Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 191722 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1222 PM EST Sun Feb 19 2017 .SYNOPSIS...
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As a weakening system well to our south continues to shift offshore, a cold front will move south across our region later tonight. High pressure will build over the Mid Atlantic during Monday into Tuesday before shifting offshore. A warm front arrives early Wednesday, followed by another warm front on Friday. As a surface low lifts across the Great Lakes region, a cold front will sweep across our area on Saturday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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An upper-level low centered well to our south at midday continues to move offshore. Another short wave is sliding across northern New England this midday and a cold front is tied to this feature. A surface trough has now shifted east of our area. An area of mid level clouds continue to shift south and east and will be clearing our coastal areas by mid afternoon. Another area of high level clouds is moving southeastward and is thinning some. The low-level flow is northwest, which adds a downslope component for the coastal plain. Another warm afternoon, although the far north especially the higher elevations of the Poconos will be cooler given weak cool air advection settling in. Some record highs are expected this afternoon, and as of Noon Allentown and Wilmington have tied their record high. High temperatures were bumped up earlier for much of the region. Some cooling is noted aloft, via the 12z Sterling, VA raob, however the boundary layer remains warm. It will be warmer at the coast given enough of an offshore flow. The temperature and dew point grids were adjusted based on the latest obs, then the LAMP/LAV guidance was used initially to assist. The dew points were increased a bit, although these should drop a bit through the afternoon especially across the northwest with additional heating.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... Quiet weather is expected overnight as a northerly flow will develop across the area as high pressure will be centered to our north across Canada. A backdoor cold front will approach the area overnight and toward daybreak, so clouds may begin to increase some across the northern third of the area overnight. && .LONG TERM /MONDAY THROUGH SATURDAY/... In the wake of the back door cold front, temperatures tomorrow and Tuesday will be about 10 to 15 degrees lower than today. By the later half of Tuesday, the surface high will be shifting off shore as a pre frontal trough approaches from the west. This will set up southerly low level return flow by Tuesday afternoon. As a result, expect an increasing chance for rain showers across the region. The next warm front is expected by late Tuesday night/Wednesday morning. Stayed close to a blend of guidance at this time, but as confidence increases for an early morning warm front arrival time, may need to go above guidance for Wednesday highs as guidance continues to underestimate warm air advection events. For Thursday and Friday additional warm air advection is expected, with Thursday possibly being the warmest day of the week (assuming that the previously mentioned warm front doesn`t slide back south into our region as a cold front early Thursday). However, warming on Friday could be tempered by overcast conditions and an area of rain expanding into our region thanks to a closed surface low lifting over the Great Lakes Region. The associated cold front with this low should sweep through the region early Saturday, though there is some uncertainty with the timing. As it does so, it should bring an abrupt end to the rain. Even with the forecast strong cold air advection, temperatures over the weekend may still be slightly above normal. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This Afternoon...Areas of VFR ceilings, at or above 15000 feet, will thin out from northwest to southeast. Northwesterly winds around 10 knots. Some localized gusts to around 18 knots at times. Tonight...VFR overall. Some clouds around 2000 feet may develop toward daybreak north and west of PHL. North-northwest winds less than 10 knots. Monday...Some clouds around 2000 feet possible early north and west of PHL, otherwise VFR. North-northwest winds increase to 10-15 knots. Outlook... Monday night...VFR. Tuesday...Ceilings could lower to MVFR with rain showers continuing into Tuesday night. Wednesday and Thursday...Mostly VFR conditions are expected.
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&& .MARINE... Sub Small Craft Advisory conditions are expected across the waters today and tonight. However, wind gusts may approach Small Craft Advisory levels late tonight into Monday morning north of Little Egg, so we will continue to monitor in case an advisory is needed. Outlook... Monday...winds may gust near or above 20 kt at times, but should stay just below 25 kt. Tuesday through Thursday...winds and seas should stay below SCA criteria. && .CLIMATE... Here are the record highs for today: PHL 68-1948 ILG 67-1997 ABE 63-1997 TTN 68-1948 GED 74-1976 ACY 73-1961 RDG 67-1997 MPO 58-1981 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Gorse/Johnson Near Term...Gorse Short Term...Robertson Long Term...Johnson Aviation...Gorse/Johnson Marine...Johnson/Robertson Climate...

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