127  
FXUS61 KPHI 260432  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
1232 AM EDT FRI MAY 26 2017  
   
SYNOPSIS
 
 
AN AREA OF LOW PRESSURE WILL MOVE AWAY TO OUR NORTHEAST THROUGH  
FRIDAY. A WEAK SURFACE TROUGH IS EXPECTED TO CROSS THE AREA  
DURING THE DAY FRIDAY. WEAK HIGH PRESSURE MAY BRIEFLY MOVE  
ACROSS THE AREA FRIDAY NIGHT INTO EARLY SATURDAY. A WEAK LOW IS  
FORECAST TO MOVE ALONG A DEVELOPING STATIONARY FRONT TO OUR  
SOUTH SATURDAY INTO SATURDAY NIGHT. ANOTHER AREA OF LOW PRESSURE  
IS FORECAST TO WEAKEN AS IT MOVES INTO THE EASTERN GREAT LAKES  
SUNDAY INTO SUNDAY NIGHT, THEN AN OCCLUDED FRONTAL SYSTEM IS  
EXPECTED TO AFFECT THE AREA SUNDAY NIGHT INTO EARLY MONDAY. A  
SERIES OF COLD FRONTS ARE FORECAST TO MOVE ACROSS THE AREA  
MONDAY THROUGH WEDNESDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
THE MID LEVEL LOW WAS PASSING OVER SOUTHERN NEW JERSEY AND  
VICINITY AROUND MIDNIGHT. IT SHOULD REACH SOUTHEASTERN NEW  
ENGLAND AROUND DAYBREAK. MEANWHILE, THE SURFACE LOW WAS OFF THE  
NORTHERN PART OF THE NEW JERSEY COAST AROUND MIDNIGHT. IT IS  
FORECAST TO MOVE EAST NORTHEASTWARD OFF THE COAST OF LONG ISLAND  
BEFORE APPROACHING CAPE COD AROUND DAYBREAK.  
 
THE RAIN SHOWERS OVER OUR REGION WILL CONTINUE TO DIMINISH  
DURING THE BALANCE OF THE NIGHT. WE HAVE REMOVED ANY MENTION OF  
THUNDER BASED ON THE RADAR AND LIGHTNING DATA TRENDS OVER THE  
PAST HOUR OR SO.  
 
THE SKY SHOULD REMAIN OVERCAST IN EASTERN PENNSYLVANIA AND  
NORTHERN AND CENTRAL NEW JERSEY. SOME BREAKS IN THE CLOUD COVER  
ARE ANTICIPATED FOR NORTHEASTERN MARYLAND, DELAWARE AND SOUTHERN  
NEW JERSEY.  
 
A SOUTHWEST TO WEST WIND AROUND 5 TO 10 MPH IS EXPECTED IN THE  
SOUTHERN PART OF OUR FORECAST AREA. THE WIND SHOULD BE SLOWER TO  
INCREASE IN THE NORTH. AS A RESULT, LINGERING LOW LEVEL  
MOISTURE MAY DEVELOP INTO ADDITIONAL LOW CLOUDS AND PATCHY FOG  
THERE.  
 
LOW TEMPERATURES ARE ANTICIPATED TO FAVOR THE 50S.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SATURDAY/
 
 
THE MAIN UPPER LOW SHIFTS INTO NEW ENGLAND ON FRIDAY, WITH  
WESTERLY FLOW PREVAILING ACROSS THE AREA DURING THE DAY. SEVERAL  
PERTURBATIONS IN THE FLOW ARE LIKELY TO MOVE THROUGH THE AREA  
DURING THE DAY, ESPECIALLY IN THE MORNING. THIS SHOULD KEEP  
SKIES PARTIALLY TO MOSTLY CLOUDY MOST OF THE DAY, AND MAY ALLOW  
FOR A SPRINKLE OR LIGHT SHOWER TO OCCUR, ESPECIALLY NORTH OF THE  
MASON-DIXON LINE. THE 18Z NAM HAS A FEW SHOWERS FARTHER TO THE  
SOUTH AS A VORT MAX ROTATES SOUTHEASTWARD THROUGH THE MID-  
ATLANTIC AROUND MIDDAY, BUT THERE IS NOT A LOT OF SUPPORT FROM  
HIGHER-RESOLUTION GUIDANCE AT THE MOMENT. AS SUCH, KEPT POPS LOW  
OR NON-MENTIONABLE FOR THE MOST PART SOUTH OF THE I-78/I-195  
CORRIDOR.  
 
MAIN SENSIBLE WEATHER IMPACT TOMORROW MAY BE THE WINDS, WITH  
SOME STRONGER MIXING LIKELY TO OCCUR DURING THE AFTERNOON HOURS.  
WINDS ABOVE THE BOUNDARY LAYER ARE NOT PARTICULARLY STRONG  
(20-30 KTS), BUT GUSTS OF 20-30 MPH ARE LIKELY BY AFTERNOON  
ACROSS MOST OF THE AREA.  
 
FORECAST MAX TEMPERATURES RANGE FROM THE MID 60S IN THE POCONOS  
TO THE MID 70S IN THE URBAN CORRIDOR TO AROUND 80 IN SOUTHERN  
DELMARVA.  
 

 
   
LONG TERM /SATURDAY THROUGH FRIDAY/
 
 
AN UNSETTLED WEATHER PATTERN CONTINUES FOR MUCH OF THE EXTENDED  
FORECAST WITH SEVERAL PERIODS OF RAIN POSSIBLE.  
 
FRIDAY NIGHT THROUGH THE EARLY PART OF SATURDAY IS EXPECTED TO  
BE MOSTLY DRY AS WEAK HIGH PRESSURE QUICKLY MOVES ACROSS THE  
AREA. HOWEVER, LATER IN THE DAY, A WEAK AREA OF LOW PRESSURE  
WILL BE APPROACHING FROM THE WEST BUT PASSING TO OUR SOUTH ALONG  
A DEVELOPING FRONTAL BOUNDARY TO OUR SOUTH. ALSO, A SHORT  
WAVE/VORTICITY IMPULSE IS EXPECTED TO MOVE ACROSS THE AREA  
DURING THE DAY, SO THERE WILL BE A CHANCE OF AN ISOLATED SHOWER  
DURING THE DAY SATURDAY.  
 
ON SATURDAY NIGHT, THE FRONTAL BOUNDARY IS EXPECTED TO REMAIN  
TO OUR SOUTH, BUT SHOULD BEGIN LIFTING NORTHWARD TOWARD THE AREA  
SUNDAY. IT WILL LIKELY NOT MAKE ITS WAY INTO THE AREA UNTIL  
SUNDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS OVERNIGHT  
SATURDAY INTO SUNDAY, BUT THE BEST CHANCE OF SHOWERS IS EXPECTED  
TO BE SUNDAY NIGHT AS THE OCCLUDED FRONT MOVES INTO THE AREA.  
 
A SERIES OF COLD FRONTS ARE FORECAST TO MOVE ACROSS THE AREA  
MONDAY THROUGH WEDNESDAY OF NEXT WEEK AS LOW PRESSURE REMAIN  
NEARLY STATIONARY ACROSS SOUTHERN CANADA JUST NORTH OF THE GREAT  
LAKES REGION.AS ANY SHORT WAVE/VORTICITY IMPULSES SLIDE ACROSS  
THE AREA, THEY COULD LEAD TO ADDITIONAL SHOWERS OR THUNDERSTORMS  
EARLY NEXT WEEK.  
 
HIGH PRESSURE TRIES TO BUILD BACK INTO THE AREA FOR THURSDAY,  
WHICH WOULD PROVIDE A DRY FORECAST.  
 

 
   
AVIATION /04Z FRIDAY THROUGH TUESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
GENERALLY A MIX OF VFR AND MVFR CONDITIONS FOR THE BALANCE OF  
THE NIGHT. A LIGHT AND VARIABLE WIND AND LINGERING LOW LEVEL  
MOISTURE COULD BRING SOME IFR CONDITIONS, MAINLY TO KRDG, KABE  
AND KTTN. A WEST WIND IS FORECAST TO INCREASE TO 5 TO 10 KNOTS  
AT KPNE, KPHL, KILG, KMIV AND KACY. SHOWERS WILL CONTINUE TO BE  
ON THE DECREASE.  
 
VFR CONDITIONS DEVELOP FRIDAY MORNING. WINDS VEER TO THE W-NW  
LATE FRIDAY MORNING, AND INCREASE TO 15-20 KT WITH GUSTS UP TO  
23 KT.  
 
OUTLOOK...  
 
FRIDAY NIGHT...GENERALLY VFR.  
 
SATURDAY...GENERALLY VFR. SHOWERS MOVING INTO THE AREA LATER IN  
THE DAY, WHICH COULD LEAD TO LOWERING CEILINGS.  
 
SATURDAY NIGHT-SUNDAY...MVFR CIGS POSSIBLE. CHANCE OF SCATTERED  
SHOWERS.  
 
SUNDAY NIGHT...MVFR TO IFR CONDITIONS POSSIBLE WITH PERIODS OF  
LOW CLOUDS AND RAIN.  
 
MONDAY...GENERALLY IMPROVING TO VFR DURING THE MORNING.  
SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE DURING THE DAY.  
 
MONDAY NIGHT-TUESDAY...GENERALLY VFR. CHANCE OF SHOWERS OR  
THUNDERSTORMS ON TUESDAY.  
 

 
   
MARINE
 
 
SMALL CRAFT ADVISORY CONTINUES, MAINLY FOR HIGH SEAS, THROUGH  
FRIDAY AFTERNOON. SEAS AT THE BUOYS HAVE INCREASED TO 5-6 FEET.  
GUSTS TO 25 KT WILL DEVELOP TONIGHT, AND THEN GUSTY W-NW WINDS  
COULD CONTINUE TO GUST TO 25 KT ON FRIDAY.  
 
SHOWERS AND THUNDERSTORMS LIKELY ON THE WATERS TONIGHT. GUSTY  
WINDS, SMALL HAIL, AND FREQUENT CLOUD-TO-GROUND LIGHTNING ARE  
ALL THREATS FROM THESE STORMS. LOCALLY STRONG WINDS/ROUGH SEAS  
ARE LIKELY IN VICINITY OF THESE STORMS.  
 
WINDS BECOME WESTERLY ON FRIDAY. A LIGHT SHOWER OR TWO MAY  
OCCUR, ESPECIALLY OFF THE NEW JERSEY COAST.  
 
RIP CURRENTS...  
 
WITH INCREASING WESTERLY WINDS DEVELOPING DURING THE DAY  
FRIDAY, WILL KEEP A MODERATE RISK FOR THE DEVELOPMENT OF  
DANGEROUS RIP CURRENTS IN THE FORECAST.  
 
OUTLOOK...  
 
FRIDAY NIGHT-TUESDAY...CONDITIONS EXPECTED TO REMAIN BELOW  
ADVISORY LEVELS, ALTHOUGH WINDS MAY GUST AROUND 20 KNOTS AT  
TIMES.  
 

 
   
TIDES/COASTAL FLOODING
 
 
WIDESPREAD MINOR FLOODING OCCURRED ALONG THE COASTS OF NEW  
JERSEY AND DELAWARE THIS EVENING AND INTO RARITAN BAY, THE BACK  
BAYS AND DELAWARE BAY. THERE WAS SOME LOCALLY MODERATE FLOODING  
ALONG THE NEW JERSEY SHORE. THE HIGH TIDE HAS ALL BUT RUN ITS  
COURSE AND WE WILL LET THE COASTAL FLOOD ADVISORY COME TO AN  
END.  
 
WE WILL TAKE A CLOSER LOOK AT TRENDS TO DETERMINE WHETHER  
ANOTHER ADVISORY WILL BE NEEDED FOR FRIDAY EVENING. THE WIND  
SHOULD BE FROM THE WEST TODAY ALLOWING WATER TO DRAIN AWAY FROM  
THE COAST. HOWEVER, THE ASTRONOMICAL TIDES REMAIN QUITE HIGH.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR  
ANZ450>455.  
 

 
 

 
 
SYNOPSIS...ROBERTSON  
NEAR TERM...IOVINO  
SHORT TERM...CMS  
LONG TERM...ROBERTSON  
AVIATION...CMS/ROBERTSON/MPS  
MARINE...CMS/ROBERTSON/MPS  
TIDES/COASTAL FLOODING...IOVINO  
 
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