Area Forecast Discussion
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000 FXUS61 KPBZ 211619 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1119 AM EST Tue Feb 21 2017 .SYNOPSIS... A weak system will pass the region late today with a chance of some showers, however warm conditions will continue through the week. && .NEAR TERM /THROUGH TONIGHT/...
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Continued with little change to the overall forecast for now. Band of prefrontal rain extending from Michigan into Indiana/Illinois is shrinking with time. This is not surprising given the waning support for lift from the shearing shortwave crossing the Great Lakes. Have continued with slight chance PoPs for the afternoon/evening, but may increase if rain shows more vigor later. Dry mid-level air noted on 12Z PBZ sounding is mixing down and lowering surface dewpoints, and so have decreased those in the grids through the afternoon. Temperatures on track for the most part and only made minor tweaks there.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... Nearly zonal/flat ridging will support fast moving shortwaves through the flow through Thursday. While most of the support for any precipitation should remain well north of the region, increasing moisture in w-sw flow may lead to widely scattered showers until the more amplified low pressure system ejects into the Plains and lifts a warm front across the upper Ohio Valley. Generally kept chance PoPs through the period based on the uncertainty in guidance and lack of deep moisture and lift. With little modification in 850hpa temperatures, expect values to remain 20+ degrees above seasonal averages. It still looks like one our warmest days this week will be Friday, as most ensemble guidance has over 70 degrees here at Pittsburgh. The only thing that could hamper this would be cloud cover and any shower coverage. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... Models continue to slow the progression of the strong cold front, with it`s current timing progged for early Saturday. 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 the end of the forecast period, with another system progged for passage in the deterministic guidance. Seasonal temperatures will continue through the start of the work week. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... VFR can be expected through much of Tuesday although extensive high cloudiness will mar the sky. Sfc wind will veer to the south by daybreak as sfc high pressure gives way to an advancing trough. Some restrictions will start to edge in from the north on Tuesday night as a weak system shifts through the Great Lakes. High uncertainty exists on exactly how much shower activity will remain as it gets to our region as well as the degree to which ceilings and visibilities may fall as it passes. .OUTLOOK... Restrictions are likely with a Friday night/early Saturday cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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