999  
FXUS61 KPHI 290539  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
139 AM EDT FRI MAR 29 2024  
   
SYNOPSIS
 
 
LOW PRESSURE MOVES UP TOWARD NOVA SCOTIA EARLY THIS MORNING AS  
COLD FRONT MOVES OFF THE COAST, THEN HIGH PRESSURE BRIEFLY  
BUILDS IN LATER TODAY. A WEAK CLIPPER SYSTEM PASSES THROUGH  
LATE ON SATURDAY WITH DRYING EXPECTED ON SUNDAY. AN AREA OF LOW  
PRESSURE WILL DEVELOP OVER THE CENTRAL PLAINS ON MONDAY WITH A  
WARM FRONT EXTENDING EAST INTO THE MID- ATLANTIC. THIS WILL LEAD  
TO UNSETTLED CONDITIONS THROUGH AT LEAST THE MIDDLE PORTION OF  
NEXT WEEK BEFORE DRYING OUT ON THURSDAY.  
 

 
   
NEAR TERM /THROUGH TODAY/
 
 
A FRONT HAS PUSHED OFFSHORE. A SURFACE LOW PRESSURE WILL PASS BY  
OFFSHORE AND WILL MOVE TOWARDS THE CANADIAN MARITIMES THIS  
AFTERNOON. SURFACE HIGH PRESSURE WILL BUILD THROUGH TODAY AS AN  
H5 TROUGH PASSES THROUGH THE EAST COAST DURING THE DAY.  
 
THE RAIN HAS MOVED OFFSHORE AS OF 1 AM. SKIES WILL CLEAR OUT  
FROM WEST TO EAST BEFORE DAWN, AND THEN SKIES WILL BE MOSTLY  
SUNNY DURING THE DAYTIME, THOUGH SOME MID AND HIGH CLOUDS ARE  
POSSIBLE WITH THE PASSAGE OF THE TROUGH.  
 
A TIGHT PRESSURE GRADIENT FORMS BETWEEN LOW PRESSURE TO THE EAST AND  
HIGH PRESSURE BUILDING IN FROM THE WEST. NORTHWEST WINDS WILL  
INCREASE TO 10 TO 15 MPH TONIGHT, AND THEN WILL INCREASE FURTHER TO  
15 TO 20 MPH WITH 30 TO 35 MPH GUSTS FOR MOST OF FRIDAY. ALTHOUGH  
NORTHWEST FLOW WILL BE IN PLACE BEHIND A DEPARTING COLD FRONT ON  
FRIDAY, THERE WILL BE ENOUGH SUNSHINE ON FRIDAY FOR HIGH  
TEMPERATURES TO RISE INTO THE MID AND UPPER 50S.  
 

 
   
SHORT TERM /TONIGHT THROUGH SUNDAY/
 
 
HIGH PRESSURE WILL BE LOCATED OFF THE SOUTHEAST US ON FRIDAY NIGHT  
AS THE AREA LIES IN BETWEEN LOW PRESSURE SYSTEMS. WINDS WILL  
NOTICEABLY DIMINISH OVERNIGHT AS MOST AREAS WILL SETTLE UNDERNEATH  
THE SURFACE INVERSION. HOWEVER, BREEZY CONDITIONS WILL CONTINUE AT  
HIGHER ELEVATIONS IN EXCESS OF 30 MPH. LOWS WILL BE IN THE 30S  
AREAWIDE WITH CLEAR SKIES.  
 
OVERALL, THE START OF THE WEEKEND WILL BE QUITE SEASONABLE WITH  
WIDESPREAD SUNSHINE FOR SATURDAY MORNING. TEMPS WILL REBOUND NICELY  
THROUGH THE DAY WITH HIGHS RANGING IN THE MID TO UPPER 50S TO LOW  
60S UNDER MODEST SOUTHWEST FLOW; WHICH WILL AID AFTERNOON MIXING.  
HOWEVER, THE SUNNY WEATHER WILL BE SHORT-LIVED AS CLOUDS INCREASE  
THROUGH THE AFTERNOON AS A WEAK CLIPPER SYSTEM TRANSVERSES ACROSS  
THE AREA EARLY SATURDAY NIGHT. THIS SYSTEM WILL BE WEAKENING AS IT  
APPROACHES SO NOT EXPECTING A WASHOUT BY ANY MEANS. ISOLATED TO  
SCATTERED RAIN SHOWERS ARE EXPECTED LATE SATURDAY INTO EARLY  
SATURDAY NIGHT BEFORE MOVING AWAY FROM THE AREA. THE BEST CHANCE FOR  
SHOWER ACTIVITY IS NORTH OF THE PHILADELPHIA AREA. RAINFALL AMOUNTS  
ARE MINIMAL, GENERALLY LESS THAN A TENTH OF AN INCH.  
 
AFTER THE CLIPPER SYSTEM PASSES BY, WEAK HIGH PRESSURE WILL BUILD IN  
FROM THE GREAT LAKES AND ACROSS THE NORTHEAST. THIS SHOULD RESULT IN  
QUIET WEATHER ON SUNDAY UNDER PARTLY CLOUDY SKIES. ALL IN ALL, A  
NICER DAY IS EXPECTED WITH HIGHS IN THE 60S DESPITE A GUSTY  
NORTHWESTERLY BREEZE.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
 
 
THE LONG TERM PERIOD WILL BE QUITE DIFFERENT FROM THE SHORT TERM AS  
AN ACTIVE, WET, AND UNSETTLED PERIOD LOOMS. A STALLED FRONTAL  
BOUNDARY WILL BE LOCATED OVER THE CAROLINAS AS A LOW PRESSURE SYSTEM  
DEVELOPS OVER THE CENTRAL PLAINS. THIS SYSTEM WILL EXTEND A WARM  
FRONT EASTWARD INTO THE MID-ATLANTIC REGION BEGINNING AS EARLY AS  
MONDAY. THE WARM FRONT WILL CONTINUE TO NOSE EASTWARD WITH TIME AS  
THE LOW TRANSLATES EAST TOWARD THE GREAT LAKES REGION BY WEDNESDAY.  
 
THIS WILL LEAD TO SEVERAL OPPORTUNITIES FOR RAIN TO BE DIRECTED  
TOWARD OUR REGION. THE FIRST COMES SUNDAY NIGHT INTO MONDAY WHERE  
POPS ARE AROUND 40-60% ACROSS THE REGION. A MORE STEADIER PERIOD  
LOOKS TO OCCUR MONDAY NIGHT THROUGH MUCH OF TUESDAY AS POPS FURTHER  
INCREASE TO 60-80% AREAWIDE. DEPENDING ON THE TRACK, EVOLUTION AND  
TIMING OF THE LOW WILL DETERMINE HOW LONG RAIN LINGERS ACROSS THE  
AREA. MODEL GUIDANCE THIS AFTERNOON CONTINUES TO SHOW THE AREA OF  
LOW PRESSURE LIFTING INTO THE GREAT LAKES, THEN TRANSFERRING ITS  
ENERGY TO A STRENGTHENING COASTAL LOW THAT LIFTS NORTHEAST TOWARD  
NEW ENGLAND. A RATHER POTENT UPPER-TROUGH WILL DROP SOUTHEASTWARD  
ACROSS THE GREAT LAKES AND POSSIBLY PHASE WITH THE AFOREMENTIONED  
TROUGH, SUPPORTING THIS STRONG AREA OF LOW PRESSURE. WILL HAVE TO  
MONITOR THIS SYSTEM FOR SOME HEAVY RAIN POTENTIAL, FOLLOWED BY SOME  
GUSTY WINDS LATER WEDNESDAY INTO THURSDAY.  
 

 
   
AVIATION /06Z FRIDAY THROUGH TUESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
THROUGH 12Z...VFR WITH SKIES CLEARING. NW WINDS AROUND 10 KTS  
WITH SOME GUSTS UP TO 20 KTS POSSIBLE. 2KFT WINDS WILL INCREASE  
TO NEAR 40 KTS THROUGH 12Z. WITH A LACK OF GUSTS AT THE SURFACE  
AS OF 06Z, HAVE OPTED TO ADD AN LLWS MENTION IN ALL TAFS. HIGH  
CONFIDENCE IN PREVAILING CONDITIONS.  
 
FRIDAY...VFR. NW/WNW WINDS 10-20 KTS WITH GUSTS OF 25-30 KTS.  
HIGH CONFIDENCE.  
 
OUTLOOK...  
 
FRIDAY NIGHT...VFR/SKC. W-NW WINDS AROUND 5-10 KT. HIGH CONFIDENCE.  
 
SATURDAY...VFR EARLY, WITH SUB-VFR LATER IN THE DAY WITH ISOLATED TO  
SCATTERED RAIN SHOWERS. SW-W WINDS AROUND 10-15 KT. MODERATE  
CONFIDENCE.  
 
SUNDAY...VFR EXPECTED UNDER PARTLY CLOUDY SKIES. SLIGHT CHANCE OF  
RAIN SHOWERS AT NIGHT. W-NW WINDS AROUND 15-20 KT. MODERATE  
CONFIDENCE.  
 
MONDAY AND TUESDAY...SUB-VFR EXPECTED WITH PERIODS OF LIGHT RAIN. E-  
SE WINDS AROUND 10 KT ON MONDAY, BECOMING NE WINDS ON TUESDAY. LOW  
CONFIDENCE.  
 

 
   
MARINE
 
 
NORTHWEST WINDS 15-20 KTS WILL RAMP UP TO AROUND 20-25 KTS WITH  
30-35 KTS GUSTS THROUGH EARLY THIS MORNING. A GALE WARNING  
REMAINS IN EFFECT, THOUGH GALE GUSTS OF 34 KTS OR HIGHER MAY  
ONLY OCCUR FOR A 2 TO 3 HOUR WINDOW. GUIDANCE CONTINUES TO BE  
ON A DOWNWARD TREND REGARDING THE POSSIBILITY OF GALE FORCE  
WINDS. HOWEVER, GIVEN THE METEOROLOGY OF THE SITUATION (E.G.,  
ANTICIPATED MIXING) WILL KEEP THE GALE WARNING IN EFFECT. THE  
BEST CHANCES FOR GALES WILL BE ON DELAWARE BAY AND THE DELAWARE  
OCEAN WATERS.  
 
WNW WINDS WILL RANGE FROM 20-30 KTS FOR THE REMAINDER OF THE DAY.  
A SMALL CRAFT ADVISORY WILL BE NEEDED ONCE THE GALE WARNING  
COMES DOWN.  
 
OUTLOOK...  
 
FRIDAY NIGHT...SCA CONDITIONS LIKELY CONTINUE. W-NW WINDS AROUND 15-  
20 KT WITH GUSTS UP TO 25 KT. SEAS OF 3-5 FEET.  
 
SATURDAY THROUGH SUNDAY...NO MARINE HEADLINES EXPECTED. SW WINDS  
AROUND 10-20 KT ON SATURDAY, BECOMING W-NW AROUND 10-15 KT ON  
SUNDAY. SEAS OF 3-4 FEET.  
 
MONDAY THROUGH TUESDAY...NO MARINE HEADLINES EXPECTED. NE-E WINDS  
AROUND 10-15 KT ON MONDAY, BECOMING E-SE AROUND 15-20 KT ON TUESDAY.  
SEAS OF 2-4 FEET.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...GALE WARNING UNTIL 10 AM EDT THIS MORNING FOR ANZ430-431-  
450>455.  
 

 
 

 
 
SYNOPSIS...DESILVA/STAARMANN  
NEAR TERM...MPS/STAARMANN/WUNDERLIN  
SHORT TERM...DESILVA  
LONG TERM...DODD/DESILVA  
AVIATION...DESILVA/MPS/STAARMANN/WUNDERLIN  
MARINE...DESILVA/MPS/WUNDERLIN  
 
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