Area Forecast Discussion
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000 FXUS61 KPBZ 262202 AAA AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 502 PM EST Sun Feb 26 2017 .SYNOPSIS... High pressure will bring clearing skies this evening. Rain chances return with a weak crossing disturbance Monday, and with a Tuesday warm front. A late Wednesday cold front will return wintry weather for the last half of the week. && .NEAR TERM /THROUGH MONDAY/...
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500pm update...Only very minor changes to previous forecast. Most noticeable will be the modifications in sky cover later this evening over the south. Sped up the onset of mid-clouds in line with latest operational and hires guidance. Temperatures were adjusted with the latest guidance as well. Previous discussion... Mostly clear skies will carry into the night under high pressure at the surface. Increasing southwest flow aloft will advect moisture back into the region by Monday morning. This will first manifest as high clouds residing across our southern zones by daybreak. Low to mid-level moisture catches up by midday monday, and increasing isentropic lift should provide enough support for showers to develop. Could see a light mix right at the onset of the showers, but with dew points and temperatures increasing quickly, rain will be the dominant precipitation type. Will continue to cap PoPs at chance as the warm front is transient and the upper-level moisture quickly evacuates eastward. TAx
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Warm advection generally characterizes the entirety of the short term forecast. The weak warm front that will have moved northward on Monday will continue its northward migration on Monday night. The area should enter the warm sector on Tuesday. This will result in well above normal temperatures returning to the area. However, the regime this week is far different when compared to last week. Whereas ridging was present almost all of last week, this week will be characterized by deep high speed southwesterly flow aloft. As such, with substantially higher PWATs in place and ill-timed short waves embedded in the flow, fairly quick hitting and copious rain-making showers will be likely throughout the short term period. By the time Wednesday rolls around, the large scale pattern looks to evolve such that the upper trough that will have been anchored to our west will start to eject eastward. This will drive a surface front toward the CWA by Wednesday night. Decent instability is present with the front as well as very strong 0-6 km shear. As such, some gusty storms will be possible, however given the lack of consistency on the frontal timing, it`s probably a bit early to accurately assess severe potential. Fries && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Cold advection will be underway as the cold front drives through and exits the area on Wednesday night. Timing amongst the guidance has become more spread as compared to previous model cycles, so while confidence in the passage is still high, timing is not. However, all areas look to be cold enough in the majority of the atmospheric column to support snow shower chances in northwesterly flow by Thursday. Guidance continues to favor a wave dropping toward the area Thursday night into Friday with decent enough agreement between the GFS and ECMWF to run with likely PoPs during that juncture. Still with the 12z runs today, the column maintains a cool enough profile with its passage to support all snow, and given the QPF and temperature fields, an accumulating snow somewhere in the region does now seem likely. Moderating temperatures and drier conditions will be favored toward the weekend as the upper trough that will have resided over the area late in the week starts to lift out. Fries && .AVIATION /22Z SUNDAY THROUGH FRIDAY/...
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VFR forecast overnight, as high and mid clouds will slowly increase from the southwest. A warm front will bring MVFR clouds to the area Monday morning. There is a risk for showers with the boundary, but have decided to leave out mention with current forecast due to the scattered nature expected. Any showers that do fall, are not expected to bring restrictions. .OUTLOOK... Restrictions will be possible again Tuesday morning as the next weather system impacts the region.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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