800  
FXUS61 KPHI 221427  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
927 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 1036 MB HIGH PRESSURE SYSTEM CENTERED OVER EASTERN NORTH CAROLINA  
WILL SLOWLY SHIFT EASTWARD THROUGH THIS AFTERNOON. THIS ALONG WITH A  
CLEAR SKY, LOW DEW POINTS AND NO WIND RESULTED IN A VERY COLD START  
TO THE DAY. THE WATER VAPOR IMAGERY SHOWS A SHORT WAVE FROM THE  
GREAT LAKES TO THE 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 PRONOUNCED  
INVERSION. THE WAA AND SOME ISENTROPIC LIFT IS FORECAST TO OCCUR  
WITH THIS BEST NOTED NEAR OUR FAR NORTHWEST ZONES LATE THIS  
AFTERNOON. SOME GUIDANCE TRIES 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 ARE BASICALLY 30 PERCENT OR LESS  
FOR A TIME FOR PORTIONS OF THE POCONOS CENTERED AROUND 00Z. THIS  
IS LOW AND CONFIDENCE IN MUCH IF ANY PRECIPITATION REACHING THE  
GROUND IS LOW. THEREFORE, WE KEPT SOME LOW POPS GOING TOWARD EARLY  
EVENING AND WILL MAINTAIN A MENTION IN THE HAZARDOUS WEATHER  
OUTLOOK.  
 
OTHERWISE, SOME MOSTLY HIGH LEVEL CLOUDS AS THE FLOW STARTS TO BACK  
MORE TO THE SOUTHWEST. 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, AS  
SOME BETTER MIXING THIS AFTERNOON SHOULD HELP BOOST TEMPERATURES.  
 

 
   
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 /15Z SATURDAY THROUGH WEDNESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
REST OF TODAY...VFR, ALTHOUGH SOME MID TO MAINLY HIGH CLOUDS ARE  
ANTICIPATED. LIGHT AND VARIABLE OR CALM WINDS, BECOMING  
SOUTHWESTERLY AND INCREASING TO AROUND 10 KNOTS. THERE CAN BE SOME  
GUSTS TO AROUND 18 KNOTS THIS AFTERNOON.  
 
TONIGHT...VFR, WITH AREAS OF CEILINGS MAINLY AT OR ABOVE 8,000 FEET.  
ANY VERY LIGHT RAIN OR FREEZING RAIN SHOULD STAY NORTH AND WEST OF  
KABE. SOUTHWESTERLY WINDS DIMINISHING TO 5 KNOTS OR LESS.  
 
OUTLOOK...  
SUN...VFR, WITH INCREASING AND LOWERING CLOUDS BY EVENING.  
HIGH CONFIDENCE.  
 
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
 
 
WINDS AND SEAS WILL INCREASE AROUND MID DAY TODAY AS THE HIGH  
SHIFTS FURTHER SOUTHEAST. WIND GUSTS OF 25 TO 30 KT WILL BE  
POSSIBLE ON THE ATLANTIC COASTAL WATERS THIS AFTERNOON THROUGH  
VERY EARLY SUNDAY MORNING. WAVE HEIGHTS UP TO 5 FT ARE EXPECTED IN  
THE ATLANTIC, AND MAY BE SLOWER TO DECREASE SUNDAY MORNING. FOR  
NOW HAVE ISSUED THE SMALL CRAFT ADVISORY FROM NOON TODAY THROUGH 6  
AM SUNDAY MORNING.  
 
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...JOHNSON/NIERENBERG  
CLIMATE...DRAG/KLINE  
 
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