Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 231958 AFDCTP Area Forecast Discussion National Weather Service State College PA 358 PM EDT Sat Jun 23 2018 .SYNOPSIS... A warm front will move into the region this afternoon and a cold weak cold front will pass through this evening. A secondary cold front will settle south through the area Sunday. Sunshine and lower humidity will return Monday and Tuesday. A new frontal system will bring more showers ahead of hot and humid weather that will become established late next week into early July. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Prospects for severe storms are very dependent cloud cover, and seem to be dwindling as thus far the clouds over the Slight Risk area continue to stubbornly hold on. As of 18Z the warm front remains between JST and AOO with breaks in the clouds most evident over the Laurels up into the NW Mountains. This is where the RAP has the most CAPE, which is not very much. Mixed layer CAPEs are just topping 200J and mid level lapse rates are pretty weak. The Slight Risk area accounts for a small sliver of my SERN zones where low clouds and an easterly wind are hanging tough. The warm front and a true wind shift to the SW look like it has just gone through HGR. Latest RAP still predicts SFC based CAPE of 800-1200J over my MD border counties from about 19-23Z along with deep layer shear in excess of 40kt. If this can still manage to happen, scattered strong storms will be possible, but my confidence at this point is low. SPC maintained a small portion of the lower Susquehanna Valley with a SLIGHT Risk and the MARGINAL Risk north/west to cover the remainder of south-central PA. Damaging wind will be the main threat. Coverage of showers will diminish later this evening with just an isolated shower possible after midnight. Some low clouds in the increasingly humid airmass will be possible, and if any measure of clearing can happen fog will also be possible. The best chance will be over the SE. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... A secondary cold front will push south through the state tomorrow and tomorrow night with more scattered showers and storms. Drier air will follow in its wake. The best chance for rain looks to be over about the northern half of the forecast area. It will be warmer than today and quite muggy as dewpoints are expected to be well up into the 60s in most areas. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... *Dangerous heat conditions possible late next week/weekend A cold front will clear the area Sunday night, with Canadian high pressure directing a less humid/more comfortable air mass into PA early next week. A two-day stretch of pleasant, dry weather with comfortable humidity is expected Monday and Tuesday. Added a few degrees to maxT and shaved Tds a bit based on abnormal dry airmass for late June. Valley fog is a good bet Monday night/AM Tuesday especially across north-central PA with low temps in the mid 40s. Showers and thunderstorms return for midweek followed by building heat and humidity late week. While there are some timing issues which is not unusual at this range, there has been a fairly coherent model signal for the next round of showers/storms to hit the area on Wednesday. The big story during the second half of next week (possibly lasting into early July) will be the hot/humid conditions becoming established across the mid-Atlantic/Northeast states in association with anomalous upper ridge. Max heat index grids for Friday suggest the potential for heat advisory conditions across the Susquehanna Valley. Will highlight the heat risk in the HWO. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... The eastern flying area is north of the warm front and has managed to hold onto fairly widespread IFR and MVFR ceilings. Breaks have developed in the warm airmass over western PA into the Laurels where more numerous showers and thunderstorms have developed in the unstable airmass. Scattered thunderstorms will spread eastward into the central areas and eventually eastern areas through the early evening hours. Storms should exit the eastern airspace by midnight. Lingering showers are possible across the western airspace tonight with weak westerly upslope flow and residual moisture resulting in MVFR to IFR cigs at KBFD/KJST into Sunday. Another round of showers/storms is expected on Sunday. .Outlook... Mon...Low cigs psbl N/W airspace early, then improving. Tue...Patchy valley fog in the morning, otherwise VFR. Wed-Thu...Thunderstorm impacts likely. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...Gartner/Steinbugl AVIATION...La Corte

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