Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 192009 AFDCTP Area Forecast Discussion National Weather Service State College PA 409 PM EDT Thu Oct 19 2017 .SYNOPSIS... High pressure will remain over the eastern conus through the upcoming weekend. Low pressure is likely to track west of the state early next week with a trailing cold front coming through Pennsylvania Tuesday or early Wednesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A warm afternoon in progress throughout as shearing upper trof and moisture challenged cold front push out of the eastern Great Lakes. Based GOES 16 and sfc observations, front is now crossing Lake Erie. Temps are well into the 60s north and into the lower 70s south in moderate southwest boundary layer flow. The front will cross central and north central PA through this evening with little more than a wind shift to the west and sct high clouds. 1026 mb sfc ridge over eastern TN will build northward towards the Ohio Valley overnight, providing mostly clear skies overnight. Mins will range from near 40F northwest to the upper 40s southeast. Decent radiational cooling will allow for valley fog to form again on Friday morning. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Strong upper ridge expands northward from the Ohio Valley on Friday...with large scale subsidence leading to another sunny day across central PA. 925mb temps of around 14C should translate to max temps in the upper 60s and low 70s. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
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Both the 12Z ECENS and NAEFS maintain an anomalous upper level ridge over the area through the weekend. This should ensure fair weather with above average temperatures Saturday to Sunday. Ensemble mean 925/850 temps support highs of 70-75F, while light wind and dry air result in seasonably cool nights. All medium range guidance indicating there will be a digging northern stream trough early next week over the upper midwest and Miss Valley that will eventually phase with closed low lifting out of the southern states. Considerable model difference exist with respect to timing/track of this southern stream shortwave, resulting in arrival of showers as early as Monday or as late as Tues PM. For now, have slowly ramped up the chance of rain beginning late Monday. However, will reserve the best chance of rain for Tuesday/Tues night, when bulk of med range guidance track shortwave and attendant plume of Gulf of Mexico moisture across the area. Early QPF estimates from operational runs and GEFS indicate 1+ inch amounts are possible. A period of near to below normal temperatures appears likely for the second half of next week, as upper trough swings east into the area. However, both GFS and ECMWF ensemble systems indicate the thrust of the chilly air will be directed west of Pa and there are indications of rising heights/milder weather across the entire eastern conus toward the end of the month.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/... VFR conds with surface wind gusts in the 15-20kt range over the western 1/2 of the airspace through the afternoon. A dry cold front will push across the airspace this evening and early tonight accompanied by a directional wind shift from 220-260 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-Tue...VFR to MVFR. Showers likely. LLWS. Strong FROPA. Wed...MVFR with shwrs likely. && .CLIMATE... Month-to-date, October 2017 is the warmest October on record at Harrisburg and Williamsport. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir NEAR TERM...DeVoir SHORT TERM...DeVoir LONG TERM...Fitzgerald/Ceru AVIATION...DeVoir/Steinbugl CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.