277  
FXUS61 KPHI 280959  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
559 AM EDT TUE MAR 28 2017  
   
SYNOPSIS
 
 
WEAK LOW PRESSURE WILL MOVE ACROSS THE MIDDLE ATLANTIC REGION TODAY  
AND THEN OFFSHORE TONIGHT. LARGE HIGH PRESSURE WILL BUILD ACROSS THE  
AREA WEDNESDAY AND THEN MOVE EAST OF THE AREA BY FRIDAY MORNING. A  
LOW AND ITS ASSOCIATED FRONTS WILL PUSH ACROSS OUR REGION FRIDAY AND  
REMAIN INTO SATURDAY. MORE HIGH PRESSURE WILL BE OVER THE AREA  
SUNDAY AND INTO MONDAY. ANOTHER DISTURBANCE MAY AFFECT THE AREA NEXT  
TUESDAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
6 AM ESTF: CHILLY NNJ AND A STRUGGLE TO REACH OUR FCST MAX  
TEMPS. GROUPS/BANDS OF HEAVY SHOWERS AND ISOLATED TSTMS SHOULD  
CONTINUE IN NJ TODAY AND DEVELOP INTO THE DELMARVA AND SE PA  
LATER THIS MORNING. TORRENTS OF RAIN IN STRONGER CELLS WITH  
POSSIBLY PEA SIZED HAIL AS REPORTED FROM LAWRENCEVILLE AROUND  
305AM THIS MORNING IN A CELL VIL OF ~34 AND WELL MONITORED BY  
OUR DIX MESH.  
 
DFA (NPW) CANCELLED OCEAN AND MONMOUTH WHERE RAINS MIXED OUT THE  
POOR VSBY.  
 
TODAY...MURKY AGAIN. MOSTLY CLOUDY. FOG AND SCATTERED HEAVY SHOWERS  
AND ISOLATED TSTMS, ESPECIALLY NORTH OF THE BOUNDARY THIS MORNING.  
 
POSSIBLY A STRONGER TSTM ON THE DELMARVA THIS AFTN WHERE BEST  
MLCAPE OF LESS THAN 800J. WEAK SPEED SHEAR SO SVR NOT EXPECTED.  
PWAT 1.25 SO BRIEF TORRENTS OF RAIN POSSIBLE IN ANY SHOWER.  
 
PLEASE FOLLOW LATER PHI DISCUSSIONS AND THOSE OF SPC REGARDING  
SVR POTENTIAL.  
 
FCST BASIS: 50 50 BLENDED 00Z/28 GFS/NAM MOS.TEMPS WERE MODIFIED  
DOWNWARD USING THE 2M TEMPS FROM HRRR AND NAM. NOTE..THATS MAX  
TEMPS IN THE MID TO UPPER 40S SUSSEX COUNTY, MONMOUTH AND OCEAN  
COUNTIES. GOING TO BE DIFFICULT FOR PHL TO REACH 60. MORE  
LIKELY UPPER 50S THERE.  
 
SO THE TEMPERATURE FORECAST REMAINS A CONCERN WITH THE  
PLACEMENT OF THE EASTWARD- EXTENDING WARM FRONT AGAIN A  
COMPLICATING FACTOR. ERRORS IN THESE VALUES ARE LIKELY GIVEN  
TIMING OF THE RAIN COOLING FACTOR AND WHERE SKIES MAY THIN TO  
ALLOW A LITTLE SUN.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/
 
 
ANY REMAINING SHOWERS END FROM WEST TO EAST WITH A SLIGHTLY  
FASTER MODELED END TO THE RAIN THAN 24 HOURS AGO.  
 
THERE COULD BE SOME PATCHY FOG, ESPECIALLY EARLY AT NIGHT IN  
THE STILL MOIST BOUNDARY LAYER WITH A LIGHT NORTH WIND  
INCREASING A BIT LATE AT NIGHT AND TRENDING NORTHWEST.  
 
FCST BASIS WAS A 50 50 BLEND OF THE 00Z/28 GFS/NAM MOS.  
 

 
   
LONG TERM /WEDNESDAY THROUGH MONDAY/
 
 
A RATHER STEADY PROGRESSION OF DISTURBANCES IN THE EXTENDED PERIOD  
WITH A 2 DAY (OR SO) RETURN PERIOD. FAIR WEATHER IS EXPECTED FOR  
MUCH OF WEDNESDAY AND THURSDAY AS HIGH PRESSURE ACROSS CANADA RIDGES  
SOUTHWARD ACROSS THE AREA. TEMPERATURES WILL BE CLOSE TO NORMAL WITH  
HIGHS IN THE MID/UPPER 50S SOUTH AND LOW/MID 50S NORTH. LOWS WILL BE  
IN THE MID/UPPER 30S NORTH AND LOW 40S SOUTH. IT WILL BE DRY AND  
BREEZY WEDNESDAY, BUT WITH WET GROUND CONDITIONS, FIRE WEATHER  
HAZARDS WILL PROBABLY NOT BE A BIG CONCERN.  
 
THE FIRST OF TWO DISTURBANCES IN THE LONG TERM WILL AFFECT MUCH OF  
THE AREA FOR MUCH OF FRIDAY AND SATURDAY. LOW PRESSURE WILL MOVE UP  
THE OHIO VALLEY FRIDAY AND THEN OFF THE VA TIDEWATER AREA SATURDAY.  
OUR REGION WILL REMAIN ON THE COOLER NRLY PART OF THE SYSTEM.  
OCCASIONAL SHOWERS SHOULD OCCUR MUCH OF THE TIME. DEPENDING ON WHAT  
COMPUTER MODEL, THE RAINS COULD BEGIN THU NIGHT. TEMPERATURES SHOULD  
REMAIN NEAR OR A LITTLE BELOW NORMAL THRU THE PERIOD. A COUPLE  
SNOWFLAKES ACROSS THE HIGHEST ELEVATIONS OF THE SOUTHERN POCONOS ARE  
POSSIBLE.  
 
FAIR WEATHER RETURNS OVER THE REGION FOR SUNDAY AND PERSIST INTO  
MONDAY AS HIGH PRESSURE TO THE NORTH RIDGES ACROSS THE AREA.  
TEMPERATURES WILL BE A LITTLE ABOVE NORMAL WITH UPPER 50S TO LOW 60S  
FOR HIGHS IN MOST AREAS. ANOTHER DISTURBANCE MAY APPROACH FOR TUE  
WITH THE LATEST EC MODEL HAVING A SOAKER SYSTEM ACROSS THE AREA AND  
THE GFS MUCH SLOWER WITH THE LOW AND A FAIR WEATHER DAY FOR TUE. WE  
JUST HAVE CHC POPS FOR NOW.  
 

 
   
AVIATION /10Z TUESDAY THROUGH SATURDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
TODAY...VARIABLE CONDITIONS WITH GENERAL DETERIORATION TO IFR  
CONDS IN ST/FOG BY 12Z IN THE LIGHT NORTHEAST FLOW. THE SOUTHERLY  
WINDS TAFS OF MIV AND ACY COULD REMAIN VFR MUCH OF THE DAY EXCEPT  
LOWER IN SHOWERS. THEN CONSIDERABLE DETERIORATION ACY AND MIV  
LATE TODAY WHEN THE WIND TURNS DECIDEDLY NORTHEAST.  
 
BANDS OF SHOWERS AND ISOLATED TSTMS, SOME WITH BRIEF HEAVY RAIN.  
LIGHT WIND, MOSTLY EAST OR NORTHEAST AT THE TAF LOCATIONS  
EXCEPT SOUTHEAST TO SOUTH AT KMIV AND KACY AT LEAST THIS  
MORNING.  
 
TONIGHT...MVFR/IFR CONDITIONS POSSIBLE IN SHOWERS AND FOG EARLY...  
BECOMING VFR LATE. LIGHT NORTH WINDS WILL BECOME NORTH TO NORTHWEST  
OVERNIGHT AROUND 10 KNOTS.  
 
OUTLOOK...  
 
WED/THU...VFR EXPECTED. GUSTY NORTH WINDS WED.  
FRI/SAT...LOWER CIGS/VSBYS EXPECTED. SHOWERS.  
 

 
   
MARINE
 
 
DENSE FOG ADVISORY CONTINUES FOR THE NEW JERSEY COASTAL WATERS  
NORTH OF LITTLE EGG. AREAS SOUTH MAY ALSO DEVELOP DENSE FOG  
THIS MORNING, BUT IT IS LESS CERTAIN AT THIS TIME.  
 
WINDS/SEAS WILL BE UNDER ADVISORY CRITERIA THROUGH TONIGHT.  
 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS THROUGH TODAY, WITH  
SHOWERS ENDING THIS EVENING.  
 
OUTLOOK...  
 
WED...SUB-SCA CONDITIONS.  
WED NIGHT/THU MORNING...LOW END SCA NEAR THE NJ COASTAL WATERS.  
THU AFTERNOON THRU FRI...SUB-SCA EXPECTED. SHOWERS FRI. FRI  
NIGHT THRU SAT...SCA POSSIBLE. SHOWERS.  
 

 
   
EQUIPMENT
 
 
KNEL APPEARS TO BE READING 10F TOO WARM THE PAST SEVERAL DAYS.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR ANZ450-451.  
 

 
 

 
SYNOPSIS...O'HARA  
NEAR TERM...DRAG 6A  
SHORT TERM...DRAG  
LONG TERM...O'HARA  
AVIATION...DRAG/O'HARA 6A  
MARINE...DRAG/O'HARA  
EQUIPMENT...  
 
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