Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 201222 AFDCTP Area Forecast Discussion National Weather Service State College PA 722 AM EST Fri Jan 20 2017 .SYNOPSIS... A weakening warm front will push across the state today. Relatively mild conditions will persist through the weekend before cooler air makes a return next week. A complex storm system is expected to move off the Mid Atlantic coast Monday and Tuesday and could bring a return of wintry weather. && .NEAR TERM /THROUGH TONIGHT/... A weakening warm front extends from northern KY eastward through southern Va. Milder air is making progress northeastward bringing a shield of rain along with it. Guidance suggests the rain will overspread the region around or shortly after sunrise. The biggest issue with the advance of the rain is whether surface temps rebound enough to prevent a period of freezing rain. Latest HRRR is colder and shows spotty Freezing rain along the leading edge as the rain progresses northeast. Being the hours of the morning commute, we have issued an Advisory for a few hour period of freezing rain to cover the possibility of some light icing. The precip will continue off to the northeast with improving conditions expected for the afternoon as the steady rain turns to just scattered showers. As we have seen so many times this season, the low level cold air will be stubborn to dislodge, so while it will be quite mild over SWRN Pa today, the ridge-valley area of central Pa will stay locked in with temps only in the upper 30s to mid 40s. With just some scattered showers early tonight, the overnight temperatures will stay steady or only fall back slowly as we become ensconced in a mild SW flow between high pressure over the Mid Atlantic and a stronger low moving through the upper Midwest. Lows in the 30s and 40s will be some 15-25 deg above normal for the dead of winter. && .SHORT TERM /SATURDAY/... Saturday will be mild with a fair amount of cloudiness, but mostly rain free. I cannot rule out a stray shower, especially over the NW, but the chances are very low and I chose the more optimistic forecast not mentioning rain. Highs will average in the 40s and 50s, well above normal. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... The upper ridge is forecast to re-establish itself over the eastern U.S. early in the period, as a very complex storm system gathers over the southern Rockies by Saturday evening. This southern stream low is tracked through the southern states before turning northeast over the eastern US early next week. Meanwhile the models build high pressure over eastern Canada and gradually ooze colder air south into the NERN US. By late Monday into Tuesday morning, the parent upper low is made to track into the Mid Atlantic states. The deterministic GFS has the southernmost track, through eastern NC then up just off the coast. The GEFS has a slightly more northern track through VA. The ECMWF and its ensemble partner are more north taking the storm up through eastern PA. The ECMWF tracks its sub 990mb surface low through the Del Marva up along the NJ coast is what we look for as a "sweet spot" for snowstorms locally. Temperatures are marginally cold so it`s still questionable what the precip type will be. But it`s the most interesting pattern we have seen this winter for the snow-birds among us. After our early week storm system, the eastern ridge is made to make a rapid rebound, even if for just a short time around midweek. A fast moving shortwave quickly chews the top off the ridge we are made to evolve into a cyclonic westerly flow by week`s end. It will turn cooler, but not especially so as there really is no truly cold air over North America at the current time. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... 12Z TAFS sent. Area of rain to the west. The concern for the next few hours will be for the potential for freezing rain until around 10 AM. Otherwise, the main thing will be a wide range of conditions today, as things get better for a few hours here, before the rain moves in. Some clearing tonight, but there will still be some potential for a shower or two, low clouds, fog. Most of Saturday and early Sunday looks ok at this point, but some rain possible again later Sunday, mainly across the south. Looks like Monday and Tuesday will be wet days. Outlook... Sat...Low CIGs likely, mainly in the morning. Sun...IFR/MVFR CIGs likely. Rain advances fm S-N. Mon...Rain/low CIGs likely with snow possible central Mtns. Tue...AM rain/snow and low CIGs possible. && .CTP WATCHES/WARNINGS/ADVISORIES... Freezing Rain Advisory until 10 AM EST this morning for PAZ017>019-024>028-033>036-056-063>065. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Martin

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