Skip Navigation Linkswww.nws.noaa.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service Forecast Office   NWS logo - Click to go to the NWS homepage
Philadelphia/Mount Holly banner image
 
 

Area Forecast Discussion
Latest Versions  [Current][-1][-2][-3][-4]



000
FXUS61 KPHI 230914 CCA
AFDPHI

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
411 AM EST SUN NOV 23 2014

.SYNOPSIS...
A LOW WILL LIFT FROM THE SOUTHERN PLAINS TO THE EASTERN GREAT LAKES 
REGION TODAY INTO TOMORROW. AS IT DOES SO, FIRST A WARM FRONT WILL 
LIFT THROUGH OUR REGION TONIGHT, THEN A COLD FRONT WILL SWEEP 
THROUGH MONDAY. HIGH PRESSURE FOLLOWS LATER TUESDAY. A COASTAL STORM 
WILL DEVELOP OFF THE CAROLINA COAST WEDNESDAY BEFORE MOVING EAST OF 
NEW ENGLAND BY THANKSGIVING. IN ITS WAKE, A COLD AIR MASS SETTLES IN 
OVER THE OHIO VALLEY AT THE END OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRES WILL MOVE EWD AND OFF THE COAST TODAY.  AS IT DOES, SWLY 
FLOW WILL INCREASE AND EXPECT A MUCH WARMER DAY AS HIGH MAKE IT INTO 
THE 50S OVER MOST OF THE AREA.  CLOUDS WILL ALSO INCREASE BY LATE IN 
THE DAY.  

LOW PRES DEVELOPING OVER THE SRN PLAINS WILL MOVE NEWD DURG THE DAY, 
BUT SHOULD REMAIN FAR ENOUGH WWD TO KEEP ANY PRECIP AWAY FROM THE 
REGION THOUGH THE DAY.

&&

.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 AT LEAST THROUGH THE DAY THURSDAY 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 /08Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY AND SURROUNDING AREAS.

VFR TO START THEN DETERIORATING CONDS THIS EVENING AND TONIGHT.  
HIGH PRES OVER THE REGION WILL MOVE EWD.  AS IT DOES SWLY FLOW WILL 
STRENGTHEN ACRS THE AREA.  LOW PRES WILL ALSO DEVELOP ACRS THE SRN 
PLAINS AND MOVE TO NR THE GRTLKS BY MON MRNG.  THE ASSOCD WMFNT WITH 
THIS LOW WILL CROSS THE REGION TONIGHT AND THE WIND SHUD BECOME MORE 
SELY AND CUD GUST IN THE 15 TO 20 KT RANGE.  RAIN WILL DEVELOP FROM SW TO 
NE DURG THE EVE HOURS AND OVERSPREAD THE ENTIRE AREA, PSBLY BECOMING 
HEAVY AT TIMES OVERNIGHT.  A RUMBLE OF THUNDER CAN NOT BE RULED OUT 
OVER THE DELMARVA OR SERN NJ.  

CONDS ARE EXPECTED TO DETERIORATE TO MVFR AND IFR FROM EVENING 
ONWARD AND SOME LIFR IS PSBL THOUGH CONFIDENCE IS NOT HIGH ENOUGH TO 
FORECAST IT ATTM.  

WITH A STRONG LOW LEVEL JET EXPECTED TO DEVELOP OVERNIGHT, LLWS IS 
PSBL IN THE OVERNIGHT HOURS CONTINUING THRU THE MRNG.

OUTLOOK...
MONDAY...MVFR, AND LOCALIZED IFR CEILINGS, WILL CONTINUE THROUGH
MUCH OF THE DAY ON MONDAY AS THE -RA SLOWLY MOVES OUT. 

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...
THE FOLLOWING CHANGES WERE MADE TO THE MARINE HEADLINES...BASED ON 
THE LATEST OBS, THE SCA THRU THIS MRNG HAS BEEN DROPPED.  ALSO THE 
GALE WATCH FOR TONIGHT HAS BEEN UPGRADED TO A GALE WARNING.  SEAS 
AND WIND 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

&&

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








National Weather Service
Disclaimer Privacy Policy