Area Forecast Discussion
National Weather Service State College PA
416 AM EDT Tue Aug 12 2025
.SYNOPSIS...
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* Humid with locally heavy thunderstorm downpours tonight and Wednesday * Mainly dry with above normal temperatures all weekend
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Patches of lower clouds have started to form over the Lower Susq and Laurels. While not a widespread deck yet, it is expanding. Much of the area could have these clouds (which are currently 1500-2000ft aloft). That could make it more difficult for us to reach the NBM mean MaxTs. But, mixing should help break these clouds up for the most part. Without much confidence in the persistence of the clouds, we`ll hang close to guidance for the time being. Many of the CAMs pop taller cu and even isolated showers this afternoon, mainly S of UNV. They`ll get tallest over the ridges/high ground and only drift away slightly. Coverage of any showers is expected to be pretty sparse, and only worthy of a 20-30 PoP.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
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All of the pop-up showers around this afternoon will die off around sunset. The advancing upper trough will really break down the ridge and drag a cold front into OH overnight. There will be some showers and possibly a thunderstorm get into the western zones before sunrise Wed. Lows tonight will be milder, especially in the Lower Susq where they should stay in the 70s. Pre-frontal weaknesses in the pressure field will allow storms to continue going during the morning hours as the front nears the CWA. The afternoon heating will increase the coverage of the storms with skinny but tall CAPE NW, and fatter CAPE as you move SE. 0-6km shear will be around 30kt for BFD, but only 20kt at UNV and MDT. These numbers aren`t enough to cause concerns high enough to the SPC outlooks, but a strong-er storm is possible. The high PWAT (1.7-2.0") and slow moving storms may make heavy downpours. That shouldn`t be much of a concern, either due to the very dry conditions of the past week plus. It`s been about two weeks since Happy Valley has had measurable rainfall. Lancaster and Bedford counties had very heavy rain ~10-12 days ago, but not much (if anything) since then. The front seems like it moves only slowly when it gets into Central PA, and should yield more showers and storms. Expect these to drag in the southern zones until the middle of Wed night. The dry air does make inroads across the north.
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