Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 282238 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 638 PM EDT MON JUL 28 2014 .SYNOPSIS...
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LOW PRESSURE MOVING ACROSS NEW ENGLAND EARLY THIS EVENING IS SHOVING A COLD FRONT OFF THE MID ATLANTIC COAST. WEAK HIGH PRESSURE WILL FOLLOW LATER TUESDAY THROUGH WEDNESDAY. IT THEN MERGES INTO THE WESTERN ATLANTIC HIGH PRESSURE SYSTEM LATE THIS WEEK. MEANWHILE...THE FRONT WILL BE LURKING JUST OFF THE COAST AS A STATIONARY FRONT.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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A MID LEVEL SHORT WAVE TROUGH WILL CONTINUE TO LIFT OVER NEW ENGLAND THIS EVENING. MEANWHILE, SURFACE LOW PRESSURE LOCATED OVER SOUTHEASTERN NEW HAMPSHIRE AROUND 600 PM WILL LIFT NORTHWARD ACROSS MAINE. THE LOW WILL CONTINUE TO PULL A COLD FRONT THROUGH OUR REGION. THE COLD FRONT EXTENDED FROM MORRIS COUNTY, ACROSS UPPER BUCKS COUNTY TO SOUTHERN BERKS COUNTY AROUND 600 PM. THE BOUNDARY SHOULD REACH PHILADELPHIA ABOUT 800 PM, ATLANTIC CITY AROUND 1000 PM AND FENWICK ISLAND NEAR MIDNIGHT. RAIN SHOWERS ASSOCIATED WITH THE COLD FRONT WERE DISSIPATING SLOWLY WITH THE GRADUAL LOSS OF DAYTIME HEATING. THE MORE SUBSTANTIAL BATCH OF SHOWERS IN OUR REGION EXTENDED FROM AROUND ALLENTOWN TO THE LANCASTER AREA EARLY THIS EVENING. WE WILL CONTINUE TO MENTION SCATTERED TO ISOLATED SHOWERS WITH THE FRONT UNTIL ABOUT 900 PM. AFTERWARD, WE ARE ANTICIPATING A SLOW DECREASE IN CLOUD COVER AS DRY AIR CONTINUES TO FILTER INTO OUR REGION FROM THE NORTHWEST. LOW TEMPERATURES SHOULD BE MAINLY IN THE 50S AND LOWER 60S.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
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A NICE TUESDAY AHEAD AS COOLER, DRIER AIR CONTINUES TO MOVE IN ACROSS THE AREA AS WEAK HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST. WITH PW VALUES BELOW ONE INCH AND NO SIGNIFICANT SHORT WAVE/VORTICITY IMPULSES, TUESDAY IS EXPECTED TO BE DRY ACROSS THE AREA. TEMPERATURES WILL BE COOLER THAN THE LAST COUPLE OF DAYS AS 925/850 MB TEMPS AND THICKNESSES DECREASE INTO TUESDAY. USED A BLEND OF MAV/MET MOS, MOSGUIDE, AND MIXED 925 MB TEMPS FOR HIGHS ON TUESDAY WHICH ENDS UP BEING SEVERAL DEGREES BELOW NORMAL.
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&& .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
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500 MB: A LARGE TROUGH IN THE EAST WILL SLOWLY WEAKEN LATE THIS WEEK INTO EARLY NEXT WEEK. TEMPERATURES: ABOUT 5 DEGREES BELOW NORMAL WEDNESDAY WARMING TO NEAR NORMAL THIS COMING WEEKEND AND EARLY NEXT WEEK. FORECAST BASIS: UNLESS OTHERWISE NOTED THE LONG TERM PERIOD OF THIS FORECAST IS GENERALLY BASED ON A 50 50 BLEND OF THE 12Z/28 NAM/GFS MOS FOR THE PERIOD TUESDAY NIGHT - WEDNESDAY NIGHT... THE 12Z/28 GFS MOS THURSDAY AND THURSDAY NIGHT AND THEN THEREAFTER (FRIDAY ONWARD) THE 1522Z/28 WPC GRIDDED GUIDANCE FOR ALL ELEMENTS EXCEPT HAVE APPLIED THE WARMER 12Z/28 MEXMOS TEMPS. ALL THIS WAS CHECKED AGAINST THE 12Z/28 ECMWF TO ENSURE WE`RE IN THE BALLPARK (BARRING MIDDAY OVC SKIES AND RAIN) WITH ECMWF CYCLICALLY PERSISTENT 18Z 2METER TEMPERATURES. THE PRECIPITATION PROBABILITY GUIDANCE WAS CHECKED AGAINST THE 09Z/28 SREF POPS FOR .01 IN 3 HRS THROUGH 00Z FRIDAY AND THEREAFTER THE 12Z/28 GEFS 6HR POPS FOR 0.05 . THE DAILIES... IT SORT OF LOOKS LIKE WE`RE PRIMARILY IN A WEAK SURFACE RIDGE REGION THIS 6 DAY PERIOD AND NOT FAVORABLE FOR MUCH RAIN. BASICALLY FOR NOW ITS A GENERALLY FAIR WEATHER FORECAST THIS 6 DAY PERIOD. THERE IS A CHANCE FOR LATE DAY OR EVENING CONVECTION NE PA AND NW NJ LATER IN THE WEEK BUT FOR NOW IS CHANCEY AND LOW CONFIDENCE. AS FOR THE LURKING QUASI STATIONARY ALONG THE COAST... IT MAY DRIFT CLOSER TO THE SHORE BY THE WEEKEND AS A WARM FRONT WITH ITS CONVECTION POSSIBLY SPREADING ASHORE BUT CONFIDENCE FOR THIS SCENARIO IS ALSO BELOW AVERAGE. IT DOES APPEAR THIS QUASI STATIONARY BOUNDARY WILL EVENTUALLY DISSIPATE AND AS IT DOES...HIGHER HUMIDITY SHOULD SLOWLY RETURN TO THE AREA LATE THIS WEEKEND INTO EARLY NEXT WEEK. TEMPERATURES AND POPS AS DESCRIBED ABOVE IN THE FORECAST BASIS.
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&& .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS EXPECTED ACROSS THE TAF SITES THROUGH TONIGHT AND INTO TUESDAY. A LINE OF SHOWERS EXTENDED FROM AROUND KRDG TO KABE AND KMMU AROUND 2200Z, MODEL GUIDANCE INDICATES THE SHOWERS WILL DISSIPATE/WEAKEN AS THEY MOVE THROUGH OUR AREA THIS EVENING. WESTERLY WINDS GUSTING 20-25 KNOTS WILL CONTINUE THROUGH SUNDOWN, THEN THE GUSTS SHOULD DROP OFF, AND WINDS WILL BECOME NORTHWESTERLY BEHIND THE COLD FRONT OVERNIGHT INTO TUESDAY. WINDS MAY BEGIN SWITCHING TO WEST OR SOUTHWEST AGAIN BY LATE TUESDAY INTO TUESDAY EVENING, AND A SEABREEZE MAY FORM ALONG THE COAST BY THE AFTERNOON. OUTLOOK... TUESDAY NIGHT-WEDNESDAY NIGHT...MAINLY VFR. THURSDAY- SATURDAY...MAINLY VFR. ISOLATED SHOWERS/THUNDERSTORMS POSSIBLE EACH DAY BUT LOW CONFIDENCE ON OCCURRENCE. PATCHY IFR FOG OR STRATUS IS POSSIBLE FRI NIGHT.
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&& .MARINE...
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THE SMALL CRAFT ADVISORY FOR THE DELAWARE BAY AND THE SOUTHERN HALF OF THE ATLANTIC COASTAL WATERS WAS EXTENDED THROUGH MIDNIGHT TONIGHT AS WINDS ARE GUSTING AROUND 25-30 KNOTS NOW, AND SHOULD CONTINUE INTO THE EVENING AHEAD OF THE FRONTAL BOUNDARY. AS THE FRONTAL BOUNDARY MOVES THROUGH, THE GUSTS WILL SWITCH FROM WEST TO NORTHWEST AND DROP OFF SLIGHT, AND SEAS SHOULD LOWER AS WELL. THE SEAS MAY REMAIN LONGER ON THE NORTHERN WATERS A FEW MORE HOURS, SO WE LEAVE THE NORTHERN HALF ENDING AT 6 AM TUESDAY. OUTLOOK... TUESDAY NIGHT-SATURDAY...NO HEADLINES ANTICIPATED. LOOKS LIKE GOOD WEATHER FOR BEING ON THE WATERS IN THIS TIME FRAME. WE ARE MONITORING THE GFS OPERATIONAL RUN DEPICTION (FOR SEVERAL FORECAST CYCLES) OF A TROPICAL SYSTEM IN THE ATLANTIC BASIN FOR EARLY NEXT WEEK BUT THE ECMWF OPERATIONAL VERSION STILL DOESNT HAVE IT.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ430-431- 452>455. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ450-451. && $$ SYNOPSIS...DRAG NEAR TERM...IOVINO SHORT TERM...ROBERTSON LONG TERM...DRAG/ROBERTSON AVIATION...DRAG/ROBERTSON/IOVINO MARINE...DRAG/ROBERTSON

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