Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190541 AFDCTP Area Forecast Discussion National Weather Service State College PA 1241 AM EST Thu Jan 19 2017 .SYNOPSIS... Building high pressure will provide 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 THIS MORNING/... Another night spent under the blanket of low clouds and fog...as lowering inversion will keep llvl moisture trapped beneath it for much of central PA. Nearly calm wind promoting fog formation again...with most areas between 2 and 4sm already. Patchy dense fog is a possibility in the pre dawn hours. Mins will be fairly homogeneous...ranging from the lower to middle 30s throughtout... which is nearly 15F above normal. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... 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 /FRIDAY NIGHT THROUGH WEDNESDAY/... 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. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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06Z TAFS sent. Strong inversion will keep low clouds around the area overnight. Some minor changes made. Earlier discussion below. High confidence that blanket of low clouds will continue through the overnight with IFR restrictions persisting over the west and MVFR for much of the central and the east (though KUNV/KAOO may dip to IFR for a couple of hours bracketed by sunrise as inversion continues to lower. Other concern with plenty of low level moisture trapped will be potential for fog. Winds becoming light will promote formation of fog, with most areas settling between 2-4sm. High pressure building in for Thursday will finally mix enough drier air down from aloft to erode clouds - initally breaking in the SE starting mid morning and spreading to the NW by early/mid afternoon. 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... Fri...Restrictions developing early. Rain/Snow north and rain south early. Rain areawide in the afternoon. Fri night...Widespread restrictions in areas of drizzle. Sat...MVFR/VFR cigs. Sun...Widespread IFR/MVFR restrictions. RA advances fm S-N. Mon...Widespread IFR restrictions in -RA. LLWS poss.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...Dangelo LONG TERM...Lambert/Gartner AVIATION...Martin/RXR

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