Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 251717 AFDCTP Area Forecast Discussion National Weather Service State College PA 117 PM EDT MON JUL 25 2016 .SYNOPSIS... A cold front will push southeast across Pennsylvania late today and tonight. High pressure will return for mid week with continued warm temperatures. Temperatures may trend back to near or slightly below normal over the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Issued an update to upgrade the Heat Advisory to an Excessive Heat Warning for the sern zones today. A hot and humid airmass is place across the region ahead of a cold front currently extending from southern lower Michigan...SSWD to the Chicago area. Early visuals show mainly scattered clouds so there will be little to inhibit strong solar heating in the already very tropical airmass. RAP analysis shows PWATs in the neighborhood of 2 inches. The southern 2/3 of the CWA is under a Slight Risk today with the primary triggering mechanisms being the cold front a potent mid level trough that will push a well defined upper jet entrance region over southern NY and northern Pa. The NCAR ensemble shows a high probability of CAPEs exceeding 3000J during max heating. Models also develop some impressive helicity as the system enters the region. Lagging upper trough and sfc cold front will combine with the deep tropical moisture to bring the threat of some training storms with highly localized very heavy rainfall of 2 inches or more per hour. Headwater Flash Flood Guidance values are extremely high and 4 inches plus for the 1-3 hour period, so at this point there isn`t a big concern for flash flooding. However, PWATs are just about as high as they get around this part of the country, so the biggest threat will likely be urban and small stream flooding. Ens mean 8h temps support max temps today from the u80s across the Allegheny Plateau, to the m90s across the Susq Valley. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... The relatively weak sfc cold front will slide SE across the SE half of the state late today and tonight, accompanied by scattered showers and perhaps a few tsra early tonight. Clearing skies lower PWAT air, and a rather light WNW breeze of 5 kts or less could lead to some patchy dense stream/river valley fog...esp north late tonight and early Tuesday morning. low temps early Tuesday will vary from the l60s across the north...to the lower 70s across the SE zones. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Big story in the extended fcst is the likelihood for modest cooling by Tue/Wed behind the weak cold front. However, temps still likely to remain somewhat abv normal within a generally zonal flow. Midweek weather looks dry again, with just low pops for isolated tstms. Fri looks to be the next higher chance for tstm impacts areawide as another cool front progged to move through. && .AVIATION /17Z MONDAY THROUGH FRIDAY/...
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Developing thunderstorms are bringing localized restrictions to terminals in the northwest. Thunderstorms will break out in the hot humid air over all of our CWA this afternoon. Some of the thunderstorms could cause damaging wind gusts and large hail, especially over the northern portion of the flying area. Dewpoints will not dip all that much tonight, so areas of fog look like a good bet after the thunderstorms move east of the region. For now will forecast 3-5 miles but would not be surprised to see local IFR conditions develop. The best chance for dense fog will be at terminals that see rain today and clearing skies tonight. Air does get slightly drier for the middle of the week. It should not be cold enough at night to make much if any fog in the valleys of the north. The airfields will likely stay VFR into Thursday. OUTLOOK... TUE-WED...VFR. THU-FRI...Mainly VFR. SCT PM SHRA/TSRA.
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&& .CLIMATE... Record high for Harrisburg today is 99 degrees set in 1940. Record high for Williamsport is 100 set in 1934. && .CTP WATCHES/WARNINGS/ADVISORIES...
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Heat Advisory until 8 PM EDT this evening for PAZ027-028-035- 036-049>053-058. Excessive Heat Warning until 8 PM EDT this evening for PAZ056- 057-059-063>066.
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&& $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Lambert/Gartner AVIATION...La Corte/Head CLIMATE...

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