Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 191836 AFDCTP Area Forecast Discussion National Weather Service State College PA 236 PM EDT Wed Oct 19 2016 .SYNOPSIS... A weak cold front will move through and stall just south of the region today. Unsettled conditions will redevelop for the end of the week as a series of low pressure areas ripple up along an approaching cold cold front. Brisk and much colder weather will move in for the weekend. && .NEAR TERM /THROUGH TONIGHT/... The meso anal suggests what`s left of the slow moving front is pretty much stalled in the vicinity of the Mason-Dixon line. The most enhanced clouds pretty much depict this feature from SW Pa to the lower Susq Valley. Temps are rising quicker than earlier expectations pretty much assuring more records will fall in the unusually warm and even a bit humid airmass. Latest update tweaked afternoon max`s up several degrees across the board. It will continue mild overnight as the low level flow quickly turns southerly ahead of the wave that will be approaching from the midwest. Increasing warm advection will help bring about an increasing chance for rain the deeper into the overnight we get, with the best chances for rain by morning being over my western and northern zones. && .SHORT TERM /THURSDAY/... The first in a series of surface waves will enter Pa by Thursday afternoon. The surface pattern will be rather complex by that time with a low and cold front moving into the western part of the state, and a warm front extending east before dog-legging down through the Central Mountains and east to the coastal plain. The forecast surface based LI`s depict this cool air damming scenario lasting at least through mid afternoon before we mix out and see the warm front become established to the NE of the region. This also complicates the rain forecast with the best chance of rain for the first half of the day looking to be over NWRN Pa associated with the increasing frontogenetic forcing under the strengthening right upper jet entrance region. To the east we should see a more misty/showery rain overrunning the wedge of cooler air over most of central and eastern Pa. As we see the warm air progress north we could actually end up with another very warm and rain free afternoon over much of the central and eastern part of the forecast area as the rain concentrates closer to the low and cold front over western areas. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Low pressure developing northeast of the Turks and Caicos (currently being monitored by NHC) is forecast to track northwest and then north ahead of the deep layer trough approaching the East Coast by the end of the week. The models show some differences concerning the possible interaction between this low and the aforementioned surface low with the CMC the most bullish. The full range of guidance suggests odds are slightly higher for the two system to remain largely separated with eventual consolidation and further deepening likely by the time the system reaches northern New England by early Saturday. This will result in a colder and brisk/gusty northwest flow pattern with some potential for wrap- around/deformation precipitation giving way to showery regime focused downwind of Lake Erie and over the higher terrain of the Alleghenies/Laurel Highlands. Surface-850mb temps will be marginally cold enough to support rain/snow showers Saturday (and especially Saturday night)over the NW mtns and Laurel Highlands with a low probability for a light coating Sat night at Elevations above 2200 ft MSL where some heavier bands of Lake Effect or Orographic showers occur. Some snow pellets are even possible just SE of the Allegheny Front in any brief heavier showers late Saturday afternoon and night as 850 mb temps dip to -2 to -3C. Also...ramped up wind (and wind gusts to a conservative 25-30 kts for now)- during the Saturday afternoon and evening period. Bufkit profiles indicate a deep boundary layer with the well mixed layer tapping some 35 to 40 kt wind at just 3-4 kft agl. GFS/EC show a fast- moving low diving through the Great Lakes into early next week. This system has low predictability given it weak state embedded within a progressive WNW flow aloft. Temperatures start off very mild for the later half of October but trend noticeably colder/below normal by the weekend. The roller-coaster up and down swing in temperatures is not uncommon for this time of year and will only continue as the calendar turns towards winter. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Widespread VFR will continue into the overnight. A developing storm/frontal system over the Ohio Valley will spread low clouds back into the western mountains overnight on nose of increasing southerly low-level flow. A larger-scale rain event will impact the area Thursday into Friday night, bringing widespread reductions (with IFR likely north and west). Outlook... Thu-Fri...Widespread reductions (with IFR likely N/W). Scattered showers SE, periods of rain elsewhere. Sat...Restrictions NW. Sct showers NW. Brisk NW wind. Sun...No sig wx. Mon...Mainly VFR. MVFR with rain showers possible NW. && .CLIMATE... New daily record maximum temperatures were set yesterday 10/18 at Harrisburg (84) and Williamsport (84) with a tie at Bradford (75). Here are the current records for 10/19: Harrisburg: 82 in 1945 Williamsport: 82 in 1963 && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...Lambert/Steinbugl AVIATION...La Corte CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.