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000 FXUS61 KPBZ 221730 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 130 PM EDT Sun Oct 22 2017 .SYNOPSIS... High pressure will maintain dry and warm weather this afternoon. Rain can be expected with a Monday cold front and eventually a change in our weather pattern. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Brought high temperatures down a degree or two considering hourly trends so far this morning. Dry and warm weather again today, as southwesterly flow aloft continues to funnel high cloudiness over the area. High temperatures will be about 15 degrees above the average. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... Ensemble solutions have moved toward the slower operational models for the onset of showers on Monday. This slow down is in response to the development of a cutoff 500mb low over the lower Mississippi valley Sunday night. This upper low is slowing height falls over the region, and is holding back the eastward progression of large scale ascent. Additionally, the deep moisture stream will be slowed, as it squeezes northward between the upper low and the exiting ridge. Have slowed the higher PoPs a few hours on Monday and am thinking that the main rain shield will not make it across the entire area until late in the afternoon or evening. As the southern 500mb low slowly heads northward on Monday, northern stream energy will quickly dive southwestward from the Northern Plains toward the Upper Midwest. By late Monday night, a phasing will occur between the northern and southern energy, allowing for a rapid intensification of the energy rushing into the Upper Midwest. This will lead to an increase in rainfall rates and coverage just ahead of the upper level system and along its corresponding surface front. As the upper level system deepens Monday night, a surface low will develop along the cold front and move rapidly northeastward over Lake Erie early Tuesday morning. This should speed up the forward speed of the cold front meaning the heaviest rain should occur sometime between 06z and 18z on Tuesday. Trough will cutoff Tuesday afternoon, slowing it`s forward speed and causing it to lag well behind the exiting surface front. Much drier and colder air will quickly rotate around the southern flank of the 500 low, which will precipitate the development of a large dry slot, ending most of the showers by Tuesday afternoon. Much colder air will overspread the region Tuesday afternoon, which will cause a noticeable decrease in surface temperatures. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A lull in precipitation will continue Tuesday night under the expanding dry slot. The main trough axis will bring additional showers Wednesday and a continuation of the strong cold air advection. The weather should then dry out for Thursday and Friday before another low pressure system drags a front across the region over the weekend. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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VFR conditions will continue through tonight as high pressure departs, although clouds will start to thicken and lower with time. Low level wind shear is a possibility overnight, especially if surface wind can decouple, but did not have enough confidence to include at this time. Ceilings continue to lower and rain arrives in Ohio after 12Z, possibly starting at PIT/HLG by the end of the TAF period. Southerly wind will back towards the southeast tonight. .Outlook... Restrictions are likely through at least Monday night in widespread rain and low ceilings. Periodic restrictions should continue through Wed with an upper trough.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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