Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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554 FXUS61 KPHI 231825 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 225 PM EDT Wed Aug 23 2017 .SYNOPSIS... A cold front will continue to move well south of the region tonight as high pressure begins to build in from the north and west. The high will continue to build over the region through early next week as it slowly shifts eastward, before it finally shifts offshore by mid week. Around the same time, a low pressure system will pass off the East Coast to the south. && .NEAR TERM /THROUGH TONIGHT/... 1230 PM ESTF: New 330 PM fcst of POPS/winds/temps/dews is already posted through Thursday. May adjust slightly pending receipt of the EC. Basically this fcst is a 50 50 blend of the 12z/23 GFS/NAM. Increased pops a bit on the Delmarva this afternoon to account for eastward passing showers but reduced the thunderstorm chances since the winds are northerly and general instability/lift/RH appears to project tstms to remain just s of the DE border. May need to adjust skycover a little heavier at 130PM along the srn edge of the forecast area. 1015 AM: Beach patrol conf call...presuming no phone calls on increased RC... we will continue low risk today. This afternoon...considerable cloudiness is still expected for extreme southern NJ and the Delmarva today with scattered showers sprinkles. Otherwise partly to mostly sunny north. Seasonable temps and slowly drying dewpoints. Tonight...Clearing skies and cold air advection with nearly calm wind will promote below normal temperatures across the region. The one question will be if we will see any fog development overnight. At this point, have not mentioned it in the forecast as we should also see considerable dry air advection behind the front. && .SHORT TERM /THURSDAY/... Thursday...Fair. Scattered sprinkles are still possible late in the day in e PA with considerable afternoon cloudiness. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Overall not much in the way of sensible weather for the long term forecast as strengthening confluence aloft allows surface high pressure to strengthen and build into the area. Forecast soundings suggest perhaps some cumulus development each day, then increasing onshore flow by Sunday as the high passes to the north and low pressure begins to deepen off the Southeast coast. Despite the overall drier air mass, will have to watch for coastal stratus development into early next week with increasing moisture beneath the inversion in onshore flow. Much more uncertainty exists by mid week as low pressure passes well to the south. One scenario if the low passes farther north is some light overrunning precipitation. A more concerning potential scenario to consider is how moisture from the remnants of T.C. Harvey interact with an upper trough expected to move into the area by mid week. Southwest-west flow may advect tropical moisture northeastward, and despite model forecast showing little in the way of QPF at the moment, there is certainly potential for a wet mid-late week. Have edged a little higher than deterministic guidance at this time. Both systems will need to be closely monitored in the week ahead. Temperatures will be close to or a few degrees below normal through mid week. && .AVIATION /17Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This afternoon...VFR with sct-bkn clouds aoa 5000 ft. Generally a light northwest wind with possible gusts 18 kt. Tonight...VFR clear. nearly calm wind. Thursday...VFR sct-bkn clouds aoa 5000 ft. light mostly northwest wind may sea breeze along the coast. Outlook... Thursday night through Sunday...VFR. Generally light winds from the N or NW, possibly becoming N-NE on Saturday and Sunday. small chance of a light shower vicinity KABE/KTTN/KRDG Thursday afternoon and Friday afternoon. && .MARINE... No headlines through Thursday. Northwest winds today may sea breeze later this afternoon. Winds become light north overnight and again northwest tomorrow morning before sea breezes are seemingly more likely to develop Thursday afternoon. Scattered showers, mostly light showers this afternoon s tip of NJ and the lower DE waters. Outlook... Thursday night through Saturday...Winds and seas below SCA criteria as high pressure builds across the area. Sunday through Monday...As high pressure moves north of the area then gradually eastward, onshore flow will begin to strengthen. The increasing pressure gradient and prolonged period of onshore flow will resulting in seas building to 5 ft or higher along the S NJ and DE coasts. Rip Currents... Low risk today for the formation of dangerous rip currents today as earlier elevated seas are slowly diminishing. Conditions are expected to improve (i.e. the risk should lower) through the afternoon. A northwest wind helps keep this southerly 5 second swell manageable. Outlook for Thursday through Saturday is currently indicating LOW risk. That doesn`t mean NO risk but sensible decision making for swimmers with ultimate safety, swimming within the watchful gaze of the life guards. Stay away from jetties/piers. Early next week... the risk for the formation of dangerous rip currents may increase depending on the the actual development- building of 8 second easterly swells && .CLIMATE... KABE monthly rainfall is now 8.34 inches...still ranked #12 for the month of August. The record is 13.47 inches in 2011. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...MD Near Term...Drag Short Term...Drag Long Term...MD Aviation...Drag Marine...Drag/MD Climate...

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