Area Forecast Discussion
Issued by NWS State College, PA

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802 FXUS61 KCTP 190554 AFDCTP Area Forecast Discussion National Weather Service State College PA 154 AM EDT Thu Oct 19 2017 .SYNOPSIS... For the most part our weather will be dominated by a surface high and an upper-level ridge through late Sunday. A weak short-wave comes over the ridge on Thursday without significant moisture. Our first real chance of rain will be early next week when a trough moves our way. By mid-week we could see some below normal temperatures with a deep trough just to our west. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... Another cool and tranquil night is underway with high pressure over the area resulting in efficient radiational cooling. Based on 05Z dewpoint depressions, as well as NAM/SREF output, patchy valley fog appears a good bet early this morning across the eastern half of the state. Temps on track to bottom out from the upper 30s in the coolest valleys, to the mid 40s on the hilltops and urban areas of the Lower Susq Valley. && .SHORT TERM /7 AM THIS MORNING THROUGH FRIDAY NIGHT/... Warm air, with maximum temperatures 5 to 10 degrees above normal, will continue through Friday. A shortwave tracking well north of Pa will push a dying cold front into our region late today. Models indicate just enough moisture preceding this front to produce sct late day cu across the northwest mountains. Otherwise, it will be another sunny day. Expect a bit more wind today with the weak frontal surge. Rain chances through Friday are near zero. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A strong upper level ridge of high pressure will support above average temperatures through the weekend. This will further add to the anomalous October warmth which should help to secure a spot in the top-10 warmest Octobers - if not top 5 or even #1. Both GFS and ECMWF ensemble systems continue to indicate a pattern flip by the middle of next week with a period of colder (near/below normal) temperatures starting around October 25th. The depth and longevity of the emerging upper trough and subsequent cooler pattern remains in question - so we will have to wait and see how much of a dent it can put in the strongly positive month-to-date departures from climatology. On the precipitation side, the prolonged dry spell ends early next week as a cold front moves across the Appalachians. Stream separation differences/closed low development in some of the deterministic models leads to increasing spread and thus uncertainty in the forecast details such as timing. The GOM will be open for moisture inflow northward ahead of the front. So will keep continuity and favor max POPs in the Monday night- early Tuesday timeframe. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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GOES-16 fog channel is starting to show valley fog formation across portions of the central and eastern airspace. Surface obs indicate eastern TAF sites have decoupled with temp/dewpt spreads tightening to within a few degrees. Therefore expect greatest odds for restrictions at KIPT, KLNS and KMDT in that order. Fog should dissipate by 14z giving way to VFR. To the west in ZOB sector, expect VFR to prevail through the period. Wind gusts will reach the 15-20kt range over the western 1/2 of the airspace from late this morning through the afternoon. A dry cold front will push across the airspace this evening and early tonight accompanied by a light wind shift from 220-250 to 270-330 degrees. High pressure moves back over PA late tonight into Friday morning. Outlook... Fri-Sun...Patchy AM valley fog otherwise VFR. Mon...VFR to MVFR. Showers possible into Monday night. LLWS likely Monday night into early Tuesday.
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&& .CLIMATE... Month-to-date, October 2017 is the warmest October on record at Harrisburg and Williamsport. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Grumm NEAR TERM...Fitzgerald SHORT TERM...Grumm/Fitzgerald LONG TERM...Ceru/Steinbugl AVIATION...Steinbugl CLIMATE...Steinbugl

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