Area Forecast Discussion
Issued by NWS State College, PA

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400 FXUS61 KCTP 241910 AFDCTP Area Forecast Discussion National Weather Service State College PA 310 PM EDT Mon Apr 24 2017 .SYNOPSIS... A storm system over the southeastern states will begin to make slow progress northward along the coast over the next several days. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Rain continues to advance from the south. Showers remain scattered as lower atmosphere is fairly dry. Have tried to refine the timing and northward extent of the rain and opaque cloud cover for the near term. Overall, the timing is similar between all the guidance. QPF will be light today, on the order of a tenth of an inch or less south of I-80 and a tenth to quarter of an inch south of the turnpike. Maxes should be above normals in the north but below normal in the south. Temps through southern and central PA are in low 60s where the mainly sunny Northern portion of PA has reached the 70s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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The guidance is very consistent with timing and placement of the major features. Deep easterly flow will slide up the coast into PA through the short term period. Moisture will slowly infiltrate the lower levels and rainfall will become more widespread overnight into Tuesday morning. The confidence in occurrence of the decent rain is highest tomorrow afternoon, especially through the eastern half of the region. However, the tilt of the trough which the upper low is associated with is a little fuzzy. With a more- negative tilt it may move a little faster, and bands of rain may move more quickly. This would probably keep the rain lighter at any one location. Looking at latest plumes keep precip total/accumulation around 0.5 through the period. Most of this rain should be out of stable profiles, so thunder and big totals are not likely. Temps will be seasonably mild overnight tonight. Maxes on Tues will be homogeneous in the u50s to low 60s in the far northwest where skies will see some sun.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... The upper low is progged to take a right turn as or even before it gets to our latitude. As it pulls away to the east, the chance of rain drops off Tuesday night. It will get warm fast. It should feel like summer through the second half of the week. As the 500 hPa low fills and the attendant low moves to our northeast the chance of rain should fall off Wednesday into Wednesday evening. Our 850 hPa temperatures will rise rapidly Wednesday and it should be noticeably warmer Wednesday relative to Monday and Tuesday. Thursday into Saturday the 850 hPa temperatures will be well above normal, mainly in the 14 to 16C range and we will be on the western edge of a rather impressive early season subtropical ridge. Thursday through at least Saturday should be very warm and humid. We should have several days with high temperatures around 80. Thursday into Friday will see the passage of large upper level trough. Have left broad POPS as this trough will move a corresponding front through. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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High pressure and associated dry air mass over Pennsylvania will keep widespread VFR conditions and light winds through the afternoon over much of PA. Low pressure lifting up the east coast will spread lowering clouds and spotty light rain into southern Pa through late this afternoon. The dry air in the low levels should keep conditions VFR. However, model soundings and SREF prob charts suggest MVFR conditions will become likely by this evening across southern Pa, with IFR even possible at AOO/JST. Overnight tonight into tomorrow IFR and lower cigs are possible encroaching from the south to the north beginning around 06Z. Expect IFR possible at most TAF sites and possibly continuing into tomorrow afternoon. Outlook... Tue...Rain/low CIGs likely. Wed...AM rain/low CIGs possible. Thu...AM fog possible. PM tsra impacts possible. Fri...PM tsra impacts possible.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/Ceru SHORT TERM...Dangelo LONG TERM...Dangelo/Ceru AVIATION...Ceru/Gartner

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