821  
FXUS61 KPHI 100149  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
849 PM EST SUN DEC 9 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE ACROSS THE AREA THIS EVENING WILL WEAKEN OVERNIGHT.  
LOW PRESSURE ACROSS THE CAROLINAS EARLY TONIGHT WILL MOVE NORTHEAST  
TONIGHT WELL EAST OF THE COASTAL WATERS. OVERALL, HIGH PRESSURE  
WILL BUILD IN FOR THE UPCOMING WEEK, BUT COLD FRONT WILL CROSS THE  
REGION WEDNESDAY. A LOW PRESSURE SYSTEM WILL BRING WARMER WEATHER  
BUT ALSO RAIN FOR LATER FRIDAY AND INTO NEXT WEEKEND.  

 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
 
 
845 PM UPDATE...SOME GENERALLY LIGHT PRECIPITATION CONTINUES TO  
FALL OVER PORTIONS OF EASTERN MARYLAND AND SOUTHERN DELAWARE.  
WE'VE HAD REPORTS OF UPWARDS OF AN INCH OR SO OF SNOW OVER  
SUSSEX CO. DELAWARE BUT WITHIN THE PAST HOUR OR SO THE LATEST  
OBS SHOW THIS BECOMING MORE MIXED WITH OR CHANGING TO RAIN AS  
TEMPERATURES ARE WARMING ALOFT AND SURFACE TEMPS REMAIN ABOVE  
FREEZING. THERE WILL CONTINUE TO BE SOME LIGHT RAIN/SNOW MIXED  
AROUND THE NEXT 2-3 HOURS BEFORE PRECIP PUSHES SOUTH OVERNIGHT.  
LITTLE TO NO ADDITIONAL SNOW ACCUMULATION IS EXPECTED.  
 
330 PM...THE HIGH PRESSURE THAT HAS BEEN IN PLACE ACROSS  
EASTERN PENNSYLVANIA AND NEW JERSEY THROUGH TODAY IS CONTINUING  
TO GET SQUEEZED OUT BETWEEN AN AREA OF LOW PRESSURE TO OUR NORTH  
ACROSS EASTERN CANADA AND AN AREA OF LOW PRESSURE TO OUR SOUTH  
NEAR THE COASTS OF SOUTH CAROLINA AND NORTH CAROLINA. AS THE  
HIGH CONTINUES TO WEAKEN ITS GRIP ACROSS THE AREA, RAIN AND SNOW  
NORTH OF THE LOW TO OUR SOUTH CONTINUES TO INCH NORTHWARD. ALL  
OF THE MODEL GUIDANCE INDICATES THE PRECIPITATION MAKING ITS WAY  
ACROSS SOUTHERN DELAWARE, SOUTHEASTERN MARYLAND, AND EVEN INTO  
SOUTHERN NEW JERSEY LATE THIS AFTERNOON INTO THE EARLY EVENING.  
THE STRONGEST LIFT/MOISTURE COMBINATION WITHIN THE DENDRITIC  
ZONES REMAINS JUST TO OUR SOUTH, ALTHOUGH THERE WILL BE SOME  
WEAK LIFT MAKING ITS WAY ACROSS OUR AREA. SO THERE WILL BE THE  
POTENTIAL FOR A COUPLE OF HOURS OF A LIGHT ACCUMULATING SNOW  
FALL ACROSS MAINLY SUSSEX COUNTY, DELAWARE AS WELL AS TALBOT  
COUNTY AND CAROLINE COUNTY, MARYLAND. WITHOUT THE STRONG LIFT  
AND WITH SURFACE TEMPERATURES FAIRLY MARGINAL, LOW TO MID 30S AS  
PRECIPITATION FALLS, SIGNIFICANT ACCUMULATIONS ARE EXPECTED TO  
BE LIMITED. GENERALLY AN INCH OR LESS IS EXPECTED ACROSS THE  
AREA, ALTHOUGH SLIGHT HIGHER AMOUNTS ARE POSSIBLE ACROSS THE  
SOUTHERN EDGES OF THESE COUNTIES.  
 
THE LOW WILL SLOWLY DRIFT EASTWARD THROUGH THE OVERNIGHT HOURS. AS  
IT CONTINUES TO PULL EASTWARD, THE REMAINING MOISTURE AND LIFT WILL  
PULL AWAY FROM OUR AREA AS WELL, AND ANY PRECIPITATION IS EXPECTED TO  
END AROUND OR SHORTLY AFTER MIDNIGHT TONIGHT. ONCE PRECIPITATION  
ENDS, SKIES WILL BEGIN TO CLEAR OUT AND TEMPERATURES WILL FALL AS  
WELL.  
 
FOR THE REMAINDER OF THE AREA, NORTHERN DELAWARE AND MARYLAND, MOST  
OF NEW JERSEY AND PENNSYLVANIA, A PRECIPITATION FREE FORECAST IS  
EXPECTED WITH MAINLY MID-HIGH LEVEL CLOUDS LATE THIS AFTERNOON AND  
THIS EVENING. SKIES WILL BEGIN TO CLEAR OUT OVERNIGHT AND  
TEMPERATURES WILL LOWER THROUGH THE NIGHT.  
 

 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/
 
 
ON MONDAY, THE LOW TO OUR SOUTH WILL CONTINUE TO SLOWLY MOVE OUT TO  
SEA, WHILE A BACKDOOR COLD FRONT APPROACHES FROM THE NORTH. THE  
FRONT WILL REMAIN NORTH OF THE AREA AND NOT MAKE IT INTO OUR AREA.  
HIGH PRESSURE BUILDS WELL TO OUR WEST AND TRIES TO NOSE INTO OUR  
AREA, ALTHOUGH WE WILL BE ON ITS FAR EASTERN EDGE. SOME CLOUD COVER  
WILL LIKELY BE IN PLACE ACROSS NORTHEAST PENNSYLVANIA AND NORTHERN  
NEW JERSEY DURING THE DAY, BUT MOST PLACES WILL BE MOSTLY CLOUD  
FREE. NO PRECIPITATION IS EXPECTED ANYWHERE ON MONDAY.  
 
IT WILL BE ANOTHER SEASONABLY COOL DAY WITH TEMPERATURE NEAR  
NORMAL. HOWEVER THERE WILL BE A STEADY NORTHERLY BREEZE AROUND 5-10  
MPH THROUGH THE DAY WHICH MAY MAKE IT FEEL A LITTLE COOLER.  
 

 
   
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
 
 
MONDAY NIGHT THRU FRIDAY...THIS PERIOD WILL FEATURE DRY WEATHER  
ACROSS THE AREA WITH TEMPERATURES THAT WILL BE, FOR THE MOST PART,  
BELOW NORMAL. A WEAK RIDGE OF HIGH PRESSURE WILL BE ACROSS THE  
REGION MONDAY NIGHT AND TUESDAY, BUT THEN A COLD FRONT WILL DROP  
DOWN FROM THE NORTH WEDNESDAY. A STRONGER HIGH WILL ARRIVE FOR  
THURSDAY AND LINGER INTO FRIDAY. NORMAL HIGH TEMPERATURES FOR THIS  
TIME OF YEAR RANGE FROM THE MID 30S ACROSS THE NORTH TO THE MID 40S  
ACROSS PHILADELPHIA AND SOUTHERN NEW JERSEY. READINGS TUE/WED WILL  
BE 4 TO 6 DEGREES BELOW NORMAL, WHILE THU WILL BE NEAR NORMAL. LOWS  
GENERALLY WILL BE IN THE UPPER TEENS/LOW 20S UP NORTH AND  
MID/UPPER 20S ELSEWHERE. THE BELOW NORMAL TEMPERATURES WILL  
BEGIN TO MOVE OUT LATER THIS WEEK AS THE PATTERN ACROSS THE  
COUNTRY ARE CHANGING WHICH WILL FAVOR MILDER TEMPERATURES FOR  
THE MID-DECEMBER PERIOD. THE CPC 6-10 & 8-14 DAY TEMPERATURE  
OUTLOOKS ARE PREDICTING ABOVE NORMAL READINGS.  
 
WET WEATHER ARRIVES LATER FRIDAY AND REMAINS INTO THE FIRST PART OF  
THE WEEKEND WITH A LOW PRESSURE SPINNING UP ACROSS THE LOWER MISSISSIPPI  
VALLEY FRI AND MOVING NE ACROSS THE MIDDLE ATLANTIC FOR FRI NIGHT  
AND SAT. THE LATEST MODELS ARE STILL RATHER DIFFERENT WITH THE TRACK  
AND INTENSITY. THE 12Z GFS AND CMC MODELS ARE TRACKING THE MODERATE  
INTENSITY LOW WEST OF OUR AREA WITH THE EC MORE ALONG THE  
COAST. EVEN WITH THE EAST TRACK, MODELS ARE ALL RATHER WARM AND  
RAIN IS INDICATED FOR THE AREA. TOTAL QPF COULD BE IN THE 1 TO 2  
INCH RANGE. WE'LL SEE THROUGH THE WEEK WHAT EFFECT THIS MAY  
HAVE ON AREAS RIVERS WITH THE RECENT WET SPELL.  
 
TEMPERATURES FOR FRIDAY AND THE WEEKEND WILL BE ABOVE NORMAL WITH  
HIGHS IN THE 50S IN MOST AREAS (SOME 40S STILL ACROSS THE NORTH).  
DEPENDING ON THE STORM TRACK, MUCH ABOVE NORMAL TEMPS ARE  
POSSIBLE (UPPER 50S/LOW 60S) THIS IS BEING SHOWN IN THE RECENT  
MEX GUIDANCE FOR PHL.  
 

 
   
AVIATION /02Z MONDAY THROUGH FRIDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
TONIGHT...VFR CONDITIONS CONTINUE. MOSTLY LIGHT AND VARIABLE WINDS  
5 KNOTS OR LESS.  
 
MONDAY...SOME MVFR CIGS MAY DEVELOP AROUND OR SHORTLY AFTER DAYBREAK  
FOR ABE AND RDG. OTHERWISE, VFR CONDITIONS WILL CONTINUE THROUGH THE  
DAY. WINDS WILL BECOME NORTHERLY EVERYWHERE (BETWEEN 340-020) WITH  
SPEED 5-10 KNOTS FOR MOST PLACES.  
 
OUTLOOK...  
 
MONDAY NIGHT THRU THURSDAY NIGHT...VFR EXPECTED.  
FRIDAY...LOWERING CIGS WITH RAIN EXPECTED, MOSTLY LATE.  
 

 
   
MARINE
 
 
A SMALL CRAFT ADVISORY REMAINS FOR THE ATLANTIC COASTAL WATERS  
ADJACENT TO CAPE MAY NEW JERSEY AND DELAWARE, AS WELL AS LOWER  
PORTIONS DELAWARE BAY. WIND GUSTS ARE EXPECTED TO INCREASE TO 25  
KNOTS THIS EVENING AND CONTINUE OVERNIGHT. WE EXTENDED THE ADVISORY  
ON THE ATLANTIC OCEAN THROUGH MONDAY AS SEAS WILL BUILD TO NEAR 5-6  
FEET THROUGH THE DAY MONDAY. HOWEVER, WINDS ON LOWER DELAWARE BAY  
WILL LOWER BELOW 25 KNOTS BY DAYBREAK MONDAY, SO IT'S EXPIRATION  
REMAINS THE SAME.  
 
WINDS FOR THE REMAINDER OF THE WATERS IS EXPECTED TO REMAIN BELOW 25  
KNOTS AND SEAS ARE EXPECTED TO REMAIN BELOW 5 FEET, ALTHOUGH WIND  
GUSTS AROUND 20 KNOTS WILL REMAIN POSSIBLE.  
 
OUTLOOK...  
SUB-SCA GENERALLY EXPECTED THROUGH THURSDAY NIGHT BUT SOME NEAR  
SCA GUSTS POSSIBLE TUE NIGHT/WED. LOW CONFID ATTM. SCA CONDITIONS  
EXPECTED TO DEVELOP FRIDAY WITH RAIN MOVING ACROSS THE WATERS.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ431.  
SMALL CRAFT ADVISORY UNTIL 6 PM EST MONDAY FOR ANZ453>455.  
 

 
 

 
SYNOPSIS...O'HARA  
NEAR TERM...FITZSIMMONS/ROBERTSON  
SHORT TERM...ROBERTSON  
LONG TERM...O'HARA  
AVIATION...FITZSIMMONS/ROBERTSON/O'HARA  
MARINE...ROBERTSON/O'HARA  
 
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