Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 250659
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
259 AM EDT SAT APR 25 2015

.SYNOPSIS...
WEAK HIGH PRESSURE COVERS OUR AREA EARLY TODAY. LOW PRESSURE OVER
THE LOWER OHIO VALLEY WILL PASS OFF THE NORTH CAROLINA COAST SUNDAY.
THAT LOW BECOMES PART OF LARGE LOW PRESSURE CIRCULATION OVER THE
NORTHWEST ATLANTIC EARLY NEXT WEEK. A LOW PRESSURE SYSTEM OVER
THE NORTHERN GULF OF MEXICO TUESDAY NIGHT EMERGES OFF THE
SOUTHEASTERN SEABOARD LATE WEDNESDAY AND THURSDAY AND HEADS
NORTHEAST.

&&

.NEAR TERM /THROUGH TODAY/...
330 AM PACKAGE: NOT MUCH CHANGE IN THE FROST/FREEZE HAZARD AS
RADIATIONAL COOLING VARIES BASED ON THE SFC WIND STIRRING BUT
OVERALL...THE ADVY/WARNING IS REASONABLE AND VERIFYING.

TODAY...VARIABLE HIGH CLOUD COVER. THE THICKER SKYCOVER FROM FAR
SE PA AND SNJ SOUTHWARD. SPRINKLES MAY DEVELOP TOWARD 6 PM OVER
TALBOT/CAROLINE AND SOUTHERN SUSSEX COUNTIES ON THE SW EDGE OF OUR
FCST AREA. FORECAST TEMPERATURES TODAY WERE A 1/3RD BLEND OF THE
00Z/25 GFS/NAM MOS AND 00Z/25 ECMWF 2M TEMPS. THE ECMWF IS QUITE
COOL UNDER THE CLOUDS OVER THE DELMARVA AND HAVE MODIFIED THE
NCEP MOS DOWNWARD THERE. WARMEST TEMPS IN OUR FCST AREA TODAY
SHOULD BE IN NORTHERN NJ WHERE THERE SHOULD BE MORE SUNSHINE.

A NICE DAY WITH MUCH LESS WIND THAN THE PREVIOUS WED-THU-FRIDAY
AFTERNOONS.

DAYTIMES TEMPS WILL BE WARMING A BIT EXCEPT THE DELMARVA WHERE IT
WILL BE CHILLY TODAY AND MAXIMUM TEMPS ALMOST 15 DEGREES BELOW
NORMAL WHILE MAXIMUM TEMPERATURES AROUND ALLENTOWN AND MOUNT
POCONO NEWD THROUGH NNJ SHOULD ONLY BE 8 TO 10 DEGREES BELOW
NORMAL.

A WEAK WIND SHIFT BOUNDARY WILL BE FORMING JUST TO OUR NORTH LATE
IN THE DAY WITH WESTERLY WINDS GUSTING TO 15 MPH DURING THE
AFTERNOON IN PA AND NNJ BUT SEA BREEZES SHOULD DEVELOP COASTAL NJ
AND COASTAL DE. WINDS ON THE DELMARVA WILL BE LIGHT WHERE LESS
MIXING IS EXPECTED DUE TO HEAVIER SKYCOVER.

&&

.SHORT TERM /TONIGHT/...
TONIGHT...THICK HIGH CLOUD ALONG AND SOUTH OF I-78, WITH THE NORTHERN
PORTION OF THE FORECAST RAIN SHIELD A BLEND OF HPC QPF, 50 50
00Z/25 NAM/GFS MOS AND MULTI MODEL .10 IN 6 HRS. THAT MEANS MAINLY
THE SOUTHERNMOST 40 MILES OF OUR CWA, TALBOT COUNTY, QUEEN ANNES
AND CAROLINE COUNTIES IN MD AND SUSSEX COUNTY DE, POSSIBLY KENT
COUNTY DE AND POSSIBLY THE SRN TIP OF NJ. THIS CLOUD COVER TODAY
AND CLOUD COVER/RAIN TONIGHT IS ASSOCIATED WITH THE LOW REDEVELOPING
NEAR THE NC COAST. A WIND SHIFT FROM LIGHT WEST TO NORTH-NORTHEAST
PROGRESSES FROM NORTH TO SOUTH THROUGH OUR CWA DURING THE NIGHT.

PATCHY FROST IS IN THE FCST N OF I-78 TONIGHT. NO NEW FROST ADVY
ATTM DUE TO THE UNCERTAINTY OF THE NORTHERN EDGE OF THICK CLOUD
COVER. IT ALREADY FROZE UP THERE THIS MORNING SO EARLY SUSCEPTIBLE
BLOOMS WERE PROBABLY DAMAGED.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE LOW PRESSURE WILL THEN EXIT EAST AND OUT TO SEA THROUGH THE
COURSE OF SUNDAY, BUT THERE COULD BE SOME LEFTOVER PRECIP THAT
LINGERS OVER THE DELMARVA INTO SUNDAY MORNING, AND WE GRADUALLY
DIMINISH POPS TO CHANCE AND THEN LOWER THROUGH THIS PERIOD.
ELSEWHERE THROUGH THE FORECAST AREA, A DRY SUNDAY IS ANTICIPATED
WITH SOME CLOUDS AND GENERALLY LIGHT NORTHERLY WINDS.

MONDAY COULD PRESENT A FEW SHOWERS FOR OUR AREA AS AN UPPER
DISTURBANCE/UPPER LOW LINGERS AROUND THE NORTHEAST STATES OR JUST TO
THEIR EAST. MODEL FORECAST SOUNDINGS PREDICT CONVECTIVE TEMPERATURES
TO BE REACHED MONDAY, SO THERE WILL BE INCREASING CLOUDS THROUGH THE
DAY ALONG WITH SOME ISOLATED/SCATTERED SHOWERS EXPECTED AS COOLER
AIR ALOFT ASSOCIATED WITH THE UPPER LOW LINGERS NEARBY.

THE UPPER LOW PULLS AWAY OUT TO SEA INTO TUESDAY, AND WEAK HIGH
PRESSURE FROM THE WEST GRADUALLY BUILDS ACROSS OUR REGION, LASTING
THROUGH THE DAYTIME WEDNESDAY. WE HAVE KEPT A DRY FORECAST THROUGH
THIS PERIOD, WITH RATHER LIGHT NORTHERLY WINDS AND NEAR AVERAGE END
OF APRIL TEMPERATURES. THE TRICKY AND HIGHLY UNCERTAIN PART OF THE
FORECAST THEN INVOLVES THE DEVELOPMENT AND TRACK OF A POTENTIALLY
STRONG COASTAL SYSTEM THAT MAY BEGIN TO AFFECT OUR REGION WEDNESDAY
NIGHT AND LASTING THROUGH THURSDAY TO THURSDAY NIGHT. THERE
CONTINUES TO BE A WIDE RANGE OF SOLUTIONS FROM THE OPERATIONAL
MODELS TO VARIOUS ENSEMBLE DATA REGARDING THE TRACK, EVOLUTION, AND
INTENSIFICATION OF LOW PRESSURE, MOST LIKELY FROM AROUND THE
NORTHERN GULF OF MEXICO REGION WEDNESDAY BEFORE ITS POTENTIAL
EMERGENCE OFF THE EAST COAST THURSDAY. WITH THE GREATER UNCERTAINTY
THROUGH THIS PERIOD, WE LEANED MORE TOWARD WPC GUIDANCE FOR MOST
ELEMENTS, INCLUDING TEMPERATURES, WINDS, AND POPS, WITH ADDITIONAL
COLLABORATION WITH NEIGHBORING OFFICES.

&&

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

THROUGH 12Z...VFR CLEAR WITH SCT-BKN CLOUDS AOA 15000 FT ARRIVING
SE PA AND S NJ SOUTHWARD AFTER 09Z. LIGHT NORTH NORTHWEST WIND.

TODAY DURING THE DAY...SCT-BKN AOA 15000 FT MAY BRIEFLY THIN LATE
IN THE DAY. LIGHT WEST - NORTHWEST WIND BECOMING WEST MIDDAY WITH
GUSTS TO 15 KT POSSIBLE DURING THE AFTERNOON IN NJ/PA BUT SEABREEZES
DEVELOP ALONG COASTAL SECTIONS MID AND LATE AFTN.

TONIGHT...CIGS AOA 10000 FT, ESPECIALLY AFTER 03Z/26. A SPRINKLE
POSSIBLE KPHL/KILG/KMIV KACY BUT NOT IN THE FCST ATTM. IT MAY BE
TOO DRY IN THE LAYER UNDER 8000 FT. LIGHT WEST WIND SHIFTING N-NE
DURING THE NIGHT. PLEASE SEE TAFS FOR TIMING DETAILS AS A WIND
SHIFT BOUNDARY SAGS SOUTHWARD.

OUTLOOK...

SUNDAY...MAINLY VFR CONDITIONS, AS ANY SUB-VFR IN RAIN TO START
ACROSS SOUTHERN AREAS WILL IMPROVE BACK TO VFR.

MONDAY...MAINLY VFR CONDITIONS; ALTHOUGH, SOME ISOLATED SHOWERS ARE
POSSIBLE. GUSTY NORTH TO NORTHWEST WINDS, WITH GUSTS TO 20 KNOTS.

TUESDAY AND WEDNESDAY...MAINLY VFR EXPECTED; ALTHOUGH, CONDITIONS
MAY DETERIORATE LATE WEDNESDAY NIGHT DEPENDING ON THE TIMING AND
TRACK OF A POSSIBLE COASTAL LOW PRESSURE.

&&

.MARINE...
DISCONTINUING SCA AT 330 AM. SUB SCA CONDITIONS THROUGH TONIGHT
WITH NORTHWEST TO NORTHEAST WINDS THIS MORNING BECOMING WESTERLY
MIDDAY THEN SEA BREEZES DURING LATE AFTERNOON. LIGHT WINDS TONIGHT
BECOMING N-NE LATE.

OUTLOOK...
SUNDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED AT THIS TIME. AN
AREA OF LOW PRESSURE IS FORECAST TO PASS BY TO OUR SOUTH, BUT IT
SHOULD NOT BE CLOSE ENOUGH TO RAISE WINDS OR SEAS TO SCA LEVELS.

MONDAY...CONTINUED MAINLY SUB-SCA CONDITIONS; ALTHOUGH, SOME WIND
GUSTS TO AROUND 20 KNOTS PLUS ARE POSSIBLE.

TUESDAY AND WEDNESDAY...MOSTLY SUB-ADVISORY CONDITIONS THROUGH THIS
PERIOD; ALTHOUGH, SOME HIGHER WINDS AND SEAS MAY BEGIN TO OCCUR LATE
WEDNESDAY NIGHT DEPENDING ON THE TIMING AND TRACK OF POSSIBLE
COASTAL LOW PRESSURE. LOW CONFIDENCE.

&&

.FIRE WEATHER...
DRY CONDITIONS ARE EXPECTED ONCE AGAIN TODAY, WITH MINIMUM RH
VALUES ONCE AGAIN RANGING FROM 20 TO 30 PERCENT. HOWEVER, WINDS
WILL BE CONSIDERABLY LIGHTER, WITH GUSTS GENERALLY NEAR OR BELOW
15 MPH THROUGH THE DAY.  NO ACTION ATTM.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR PAZ060>062-
     101>106.
     FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR PAZ070-071.
NJ...FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR NJZ001-007>010-
     012-013-015>022-027.
     FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR NJZ014-023>026.
DE...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR DEZ001>004.
MD...FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR MDZ008.
     FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MDZ012-015-019-
     020.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     ANZ450>455.

&&

$$
SYNOPSIS...KLINE
NEAR TERM...DRAG 3A
SHORT TERM...DRAG 3A
LONG TERM...KLINE
AVIATION...DRAG/KLINE 3A
MARINE...DRAG/KLINE 3A
FIRE WEATHER...3A


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