953 FXUS61 KPBZ 101624 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1224 PM EDT Wed Oct 10 2018 .SYNOPSIS... Today will be the last day of unseasonable warmth. Rain chances increase tonight ahead of a cold front, and continue through the passage of the boundary on Thursday. Much more fall-like temperatures will then take hold into the weekend. && .NEAR TERM /THROUGH MIDNIGHT/... An area of showers associated with a weak shortwave currently extend from central WV towards central Ohio. These showers will move northward over the next several hours. With little in the way of cloud cover this morning and early afternoon, temperatures have been able to climb well into the 70s and are expected to top out in the low 80s for much of the area. Showers will enter the southwest portions of the area over the next few hours, eventually making it to the Pittsburgh metro by late afternoon or early evening. Limited instability will preclude the threat of thunderstorms for at least the next few hours before lapse rates steepen a bit before the front approaches in the morning. && .SHORT TERM /MIDNIGHT TONIGHT THROUGH FRIDAY/... The models are in general agreement overall with the timing of the well- advertised frontal boundary that will bring a stark pattern change. The front will be in the vicinity of the Ohio river by 12Z Thursday and swing across the ridges during the early to mid afternoon hours. Have PoPs ramping up to categorical areawide overnight with good southwesterly moisture feed, and then tapering behind the front on Thursday. Kept a slight chance of thunder ahead of the front as lapse rates aloft steepen enough for some modest elevated instability. Severe weather is not a threat. Some efficient rainfall production is possible for a time with with soundings saturated to 10-12kft, warm cloud depths to match, and precipitable water values briefly reaching or exceeding 2 inches in spots. Thankfully, the overall progressive nature of the system will keep rainfall totals in check, so flooding will not be anticipated either. After one last warm and humid night, temperatures will not rise much on Thursday as the front crosses, with perhaps a non- diurnal afternoon drop across Ohio. Only a few isolated showers will remain along the ridges and near/north of I-80 by 00Z Friday in northwest flow and lingering low level moisture. These will wane by sunrise as moisture becomes more scarce, but some clouds may linger for a bit on Friday as surface high pressure noses in. Dropped high temperatures a few degrees from the previous forecast for Friday given lingering clouds and subzero 850 mb temperatures in northwest flow. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A general troughing pattern will linger through the extended period. Disturbances moving through this trough will provide some precipitation chances, but timing remains questionable. One such ripple moves through Friday night into Saturday, bringing some chilly rain showers. Better rain chances arrive with a frontal boundary, especially Sunday night into Monday. Things quiet down a bit by Tuesday. Temperatures will continue to run near or below normal through the extended period. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... VFR is expected through the afternoon under a high pressure ridge. A few showers are possible late this aftn as the ridge shifts E, and a weak shortwave in SW flow crosses the area. Widespread deterioration to MVFR and eventually IFR is expected tonight with the approach of a cold front. Outlook... Widespread restrictions are expected to continue Thu with FROPA. Restrictions are possible Thu night through Sat with cool NW flow and upper troughing, and again Sun with a crossing cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$