Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 231624
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1224 PM EDT SAT AUG 23 2014

.SYNOPSIS...
HIGH PRESSURE WILL SLOWLY BUILD SOUTH OUT OF CANADA TOWARDS OUR
REGION THROUGH THE WEEKEND. THE HIGH WILL BE ENTRENCHED OVER OUR
REGION THROUGH AT LEAST MID WEEK BEFORE IT WEAKENS. A COLD FRONT
COULD PUSH THROUGH THE REGION LATE IN THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THERE HAS BEEN A PERSISTENT AREA OF SHOWERS ASSOCIATED WITH A WEAK
VORTICITY IMPULSE THAT HAVE SLOWLY DRIFTING EASTWARD. WITHOUT MUCH
FLOW ALOFT, THEY ARE SLOW TO MOVE. HOWEVER, AS THE WEAK IMPULSE
CONTINUES TO SLIDE EASTWARD. POPS HAVE BEEN INCREASED JUST
NORTHEAST OF PHL FOR THE NEXT FEW HOURS. POPS HAVE ALSO BEEN
INCREASED WITH A PERIOD OF SHOWERS ACROSS THE DELMARVA AS WELL FOR
THE 12;30 PM UPDATE. TEMPERATURES WERE ADJUSTED SLIGHTLY DOWNWARD IN
AREAS NW THAT HAVE SEEN SHOWERS THIS MORNING AND RAISED WHERE
SUNSHINE HAS COME OUT IN ABUNDANCE ACROSS SOUTHERN DELAWARE WITH
THE 12;30 PM UPDATE.

THERE WILL REMAIN A CHANCE FOR SCATTERED SHOWERS ELSEWHERE THROUGHOUT
THE AFTERNOON AS A STRONGER SHORT WAVE/VORTICITY IMPULSE MOVES
ACROSS THE AREA. VERTICAL MOISTURE IS EXPECTED TO DRY LATER IN THE
DAY AS THE IMPULSE APPROACHES AS HIGH PRESSURE CONTINUES TO PUSH
FARTHER SOUTH INTO THE AREA. HOWEVER, THERE SHOULD BE ENOUGH TO
INTERACT WITH THE SHORT WAVE TO PRODUCE SOME SHOWER ACTIVITY. WITH
PW VALUES NEAR 1.5 INCHES, THERE REMAINS THE POTENTIAL FOR SOME
HEAVY RAIN WITH ANY SHOWER DEVELOPMENT. THERE IS REALLY NO
INSTABILITY EXPECTED TODAY, SO WE DO NOT HAVE THUNDERSTORMS IN THE
FORECAST, ALTHOUGH IT WOULD NOT BE SURPRISING TO SEE AN COUPLE OF
ISOLATED LIGHTNING STRIKES.

FOR HIGHS, USED A BLEND OF MAV/MET MOS, MOSGUIDE, AND MIXED 925 MB
TEMPS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
THE SHORT WAVE/VORT MAX WILL BE MOVING THROUGH OUR SOUTHERN AREAS
THIS EVENING, WHILE HIGH PRESSURE CONTINUES TO BUILD IN FROM THE
NORTH. MEANWHILE, PW VALUES WILL BE DROPPING OFF QUITE SHARPLY AS
DRIER AIR MOVES IN. THERE MAY BE A FEW ISOLATED SHOWERS EARLY IN THE
EVENING, BUT WHATEVER IS OUT THERE SHOULD DISSIPATE AND/OR MOVE
SOUTHWARD THROUGH THE EVENING, AND THE REMAINDER OF THE NIGHT SHOULD
BE RAIN FREE.

FOR OVERNIGHT LOWS USED A BLEND OF MAV/MET MOS AND MOSGUIDE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
NOT MANY CHANGES THROUGH MID WEEK FROM THE PREVIOUS FORECAST.
STILL EXPECTING AN EXTENDED PERIOD OF DRY WEATHER AS THE SURFACE
HIGH BUILDS OVER OUR REGION, AND IN THE UPPER LEVELS, A SHORT WAVE
RIDGE PROPAGATES SOUTHEAST OVER OUR REGION MONDAY INTO TUESDAY.
WITH THE COOLER AIR SETTLING IN ON SUNDAY, SHOULD START WITH BELOW
NORMAL TEMPERATURES, BUT HAVE A STEADY WARMING TREND THROUGH MID
WEEK, ESPECIALLY AS LOW LEVEL SOUTHWESTERLY FLOW DEVELOPS
WEDNESDAY.

THURSDAY THROUGH SATURDAY REMAINS THE PERIOD OF MOST INTEREST OVER
THE NEXT WEEK, BUT ALSO WITH THE GREATEST UNCERTAINTY. THERE ARE
THREE FEATURES THAT WILL BE WATCHED OVER THE NEXT FEW DAYS THAT
COULD HAVE BIG IMPACTS WITH OUR WEATHER IN THE LATE WEEK PERIODS.
FIRST...THE TOPICAL SYSTEM WHICH COULD DEVELOP OVER THE NEXT FEW
DAYS. WHILE NEARLY ALL OF THE LONG RANGE MODELS HAVE THIS SYSTEM
STAYING WELL OFF SHORE, AND THUS NOT DIRECTLY IMPACTING US, IT
COULD HELP TO WEAKEN THE SURFACE HIGH OVER THE MID ATLANTIC
EARLIER THAN PREVIOUSLY FORECAST, RESULTING IN AN INDIRECT IMPACT.
SECOND, THE SURFACE COLD FRONT, WHICH LONG RANGE MODELS EITHER
KEEP PUSHING BACK THE ARRIVAL IN OUR REGION, OR KEEP IT NORTH OF
US ALL TOGETHER. AT THIS POINT, IT STILL SEEMS LIKELY THAT THE
FRONT WILL PUSH THROUGH OUR REGION, BUT PROBABLY NOT UNTIL FRIDAY
AS THE THIRD FEATURE, A BROAD UPPER LEVEL TROUGH, SLIDES EAST OVER
THE GREAT LAKES REGION. ALL THAT SAID, OUR NEXT GOOD CHANCE FOR
RAIN WILL COME WHEN THE FRONT ARRIVES, ALONG WITH TEMPERATURES
WELL BELOW NORMAL. HOWEVER, GIVEN THE UNCERTAINTY IN THE TIMING
AND TRACK OF THE FRONT, HAVE KEPT POPS THROUGH THE LATE WEEK
PERIOD IN THE 20S AND 30S.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

MANY TAF SITES HAVE GONE BACK AND FORTH BETWEEN MVFR AND VFR
CEILINGS TODAY, THE HEAVIEST SHOWERS APPEAR TO HAVE DIMINISHED FOR
THE TIME BEING. IF ANY SHOWERS DO OCCUR, THEY COULD BRIEFLY REDUCE
CIGS/VSBYS.

VFR CONDITIONS ARE EXPECTED FOR THE OVERNIGHT HOURS AS DRIER AIR
FILTERS IN AS HIGH PRESSURE BUILDS IN FROM THE NORTH.

WINDS WILL BE MOSTLY OUT OF THE EAST TO NORTHEAST 5-10 KNOTS OR LESS
THROUGH THE PERIOD.

OUTLOOK...
SUNDAY THROUGH WEDNESDAY...VFR CONDITIONS EXPECTED.

&&

.MARINE...
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE OCEAN, AND HAS BEEN
EXPANDED TO INCLUDE THE ENTIRE NEW JERSEY ATLANTIC COAST. SEAS ARE
EXPECTED TO BUILD LATER TODAY AND CONTINUE INTO TONIGHT AS THE EAST
TO NORTHEASTERLY FLOW INCREASES. WINDS MAY GUST AROUND 20-25 KNOTS
AS WELL LATER TODAY INTO TONIGHT.

OUTLOOK...
SUNDAY...SEAS AND WINDS ARE EXPECTED TO SUBSIDE BELOW SMALL CRAFT
ADVISORY EARLY IN THE DAY.

MONDAY THROUGH WEDNESDAY...WINDS AND SEAS WILL LIKELY STAY BELOW
SMALL CRAFT ADVISORY CONDITIONS.

&&

.RIP CURRENTS...
A MODERATE RISK OF RIP CURRENTS REMAINS TODAY INTO TONIGHT AS SEAS
ARE EXPECTED TO BUILD IN THE PERSISTENT EASTERLY FLOW. THE MODERATE
RISK MAY CONTINUE INTO SUNDAY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT SUNDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...JOHNSON
NEAR TERM...GAINES/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...JOHNSON
AVIATION...GAINES/JOHNSON/ROBERTSON
MARINE...JOHNSON/ROBERTSON
RIP CURRENTS...





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