Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 290811 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 411 AM EDT TUE JUL 29 2014 .SYNOPSIS... WEAK HIGH PRESSURE WILL FILTER IN TODAY AND WEDNESDAY PUSHING THE PREVIOUS COLD FRONT FURTHER OFFSHORE. EVENTUALLY THE AFOREMENTIONED HIGH PRESSURE MERGES WITH THE WESTERN ATLANTIC HIGH PRESSURE SYSTEM LATE THIS WEEK. MEANWHILE...THE OLD COLD FRONT WILL BE LURKING JUST OFF THE COAST AS A STATIONARY FRONT. THIS FRONT BEGINS TO BACK TOWARDS THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WILL CONTINUE TO SEE COLD AND DRY AIR ADVECTION THROUGH THE DAY IN THE WAKE OF THE COLD FRONT. MAV AND MET CAME IN A BIT LOWER FOR HIGHS THAN THE PREVIOUS RUN, NOW KEEPING MUCH OF THE REGION IN THE 70S. GIVEN THAT MOST SITES TOPPED OUT IN THE LOWER 80S YESTERDAY, AND TODAY SHOULD BE EVEN A FEW DEGREES LOWER, HAVE FOLLOWED THIS TREND WITH THE FORECAST. SHOULD SEE SOME CUMULUS DEVELOPMENT, BUT WITH THE DRY LOW LEVELS, DO NOT EXPECT ANY PRECIPITATION TODAY DESPITE THE MID AND UPPER LEVEL TROUGH REMAINING WEST OF THE REGION. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... CLEARING SKIES, LIGHT WINDS, AND DRY AIR WILL SET THE STAGE FOR PRIME RADIATIONAL COOLING CONDITIONS ACROSS THE REGION. THUS EXPECT LOWS TO RANGE FROM THE UPPER 40S IN THE POCONOS TO THE LOWER 60S NEAR THE COAST AND IN THE URBAN CORRIDOR. FOR MANY OF OUR CLIMATE SITES, THIS IS NEAR RECORD LOWS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HEMISPHERICALLY THE OPERATIONAL ENVELOPE SEEMS PRETTY MUCH IN LINE WITH ONE ANOTHER THROUGH SATURDAY BEFORE DIVERTING. THE ANOMALOUS EAST COAST TROUGH REMAINS THE DOMINATE FEATURE/DRIVING FORCE THROUGH THE END OF THE WORK WEEK. THEREAFTER, THE STRONGER TROUGH BEGINS TO BREAK DOWN WITH ITS CLOSED LOW OPENING UP AND MOVING OFF TOWARDS THE NORTH AND EAST OVER THE WEEKEND. A MUCH MORE BROAD BASED TROUGH REMAINS OVERHEAD THROUGH THE END OF THE PERIOD. WEDNESDAY - THURSDAY...EXPECTING MOSTLY DRY DAYS ACROSS THE REGION OUTSIDE THE POSSIBILITIES OF ISOLATED INSTABILITY SHOWERS ACROSS THE NORTHERN PORTIONS OF THE CWA. COLD POOL INTERACTION WITH A FEW PASSING SHORTWAVES MAY BE ENOUGH TO GET AIRMASS SHOWERS TO OCCUR, THOUGH THE BETTER CHANCE LOOKS TO OCCUR TO THURSDAY, STILL SLIGHT CHANCE, WITH MOR MOISTURE IN THE COLUMN COMPARED TO WEDNESDAY. TEMPERATURES LOOK TO REMAIN BELOW NORMAL, THOUGH DEPENDING ON HOW MUCH SUNSHINE WE RECEIVE ON THURSDAY WE COULD COME CLOSE. FRIDAY...TRANSITIONAL DAY WITH THE LOOKS OF AN INVERTED TROUGH SITTING OFF THE ATLANTIC COAST...THE OLD BAROCLINIC ZONE THAT PUSHED THROUGH ON MONDAY. ONSHORE FLOW TO THE EAST AND SOUTHEASTERLY FLOW INLAND, AROUND THE DEPARTING SURFACE RIDGE, HELP TO ADVECT IN SLIGHTLY COOLER TEMPERATURES BUT ATLANTIC MOISTURE. UPSLOPE FLOW COMBINED WITH SOME HEATING, WEAK SURFACE CONVERGENCE, MAY BE ENOUGH TO GENERATE SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE INTERIOR ZONES WITH BETTER STABILITY CLOSER TO THE COAST. TEMPERATURES SHOULD END UP BEING BELOW NORMAL...AGAIN. SATURDAY - SUNDAY...LOTS OF UNCERTAINTY AT THIS JUNCTURE IN TERMS OF THE INVERTED TROUGH`S PLACEMENT AND SURFACE LOW, ALONG THE FRONT/TROUGH, TRACK. THE 00Z SUITE, OUTSIDE OF THE EURO, SEEMS REASONABLE WITH KEEPING A MAJORITY OF THE CONVECTIVE ACTIVITY TO OUR SOUTH AND JUST OFFSHORE ON SATURDAY...SUNDAY IS A DIFFERENT STORY. GEFS IS SHOWING DECENT CHANCES FOR AFTERNOON SHOWERS AND THUNDERSTORMS THAT BISECT THE REGION...EC ENSEMBLES HAVE SOMETHING SIMILAR. THE LATEST 00Z EC CAME IN MUCH MUCH WETTER SATURDAY AND SUNDAY COMPARED TO THE OTHER MEDIUM RANGE GUIDANCE, AND WITHOUT SEEING THE ENSEMBLES UNCERTAIN HOW MUCH STOCK TO PUT INTO ITS SOLUTION AT THIS TIME. THE GFS ANC GGEM HAVE THE SURFACE LOW PRESSURE ALONG THE FRONT MOVING THROUGH, EC HAS IT 24 HOURS EARLIER ON SATURDAY...SOMETHING TO CONTINUE TO WATCH. MONDAY...SLIGHT DRYING TREND EXPECTED ON MONDAY THOUGH NOT ENTIRELY VOID OF ANY SHOWERS WITH COLD AIR STILL ALOFT WITH A FEW MORE SHORTWAVES SHEARING ACROSS OVERHEAD. MORE MOISTURE AND HEAT ADVECTS IN AND COULD PUSH TEMPERATURES BACK TO NORMAL. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. SCT TO BKN CUMULUS CLOUDS AROUND 050 ARE POSSIBLE THROUGH THE DAY TIME HOURS, BUT OTHERWISE EXPECT FEW CLOUDS. NORTHWESTERLY WINDS WILL SHIFT TO WESTERLY BETWEEN 15 AND 18Z AND GENERALLY REMAIN WESTERLY THROUGH THE REST OF THE TAF PERIOD. THE ONE EXCEPTION IS AT KACY WHERE A SEA BREEZE COULD ARRIVE BETWEEN 18 AND 21Z...SHIFTING WINDS TO SOUTHEASTERLY. AFTER 00Z...EXPECT WINDS TO BECOME LIGHT...GENERALLY 5KT OR LESS AT ALL TAF SITES. OUTLOOK... WEDNESDAY - THURSDAY...MOSTLY VFR. ISOLATED SHOWER OR THUNDERSTORM POSSIBLE MAINLY NORTH OF PHL. FRIDAY - SATURDAY...MOSTLY VFR. WIDELY SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE EACH DAY, THOUGH CONFIDENCE IS LOW ON DEVELOPMENT. PATCHY IFR FOG OR STRATUS IS POSSIBLE FRI NIGHT. && .MARINE... WINDS WILL CONTINUE TO DECREASE ON THE ATLANTIC WATERS ADJACENT TO NORTHERN NJ. THUS ANTICIPATE THAT THE SMALL CRAFT ADVISORY WILL EXPIRE ON TIME AT 6 AM. AFTER 6AM...EXPECT WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY TODAY AND TONIGHT WITH WINDS GENERALLY STAYING BELOW 15 KT AND SEAS BETWEEN 2 AND 3 FEET. OUTLOOK... WEDNESDAY - SATURDAY...SUB-SCA CONDITIONS EXPECTED. SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE EACH AFTERNOON WITH BETTER CHANCES FRIDAY AND SATURDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ450-451. && $$ SYNOPSIS...HEAVENER NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...HEAVENER AVIATION...HEAVENER/JOHNSON MARINE...HEAVENER/JOHNSON

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