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Area Forecast Discussion
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000
FXUS61 KPHI 230700
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
300 AM EDT WED JUL 23 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE EASTWARD ALLOWING FOR A BETTER
RETURN FLOW TODAY AHEAD OF A POTENT COLD FRONT. THE FRONT SHOULD MOVE
THROUGH OUR AREA LATE TONIGHT INTO THURSDAY MORNING. HIGH PRESSURE
WILL FILL IN BEHIND THE DEPARTING FRONT THROUGH THE FIRST HALF OF
THE WEEKEND BEFORE A COMPLEX SYSTEM APPROACHES SUNDAY SPILLING
INTO THE NEW WORK WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
FAIR EARLY THIS MORNING...PATCHY FOG TOWARD 10Z...MAINLY NW NJ.
PATCHY CLOUDINESS FORMING...AOA 5000 FT AS A SEPARATE KI AXIS
DEVELOPS OVER NJ/EPA TOWARD 12Z.

TODAY...LITTLE CHANGE FROM PRIOR FORECASTS. MODEL GUIDANCE STATES
WIDESPREAD LOWER 90S (NEAR 18C 850 MB AND 925MB HOTTEST TEMPS ARE
JUST WEST AND NORTHWEST OF OUR FCST AREA). POCONOS AND IMMEDIATE
ATLC SHORE A BIT COOLER. ECMWF SEEMS TO HOLD BACK SLIGHTLY. THE
FCST TEMPS ISSUED AT 330 AM MAY BE A DEGREE TOO WARM. 

HEAT INDEX UPPER 90S....CLOSE TO 100 BUT NO HEAT ADVY ISSUED ATTM.

TSTMS PROBABLY RESTRICTED TO NW NJ AND E CENTRAL AND NE PA AFTER
21Z...POSSIBLY A SECOND CLUSTER CROSSING CHES BAY? TT 48+ SWI -2
KI INCREASING TO 38C VCNTY POCS AND E VA. APPEARS TO BE A SEE TEXT
CASE...UNLIKELY SVR THROUGH 00Z DUE TO LACK OF BULK SHEAR...500MB
WINDS UNDER 30 KT AND MLCAPE CLOSER TO 1600J.

NOTE THAT THERE SHOULD BE CU FIELDS FORMING THIS MORNING OVER NNJ
IN A LEADING EDGE AREA OF KI 33C BUT WITH LITTLE OR NO PRIMARY 
FORCING...AM NOT EXPECTING TO YIELD ANY LATE MORNING TSTMS IN NNJ
AS THIS LEADING PATCH OF INSTABILITY SHOVES ENE TO LI BY 18Z.

TODAYS FCST BASIS: NAM TEMPS (50 50 BLEND OF 00Z/23 NAM METMOS AND
THE NAM 2M TEMPS). OTHERWISE...OTHER ELEMENTS A 50 50 BLEND OF
THE 00Z/23 NAM/GFS GUIDANCE IN THIS 330 AM ISSUANCE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
SLOW SEWD PROGRESS OF THE COLD FRONT INTO THE UNSTABLE AIRMASS SHOULD
YIELD BANDS OF TSTMS INTO THE NIGHT BUT NOT NECESSARILY WIDESPREAD.
ONE OR 2 TSTMS COULD BE SVR BUT BULK SHEAR FOR SVR IS MARGINAL AT
WORST AND ONLY THE TT AND SOME CAPE ALLOW FOR MODEST ISOLATED SVR
POTENTIAL.

PWAT 1.8 INCHES OFFERS A CHANCE OF NARROW PATHS OF 2 INCH RAINS 
BENEATH THE BIGGEST STORMS.

LIGHTNING STRIKES MIGHT BE THE BIG PROBLEM? 

FCST BASIS; 50 50 BLEND OF THE 00Z/23 GFS/NAM GUIDANCE IN THIS 330
AM ISSUANCE EXCEPT MOSTLY NAM METMOS TEMPS.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
THE BASE OF THE TROUGH BEGINS TO FLATTEN OUT BY FRIDAY, THOUGH NOT 
ENTIRELY BECOMING ZONAL. THIS YIELDS SLIGHTLY BELOW NORMAL 
TEMPERATURES AND DECREASED CHANCES FOR CONVECTION GIVEN A DRIER 
AIRMASS IN PLACE. STILL A BIT UNCERTAIN ABOUT THE SATURDAY EVENING 
TIMEFRAME AS SOME OF THE OPERATIONAL GUIDANCE SWINGS A PIECE ENERGY 
THROUGH THE BASE OF THE TROUGH WHICH COULD TOUCH OFF A COUPLE 
STRAY/ISOLATED SHOWERS...BETTER EAST THAN WEST WITH BETTER MOISTURE 
POOLING AND SEABREEZE INTERACTION.

RIDGING BUILDS INTO THE WEST SENDING STRONGER SHORTWAVES OF ENERGY 
INTO THE TROUGH OVERHEAD ALLOWING FOR ANOTHER BOUT OF DEEPER 
TROUGHING. EXPECT UNSETTLED WEATHER THROUGH THE REMAINDER OF THE 
LONGTERM AS A SERIES OF EMBEDDED WAVES PUSHES THROUGH ALOFT TOUCHING 
OFF SHOWERS AND THUNDERSTORMS.

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY AND SURROUNDING AREAS.

EARLY THIS MORNING BEFORE 12Z...PRIMARILY VFR WITH SCT CLOUDS AOA
4000 FT. PATCHY 2 TO 5 MI FOG POSSIBLE IN THE COUNTRYSIDE TAF
LOCATIONS BUT CONFIDENCE IS LESS THAN IT WAS AT THIS TIME YDY.
TEMP-DEWPOINT SPREADS AT 3 AM ARE JUST TOO LARGE FOR FOG. LIGHT
S-SW WIND.

TODAY AFTER 12Z...VFR SCT AOA 5000 FT. BRIEFLY BKN CIGS NEAR 5000
FT VCNTY KABE AND KRDG THIS AFTN AND CHC OF A TSTM THERE AFTER
22Z WITH GUSTY WEST WIND 30-40 KT. OTHERWISE NON TSTM GRADIENT
WINDS SUGGEST SW WIND GUST 17 KT THIS AFTN MOST TAF LOCATIONS.

TONIGHT...VFR CIGS WITH A BETTER CHC OF BRIEF IFR CONDS IN TSTMS.
LIGHT SW WIND SHIFT N TOWARD MORNING WHEN PATCHY IFR ST/FOG MIGHT
FORM IN THE FRONTAL ZONE OR WHERE IT RAINS THIS EVENING. STRONG
GUSTY WEST WIND IN A TSTM POSSIBLE BETWEEN 00Z AND 04Z FOR KTTN
KPNE KPHL AND KILG BUT LESS CONFIDENCE THAN FOR KABE AND KRDG
OUTLINED IN THE PREVIOUS PARAGRAPH.

OUTLOOK...
THURSDAY...MVFR AND IFR CONDITIONS AT TIMES IN SHOWERS AND THUNDERSTORMS.
PATCHY FOG THU MORNING.

THURSDAY NIGHT THROUGH SATURDAY...MAINLY VFR.

SUNDAY...SUB-VFR POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
NO HEADLINES THROUGH TONIGHT.

MAINLY S-SW WIND G UNDER 20 KT SHIFT TO NORTH TOWARD DAWN THURSDAY.

WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD BE 2 TO 4 FEET. WAVES ON 
DELAWARE BAY ARE EXPECTED TO BE 2 FEET OR LESS.

SCATTERED THUNDERSTORMS TONIGHT.

OUTLOOK...
THURSDAY THROUGH SUNDAY...HIGH PRESSURE OVERHEAD WILL KEEP SEAS AND 
WINDS BELOW SCA CRITERIA.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...HEAVENER
NEAR TERM...DRAG 3A
SHORT TERM...DRAG 3A
LONG TERM...HEAVENER
AVIATION...DRAG/HEAVENER 3A
MARINE...DRAG/HEAVENER 3A






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