640  
FXUS61 KPHI 071036  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
636 AM EDT THU JUL 7 2022  
   
SYNOPSIS
 
 
A WEAK TROUGH WILL CROSS THE REGION TODAY. TOMORROW, A COLD FRONT  
WILL APPROACH THE AREA FROM THE NORTH THEN CROSS THROUGH THE REGION  
FRIDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE AREA LATER ON  
SATURDAY BRINGING DRIER AND MORE PLEASANT CONDITIONS THROUGH MONDAY.  
THE HIGH PRESSURE WILL SHIFT OFFSHORE LATE SUNDAY INTO MONDAY THEN  
ANOTHER COLD FRONT WILL APPROACH THE REGION TUESDAY INTO WEDNESDAY  
BRINGING A RETURN OF WARMER AND MORE HUMID CONDITIONS ALONG WITH  
CHANCES OF SHOWERS AND THUNDERSTORMS.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
SHOWERS AND STEADY RAIN IS CURRENTLY MOVING THROUGH THE REGION  
THIS MORNING. THE GOOD NEWS IS THAT THE AFTERNOON WILL TREND  
DRIER AS LOW PRESSURE MOVING ALONG A STATIONARY FRONT MOVES  
OFFSHORE AWAY FROM THE REGION.  
 
SURFACE ANALYSIS EARLY THIS MORNING SHOWS A STATIONARY FRONT THAT IS  
CURRENTLY DRAPED ACROSS THE SOUTHERN PORTIONS OF THE CWA THIS  
MORNING, TRANSECTING EASTERN MARYLAND, DELAWARE, AND FAR SOUTHERN  
NEW JERSEY. A WEAK SURFACE LOW IS ALSO RIDING ALONG THIS FRONT FROM  
WESTERN MARYLAND. THIS CONTINUES TO FOCUS SHOWERS AND A FEW  
THUNDERSTORMS, WITH THE LATTER BEING MOSTLY ALONG AND SOUTH OF THE  
FRONT. SHOWERS HAVE EXTENDED JUST SLIGHTLY FURTHER TO THE NORTH THIS  
MORNING, SO ADJUSTED POPS ACCORDINGLY. MOST THUNDERSTORMS ARE  
OCCURING THANKS TO SOME MODEST MID-LEVEL INSTABILITY. MUCAPE VALUES  
CURRENTLY RANGE FROM 500 TO 1000 J/KG ALONG AND SOUTH OF THE FRONT.  
 
EXPECT SHOWERS AND THUNDERSTORMS TO CONTINUE SOUTH OF THE  
PHILADELPHIA METRO THROUGH THE REST OF THE MORNING AS SHORTWAVE  
IMPULSE REMNANT FROM YESTERDAY'S CONVECTION OVER THE MIDWEST  
TRAVELS ALONG THE FRONT. THE SURFACE LOW ASSOCIATED WITH THIS  
FEATURE WILL DEEPEN A BIT AS IT INTERACTS WITH THE GULF STREAM  
AND MOVES FURTHER OFFSHORE INTO THIS AFTERNOON. WITH INSTABILITY  
BEING STRONGER MOSTLY SOUTH OF THE FRONT, WE AREN'T EXPECTING  
MUCH IN THE WAY OF SEVERE WEATHER, BUT THERE IS POTENTIAL FOR A  
FEW STRONG WIND GUSTS WITH THE MORE ROBUST STORMS ACROSS  
PORTIONS OF DELMARVA.  
 
MOISTURE CONTENT IS QUITE HIGH TODAY WITH PWATS FROM 2 TO 2.25"  
RANGE OVER EASTERN MARYLAND AND SOUTHERN DELAWARE. WE ARE SEEING  
SOME HEFTY RAIN RATES SO FAR THIS MORNING, WHICH WILL CONTINUE  
THROUGH THE MORNING INTO THE EARLY AFTERNOON. LOCALIZED NUISANCE  
FLOODING IS POSSIBLE, BUT WITH THE SURFACE LOW MOVING OUT THIS  
AFTERNOON, NO WIDESPREAD FLOODING IS FORECAST.  
 
HIGHS TODAY WILL RANGE FROM THE LOWER 80S ALONG AND WEST OF THE I-95  
CORRIDOR TO UPPER 70S CLOSER TO THE COAST THANKS TO ONSHORE FLOW ON  
THE NORTH SIDE OF THE SURFACE LOW THAT IS MOVING OVER THE REGION.  
LIGHT NORTHEASTERLY WINDS FROM 5 TO 10 MPH WILL OCCUR THROUGH MUCH  
OF THE DAY BEFORE TURNING LIGHT AND VARIABLE OVERNIGHT. WITH  
MOISTURE FROM TODAY'S SHOWERS AND THUNDERSTORMS AND LIGHT WINDS,  
PATCHY DENSE FOG IS POSSIBLE TONIGHT ACROSS THE AREA. CLOUD COVER  
SHOULD HOLD THROUGH THE NIGHT, WHICH WILL BE ONE FACTOR WORKING  
AGAINST OUR FOG POTENTIAL. LOWS TONIGHT WILL RANGE FROM THE MID TO  
UPPER 60S WITH LOWER 60S OVER THE POCONOS AND NORTHWESTERN NEW  
JERSEY.  
 

 
   
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/
 
 
A MID LEVEL TROUGH EMBEDDED IN THE LARGER SCALE NORTHWESTERLY FLOW  
PATTERN WILL CROSS THE MID ATLANTIC LATE FRIDAY INTO SATURDAY  
MORNING. AT THE SURFACE, A COLD FRONT IS EXPECTED TO DIG SOUTH AS  
THIS OCCURS.  
 
THIS WILL MEAN, THAT UNLIKE MANY OF OUR PRECIPITATION CHANCES  
LATELY, THERE WILL BE PLENTY OF LIFT FOR SOME AREAS. THE RESULT IS  
THE BEST CHANCE FOR MORE WIDESPREAD PRECIPITATION FRIDAY NIGHT INTO  
SATURDAY MORNING ESPECIALLY. THAT BEING SAID, DEPENDING ON THE SPEED  
OF THE SURFACE FRONT AND THE EXACT TRACK OF THE MID LEVEL TROUGH,  
THE AREAS FAVORED TO GET THE WIDESPREAD PRECIPITATION WILL GENERALLY  
BE SOUTH OF PHILADELPHIA.  
 
AS MENTIONED BY THE PREVIOUS SHIFT, INSTABILITY APPEARS TO BE  
LIMITED, EVEN ACROSS NORTHERN DELMARVA WHICH SHOULD KEEP DEWPOINTS  
NEAR 70 FOR MUCH OF THIS PERIOD. MODELS ARE DEPICTING PERSISTENT MID  
LEVEL CLOUDS AND A LOW LEVEL TEMPERATURE INVERSION THROUGH OUT THIS  
PERIOD (NOT SURPRISING GIVEN THE TIME OF DAY THIS MAY BE OCCURING).  
CONSEQUENTLY MODEL SOUNDINGS SHOW MU CAPE VALUES GENERALLY 500 J/KG  
OR LESS. THERE IS SOME WEAK DIRECTIONAL SHEAR THROUGH THIS PERIOD,  
ESPECIALLY IN THE VICINITY OF THE FRONT, SO IF AN UPDRAFT CAN GET  
THROUGH THE LOW LEVEL TEMPERATURE INVERSION, THERE IS A CHANCE THAT  
CONVECTION COULD BE ORGANIZED, BUT THE SEVERE RISK APPEARS TO BE LOW  
AT THIS TIME.  
 
THERE WILL BE SOME CHANCES FOR SHOWERS AND THUNDERSTORMS OUTSIDE OF  
THIS PERIOD, BUT IN THOSE CASES, CONVECTION WILL BE WEAKLY FORCED,  
AND THUS SHOULD BE ISOLATED IN COVERAGE.  
 
GIVEN THAT THE COLD FRONT SHOULD STAY WELL NORTH OF THE REGION  
DURING THE DAY ON FRIDAY, TEMPERATURES SHOULD BE NEAR TO SLIGHTLY  
ABOVE NORMAL, WITH HIGHS MOSTLY IN THE 80S. BY SATURDAY, ASSUMING  
THE FRONT ARRIVES ON TIME, TEMPERATURES SHOULD BE ABOUT 5 DEGREES  
LOWER THAN FRIDAY, WITH HIGHS RANGING FROM THE MID 70S TO LOWER  
80S.  
 

 
   
LONG TERM /SUNDAY THROUGH WEDNESDAY/
 
 
HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE REGION SUNDAY WHILE  
THE STRONG UPPER RIDGE TO OUR NORTHWEST BEGINS TO BREAK DOWN AND  
MIGRATE TO THE SOUTHEAST. AS THE RIDGE CONTINUES TO WEAKEN AND PUSH  
SOUTHEASTWARD ACCOMPANIED HIGH PRESSURE CONDITIONS SHOULD PERSIST  
OVER THE REGION THROUGH MONDAY WITH COOLER TEMPERATURES AND DRIER  
AIR TO BE EXPECTED. ANOTHER UPPER LEVEL LOW AND ASSOCIATED TROUGH  
APPROACH FROM THE NORTHWEST DURING THE MONDAY NIGHT INTO TUESDAY  
MORNING TIMEFRAME. MODEL GUIDANCE INDICATES THAT THE TROUGH'S  
MOVEMENT COULD BEGIN TO SLOW DOWN SOME THROUGH TUESDAY BRINGING  
THE CHANCE OF WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE  
REGION TUESDAY NIGHT INTO MUCH OF THE DAY WEDNESDAY FROM THE  
ASSOCIATED FRONT.  
 

 
   
AVIATION /12Z THURSDAY THROUGH MONDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
TODAY...MOSTLY VFR WITH SOME POSSIBILITY FOR BRIEF MVFR  
RESTRICTIONS AS SHOWERS AND THUNDERSTORMS MOVE OVER THE REGION  
THIS MORNING THROUGH AROUND 16Z (ENDING FROM WEST TO EAST). SOME  
VSBY RESTRICTIONS ALSO WITH THE RAIN THROUGH 15Z. WINDS OUT OF  
THE EAST-NORTHEAST FROM 5 TO 10 KNOTS. MODERATE CONFIDENCE.  
 
TONIGHT...MVFR RESTRICTIONS LIKELY WITH THE POSSIBILITY FOR EVEN IFR  
RESTRICTIONS WITH PATCHY FOG DEVELOPING. CANNOT ENTIRELY RULE OUT  
SOME ISOLATED SHOWERS, BUT CONFIDENCE IS LOW ON THE EXTENT OF THESE.  
OTHERWISE, MOSTLY MVFR CIGS. WINDS FROM THE NORTHEAST TURNING LIGHT  
AND VARIABLE. LOW CONFIDENCE.  
 
OUTLOOK...  
 
FRIDAY THROUGH SATURDAY MORNING...PREDOMINANTLY VFR, BUT SCATTERED  
SHOWERS AND THUNDERSTORMS AFTER 18Z COULD RESULT IN TEMPORARY MVFR  
CONDITIONS. VARIABLE WINDS 5 KTS OR LESS BECOMING N 5 TO 10 KT. LOW  
CONFIDENCE.  
 
SATURDAY AFTERNOON THROUGH MONDAY...VFR. N AND NE WINDS 5-10 KTS  
BECOMING S AND SW ON MONDAY. HIGH CONFIDENCE.  
 

 
   
MARINE
 
 
GENERALLY SUB-SCA CONDITIONS ARE EXPECTED TODAY WITH NORTHEAST WINDS  
FROM 10 TO 15 KNOTS. A FEW GUSTS MAY EXCEED 20 KNOTS THIS AFTERNOON  
AND EVENING BUT SHOULD GENERALLY REMAIN BELOW 25 KNOTS. SEAS FROM 2  
TO 3 FEET.  
 
OUTLOOK...  
 
FRIDAY THROUGH MONDAY...WINDS AND SEAS SHOULD STAY BELOW SCA  
CRITERIA.  
 
RIP CURRENTS...  
 
WINDS TURN EAST TO EAST-SOUTHEAST THURSDAY AT 10-15 MPH WITH  
BREAKING WAVES INCREASING TO 2 TO 3 FEET. SOUTHERLY SWELL WILL SHIFT  
EASTERLY THROUGH THE MORNING. FOR NOW HELD AT A LOW RIP CURRENT  
RISK, BUT IT IS POSSIBLE SOME OF THE NEW JERSEY BEACHES MAY TREND  
TOWARDS MODERATE.  
 
WINDS WILL BE VARIABLE ON FRIDAY BUT OVERALL, ONSHORE AT 10-15 MPH.  
BREAKING WAVES WILL REMAIN 2 TO 3 FEET WITH AN EASTERLY SWELL. AGAIN  
HELD TO LOW, BUT POSSIBLE SOME NEW JERSEY BEACHES TREND TOWARDS  
MODERATE.  
 

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

 
 

 
SYNOPSIS...JOHNSON/RCM/STAARMANN  
NEAR TERM...DAVIS  
SHORT TERM...JOHNSON  
LONG TERM...WUNDERLIN  
AVIATION...DAVIS/JOHNSON  
MARINE...DAVIS/JOHNSON  
 
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