Area Forecast Discussion
Issued by NWS State College, PA

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870 FXUS61 KCTP 241116 AFDCTP Area Forecast Discussion National Weather Service State College PA 716 AM 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/... Rain is advancing from the south on scheduled. 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. It may be tough to get to the m50s in the south. Have nudged the temps down there just slightly. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... The guidance is very consistent with timing and placement of the major mass features. Deep easterly flow will slide up the coast into PA through the short term period. So, confidence continues to be high that rainfall will occur through the period. However, the details on when and how heavy the rain will be is something very difficult to pin down. Will leave POPs generally under likelies in the north and far west tonight, but spread them gradually to the north and west. The confidence in occurrence of the decent rain is highest on Tuesday, and mainly to the east of UNV. 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. But, there is a wide and rather even spread seen in the SREF and GEFS precip total/accumulation plumes between a low-end of 0.10" at UNV to a max of 1.20". Most of this rain should be out of stable profiles, so thunder and big totals are not likely. A middle-of-the-road QPF forecast is on order. Temps will be seasonably mild overnight tonight. Maxes on Tues will be homogeneous in the u50s. && .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 /11Z MONDAY THROUGH FRIDAY/...
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High pressure and associated dry air mass over Pennsylvania will keep widespread VFR conditions and light winds through this morning over mouch of PA. Low pressure lifting up the east coast will spread lowering clouds and spotty light rain into southern Pa Monday. Initially, dry air in the low levels should keep conditions VFR. However, model soundings and SREF prob charts suggest MVFR conditions will become likely by Monday evening across southern Pa, with IFR even possible at AOO/JST. 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 SHORT TERM...Dangelo LONG TERM...Dangelo/Ceru AVIATION...Fitzgerald/Gartner

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