Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 231724
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1224 PM EST SUN NOV 23 2014

.SYNOPSIS...
LOW PRESSURE WILL LIFT FROM THE SOUTHERN PLAINS TO THE EASTERN GREAT
LAKES REGION TODAY INTO MONDAY. AS IT DOES, A WARM FRONT WILL LIFT
THROUGH OUR REGION TONIGHT, THEN A COLD FRONT WILL SWEEP THROUGH
LATE MONDAY. HIGH PRESSURE FOLLOWS FOR LATER TUESDAY. A COASTAL STORM
WILL DEVELOP OFF THE CAROLINA COAST WEDNESDAY BEFORE MOVING EAST OF
NEW ENGLAND BY THANKSGIVING. A SECOND COLD FRONT WILL MOVE THROUGH
LATE THURSDAY, THEN HIGH PRESSURE BUILDS IN LATER FRIDAY INTO
SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE CENTERED EAST OF THE MID ATLANTIC COAST IS RESULTING
IN A RETURN FLOW ACROSS THE ENTIRE AREA. AN UPPER-LEVEL TROUGH
CONTINUES TO AMPLIFY FROM THE NORTHERN PLAINS TO THE LOWER
MISSISSIPPI VALLEY, WITH A STRONG SHORT WAVE EVIDENT ON THE WATER
VAPOR IMAGERY OVER LOUISIANA. DOWNSTREAM FROM THIS, A RIDGE IS
BUILDING ACROSS THE EAST.

THE PRESENT OF THIS RIDGE IS HELPING TO DEFLECT LINGERING WEAK LIFT
FARTHER NORTHWARD. THIS IS ALSO WHERE THE LOW-LEVEL JET IS SHIFTING WITH
TIME TODAY. THEREFORE THE ASSOCIATED CLOUD BAND IS LIFTING
NORTHWARD ACROSS OUR FAR NORTHERN ZONES. THERE IS ANOTHER AREA OF
CLOUDINESS WORKING NORTHWARD ACROSS PORTIONS OF THE DELMARVA ZONES
AND INTO FAR SOUTHERN NEW JERSEY, AND THIS IS CIRRUS FROM THE
DEVELOPING SYSTEM ACROSS THE GULF COAST STATES. OVERALL, CLOUDS
INCREASE AGAIN FROM SOUTH TO NORTH BY EVENING.

WE REMAIN UNDER A WAA REGIME THROUGH THIS AFTERNOON WITH A SOUTHERLY
FLOW. THIS WILL RESULT IN A WARMER AFTERNOON, AND HIGH TEMPERATURES
WERE INCREASED SOME ACROSS MANY AREAS. THE HOURLY GRIDS WERE
ADJUSTED BASED ON THE LATEST OBSERVATIONS. THIS INCLUDED A BIT
FASTER INCREASE IN THE TEMPERATURES THROUGH THE NEXT FEW HOURS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
THE AFOREMENTIONED LOW WILL MOVE TOWARD THE GRTLKS TONIGHT AND BRING
ITS ASSOCD WMFNT THRU ERLY AND A MARKED INCREASE IN SWLY FLOW.
THERE WILL ALSO BE AN INCREASE IN MOISTURE AND THE DEVELOPMENT OF A
POTENT LLJ.  OVERNIGHT LOWS TONIGHT WILL NOT DROP MUCH IN RESPONSE
TO THICKENING AND LOWERING CLOUDS AND THE SWLY WIND.   PRECIP CHCS
WILL INCREASE THRU THE NIGHT.  DURG THE EVE THE BEST CHCS WILL BE S
AND W WITH PRECIP EVERYWHERE AND HIGH POPS DURG THE OVERNIGHT AND
ERLY MRNG HOURS.  RAIN COULD BE HVY AT TIMES AND SOME THUNDER CAN
NOT BE RULED OUT ESPECIALLY S AND E.  QPF VALUES WILL GENLY BE
BETWEEN 1/2 AND 3/4 OF AN INCH WITH LOCALLY HIGHER AMOUNTS.  WITH
TEMPS EXPECTED TO BE WELL ABOVE FREEZING EVERYWHERE ALL OF THE PRECIP
THAT FALLS WILL BE IN THE LIQUID FORM.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
BIG STORY IS THE WEDNESDAY COASTAL SYSTEM...BUT BEFORE WE GET
AHEAD OF OURSELVES, THERE ARE A FEW THINGS TO TALK ABOUT FOR
MONDAY.

HARD TO BELIEVE WE COULD GO FROM A RECORD LOW AT ALLENTOWN
YESTERDAY TO NEAR RECORD HIGHS JUST TWO DAYS LATER, BUT THAT IS
WHAT IS LOOKING LIKE IN THE WAKE OF THE WARM FRONT. AS MENTIONED
IN THE SHORT TERM SECTION, THERE IS A HIGH CHANCE OF RAIN EARLY IN
THE DAY. ALSO, AFTER SUNRISE, THERE LOOKS TO BE SOME ELEVATED
INSTABILITY ABOVE THE STABLE MARINE LAYER ESPECIALLY NEAR THE
COASTS IN DE AND SOUTHERN NJ. THUS, CONTINUE WITH MENTION OF
THUNDER. RAIN SHOULD MOVE OUT BY THE LATE AFTERNOON/EARLY EVENING
HOURS, WELL AHEAD OF THE ARRIVAL OF THE COLD FRONT.

THERE IS GOOD MODEL AGREEMENT ON THE TIMING OF THE COLD
FRONT...MOVING THROUGH THE REGION DURING THE OVERNIGHT HOURS MONDAY
NIGHT. THEN TUESDAY LOOKS LIKE A PLEASANT DAY. TEMPERATURES WILL
BE 15 TO 20 DEGREES LOWER AS COMPARED TO MONDAY, BUT NEAR NORMALS.

WEDNESDAY AND WEDNESDAY NIGHT...THE PERIOD EVERYONE IS TALKING
ABOUT. STILL LOOKING AT A COASTAL SYSTEM DEVELOPING OFF THE
CAROLINA COAST EARLY ON WEDNESDAY THEN LIFTING NORTHEAST, AND WILL
BE EAST OF NEW ENGLAND BY THURSDAY. THERE ARE STILL SOME MODEL
DIFFERENCES MOST NOTABLY WITH THE TRACK OF THE SURFACE LOW,
THOUGH THE GAP IS CLOSING BETWEEN THE ECMWF TRACK (STILL THE
FURTHEST WEST) AND THE CMC TRACK (STILL THE FURTHEST EAST), WITH
THE GFS IN A COMFORTABLE MIDDLE GROUND. AS FAR AS PRECIP CHANCES,
IT LOOKS VERY LIKELY THAT AREAS EAST AND SOUTH OF THE I95 CORRIDOR
WILL SEE PRECIPITATION DURING THE DAY WEDNESDAY INTO WEDNESDAY
EVENING. FOR AREAS NORTH AND WEST OF THE I95 CORRIDOR, THE CHANCE
IS LESS, THOUGH STILL QUITE HIGH THAT THERE WILL BE WIDESPREAD
PRECIP THROUGH WEDNESDAY NIGHT AS EVEN THE MIDDLE OF THE ROAD GFS
SOLUTION SHOWS THE PRECIP EXTENDING WEST OF THE POCONOS.

PRECIP TYPE IS CONSIDERABLY MORE UNCERTAIN. THE ECMWF DEPICTS A
MID LEVEL SOUTHWESTERLY JET OVER THE EASTERN HALF OF THE REGION,
PRODUCING A ROBUST WARM LAYER WHICH WOULD MEAN VERY FEW ICE
CRYSTALS ALOFT. HOWEVER, WITH THE EXCEPTION OF THE HIGHER TERRAIN
OF THE POCONOS, THE ECMWF KEEPS SURFACE TEMPERATURES WELL ABOVE
FREEZING, SO JUST A COLD RAIN FOR MOST OF THE REGION WHILE THERE
IS A SLIM CHANCE OF FREEZING PRECIP IN THE HIGHER TERRAIN OF THE
POCONOS. THE GFS ON THE OTHER HAND, HAS THE JET, AND CONSEQUENTLY
MID LEVEL WARM AIR ADVECTION OVER THE OCEAN, RESULTING IN EITHER
ALL RAIN OR A RAIN/SNOW MIX FOR MOST OF THE AREA, WITH ALL SNOW
POSSIBLE IN THE POCONOS. WITH EITHER SOLUTION, THE CHANCES OF
SIGNIFICANT ACCUMULATING SNOW DURING THE DAY SEEM SMALL (WITH THE
EXCEPTION OF THE POCONOS).

WHAT COULD BE THE BIGGER ISSUE IS IF OR HOW LONG THE PRECIP LINGERS
THROUGH THE NIGHT TIME HOURS WEDNESDAY NIGHT. THE GFS HAS PRECIP
RAPIDLY MOVING OUT BY MIDNIGHT WEDNESDAY NIGHT. WITH THIS
SOLUTION, WHILE MUCH OF THE REGION COULD SEE A PERIOD OF ALL SNOW
AFTER SUNSET, THE WINDOW OF OPPORTUNITY FOR ACCUMULATING SNOW
WOULD BE BRIEF. THE ECMWF ON THE OTHER HAND, LINGERS PRECIP IN THE
REGION THROUGH THURSDAY MORNING, BUT KEEPS THE EASTERN HALF THE
REGION ABOVE FREEZING THROUGH THE NIGHT. ALL THAT TO SAY THAT
WHILE PRECIPITATION LOOKS VERY LIKELY IN THE WEDNESDAY TO
WEDNESDAY NIGHT PERIOD, THE CHANCE FOR SIGNIFICANT ACCUMULATING
SNOW FOR MOST OF THE REGION IS QUITE SMALL.

ONCE THE PRECIP CLEARS OUT, THANKSGIVING LOOKS TO BE PLEASANT,
ALBEIT CHILLY WITH HIGHS ABOUT 10 DEGREES BELOW NORMAL. IN THE
WAKE OF THE COASTAL LOW, A CONTINENTAL POLAR AIR MASS SETTLES IN
OVER THE REGION FOR THE REMAINDER OF THE WEEK KEEPING HIGHS IN THE
30S AND 40S.

&&

.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR, WITH CEILINGS AT OR ABOVE 10,000 FEET.
SOUTHWESTERLY WINDS 10 KNOTS OR LESS, BECOMING SOUTHEASTERLY
TOWARD EVENING.

TONIGHT...VFR TO START, THEN CEILINGS ARE EXPECTED TO QUICKLY LOWER
TO MVFR AND IFR /LOCAL LIFR/ AS A WARM FRONT ARRIVES. A PERIOD OF
RAIN IS EXPECTED TO MOVE THROUGH, SOME OF WHICH COULD BE HEAVY AT
TIMES. THIS WILL ALSO REDUCE THE VISIBILITIES, WITH EVEN SOME FOG
POSSIBLE LATE ESPECIALLY TOWARD THE COAST AND FROM NEAR KABE ON
NORTHWARD. SOUTH TO SOUTHEAST WINDS AT 5-10 KNOTS WILL INCREASE TO
NEAR 15 KNOTS OVERNIGHT AND COULD BECOME GUSTY AT TIMES. THE
STRONGEST WINDS SHOULD BE FROM NEAR THE KPHL METRO ON SOUTH AND
EAST. AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT LATE SOUTH AND
EAST OF KPHL. A POTENT LOW-LEVEL JET MOVES ACROSS THE AREA, AND
THEREFORE LOW-LEVEL WIND SHEAR WAS INCLUDED FOR THE OVERNIGHT.

MONDAY...IFR /LOCAL LIFR/ CEILINGS FOR AWHILE IN THE MORNING, THEN
CEILINGS SHOULD RISE TO MVFR AND THEN PERHAPS VFR IN THE AFTERNOON
AS A MUCH WARMER AIRMASS IS IN PLACE. IT IS POSSIBLE THOUGH THAT
SOME LOW CLOUDS LINGER LONGER ESPECIALLY CLOSER TO THE COAST. RAIN
DEPARTS EARLY, HOWEVER A FEW SHOWERS THROUGH THE DAY WILL BE
POSSIBLE. SOUTHWESTERLY WINDS 15-20 KNOTS WITH GUSTS UP TO 30 KNOTS.
THE CORE OF LOW-LEVEL JET SHIFTS FARTHER OFFSHORE DURING THE DAY,
THEREFORE LOW-LEVEL WIND SHEAR SHOULD DECREASE DURING THE MORNING.

OUTLOOK...
MONDAY NIGHT INTO TUESDAY...CONDITIONS SHOULD RETURN TO VFR
THROUGH THIS PERIOD.

WEDNESDAY...A COASTAL STORM WILL LIKELY BRING MVFR OR IFR CEILINGS
AND REDUCED VISIBILITIES DUE TO RA (POSSIBLY RASN AT TIMES) FOR
THE REGION. IN ADDITION, EXPECT PERSISTENT NORTHERLY OR
NORTHEASTERLY WINDS FOR GENERALLY THE LATTER HALF OF THE DAY.

WEDNESDAY NIGHT...MVFR AND IFR CEILINGS CONTINUE. IN ADDITION, IF
PRECIPITATION LINGERS FOR MUCH OF THE NIGHT, COULD SEE -SN AND
REDUCED VISIBILITIES BECAUSE OF IT.

THANKSGIVING...CONDITIONS SLOWLY RETURN TO VFR AND WINDS SHIFT TO
WESTERLY.

&&

.MARINE...
GALE WARNING IN EFFECT FROM MIDNIGHT TONIGHT THROUGH MONDAY
MORNING. SEAS AND WINDS ARE EXPECTED TO INCREASE IN ADVANCE OF LOW
PRESSURE MOVG FROM THE SRN PLAINS TO THE GRTLKS. THE ASSOCD WMFNT
WILL MOVE THRU TONIGHT AND RAIN WILL OVERSPREAD THE WATERS
TONIGHT.

OUTLOOK...
MONDAY...GALE CONDITIONS LOOK TO CONTINUE FOR GENERALLY THE FIRST
HALF OF THE DAY. THEN WINDS AND SEAS WILL BE SLOW TO DECREASE
BELOW SCA CRITERIA.

TUESDAY...CONDITIONS SHOULD FALL BELOW SCA CRITERIA.

WEDNESDAY...WINDS AND SEAS INCREASE IN THE LATER HALF OF THE DAY
ABOVE SCA CRITERIA.

THANKSGIVING...WINDS AND SEAS ARE EXPECTED TO FALL BELOW SCA
CRITERIA EARLY IN THE DAY AND REMAIN BELOW CRITERIA THROUGH THE
REST OF THE DAY.

&&

.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

WITH THE POSSIBILITY OF A MIDWEEK COASTAL STORM BRINGING SNOW TO THE
REGION, WE HAVE INCLUDED DAILY SNOWFALL RECORDS BELOW FOR OUR FOUR
PRIMARY CLIMATE SITES THAT HAVE A LONG-STANDING UNBROKEN PERIOD OF
RECORD (POR) WITH RESPECT TO HISTORICAL SNOWFALL DATA.

DAILY SNOWFALL RECORDS:

NOVEMBER 26TH:               NOVEMBER 27TH:       PERIOD OF RECORD:

ACY: TRACE 1977,1957,1955    1.2 INCHES 1978            1874

PHL: 6.0 INCHES 1898         6.9 INCHES 1949,1938       1872

ILG: 0.1 INCHES 1950         4.5 INCHES 1978            1894

ABE: 1.7 INCHES 1925         7.0 INCHES 1938            1922

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING FROM MIDNIGHT TONIGHT TO 11 AM EST MONDAY FOR
     ANZ430-431-450>455.

&&

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



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