Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 230157 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 957 PM EDT Tue Aug 22 2017 .SYNOPSIS...
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A cold front will move into our region late tonight and slowly exit off the Delmarva coast Wednesday afternoon. Canadian high pressure builds into the region on Thursday and should continue to be the primary influence on our weather into early next week. Two low pressure systems should be near the Gulf coast states this weekend and eventually turn northeast early next week, possibly affecting our weather around Tuesday.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Severe Thunderstorm Watch 464 is in effect until midnight for all our eastern Pennsylvania counties except Delaware and Philadelphia, as well as the New Jersey counties of Sussex, Warren, Morris and Hunterdon. Showers and thunderstorms were in northern Maryland, eastern Pennsylvania and northern New Jersey around 9:45 PM. The convection will continue to progress eastward. Wind damage, hail and heavy rain have occurred in parts of eastern Pennsylvania and northwestern New Jersey. The convection is forecast to weaken overnight as conditions stabilize. The sky is expected to remain mostly cloudy with perhaps some patchy fog where any heavy rain falls. Low temperatures are anticipated to be in the middle and upper 60s in the Poconos and far northern New Jersey and in the lower and middle 70s elsewhere in our forecast area. The wind should favor the southwest and west overnight becoming northwest around daybreak with the arrival of a cold front.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Any ongoing showers and thunderstorms near the coast will slowly move eastward towards the waters through the afternoon as the cold front continues its surge eastward. Humidity should fall to more comfortable levels later in the day, more so by evening as a secondary front pushes through the region. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... 500 MB: a -2SD trough begins the long term period in the Great Lakes region, then weakens slightly as it moves into the northeast Friday- Monday. Thereafter, we will monitor the northeastward progress of what should be a split flow low of tropical origins, having moved ashore along the Gulf Coast by early next week. Temperatures: Calendar day averages Thursday...near or slightly below normal, then 2 to 6 degrees below normal daily Friday- Tuesday. Forecast basis: a 50 50 blend of 12z/22 GFS/NAM MOS was used Wednesday night-Thursday night, then the 12z/22 GFS MEXMOS was applied Friday and thereafter the 15z/22 WPC D4-8 gridded elements of max/min T, 12 hr POP 6 hrly dew/wind/sky. Wednesday night...Fair and more seasonable with light wind and possible patchy countryside fog. Thursday...Scattered light showers possible late Thursday in e PA with considerable afternoon cloudiness. Friday-Monday...High pressure shifts southeastward into the Great Lakes Thursday through Saturday,then eastward into southeastern Canada/Northeast U.S. Sunday and Monday. This expansive high will control our regional weather pattern across the Mid Atlantic during this time. The trough aloft could result in a shower north of I-78 Friday afternoon and there should be considerable cloudiness at that time. Otherwise, for now, good weather is predicted. Tuesday...WAA overrunning clouds, if not rain, from a potential tropical remnant moving northeastward from the Gulf coast. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Showers and thunderstorms will continue to move across our region through 0600Z with lingering showers anticipated late tonight into perhaps Wednesday morning. Conditions will vary between VFR and MVFR overnight with localized IFR in precipitation. Clearing and VFR conditions are expected for Wednesday. A southwest wind around 8 to 10 knots with gusts near 20 knots is expected to become west at 5 to 10 knots overnight, then northwest at 5 to 10 knots for Wednesday. Outlook... Wednesday night...VFR except possible mvfr or ifr fog patches toward dawn Thursday with nearly calm wind. Thursday 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.
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&& .MARINE...
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Strengthening southerly flow is allowing seas to gradually build, which should peak around 3 to 6 feet across the ocean waters and 3 to 4 feet across the Delaware Bay. Strongest gusts are expected this evening around 25-30 kt, and will gradually diminish overnight. Seas will gradually subside into Wednesday as a cold front moves through the area and the pressure gradient begins to subside. There will be a chance of showers and thunderstorms tonight into tomorrow afternoon. These storms may locally reduce visibility and produce wind gusts to near gale-force. Outlook... Wednesday night through Saturday...Winds and seas below SCA criteria. Sunday...For no SCA headline but chance that northeast flow will increase and cause hazardous seas to develop along the S NJ and DE coasts Sunday (5 feet). RIP CURRENTS... Wednesday... Low risk, possibly bordering moderate based on what develops this evening for residual effects carrying into Wednesday.
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&& .CLIMATE... Atlantic City and Allentown were within 2F of record today. Around 91F for a max T. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ430-431- 450>455. && $$ Synopsis...Drag Near Term...Iovino Short Term...99 Long Term...Drag Aviation...Drag/Iovino Marine...Drag/99 Climate...Drag

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