Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 221640
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1140 AM EST SAT NOV 22 2014

.SYNOPSIS...
STRONG HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL GRADUALLY
SHIFT OFFSHORE THROUGH TONIGHT. LOW PRESSURE DEVELOPING OVER THE
SOUTHERN PLAINS WILL MOVE NORTHEASTWARD SUNDAY, PULLING A WARM FRONT
THROUGH OUR REGION SUNDAY NIGHT INTO MONDAY. THE LOW WILL BE NEAR
THE GREAT LAKES TOWARD MONDAY MORNING, AND AS IT MOVES INTO EASTERN
CANADA BY TUESDAY ITS ASSOCIATED COLD FRONT WILL CROSS OUR AREA.
HIGH PRESSURE WILL BUILD IN MONDAY NIGHT AND TUESDAY, THEN AN AREA
OF LOW PRESSURE MAY DEVELOP OFF THE MID ATLANTIC COAST WEDNESDAY
INTO THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A 1035 MB SURFACE HIGH PRESSURE SYSTEM CENTERED OVER EASTERN NORTH
CAROLINA WILL SLOWLY SHIFT EASTWARD THROUGH THIS AFTERNOON. THE
WATER VAPOR IMAGERY SHOWS A SHORT WAVE FROM THE EASTERN GREAT LAKES
TO THE UPPER OHIO VALLEY LIFTING NORTHEASTWARD.

SOME INCREASE IN THE WAA IS OCCURRING TODAY ESPECIALLY ALOFT, AND
THIS IS EVIDENT IN THE 12Z STERLING, VA RAOB WITH A WARM LAYER
CENTERED JUST ABOVE 900 MB. THE WAA AND SOME ISENTROPIC LIFT IS
FORECAST TO OCCUR, WITH THIS BEST NOTED NEAR OUR FAR NORTHWEST ZONES
LATER THIS AFTERNOON. SOME GUIDANCE HAS BEEN TRYING TO BRING SOME
LIGHT QPF INTO PORTIONS OF THE POCONOS LATE THIS AFTERNOON. THE
FORECAST SOUNDINGS SHOW THAT WITH THE WAA, THE PRECIPITATION TYPE
WOULD BE EITHER RAIN, FREEZING RAIN OR PERHAPS A FEW ICE PELLETS.
THESE SOUNDINGS ALSO SHOW A PRONOUNCED DRY LAYER IN THE LOWEST
LEVELS, WHICH COULD ALSO SUGGEST THAT IT COULD BE VIRGA. THE SREF
PROBABILITIES FOR FREEZING RAIN HAVE BASICALLY BEEN 30 PERCENT OR
LESS FOR A TIME FOR PORTIONS OF THE POCONOS CENTERED AROUND 00Z.
THIS IS LOW AND AND IT APPEARS LITTLE IF ANY PRECIPITATION REACHES
THE GROUND. THEREFORE, WE WENT WITH A DRY FORECAST DURING THE
DAYTIME HOURS.

OTHERWISE, SOME CLOUDS WILL INCREASE BY LATER THIS AFTERNOON
ESPECIALLY ACROSS THE WESTERN ZONES CLOSER TO THE SHORT WAVE, WAA
AND LOW-LEVEL JET PUSH. AS THE BOUNDARY LAYER WARMS, BETTER MIXING
IS OCCURRING AND THEREFORE SOME GUSTINESS IN THE WINDS CAN BE
EXPECTED BEFORE THESE DROP OFF TOWARD EVENING. THE HOURLY
TEMPERATURES WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, THEN
THE LAMP/LAV GUIDANCE WAS BLENDED IN. NO MAJOR CHANGES WERE MADE TO
THE HIGH TEMPERATURES ATTM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
A MID LEVEL SHORT WAVE TROUGH MOVES OVER THE NORTHEASTERN U.S.,
AND BOTH THE GFS AND NAM SHOW THE BEST SYNOPTIC LIFT (AS
EVIDENCED BY 500 MB Q VECTOR CONVERGENCE AND POSITIVE PRESSURE
ADVECTION ON THE 1.5 PV SURFACE) STAYING JUST NORTH OF OUR REGION.
HOWEVER, GIVEN HOW CLOSE THE LIFT IS, AND GIVEN THAT THERE COULD
ALSO BE SOME OROGRAPHIC LIFT, HAVE SOME LOW POPS ACROSS THE NORTHWEST
ZONES FOR A TIME. BUT IT STILL SEEMS LIKE AN UNLIKELY EVENT FOR OUR
REGION, SO MOST OF THAT REGION HAS POPS AT OR BELOW 30 PERCENT.

IF THERE IS ANY PRECIPITATION IN OUR AREA, IT WILL BE EITHER IN THE
FORM OF RAIN OR FREEZING RAIN (DEPENDING ON SURFACE TEMPERATURE).
MODEL SOUNDINGS SHOW A ROBUST AND DEEP WARM LAYER. WHILE THERE COULD
BE SOME SEEDER FEEDER CIRRUS CLOUDS PROPAGATING OVERHEAD, WITH THE
MELTING LAYER AROUND 8000 FT MSL, ANY ICE CRYSTALS WOULD MELT
THROUGH THE WARM LAYER. BECAUSE OF THE CONTINUED WARM AIR ADVECTION
EVEN AT THE SURFACE, SEE VERY FEW LOCATIONS DROPPING BELOW FREEZING
BEFORE THE WINDOW OF OPPORTUNITY FOR PRECIPITATION CLOSES. SINCE
TOO, THE CHANCE OF PRECIPITATION IS VERY SMALL AT THIS TIME, WILL
NOT ISSUE A FREEZING RAIN ADVISORY, BUT WILL CONTINUE TO MENTION THE
POTENTIAL IN THE HWO.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
A NICE WARMING TREND IS IN STORE AT THE START OF THE EXTENDED PD AS
HIGH PRES MOVES OFFSHORE AND STRONG SWLY FLOW DEVELOPS OVER THE
AREA.

THEN, LOW PRES WILL TAKE SHAPE OVER THE SRN PLAINS AND BEGIN TO
MOVE NEWD. THE WMFNT ASSOCD WITH THIS LOW WILL MOVE THRU THE
REGION SUN NIGHT AS THE LOW REALLY INTENSIFIES OVER THE MIDSECTION
OF THE NATION. BASED ON THE LATEST GUID MOVG THE PRECIP IN SLOWER,
HAVE REMOVED POPS FROM THE SUNDAY DAYTIME HOURS.  THE BEST WAA IS
SUN NIGHT AND THIS IS THE WETTEST PERIOD WITH RAIN, SOME HEAVY AT
TIMES. WE GET DRY SLOTTED LATER MON AND IN THE WARM SECTOR, TEMPS
WILL SKYROCKET AND COULD REACH RECORD VALUES IN SOME LOCATIONS,
THEN THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT, WITH
ANOTHER CHC OF PRECIP MON EVE BEFORE HIGH PRES BUILD BACK IN FOR
LATER MON NIGHT THRU TUE NIGHT.

THEN, ALL EYES TURN TO THE POTENTIAL FOR A COASTAL LOW DEVELOPING
AROUND WED. MODEL SOLNS ARE ALL OVER THE PLACE AND CONFIDENCE IS
MUCH BELOW AVERAGE ATTM. THE CMC IS WELL OFFSHORE WITH VIRTUALLY
NO IMPACT TO OUR REGION. THE GFS INDICATES THE MOST IMPACT FOR OUR
SRN AND ERN LOCATIONS WED INTO WED NIGHT BEFORE THE LOW PULLS AWAY
ON THANKSGIVING, BRINGING A DRY HOLIDAY. THE ECMWF HAS THE
STRONGEST AND MOST WWD SOLN AND WOULD BRING A MOSTLY WET AND WINDY
PERIOD FROM WED INTO WED NIGHT. IT HAS SOME SUPPORT FROM THE
UKMET. ANY WINTRY PRECIP WOULD BE CONFINED TO NRN AND WRN AREAS
AT THE ONSET AND THE END.

WITH THE POTENTIAL FOR SIGNIFICANT IMPACT DUE TO HOLIDAY TRAVEL
AND ONE OF THE BUSIEST AIR TRAVEL DAYS OF THE YEAR, THIS SYS WILL
CONTINUE TO BE WATCHED AND COULD END UP BEING NOTHING OR SOMETHING
SIGNIFICANT. THE ECMWF MADE A DECENT WWD SHIFT FROM 21/12Z TO
22/00Z, THE GFS DID NOT.

AFTER THIS STORM MOVES BY WHETHER FAR OFFSHORE OR CLOSE TO THE
COAST, ANOTHER WK CDFNT MAY BRING SOME PRECIP ERLY FRI.

TEMPS WILL START OFF FAIRLY WARM ON SUNDAY, REACH THEIR ZENITH ON
MON, WITH NEAR RECORD WARMTH, THEN STILL BE NR NRML ON TUE BEFORE
TAKING A NOSE DIVE THRU THE REMAINDER OF THE WEEK.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR, WITH SOME INCREASE IN CLOUDS ESPECIALLY FOR
THE KABE AND KRDG AREAS. SOUTHWESTERLY WINDS AROUND 10 KNOTS WITH
SOME GUSTS TO AROUND 20 KNOTS.

TONIGHT...VFR, WITH AREAS OF CEILINGS AT OR ABOVE 5,000 FEET.
SOUTHWESTERLY WINDS DIMINISHING TO 5 KNOTS OR LESS.

SUNDAY...VFR, WITH CEILINGS AT TIMES ABOVE 5,000 FEET. SOUTHWEST
WINDS 5-8 KNOTS, BECOMING SOUTHEAST LATE.

OUTLOOK...
SUN NIGHT THROUGH EARLY MON...VERY POOR FLYING CONDS WITH MVFR
EXPECTED AND IFR PSBL IF NOT PROBABLE IN RAIN. RAIN COULD BE HVY
AT TIMES. E TO SE WIND COULD GUST IN THE 20 TO 25 KT RANGE. MDT TO
HIGH CONFIDENCE.

MON AND MON NIGHT...IMPROVING CONDS BUT STILL SOME MVFR PSBL IN
LINGERING SHWRS. CFP/WSFHT MON EVE. VFR BY EVE IF NOT SOONER. LOW
TO MDT CONFIDENCE.

WEDNESDAY...MUCH UNCERTAINTY DEPENDING ON THE TRACK OF A COASTAL
LOW. COULD BE VFR IF LOW IS FAR ENOUGH EAST OR MVFR/IFR IN RAIN
AND WIND IF LOW IS FAR ENOUGH W. BEST CHC FOR VFR IS WRN AIRPORTS.
BEST CHC FOR DEGRADED CONDS IS ERN AIRPORTS. CONFIDENCE VERY LOW.

&&

.MARINE...
THE SOUTHWESTERLY FLOW ON THE BACKSIDE OF HIGH PRESSURE WILL
INCREASE SOME THROUGH THIS AFTERNOON. SOME GUSTS TO 25 KNOTS SHOULD
OCCUR ESPECIALLY ACROSS THE NORTHERN WATERS, HOWEVER IT MAY BE
GENERALLY MARGINAL. THERE SHOULD BE A BETTER CHC OF GUSTS TO AROUND
25 KNOTS TONIGHT ACROSS THE COASTAL WATERS AS THE PRESSURE GRADIENT
TIGHTENS SOME. WAVE HEIGHTS SHOULD RESPOND THROUGH TONIGHT AND BUILD
UP TO 5 FEET IN THE ATLANTIC, AND MAY BE SLOWER TO DECREASE SUNDAY
MORNING. FOR NOW, A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 6 AM
SUNDAY MORNING FOR ALL BUT THE DELAWARE BAY.

OUTLOOK...
SUN...NO MARINE HEADLINES ANTICIPATED.

SUN NIGHT THROUGH MON...SCA CONDS ARE EXPECTED AND GALES ARE PSBL
IF NOT PROBABLE INTO ERLY MON AS STRONG LOW PRES IMPACTS THE
WATERS.

MON NIGHT INTO TUE....BACK END SCA CONDS AS SEAS AND WIND SUBSIDE
SLOWLY.

WED...NO MARINE HEADLINES ANTICIPATED.

&&

.CLIMATE...
FOR OUR EIGHT CLIMATE SITES, HERE ARE THE RECORD HIGH TEMPERATURES
FOR NOVEMBER 24TH AND THE MOST RECENT YEAR OF OCCURRENCE.

RECORD HIGHS 11/24:

ACY:  72  SET IN 1999
PHL:  71  SET IN 1979
ILG:  73  SET IN 1979
ABE:  69  SET IN 1931
TTN:  71  SET IN 1979
GED:  75  SET IN 1992
RDG:  69  SET IN 1979
MPO:  64  SET IN 1931

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...GORSE/NIERENBERG
NEAR TERM...GORSE
SHORT TERM...JOHNSON
LONG TERM...NIERENBERG
AVIATION...GORSE/NIERENBERG
MARINE...GORSE/JOHNSON/NIERENBERG
CLIMATE...DRAG/KLINE




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