Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 261936
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
336 PM EDT SUN APR 26 2015

.SYNOPSIS...
A LARGE AND COMPLEX LOW PRESSURE SYSTEM OVER THE WESTERN NORTH
ATLANTIC WILL CONTINUE TO MOVE SLOWLY OUT TO SEA DURING THE EARLY
AND MIDDLE PARTS OF THE NEW WEEK. MEANWHILE, HIGH PRESSURE WILL
BUILD INTO OUR REGION GRADUALLY FROM THE NORTHWEST AND WEST.
ANOTHER AREA OF LOW PRESSURE IS FORECAST TO PASS OFF THE NORTH
CAROLINA COAST ON THURSDAY BEFORE MOVING OUT TO SEA. HIGH PRESSURE
IS EXPECTED TO BUILD INTO OUR REGION FROM THE WEST ON FRIDAY
BEFORE PASSING OFF THE COAST DURING THE COMING WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
FOR TONIGHT...HIGH PRES SHOULD CONT TO BUILD SWD INTO THE N-CNTRL
US AND SLIGHTLY EWD INTO THE MID-ATLANTIC REGION. MEANWHILE LOW
PRES IS FCST TO RETRO-GRADE SWWD OVER NOVA SCOTIA IN ASSOCN WITH
AN UPPER TROF SWINGING SWD FROM SERN CANADA INTO THE NERN US. THE
RESULT WILL BE AN INCRG E-W PRES GRADIENT OVER OUR AREA WHICH
SHOULD BE ABLE TO MAINTAIN A LIGHT N-NNW FLOW OVERNIGHT SKIES WILL
BE MOSTLY CLEAR BUT SOME CLOUDINESS IS POSSIBLE AHEAD OF THE UPPER
TROF. OVERNIGHT MINS SHOULD BE SLIGHTLY WARMER THAN LAST
NIGHT...BUT SOME MID-30S ARE POSSIBLE IN SOME BETTER- RADIATING
AREAS. WILL INCLUDE MENTION OF PATCHY FROST BUT EXTENT DOES NOT
SEEM WIDE ENOUGH TO JUSTIFY ANOTHER ADVISORY.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
FOR MONDAY THE SURFACE PATTERN WILL BE SIMILAR TO TODAY WITH HIGH
PRES OVER THE MID-WEST AND LOW PRES WELL OFF THE EAST COAST WITH A
CENTER NEAR NOVA SCOTIA. NORTH WINDS WILL CONTINUE BUT SHOULD BE
SMWHAT STRONGER THAN TODAY WITH A STRONGER GRADIENT BETWEEN THE
HIGH AND LOW. MAX TEMPS MONDAY AFTN COULD BE A LITTLE COOLER THAN
TODAY DUE TO INCREASED CLOUDINESS...ESPECIALLY FROM PHL NORTH.

THERE WILL BE A CHANCE OF SHOWERS ON MONDAY...ESPECIALLY IN THE
AFTN...AS AN UPPER-LEVEL HGT/THERMAL TROF ROTATES SWD ACROSS THE
AREA. COOLER TEMPS ALOFT WILL RESULT IN INCREASED INSTBY ALONG
WITH MID-LEVEL MOISTURE...HOWEVER THE LOW LEVELS OF THE ATMOS WILL
REMAIN RATHER DRY WITH INVERTED VEE TYPE SOUNDING. THUS THE PRECIP
FROM SHOWERS THAT DEVELOP WILL TEND TO EVAPORATE BEFORE REACHING
THE GROUND. WE HAVE INCLUDED SLGT CHC POPS FOR MOST OF OUR FCST
AREA WITH SLGTLY HIER CHC POPS WELL N/W OF PHL.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
WE SHOULD REMAIN UNDER THE INFLUENCE OF A MID LEVEL LOW OFF NOVA
SCOTIA DURING THE PERIOD FROM MONDAY NIGHT INTO TUESDAY NIGHT.
SOME CLEARING IS EXPECTED DURING THE COURSE OF MONDAY NIGHT WITH
CUMULUS ANTICIPATED TO DEVELOP ON TUESDAY DUE TO DAYTIME HEATING.
A NORTH TO NORTHWEST WIND AROUND 10 TO 15 MPH IS FORECAST FOR
MONDAY NIGHT INTO TUESDAY MORNING. WIND SPEEDS ARE EXPECTED TO
DIMINISH A BIT FOR TUESDAY AFTERNOON AS THE SURFACE PRESSURE
GRADIENT IN OUR REGION RELAXES.

A WEAK MID LEVEL RIDGE IS FORECAST TO APPROACH FROM THE WEST AND
NORTHWEST AND IT SHOULD BE OVERHEAD ON WEDNESDAY AND WEDNESDAY
NIGHT.

THE MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH THEIR
HANDLING OF THE DEVELOPING MID LEVEL TROUGH OVER THE EASTERN
STATES FOR THURSDAY AND FRIDAY. ALSO, THERE IS IMPROVING BUT NOT
YET IDEAL CONSENSUS REGARDING THE SURFACE LOW. WE WILL CONTINUE TO
FAVOR THE ECMWF SOLUTION BASED ON ITS BETTER RUN TO RUN
CONSISTENCY.

THE SURFACE LOW SHOULD BE OFF CAPE HATTERAS ON THURSDAY AFTERNOON
BEFORE MOVING NORTHEASTWARD AND OUT TO SEA. OUR REGION IS
ANTICIPATED TO STAY ON THE NORTHWESTERN FRINGE OF ITS MAIN
IMPACTS. THE EXACT TRACK OF THE LOW REMAINS UNCERTAIN SO WE MAY OR
MAY NOT GET SOME RAIN IN ADDITION TO THE CLOUD COVER, ESPECIALLY
ON THE COASTAL PLAIN. WE HAVE KEPT THE 30 PERCENT CHANCE OF
SHOWERS FOR THE TIME BEING. AN EAST WIND AROUND 10 MPH ON THURSDAY
IS EXPECTED TO INCREASE TO 10 TO 15 MPH ON THURSDAY NIGHT AS IT
BACKS TO THE NORTHEAST, THEN TO THE NORTH.

THE COMPLEX MID LEVEL TROUGH IS FORECAST TO MOVE OUT OVER THE
WESTERN NORTH ATLANTIC FOR THE WEEKEND. A MID LEVEL SHORT WAVE IS
EXPECTED TO DROP DOWN FROM THE NORTHWEST AT THAT TIME. THE FEATURE
IS ANTICIPATED TO HAVE LIMITED MOISTURE ASSOCIATED WITH IT. A
SUBSTANTIAL RIDGE FROM THE WEST IS FORECAST TO BUILD OVER THE
EASTERN STATES FOR THE FIRST FULL WEEK OF MAY.

TEMPERATURES SHOULD NOT BE FAR FROM NORMAL DURING THE PERIOD FROM
TUESDAY THROUGH SUNDAY.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDS ARE EXPECTED TO PREVAIL AT ALL OUR TAF SITES FOR THE
NEXT 24 HOURS OR SO. AFTN STRATO-CU HAVE DEVELOPED OVER MUCH OF
THE AREA BUT BASES ARE HIGH...WELL ABOVE BKN050. THESE CLOUDS WILL
TEND TO DISSIPATE DURING THE EVENING BUT MAY LINGER A WHILE AFTER
SUNSET... ESPECIALLY AROUND RDG/ABE/TTN. A WEAK SFC TROF OVER THE
AREA IS RESULTING IN LIGHT WINDS OVER THE AREA THIS AFTERNOON.
WINDS SHOULD REMAIN LIGHT TONIGHT BUT WITH A PREVAILING NW
DIRECTION GRADUALLY DEVELOPING.

FOR MONDAY...A STRONGER SFC PRES GRADIENT IS EXPECTED TO DEVELOP
WITH WILL RESULT IN STRONGER NW WINDS. SOME GUSTS TO AROUND 20KT
ARE LIKELY DURG THE AFTN. CONSIDERABLE CLOUDINESS WILL DEVELOP BUT
AGAIN THE CLOUD BASES SHOULD BE 5K FT OR HIGHER. SOME CLOUDS WILL
BUILD UP HIGH ENOUGH TO PRODUCE SHOWERS BUT MUCH OF THE RAIN IS
LIKELY TO EVAPORATE BEFORE REACHING THE GROUND...THUS LITTLE IF
ANY LIMITS TO VSBY ARE EXPECTED.

OUTLOOK...

MONDAY NIGHT THROUGH WEDNESDAY NIGHT...MAINLY VFR.

THURSDAY AND THURSDAY NIGHT...MAINLY VFR WITH A CHANCE OF
SHOWERS. AN EAST TO NORTHEAST WIND AROUND 10 KNOTS IS EXPECTED
ALONG WITH ITS POTENTIAL IMPACT ON OPERATIONS AT KPHL.

FRIDAY...MAINLY VFR.

&&

.MARINE...
WINDS AND SEAS ARE CURRENTLY RATHER QUIET OVER THE FCST WATERS
AND SHOULD REMAIN SO FOR TONIGHT AND MUCH OF THE DAY TOMORROW.
HWVR...FOR MONDAY AFTN WINDS WILL INCREASE FROM THE NW AND SEAS
WILL BEGIN TO BUILD. CONDS ARE EXPECTED TO REMAIN BELOW SCA
CRITERIA DURING THE DAY BUT WILL CONTINUE TO DETERIORATE INTO
MONDAY EVENING WHEN A SCA WILL GO INTO EFFECT.

OUTLOOK...

MONDAY NIGHT AND TUESDAY MORNING...A SMALL CRAFT ADVISORY IS IN
EFFECT FOR A NORTHWEST TO NORTH WIND GUSTING TO 25 OR 30 KNOTS.

TUESDAY AFTERNOON THROUGH THURSDAY MORNING...NO MARINE HEADLINES
ARE ANTICIPATED.

THURSDAY AFTERNOON THROUGH FRIDAY...A SMALL CRAFT ADVISORY MAY BE
NEEDED FOR WIND GUSTS OF 25 TO 30 KNOTS AND FOR WAVES ON OUR OCEAN
WATERS IN EXCESS OF 5 FEET. THE WIND DIRECTION IS ANTICIPATED TO
BACK GRADUALLY FROM THE EAST TO THE NORTH. THERE IS THE POTENTIAL
FOR GALE FORCE GUSTS IF LOW PRESSURE OVER THE OCEAN TRACKS CLOSER
TO THE COAST THAN CURRENTLY EXPECTED.

&&

.FIRE WEATHER...
WIND GUSTS AROUND 20 MPH ARE EXPECTED FOR TUESDAY MORNING WITH
GUSTS FORECAST TO DROP INTO THE 10 TO 15 MPH RANGE DURING THE
AFTERNOON. RELATIVE HUMIDITY VALUES ARE ANTICIPATED TO DROP AROUND
30 PERCENT IN MUCH OF OUR REGION ON TUESDAY AFTERNOON. PRESENTLY,
IT DOES NOT APPEAR AS THOUGH BOTH ELEMENTS WILL COME TOGETHER TO
CREATE AN ENHANCED CONCERN FOR WILDFIRE SPREAD. HOWEVER,
CONDITIONS MAY GET CLOSE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM MONDAY TO NOON EDT TUESDAY FOR
     ANZ430-431-450>455.

&&

$$

SYNOPSIS...IOVINO
NEAR TERM...AMC
SHORT TERM...AMC
LONG TERM...IOVINO
AVIATION...AMC/IOVINO
MARINE...AMC/IOVINO
FIRE WEATHER...IOVINO


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