Area Forecast Discussion
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000 FXUS61 KPBZ 260508 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1208 AM EST Sun Feb 26 2017 .SYNOPSIS... High pressure will build in today. A weak crossing disturbance is expected Monday before a warm front moves north across the area Tuesday. A late Wednesday cold front will return wintry weather for the last half of the week. && .NEAR TERM /THROUGH TODAY/... Broad upper troughing, and some lake and terrain enhancement should keep scattered to numerous snow showers N of PIT and in the PA/WV/MD ridges overnight. Scattered flurries are expected elsewhere. Snow should end by morning as high pressure builds in and the flow backs SW. Expecting a clearing trend today also under the building high. Temperatures are expected to be near the seasonal average. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... Surface high pressure will begin to shift eastward early in the short term period. This will mean dry and relatively clear conditions will quickly be replaced by increasing cloud cover on Sunday night. With a fairly linear jet streak parked directly overhead the CWA slowly beginning to migrate eastward into Monday, a weak H5 vort looks to traverse the Ohio Valley on Monday. Weak warm advection ahead of it may be just enough to generate a shower or two through the day Tuesday. Some soundings indicate that a brief window of snow may be possible at the onset due to wide surface dewpoint depressions and low wet bulb zero heights, however very light qpf expectations combined with warm advection and no support for below freezing temperatures should preclude any possibility of accumulation should this occur. With the northward migration of a warm front through the area on Tuesday, temperatures during the short term look to return to above normal yet again. Fries && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A brief dry interlude follows th weak system from Tuesday before much higher PWATs follow for later Tuesday night into Wednesday night. A couple of successive waves look to pass the region in deep southwesterly flow. Some heavier rainfall may be possible with these given PWAT values running up toward 1.3 inches and a nicely couple jet structure to accentuate ascent. A trailing cold front will pass the area on Thursday. This will set temperatures into a free fall with model and ensemble consensus 850 mb temperatures falling into the negative teens Celsius. This should bring lake and upslope snows back into the picture. Additionally, some model indications exist of a weak system dropping through the Ohio Valley on Friday in the colder air. This could end up being a modest snow maker somewhere in the region depending upon its track. The extended forecast was generally favored colder than the SuperBlend guidance from Thursday night through Saturday due to the amplitude of the pattern and magnitude of cold air set to advect into the region. Fries && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... Westerly wind gusts of 25-35 knots will slowly subside with time, falling to 20 knots or less overnight for the most part. Ceilings will generally fall into the MVFR or low VFR range through the night and past sunrise on Sunday. Scattered snow showers, particularly north of I-80 and along the ridges, may produce brief localized IFR restrictions tonight. VFR conditions will take hold at all terminals by late morning Sunday as high pressure builds in. Winds will remain from the west, but fall in the range of 10 to 20 knots. .OUTLOOK... Occasional restrictions are again possible as the unsettled weather pattern is maintained for the first half of the week. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.