Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 272225 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 625 PM EDT SUN JUL 27 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 AM MONDAY MORNING/... TSTMS HAVE DEVELOPED ACROSS CENTRAL PA WHILE OTHER HAVE MOVED INTO WRN PA FROM OHIO. MUCH OF THE WRN AREAS WILL LIKELY BEGIN TO SEE SOME CONVECTION SHORTLY. PARTS OF THE AREA ARE BEING CONSIDERED FOR A SVR TSTM WATCH ATTM. THE TSTMS WILL HAVE A GOOD AIRMASS O FEED OFF WHILE THEY MOVE EAST. IMPROVING WINDS FIELDS WILL HELP ORGANIZATION LATER ON. HOW FAR EAST THE TSTMS GO REMAINS A QUESTION ATTM. POPS/WX UPDATED FOR THE 630 ESTF. PRODUCTS WILL BE UPDATED AGAIN IF A WATCH IS ISSUED. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... SHORT WAVES ROTATING AROUND THE ANOMALOUS STRONG 500MB TROF WILL PASS ACROSS OUR CWA ON MONDAY. CONVECTIVE TEMPS (SELF DESTRUCT SUNSHINE) WILL BE REACHED EASY AND EARLY. THE OVERALL FCST CAPE AND INSTAB ALOFT ON THE BIG THREE MODELS ARE NOT UNSTABLE ENOUGH FOR THUNDER. OTHER THAN SOME EARLY THUNDER NORTHEAST CWA, WE KEPT IT AS SHOWERS WITH HIGHEST POPS NORTHWEST THE REST OF THE DAY. STAT GUIDANCE FOR MAX TEMPS APPEARS TOO HIGH IN THE SERN CWA UNLESS THE COLD FRONT IS 2-4HRS SLOWER THAN PROGGED. WE WERE LOWER THAN GFS MOS THERE AND CLOSE TO A STAT GUIDANCE BLEND ELSEWHERE. && .LONG TERM /MONDAY NIGHT 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 /00Z MONDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 18Z TAFS HAVE A HIGH CONVECTIVE IMPACT DURING THIS EVENING INTO THE EARLY OVERNIGHT ACROSS THE TERMINALS AND AIRPORTS. REST OF THIS AFTERNOON. VFR WITH CUMULUS CLOUDS EXPANDING AND SOME CIRRUS ABOVE THEM SOUTH. NO THUNDER MENTIONED ALTHOUGH SOME ISOLATED THUNDER MIGHT FORM BEFORE THE ORGANIZED SYSTEM. LOWEST CONFIDENCE ABOUT NO THUNDER IN PA. PLEASE WATCH FOR POSSIBLE AMENDMENTS. WINDS ARE SLOWLY BACKING TO THE SOUTHWEST AND MAY EVEN GO SOUTH AT SPEEDS OF AROUND 10 KTS. THIS EVENING, EXPECTING A LINE OF STRONG TSTMS TO MOVE THROUGH THE AREA. HIGHEST CONFID AT KABE AND KRDG. LOWEST AT KMIV AND KACY. A EARLY TIMING HEDGE WAS MAINTAINED (MOST LIKELY TIME IS TOWARD THE MIDDLE OF THE TEMPO GROUP). MVFR TO BRIEFLY IFR (BECAUSE OF BREVITY NOT INCLUDED) CONDITIONS LIKELY ALONG WITH GUSTY WEST WINDS. OVERNIGHT PREVAILING MVFR CONDITIONS EXPECTED TO CONTINUE DURING SHOWERS. ISOLATED THUNDER POSSIBLE, BUT CONFIDENCE TOO LOW AS TO WHERE OR WHEN TO INCLUDE. WINDS WILL BE LIGHTER, GENERALLY FROM THE SOUTH. IMPROVEMENT TOWARD MORNING AS PCPN ENDS. THINKING TOO MUCH WIND FOR SGFCNT FOG TO FORM. MONDAY MORNING, VFR CONDITIONS WITH A CUMULUS BASED CIG OCCURRING. GUSTY WEST WINDS, ESPECIALLY FOR JULY, WITH SUSTAINED SPEEDS AROUND 15 KTS AND GUSTS TO AROUND 25 KTS. SOME WIDELY SCATTERED SHOWERS SHOULD START DEVELOPING TOWARD THE END OF THE CURRENT TAF FCST PERIOD. GREATEST CONFIDENCE NORTH, REASON FOR NOW LEFT OUT OF KPHL TAF. OUTLOOK... MONDAY NIGHT-WEDNESDAY NIGHT...MAINLY VFR THURSDAY-FRIDAY...MAINLY VFR. ISOLATED SHOWERS/THUNDERSTORMS POSSIBLE BOTH AFTERNOONS, ESPECIALLY FRIDAY. && .MARINE... A SMALL CRAFT ADVISORY WILL BE ISSUED FOR TONIGHT AND MONDAY FOR THE OCEAN WATERS. ONE WILL BE ISSUED FOR DELAWARE BAY FOR MONDAY. FIRST FOR THE LIKELIHOOD THAT SEAS REACH 5 FEET THIS EVENING AND THEN THE LIKELIHOOD OF NON CONVECTIVE WEST WIND GUSTS REACHING THE CRITERIA ON DELAWARE BAY AS WELL AS THE OCEAN WATERS DURING THE DAY ON MONDAY. WAVE WATCH GUIDANCE BRINGS SIX FOOT SEAS AS IS INTO OUR COASTAL WATERS, SHAVING A FOOT OR SO OFF WOULD STILL GET US THERE TONIGHT. TOUGH NIGHT AS IT IS WITH THUNDERSTORMS EXPECTED. ON MONDAY MORE OF THE GUSTINESS MAY BE CONCENTRATED AROUND THE INLETS AND IN DELAWARE BAY WITH POSSIBLY LESS GUSTINESS FARTHER OFFSHORE. THE GRADIENT AND WINDS SHOULD START RELAXING LATER IN THE DAY ON MONDAY. OUTLOOK... MONDAY NIGHT-FRIDAY...SMALL CRAFT ADVISORY CONDITIONS POSSIBLE EARLY MONDAY NIGHT, 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 FROM 10 PM THIS EVENING TO 6 PM EDT MONDAY FOR ANZ450>455. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT MONDAY FOR ANZ430- 431. && $$ SYNOPSIS...ROBERTSON NEAR TERM...PO SHORT TERM...GIGI LONG TERM...ROBERTSON AVIATION...GIGI/ROBERTSON MARINE...GIGI/ROBERTSON

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