Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 270122
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
922 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 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/...
AN UPPER-LEVEL TROUGH IS LOCATED FROM ABOUT THE CANADIAN MARITIMES
WESTWARD TO THE GREAT LAKES THEN DOWN INTO THE OHIO VALLEY. THE
WATER VAPOR IMAGERY THIS EVENING SHOWS SEVERAL WELL DEFINED SHORT
WAVES EMBEDDED WITHIN THE OVERALL UPPER-LEVEL TROUGH. THESE WILL
SHIFT SOUTHWARD OVERNIGHT AND TEND TO KEEP SOME MID LEVEL MOISTURE
IN PLACE. THE MAIN FORECAST CHALLENGE IS THE COVERAGE OF THE CLOUDS.
THEY HAVE TENDED TO THIN OUT WITH THE LOSS OF DAYTIME HEATING FOR
THE MOST PART, HOWEVER THERE ARE MORE LURKING JUST TO THE NORTH. THE
FORECAST SOUNDINGS HINT THAT THEY MAY OOZE SOUTHWARD DURING THE
NIGHT, HOWEVER JUST HOW FAR SOUTH AND TO THE EXTENT OF THEIR
COVERAGE IS OF SOME LOWER CONFIDENCE.

A SEA BREEZE WORKING ITS WAY WESTWARD IS JUST ABOUT TO THE DELAWARE
RIVER FOR CENTRAL/SOUTHERN NEW JERSEY /AS OF 0045Z/, ALTHOUGH IT IS
NOW WEAKENING. THIS FEATURE IS MARKED BY A WIND SHIFT TO THE SOUTH-
SOUTHEAST IN ITS WAKE AS WINDS AHEAD OF IT ARE FROM A NORTHERLY
DIRECTION. THEREFORE, SHOWED A BIT FASTER COOLING IN ITS WAKE ALONG
WITH A LITTLE INCREASE IN THE DEW POINTS.

THE WINDS ARE EXPECTED TO BE ON THE LIGHT SIDE THROUGH THE NIGHT,
HOWEVER WITH SOME CLOUDS PROBABLY HOLDING ON AT TIMES THE LOWS ARE
ANTICIPATED TO BE A BIT WARMER THAN LAST NIGHT. OVERALL, ANY FROST
IS EXPECTED TO BE RATHER PATCHY. NO MAJOR CHANGES WERE MADE TO THE
LOW TEMPERATURES ATTM.

&&

.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-V 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 /01Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

REST OF TONIGHT...VFR. A CEILING AT 6000-9000 FEET SCATTERING OUT
FOR MOST TERMINALS OVERALL. NORTH TO NORTHWEST WINDS 5-8 KNOTS
BECOMING LOCALLY LIGHT AND VARIABLE, HOWEVER SOUTHEASTERLY THIS
EVENING MAINLY FOR AREAS NEAR AND SOUTH AND EAST OF KPHL DUE TO A
WEAKENING SEA BREEZE.

MONDAY...VFR OVERALL, WITH A CEILING AROUND 5000 FEET EXPECTED.
NORTHWEST WINDS INCREASING TO 10-15 KNOTS WITH GUSTS TO AROUND 20
KNOTS /HIGHEST WINDS MAINLY IN THE AFTERNOON/. A FEW AFTERNOON
SHOWERS SHOULD DEVELOP, HOWEVER THE COVERAGE SHOULD BE ISOLATED TO
PERHAPS SCATTERED.

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 WATERS AND SHOULD
REMAIN SO TONIGHT AND FOR MUCH OF THE DAY MONDAY. THE FLOW IS
ONSHORE THOUGH ACROSS THE SOUTHERN AND CENTRAL WATERS INCLUDING
DELAWARE BAY AS A SEA BREEZE TURNED THE WINDS SOUTHEASTERLY AND
INCREASED THEM A BIT THIS EVENING. THIS SHOULD BECOME MORE
NORTHWESTERLY OVERNIGHT AS THE GRADIENT FLOW TAKES OVER. FOR MONDAY
AFTERNOON, WINDS WILL INCREASE FROM THE NORTHWEST AND SEAS WILL
BEGIN TO BUILD. CONDITIONS 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...GORSE
SHORT TERM...AMC
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...AMC/GORSE/IOVINO
FIRE WEATHER...IOVINO


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