Area Forecast Discussion
Issued by NWS State College, PA

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153 FXUS61 KCTP 240032 AFDCTP Area Forecast Discussion National Weather Service State College PA 732 PM EST Tue Jan 23 2018 .SYNOPSIS... Colder air is pouring into the region. A short period of near normal temperatures and scattered snow showers will occur over the Alleghenies tonight into Thursday. The colder temperatures will continue through midweek before another mild period develops for the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Sfc front has cleared all the eastern seaboard. 850 temps are below zero directly ahead, while surface temperatures are only 40F currently, but a well mixed 40F as west winds are gusting over 30 mph at times. Light mixed rain and snow showers are traversing the West Central Mountains but drying up as they pass east of the Allegheny Crest. As mentioned earlier, showers look to be scattered through the night with the most expected to be north of I-80 for the fist half of the night, then more so over the Laurels during the latter half of the night. The upslope will help an inch or two build up on the west-facing slopes of the Laurels and in Warren Co by morning. The SHSN will still be going in the morning, so some slippery travel is possible around drive time.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Brisk and colder weather will last through midweek with snow showers continuing over parts of the western Alleghenies. Any additional accumulation on Wed will be on the highest elevs of the Laurels and Nrn Warren & McKean Cos. The rest of the area will see a couple of breaks and a rather normal post-frontal winter pattern to the strato-cu. The wind will not be as gusty as this evening/early tonight, but there will be gusts into the 17-22kt range. Cold advection still going and not much mixing will keep temps in the m20s N and l40s in the far SE valley cities. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... A reinforcing shortwave may enhance snow showers Wednesday night over the Laurels but overall additional accumulations should be less than 1 inch through 12Z Thursday - confined mainly to the western/northern mountains. Dry weather is expected on Thursday and Friday as high pressure slides over PA. Daytime/high temps will reach a weekly bottom during this period, averaging a few to several degrees below normal for late January, with Fri morning being the chilliest of the week in most places. Uncertainty surrounding the timing and amplitude of the upper trough moving from the Rockies through the Central and Eastern U.S. by late this coming weekend beginning to lessen. Followed WPC preference favoring blends toward a slower, non-GFS solution. This would result in a stronger wave of low pressure to develop over the Appalachians and bring the potential for significant rain (likely) or mixed precipitation (chance) Sunday transitioning to and ending as more of a mix of precipitation by Monday (with QPF potential of 0.75 to 1.50 inches). Though majority of the QPF looks to fall as rain before the colder air sweeps in bringing a return to seasonal temperatures and scattered snow showers. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... The cold front has moved off the coast and we are in the cold gusty westerly flow behind it. Gusty winds will continue into Wednesday with scattered snow showers mainly over the usual higher elevations of the west and north where MVFR ceilings will be common, and with visibilities occasionally sub VFR in the passing snow showers. High pressure will move in later Wednesday with most terminals becoming or remaining VFR. Outlook... Wed...AM shsn possible w mtns. Thu-Sat AM...No sig wx expected. Sat PM-Sun...MVFR poss in SHRA. && .HYDROLOGY... Harper Tavern is above flood now, and could take much of the evening to fall below FS. Hershey is also nearing flood stage, but the Hershey stage started out relatively lower than Harper did. It will be close, and will continue to watch it very closely. Flood watch remains in effect for another two days due to lingering concerns surrounding minor flood/ice jam potential along and near the Susquehanna River between York Haven and Safe Harbor. Much drier weather over the next 4 days and a gradual warm up back to well above normal later this week should greatly reduce the threat for ice jam flooding. && .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch through Thursday afternoon for PAZ065-066. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...Dangelo LONG TERM...RXR/Steinbugl AVIATION...Dangelo/La Corte HYDROLOGY...

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