Area Forecast Discussion
Issued by NWS State College, PA

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125 FXUS61 KCTP 270237 AFDCTP Area Forecast Discussion National Weather Service State College PA 1037 PM EDT Mon Jun 26 2017 .SYNOPSIS... A long wave trough over the Great Lakes and eastern Canada will deepen across the region. This feature will keep it cooler than normal into Wednesday. Scattered showers and thunderstorms will be across the region this afternoon and evening and again on Tuesday, especially across the northern part of the Keystone state during the afternoon hours. A warm up and return of higher humidity levels will occur on Thursday and Friday, as high pressure moves off the east coast. While temperatures will average near to above normal for the second half of the week, there will be occasional showers and thunderstorms. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Showers were more widespread than expected this evening, particularly in southern extent. Shortwave trof lifting through east central PA late this evening is taking the bulk of activity with it, but will need to keep slgt chc to chc pops going until shortly past midnight in the east. Farther west, additional upstream shortwave approaching from central OH will keep isold to sct coverage of showers going overnight into my western zones. Another round of nocturnal-mid- lake-convergence-driven- convection could POP up overnight. These may reach into the Laurels/Alleghenies by morning and have kept low chc POPs there. It will be cooler tonight than Mon AM, but the varying cloud cover could help keep temps up. Some fog is possible in the valleys where they do get some rain this evening.
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Tuesday will be a similar day to Monday...but may hold a few less showers in the aftn with the negative/suppressing influence of the rising heights behind the strong short wave passing overhead (and the related cloud cover and any showers) in the morning. The afternoon heating and cool air aloft will still generate sct showers in the nrn tier. Max temps will be similar to Monday or even a few degs F cooler factoring in chaotic cloud cover in the morning. On the other hand...With the length of the daylight in late June, the sun can can overcome a late start to cook up temps.
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&& .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Trough axis moves through on Tue, with secondary trough sliding through Tue night as high pressure builds at the surface. This will keep just very low pops mentioned in the NW mtns during the evening. With clearing skies, NW flow and light winds, and dewpoints in the mid 40s to lower 50s, Wed morning will be the chilliest one of the week as lows should drop to near dewpoints. With plenty of sun, temps will rebound during the day back into the 70s. As the high moves off the east coast by Thursday, a warm front will lift across PA ushering in a southwest flow of warmer and noticeably more humid air. Lows Thu morning will be about 10F warmer than the day before, and daytime highs will bump up about 4-8F as well. Upper flow becomes zonal late week as a surface low tracks across the northern Great Lakes and southern Canada, which will focus a stationary front across that region. We`ll remain on the warm/humid side of that boundary (as highs rise to near 80 NW and 90 SE along with muggy overnight), and see convective activity increase Thu heading in the weekend - with highest likelihood over the NW. Convection will be more scattered over the SE. Active pattern continues Sun into Mon as another low rides along the persistent frontal boundary to our west and north, finally nudging that front into/through PA and keeping mention of showers in the forecast while taking some of the edge off of the above normal temps. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Scattered showers and a few tsra should die out over central Pa shortly after sunset with little chance of any restrictions. Main threat will come overnight at BFD, where wet ground combined with clearing skies and light wind could potentially result in fog. For now, am banking on just enough of a breeze to preclude significant fog issues at BFD, but will be monitoring for possible low visibilities after midnight. Elsewhere, confidence is high for widespread VFR conditions for most of the night. A weak frontal boundary will push through the region early Tuesday morning, accompanied by a few showers. Lack of moisture with this system should translate to a continuation of VFR conditions for much of central Pa. However, brief MVFR cig/vis reductions appear possible at BFD between 10Z-13Z. High pressure and associated dry air mass will build into the region later Tuesday, accompanied by widespread VFR conditions. .OUTLOOK... Wed...No sig wx expected. Thu-Fri...Isolated PM tsra impacts poss, mainly northern Pa. Sat...Scattered PM tsra impacts possible. && .EQUIPMENT... KCCX radar is back on line and in normal operation. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...Dangelo LONG TERM...RXR AVIATION...Fitzgerald EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.