Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 201724 AFDCTP Area Forecast Discussion National Weather Service State College PA 124 PM EDT Fri Oct 20 2017 .SYNOPSIS... A large and persistent area of high pressure at the surface and aloft 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 and potent upper level disturbance pushing through Pennsylvania Tuesday or Tuesday night preceded and accompanied by periods of rain and perhaps a narrow band of gusty thunderstorms Tuesday afternoon and evening. && .NEAR TERM /THROUGH TONIGHT/... Aside from a few wisps of cirrus over the region, full sunshine is being enjoyed throughout central PA this afternoon. Clear skies will continue tonight as strong upper ridge expands northward and center of 1024 mb sfc high slides across central PA. Light wind will allow mins to drop into the 40s everywhere with a few upper 30s likely across northern and central valleys around sunrise. Patchy valley fog will be seen once again a few hours surrounding daybreak. && .SHORT TERM /SATURDAY/... Little change in store for Saturday as anomalous upper ridge delivers yet another splendid autumn day. Abundant sunshine will allow temps to warm through the 70s most places. Southern areas could approach the upper 70s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Upper ridge to start the period with warm days and seasonably cool nights. All medium range guidance indicates that there will be a significant digging northern stream trough that will eventually take on a slightly negative tilt early next week as it moves from the upper midwest and Miss Valley to the Appalachian Mtns and Carolina Coast. Models have converged to indicate the center of the significant rainfall event occurring late Monday through tuesday evening when widespread rainfall amounts of 1-1.5 inches is anticipated. As the cold front pushes east through the commonwealth Tuesday into Tuesday evening, Sfc-850 mb Lifted Indices go slightly Negative acrs parts of Scent PA and the Susq Valley. Pattern appears favorable for a Narrow Cold Frontal Rainband - NCFRB (with brief gusty winds) to push through the expansive shield of moderate to briefly heavy rainfall rates. Current forecast rainfall amounts pose little threat for any small stream flooding considering much higher short term FFG values. 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. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR will prevail through evening, followed by low confidence for terminal impacts in patchy late- night/early morning valley fog Saturday morning. VFR conds will prevail throughout Saturday. Outlook... Sat-Sun...Patchy AM valley fog otherwise VFR. Mon-Tue...VFR to MVFR/IFR. Showers likely; periods of heavy rain and gusty winds possible with strong FROPA. LLWS. Wed...Breezy. Sct showers. MVFR NW 1/2. Thu...No restrictions. && .CLIMATE... Month-to-date, October 2017 is the warmest October on record at Harrisburg and Williamsport. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Lambert NEAR TERM...DeVoir/Lambert SHORT TERM...DeVoir/Lambert LONG TERM...Lambert/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.