Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190537 AFDCTP Area Forecast Discussion National Weather Service State College PA 137 AM EDT Sat Aug 19 2017 .SYNOPSIS... A cold front will pass east of the area tonight. An upper trough will move across the region Saturday afternoon and evening. Temperatures will stay above normal but rise even higher each day through 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 /UNTIL 6 AM THIS MORNING/... Satellite loop at 01Z still showing a line of cumulus along trailing cold front running from near KIPT south to near KHGR. Will maintain the chance of a shower/storm along and east of this boundary through the late evening hours. Latest radar trends and HRRR support POPs of only around 20 pct across this area through around midnight, then patchy fog will become the issue. Latest SREF and downscaled NAM suggest the weakest gradient and best chance of fog will be across the Susq Valley, but patchy valley fog is also likely further west. A push of drier air behind the cold front, along with light wind and mostly clear skies, should allow temps to fall to near 60F over the northwest counties and to the upper 60s in the southeast part of the forecast area. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... After a mostly sunny Saturday morning, a sharp upper trough will swing eastward from the Ohio Valley, generating afternoon showers and tstorms. Will maintain the highest POPs across the northwest counties, where passage of trough will coincide with time of max heating during early to mid afternoon. SPC continues to highlight the northwest half of the forecast area in a MRGL risk. Model data showing decent mid level winds and deep layer shear, but limiting factor will be only modest instability. Expect convection to diminish in intensity/coverage as it pushes into eastern Pa during the cooling hours of Saturday evening. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... The mid range models are all in good agreement on the timing and strength of the passing shortwave Saturday night. Once that passes, the heights will rise and become quasi-zonal. This will bring fair weather to the region Sunday through Tuesday. Dry westerly flow will also bring warm summertime temperatures with Tuesday continually trending warmer. 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 /06Z SATURDAY THROUGH WEDNESDAY/...
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Patchy fog will be the rule overnight. 06Z TAFS sent. Earlier discussion below. Mainly clear skies over the region this evening. Fog is expected for most of the area tonight, with MVFR to IFR restrictions. Lowest restrictions expected in the southeast, where most significant rain fell this evening. An upper level trough and rather strong forcing passing directly overhead in the cooler air aloft could make scattered SHRA/TSRA across the northern third/half of Pennsylvania on Saturday afternoon. Much drier air will make for a mainly-VFR Sun-Mon with only valley fog in the AM a potential issue. .OUTLOOK... Sat...Mainly VFR, but with sct SHRA/TSRA northern 1/3. Sun-Mon...Mainly VFR, but restrictions in morning fog. Tue-Wed...SHRA/TSRA poss.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo/Fitzgerald NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...La Corte/Ceru AVIATION...Jung/Martin

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