Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 222044 AFDCTP Area Forecast Discussion National Weather Service State College PA 344 PM EST Sun Jan 22 2017 .SYNOPSIS... A multifaceted storm will bring drenching rain, elevation- driven snow and gusty winds to Central Pennsylvania on Monday. 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/... Another day of wildly varying conditions across Central PA ranging from very mild spring-like weather in the Alleghenies where temperatures reached the upper 50s to low 60s, to cloudy, cool and foggy conditions with readings in the 40s from the central ridge and valley region into the lower Susquehanna Valley. The fog has been incredibly stubborn locally. POPS trend upward from south to north later tonight as moisture and lift increases ahead of the strong storm system tracking northeast across the Southern Appalachians. Latest HRRR shows rain spreading north of the Mason-Dixon line between 02-04z. && .SHORT TERM /10 PM THIS EVENING THROUGH 6 AM MONDAY/... Rain will increase in coverage and intensity from south to north through daybreak Monday. A tightening pressure gradient between deepening low pressure in the Carolinas and high pressure in eastern Quebec will produce strong/gusty east winds early Monday morning and continue through Monday afternoon. Issued a wind advisory for most of the lower Susquehanna Valley with max wind gusts 45-50mph. && .LONG TERM /MONDAY THROUGH SUNDAY/... All model data tracking closed upper low northeast across Virginia Monday. A steady rain will overspread Pa from north to south as strong upper lvl divergence, anomalous easterly low lvl jet/PWATS work into the state. Thermal profiles initially warm enough for rain everywhere. However, dynamic cooling associated with arrival of strongest forcing will likely result in a changeover to wet snow over the higher terrain of central Pa. Forecast soundings suggest the highest elevations of the Laurels/Northern Mtns could mix with or change to wet snow around midday. By later in the day, snow could become more than just a higher elevation threat, with thermal profiles even as far east as AOO/UNV cooling sufficiently for all snow. Limiting factor in terms of accumulation will be marginal boundary layer temps and warm ground. The threat is for several inches of heavy wet snow, especially favoring the higher elevations, across northern Pa. A winter storm watch has been issued for the northern counties, where 6+ inches appears possible, mainly over the higher terrain. Biggest threat across the Lower Susq Valley will likely be gusty winds, the result of tightening pressure gradient between approaching low pressure and high north of New England. Bufkit soundings indicate wgusts in excess of 40kts are likely across southeast Pa, as low lvl jet swings through Monday. Per coordination with LWX/PHI, have issued a wind advisory for this area. Lastly, still monitoring the potential for minor flooding. Target area for the heaviest rain is across the south central part of the state, where orographic forcing at nose of powerful easterly low level jet will play a role. Mean QPF from both SREF and GEFS max out around 1.5 inches in this region, which would be a beneficial rainfall. However, given FFG/FFH values around 2 inches, can`t rule out some minor flooding. The surface low will reach our latitude between about 6-12Z Tuesday, an old rule of thumb that dictated when the steady precip tends to taper off. Upper ridging will quickly build into the region later Tuesday into early Wednesday, bringing a short period of fair and mild wx. A pattern shift is advertised for the second half of the week as low pressure takes up residence over eastern Canada, and despite a tenacious ridge over the northern Caribbean and Bahamas, models carve out a long wave trough over the eastern US with a return to seasonable cold by the end of the week into next weekend. The ridge in the west and trough in the east is also usually a good one for winter storminess, but the deterministic ECMWF and GFS don`t show much more than a series of clipper type systems that promise an extended period of clouds and scattered mainly mountain snow showers that should continue through next weekend into the week after. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... Solid IFR-VLIFR continues across the central and eastern airfields while KBFD/KJST remain VFR conditions as of 22/20z. Will continue IFR or lower conditions at KAOO/KUNV/KMDT/KIPT/KLNS through tonight and into Monday. For KBFD/KJST will gradually trend lower tonight into early Monday morning with lowering cigs and rain reaching the southern airfields around 23/03z. Widespread sub-VFR is a near certainty through Monday as rain overspreads the airspace and mixes with/changes to snow in the higher elevations along the Allegheny Front. Strong gusty winds will impact southern airfields especially KMDT/LNS with 30-35+KT gusts early Monday at KMDT/KLNS. Outlook... Tue...Widespread sub-VFR with some improvement by aftn. Rain/snow ending in the morning. Gusty winds from NNW decreasing late. Wed...Low cigs/rain possible western 1/2. Breezy late. Thu-Fri...MVFR/IFR in rain/snow showers west. MVFR to VFR east. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Monday afternoon through Tuesday morning for PAZ005-006-037-041-042. Wind Advisory from 5 AM to 4 PM EST Monday for PAZ057-059- 064>066. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Fitzgerald/La Corte AVIATION...Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.