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Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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725 FXUS61 KCTP 181933 AFDCTP Area Forecast Discussion National Weather Service State College PA 333 PM EDT Thu Jul 18 2024 .SYNOPSIS... High pressure will bring mainly fair weather with seasonable temperatures through the end of the week. Humidity increases a bit this weekend with some areas seeing a scattered shower or thunderstorm on Saturday, but most areas will remain dry. The next best chance for rainfall will come late Monday and Tuesday of next week as a slow moving frontal system lifts across the region. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Comfortably lower dewpoints are pushing into the Lower Susq River Valley this afternoon, with upper 50s soon replacing mid to upper 60s dewpoints that are still over southern and eastern parts of York and Lancaster Counties. A bit of high cloudiness could linger into this evening over the eastern counties, but mainly clear skies eventually win out later tonight with the passage of the upper trough. Surface ridging and an associated low PW air mass should result in the coolest night we have seen a quite a while. The weakest gradient and most efficient radiational cooling is anticipated over the NW Mtns, where we have slightly undercut NBM min temp guidance. Air/water temp differences of >25 degrees should result in patchy late night fog in the deep river/stream valleys of the Alleghenies. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... Another day of tolerable warmth and generally comfortable humidity levels is in store on Friday, thanks to high pressure over the region. An approaching warm front is likely to spread increasing clouds/humidity into at least Southern PA Friday night, but the odds of any rain look slim, at least until Saturday when isolated to scattered coverage of shra/tsra develops over parts of the Laurels, SC Mountains and Central Mountains. Temps start to creep up on Saturday, along with dewpoints, but will be even more pronounced on Sunday as high temps across the south approach 90 once again Sunday afternoon. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... With the large-scale, upper-level pattern next week, it appears that amplified ridge axes will stay in place across the Intermountain West, as well as from the Southwestern Atlantic into the Southeastern CONUS. In between these two ridge axes, a mean upper-level trough axis will extend from Eastern Canada into the Midwest and the Ohio Valley. In general, the above described pattern will keep excessive heat suppressed to the south and southwest of the Commonwealth. However, southwesterly flow aloft will bring increasingly humid conditions locally. Also, the proximity of the aforementioned upper trough, as well as several surface fronts, will bring the likelihood of diurnally driven (mainly during the afternoon and evening hours) showers and thunderstorms, especially in the Tuesday-Thursday time frame. The silver lining here is that additional beneficial rains could be in the offing for drought stricken sections of PA. For the most part, we can expect daytime highs in the 80s and overnight lows in the 60s, which is rather seasonable for mid to late July. Some of our northern mountainous areas may see afternoon highs stay in the upper 70s, while normally hotter sections of the Lower Susquehanna Valley could sneak into the lower 90s. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... 18z update... There is high confidence (80-90%) of VFR/unrestricted conditions across Central PA through the day on Friday. There are two small flies in the ointment. First, patchy MVFR ceiling bases are out there early this afternoon in the Alleghenies. Thus, we did add a short window for this possibility at KJST through 19-20z. Second, at least patchy fog is likely late tonight into early Friday across Northwest PA. As a result of this, we added a small window at KBFD for fuel alternate-IFR visibilities. NW surface winds 5-10 kt this afternoon, should become light/nearly calm overnight and Friday. Outlook... Sat through Mon... Primarily VFR/unrestricted conditions. Patchy late night/early morning fog and low ceilings are possible. Tue... More widespread afternoon and evening showers and thunderstorms could lead to at least brief restrictions. && .CLIMATE... The max temperature hit 100 degrees at Harrisburg Tuesday, 7/16/24. The last time KMDT hit 100 was back on July 19, 2020. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Bowen NEAR TERM...DeVoir/Fitzgerald SHORT TERM...DeVoir/Fitzgerald LONG TERM...Jurewicz AVIATION...Jurewicz CLIMATE...Steinbugl