889 FXUS61 KCTP 150053 AFDCTP Area Forecast Discussion National Weather Service State College PA 753 PM EST Tue Feb 14 2017 .SYNOPSIS... A cold front pushing through in the morning will be accompanied by snow showers and a few squalls. Northwest flow will then bring lake effect and higher elevation snow accumuations into Thursday. Thursday will be the coldest day this week, but then the temperatures warm up significantly for the weekend and even beyond. && .NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/... Lower clouds invading from the north. The cold front is around Saginaw Bay at 00Z. The front will enter the far NW by 09Z, and SHSN will result. The gustiness of the winds will be of concern, but instability will likely be limited a little by the time of day. However, there is some lightning over central lower MI attm. So, there will probably be a few heavier squalls. Accumulations will be minimal overnight, as the showers will be moving quickly and moisture is minimal. The model data plays out a scenario where the gusty front comes through and the squalls will likely break up as they move down the Allegheny Front and espedcially as they move into the Susq valley. Clouds across the north and SW flow ahead of the front will make it tough for the temps to drop to freezing before the front arrives in the NW. This could make for icy roads as the snow may melt on the roads and then freeze up. && .SHORT TERM /7 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Latest HRRR runs show a decrease in moisture, however the strong 850 mb winds across the lake should provide enough moisture to enhance the bands though the latest model runs have weaker winds doe to a slackened gradient. However should still need to monitor potential for snow squalls tomorrow morning. Latest NAM Snow squall parameters following fropa shows decent CAA but has weakened with the latest runs though lapse rates remain fairly steep. Model guidance shows triple point low development near the New England Coast Wednesday afternoon/evening, with the new low rapidly deepening as it tracks through the Gulf of Maine into the Canadian Maritimes on Thursday. Northwest flow/cold air advection on the backside of the storm will support long- duration lake effect/upslope snow possible over the NW PA snowbelt by through Thursday night. Have held off on any headlines due to less moisture available to the system. So have highlighted possible snow squalls in HWO and lake effect snow. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... The first few days of the medium to long range period will feature a fairly well-aligned NW flow with below normal daytime temps (departures of minus 3-7F), and numerous snow showers and areas of heavier LES across the NW mtns and Laurel Highlands. Significant snow accum will likely occur over a fairly long duration, and snow accums will probably not reach heavy snow criteria of 6 in/12 hours. Thus, we decided against the issuance a LES watch for Warren/Mckean counties at this point. However, can easily see LES/Winter Weather Advisory criteria being met during respective 12-hour periods within the 12Z Wed through 00Z Friday timeframe. The deep, NE U.S. upper trough will lift off to the NE across the Canadian Maritimes by the upcoming weekend, followed by significant height rises via a full-latitude ridge (flattening out as it moves from the upper midwest to the New England coast by Sunday). Afterward...GEFS and EC guidance still indicates above normal 1000-500 mb thickness and 850 mb temps with a distinct split flow pattern across the central and eastern U.S. The passage of a weak northern stream trough that will bring a few periods of clouds and generally non-measurable sprinkles to the northern and western mtns later Saturday into Sunday, will be followed by yet another sharp ridge aloft and sprawling sfc high will bring fair and unseasonably mild air right through early next week, with little threat for measurable precip before the middle of next week. For Sat night through Tuesday night, overnight low temps (in the 30s Central and NW PA...to near 40F at times in the SE) will be consistently mild and near normal highs in the greater Harrisburg area, and as much as 8-10 deg above what we see at 2 pm in mid February across the NW mtns and Laurel Highlands. Daytime highs during this same period will vary from the upper 40s to near 50F across the NW mtns...to the mid and upper 50s in the SE (a whopping 15-20F above normal highs). && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... 00Z TAFS sent. Like the last 2 events, cold front and strong dynamics will trigger bands of snow showers along and just behind the cold front late tonight into Wednesday morning. Like Sunday night and yesterday, the airmass is not that cold (about the same), thus not looking at a large response from the Great Lakes. Snow showers will likely linger into Thursday night, as winds aloft remain northwest, and it will be rather cold aloft. Temperatures will moderate by the end of the week into next week, as high pressure moves off the east coast. VFR conditions will return to the area by Friday. IFR conditions will be possible with the snow showers, mainly at BFD and JST, prior to Friday. Outlook... Thu...Sct shsn/VIS reductions possible BFD/JST. Fri and Sat...No sig wx expected. Sun...Mainly VFR conditions. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/Ceru SHORT TERM...Ceru/Steinbugl LONG TERM...Lambert/Steinbugl AVIATION...Martin