453 FXUS61 KCTP 301146 AFDCTP Area Forecast Discussion National Weather Service State College PA 646 AM EST Wed Jan 30 2019 .SYNOPSIS... An arctic air mass will move in today, dropping the temperatures and kicking up the wind. Bitter cold and brisk conditions are expected into Thursday night. Slowly moderating temperatures are expected late this week. A light to moderate snowfall is possible on Friday for southern PA due to an Alberta Clipper, with the highest accumulations in the Laurels. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Front seems to be thru KPIT and should arrive in JST by 8 AM. Snow showers at BFD dipped them down to just under 2sm, and it looks like they are right under the sfc low at this time. The front is lighting up the PBZ radar with a solid line of SHSN. Vis dipped to 1/4sm at KPIT, and wind gusted to 28KT. This is generally what we are expecting for the front as it passes thru this morning and early aftn. Still mainly clear in the east, so some sunshine will help destabilize things there. That will likely serve to make the snow showers/squalls more intense there. Might even be a CG or two with CAPE nearing 100J in the east between 10AM-1PM. Most likely place for thundersnow is near wind turbines. CAPE will be nearly nil for the western half of the CWA due to early passage. Air is very very dry, with dewpoints sub-zero over half of the area, and dropping thru the single digits elsewhere. The lack of moisture and fast movement of the front will spell only very minor accums (at most an inch for most of the area). The fluffiness of the snow may yield an isolated >1" report or two. Temps continue to dive over the NW, with temps falling 5 to 10F thru the daylight hours. There will be just a brief rise in the SE, with maxes in the m20s before FROPA. Wind gusts along/behind the front could touch wind advy criteria (40KTs) briefly on a the highest hill tops. But, gusts into the 30s will be much more common. The front and any remaining squalls will be off to the east of the CWA at 1 or 2 PM. The wind chills then really dive. Have adjusted the start times of the wind chill advy, delaying the start time for the going area, and introducing a new advy for the entire SE - where WCs will get to 10 or 15 below tonight. The advy threshold there is only 10 below, with 15 below elsewhere. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Big high pressure bump rolls in with sfc flow generally anti- cyclonic tonight. The lake effect snow trajectories are focused to the north of CTP CWA, but will leave a very minor chc in the far NW part of Warren Co tonight and Thurs. The worst of the cold and wind chills will probably be tonight/Thurs AM. Temps stop their slide on Thursday, but maxes will still only be close to zero at BFD. Mid teens will be the best the SErn cities can manage even with a downslope and an abundance of sunshine. Record low max temperatures are in jeopardy on Thursday. Have trimmed off the WC advys for the SE half of the area around noon Thurs as temps rise and then the wind slows later in the day. The warning may even be able to be downgraded to an advy in the aftn, as current AppT grids do not drop back to 25 below, even Fri morning. But, that can be done at a later time as temps get more refined with the next few shifts. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... *Warming trend starts this weekend (Groundhog Day) *Monitoring potential ice jam threat next week Min temperatures Thursday night -15 to -30 degrees below average with the anticyclone right overhead. Models continue to spread snow from a clipper into the SW around sunrise Friday and make a light coating over the southern tier counties on Fri. Highest confidence is over the Laurel Highlands which tend to do quite well based on projected low track. Expect SLR of 20:1 in retreating arctic airmass supporting potential for max snow amounts in the 3-6 inch range on the Laurel ridges, 1-3" SC mtns and ~1" in the Lower Susq. The frigid cold will lead to ice forming on area rivers and streams through late week. A significant warming trend (relative to the well-below average mid-late week temps) is expected to begin on Saturday (Groundhog Day) and continue into early next week. We will need to monitor potential for ice jams and localized flooding as temperatures rebound into the 40s. Confidence is low with regard to timing/extent of possible light precip (mainly rain) events next week. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Updated the TAFS here just after 4 AM. Main change was to adjust timing of snow showers, as the second push of cold air works from west to east this morning into early this aft. Very brief snow showers and perhaps a few brief squalls will be possible. The main issue will be the wind and cold, as winds pick up later this morning. Winds and cold temperatures will persist into Thursday morning. Outlook... Thu...Windy. MVFR cigs/snow showers NW, Mainly VFR SE. Fri...Restrictions poss SW half in light snow. Sat-Sun...VFR. && .CLIMATE... Bitterly cold temperatures are expected for the second half of the work-week. Here are some record mini-maxes and record minimum temperatures for central PA climate sites for Wednesday (1/30) and Thursday (1/31): Record minimums on Wednesday, 1/30: Williamsport: -6F (1948) Harrisburg: 2F (2014) Altoona: 2F (2014) Johnstown: -9F (1963) Bradford: -14F (1965) Record mini-maxes on Wednesday, 1/30: Williamsport: 12F (1934) Harrisburg: 13F (1934) Altoona: 11F (1966) Johnstown: 9F (1934) Bradford: -1F (1977) Record minimums on Thursday, 1/31: Williamsport: -14F (1948) Harrisburg: 2F (1948) Altoona: 0F (1977) Johnstown: -8F (1977) Bradford: -13F (2010) Record mini-maxes on Thursday, 1/31: Williamsport: 15F (1971) Harrisburg: 20F (1966) Altoona: 13F (2004) Johnstown: 12F (1966) Bradford: 2F (1971) && .CTP WATCHES/WARNINGS/ADVISORIES... Wind Chill Warning until 9 AM EST Friday for PAZ004>006- 010>012-017-018-024-033-037-041-042. Wind Chill Advisory from 5 PM this afternoon to noon EST Thursday for PAZ036-046-049>053-056>059-063>066. Wind Chill Advisory from 1 PM this afternoon to noon EST Thursday for PAZ019-025>028-034-035-045. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Steinbugl AVIATION...Martin CLIMATE...