005  
FXUS61 KPHI 152208  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
608 PM EDT MON JUL 15 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BUILD OFFSHORE TONIGHT. A WEAK WARM FRONT LIFTS  
NORTH ON TUESDAY, AND THEN THE REMNANTS OF BARRY WILL AFFECT THE  
REGION WEDNESDAY NIGHT INTO THURSDAY. A COUPLE WEAK AND DRY COLD  
FRONTS WILL PASS NEAR THE REGION OVER THE WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
 
 
630 PM...WITH THE CURRENT FORECAST ON TRACK, MADE ONLY VERY  
MINOR ADJUSTMENTS TO THE TEMPERATURE/DEWPOINT TEMPERATURE GRIDS  
TO MATCH CURRENT OBSERVATIONS. HIGH PRESSURE WILL MAINTAIN  
CONTROL OVER THE AREA THROUGH TONIGHT BRINGING MAINLY CLEAR  
SKIES, LIGHT WINDS, SEASONABLE TEMPERATURES, AND FAIRLY  
COMFORTABLE HUMIDITY LEVELS. BY LATER TONIGHT EXPECT LOWS MAINLY  
IN THE 60S...RANGING FROM AROUND 60 OVER THE SOUTHERN POCONOS  
TO THE UPPER 60S TO AROUND 70 IN THE URBAN CORRIDOR.  
 

 
   
SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/
 
 
HIGH PRESSURE WILL WEAKEN OVER THE AREA TUESDAY AS ITS CENTER  
SHIFTS OFFSHORE. THIS WILL ALLOW A LIGHT SW FLOW TO SET UP WITH  
BOTH TEMPERATURES AND HUMIDITY LEVELS STARTING TO CREEP UP A BIT  
COMPARED TO MONDAY. HIGHS SHOULD BE MAINLY IN THE UPPER 80S TO  
LOW 90S EXCEPT A BIT COOLER RIGHT ALONG THE COAST AS WELL AS THE  
SOUTHERN POCONOS. SKIES WILL BE MAINLY CLEAR WITH JUST SOME  
SCATTERED CU DEVELOPING IN THE AFTERNOON AND SOME HIGH CLOUDS  
MOVING IN FROM THE WEST LATE DAY. THERE'S THE OUTSIDE CHANCE OF  
SOME ISOLATED LATE DAY SHOWERS/STORMS OVER PARTS OF EASTERN PA  
INTO THE DELMARVA BUT FORCING AND DEEP MOISTURE WILL BE LIMITED  
SO WE KEPT POPS AT 20 PERCENT OR LOWER.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
 
 
OVERVIEW: REMNANTS OF BARRY WILL MOVE THROUGH THE REGION  
WEDNESDAY NIGHT AND THURSDAY FOLLOWED BY A PERIOD OF EXCESSIVELY  
HOT WEATHER ACROSS THE MID-ATLANTIC.  
 
WEDNESDAY...THE HOT AND HUMID AIR RETURNS TO THE MID-ATLANTIC AS THE  
REMNANTS OF BARRY MAKE THEIR WAY TOWARDS THE REGION. STRONG MOISTURE  
ADVECTION IN THE DEEPENING SOUTH TO SOUTHWEST FLOW WILL RAISE THE  
DEW POINTS BACK UP INTO THE LOW TO MID 70S GIVING US THAT GROSS  
STICKY FEELING. HIGH TEMPERATURES WILL AGAIN RISE INTO THE LOWER 90S  
THROUGH MUCH OF THE REGION. HEAT INDEX VALUES WILL RISE, ESPECIALLY  
THROUGH THE URBAN CORRIDOR, WITH MANY AREAS SEEING VALUES AROUND 100-  
105. WITH INCREASING MOISTURE AND GROWING INSTABILITY, WE SHOULD SEE  
SOME THUNDERSTORMS DEVELOP THROUGH THE AFTERNOON AND WITH PWATS IN  
EXCESS OF 2.0", TORRENTIAL RAINFALL WILL BE A CONCERN. EXPECT THE  
SHOWERS AND THUNDERSTORMS TO CONTINUE INTO WEDNESDAY NIGHT WITH  
LITTLE RELIEF TEMPERATUREWISE WITH EXTENSIVE CLOUD COVER AND LOWS  
REMAINING IN THE 70S.  
 
THURSDAY...HEAVY RAIN CONTINUES AS THE REMNANT LOW FROM BARRY MOVES  
ACROSS THE REGION. DUE TO EXTENSIVE CLOUD COVER ACROSS THE REGION,  
WE WON'T WARM AS EFFICIENTLY AS WE DO ON WEDNESDAY SO EXPECT HIGHS  
TO BE A FEW DEGREES COOLER. UNFORTUNATELY, THE DEW POINTS REMAIN IN  
THE 70S SO THE MUGGINESS WILL REMAIN AND HEAT INDEX VALUES WILL  
LIKELY RISE BACK TO AROUND 100. AGAIN, OVERNIGHT LOWS WILL REMAIN UP  
AND IN THE LOW TO MID 70S.  
 
FRIDAY THROUGH SUNDAY...THE HEAT IS ON AND WILL CONTINUE THROUGH THE  
WEEKEND. SURFACE HIGH PRESSURE WILL SITUATE ITSELF OVER THE WESTERN  
ATLANTIC WITH A SURFACE TROUGH ACROSS THE EASTERN SEABOARD. IN THE  
MID AND UPPER LEVELS, WE WILL SEE A LARGE RIDGE SPREAD ACROSS THE  
MID-ATLANTIC, WHICH WILL HELP IN FACILITATING AN INCREASINGLY HOT  
AIRMASS THROUGH THE WEEKEND. WHILE THE NUMBERS MAY VARY ACROSS THE  
MODELS, THE 850MB TEMPERATURES LOOK TO RISE AROUND 22-23C EACH DAY,  
WHICH TRANSLATES TO UPPER 90S TO AROUND 100 DEGREES AT THE SURFACE,  
ESPECIALLY FOR FRIDAY AND SATURDAY. WITH DEW POINTS IN THE MID TO  
UPPER 70S, IT WILL FEEL OPPRESSIVE AND IT IS LOOKING INCREASINGLY  
LIKELY THAT HEAT HEADLINES WILL BE NEEDED FOR THIS PERIOD. OVERNIGHT  
LOWS WILL REMAIN IN THE UPPER 70S TO AROUND 80, ESPECIALLY THROUGH  
THE URBAN CORRIDOR, PROVIDING NO RELIEF FROM THE HEAT. THE HEAT  
STARTS TO BREAK A BIT FOR SUNDAY AS THE UPPER/MID RIDGE STARTS TO  
SHIFT TOWARDS THE EAST BUT BOTH THE GFS AND ECMWF HOLD ONTO THE  
HIGHER 850MB VALUES THROUGH SUNDAY SO ANTICIPATE THAT THE EXCESSIVE  
HEAT WILL CONTINUE THROUGH THE END OF THE WEEKEND. ADDITIONALLY, WE  
MAY GET BRIEF RELIEF FROM SHOWERS AND THUNDERSTORMS THROUGH EACH  
AFTERNOON/EVENING AS THE AIRMASS REMAINS FAIRLY UNSTABLE AND  
EXCEPTIONALLY MOIST. THE MISSING FACTOR IS THE TRIGGER AND THERE  
JUST MAY BE ENOUGH LIFT ALONG THE SURFACE TROUGH TO GET US GOING  
EACH DAY. THE CONVECTION WILL LARGELY BE DIURNALLY DRIVEN SO AS WE  
HEAD PAST SUNSET EACH NIGHT, IT SHOULD DIMINISH IN COVERAGE. WITH  
SUCH EXCESSIVE MOISTURE ACROSS THE REGION YOU CAN EXPECT THAT AND  
SHOWER OR THUNDERSTORM THAT DEVELOPS WILL HAVE TORRENTIAL RAINFALL.  
 
MONDAY...THE HEAT MAY FINALLY BREAK SOME FOR MONDAY AS THE MODELS  
ARE SHOWING THE UPPER/MID RIGHT SHIFTING TO THE EAST AND A WEAK  
BOUNDARY PUSHING IN FROM THE WEST. A SHIFT TO A MORE NORTHWESTERLY  
FLOW, ALBEIT WEAK, MAY BE ENOUGH TO CUT THE HUMIDITY LEVELS AND DROP  
THE HEAT INDEX VALUES BACK DOWN TO THE UPPER 90S TO AROUND 100.  
 

 
   
AVIATION /22Z MONDAY THROUGH SATURDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
THIS AFTERNOON...VFR/SKC-FEW250. WINDS MAINLY W- SW 5-10 KT  
EXCEPT AFTERNOON SEA BREEZES WILL RESULT IN S- SE WINDS AT KACY  
AND POSSIBLY KMIV.  
 
TONIGHT...VFR/SKC. LGT/VRB WINDS.  
 
TUESDAY...MOSTLY VFR CONDITIONS, WITH A SLIGHT CHANCE FOR  
AFTERNOON SHOWERS AND THUNDERSTORMS AT RDG AND ABE.  
SOUTHWESTERLY WINDS 5 TO 10 KT.  
 
OUTLOOK...  
 
WEDNESDAY...MAINLY VFR CONDITIONS EXPECTED. MVFR OR LOWER IN SHOWERS  
AND THUNDERSTORMS. SOUTH TO SOUTHWEST WINDS AROUND 5 TO 10 KNOTS.  
 
THURSDAY...MVFR OR LOWER IN SHOWERS AND THUNDERSTORMS WITH PERIODS  
OF VFR POSSIBLE. SOUTH TO SOUTHWEST WINDS AROUND 5 TO 10 KNOTS.  
 
FRIDAY AND SATURDAY...MAINLY VFR CONDITIONS EXPECTED. MVFR OR LOWER  
POSSIBLE IN SHOWERS AND THUNDERSTORMS, MAINLY DURING THE  
AFTERNOON/EVENING. WEST TO SOUTHWEST WINDS AROUND 5 TO 10 KNOTS.  
EXCESSIVE HEAT INDEX VALUES EXPECTED.  
 

 
   
MARINE
 
 
THROUGH TONIGHT...SUB-SCA CONDITIONS. WINDS MAINLY S/SE THIS  
AFTERNOON AROUND 10 KNOTS OR LESS BECOMING SOUTHWEST TONIGHT.  
SEAS 2-3 FEET ON THE OCEAN AND 1-2 FEET ON DE BAY.  
 
TUESDAY...SUB-SCA CONDITIONS CONTINUING WITH SW WINDS 5-10 KNOTS  
BECOMING SOUTHERLY 10-15 KNOTS BY LATE DAY. SEAS REMAIN AROUND 2  
FT.  
 
OUTLOOK...  
 
WEDNESDAY AND THURSDAY...SUB-SCA CONDITIONS EXPECTED. SOUTH TO  
SOUTHWEST WINDS AROUND 10 TO 15 KNOTS. SEAS AROUND 2 TO 4 FEET.  
 
FRIDAY AND SATURDAY... SUB-SCA CONDITIONS EXPECTED. SOUTHWEST WINDS  
AROUND 10 TO 15 KNOTS. SEAS AROUND 2 TO 3 FEET.  
 
RIP CURRENTS...  
THERE IS A LOW RISK FOR THE DEVELOPMENT OF DANGEROUS RIP CURRENTS AT  
NEW JERSEY AND DELAWARE BEACHES TODAY.  
 

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

 
 

 
SYNOPSIS...JOHNSON  
NEAR TERM...FITZSIMMONS/MIKETTA  
SHORT TERM...FITZSIMMONS  
LONG TERM...MEOLA  
AVIATION...FITZSIMMONS/MEOLA  
MARINE...FITZSIMMONS/MEOLA  
 
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