Area Forecast Discussion
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000 FXUS61 KPBZ 211859 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 159 PM EST Tue Feb 21 2017 .SYNOPSIS...
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A weakening front may provide a few showers tonight and into Wednesday. More showers are possible starting Thursday afternoon due to a warm front. The unseasonable warmth will continue.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Decent upper moisture plume has led to thickening mid and high level cloud cover through the day. Prefrontal rain band continues to fall apart as upper level support wanes. The 500 mb shortwave which is helping to push the boundary is shearing out over the northern Great Lakes. The front will enter the region tonight, but will begin to break up as it becomes parallel to the increasingly zonal flow aloft. While weak southerly flow remains at the surface, much of the deep moisture will remain bottled up to our south. This, along with the general lack of lift, points to continued low PoPs tonight. Have 30ish values in place for most of the CWA overnight with the expectation of less than .10 inch over the area. Quite mild overnight, with low temperatures 5 to 10 degrees above the daily normal MAX values.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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Generally zonal flow continues into this period, with more amplified flow towards the end ahead of the strong system approaching Friday night. A few showers may linger along the dying boundary Wednesday morning, before flat ridging provides a dry interlude Wednesday afternoon through much of Wednesday night. Flow begins to amplify Thursday as a strong shortwave begins to dig over the Plains. The increasing southwest flow will push moisture and a warm front towards the region with time. Modest isentropic lift at 300/305K will also support chance PoPs for showers. Some modest instability of 300 J/kg or less is noted on model soundings, but elected to hold off on thunder mention for now. The unseasonable warmth continues through this period, with high temperatures consistently running 20-25 degrees above average. Made only minor modifications to numbers using bias-corrected guidance. See climate section for details on record high temperatures this week, some of which could be in jeopardy.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/... Warm front will lift north of the area Friday increasing southerly flow into the area. 12Z GFS continues the trend of slowing down the progression of the strong cold front late Friday into early Saturday. Delayed timing should allow for enhanced clearing in the warm sector, and as a result, temperatures will soar. Have kept with the trend of bumping up Friday`s highs, although not quite to the MEX numbers. Will continue with likely PoPs for this boundary, with a chance for thunder, though the overnight passage may be a bit of a limiting factor. Temperatures should return to near normal values, with snow showers as the system departs. Very broad troughing is then expected through early next week, with another system progged for passage in the deterministic guidance. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... VFR conditions expected to persist through the evening with high clouds on the increase. A low pressure system well north of the area will bring a weak cold front tonight. This boundary will result in little more than a few showers, but will lead to an increase in low-level moisture. This will manifest in lowering CIGs down to MVFR for most locations by Wednesday morning. A few locations (FKL/ZZV) could see brief spells of IFR as well. Any lingering restrictions mid Wednesday morning will see gradual improvement through the early afternoon. .OUTLOOK... Restrictions are likely with a Friday night/early Saturday cold front. && .CLIMATE...
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Record high temperatures for climate sites: Wed Thu Fri --------- -------- -------- PIT 70 (1922,30) 70 (1922) 70 (1875,1906) ZZV 67 (1992) 64 (2000) 70 (1961) MGW 70 (1980) 68 (1996) 75 (1975) DUJ 60 (1983) 63 (1985) 60 (1985) HLG 57 (1949) 62 (2000) 63 (2016) PHD 73 (1997) 69 (1975) 66 (1985)
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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