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 201343 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 943 AM EDT WED AUG 20 2014 .SYNOPSIS... LOW PRESSURE IN GREAT LAKES REGION WILL WEAKEN AS IT MOVES TO NEAR LAKE ONTARIO THURSDAY. A SECOND AREA OF LOW PRESSURE WILL DEVELOP NEAR THE CHESAPEAKE BAY THURSDAY NIGHT. HIGH PRESSURE IN EASTERN CANADA WILL BUILD DOWN ALONG THE EAST COAST LATER THIS WEEKEND INTO NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
830 AND 930 AM AFD UPDATES: MIXED CLOUDS AND SUN PROBABLY FAVORING MORE SUN. ANOTHER NICE DAY. A COMPLEX OF SHOWERS AND STORMS IN WPA/WVA ASSOCIATED WITH A MID- LVL SHORTWAVE TROUGH OUT AHEAD OF THE GREAT LAKES LOW SHOULD WEAKEN AS IT MOVES EASTWARD INTO AN INCREASINGLY STABLE AIRMASS THAT RESIDES EAST OF THE OH VLY. THIS IMPULSE IS FORECAST TO REACH CENTRAL PA BY MIDDAY AND EASTERN PA BETWEEN 18Z-00Z. THERE IS A POTENTIAL FOR ISOLATED SHOWERS TO DEVELOP AHEAD OF THE SHORTWAVE TROUGH DURING THE MID TO LATE AFTERNOON JUST OF OUR CWA. NO CHANGE IN AREAL COVERAGE FROM THE 330AM/630AM FCST. TONIGHT...HIGH PRESSURE WILL RETREAT OFF THE EASTERN SEABOARD AS THE ABOVE MENTIONED SHORTWAVE TROUGH MOVES INTO THE AREA FROM THE WEST. EXPECT SHOWERS AND PERHAPS A FEW THUNDERSTORMS WEST OF THE APPALACHIAN RIDGE. FORECAST IS CONSERVATIVE IN REGARDS TO HOW FAR EAST SHOWERS AND STORMS WERE MENTIONED AS MODELS GENERALLY SHOW CONVECTION DECAYING AS IT MOVES EASTWARD INTO A MORE STABLE AIRMASS OVER NJ/DE. CLOUDS COVER, WHICH WILL INCREASES ACROSS THE ENTIRE AREA WITH THE APPROACH OF THE TROUGH, WILL LIMIT RADIATIONAL COOLING TONIGHT. OFFICIAL MIN TEMP FORECAST SLIGHTLY WARMER THAN MOS GUIDANCE.
-- End Changed Discussion --
&& .SHORT TERM /THURSDAY/...
-- Changed Discussion --
THURSDAY...THE AREA OF LOW PRESSURE AND ASSOCIATED FRONTAL BOUNDARY TO OUR NORTHWEST WILL WEAKEN AS IT MOVES SE OUT OF THE GREAT LAKES TO NEAR LAKE ONTARIO. HOWEVER, THE MID/UPPER- LEVEL LOW WILL SWING THROUGH THE NORTHEAST AND MID- ATLANTIC THROUGH THURSDAY AND THURSDAY NIGHT. THIS WILL ALLOW FOR SHOWERS, AND WITH A FAIR AMOUNT OF INSTABILITY, SCATTERED THUNDERSTORMS TO DEVELOP AND MOVE INTO THE AREA. THERE IS NOT MUCH SHEAR OR MUCH OF A WIND FIELD, SO WE DO NOT EXPECT SEVERE WEATHER AT THIS TIME. PW 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).
-- End Changed Discussion --
&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
THE LONG TERM FORECAST STARTS OFF WITH RAIN CHANCES, BEFORE A DRYING OUT PERIOD SETS IN ACROSS THE AREA. THURSDAY NIGHT...A SECOND AREA OF SURFACE LOW PRESSURE IS FORECAST TO DEVELOP NEAR THE CHESAPEAKE BAY ALONG THE STATIONARY BOUNDARY TO OUR SOUTH. IT IS POSSIBLE THAT THIS MAY HELP KEEP A FOCUS FOR PRECIPITATION THURSDAY NIGHT, BEFORE IT SAGS TO OUR SOUTH. FOR FRIDAY INTO THE WEEKEND, THE MID/UPPER LOW WILL REMAIN TO OUR NORTHEAST, KEEPING A NORTHWEST FLOW ALOFT ACROSS OUR AREA. MEANWHILE, HIGH PRESSURE WILL BEGIN BUILDING DOWN ACROSS THE EAST COAST FROM EASTERN CANADA. BEFORE THE HIGH TAKES FULL CONTROL OF THE WEATHER, THERE WILL REMAIN A CHANCE OF SCATTERED SHOWERS FRIDAY AND SATURDAY AS THERE MAY BE A FEW SHORT WAVE/VORT MAXES THAT AFFECT THE AREA IN THE NORTHWEST FLOW ALOFT. BY SUNDAY INTO EARLY NEXT WEEK, THE SURFACE HIGH BUILDS FURTHER INTO THE MID-ATLANTIC REGION, WHICH SHOULD BRING DRY WEATHER TO THE AREA. HIGHS ARE EXPECTED TO START OUT CLOSE TO OR SLIGHTLY ABOVE NORMAL THURSDAY INTO FRIDAY, BUT AS THE HIGH BUILDS DOWN OUT OF EASTERN CANADA AND THE NORTHWEST FLOW ALOFT REMAINS ACROSS THE AREA OVER THE WEEKEND, 925/850 MB TEMPS AND THICKNESSES LOWER. THIS WILL ALLOW FOR SLIGHTLY BELOW NORMAL TEMPERATURES OVER THE WEEKEND. AS WE MOVE INTO EARLY NEXT WEEK, WE SHOULD START TO GET MORE OF A RETURN SURFACE FLOW AND RIDGING ALOFT BEGINS TO TAKE PLACE ONCE AGAIN, ALLOWING FOR REBOUNDING TEMPERATURES.
-- End Changed Discussion --
&& .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR SCT-BKN AOA 4000 FT. LIGHT SE TO S WIND. TONIGHT...VFR CIGS LIKELY. LIGHT SOUTH WIND. PROB30 GROUP FOR SHRA ADDED FOR RDG/ABE EARLY THIS EVE WHEN A DISTURBANCE MOVES THRU. THURSDAY...GENERALLY VFR CIGS. LIGHT SOUTH WIND. SCATTERED SHOWERS AND THUNDERSTORMS WHICH MAY LOWER CIGS/VSBYS TO BRIEFLY IFR CONDITIONS. OUTLOOK... THURSDAY NIGHT...GENERALLY VFR. CHANCE OF SHOWERS AND THUNDERSTORMS WHICH MAY LOWER CIGS/VSBYS. FRIDAY-SUNDAY...PERIODS OF LOW END VFR OR MVFR CIGS POSSIBLE WITH A CHANCE OF SHOWERS, ESPECIALLY FRIDAY INTO SATURDAY.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
NO MARINE RELATED HEADLINES THROUGH THURSDAY. EASTERLY WINDS BETWEEN 5-10 KT WILL BECOME SOUTHEASTERLY THIS AFTN AS HIPRES MOVES OFFSHORE. LOCALLY HIGHER WINDS TO 15 KT POSSIBLE THIS AFTN AND EVE. OUTLOOK... THURSDAY-FRIDAY NIGHT...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED. SATURDAY-SUNDAY...SEAS MAY BEGIN TO APPROACH SMALL CRAFT ADVISORY LEVELS AS A LONG FETCH DEVELOPS AROUND HIGH PRESSURE BUILDING IN FROM THE NORTHEAST OUT OF EASTERN CANADA.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG/ROBERTSON NEAR TERM...DRAG/KLEIN 943 SHORT TERM...DRAG/KLEIN 943 LONG TERM...ROBERTSON AVIATION...DRAG/KLEIN/ROBERTSON 943 MARINE...DRAG/KLEIN/ROBERTSON 943

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