Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 240517 AFDCTP Area Forecast Discussion National Weather Service State College PA 117 AM EDT Mon Oct 24 2016 .SYNOPSIS... A cold front and potent disturbance aloft will pass through tonight and early Monday bringing a cold rain to the northern half of the state. A reinforcing shot of cold air will follow and last through mid week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Weak sfc low located over the northwest mountains early today... will traverse the rest of the North Central and Endless Mountain region in the pre dawn hours...spreading showers along and north of the I80 corridor through 12z. . Energetic system aloft with broad upper level diffluence associated with the left exit region of a 110 kt 300 mb jet...and strong southwesterly 925-850 mb theta-e advection will bringing a stripe of rain of light to moderate rainfall (0.10-0.25") across the northern third/quarter of the CWA (with maybe around 0.4" along the NY state line), while a sharp gradient to lower amounts (or no rain at all) will occur just to the north of Interstate 80. Will keep a few hundreths in the QPF grid in the central mtns for 06-12z. NW flow will make isold-sct shra in the Laurels in that same time frame. POPs will be near zero overnight across the southern mtns and Lower Susq Valley. Temps will be cooler and in the 40-45F range for overnight lows across the north where the steadier rain falls (and cfropa occurs earlier), while mins in the south will be mainly in the upper 40s.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... NW post-frontal flow will keep isold-sct shra for the usual suspects on Monday. High pressure stays to the W thru the short- term and the tight pres grad will keep it breezy. Temps will only rise 6-8F on Mon in the NW, and 10-15F in the SE under constant but weak cold advection. The flow lasts into Mon Night, and the temps get cold enough then to get a mix or plain ol` --sn for precip type in the higher elevation of the nrn mtns. As with last night, no accums expected with still-warm ground and very light/sct precip. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Surface high pressure gradually works in from the Great Lakes Tue into Wed keeping below normal temperatures in place. Cyclonic flow/cold air aloft on Tue may bring enough instability to kick off a few light showers in the NW mountains. CAA comes to an end on Wed as weak progressive upper ridge moves through as low-level flow turns back to the S/SW. Could see a decent frost Wed morning as dewpoints bottom out. A compact low developing over the Midwest will already be knocking on our door by Thu. Drier air remains in place over the east Wed night, but expect showers to work into the west overnight. Rain becomes likely for much of the area on Thu. Model guidance continues to diverge after that, especially at the surface, so confidence in next weekends forecast remains rather low. But a look at the upper pattern suggests general NW flow keeping a steady stream of cooler air feeding into the region, with a series of shortwave troughs sliding through. && .AVIATION /05Z MONDAY THROUGH FRIDAY/... A fast-moving low pressure system tracking across Northern Pa will bring a period of showers and sct tsra to that part of the state overnight. A core of strong winds aloft will precede this system, likely resulting in LLWS overnight across much of Central Pa. The exception may be at KJST, where climatology and model soundings suggest the strong winds will mix to ground level, resulting in wgusts to near 35kts. The threat of LLWS should end from north to south after midnight, as strong winds aloft slip south of the state. The other concern will be the possibility of low cigs overnight at KBFD and KJST, as plume of low level moisture ahead of trailing cold front ascends the higher terrain of West Central Pa. Model soundings indicate a possibility of tempo IFR cigs at KBFD between 04Z-12Z and at KJST between 08Z-14Z. Moisture flowing off of Lk Erie will produce fairly widespread stratocu across Central Pa on Monday. Model soundings suggest MVFR cigs could linger most of the day at KBFD/KJST, while predominantly VFR conds expected elsewhere. Outlook... Tue...No sig wx expected. Wed...Patchy AM fog possible. Thu...Rain/low cig possible. Fri...MVFR/sct -shra N/W. VFR elsewhere. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo/Lambert NEAR TERM...DeVoir/Lambert SHORT TERM...Dangelo LONG TERM...RXR AVIATION...Fitzgerald is the U.S. government's official web portal to all federal, state and local government web resources and services.