Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 220854 AFDCTP Area Forecast Discussion National Weather Service State College PA 454 AM EDT Sun Apr 22 2018 .SYNOPSIS... High pressure will keep us fair through Monday. Developing low pressure will lift northeast along the eastern seaboard during the middle of the week. Behind this system, an upper level trough will set up over the northeast conus. && .NEAR TERM /THROUGH TONIGHT/... Broken to overcast mid/high clouds are streaming ESE across southern PA as moisture spinning around the emerging upper low over southern Nebraska gets caught up in the upper deformation zone. Previous shift pondered a Frost Advisory, but decided against given the proximity of the clouds. Deformation cloudiness will affect the far southern zones, otherwise it will be another fine day with temperatures managing to top 60 over most of the area...for a change. The overnight will be clear to partly cloudy with temperatures generally dropping back into the 30s. && .SHORT TERM /MONDAY/... Monday will be the last of the dry days in this recent string. Highs will be in the mid to upper 60s with a SE wind being the harbinger of the clouds and rain that will follow. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The slow moving upper low over Nebraska is slated to continue crawling eastward under the Rex Block with the first showers expected to reach SW PA by Tuesday morning. The low is forecast to open up and track NE through the region Tuesday-Wednesday accompanied by periods of rain...no snow! Several other shortwaves are stacked up in the flow well to our west and they will eventually conspire to carve out a new long wave trough over the eastern US by the end of the week and weekend. In the meantime there are differences in the timing details as we move into Thursday and Friday. The GFS/GEFS are faster with the upstream wave dropping out of the upper Gr Lakes, suggesting rain makes a rapid return by Friday. The EC is again slower on Friday, suggesting a dry and mild day. With such low confidence, I leaned toward the model blended guidances which give chance POPs. The differences continue into the weekend with the EC making the eastern trough less intense than the GFS/GEFS. The deeper/colder GFS/GEFS would lead to a chance of snow showers over the western and northern mountains Saturday and Saturday night. Too early to bite on that as yet. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/...
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No large changes for the 09Z TAF package. Earlier discussion below. Looking at some mid and high clouds today into late Monday afternoon. 06Z TAFS adjusted some. Earlier discussion below. VFR conds to prevail into Monday with a thin veil of cirrus slowly sagging further southward as high pressure builds into the area. No impediments to flight ops are foreseen in the near term. A slow-moving storm system will affect the area midweek. Cig restrictions may slide northward into JST late Monday night, with expanding ceiling restrictions over the west Tue - and areawide Tue night into Wed night in rain. Outlook... Mon...No sig wx expected. Tue...Rain/low cigs becoming likely PM from S-N. Wed-Thu...Rain/low cigs.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Martin

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