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Area Forecast Discussion
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000
FXUS61 KPHI 291327
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
927 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/...
NO BIG CHANGES TO THE FORECAST TODAY. THE ONLY CHANGES MADE WAS TO
HOURLY TEMP/DEWPOINT GRIDS AND TO INCREASE SKY COVER SLIGHTLY.

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 /13Z 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...
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...NONE.

&&

$$
SYNOPSIS...HEAVENER
NEAR TERM...JOHNSON/ROBERTSON
SHORT TERM...JOHNSON
LONG TERM...HEAVENER
AVIATION...HEAVENER/JOHNSON
MARINE...HEAVENER/JOHNSON






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