Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 301723
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
123 PM EDT SUN AUG 30 2015

.SYNOPSIS...
A WEAKENING COLD FRONT WILL ARRIVE TONIGHT, OTHERWISE HIGH
PRESSURE WILL REMAIN MOSTLY CENTERED NEAR THE MID ATLANTIC REGION
THROUGH MUCH OF THIS WEEK. HOWEVER, A WEAK COLD FRONT SHOULD SLIDE
SOUTH THROUGH OUR REGION THURSDAY NIGHT OR FRIDAY. AN OFFSHORE
LOW AND HIGH PRESSURE TO OUR NORTHEAST WILL PROBABLY PROVIDE
SOMEWHAT COOLER TEMPERATURES NEXT FRIDAY INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SHORT WAVE TROUGH WILL ARRIVE INTO THE NORTHEAST LATER TODAY, AND
AS IT DOES IT SHOULD TEND TO WEAKEN. A WEAK COLD FRONT AT THE
SURFACE IS TIED TO THIS FEATURE, AND WITH SOME MOISTURE ON THE
INCREASE SOME ADDITIONAL SHOWERS AND A THUNDERSTORM ARE EXPECTED TO
DEVELOP TO OUR WEST. THERE IS SOME INSTABILITY DURING THE DAY, WITH
THIS PROBABLY BEST ACROSS THE WESTERN ZONES. HOWEVER, THE FORECAST
SOUNDINGS MOSTLY SHOW A SKINNY CAPE PROFILE WHICH TENDS TO KEEP
UPDRAFTS ON THE WEAKER SIDE. THE BULK OF THE LIFT ASSOCIATED WITH
THE TROUGH AXIS IS FORECAST TO BE TO OUR WEST DURING PEAK HEATING
WITH THE ACTUAL SHORT WAVE AND THE RIGHT ENTRANCE REGION OF AN UPPER-
LEVEL JET. HOWEVER, TERRAIN INFLUENCES ALONG WITH WEAK SURFACE
CONVERGENCE COULD BE ENOUGH AND THEREFORE WE KEPT A SLIGHT CHC POP
ACROSS THE NORTHWESTERN ZONES. THIS WAS DELAYED A BIT THOUGH GIVEN
SLOWER CUMULUS DEVELOPMENT THUS FAR. HIGH LEVEL CLOUDINESS IS
STREAMING NORTHWARD FROM MARYLAND AND DELAWARE.

IT WILL BE RATHER WARM TO HOT ACROSS MUCH OF THE CWA THIS AFTERNOON,
HOWEVER DEW POINTS MAY LOWER A LITTLE BIT BY LATE DAY IN SOME AREAS
DUE TO SIGNIFICANT HEATING OF THE BOUNDARY LAYER. THE PRESSURE
GRADIENT IS NOT FORECAST TO BE ALL THAT TIGHT, THEREFORE LIGHT
ENOUGH FLOW WILL RESULT IN A SEA BREEZE ONCE AGAIN THROUGH THIS
AFTERNOON.

THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS,
THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN TO ASSIST. NO MAJOR
CHANGES WERE MADE TO THE HIGH TEMPERATURES ATTM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
ANY ISOLD SHWRS OR TSTMS WILL COME TO AN END AND THEN
EXPECT JUST A PCLDY SKY WITH GRADUALLY INCREASING DEW PTS, AS THE
HIGH REMAINS THE DOMINANT WX FEATURE AS WE CLOSE OUT AUGUST AND
METEOROLOGICAL SUMMER.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
DRAFT: TO BE UPDATED AT 330 PM.

500 MB:  A STRONG WARM RIDGE OF HIGH PRESSURE WILL PREVAIL ALONG THE
EAST COAST THROUGH SUNDAY WITH ONLY A MINOR WEAKENING OF THIS RIDGE
OVER OUR AREA LATE WEDNESDAY INTO FRIDAY AS A STRONG SHORT WAVE
DIVES SEWD TOWARD THE MARITIMES (55N/55W). THAT PERMITS A LITTLE
MORE NORTHERLY COMPONENT ALOFT AND SO AN ASSOCIATED BOUNDARY SLIPS
SOUTHWARD.

TEMPERATURES: AUGUST THROUGH THE 29TH WAS AVERAGING NEAR OR ABOVE
NORMAL. KMPO AND KGED WERE THE ONLY TWO OF THE 8 CLIMATE SITES
BELOW NORMAL. KTTN KACY AND KPHL WERE AVERAGING ~1 TO ~2F ABOVE
NORMAL AND WILL WARM THESE LAST TWO DAYS OF THE MONTH.

CALENDAR DAY DEPARTURES TUESDAY THROUGH THURSDAY WILL BE 6 TO 12
DEGREES ABOVE NORMAL WITH THE LARGEST POSITIVE DEPARTURES N AND NW
OF KPHL. THURSDAY THROUGH SUNDAY SHOULD STILL AVERAGE 5 DEGREES OR
MORE ABOVE NORMAL.  HOW MUCH COOLING OCCURS FRIDAY AND BEYOND IS
DEPENDENT ON THE STRENGTH OF ONSHORE FLOW.  IT APPEARS THE GREATEST
IMPACT OF COOLING ONSHORE FLOW WILL BE THE SOUTHERN NJ AND DE
COASTS.


FORECAST BASIS: UNLESS OTHERWISE NOTED, 12Z/30 GFS MOS WAS THE
PRIMARY GUIDANCE MONDAY NIGHT-TUESDAY NIGHT, 12Z/30 MEX MOS
WEDNESDAY AND WEDNESDAY NIGHT, THEN THE 1521Z/30 WPC GRIDDED
ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT-SKY-WIND
FROM THURSDAY ONWARD.

HAZARDS...

A HEAT WAVE WILL BE IN PROGRESS THROUGH THURSDAY FOR THE I-95
CORRIDOR EASTWARD TO NEAR THE COASTS, ITS DURATION SHOULD BE AT
LEAST 4 DAYS WHETHER OR NOT IT BEGINS THIS AFTERNOON OR MONDAY.
THE QUESTION, DOES IT BREAK ANYTIME FRIDAY-SUNDAY OR JUST GO ON
AND ON THROUGH EARLY NEXT WEEK. IT IS POSSIBLE THE I-95 CORRIDOR
COULD SEE AN EXTENDED HEAT WAVE BEYOND 4 DAYS. MAX HEAT INDEX VALUES
IN THIS HEAT WAVE SO FAR ARE FORECAST TO BE IN THE MID TO UPPER
90S.

THUNDERSTORM DRENCHING RAINS? NEAR THE COOL FRONT FRIDAY BUT OVERALL
AS PER WPC, THE DRY SPELL IS GOING TO LAST QUITE AWHILE, POSSIBLY
THROUGH THE START OF LABOR DAY WEEK.

THE DAILIES...

MONDAY NIGHT-THURSDAY...FAIR AND HOT AFTERNOONS WITH PATCHY FOG
POSSIBLE LATE AT NIGHT OVER THE COUNTRYSIDE OF NW NJ AND E PA.
LIGHT WINDS TEND TO BE NW DURING EACH AFTERNOON. SMALL CHC OF
CONVECTION E PA AND NNJ WED AFTN AND THU AFTN BUT MAY BE TOO
LITTLE TO MENTION IN OUR 330 PM FCST.  STILL UNDECIDED.

THU NIGHT-FRIDAY...A SWD MOVING COLD FRONT MAY SPAWN HEAVY SOUTHWARD
MOVING CONVECTION BUT ONLY IN A PWAT OF 1.6 INCHES. SLOW MOVERS-
GULLY WASHERS WHERE THEY OCCUR BUT LITTLE PREDICTABILITY ATTM EXCEPT
MOST OF THE ACTIVITY SHOULD REMAIN JUST INLAND.  POTENTIALLY STILL
90F VCNTY KPHL SWWD AND WESTWARD ON FRIDAY. DEWPOINTS HIGHER,
AROUND 70F AND 1400J ML CAPE. 0-6KM BULK SHEAR IS POOR FOR ANY
SVR. STRATUS FOG POTENTIAL AT NIGHT AND IN THE MORNING I-80
NORTHWARD.

NEXT WEEKEND...FAIR AND VERY WARM. SLIGHT CHANCE FOR AFTN/EVENING
CONVECTION POCONOS TO THE LEHIGH VALLEY AND KRDG BUT AGAIN
PROBABLY TOO SMALL A POP TO MENTION.

OVERALL CONFIDENCE THESE NEXT 6 DAYS: ABOVE AVERAGE.

&&


.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR WITH SOME CUMULUS DEVELOPING AROUND 5000 FEET,
ALONG WITH HIGH LEVEL CLOUDS MOVING THROUGH. SOUTHWESTERLY WINDS UP
TO 10 KNOTS, WHICH SHOULD TURN MORE SOUTHERLY AT KACY AND PERHAPS
KILG DUE TO A SEA/BAY BREEZE. AN ISOLATED SHOWER OR THUNDERSTORM
MAY APPROACH THE KABE TO KRDG AREAS TOWARD EVENING.

TONIGHT...VFR OVERALL. A WEAKENING COLD FRONT SHOULD ALLOW A SHOWER
OR THUNDERSTORM TO ARRIVE MAINLY NEAR THE KABE AND KRDG AREAS THIS
EVENING, HOWEVER COVERAGE IS EXPECTED TO BE RATHER LOW.
SOUTHWESTERLY WINDS 5-10 KNOTS, BECOMING LIGHT AND VARIABLE AT MANY
OF THE TERMINALS.

OUTLOOK...
DRAFT: WILL UPDATE AT 330 PM.

MONDAY NIGHT THROUGH WEDNESDAY...VFR CONDITIONS EXPECTED THOUGH
LOCALIZED MVFR/IFR CONDITIONS WITH FOG/ST POSSIBLE EACH MORNING,
MAINLY NEAR KABE-KRDG. LIGHT WIND, TENDS BE NW EACH AFTERNOON.

THURSDAY...MOSTLY VFR CONDITIONS. ISOLATED THUNDERSTORMS POSSIBLE
LATE.  IFR CIGS/VSBY POSSIBLE N OF I-80 LATE THU NIGHT.

FRIDAY...VFR WITH BRIEF IFR CONDS POSSIBLE IN TSTMS.  MVFR OR IFR
CIGS DEVELOPING IN NELY FLOW NEAR AND N OF I-80 WITH POSSIBLE IFR
VSBY IN FOG AT NIGHT.

OVERALL LONG TERM AVIATION FCST CONFIDENCE: ABOVE AVERAGE.

&&

.MARINE...
NO MARINE FLAGS ARE ANTICIPATED THRU THE NR AND SHORT TERM
PDS. SEAS WILL GENLY BE IN THE 2 TO 3 FT RANGE. WIND WILL GENLY
BE SW IN THE 10 TO 15 KT RANGE WITH GUSTS AS HIGH AS 20 KT.

OUTLOOK...
DRAFT: TO BE UPDATED AT 330 PM.

MONDAY NIGHT THROUGH THURSDAY...WINDS AND SEAS SHOULD STAY WELL
BELOW SMALL CRAFT ADVISORY CRITERIA. WATER TEMPERATURES ARE ABOVE
NORMAL.

FRIDAY...ATLC SEAS MAY INCREASE AS AN EASTERLY FLOW DEVELOP BUT
ATTM, BELOW SCA CRITERIA.

&&

.RIP CURRENTS...
A LONG PERIOD EAST TO SOUTHEAST SWELL, 10-11 SECONDS, CONTINUES TO
ROLL IN ALONG THE COAST. THIS COMBINED WITH WINDS TURNING MORE
SOUTHERLY AND INCREASING SOME THROUGH THE DAY WILL RESULT IN TRICKY
CONDITIONS AT TIMES WITHIN THE SURF ZONE ESPECIALLY DURING TIDE
CHANGES. AS A RESULT THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF
DANGEROUS RIP CURRENTS THROUGH THIS EVENING ALONG THE NEW JERSEY
SHORE AND THE DELAWARE BEACHES.

THE OUTLOOK IS FOR GENERALLY LOW ENHANCED CONDITIONS THIS WEEK WITH
A SLIGHTLY SUBSIDING 1-2 FOOT 10 SECOND SE SWELL. ITS POSSIBLE WE
WILL STILL NEED TO CARRY A MDT RISK ON MONDAY BASED ON THE VERY
SLOW TO SUBSIDE SWELL OF TODAY-SUNDAY.

NEXT FRIDAY ONWARD MAY SEE THE RISK INCREASE,  POSSIBLY TO MODERATE
NEXT WEEKEND OR MONDAY DEPENDING ON THE EVENTUAL DEVELOPMENT OF
OFFSHORE LOW PRESSURE AND ITS WESTWARD SWEEPING SWELLS.

&&

.CLIMATE...
THIS SECTION WILL PROBABLY DISCARD LATER TONIGHT.

AUGUST: KPHL (POR 1872) AND KACY (POR 1874), BARRING ANY MORE RAIN
THIS MONTH, WILL BE 10TH DRIEST ON RECORD WITH 0.98 AND 1.25"
RESPECTIVELY. THE KILG 1.54 INCHES IS 13TH DRIEST ON RECORD
PROVIDED NO MORE RAIN FALLS BEFORE 1 AM TUESDAY.

LISTING THE SEASONS 90F OR WARMER DAYS AS INFO FOR YOU TO ADD ONTO
AS THE WEEK PROGRESSES.

KPHL 28, MEAN 21. IF WE ADD 5 MORE DAYS 90F BETWEEN NOW AND SEPT
9 (TOTAL PROJECTED AT LEAST 33) AND KPHL WILL HAVE THE 18TH
HIGHEST SEASONAL TOTAL OF 90 OR HIGHER. POR TO 1872

KABE 12  POR MEAN 17
KACY 16  POR MEAN 10
KILG 11  POR MEAN 20

SAMPLING OF OTHER LOCATION TOTALS FOR 2015 ARE BELOW.
KPNE 30
KVAY 15
KRDG 17
KTTN 20
KGED 18
KFWN 6

&&

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

&&

$$
SYNOPSIS...GORSE/JOHNSON/DRAG 123P
NEAR TERM...GORSE
SHORT TERM...NIERENBERG
LONG TERM...DRAG 123P
AVIATION...DRAG/GORSE/JOHNSON 123P
MARINE...DRAG/JOHNSON/NIERENBERG 123P
RIP CURRENTS...GORSE/DRAG 123P
CLIMATE...DRAG 123P



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