/MET MOS, MOSGUIDE, AND ECMWF 2M TEMPS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
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THERE WILL REMAIN THE CHANCE FOR SHOWERS INTO TONIGHT, ESPECIALLY EARLY IN THE EVENING AS ANOTHER SHORT WAVE/VORT MAX MOVES ACROSS THE AREA. AGAIN, THE BEST FAVORED AREAS ARE THE WESTERN HALF/TWO THIRDS OF THE AREA IN THE EARLY PART OF THE NIGHT. SHOWERS SHOULD BEGIN TO DIMINISH AFTER MIDNIGHT AS THE SHORT WAVE CROSSES THE AREA. ALMOST SEEMS LIKE A BROKEN RECORD; THERE REMAINS THE CHANCE FOR SHOWERS/THUNDERSHOWERS DURING THE DAY SATURDAY INTO SATURDAY EVENING AS ANOTHER SHORT WAVE/VORTICITY MAX PUSHES ACROSS THE AREA. ONCE THIS IMPULSE SLIDES ACROSS THE AREA SATURDAY EVENING, SHOWER CHANCES DROP OFF OVERNIGHT SATURDAY INTO SUNDAY MORNING AS HIGH PRESSURE WILL BEGIN PUSHING INTO THE AREA FROM THE NORTHEAST. CONTINUED A BLEND OF MAV/MET MOS, MOSGUIDE, AND ECMWF 2M TEMPS FOR HIGHS AND LOWS TONIGHT-SATURDAY NIGHT.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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SUNDAY THROUGH WEDNESDAY...THE HIGH WILL CONTINUE TO SETTLE IN OVER THE REGION FROM THE NORTH. WEAK ON SHORE FLOW THROUGH AT LEAST MONDAY WILL HELP TO KEEP HIGHS BETWEEN 5 AND 10 DEGREES BELOW NORMAL EACH DAY. BY WEDNESDAY...THE HIGH WILL HAVE SHIFTED ENOUGH OFF SHORE TO LEAVE THE REGION UNDER SOUTHERLY FLOW BRINGING TEMPERATURES ONCE AGAIN NEAR NORMAL. BUT IT DOESN`T LOOK LIKE THE WARM WEATHER WILL BE AROUND FOR VERY LONG. THURSDAY THROUGH FRIDAY...MODELS HAVE SLOWED THE TIMING OF THE NEXT COLD FRONT SLIGHTLY AS COMPARED TO PREVIOUS RUNS, WITH IT NOW FORECAST TO ARRIVE LATE THURSDAY OR EARLY FRIDAY. THUS...THURSDAY SHOULD ONCE AGAIN BE NEAR NORMAL. THE FRONT WILL BRING THE NEXT PROMISING CHANCES FOR PRECIPITATION ACROSS THE REGION, AS WELL AS TEMPERATURES WELL BELOW NORMAL FOR FRIDAY.
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&& .AVIATION /08Z FRIDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. MVFR AND EVEN IFR CIGS/VSBYS WILL CONTINUE TO AFFECT THE TAF SITES THIS MORNING AS AN AREA OF SHOWERS MOVE THROUGH. THE DISTURBANCE THAT CREATED THESE SHOWERS WILL MOVE THROUGH LATER THIS MORNING, AND SHOWERS SHOULD DISSIPATE AND MOVE EAST OF THE AREA AROUND OR SHORTLY AFTER DAYBREAK. MVFR CONDITIONS SHOULD REMAIN ACROSS THE AREA THROUGH THE MORNING HOURS, BEFORE LIFTING BACK TO VFR AS DAYTIME MIXING TAKES PLACE. SCATTERED SHOWERS ARE AGAIN POSSIBLE TODAY, SO THEY WERE INCLUDED IN THE TAFS. THERE IS THE POTENTIAL FOR THUNDERSTORMS, BUT CONFIDENCE IN OCCURRENCE AND TIMING WAS LOW, SO THEY WERE KEPT OUT FOR NOW. WINDS TODAY WILL GENERALLY BE OUT OF THE EAST 5-10 KNOTS. WE EXPECT MVFR CONDITIONS TO DEVELOP ONCE AGAIN LATER THIS EVENING ACROSS THE TAF SITES AS MOISTURE POOLS AT THE LOW-LEVEL INVERSION. IN FACT, CIGS MAY END UP LOWERING TO IFR FOR MANY AREAS OVERNIGHT. WINDS WILL REMAIN EASTERLY 5-10 KNOTS. OUTLOOK... SATURDAY...MVFR/IFR CIGS EARLY...BECOMING VFR. SCATTERED SHOWERS POSSIBLE. SATURDAY NIGHT THROUGH TUESDAY...MOSTLY VFR.
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&& .MARINE...
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SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED TO CONTINUE THROUGH TONIGHT. HOWEVER, SEAS MAY BEGIN TO APPROACH 4 FEET AND WINDS MAY BEGIN TO GUST AROUND 20 KNOTS OVERNIGHT AS EARLY FLOW INCREASES AS HIGH PRESSURE APPROACHES THE AREA FROM THE NORTH. OUTLOOK... SATURDAY-SATURDAY NIGHT...CONDITIONS MAY APPROACH SMALL CRAFT ADVISORY LEVELS AS EASTERLY FLOW INCREASES AS HIGH PRESSURE BUILDS IN FROM THE NORTH. SUNDAY THROUGH TUESDAY...WINDS AND SEAS SHOULD STAY BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH AT LEAST TUESDAY.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...JOHNSON NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...JOHNSON AVIATION...JOHNSON/ROBERTSON MARINE...JOHNSON/ROBERTSON

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