Area Forecast Discussion
Issued by NWS State College, PA

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432 FXUS61 KCTP 201142 AFDCTP Area Forecast Discussion National Weather Service State College PA 742 AM EDT Sun Aug 20 2017 .SYNOPSIS... High pressure with fair weather will build across the area through Monday. A strong cold front will sweep southeast across the area Tuesday night. Cooler and drier conditions will return for the second half of the new week. && .NEAR TERM /THROUGH TONIGHT/... Satellite images show the valleys overflowing with fog and low clouds as light winds and high pressure build in behind yesterday`s secondary cold front. After the low clouds and fog burn off, high pressure will provide the region with fair weather today. Model soundings indicate just a few cumulus developing during the afternoon. 850 temps near 14C should translate to max temps from the upper 70s across the Allegheny Plateau, to the mid 80s across portions of the Susq Valley. A comfortable night for sleeping is in store tonight as high pressure moves over the state. Some patchy valley fog will be possible once again late at night. && .SHORT TERM /MONDAY/... Dewpoints will begin to creep back up as high pressure slips officer and a low level southerly flow develops. A weak lee- side surface trough is depicted over central and eastern PA in the short term deterministic guidance, and scattered convection is made to develop with afternoon heating about this feature over SERN areas. The SREF and GEFS both show some respectable CAPE developing in the increasingly humid airmass so a stronger storm cannot be ruled out. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The big weather maker looks to be a potent late summer cold front that latest timing shows passing through the region Tuesday night and early Wednesday. After a surge of heat Monday and Tuesday, with some southern locations possibly nudging 90 each day, the strong front will bring a refreshingly cool and dry airmass to the region for the second half of the week. The biggest question will be severe potential with the front. Latest timing shows the front just moving through central Ohio by Tuesday evening. The SREF and GEFS develop very little CAPE near the cold front and into central PA, keeping a finger of unstable air confined mainly to the coastal plain well out ahead of the front. So it remains to be seen if parameters can line up for widespread severe storms with the actual front as at this point it doesn`t seem like the best set up despite the magnitude of the airmass difference and strength of the wind fields. Once again the models are hinting that the coastal plain may be where the action is as the best CAPE and shear are aligned there associated with the lee-side troughing. The remainder of the week into the weekend looks to be cool and mainly dry as a sprawling high moves slowly eastward out of southern Canada. Interesting to note that the deterministic models show 850 temps as cold as 3C just north of the Canadian border behind the cold front, a reminder the change in seasons is not all that far away. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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Fog in and out again as of 7 AM. 12Z TAFS adjusted for this. Fog and any low clouds should be gone by 9 AM. Not many this summer, but expect a dry day with near normal temperatures. Yesterday was not bad, until late afternoon and evening, when widespread storms moved across the area with damaging winds. For tonight, did put a little fog in the southeast late. After sunrise on Monday, the fog should give way to another dry day with decent conditions. Potential for widespread showers and storms later Tuesday, perhaps on the strong to severe side. Strong cold front moves across the region. .OUTLOOK... Mon...Mainly VFR, but restrictions in morning fog. Tue...Thunderstorm impacts likely into the overnight. Wed...Morning SHRA...then becoming VFR Thu...VFR.
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&& .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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