Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 301342 AFDCTP Area Forecast Discussion National Weather Service State College PA 942 AM EDT Sun Apr 30 2017 .SYNOPSIS...
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A nearly stationary front will remain just south of PA today. A strong Cold front will move across the region on Monday followed by brisk west to northwest winds and cooler air for Tuesday. Fair weather with milder temperatures will occur Wednesday under a weak ridge of high pressure. Deep moisture will flow north into the state Thursday afternoon through Friday bringing a return to inclement weather.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Meso anal shows the stalled surface front extended from southern Ohio to northern Virginia into the northern Chesapeake area early this morning. The frontal system aloft shows up nicely in the LI fields and is further north from near CLE east to just south of ERI then sharply SE down into the Laurel Highlands. This shows up spectacularly on the high resolution GOES R data with the convective clouds riding up over this elevated boundary while the cool air damming can be seen with the stable low clouds hanging tough east of the Alleghenies plateau. For today, shallow cool air damming will persist across much of the Central and Eastern, Ridge-Valley region of the state where a blend of the very cool NAM was used with the warmer NBM and previous fcst temps. Highs this afternoon will vary from the L60s across the higher terrain north and east of IPT and SEG, to the mid and upper 70s in the valleys near and to the west of state route 219 in western PA. Followed closely with a combination of the 07Z RAP and HRRR to time an expected area of showers that should blossom around 17-18Z across the western mountains and S-Central PA (over the western/southern extent of the sfc-925 mb front), then move northeast across the Central Mountains during the mid to late afternoon timeframe, before weakening toward dusk. QPF is expected to be generally a few hundredths to around one tenth of an inch on average with the usual isolated heavier amounts in the stronger convection.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Upper level ridge builds across the Mid Atlc Region Sunday Night and Monday, and a warm front will be lifting through the Ohio Valley and W PA. This weather feature will lead to continued chances for showers and even a tsra - mainly in the NW half of the area. The deep/potent upper low (centered over the OK panhandle and bringing snow to the southern High Plains and Southern Rockies), will lift NE acrs the central Plains today and tonight, reaching the Upper Glakes region late Monday night. This dominant weather feature will shoot pieces of mid-upper level energy well out ahead of it, which will act to trigger isolated showers (and perhaps a few low-topped TSRA) along the slowly northward drifting surface boundary over PA tonight through Monday morning. Temps should return/rise to very very warm levels on Monday. A strong cold front (bowed out east and then south from the approx 990 MB low over the Upper Glakes) will push east through PA Mon into Mon night, accompanied by a round of potentially potent showers and thunderstorms (likely reaching western half of CWA in the afternoon and eastern half during the evening). A narrow north/south ribbon of +3-4 sigma PWAT air along and just ahead of the cold front will support some locally heavy downpours and QPF up over one inch in some spots. SPC Day 2 outlook has ramped up the SVR threat with a SLGT RISK area painted across about the western half of the CWA for Monday afternoon and evening. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Once this front passes by much chillier air will advect into PA on cyclonic flow with a gusty NW wind and unsettled light showery weather, persisting mainly for the northern part of the state right into Wednesday. Chance for a more widespread (potentially MDT to HVY) rain arrives Thu into Fri as latest 00Z Operational GFS/EC run and their EFSs are coming into decent/converging agreement with an area of low pressure progged to develop along the southern Appalachians and the lift north-northeastward. Although this event shows some pretty strong signals (even at this long time range) for a potential, widespread 1-2 inch rainfall late in the upcoming week, A wide and varying array of models solutions has been present prior to the latest model run or two to throw some uncertainty into the mix w/respect to the specific timing and amount of showers across the CWA. Fri night and Saturday will turn windy and quite cool with isolated rain showers falling across the central mtns, while the Alleghenies experiences more numerous rain showers (and yes, maybe even the last gasp of show showers until later this fall). && .AVIATION /14Z SUNDAY THROUGH THURSDAY/...
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Southeast low-level flow has brought a blanket of MVFR ceilings from THV up into AOO and UNV. Expect these ceilings to hang tough in the range of about 2000-3500` today while most of the remainder of the flying area sees ceilings a little higher in the 3000-5000` range. BFD will uncharacteristically enjoy the best conditions with scattered clouds and VFR conditions. Short term high resolution model consensus shows scattered thunderstorms developing along the Alleghenies by mid afternoon and drifting to the east into the early evening. Used VCTS given low confidence/limited spatial coverage. Model guidance generally shows a lowering trend in conditions tonight into Monday and have followed this bringing most sites down to MVFR/IFR into early Monday morning. IFR is most likely at MDT/LNS. Outlook... Mon...Breezy. Showers/thunderstorms likely with periods of sub-VFR. A few strong-severe storms possible wrn 1/2 Monday afternoon/evening. FROPA Monday night. Tue-Wed...Breezy with a chance of showers NW. Thu...Widespread sub-VFR with rain likely.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Lambert/Gartner AVIATION...La Corte/Steinbugl

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