874  
FXUS61 KPHI 040715  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
315 AM EDT WED OCT 4 2023  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BECOME MORE CENTERED TO OUR EAST AND NORTHEAST  
THROUGH TONIGHT, HOWEVER IT WILL CONTINUE TO EXTEND ACROSS OUR  
REGION. THE HIGH WEAKENS AND SHIFTS MORE TO OUR NORTHEAST WEDNESDAY  
INTO THURSDAY. A STRONG COLD FRONT MOVES THROUGH ON SATURDAY, WHICH  
BRINGS A COLDER AND MUCH DRIER AIR MASS INTO OUR REGION OVER THE  
WEEKEND THROUGH EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
A CLEAR SKY AND LIGHT WIND ALLOWED AREAS OF FOG TO DEVELOP DURING  
THE NIGHT, MAINLY IN THE VALLEYS OF EASTERN PENNSYLVANIA AND  
NORTHERN NEW JERSEY, AND IN THE PINE BARRENS OF SOUTHERN NEW JERSEY.  
THE FOG IS EXPECTED TO LIFT AND DISSIPATE DURING THE MID MORNING  
HOURS.  
 
HIGH PRESSURE EXTENDED FROM THE SOUTHEASTERN STATES UP INTO NEW  
ENGLAND EARLY THIS MORNING. THE AIR MASS WILL BUILD SLOWLY EASTWARD  
TODAY AND TONIGHT, BRINGING CONTINUED DRY WEATHER TO OUR REGION.  
 
A LIGHT SOUTHERLY WIND IS ANTICIPATED TO DEVELOP FOR THIS AFTERNOON,  
WITH A LIGHT AND VARIABLE WIND RETURNING FOR TONIGHT. MAXIMUM  
TEMPERATURES THIS AFTERNOON WILL AGAIN BE WELL ABOVE NORMAL, WITH  
HIGHS MOSTLY FROM THE UPPER 70S INTO THE MIDDLE 80S. TONIGHT'S LOWS  
SHOULD FAVOR THE 50S WITH SOME FOG EXPECTED.  
 

 
   
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
 
 
TEMPERATURES STILL ON THE MILD SIDE, HOWEVER A DOWNWARD TREND BEGINS.  
 
DESPITE HIGH PRESSURE BECOMING MORE AND MORE CENTERED TO OUR  
NORTHEAST, IT WILL STILL REMAIN IN CONTROL OF OUR WEATHER THROUGH  
THURSDAY. WHILE SOME HIGH CLOUDS MAY START TO ARRIVE THURSDAY  
MORNING, CONDITIONS LOOK FAVORABLE ONCE AGAIN FOR EARLY MORNING  
PATCHY FOG ESPECIALLY IN PARTS OF EASTERN PENNSYLVANIA AND NORTHERN  
NEW JERSEY. WE WILL BEGIN TO SEE SOME SIGNS OF CHANGE ON THURSDAY,  
AS THERE SHOULD BE AT LEAST SOME INCREASE IN HIGH CLOUDS BY THE END  
OF THE DAY. OVERALL THOUGH, EXPECT ONE MORE MILD AND DRY DAY WITH  
HIGHS MOSTLY IN THE MID TO UPPER 70S. MORE OF AN EAST TO EAST-  
SOUTHEAST WIND THOUGH WILL KEEP IN COOLER ALONG THE COAST.  
 
THICKER CLOUDS WILL START TO OVERSPREAD OUR REGION THURSDAY NIGHT  
INTO FRIDAY MORNING. THE LOW-LEVEL FLOW WILL BE FROM THE EAST TO  
SOUTHEAST, AND THIS WILL START TO INCREASE THE LOWER LEVEL MOISTURE  
WITH TIME. SOME STRATUS MAY DEVELOP LATER THURSDAY NIGHT AND FRIDAY  
MORNING AS MOISTURE ADVECTION TEAMS UP WITH SOME INCREASE IN THE  
WARM AIR ADVECTION. THIS COULD ALSO RESULT IN A FEW SHOWERS OR EVEN  
SOME DRIZZLE ASSUMING THE STRATUS FORMS. CONFIDENCE REMAINS LOW ON  
HOW THIS PLAYS OUT THEREFORE KEPT THE POPS THROUGH MIDDAY FRIDAY ON  
THE LOW SIDE. GUIDANCE GENERALLY AGREES THAT A WEAK SHORTWAVE WILL  
BE APPROACHING OUR AREA FROM THE WEST-SOUTHWEST FRIDAY AFTERNOON,  
WELL IN ADVANCE OF THE MAIN UPPER-LEVEL TROUGH AND ASSOCIATED  
SURFACE COLD FRONT TRACKING ACROSS THE GREAT LAKES AND THE OHIO  
VALLEY. DEEPER MOISTURE AND FORCING AS WELL AS INSTABILITY LOOKS  
LIKE IT WILL BE LIMITED AT THAT TIME, SO WHILE SOME THUNDER CANNOT  
BE COMPLETELY RULED OUT, OPTED TO KEEP A MENTION OUT FOR NOW.  
CONDITIONS WILL STILL BE MILD AND EVEN MORE HUMID WITH HIGHS IN THE  
70S. THE SHOWERS SHOULD THEN START TO INCREASE SOME FRIDAY NIGHT,  
ESPECIALLY ACROSS THE WESTERN AREAS.  
 

 
   
LONG TERM /SATURDAY THROUGH TUESDAY/
 
 
SUMMARY...TURNING MUCH COOLER TO COLDER AND EVENTUALLY MUCH  
DRIER OVER THE WEEKEND INTO EARLY NEXT WEEK. SHOWERS SATURDAY AS  
A STRONG COLD FRONT MOVES THROUGH, THEN MAINLY DRY.  
 
SYNOPTIC OVERVIEW...AN UPPER-LEVEL TROUGH LOOKS TO CLOSE OFF AS IT  
SHIFTS ACROSS THE GREAT LAKES AND VICINITY SATURDAY, THEN REMAINS  
ACROSS THE EAST SUNDAY THROUGH EARLY NEXT WEEK. A STRONG COLD FRONT  
CROSSES OUR AREA SATURDAY, THEN CYCLONIC FLOW AND MUCH COOLER TO  
COLDER AIR DOMINATES THROUGH EARLY NEXT WEEK.  
 
FOR SATURDAY...A SHARP UPPER-LEVEL TROUGH IS FORECAST TO CLOSE OFF  
ACROSS THE GREAT LAKES SATURDAY AS IT GRADUALLY SHIFTS EASTWARD. A  
STRONG SHORTWAVE IS FORECAST TO ROUND ITS BASE ACROSS THE UPPER OHIO  
VALLEY AND THE EASTERN GREAT LAKES. AS SURFACE LOW PRESSURE OCCLUDES  
ACROSS THE EASTERN GREAT LAKES, A TRAILING COLD FRONT IS FORECAST TO  
CROSS OUR AREA DURING SATURDAY. FORCING FOR ASCENT WITH THE COLD  
FRONT AND TROUGH ALOFT WILL MAINTAIN SHOWERS. THE STRONGEST FORCING  
MAY REMAIN TO OUR WEST GIVEN THE MAIN TROUGH HANGING BACK WELL TO  
OUR WEST UNTIL SATURDAY EVENING. ISOLATED THUNDER CANNOT BE RULED  
OUT, ESPECIALLY ACROSS THE NORTHERN AREAS AS SOME ENHANCEMENT TO A  
BAND OF SHOWERS MAY OCCUR IN THE AFTERNOON AS THE MAIN TROUGH STARTS  
TO ARRIVE. IT IS THERE WERE SOME GUIDANCE SHOWS AN AXIS OF WEAK  
INSTABILITY POTENTIALLY BECOMING MORE FOCUSED. GIVEN THAT THE  
INSTABILITY LOOKS TO BE ON THE LIMITED SIDE AND THE STRONGEST FLOW  
HANGS BACK TO OUR WEST, SEVERE THUNDERSTORMS ARE NOT ANTICIPATED.  
TEMPERATURES WILL DEPEND ON HOW QUICKLY THE FRONT CLEARS THE REGION,  
BUT MAY FEATURE HIGHS OCCURRING EARLIER IN THE DAY. SOUTHERLY WINDS  
WILL INCREASE SOME AHEAD OF THE COLD FRONT, THEN QUICKLY BECOME WEST  
TO NORTHWEST IN THE WAKE OF THE COLD FRONT AND INCREASE MORE AS  
STRONG COLD AIR ADVECTION TAKES OVER. MUCH COOLER TO COLDER AIR AND  
TUMBLING DEW POINTS WILL OVERSPREAD THE AREA IN THE WAKE OF THE COLD  
FRONT, AND ANY SHOWERS SHOULD BE ENDING SATURDAY NIGHT.  
 
FOR SUNDAY THROUGH TUESDAY...AN UPPER-LEVEL TROUGH/CLOSED LOW IS  
FORECAST TO DOMINATE THE EAST. CYCLONIC FLOW ALONG WITH COLD AIR  
ALOFT MAY RESULT IN STRATOCUMULUS DEVELOPING OVERHEAD OR SPREADING  
IN FROM THE WEST AT LEAST DURING SUNDAY AND MONDAY. A TIGHTENED  
PRESSURE GRADIENT COUPLED WITH DEEPER MIXING WITHIN THE BOUNDARY  
LAYER WILL RESULT IN A CHILLY BREEZE WHICH WILL ALSO BE GUSTY FOR  
MUCH OF THIS TIME FRAME. THE FLOW HOWEVER MAY START TO BACK TO THE  
WEST-SOUTHWEST MONDAY AND TUESDAY AS THE CLOSED LOW MAY SHIFT  
WESTWARD SOME ACROSS THE GREAT LAKES REGION. THERE SHOULD BE SOME  
LAKE RESPONSE, HOWEVER MUCH OF THOSE SHOWERS SHOULD REMAIN CLOSER TO  
THE EASTERN GREAT LAKES ESPECIALLY AS THE FLOW BACKS MORE WITH TIME.  
STILL CANNOT RULE OUT SOME BRIEF SHOWERS OR SPRINKLES SUNDAY INTO  
MONDAY MANLY FOR THE POCONO REGION. HIGH TEMPERATURES IN THE 50S TO  
LOW 60S SUNDAY AND MONDAY (SOME 40S IN THE POCONOS), THEN A LITTLE  
MILDER TUESDAY AS THE AIR MASS STARTS TO SLIGHTLY WARM ALOFT.  
WIDESPREAD 40S AT NIGHT ARE FORECAST, WITH EVEN SOME UPPER 30S  
MAINLY IN THE POCONOS.  
 

 
   
AVIATION /07Z WEDNESDAY THROUGH SUNDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS...  
 
TODAY...EARLY MORNING RESTRICTIONS ARE EXPECTED DUE TO FOG.  
OTHERWISE, VFR UNDER A MOSTLY CLEAR SKY FROM LATE THIS MORNING INTO  
THIS AFTERNOON. VARIABLE WIND 5 KNOTS OR LESS, BECOMING SOUTHERLY 4  
TO 8 KNOTS IN THE AFTERNOON. MEDIUM CONFIDENCE IN THE EXTENT OF THE  
MORNING FOG, OTHERWISE HIGH CONFIDENCE IN VFR CONDITIONS FOR THE  
LATE MORNING AND AFTERNOON.  
 
TONIGHT...VFR UNDER A MOSTLY CLEAR SKY. AREAS OF FOG MAY IMPACT SOME  
OF OUR TAF SITES AFTER 06Z. VARIABLE WIND 5 KNOTS OR LESS. MEDIUM TO  
HIGH CONFIDENCE.  
 
OUTLOOK...  
 
THURSDAY...VFR. SOME LOW CLOUDS MAY DEVELOP HOWEVER LATE AT NIGHT.  
LIGHT AND VARIABLE WINDS BECOMING SOUTHEASTERLY 5-10 KNOTS. LOW  
CONFIDENCE REGARDING LOW CLOUD DEVELOPMENT.  
 
FRIDAY...A PERIOD OF MVFR, POSSIBLY IFR, WITH A CHANCE FOR SOME  
SHOWERS DURING THE DAY AND ESPECIALLY AT NIGHT. SOUTHEAST WINDS  
5-10 KNOTS. LOW CONFIDENCE.  
 
SATURDAY...MVFR/IFR CONDITIONS WITH SHOWERS. SOUTHWEST WINDS  
5-10 KNOTS BECOMING WEST TO NORTHWEST 10-15 KNOTS AND POSSIBLY  
GUSTY. LOW CONFIDENCE.  
 
SUNDAY...MAINLY VFR. WESTERLY WINDS 10-20 KNOTS WITH GUSTS TO AROUND  
25 KNOTS. THE WINDS SHOULD DIMINISH SOME AT NIGHT. MODERATE  
CONFIDENCE.  
 

 
   
MARINE
 
 
A LIGHT AND VARIABLE WIND THIS MORNING IS FORECAST TO BECOME SOUTH  
TO SOUTHEAST 5 TO 10 KNOTS THIS AFTERNOON. THE WIND IS EXPECTED TO  
BACK TOWARD THE EAST TONIGHT. WAVE HEIGHTS ON OUR OCEAN WATERS ARE  
EXPECTED TO BE 2 TO 3 FEET, WITH WAVES ON DELAWARE BAY AT 2 FEET OR  
LESS.  
 
OUTLOOK...  
 
THURSDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL  
CRAFT ADVISORY CRITERIA.  
 
FRIDAY AND SATURDAY...SMALL CRAFT ADVISORY PROBABLE, MAINLY DUE TO  
SEAS ON THE OCEAN ZONES THAT MAY BUILD TO 5 FEET FRIDAY NIGHT THEN  
TO 5-7 FEET SATURDAY. SOUTHEAST TO SOUTHWEST WINDS WILL INCREASE  
SOME, HOWEVER THE STRONGEST WINDS (POSSIBLY GUSTING TO 25-30 KNOTS)  
SHOULD OCCUR SATURDAY WITH A WIND SHIFT FROM THE WEST AND NORTHWEST  
IN THE WAKE OF A STRONG COLD FRONT.  
 
SUNDAY...SMALL CRAFT ADVISORY CONDITIONS PROBABLE DUE TO GUSTY WINDS  
AND ELEVATED SEAS.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...GORSE  
NEAR TERM...IOVINO  
SHORT TERM...DODD/GORSE  
LONG TERM...GORSE  
AVIATION...GORSE/IOVINO  
MARINE...GORSE/IOVINO  
 
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