Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 040130
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
930 PM EDT FRI JUL 3 2015

.SYNOPSIS...
A WEAK HIGH PRESSURE SYSTEM WILL REMAIN OVER NEW ENGLAND TONIGHT,
BEFORE MOVING OFFSHORE ON SATURDAY. MEANWHILE, LOW PRESSURE OVER
THE OHIO VALLEY WILL MOVE ALONG A STALLED FRONTAL BOUNDARY TO OUR
SOUTH AND PASS EAST OF THE DELMARVA PENINSULA ON INDEPENDENCE DAY.
ANOTHER AREA OF HIGH PRESSURE WILL THEN MOVE INTO THE REGION FOR
THE END OF THE HOLIDAY WEEKEND AND MONDAY. A WEAK LOW PRESSURE
SYSTEM MIGHT EASE NORTH INTO THE AREA ON TUESDAY AS ANOTHER COLD
FRONT APPROACHES THE FORECAST AREA BY MIDWEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THE EVENING WATER VAPOR SATELLITE IMAGERY SHOWS A POSITIVELY-
TILTED UPPER TROUGH OVER THE MIDWEST. MOISTURE IS STREAMING AHEAD
OF THE TROUGH FROM THE WESTERN GULF OF MEXICO NORTHEASTWARD TOWARD
THE CENTRAL APPALACHIANS AND MID-ATLANTIC COAST. AT THE SURFACE, A
STATIONARY FRONTAL BOUNDARY WAS POSITIONED TO OUR SOUTH NEAR THE
VA-NC BORDER.

REGIONAL RADAR MOSAIC THIS EVENING SHOWED A BAND OF LIGHT SHOWERS TO
OUR SOUTH AND WEST OVER WESTERN PA/VA/CENTRAL MD THAT WAS
ASSOCIATED WITH DPVA FROM A LEADING MID-LEVEL SHORTWAVE TROUGH
AND ISENTROPIC LIFT. POPS THRU TONIGHT CLOSELY FOLLOW THE LATEST
HRRR, RAP AND NCEP WRF-NMM, WHICH SEEM TO HAVE HAD A GOOD HANDLE
ON THE PROGRESSION OF THESE SHOWERS THUS FAR. PRECIP IS GENERALLY
EXPECTED TO ADVANCE NORTHEASTWARD INTO THE EASTERN SHORE OF MD
THIS EVE, DELAWARE CLOSE TO MIDNIGHT AND EASTERN PA/NJ LATE
TONIGHT INTO THE EARLY MORNING.

THE BEST LIFT WITH THE FRONT AND THE UPPER TROUGH WILL REMAIN
UPSTREAM OF THE AREA TONIGHT. THE CWA WILL BE LOCATED ON THE
COOL/STABLE SIDE OF THE BOUNDARY. THERE IS SOME RESIDUAL DRY AIR IN
THE MID AND LOW-LEVELS. THEREFORE, DO NOT EXPECT THE PRECIP TO BE
STEADY OR HEAVY TONIGHT IN THIS SETUP.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
STILL LOTS OF UNCERTAINTY IN THIS PERIOD. THERE IS CONSIDERABLE
DISAGREEMENT BETWEEN MODELS AND RUN-TO-RUN ON INDIVIDUAL MODEL RUNS.
FOR THE MOST PART, THE MAIN DETERMINISTIC MODELS HAD A SLIGHTLY
DRIER TREND WITH THE 12Z/18Z RUNS. HOWEVER, THIS HAS BEEN THE
CASE THE LAST FEW DAYS, WITH THE 00Z RUNS TENDING TO BE WETTER
SOLUTIONS. AT THIS POINT, THINK THE HIGHEST CHANCES WILL STILL
COME BEFORE 21Z. THINK THAT IT WILL MOSTLY BE A STEADY RAIN GIVEN
A RATHER STABLE ATMOSPHERE IN PLACE. AS FAR AS RAIN AMOUNTS, HAVE
FAVORED LIGHTER AMOUNTS GIVEN THE UNCERTAINTY OF HOW MUCH MOISTURE
ADVECTION WE WILL HAVE. THE THREAT OF THUNDERSTORMS, HEAVY
RAINFALL AND FLOODING LOOKS TO BE DWINDLING GIVEN THESE RECENT
TRENDS.

MOST MODEL SOLUTIONS CONTINUE TO SHOW THE PRECIP LIFTING OUT
QUICKLY FROM MID TO LATE AFTERNOON. THIS TIMING MAY ALLOW FOR
SOME OUTDOOR 4TH OF JULY FESTIVITIES TO TAKE PLACE LATE IN THE
DAY. THE GROUND MAY BE DAMP THOUGH IN PARTS OF THE AREA THAT
RECEIVE THE STEADIER/HEAVIER RAINFALL (MOST LIKELY DELMARVA AND
SOUTHERN NJ).

WITH ALL THE CLOUD COVER IN PLACE, IT LOOKS TO BE A RATHER COOL DAY
(HIGHS IN THE 60S IN THE MOUNTAINS AND 70S ELSEWHERE).

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
ANY LINGERING PRECIP SHUD BE ENDING ERLY SAT EVE WHICH SHUD HAVE
A POSITIVE IMPACT ON ANY FIREWORKS DISPLAYS AND OTHER HOLIDAY
FESTIVITIES.

HIGH PRES WILL THEN BUILD IN FOR SAT NIGHT THRU MON KEEPING THIS
PD DRY OVER MOST, IF NOT ALL OF THE AREA. THE ONLY LOCATION THAT
GUID IMPLIES CUD SEE SOME PRECIP WUD BE OVER THE DELMARVA COME
MON.

BY MON NIGHT INTO TUE, ANOTHER QUICK WV MOVES THRU, THEN THE GFS
IS MUCH FASTER WITH A CDFNT FROM THE W, BRINGING IT THRU BY WED
MRNG AND THE ASSOCD PRECIP. THE CMC AND ECMWF ARE MUCH SLOWER
BRING THE FRONT THRU LATER WED INTO WED NIGHT. IF THE EC IS TO BE
BELIEVED, WITH THE SLOWER FRONTAL TIMING, TUE NIGHT INTO ERLY WED,
CUD BE DRY AND WED CUD BE ON THE HOT SIDE AHEAD OF THE FRONT. THEN
THE ECMWF DEVELOPS WHAT APPEARS TO BE A VERY STRONG WAVE FOR FRI
THAT THE GFS DOESN`T HAVE, AND IS SUBSEQUENTLY DRY.

ONCE AGAIN, CONFIDENCE IS LOWER THAN AVERAGE. THERE WILL BE A CFP.
HAVE SHADED THIS FCST TWD THE MDL CONSENSUS AND THE SLOWER
TIMING, BUT, NOT SURE ON THE MOST LIKELY PDS OF PRECIP AS A RESULT
OF THE UNCERTAINTY. FOR NOW, AM JUST CARRYING LOW POPS FOR FRI, AS
WE HAVE A WEEK TO SEE WHAT, IF ANYTHING, DEVELOPS.

TEMPS WILL START OFF NR NRML AND RISE TO ABV NRML VALUES BY THE
MIDDLE AND END OF THE WEEK.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS EXPECTED THROUGH THE OVERNIGHT WITH CEILINGS AOA
5,000 FEET. SOME LIGHT RAIN SHOWERS MAY BEGIN TO MOVE INTO THE
REGION BY 05Z WITH CHANCES INCREASING FROM SOUTH TO NORTH
OVERNIGHT. THE STEADIEST AND HEAVIEST SHOWERS LOOK TO BE FROM
13-18Z SATURDAY, WHICH WILL CORRESPOND TO THE HIGHEST CHANCE FOR
MVFR CEILINGS/VSBYS FROM PHL/PNE TO THE SOUTHEAST. RDG AND ABE
COULD ESCAPE THE PROSPECTS FOR ANY MVFR RESTRICTIONS. ACY HAS
HIGHEST LIKELIHOOD TO SEE MVFR CONDITIONS WITH THE SLOWEST RISE IN
CEILINGS LATE IN THE DAY. CEILINGS WILL LIKELY LIFT TO VFR AND
BECOME BROKEN BY 19Z OUTSIDE OF ACY WHERE AN ONSHORE FLOW WILL
TEND TO KEEP THEM LOWER. WINDS WILL BE AT OR UNDER 10 KNOTS FROM
THE SOUTH LATE THIS EVENING THEN SHIFTING TO EASTERLY FOR MOST OF
SATURDAY. A WIND SHIFT TO A MORE WESTERLY DIRECTION IS LIKELY TO
START BY SATURDAY EVENING.

OUTLOOK...

SAT NIGHT...SOME MVFR FOG PSBL AT THE MORE RURAL ARPTS, OTHERWISE
VFR.   HIGH CONFIDENCE.

SUN THRU TUE NIGHT...VFR SUN AND SUN NIGHT. HIGH CONFIDENCE. VFR
MON AND TUE OUTSIDE OF ANY SHRA/TSRA MAINLY IN THE AFTNS.

WED...PREDOMINATELY VFR, BUT DECREASING TO MVFR/IFR WITH
INCREASING CHCS OF SHRA/TSRA, ESPECIALLY W AS CDFNT APPROACHES.
MDT CONFIDENCE.

&&

.MARINE...
WINDS AND SEAS SHOULD STAY BELOW SCA CRITERIA TONIGHT INTO TOMORROW
MORNING. BY TOMORROW AFTERNOON, WINDS AND SEAS COULD BUILD TO NEAR
25 KT/5 FT, PRIMARILY ON THE NORTHERN ATLANTIC WATERS. HOWEVER,
THERE IS CONSIDERABLE UNCERTAINTY AND HAVE CAPPED WINDS/SEAS JUST
BELOW SCA THRESHOLD.

OUTLOOK... SAT NIGHT AND SUN...THERE IS STILL SOME UNCERTAINTY
WITH THE STRENGTH AND TRACK OF THE LOW, BUT IT APPEARS THE BEST
CHC OF SEAS ABOVE SCA CONDS WILL BE EARLY SAT NIGHT AND PSBLY SOME
MRGNL WIND. HOWEVER, CONFIDENCE IS LOW ENOUGH AT THE MOMENT TO
HOLD OFF ISSUING ANY FLAGS ATTM. THE BEST CHCS APPEAR TO BE ON THE
NRN WATERS. AFTER ANY SCA LINGERING INTO THE MRNG, THE CONDS SHUD
DECREASE BELOW SCA LATER INTO SUN.

SUN NIGHT THRU WED...NO MARINE FLAGS ARE ANTICIPATED.

&&

.TIDES/COASTAL FLOODING...
WITH CONTINUED WEAK ON SHORE FLOW, HIGH TIDES THIS EVENING AND
SATURDAY EVENING COULD APPROACH THE MINOR FLOODING LEVEL, BUT
RIGHT NOW NO SITES ARE FORECAST TO REACH LEVELS NEEDED FOR A
COASTAL FLOOD ADVISORY. SAT NIGHT AND SUN LOOK TO BE THE SAME WAY.
WHILE SOME SITES MAY APPROACH MINOR TIDAL FLOODING LEVELS, CURRENT
DATA INDICATES THEY WILL REMAIN BELOW CRITERIA.

&&

.RIP CURRENTS...
THERE IS A MODERATE RISK OF RIP CURRENTS ON SATURDAY ALONG THE
NEW JERSEY SHORE GIVEN THE CONTINUED ONSHORE FLOW AND MODERATE
PERIOD SWELLS. THE RISK IS LOW FOR DELAWARE.

&&

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

&&

$$
SYNOPSIS...NIERENBERG
NEAR TERM...KLEIN
SHORT TERM...JOHNSON/KLEIN
LONG TERM...NIERENBERG
AVIATION...GAINES/JOHNSON/NIERENBERG
MARINE...JOHNSON/NIERENBERG
TIDES/COASTAL FLOODING...JOHNSON
RIP CURRENTS...KLEIN



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