Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 131049 AFDCTP Area Forecast Discussion National Weather Service State College PA 649 AM EDT Thu May 13 2021 .SYNOPSIS...
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High pressure centered over the midwest will drift east across Pennsylvania by this weekend. The high will pass off the east coast early next week, with a warm front potentially lifting into the state by the middle of next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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After a chilly and sunny start to the day, expect a fair amount of diurnal cumulus in response to upper trough over the region. Much as occurred yesterday, expect just enough instability to support isolated, light showers/sprinkles during the afternoon over the elevated terrain of the Alleghenies. Have undercut NBM temps slightly today based on an expectation of a fair amount of afternoon cumulus and 850 temps of 4-5C, which supports highs ranging from around 60F over the Allegheny Plateau and the upper 60s across the Lower Susq Valley.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
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Surface high will slowly build into the region tonight, supplying another night of fair and chilly conditions. However, the Canadian air mass associated with this feature should continue to modify, resulting in low temperatures several degrees above those of this morning. Still, patchy frost will likely be a concern over the northwest mountains. Pennsylvania will remain under the influence of a mean upper level trough Friday, resulting in the chance of isolated PM showers. It looks like there will be a better chance of showers Saturday afternoon, when models track a shortwave directly over the state during max heating of the afternoon. The cool weather of the last several days should transition to near average temperatures by this weekend, as the Canadian high pressure system continues to moderate and slide east over Pa.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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On the large scale, the blocky pattern that we`ve had in the northern stream, featuring a persistent closed upper high over south-central Canada and a trough axis/lower heights extending from eastern Canada into the northeastern CONUS, should gradually open up and become more progressive. The main impact of this transition will be warmer, more seasonable temperatures over time for central PA. The combination of cool temperatures aloft and still residual short-wave energy from the aforementioned trough axis as it lifts out/weakens will produce isolated and diurnally enhanced convection once again on Sunday. However, limited overall coverage means the majority of us will stay dry. Fairly weak flow over a deep layer of the atmosphere may also anchor any isolated convection that forms mostly to terrain features. Early next week, as a low-level warm front slowly approaches from the southwest and more moisture gets injected into the atmosphere locally, we should see at least somewhat increased coverage for shower activity. As alluded to earlier, temperatures will be moderating back towards seasonal normals for central PA, with daily highs ranging from the upper 60s-mid 70s and nighttime lows in the 40s-lower 50s.
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&& .AVIATION /12Z THURSDAY THROUGH MONDAY/... High pressure will very slowly build in from the west through the next few days bringing mostly dry conditions. Light wind this morning, followed by some diurnal cu and an increase in wind from the N for the aftn. A sprinkle or two is expected over the Alleghenies as a short wave trough passes overhead again. Fri aftn may hold a few more SHRA, but most/all of the time should be VFR. Any flight category reductions will likely hold off until Sat aftn when diurnal convection looks like it will be more organized and dewpoints/moisture higher. Outlook... Fri-Sun...VFR. A few SHRA possible each aftn, mainly over the central mtns. Mon...VFR. SHRA poss, mainly S. && .CLIMATE... The record low temperature for Thursday morning (5/13) in State College is 31 degrees. The mercury will likely fall several degrees shy of that value. && .CTP WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 8 AM EDT this morning for PAZ004>006- 010>012-017>019-024-025-033-034-037-041-042-045. && $$ SYNOPSIS...Fitzgerald NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Jurewicz/Colbert AVIATION...RXR/Colbert CLIMATE...

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