Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 182054 AFDCTP Area Forecast Discussion National Weather Service State College PA 354 PM EST Wed Jan 18 2017 .SYNOPSIS... High is building in and will bring mainly dry conditions for tonight and early Friday. Low pressure over the midwest will push a warm front north across the commonwealth Friday. A mild time is in store for the next several days. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Sun just poked through the clouds over Tussey Mtn and visible shots show expanding/more-numerous breaks in the downslope off the central ridge and valley region and into the lower Susq. We should see a little less cloud cover there until evening. Then, guidance shows that the inversion lowers, but lots of moisture will still be trapped underneath it - esp in the west and north. Will play the role of the pessimist here and call for the holes in the stratus to fill back in - at least in the central ridge/valley region. The wind will likely calm again over the ern valleys and stay 5-6kts over the mtns. Temps should fall off on a more-normal nocturnal curve tonight...but...mins will be about 15F above normal. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... Thurs should be a pretty nice day but still rather cloudy in the morning and early aftn for most of the CWA. SE will again be the nicest place with the downslope. Light W wind as the center of the high pressure stays to our S. Deep mixing is not foreseen as the inversion is still very strong/sharp. However, top of mixed layer temps in the 0 to +4C range crank out maxes in the u30s to u40s. Someone in the SE will probably crack 50F, especially if the stratus breaks up faster than currently expected. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
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1020 MB sfc ridge builds NE and over central PA and upstate New York Thursday night as a sharp upper ridge builds over the NE states (sliding from the spine of the Appalachians to the Eastern Seaboard by midday Friday). The main weather maker for early in this period will come in the form of a warm front that will lift north over the state during the day Friday. Operational model and EFS consensus us for a few periods of rain to occur Friday - primarily during the daylight hours as the nose of a 40-45 kt swrly LLJ helps to transport a few bands of relatively strong 925-850 mb Theta-E convergence over the state. Rainfall amounts should be between 2 and 4 tenths across much of the forecast area during the Friday period. The upper ridge is forecast to re-establish itself over the eastern U.S. over the upcoming weekend, bringing mild and mainly dry conditions Saturday, through at least the mid morning hours on Sunday. Daytime temperatures across most of Central Pennsylvania will be well above normal, but the departures for overnight lows should be greater by several degrees more throughout the entire extended period. Another wave approaches/lifts into the OH valley late in the weekend into next Monday. Again, temps could be marginal at the start of pcpn overnight Sunday for some ice or snow, but the bulk of pcpn looks to be rain at this point. However, some guidance, especially the ECMWF, is suggesting enough cold air may arrive at the end of the pcpn for wintry p-types across northern/northwester PA.
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&& .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... Holes finally appearing in the SE. Many locations now MVFR and should remain there until A) clouds SCT (SE half) or B) upslope brings them back into IFR later this evening or overnight. extensive cloud shield stretches all the way back into IL/WI. Inversion lowers tonight as high pressure moves in. Wind may go light/vrb overnight in the ern valleys, but most locations will continue to have a light W wind with the center of the high to our S. Have mentioned some light fog at most places tonight, but the biggest threat for IFR due to just fog is KIPT. Looks VFR for Fri except over the wrn mtns JST/BFD where it may take most of the day to break through the inversion and finally join up with the dry air aloft. Next trouble will be on Fri as the surface ridge gets squeezed and upper ridging is poked to the east by a strong short wave trough rotating poleward from a central CONUS upper cut-off. Warm advection will bring in clouds and deteriorating flying conditions into MVFR/IFR in the early morning SW and around noon in the NE. Outlook... Sat...Mainly VFR with MVFR cigs poss W. Sun...VFR AM then lowering cigs/vis. RA advances fm S-N. Mon...IFR/MVFR cigs/vis in -RA. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Lambert/Gartner AVIATION...Dangelo

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