441  
FXUS61 KPHI 080544  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
1244 AM EST THU DEC 8 2016  
   
SYNOPSIS
 
 
LOW PRESSURE IN SOUTHEASTERN CANADA WILL MOVE SLOWLY EASTWARD  
THROUGH THE END OF THE WEEK. THE STRONG COLD FRONT ASSOCIATED WITH  
THIS LOW WILL CROSS THE AREA ON THURSDAY. LARGE HIGH PRESSURE WILL  
THEN BUILD IN FOR THE EARLY PART OF THE WEEKEND. THEN, ANOTHER  
AREA OF LOW PRESSURE WILL BEGIN TO BRING PRECIPITATION POSSIBLY AS  
EARLY AS SUNDAY AFTERNOON OR SUNDAY NIGHT, WITH A COLD FRONT  
CROSSING THE REGION MONDAY NIGHT OR EARLY TUESDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
CEILINGS AROUND 10000 TO 15000 FT PERSIST ACROSS THE REGION.  
DESPITE THIS, PATCHY FOG HAS DEVELOPED ACROSS MAINLY PORTIONS OF  
NEW JERSEY. DRY AIR ADVECTION IS A BIT SLOWER THAN PREVIOUSLY  
ANTICIPATED, BUT SOME IS STILL EXPECTED OVERNIGHT. GIVEN THE  
PERSISTENT CLOUD COVER AND RELATIVELY SMALL DEW POINT DEPRESSIONS,  
LOWS SHOULD BE CLOSE TO CURRENT TEMPERATURES.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/
 
 
CONSIDERABLE MID AND HIGH CLOUDINESS DURING THE MORNING BECOMING MOSTLY  
SUNNY AND BREEZY DURING THE AFTERNOON WITH WESTERLY WIND GUSTS EXPECTED  
TO INCREASE TO 25 MPH. THIS CLOUD/WIND SEQUENCE IN ASSN WITH THE  
ARRIVAL IN THE AFTN OF A NE-SW POSITIVE TILT 500 MB TROUGH AXIS  
WITH 12 HR 100-140M HFC OVERHEAD. MAX TEMPS NEAR NORMAL.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
 
 
A STRONG COLD FRONT WILL HAVE CROSSED THE AREA ON THU AND HIGH  
PRES WILL BE BUILDING IN BEHIND IN. STRONG NWLY FLOW WILL RESULT  
FRI INTO SAT, MAKING IT FEEL COLDER.  
 
IN THE NWLY FLOW, THERE CUD BE SOME SNOW SHWRS MAINLY N ON FRI,  
BUT OTHERWISE DRY WX IS EXPECTED THRU SUN.  
 
THE AFOREMENTIONED HIGH PRES WILL MOVE OFF THE COAST DURG SUN AND  
LOW PRES WILL THEN BEGIN TO ADVANCE TWD OUR REGION FROM THE W.  
THERE ARE MDL DIFFS WITH THIS SYS. THE GFS DEVELOPS A LOW ACRS IA  
AND MOVES IT EWD ACRS THE GRTLKS AND INTO SRN CANADA. THE WMFNT  
ASSOCD WITH THIS LOW WILL BRING PRECIP TO THE AREA BEGINNING SUN  
AFTN, WITH THE CDFNT MON MRNG.  
 
THE ECMWF DEVELOPS A MUCH STRONGER LOW OVER THE SRN PLAINS, AND  
MOVES IT NEWD INT THE OH VLY. BY MON AM. DUE TO THE STRONGER LOW,  
IT IS SLOWER WITH ITS MOTION AND THE ONSET AND ENDING TIME OF  
PRECIP. THE ECMWF DOESN'T BRING MUCH PRECIP BEFORE SUN NIGHT, WITH  
THE BULK OF THE PRECIP ON MON BEFORE CFP LATE MON.  
 
THE CMC SOLN IS SOMEWHERE IN THE MIDDLE. SO, WHILE CONFIDENCE IS  
LOWER THAN AVERAGE ON THE ACTUAL TIMING, WE DO KNOW THAT PRECIP  
WILL DEVELOP DURING THE LATTER HALF OF SUNDAY AND CONTINUE FOR AT  
LEAST THE FIRST PORTION OF MONDAY.  
 
OVER NORTHERN AND WRN AREAS, TEMPS WILL BE COLD ENOUGH FOR AT  
LEAST SOME WINTRY PRECIP, SOME OF THAT WILL BE DEPENDENT ON THE  
TRACK OF THE LOW. THE ECMWF IS ALSO A SIGNIFICANTLY WARMER SOLN.  
MOST OTHER AREAS WILL SE ALL OR MOSTLY RAIN, BUT THE DETAILS ON  
THIS ONE WILL NEED TO BE IRONED OUT AS WE GET CLOSER.  
 
HIGH PRES RETURNS FOR TUE. TEMPS LOOK TO BE BELOW NRML THRU MOST,  
IF NOT ALL OF THE PD. THEY CUD RETURN TO CLOSE TO NRML AROUND  
MONDAY, BEFORE DROPPING AGAIN WITH THE NEXT CFP.  
 

 
   
AVIATION /06Z THURSDAY THROUGH MONDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
MOSTLY VFR CONDITIONS ARE EXPECTED OVERNIGHT, BUT PATCHY GROUND  
FOG WILL LEAD LEAD TO TEMPORARY VISIBILITY RESTRICTIONS,  
ESPECIALLY AT KMIV, KPNE, AND KTTN. HAVE SEEN IFR CONDITIONS AT  
KMIV, BUT FOR THE MOST PART DO NOT EXPECT VISIBILITIES BELOW  
MVFR.  
 
THURSDAY...VFR CONDITIONS ARE EXPECTED THROUGH THE DAY, THOUGH MID  
LEVEL CLOUDS COULD RESULT IN CEILINGS AROUND 7000 TO 9000 FT AGL.  
NORTHWESTERLY WINDS WILL INCREASE BY MID DAY WITH GUSTS UP TO 20KT  
POSSIBLE.  
 
OUTLOOK...  
 
THU NIGHT-SAT...MAINLY VFR, BUT SOME LOCAL MVFR POSSIBLE EACH  
MRNG. NW WIND COULD GUST UP TO 25 KTS ON FRI. MODERATE TO HIGH  
CONFIDENCE.  
 
SUN AND MON...VFR EARLY, LOWERING TO MVFR THEN IFR BY THE  
AFTERNOON AND OVERNIGHT. RA AND SN PSBL SUN INTO MON. LOW TO  
MODERATE CONFIDENCE ON THE TIMING OF PRECIP.  
 

 
   
MARINE
 
 
SCA SEAS HAS BEEN EXTENDED SINCE EASTERLY SWELLS IN THE WAKE OF  
LAST NIGHTS SHORT GALE ARE SLOW TO DECREASE. GUIDANCE CONTINUES TO  
LOWER THESE SWELLS/SEAS TOO FAST. PLS SEE MWW OR THE CWF.  
 
EVENTUALLY THE SEAS SHOULD SUBSIDE BELOW THE 5 FT SCA CRITERIA  
OVERNIGHT.  
 
THURSDAY...ANTICIPATING THE NEED FOR A WESTERLY FLOW COLD AIR ADVECTION  
SMALL CRAFT ADVISORY FOR MANY OF THE WATERS THURSDAY AFTERNOON.  
HAVE BEGUN THE PROCESS WITH A DE BAY SCA.  
 
OUTLOOK...  
THU NIGHT-SAT...SCA CONDS EXPECTED IN STRONG NWLY FLOW WITH WIND  
GUSTS UP TO 30 KT. THERE IS A SMALL CHANCE OF GALES THU NIGHT  
INTO FRI BEHIND THE FRONT.  
 
SAT NIGHT-SUN...SUB-SCA CONDS ARE EXPECTED, BUT WIND WILL INCREASE  
TO JUST BELOW SCA BY LATER SUN.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 7 AM EST FRIDAY FOR  
ANZ430-431.  
 

 
 

 
SYNOPSIS...NIERENBERG  
NEAR TERM...DRAG/GAINES/JOHNSON  
SHORT TERM...DRAG  
LONG TERM...NIERENBERG  
AVIATION...DRAG/GAINES/JOHNSON/NIERENBERG  
MARINE...DRAG/GAINES/JOHNSON/NIERENBERG  
 
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