Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 180901 AFDCTP Area Forecast Discussion National Weather Service State College PA 501 AM EDT Mon Mar 18 2024 .SYNOPSIS...
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An upper level trough will swing across Pennsylvania today, followed by a reinforcing shortwave and associated cold front on Wednesday. High pressure is likely to build over the area Thursday. A dying cold front is likely to approach from the Great Lakes late next week, as a southern stream shortwave passes well south of the state.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SCT SHSN rolling across the area, but the only ones bringing the visibility low enough and places with temperatures low enough to generate any accumulations are just N of I-80 and dropping into Lock Haven and Williamsport at 4 AM EDT. There is very little organization to the SHSN and they are moving quickly. Expect only a dusting this morning. There aren`t many breaks in the cloud shield back over nrn OH and lower MI. Daytime may mix things up a little better, and lead to some breaks. The long wave trough swinging overhead today will continue to generate a broad area of lift and potentially lead to steep lapse rates/instability. The latest snow squall parameter values from the HRRR and NAM maximize in the evening as a good sfc trough moves across the lower lakes and into the NW mtns/Alleghenies. Frontogenesis is weak through the period, and at that time, we would also be losing the help of the heating to lower the stability. Plenty of snow showers, and it will be gusty, too, but it`s not the best set-up. Flash freeze possibilities look generally poor. The NW is the only worry spot for squalls. General accumulations will be less than an inch NW and less than an inch for the central mtns. SCT SHSN do last into the night over the Laurels, but accums there will be very minor. Even if some flurries fly in the SE, the temps should be mild enough (m40s) to melt anything that tries to stick.
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&& .SHORT TERM /10 PM THIS EVENING THROUGH TUESDAY NIGHT/...
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After the troughs overhead and at the sfc pass, the subsidence should quell the SHSN/SQ for at least the next 18 hrs into late Tuesday. The ridging should also push lake effect snows to our N. A northern stream wave/Clipper moves across ONT into NY late on Tuesday and does not bring the coldest of the air across PA until Wed. The warm advection does nudge into PA. The associated cold front will not arrive until the overnight. That will likely touch off SCT SHSN, but squalls should not be very likely without much instability. Mins tonight will be below freezing for all. Temps on Tuesday will be very similar to today/Monday. The warm advection and more clouds Tuesday night will keep the mins up just a little vs tonight - in the u20s to m30s.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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The passage of the trailing cold front Wednesday should be accompanied by scattered snow showers, a few of which could survive into the Susq Valley due to strong forcing ahead of the upper level shortwave. Steep lower tropospheric lapse rates indicate the potential of some heavier snow squalls, mainly across the N Mtns. Fair, but still cool, weather appears likely Thursday, as the trough lifts out and surface ridging builds in from the Grt Lks. Medium range guidance suggests a few rain showers are possible Friday, mainly over the N Mtns, associated with the approach of a dying cold front. The bulk of guidance tracks a more significant southern stream shortwave and associated area of low pressure well south of PA next weekend. Therefore, fair and seasonal conditions currently appear likely next Sat/Sun.
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/... Mainly high clouds are present in the airspace this evening with a few spots that contain broken MVFR cigs, mainly in the western mountains. Isolated lake effect snow showers are possible in the NW, everywhere else should expect dry, cold, and some breezy conditions. Borderline VFR/MVFR cigs could spill into the central mtns (AOO, UNV, IPT) during the late evening hours as cooling aloft occurs with the approach of a few upper level disturbances. The Lower Susq Valley (MDT, LNS) should remain VFR right through tonight and Monday. West-northwesterly wind will frequently gust between 20 and 25 MPH this evening, before subsiding by 5-10 mph overnight then picking back up to similar speeds and gusts around mid morning as mixing occurs in the lowest levels of the atmosphere. Outlook... Monday-Friday...Periodic snow showers and reductions, primarily across the higher terrain of northern and western PA. This will be enhanced by reinforcing shots of unseasonably cold air and gusty W/NW winds. West to northwest wind gusts could peak in the 35 to 40 mph range on Wednesday. && .CLIMATE... Astronomical Spring (vernal equinox) begins on Tuesday March 19 at 11:06 PM EDT. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald/Dangelo NEAR TERM...Fitzgerald/Dangelo SHORT TERM...Fitzgerald/Dangelo LONG TERM...Fitzgerald AVIATION...Bowen CLIMATE...Steinbugl

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