Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 301154 AFDCTP Area Forecast Discussion National Weather Service State College PA 754 AM EDT Fri Sep 30 2016 .SYNOPSIS... Showery conditions will prevail today and tonight, especially across the southern half of the state. Unsettled weather with occasional light rain showers will persist through the weekend with a gradual drying trend by early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Two primary area of showers will continue through this morning, mainly across southern and eastern portions of the forecast area. The first plume of showers on a SE to NW axis across south-central PA and the Laurel Highlands coincided with a strong 45 kt serly LLJ, and enhanced upper level divergence/uvvel within the thermally direct cell associated with the right entrance region of a 90 kt/300 mb jet. The second area of mdt to hvy rain was being created by a similarly strong, nearly 4 sigma, 40-45 kt easterly 850 mb jet off the Atlantic transporting very high, 2-2.5 inch PWAT air over the coastal front. Heaviest rainfall rates of 2-5 tenths of an inch per hour per Dual Pol DPR product estimates are seen across the western Poconos and portions of the Lower and Mid Susq River Valley. The latest...07Z run of the HRRR tracks this area of enhanced moderately heavy rain NWWD across the Middle and West branch valleys of the Susq and north-central mtns during the mid to late morning hours...before carrying it north of the PA/NY border by 14Z, leaving mainly scattered showers across the CWA for the midday and afternoon hours. Outside of these primary rain areas, look for overcast skies with brief...scattered showers along with areas of drizzle and fog at elevations AOA 1800 ft MSL. Temps to start the day will be in the low-mid 50s in most locations. Winds will persist from the east to northeast at 8-12 kts. The Large low will be quasi stationary and will continue to stream moisture into Southwestern PA through much of today. Strong E-SE LLJ and above normal PW along with associated forcing on east/southeast side of upper low favors scattered to numerous lighter rain showers through the period across the Laurels. The highest rain chances this afternoon will once again be focused across the SE half of the state, but should be generally light and under 0.10 per hour, with 10-hour basin average amounts mainly under 0.25 of an inch. Afternoon max temps will only reach the upper 50s across the higher terrain of the north and west...and lower 60s throughout the valleys of central and southern PA. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Greatest deep layer convergence appears to become focused across the western mtns of PA tonight and early Saturday...before shifting into Central PA for the late morning and afternoon hours Saturday. Expect to see rather low coverage of showers at any one time. However, a few narrow north-south bands of mdt showers should shift gradually east across the region during the day Saturday, bringing additional light 12-hour rainfall amounts of 2 tenths or less to many locations. A few locations could see over one half of an inch where an hour or so of training showers occur. Will follow the cooler EC and NAM guidance for max temps ranging from the upper 50s across the mid 60s in the Susq Valley on Saturday. GFS MOS guidance looks to be up to several deg too warm considering solid overcast and persistent llvl easterly flow. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... GEFS and latest operational models track the initially cut-off upper level low slowly northward from the Lower Ohio Valley to southern Lake Huron during the 12z Sat to 12z Sunday period. The low will slowly blend into the upper level northwesterly flow over Sern Canada Sun-Mon and cold air advection will filter into the region early into next week. The final vestiges of the low that has dominated our weather pattern this week will finally slide off the New England coast by the middle of next week thanks to an upstream amplifying trough over the central CONUS. High pressure should regain control of our weather here in PA for Tue into early Thursday. The 00Z GEFS appears to be in close agreement with the previous 12Z GFS and EC with a path of Hurricane Matthew from the Bahamas to near the Outer Banks of NC during the 12Z Wed to 12Z Friday timeframe. The main concern here in Central PA would be a period of enhanced...deep easterly flow, clouds and perhaps a few periods of rain late next week...before the storm begins to drift NE and away from the Carolina and Mid Atlantic Coast. Temperatures will be slightly below normal through the weekend, before shifting to slightly above normal by the middle of next week...then possibly dipping back to near normal as clouds (at least the mid and high variety) thicken-up to the NW of Matthew. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... Widespread MVFR-IFR conditions through tonight. Pockets of RA/BR/DZ early today followed by decreasing pcpn coverage into the afternoon. Outlook... Sat...MVFR-IFR cigs. Ocnl -RA. Sun...MVFR cigs. Chc -RA. Mon-Tue...Gradual improvement likely. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/Steinbugl NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...Lambert/Steinbugl AVIATION...Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.