Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 200140
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
940 PM EDT SUN OCT 19 2014

.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE TO OUR SOUTH TONIGHT. ON MONDAY A
LOW PRESSURE SYSTEM WITH AN ASSOCIATED COLD FRONT WILL DIVE
SOUTHEAST FROM THE UPPER GREAT LAKES REACHING OUR REGION DURING THE
DAY TUESDAY. ANOTHER LOW PRESSURE WILL FORM OFF THE CAROLINA
COASTLINE ON TUESDAY AS WELL. THESE TWO LOW PRESSURE SYSTEMS WILL
INTERACT WITH EACH OTHER AND MERGE JUST OFFSHORE WEDNESDAY AND
THURSDAY. THE LOW PRESSURE SYSTEM WILL DEPART THE REGION BY FRIDAY
WITH HIGH PRESSURE MOVING IN FROM THE WEST BY SATURDAY. THIS WILL BE
FOLLOWED BY A COLD FRONTAL PASSAGE SATURDAY NIGHT. ANOTHER AREA OF
HIGH PRESSURE MOVES IN FROM THE WEST ON SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
NO CHANGES TO THE FROST/FREEZE HEADLINES THIS EVENING. WE WILL
LEAVE THE ADVISORIES/WARNINGS AS THEY ARE AS DEWPOINTS ACROSS MUCH
OF THESE AREAS ARE STILL LOW AT THIS POINT THAT THERE IS STILL
PLENTY OF ROOM FOR TEMPERATURES TO DROP OVERNIGHT. DEWPOINTS HAVE
ACTUALLY RISEN SLIGHTLY WHERE THERE IS NO ADVISORY, AND THERE IS
SOME CLOUD COVER MOVING IN FROM THE WEST. SO WE THINK THIS MAY
KEEP TEMPERATURES SLIGHTLY WARM ENOUGH TO PREVENT WIDESPREAD FROST
AND KEEP IT MORE PATCHY IN THESE AREAS.

WIND GUSTS HAVE DROPPED OFF AND WILL BECOME LIGHT AND
VARIABLE/CALM ACROSS THE AREA. ANY DIRECTION WILL BE MOSTLY
NORTHWEST EARLY, THEN WESTERLY OVERNIGHT.

TEMPERATURES TONIGHT WERE A BLEND OF THE MET/MAVMOS WITH A
HEAVIER WEIGHTING ON THE SLIGHTLY COOLER MET. THE NAM OVERALL
APPEARED TO INITIALIZE BETTER THAN THE GFS UPSTREAM.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
NOT MUCH IN THE WAY OF SENSIBLE WEATHER CHANGE OTHER THAN WE SHOULD
BE ABLE TO TACK ON A FEW DEGREES TO DAYTIME HIGHS. WINDS BACK
TOWARDS THE SOUTH-SOUTHWEST BY LATE MORNING AS HIGH PRESSURE MOVES
OFFSHORE TO OUR SOUTHEAST. DEWPOINTS WILL BEGIN TO CREEP UP THOUGH
NOT ENOUGH TO ALLOW FOR COLUMN SATURATION. WE KEEP MONDAY DRY AHEAD
OF THE NEXT UPPER LEVEL WAVE RIPPLING ACROSS THE OHIO VALLEY.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
MONDAY NIGHT: CLOUDS AND WAA BEGIN TO INCREASE AHEAD OF THE NEXT
COLD FRONTAL SYSTEM. ENOUGH LIFT SHOULD BE PRESENT TO GENERATE SOME
SCATTERED SHOWERS ACROSS WESTERN PARTS OF THE CWA BY SUNRISE TUESDAY
WITH QPF UNDER 1/10TH OF AN INCH. MAV AND MET GUIDANCE SETS USED FOR
MOST WEATHER ELEMENTS IN THIS PERIOD.

TUESDAY THROUGH THURSDAY NIGHT: A COASTAL LOW PRESSURE SYSTEM WILL
DEVELOP OFFSHORE AND BE SLOW TO MOVE NORTHEAST THROUGHOUT THIS
PERIOD. THE END RESULT WILL BE GRAY GLOOMY COOLER DAYS FEATURING
RAIN SHOWERS AND SOME BRISK NORTHWESTERLY WINDS WEDNESDAY AND
THURSDAY AFTERNOONS. THE FORMATION OF THIS LOW PRESSURE WILL START
WITH TWO PIECES, A STRONG UPPER LEVEL LOW AND COLD FRONT DIVING FROM
THE GREAT LAKES INTO THE MID-ATLANTIC AND A LOW PRESSURE FORMING OFF
THE CAROLINA`S. THE UPPER LOW AND COLD FRONTAL BOUNDARY WILL LEAD TO
CONTINUED SCATTERED SHOWERS ON TUESDAY TO THE REGION WITH A MOISTURE
PLUME FROM THE CAROLINA LOW WELL OFFSHORE. BY TUESDAY NIGHT WE BEGIN
TO SEE MORE INTERACTION BETWEEN THE FEATURES, PHASING. A PHASED LOW
FORMS OFF THE SOUTHERN NEW ENGLAND COASTLINE BY WEDNESDAY WITH THE
MAJORITY OF ATLANTIC MOISTURE BROUGHT INTO SOUTHERN NEW ENGLAND. TO
COMPARE OUR REGION WOULD BE FAVORED FOR JUST SOME WRAP AROUND
SHOWERS.

OVERALL THE OPERATIONAL MODELS HAVE COME INTO BETTER CONSENSUS TODAY
THAT THE ABOVE OUTCOME WILL OCCUR. THIS IS REFLECTED IN BOTH THE 00Z
ECMWF ENSEMBLE MEAN COMPARED TO THE OPERATIONAL RUN AND THE 06Z
GEFS. WITH THAT BEING SAID, CONFIDENCE CONTINUES TO INCREASE THAT
THIS PERIOD WILL BE DOMINATED BY SOME SCATTERED SHOWERS LASTING
THROUGH THURSDAY. AREAS FURTHER NORTHEAST CLOSER TO THE LOW
STAND THE BEST CHANCE TO SEE THE MOST IN TERMS OF SHOWER ACTIVITY.
TIMING DIFFERENCES ON THE SHOWERS ARE STILL PRESENT LEAVING SOME
UNCERTAINTY WITH POPS, KEPT AT HIGH CHANCE TO LOW END LIKELY.
TOTAL RAINFALL WILL BE UNDER ONE INCH FOR THIS EVENT. THE 12Z
ECMWF AND NAM FROM TODAY DO INDICATE THE POTENTIAL FOR SOME
HEAVIER SHOWERS ACROSS THE NORTH TUESDAY NIGHT INTO WEDNESDAY AS
THE MID-LEVEL ENERGY BEGINS TO TRANSFER TO THE COAST, THIS WILL
NEED TO BE WATCHED AS NEW DATA COMES IN. WITH PLENTY OF CLOUDS, LOW
TEMPERATURES WILL STAY UP AT NIGHT CLOSE TO 50 FOR MOST OF US
WHILE HIGHS STRUGGLE TOWARD 60, COOLER NW. NOT MUCH SPREAD IN THE
MODELS AND THERE ENSEMBLES/ STATISTICAL GUIDANCE ON TEMPERATURES,
WENT ON THE WARMER END EACH NIGHT AND THE COOLER END DURING EACH
DAY. IN TERMS OF TIDES IT LOOKS AS THOUGH THE WIND DIRECTION WILL
NOT CREATE DEPARTURES HIGH ENOUGH FOR MINOR COASTAL FLOODING OR
CREATE LOW ENOUGH DEPARTURES FOR BLOWOUT TIDES ATTM.


FRIDAY: LOW PRESSURE SYSTEM FINALLY DEPARTS WITH HIGH PRESSURE
BUILDING BACK IN. THIS ALLOWS FOR CLEARING FROM SOUTH TO NORTH AND
THE FIRST DRY DAY IN A WHILE. TEMPERATURES ARE FORECASTED TO BE
CLOSER TO MEX GUIDANCE AND THE 12Z ECMWF MODELED TWO METER
TEMPERATURES. CONTINUED NORTHWEST WINDS WITH THE BEST CHANCE OF
MIXING TO LEAD TO SOME AFTERNOON WIND GUSTS AROUND 20 MPH.

FRIDAY NIGHT THROUGH SUNDAY: DURING D+6 AND D+7, THE NEGATIVE
NAO/POSITIVE PNA PATTERN OF THE PAST TWO WEEKS IS PROJECTED TO
REVERSE. THIS TREND IS UNDERWAY, AND IS EVIDENT IN LESS HIGH-
LATITUDE BLOCKING. THE MAIN MID-LEVEL FEATURES IN THIS TIMEFRAME
ARE A CLOSED LOW LIFTING INTO THE CANADIAN MARITIMES ON SATURDAY,
FOLLOWED BY A SHORT-WAVE MOVING THROUGH A MORE ZONAL FLOW ON
SUNDAY. THERE IS MODEL DISAGREEMENT WITH THESE FEATURES, AS THE
GFS EJECTS THE CLOSED LOW SLOWER THAN THE ECMWF, RESULTING IN A
DELAYED RETURN TO A MORE ZONAL FLOW. THIS FURTHER RESULTS IN THE
GFS MOVING THE SHORTWAVE FURTHER NORTHEAST, WHILE THE ECMWF TAKES
IT MUCH FURTHER TO THE SOUTH OVER NEW ENGLAND. SOME OF THE GFS
ENSEMBLE MEMBERS ALSO SUPPORT THE ECMWF SOLUTION. GIVEN THE GFS
INITIALIZED MORE ROBUST WITH THE LEAD SHORT-WAVE /LOCATED OVER
NORTHERN SASKATCHEWAN AS OF THIS WRITING/ THAT RESULTS IN THE CUT-
OFF LOW, AND PREVIOUS GFS RUNS WERE MORE IN LINE WITH THE ECMWF,
FEEL THE GFS SOLUTION IS UNREALISTIC. THE ECMWF SOLUTION IS ALSO
MORE REPRESENTATIVE OF THE PROJECTED LACK OF HIGH-LATITUDE
BLOCKING.

OR SATURDAY, SHORT-WAVE RIDGING ALOFT WILL ALLOW HIGH PRESSURE
TO BUILD IN FROM THE WEST, WITH TEMPS AT 850 HPA SUPPORTING HIGH
TEMPERATURES AT SEASONABLE LEVELS. A COLD FRONT IS PROJECTED TO MOVE
THROUGH THE REGION SOMETIME IN THE LATE SATURDAY INTO EARLY SUNDAY
TIMEFRAME. AT THIS TIME, THE ECMWF INDICATES THE BEST DYNAMICS
SITUATED TO THE NORTH AND LIMITED MOISTURE, BUT IT IS TOO FAR OUT TO
SPECULATE ON PRECIP CHANCES. IF THE TIMING OF THE FRONT HOLDS,
PROJECTED 850 HPA TEMPS WOULD SUPPORT BELOW NORMAL HIGHS ON SUNDAY.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TONIGHT...VFR WITH ONLY CIRRUS CLOUDS EXPECTED OVERNIGHT. WIND
GUSTS HAVE DROPPED OFF AND WINDS WILL BECOME LIGHT AND
VARIABLE/CALM MOST PLACES OVERNIGHT. ANY DIRECTION WILL SWITCH
FROM MOSTLY NORTHWEST TO WEST OVERNIGHT.

MONDAY...VFR. WINDS BACK TOWARDS THE SOUTH-SOUTHWEST AND INCREASE TO
AROUND 10 KNOTS. INCREASING CIRRUS BECOMING ALTOCU BY EARLY
AFTERNOON. THINK ANY RAIN CHANCES HOLDS OFF UNTIL LATE MONDAY
NIGHT.

OUTLOOK...
MONDAY NIGHT AND TUESDAY...SOME RESTRICTIONS TO MVFR WITH SCATTERED
SHOWERS.

TUESDAY NIGHT THROUGH THURSDAY... SOME MVFR RESTRICTIONS WITH
SCATTERED SHOWERS. NORTH TO NORTHWEST WINDS WEDNESDAY AFTERNOON
THROUGH THURSDAY FROM 10-15 KNOTS WITH HIGHER GUSTS.

THURSDAY NIGHT AND FRIDAY: VFR, NORTHWEST WIND GUSTS FRIDAY
AFTERNOON FROM 15-20 KNOTS.

&&

.MARINE...
TONIGHT...THE SMALL CRAFT ADVISORY ON THE DELAWARE BAY WAS ALLOWED
TO EXPIRE AT 8PM AS GUSTS HAVE DROPPED OFF THERE. THE OCEAN FRONT
REMAINS UNCHANGED FROM THE MIDNIGHT END TIME. HIGH PRESSURE
MOVING IN WILL ALLOW THE WIND AND SEAS TO RELAX LATE TONIGHT.

MONDAY...SUB-SCA CONDITIONS. WINDS BACK TOWARDS THE SOUTH-SOUTHWEST
TOMORROW AFTERNOON AROUND 10 TO 15 KNOTS. SEAS REMAIN 2 TO 3 FEET.

OUTLOOK...
MONDAY NIGHT THROUGH WEDNESDAY: SEAS AND WINDS BELOW SCA CRITERIA
BUT INCREASING WEDNESDAY WITH THE DEVELOPMENT OF A LOW PRESSURE TO
OUR NORTHEAST.

WEDNESDAY NIGHT THROUGH FRIDAY: OVERALL THINKING IS THAT WAVEWATCH
IS UNDERDONE BY ABOUT A FOOT ON THE SEAS. SEAS WILL LIKELY BE AT OR
OVER FIVE FEET THROUGH MOST OF THIS PERIOD WITH SOME DECREASE IN THE
SEAS FRIDAY. NORTHWEST WIND GUSTS OVER 25 KNOTS ARE ALSO POSSIBLE
EACH AFTERNOON. SCA POSSIBLE FOR MOST OF THIS TIMEFRAME.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZE WARNING FROM 3 AM TO 8 AM EDT MONDAY FOR PAZ054-055-061-
     062.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT MONDAY FOR PAZ060-101>106.
NJ...FREEZE WARNING FROM 3 AM TO 8 AM EDT MONDAY FOR NJZ001-007>010.
     FREEZE WARNING FROM 4 AM TO 8 AM EDT MONDAY FOR NJZ020>022-027.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT MONDAY FOR NJZ012-013-
     015>019-023.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ430-431-
     450>455.

&&

$$
SYNOPSIS...FRANCK/GAINES
NEAR TERM...HEAVENER/ROBERTSON
SHORT TERM...HEAVENER
LONG TERM...FRANCK/GAINES
AVIATION...GAINES/HEAVENER/ROBERTSON
MARINE...GAINES/HEAVENER/ROBERTSON




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