Area Forecast Discussion
Issued by NWS State College, PA

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064 FXUS61 KCTP 251454 AFDCTP Area Forecast Discussion National Weather Service State College PA 1054 AM EDT Mon Sep 25 2017 .SYNOPSIS... Unseasonable late-September heat will continue in central PA through mid week. Mostly dry weather will also prevail with just an isolated shower possible in spots on Wednesday. A pattern change will bring cooler, fall-like weather back to the area for end of the week and into the upcoming weekend. && .NEAR TERM /THROUGH TONIGHT/...
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GOES-16 visible satellite shows valley fog has dissipated this morning, giving way to abundant sunshine. Expect another unseasonably warm and muggy late- September day with max temperatures in the mid 80s to around 90F (+15-20 degrees above normal). It will feel even warmer with max HX values between 90 and 95 degrees. Hard to deviate from persistence in this pattern. Tonight will be another repeat: very mild with mainly clear skies and more valley fog after midnight.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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Another day of summerlike heat and humidity expected across central PA. Highs may be trimmed a bit across southeast PA as some clouds bands associated with Maria wrap into the area. Some hires and even coarser global models try to develop some isolated convection Tuesday afternoon but odds remain strongly in favor of dry wx pattern.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/... The blocking high that has been responsible for the recent extended spell of dry and anomalously warm conditions is forecast to start breaking down by mid week, with shortwave energy sliding along the US-Canadian border finally chewing away at the high heights and bringing some cooler air eastward. In the meantime Maria is still forecast to drift northward into the offshore waters off of Cape Hatteras on Wednesday. But the aforementioned northern stream shortwave finally gives it the incentive to take a hard turn east as the storm passes 35 deg north. For our area, it looks like the first chance we will have to see any rain might be later Wednesday with a weakening cold front that is destined to fall apart in the unfavorable shear on the northwest side of the sprawling hurricane. Any rainfall looks to be scattered and light, bringing little change to the dry conditions we`ve had around here for much of September. A bit more significant trough will approach for the end of the week into the weekend. The ECMWF has backed off and now looks much like the GFS with a flatter faster wave, and a return to ridging by Sunday. The atmosphere will be dry so there doesn`t seem to be much of a chance for significant rain, just scattered light showers. We will likely go on into at least 3 weeks without any widespread beneficial rain. The biggest change will be that temps will drop off from our streak of well above-normal levels back toward seasonal normals by Friday. && .AVIATION /15Z MONDAY THROUGH FRIDAY/...
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Valley fog once again dissipating to widespread VFR conditions. No reason to deviate from persistence with fog restrictions likely again early Tuesday morning. Tue...AM valley fog becoming VFR. Wed...Spotty PM shower possible. Mainly VFR. Thu...No sig wx expected. Fri...Isold-sct showers possible. Mainly VFR.
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&& .CLIMATE...
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Record-challenging late-September heat through early week. Daily high temperature records for 9/25 and 9/26: Bradford: 83 in 2007, 79 in 1998 *Williamsport: 89 in 1970, 92 in 1900 Harrisburg: 93 in 1970, 91 in 1970 Altoona: 90 in 1970, 88 in 1998 *Williamsport maximum temperature records are under review for Saturday and Sunday 9/23-9/24.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...La Corte AVIATION...Steinbugl CLIMATE...Steinbugl

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