824  
FXUS61 KPHI 280806  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
406 AM EDT MON JUL 28 2014  
   
SYNOPSIS
 
 
AN AREA OF LOW PRESSURE WILL MOVE OUT OF PENNSYLVANIA TONIGHT AND  
LIFT INTO NEW ENGLAND MONDAY, PULLING A COLD FRONT ACROSS THE AREA.  
HIGH PRESSURE WILL BEGIN MOVING INTO THE AREA LATER TUESDAY, AND  
REMAIN IN CONTROL OF THE WEATHER FOR THROUGH THE END OF THE UPCOMING  
WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
THE MAJORITY OF HEAVIER SHOWERS AND THUNDERSTORMS CONTINUES TO HEAD  
OFFSHORE WITH THE PASSAGE OF A STRONG MID-LEVEL IMPULSE. THERE STILL  
REMAINS ENOUGH INSTABILITY, MOSTLY CONFINED TO THE SHOWALTER LEVEL,  
FOR MORE ISOLATED TO SCATTERED SHOWERS WITH A FEW RUMBLES OF THUNDER  
THROUGH THE MORNING HOURS.  
 
THE SURFACE COLD FRONT IS STILL WELL BACK IN WESTERN PENNSYLVANIA  
AND WILL SLOWLY ADVANCE TOWARDS THE EAST THIS AFTERNOON. MID-LEVEL  
TROUGH AND ASSOCIATED COLD POOL SHOULD BE NEARBY DURING THE PEAK  
HEATING HOURS TO ALLOW FOR INSTABILITY SHOWERS, AND ISOLATED  
CONVECTION...ALSO POSSIBLE ALONG THE FRONTAL BOUNDARY. SHOULD REMAIN  
BELOW SEVERE LIMITS TODAY AS THE BEST SHEAR AND VEERING WIND  
PROFILES EXISTS TO OUR NORTH WITH THE PASSAGE OF THE CENTER OF THE  
SURFACE LOW PRESSURE. WINDS BACK TOWARDS THE WEST LATER THIS  
AFTERNOON AND BECOME GUSTY WITH A COOLER AND DRIER AIRMASS FILTERING  
IN. DAYTIME HIGHS ARE EXPECTED TO BE SEVERAL DEGREES COOLER THAN  
TODAY.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/
 
 
PRESSURE GRADIENT WILL TAKE A WHILE TO RELAX LATER TONIGHT SO NOT  
EXPECTING MUCH DECOUPLING TO OCCUR...A WEAK AND SHALLOW INVERSION  
MAY FORM ACROSS THE OUTLYING AREAS. CONTINUED MIXING SHOULD BE  
ENOUGH TO KEEP TEMPERATURES FROM FALLING OFF THE TABLE TONIGHT,  
THOUGH WITH THE COOLER AIRMASS IN PLACE CAN GIVE THE AIR  
CONDITIONERS A BREAK. BLEND OF THE MET/MAV WAS USED.  
 

 
   
LONG TERM /TUESDAY THROUGH SUNDAY/
 
 
A MOSTLY DRY START TO THE LONG TERM FORECAST, WITH PRECIPITATION  
CHANCES INCREASING LATER IN THE WEEK INTO THE WEEKEND.  
 
THERE MAY BE SOME LINGERING SHOWERS MONDAY EVENING AS THE FRONT  
CONTINUES TO PUSH OFFSHORE AND THE MID-LEVEL TROUGH LIFTS OUT, BUT  
ANY PRECIPITATION IS EXPECTED TO END BY MIDNIGHT.  
 
MUCH OF THE UPCOMING WEEK IS EXPECTED TO REMAIN MOSTLY DRY AS PW  
VALUES DROP TO AN INCH OR LOWER FOR TUESDAY AND WEDNESDAY, BUT MAY  
RETURN TO 1-1.25 INCHES FOR THURSDAY AND NEAR 1.5 INCHES FOR FRIDAY.  
HIGH PRESSURE AT THE SURFACE WILL BUILD ACROSS THE REGION, WHILE THE  
BROAD MID/UPPER TROUGH REMAINS IN PLACE ACROSS MUCH OF THE EASTERN  
HALF OF THE COUNTRY. THERE AREA NO SIGNIFICANT SHORT WAVE/VORTICITY  
IMPULSES THAT ARE FORECAST TO MOVE THROUGH FOR MUCH OF THE WEEK, BUT  
WITH THE TROUGH IN PLACE AND DAYTIME HEATING, THERE COULD BE ENOUGH  
DAYTIME INSTABILITY TO CREATE ISOLATED SHOWERS OR THUNDERSHOWERS FOR  
THE LATTER HALF OF THE WEEK. EACH DAY THE CHANCES INCREASE SLIGHTLY  
AND EXPAND IN COVERAGE. HOWEVER, WE DO NOT HAVE MORE THAN A SLIGHT  
CHANCE PROBABILITY THROUGH FRIDAY AT THIS TIME.  
 
AS WE MOVE INTO NEXT WEEKEND, WE GET A MORE SOLID RETURN OF MOISTURE  
ACROSS THE AREA AS PW VALUES REBOUND O 1.25-1.5 INCHES. WE ALSO HAVE  
A BETTER CHANCE OF VORTICITY IMPULSES AFFECTING OUR AREA WITHIN THE  
SOUTHWEST FLOW ALOFT, AND WITH THE COASTAL FRONT TRYING TO PUSH BACK  
CLOSER TO SHOWER, WE MAY HAVE A FOCUS FOR PRECIPITATION TO FORM.  
THEREFORE THE PRECIPITATION CHANCES INCREASE INTO NEXT WEEKEND.  
 
TEMPERATURES THROUGH THE EXTENDED ARE FORECAST TO BE CLOSE TO OR  
SLIGHTLY BELOW NORMAL.  
 

 
   
AVIATION /08Z MONDAY THROUGH FRIDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
THIS MORNING...EXPECTING VFR CONDITIONS TO APPROACH MVFR EARLY THIS  
MORNING BEFORE MIXING OUT SHORTLY AFTER SUNRISE. MOST OF THE SHOWERS  
AND THUNDERSTORMS ARE WELL TO OUR EAST WITH A FEW STRAY ONES ACROSS  
SOUTHERN NEW JERSEY AND CENTRAL PENNSYLVANIA. CIGS ACROSS SOUTHEAST  
PA COULD END UP BEING IFR WITH ALL THE RAIN THAT FELL LAST EVENING,  
BUT FOR THE TIME BEING DID NOT HIT THEM THAT HARD.  
 
TODAY...VFR WITH GUSTY SOUTHWEST WINDS VEERING TOWARDS THE WEST THIS  
AFTERNOON. SCATTERED TO ISOLATED SHOWERS AND A FEW RUMBLES OF  
THUNDER ARE POSSIBLE...MOSTLY NORTH AND WEST OF PHL.  
 
TONIGHT...VFR. SHOULD LOSE GUSTS BY LATE THIS EVENING BUT KEEP  
HIGHER SUSTAINED THROUGH THE OVERNIGHT HOURS WITH TIGHTER PRESSURE  
GRADIENT.  
 
OUTLOOK...  
TUESDAY-WEDNESDAY NIGHT...MAINLY VFR  
THURSDAY-FRIDAY...MAINLY VFR. ISOLATED SHOWERS/THUNDERSTORMS  
POSSIBLE BOTH AFTERNOONS, ESPECIALLY FRIDAY.  
 

 
   
MARINE
 
 
TODAY...WE CONTINUE THE SMALL CRAFT FOR ALL OUR WATERS TODAY, THOUGH  
IT MAY BE A TAD TOUGHER TO REACH THE 5 FOOT SEAS ACROSS OUR SOUTHERN  
WATERS THAN PREVIOUSLY THOUGHT. SURFACE COLD FRONT NEARS FROM THE  
WEST LATER TODAY AND WINDS SHIFT TOWARDS THE WEST-NORTHWEST. GUSTS  
ARE EXPECTED TO OCCUR AHEAD AND BEHIND THE FRONT...UPWARDS OF 25  
KNOTS...BETTER CHANCE NORTH.  
 
TONIGHT...EXTENDED THE SMALL CRAFT FOR OUR NORTHERN TWO ZONES  
THROUGH TONIGHT WHERE THE TIGHTER PRESSURE GRADIENT EXISTS AND  
BETTER VERTICAL TRANSPORT MAY STILL OCCUR. SEAS WILL TAKE A BIT  
LONGER TO COME DOWN, EVEN ONCE THE WINDS VEER TOWARDS THE WEST.  
 
OUTLOOK...  
TUESDAY-FRIDAY...SMALL CRAFT ADVISORY CONDITIONS POSSIBLE EARLY  
TUESDAY MORNING, SUBSIDING AND REMAINING BELOW ADVISORY LEVELS THROUGH  
THE PERIOD.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR  
ANZ452>455.  
SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ450-451.  
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430-  
431.  
 

 
 

 
SYNOPSIS...ROBERTSON  
NEAR TERM...HEAVENER  
SHORT TERM...HEAVENER  
LONG TERM...ROBERTSON  
AVIATION...HEAVENER/ROBERTSON  
MARINE...HEAVENER/ROBERTSON  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab PA Page
The Nexlab NJ Page
The Nexlab DE Page
The Nexlab MD Page Main Text Page