Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 202113 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 513 PM EDT WED AUG 20 2014 .SYNOPSIS... WEAK LOW PRESSURE WILL MOVE NORTH OF THE AREA TONIGHT AND THURSDAY. ANOTHER LOW PRESSURE SYSTEM WILL MOVE SOUTH OF THE AREA THURSDAY NIGHT THROUGH EARLY SATURDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTH LATER FRIDAY, THEN REMAIN FOR THE WEEKEND AND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A SHORT WAVE TROUGH AHEAD OF A MAIN UPPER-LEVEL TROUGH DROPPING DOWN ACROSS THE GREAT LAKES REGION WILL LIFT EAST-NORTHEASTWARD THROUGH TONIGHT. THE INITIAL LINE OF SHOWERS AND THUNDERSTORMS WITH THIS FEATURE CONTINUES TO WEAKEN AND FRAGMENT AS IT ENTERS OUR FAR WESTERN ZONES. THIS SHOULD CONTINUE AS IT ENCOUNTERS A MORE STABLE AIRMASS WITH AN EASTWARD EXTENT AND ALSO LESS MOISTURE. THERE IS SOME AIRMASS RECOVERY OCCURRING TO THE WEST OF THE LINE AND AN ANALYSIS SHOWED DEEPER MOISTURE FARTHER TO THE WEST. WHILE SOME SHOWERS /PERHAPS A RUMBLE OF THUNDER/ SHOULD MAKE THEIR WAY TO THE EAST TONIGHT ESPECIALLY ACROSS PORTIONS OF EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY, THEY SHOULD BE WEAKER. WE WILL MONITOR RADAR TRENDS AND ADJUST THE POPS ACCORDINGLY. IN ADDITION, SOME THUNDERSTORMS ARE DEVELOPING NEAR WASHINGTON DC HOWEVER THIS IN WITHIN AN AREA OF HIGHER INSTABILITY. OTHERWISE, ENOUGH MOISTURE AND THE LEFTOVER DEBRIS CLOUDS SHOULD RESULT IN MORE CLOUDINESS THROUGH THE NIGHT ESPECIALLY EAST AND SOUTH WHERE THE SKY HAS CLEARED THUS FAR. THE HOURLY GRIDS WERE TWEAKED BASED ON THE LATEST OBSERVATIONS AND THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN TO HELP ASSIST WITH TRENDS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... THURSDAY...ANOTHER SHORT WAVE IN THE WNW FLOW OVER SOUTHERN NEW YORK STATE SHOULD REDEVELOP HEAVY CONVECTION DURING THE AFTN OVER E PA...POSSIBLY EXTENDING INTO W NJ AND THE MD E SHORE CLOSER TO THE CONVERGENCE OF THE SFC LOW AND INVERTED TROUGH EXTENDING NWD FROM THE VCNTY OF DCA. PWAT VALUES ARE GENERALLY FORECAST AROUND 1.5-1.75 INCHES, SO SOME SHOWERS/STORMS COULD PRODUCE A PERIOD OF MODERATE TO HEAVY RAINFALL. ISOLATED SMALL HAIL NOT IMPOSSIBLE AS TT NEAR 50 IN AREA OF MAX INSTABILITY IN NJ (NEAR THE DELAWARE RIVER). FORECAST BASIS: POPS WERE BLENDED NCEP MOS POPS WITH THE 09Z SREF AND THAT GIVES THE BEST CHANCE FOR SOME NEEDED RAIN TO E PA. OTRW A 50 50 BLEND OF 12Z/20 NCEP MOS EXCEPT BLENDED RGEM SKY WITH NAM SKY AND GFS MOS GUIDE. NEAR OR SLIGHTLY ABOVE NORMAL TEMPS. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... THE LONG TERM FORECAST STARTS OFF WITH RAIN CHANCES, BEFORE A DRYING OUT PERIOD SETS IN ACROSS THE AREA. THE WEAK AREAS OF LOW PRESSURE TO THE NORTH (THU NIGHT AND FRIDAY) AND THE SOUTH (FRIDAY THRU SATURDAY) WILL FORCE US TO KEEP LOW CHC POPS OR SLGT CHC POPS FOR THOSE PERIODS. THE SYSTEMS DO NOT LOOK STRONG ENOUGH TO PRODUCE ANY HEAVY RAINS HOWEVER. DRY WEATHER IS EXPECTED FOR SUNDAY INTO EARLY NEXT WEEK. HIGH PRESSURE WILL BUILD IN FROM THE NORTH/NORTHEAST ALLOWING DRY AIR TO OVERSPREAD THE AREA. TEMPERATURES THROUGH THE LONG RANGE WILL START NEAR NORMAL FRIDAY...BEFORE DROPPING TO BELOW NORMAL FOR THE WEEKEND AND NEXT MONDAY. READINGS WILL REBOUND BACK TO NEAR NORMAL NEXT TUESDAY AND THEN POSSIBLY GO ABOVE NORMAL WEDNESDAY. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TONIGHT...VFR CEILINGS AT OR ABOVE 4000 FEET SPREADING FROM WEST TO EAST. SOME SHOWERS SHOULD BE AROUND MAINLY NORTH AND WEST OF KPHL. LIGHT SOUTHERLY WINDS. THERE COULD BE SOME LOCALIZED MVFR CEILINGS WITH FOG TOWARD DAYBREAK. THURSDAY...GENERALLY VFR CEILINGS. SOME SHOWERS AND THUNDERSTORMS ARE EXPECTED TO OCCUR ESPECIALLY FARTHER INLAND, WHICH MAY LOWER CEILINGS AND VISIBILITIES TO BRIEFLY IFR. SOUTHERLY WINDS GENERALLY 5-10 KNOTS. OUTLOOK... THU NIGHT THRU SATURDAY...MOSTLY VFR. SHOWERS WITH LOWER CONDITIONS ARE POSSIBLE. SAT NIGHT THRU MONDAY...MOSTLY VFR. && .MARINE... NO MARINE RELATED HEADLINES THROUGH THURSDAY. EAST-SOUTHEAST WINDS BETWEEN 5-15 KT. OUTLOOK... THU NIGHT THRU FRI NIGHT...SUB SCA CONDITIONS W/ SCT SHOWERS. SAT THRU MON...LOW END SCA SEAS EXPECTED ON THE OCEAN. MOSTLY FAIR WX. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...O`HARA NEAR TERM...GORSE SHORT TERM...DRAG LONG TERM...O`HARA AVIATION...DRAG/GORSE/O`HARA MARINE...DRAG/O`HARA

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.