Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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942 FXUS61 KPHI 201716 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 116 PM EDT Tue Jun 20 2017 .SYNOPSIS... A frontal boundary will stall off the mid- Atlantic coast this afternoon. Weak high pressure will gradually build into the region through Thursday. Summertime southwest flow around the Bermuda High looks to be re- establish by the end of the week. Another frontal system may bring showers to the forecast area over the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Partly sunny skies expected this afternoon as some cumulus clouds develop in the westerly flow over the region in the wake of the cold frontal passage early this morning. Wind gusts in the 15 to 25 mph range can also be expected through the afternoon hours...decreasing late. Maximum temperatures will still favor the 80s today. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... High and mid level clouds over the ocean may build back over parts of northeastern Maryland, Delaware and southern New Jersey tonight. Also, light showers may brush southern Delaware and the adjacent coastal waters late tonight. The sky is forecast to be mostly clear over eastern Pennsylvania and central and northern New Jersey. Another mid level short wave trough is forecast to approach our region from the west late tonight. A associated surface trough is expected to arrive around daybreak. A light southwest wind is anticipated for most of tonight. Low temperatures should be in the middle and upper 50s in the Poconos and far northern New Jersey, and in the 60s elsewhere in our forecast area. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... The overall pattern through the extended period will remain rather summerlike with temperatures at or a few degrees above normal. With this pattern it is difficult to completely rule out precip on any given day, but as of now it appears lower mid- week PoPs will increase towards the weekend as a frontal system approaches. An upper trof axis over the eastern US at mid-week will move offshore but will be followed by a couple of additional shortwave trofs over the weekend and perhaps early next week. There is disagreement in the models timing of these features and associated surface frontal systems, but a blend of models was used for the gridded forecasts. For Wednesday the forecast has low chance PoPs for southern DE and vicinity in the morning due to proximity with a lingering q-stationary frontal boundary. Then a weak upper impulse is fcst to move through the upper trof in the aftn which could trigger a few showers/t-storms in the afternoon, north/west of PHL. Otherwise most areas should remain dry. Thursday also looks dry with some weak ridging aloft. Lower level warm advection and warmer 850 mb temp should result in afternoon max temps in the mid to upper 80s. The forecast for Friday and Saturday includes a good chance for showers and t-storms. Higher PoPs will shift from N/W of PHL on Friday to S/E on Saturday as a frontal boundary slowly works its way south across the forecast area. If moisture from the tropical system now over the GlfMex becomes entrained into the frontal zone there could be some heavy rainfall, but this is very uncertain at this time. The forecast beyond Saturday depends on whether one or more frontal boundaries can push past the mid-Atlantic region or whether they stall out nearby. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Expect VFR conditions today with a westerly wind with speeds increasing to 10 to 15 knots along with gusts near 20 knots. The wind is expected to diminish back below 10 knots for tonight and the direction is forecast to change gradually to the southwest. OUTLOOK... Wednesday and Thursday...VFR conditions expected. Southwest to west winds 10 kt or less. Friday and Saturday...mostly VFR conditions but occasional MVFR or lower in scattered mainly afternoon showers and thunderstorms. South to southwest winds 10 to 15 kt. && .MARINE... The wind is forecast to favor the southwest for today and tonight around 10 to 15 knots as the cold front inches further eastward before stalling. Wave heights have fallen below 5 feet south of Cape May, so the SCA from Cape May through Fenwick Island has been cancelled. The SCA along the NJ coast will continue for a few more hours, but will probably be cancelled with the mid-afternoon update. OUTLOOK... Wednesday and Thursday... Winds and seas should remain below SCA criteria. Friday and Saturday...Winds and/or seas could approach SCA thresholds in stronger southwest flow. RIP CURRENTS... We will continue with the moderate risk for the development of dangerous rip currents for today along the coast of Delaware and New Jersey. We are expecting a 7 second southerly wind swell on top of a long period (around 13 to 15 second) southeasterly ground swell. Similar conditions are anticipated for Wednesday and perhaps into Thursday when we should begin to lose the long period southeasterly swell. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ450>453. && $$ Synopsis...AMC Near Term...Iovino/Miketta Short Term...Iovino Long Term...AMC Aviation...AMC/Iovino/Miketta Marine...AMC/Iovino/Miketta is the U.S. government's official web portal to all federal, state and local government web resources and services.