Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 220333 AFDCTP Area Forecast Discussion National Weather Service State College PA 1133 PM EDT Sun May 21 2017 .SYNOPSIS... A cold front will push east from the Ohio Valley and pass through PA on Monday. An unsettled week is then in store with an active weather pattern across the entire U.S. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Several light broken lines of showers crossing the Alleghenies and Central Mountains this evening...generally along and east of 35 to 40 kt 850 mb jet and elongated shearing upper trof crossing the region. The showers are butting into the western periphery of sharp upper ridge located just east of the region...with showers aided by deep layer moisture (1.25" to 1.5" PW). Rainfall amounts will continue to be light overnight... and generally will not eclipse a quarter inch in most places. Still could be a rumble of thunder over mainly northern portions of the Alleghenies where forcing and moisture are maximized. Trailing shortwave acting on residual moderate deep layer moisture will keep shower chances going through the pre dawn hours. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... Cold front is more dragged thru the area rather than pushed through as the upper trough and sfc low are far away. Pressure barely dips and does not reach 1012mb along the frontal trough. Wind should not be strong, even as the mixing of the day behind the main rain plume goes to the east and the front follows later. Have kept mention of thunder on Monday to just the far eastern section of the CWA. Again, rainfall looks beneficial, and not heavy at all. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... Chance of a shower in the east Mon eve, then a weak area of high pressure will build in for Mon night into Tuesday - with a cooler morning and maybe some patchy fog in store. Wave slides up the east coast on Tue, which will bring chances for rain mainly to the SE later in the day. That will mark beginning of an extended unsettled weather pattern that will linger into the weekend, as an upper-level low drops into the Great Lakes and surface low pressure develops over the Mid- Atlantic region. Light showers will begin to work in from the SW Tue night into Wed, with the dreariest and wettest day being Thursday as a soaking rain looks likely with an occluded front moving through. The synoptic system will be lifting out by Friday, allowing conditions to slowly improve from the SW. Light showers or drizzle may linger as weak surface ridge tries to work in under retreating cool pool aloft. Sat should bring a return of brighter skies, albeit briefly, because clouds increase for the second half of the weekend along an old and sharpening frontal boundary extending from the mid atlantic region westward into the Ohio Valley. This boundary will bring potential for return of showers by Sun and Mon. && .AVIATION /04Z MONDAY THROUGH FRIDAY/...
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The first batch rain ahead of the cold front fell apart of central PA. Mostly VFR with patch MVFR this evening. Some areas of IFR possible overnight and Monday. There is still a chance for rain and lowered ceilings in the 0900 to 1600 UTC range over much of the southeastern areas. A wave is forecast to come up the boundary as it tries to push across PA. This could bring some rain and lowered ceilings. Most models show the westerly flow and drier air into western areas in the 15-16Z window and into central areas around 17Z. Westerly winds should move across the entire region by about 18Z which should lead to improved conditions in the eastern areas (KTHV,KCXY,KMDT,KLNS) in the afternoon hours. Better conditions in the west spreading east is the theme. Most areas should be VFR by 16-19Z even in the east. Improving conditions Monday night. But the models imply rain approaching our region Tuesday afternoon/eve. .OUTLOOK... Tue...Rain/log cigs possible by evening mainly E/SE. Wed...SCT SHRA poss - mainly W. Thu-Fri...SHRA/low cigs NW, Mainly VFR SE.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...DeVoir/Lambert LONG TERM...Lambert/RXR AVIATION...Grumm

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