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 010323 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1123 PM EDT SUN AUG 31 2014 .SYNOPSIS... HIGH PRESSURE WELL OFF THE EAST COAST WILL MAINTAIN A SOUTHWESTERLY FLOW OVER THE AREA THROUGH THE FIRST PART OF THE WEEK. A WEAK COLD FRONT IS THEN EXPECTED TO MOVE ACROSS OUR AREA LATE TUESDAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR THE SECOND HALF OF THE WEEK BEFORE ANOTHER COLD FRONT ARRIVES IN THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A TRAILING SHORT WAVE ACROSS THE DELMARVA WILL KEEP CONVECTION GOING FOR AWHILE AS ENOUGH INSTABILITY REMAINS WITHIN A WARM AND HUMID AIRMASS. THERE MAY NOT BE MUCH LIGHTNING AS THE INSTABILITY HAS WANED COMPARED TO EARLIER, WITH THE EXCEPTION OF PORTIONS OF MARYLAND AND DELAWARE. HOWEVER, DOWNPOURS WILL OCCUR GIVEN THE HIGH MOISTURE LADEN AIR IN PLACE /2.2 INCHES OF PW VIA THE 00Z STERLING, VA RAOB/. THE HIGHEST POPS REMAIN ACROSS THE SOUTHERN ZONES GIVEN THE SHORT WAVE TRACK. FARTHER NORTH AND WEST, SOME SHOWERS WILL STILL OCCUR ESPECIALLY IN SOUTHEASTERN PENNSYLVANIA HOWEVER THE COVERAGE IS LESS CERTAIN AND THEREFORE LOWER POPS WERE MAINTAINED. WE ARE ANTICIPATING A DECENT AMOUNT OF CLOUDS TO REMAIN ACROSS THE AREA THROUGH THE NIGHT, THEREFORE WHILE SOME FOG CAN FORM IT DOES NOT APPEAR TO BE WIDESPREAD ATTM. 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 MONDAY MORNING THROUGH 6 PM MONDAY/... SOUPY AIRMASS REMAINS IN PLACE WITH WEAK MID-LEVEL SHORTWAVE MOVING THROUGH. THE WAVE ALOFT LOOKS TO GET SHEARED OUT AS IT MOVES IN ALOFT SO IT DOES NOT APPEAR TO BE A GREAT TRIGGER FOR CONTINUED CONVECTIVE ACTIVITY. THAT BEING SAID, ANY DIFFERENTIAL HEATING THAT OCCURS COMBINED WITH WEAK SURFACE CONVERGENCE CAN BE THE SPARK NEEDED TO GET CONVECTION GOING. WE CONTINUE TO HAVE AT LEAST 40-50 PERCENT POPS FOR A MAJORITY OF THE REGION. TEMPERATURES TOMORROW WILL BE SEVERAL DEGREES ABOVE NORMAL. UPTICKED THE MAX TEMPERATURES A DEGREE ACROSS THE I-95 CORRIDOR AS ANY BREAKS IN THE CLOUDS WILL BE ENOUGH FOR SUBSTANTIAL HEATING. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... AT THE BEGINNING OF THIS PERIOD, WE SEE A TRANSITION TO MOSTLY ZONAL FLOW FROM THE LOWER THROUGH UPPER LEVELS. TUESDAY...BEFORE MUCH DRY AIR ADVECTION WITH THE ZONAL FLOW CAN KICK IN THOUGH, WE WILL SEE A RATHER UNCOMFORTABLE DAY WITH HIGHS IN THE 80S AND 90S, WHILE HEAT INDEX VALUES COULD APPROACH THE MID AND UPPER 90S IN DELMARVA AND THE I95 CORRIDOR. TUESDAY NIGHT...MODELS STILL SHOWING THE FRONT ARRIVING DURING THIS PERIOD, BRINGING SOMEWHAT COOLER, BUT MOSTLY DRIER AIR. STILL SOME CHANCE FOR SHOWERS AND STORMS AHEAD OF AND WITH THE FRONT, HOWEVER WITH THE ZONAL FLOW IN PLACE, AND MODEST DRY AIR ADVECTION OCCURRING AHEAD OF THE FRONT, MOISTURE AVAILABILITY WILL BE SOMEWHAT QUESTIONABLE. WEDNESDAY THROUGH FRIDAY...A HIGH BUILDS OVER THE REGION IN THE WAKE OF THE COLD FRONT. AS A RESULT EXPECT A FEW, NICE, SUMMER LIKE DAYS WITH HIGHS IN THE 80S. SATURDAY THROUGH SUNDAY...THE NEXT COLD FRONT IS SET TO ARRIVE OVER THE WEEKEND. THOUGH THERE IS SOME QUESTION WITH THE CONTINUED ZONAL FLOW HOW FAR SOUTH THE FRONT WILL DIG, BOTH THE GFS AND ECMWF HAVE BEEN CONSISTENT IN SHOWING THE FRONT MOVING SOUTH OF OUR REGION THROUGH THIS PERIOD. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. OVERNIGHT...MOSTLY VFR TO MVFR. LOWER CONFIDENCE REGARDING WIDESPREAD MVFR CEILINGS AS WE MAY END UP WITH MORE LIGHT FOG OVERNIGHT, ESPECIALLY WHERE RAIN FELL. SOME SHOWERS AND A FEW THUNDERSTORM WILL CONTINUE, ESPECIALLY FROM THE KPHL METRO ON SOUTH AND EASTWARD. TO THE NORTH AND WEST OF HERE, THERE REMAINS THE POTENTIAL FOR SOME SHOWERS. DOWNPOURS WILL GREATLY REDUCE THE LOCAL VISIBILITY FOR A BRIEF TIME. THE WINDS LESSEN AND MAY BECOME VARIABLE AT MANY TERMINALS, HOWEVER THEY SHOULD REMAIN MOSTLY SOUTH-SOUTHWESTERLY WHERE THERE IS A DIRECTION. MONDAY...ANY STRATUS/FOG MIXES OUT BY LATE MORNING, OTHERWISE VFR. SOME SHOWERS AND THUNDERSTORMS ARE ANTICIPATED ESPECIALLY FROM MIDDAY ON, HOWEVER THE LOCATION IS IN QUESTION SO ONLY INCLUDED -SHRA IN THE AFTERNOON TIME PERIOD. OUTLOOK... MONDAY NIGHT...COVERAGE OF STORMS DECREASES THROUGH THE EVENING HOURS. HOWEVER, WITH LOW LEVEL MOISTURE IN PLACE, IFR VISIBILITIES DUE TO BR COULD LINGER FOR MUCH OF THE NIGHT. TUESDAY AND TUESDAY NIGHT...CONDITIONS IMPROVING TO VFR EARLY IN THE DAY. SOME SHOWERS AND THUNDERSTORMS POSSIBLE LATE TUESDAY AFTERNOON AND TUESDAY EVENING, ALONG WITH AN ABRUPT WIND SHIFT AS A COLD FRONT MOVES THROUGH THE REGION. WEDNESDAY THROUGH FRIDAY...GENERALLY VFR CONDITIONS EXPECTED. && .MARINE... SUB-SCA CONDITIONS EXPECTED TONIGHT AND TOMORROW. SEAS WILL CONTINUE TO BUILD THROUGH TOMORROW...AROUND 4 FEET. WINDS SHOULD BE LIGHTER TOMORROW THAN TODAY. OUTLOOK... MONDAY NIGHT THROUGH FRIDAY...SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA. SOME GUSTY WINDS WILL BE POSSIBLE IN THE VICINITY OF THUNDERSTORMS MONDAY EVENING AND AGAIN TUESDAY NIGHT. && .HYDROLOGY... VERY HIGH PWAT AIRMASS IN PLACE TONIGHT, AND AT LEAST ANOTHER SHORT WAVE TRAVERSING THE AREA MAINLY ACROSS THE SOUTHERN ZONES. THIS WILL ALLOW FOR VERY HEAVY DOWNPOURS. STORM MOTIONS SHOULD BE QUICK ENOUGH FOR MOSTLY POOR DRAINAGE FLOODING. THROUGH MONDAY AFTERNOON, WHEN MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE, QPF OF AROUND AN INCH ARE POSSIBLE, HIGHER WITHIN SOME STORMS. CURRENT CONDITIONS ACROSS THE REGION HAVE BEEN DRY SO NOT EXPECTING MUCH IN THE WAY OF FLASH FLOODING CONCERNS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...JOHNSON NEAR TERM...GORSE SHORT TERM...HEAVENER LONG TERM...JOHNSON AVIATION...GORSE/HEAVENER/JOHNSON/ROBERTSON MARINE...HEAVENER/JOHNSON HYDROLOGY...

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