Area Forecast Discussion
Issued by NWS State College, PA

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102 FXUS61 KCTP 240050 AFDCTP Area Forecast Discussion National Weather Service State College PA 750 PM EST Mon Jan 23 2017 .SYNOPSIS... A strengthening storm will move east of the NJ coast tonight and early Tuesday. High pressure and unseasonably mild conditions will briefly return for midweek before a pattern change brings colder temperatures and lake effect snow to close out the month. && .NEAR TERM /UNTIL 10 PM THIS EVENING/...
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Impressive dynamic cooling led to rapid changover to sleet and snow from portions of the Laurel Highlands to the Central Mountains late this afternoon and early this evening. A quick one to two inches of snow and sleet produced high impacts on area roadways and long commutes for many. Dry slot has spread northward from the Mason Dixon line...and moderate to occasionally heavy precip has correspondingly lifted into north central PA at mid evening. Precipitation rates from the Laurel Highlands to the Central Mountains has decreased markedly...with regional radar mosaic indicating just pockets of moderate precipitation which is producing areas of sleet/snow. When the precip is lighter, it`s mainly light rain. Earlier expansion of Advisories from Blair County NWD through Centre and Lycoming Counties will remain in place for the next few hours...and we may end up discontinuing for the overnight with the late evening update. Maintaining previous timing and character of forecast...and slightly scaled back snow/sleet accums following the arrival of the dry slot. A longer duration snow accumualation is expected north of Interstate 80 where a general 4 to locally 8 inches of snow and sleet should accumulate by early Tuesday morning. CAMs are seeming to back off on a second surge of mid/upper level energy earlier expected to move NWWD over much of central and eastern PA after midnight...which could produce another organized period of snow/sleet. Will evaluate the progress of this potential feature while will play into decisions to drop or extend overnight advisories across the Central Mountains.
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&& .SHORT TERM /10 PM THIS EVENING THROUGH 6 AM TUESDAY/... Ongoing winter storm overnight for Central PA, with biggest impacts shifting to the NE portion of CWA. Best dynamic cooling and highest QPF impacts areas north of I-80 from mid evening onward, though a band may extend from KIPT SW back toward KUNV/KAOO that may produce a couple of inches of wet snow if it gets intense enough. Transition to snow should be complete by mid/late evening in the NE, and high precip rates should produce a couple hours of snowfall rates of 2" per hour - so warning area still looks good. Precip looks to become light over the SW this evening with any significant snows ending with a general light snow persisting much of the overnight. Primarily a rain/snow mix late in the SE. && .LONG TERM /TUESDAY THROUGH MONDAY/... Winter storm impacts over North-Central/Northeast PA will come to an end by Tuesday afternoon as strong surface low continues to lift northeast along the Mid Atlantic/New England Coast. Strong WAA pattern quickly follows into mid week with high pressure ridge axis crossing the area on Wednesday. Maximum temperatures on Wednesday are fcst to climb well-above normal for late January. A well-advertised pattern change remains on track from the second half of the week into the weekend, with high confidence in a long wave trough carving out over the Eastern U.S. This will result in a prolonged period of seasonably cold temperatures and lake effect/high-terrain snow showers during the remainder of the period. Several inches of snow is probable in the typical locations like the Lake Erie Snowbelt. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/...
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A storm moving up the Mid Atlantic coast will bring a mixture of rain and snow to central Pa overnight. Latest GLMP MELD suggests the higher terrain airfields, including BFD and JST are very likely to experience IFR/LIFR conditions with predominantly snow overnight, while the lower elevation airfields, including IPT,MDT and LNS should predominantly rain and MVFR conditions. In between, AOO and UNV are experiencing IFR conditions with snow at 22Z, but improvement is possible late tonight, as precip lightens up and potentially transitions back to rain. Improvement on Tuesday as storm lifts to the NE and precip comes to an end. Improvement arrives first over the SE half of CWA, though MVFR likely continues through the day. Outlook... Tue...Rain/snow ending in the morning. Widespread sub-VFR will improve for SE half by aftn. Wed...Low cigs/rain possible western 1/2. Breezy late. Thu-Fri...MVFR/IFR in rain/snow showers west. MVFR to VFR east.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 7 AM EST Tuesday for PAZ005- 010>012-017>019-025-026-045-046. Winter Storm Warning until 10 AM EST Tuesday for PAZ006-037- 041-042. Winter Weather Advisory until midnight EST tonight for PAZ024- 033. && $$ SYNOPSIS...La Corte NEAR TERM...DeVoir/Lambert SHORT TERM...RXR LONG TERM...Steinbugl AVIATION...Fitzgerald

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