Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 191442 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 942 AM EST Sun Feb 19 2017 .SYNOPSIS...
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A weakening boundary will continue to move offshore this morning, then a cold front moves south across our region tonight. High pressure will build over the Mid Atlantic through 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 this morning will continue to shift east today and gradually weaken. Another short wave is approaching New England this morning and a cold front is tied to this feature. Meanwhile, an initial cold front has weakened into a surface trough which continues to shift off of our coasts this morning. Plenty of mid level clouds remain across mostly the central and southern areas, however these are starting to thin some. More thinning is expected through the day as some subsidence occurs behind the departing feature to our south. Some sprinkles may linger a little longer across portions of eastern Maryland, Delaware and far southern New Jersey. The low-level flow is northwest today, which will add a downslope component for the coastal plain. With the exception of the far northern areas, the region started much warmer this morning compared to yesterday morning. Another warm afternoon is expected although the far north should be a bit cooler given weak cool air advection settling in (some lingering snow cover as well). Some areas, especially from the I-95 corridor on south and east, should be very close to their record high temperatures for this date. High temperatures were bumped up some especially from the I-95 corridor on south and east given a warmer start and the downslope flow component. Some cooling is noted aloft, via the 12z Sterling, VA raob, however the boundary layer remains warm. More sunshine this afternoon will contribute to even additional heating, and it should 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 needed to be increased in several areas, although these should drop a bit through the afternoon 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 /15Z SUNDAY THROUGH THURSDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of Today...VFR ceilings, 8000-10000 feet, will thin out from northwest to southeast through about 18z. Northwesterly winds around 10 knots. Some localized gusts of 15-20 knots are possible at times. Tonight...VFR overall. A few stratocumulus near 2500 feet may develop toward daybreak from about PHL on northward. North-northwest winds less than 10 knots. Monday...VFR overall. 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...
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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.
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&& .CLIMATE...
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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
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&& .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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