Area Forecast Discussion
Issued by NWS State College, PA

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703 FXUS61 KCTP 020311 AFDCTP Area Forecast Discussion National Weather Service State College PA 1011 PM EST Thu Dec 1 2016 .SYNOPSIS... A large and deep storm system will move slowly through Quebec over the next couple of days keeping a prolonged period of cool northwest flow over the local area. High pressure will build in for a brief time Sunday before the next frontal system approached early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... No big changes late this evening as lake effect regime continues tonight. Lake clouds and flurries hugging areas along and north of the PA/NY border this evening are showing a slight southward drift. Latest HRRR in good agreement with this trend for the backing flow upstream flow evidence in northeast Ohio should bring this to fruition. Expect an increase in snow shower activity after midnight across the north. Boundary layer and sfc marginally cold and bands not expected to become very organized. However...a light accumulation will be seen over my northern tier overnight. Some sprinkles still mixed in in areas where lighter precip rates occur. Mins will be fairly uniform throughout...ranging from the lower 30s northwest to the lower to middle 30s elsewhere. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... The cold NW flow will remain air in place for Friday, but again the cold air is unimpressive so NW snow shower activity is not expected to amount to more than nuisance amounts. With high temps expected to be above freezing, most areas will ave a hard time making any snow stick at all. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... As low continues to move further east into the Canadian Maritimes, lake effect snow showers over the NW mtns will gradually wind down on Sat. But one last shortwave Fri night could be enough to extend snow bands into parts of the central mtns for a time. Sunday brings a brief respite as high pressure moves over the state. By late Sunday into the overnight, a period of light snow is possible as a northern stream shortwave races through the region with a burst of warm advection. QPF looks to be on the order of a tenth of an inch or less, but occurring overnight many places could see their first coating of snow of the young season by Mon morning. Another ridge moves through on Monday as progressive weather pattern becomes more active. On Tues there is decent agreement in bringing the SW US upper low up through the OHIO Valley as a shearing out shortwave and diffuse surface low. Unless cold air damming traps enough chilly air in the low levels to make for some freezing rain, the precip type with this midwest system looks to be mainly rain. The end of the week brings some model disagreement with the GFS/GEFS being faster than the ECMWF with the next large upper trof and frontal system. Either way, precip looks like a good bet around the Thu/fri period as all solutions eventually bring this trough through. So predictability is increasing, but timing issues remain. Best bet for precip at this point is mainly rain over the SE as decent push of warm air lifts ahead of the system, with a rain/snow mix further north where warm air will not infiltrate as much. Behind the trough, looks like a chilly weekend in store with a potential sharp dropoff in temps. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Widespread MVFR to low end VFR CIGs will persist through the overnight over the favorable cold advection/upslope region from KBFD to KJST (and possibly extending briefly at times into the KUNV/KAOO areas), with VFR, BKN-OVC conds across the east scattering out late across the Lower Susquehanna Valley airfields - KMDT, KLNS, KMUI and KTHV. An initial mean WSW wind flow in the boundary layer will keep lake effect snow showers mainly north of the PA/NY border through 05Z Friday. Last several runs of the HRRR and BUFKIT time/height cross-section continues to show a slight (10-15 degrees) veering to the mean wind within the sfc-850 mb layer (to about 280-285 deg) which will cause the bands of enhanced lake effect snow showers to shift slowly south from the Western Southern Tier counties of NY, into NW Pa at times late tonight and Friday. Thus, IFR vis reductions appear likely, and will become more persistent at KBFD very late tonight into Friday. Outlook... Fri-Sat...MVFR CIGS and ocnl SHSN accompanied by IFR vsbys at KBFD/KJST. Mainly MVFR to low-end VFR cigs and VFR vsbys at KAOO, KUNV and KIPT. Sct-Bkn VFR Cigs and VFR vsbys expected to continue at KMDT and KLNS. Sun...Slight chance of light snow/reduced vis at night. Mon...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Gartner NEAR TERM...DeVoir/Gartner SHORT TERM...La Corte/Gartner LONG TERM...La Corte/RXR AVIATION...Lambert/Gartner is the U.S. government's official web portal to all federal, state and local government web resources and services.