Area Forecast Discussion
Issued by NWS State College, PA

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230 FXUS61 KCTP 181041 AFDCTP Area Forecast Discussion National Weather Service State College PA 641 AM EDT Fri Aug 18 2017 .SYNOPSIS... A cold front will move through the region today. After a brief cool down, warmer air will return Monday into Tuesday as a ridge builds aloft. Another cold front should trigger showers around mid-week and the week should end on a cooler note. && .NEAR TERM /THROUGH TONIGHT/... Showers continue to stream across much of the Central and Northern Mountains. RAP indicates instability has waned and it`s been a while since we have seen any lightning in our CWA. Ultimately the cold front, currently moving into central OHIO, will push through the region. Consensus timing suggests the front entering the Central Mountains by around mid day, and finally clearing my SERN zones around or shortly after 00Z/8PM. Models develop a fair amount of instability and shear in the warm air east of the front this afternoon, with SPC painting my far SERN zones in a Slight Risk. The main threat should be strong wind gusts and isolated supercells. Bufkit shows tall skinny Capes so the threat for hail doesn`t look very impressive. With the front passing off to the east this evening, the bulk of the overnight hours will be dry, with the best chance for a lingering shower after dark being over the far eastern areas. Cooler and drier air will seep in overnight. Lows will drop back into the upper 50s to mid 60s. && .SHORT TERM /SATURDAY/... High pressure will nose into the state to start the day with fair-dry conditions. However a potent shortwave rotating around the upper low over Hudson`s Bay will bring a renewed threat for scattered showers back into the forecast area during the afternoon. If it were winter, we would call it an Alberta Clipper. Saturday`s highs will range from the mid 70s north to mid 80s south which will average a couple of deg either side of normal. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... After the shortwave moves through the area by later Saturday, heights aloft are forecast to rise and become quasi-zonal. Sunday into Tuesday looks warm and dry, with Tuesday even ending up hot over most of the area. A new shortwave moving through SRN Canada will an bring an increasing chance for rain, possibly as early as Tuesday afternoon over western sections of the forecast area. There are differences in timing of the rain with the ECMWF suggesting it holds off until Tuesday night. Blended MOS POPs show a small chance of showers moving into western sections Tuesday afternoon, but the highest POPs are reserved for the overnight. Cyclonic flow aloft will then dominate the flow pattern through Thursday. The cool air aloft will help trigger a few mainly diurnal showers Wednesday and Thursday. The showers will tend to favor northern and western higher elevations. Temperatures will be significantly cooler for the second half of the week. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... A few more showers moving across the area as of 5 AM. 09Z TAFS adjusted for this. Earlier discussion below. A band of showers and a few thunderstorms is pushing across the area as of midnight. Some rotation on cell heading toward IPT. Strong southeast flow off the mountain south of IPT for a few more hours. Another area of showers and storms over far southwest PA. Expect this area to slowly work to the northeast and linger into at least into the mid to late morning hours. Skies should try to clear later today, but the cold front will be well to the west. Main concern is the very high dewpoints in place, one of the few times this summer. Main difference this event is that the low level winds shift to the south and southwest, unlike recent events, that seem to occur at the end of the week this season. For now, will use VCSH for the most part. Potential is there for storms with heavy rain and strong winds. Weekend not looking bad for a change. .OUTLOOK... Sat-Mon...No sig wx. Tue...SHRA/TSRA poss. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Martin

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