Area Forecast Discussion
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323 FXUS61 KPBZ 260055 AAC AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 855 PM EDT Sat Mar 25 2017 .SYNOPSIS...
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Temperature well-above normal will continue into next week. Showers and thunderstorms are expected Sunday afternoon and evening.
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&& .NEAR TERM /THROUGH SUNDAY NIGHT/...
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The zonally-oriented warm front over swrn New York earlier this afternoon is in the process of reorienting itself meridionally in response to a closed H5 low/deepening sfc low pressure in Missouri. The narrow plume of showers associated with this boundary has diminished as the front oozes across the northern part of the forecast area, with reflectivity in the CWA seeming to be associated with virga or light sprinkles. The front will transect the forecast area tonight, leading to a non-trivial gradient in overnight temperature. The far eastern/northern zones could end up as cool as mid 40s overnight given the cooler/drier sfc observations noted upstream, while the swrn zones could end up in the mid 50s, if not warmer. Current showers and storms in association with the upper wave will make slow ewd progress during Sunday morning, leading most areas to remain dry for the first half of the day. The convection will move into eastern Ohio late morning/early afternoon and intensify modestly/develop ewd to near KPIT by early evening as the upper low opens and phases into the nrn jet stream. Hi-res, convection-allowing models, coarser operational synoptic models and text-based statistical forecasts all offer congruent timing signals that a loosely-organized convective line will be entering wrn Pennsylvania by early evening, likely affecting the Pittsburgh area in the 26/2300-27/0100 UTC timeframe. Instability profiles will be modest at best despite decent shear, so little storm structure or organized severe potential are expected beyond the rain. Showers and storms will develop ewd across PA Sunday evening, with only lingering light showers remaining west of the Laurels by Monday morning. Although a sfc cold front technically will accompany the departure of the upper wave, there does not appear to be much in the way of cold air at the surface associated with this feature. So there is not expected to be a dramatic drop in overnight temp Sunday night, with minima remaining in the lower 50s.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY/...
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While the bulk of the rain will move east by Monday morning, some lingering showers will remain possible. After a brief period of dry weather, a cold front crossing the region Tuesday will bring another round of showers. The precipitation with that front doesn`t look as organized as previous model runs, so have decided to stick with likely pops for now. Temperatures will remain above normal through the period.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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With high pressure settling in behind Tuesday`s cold front and northerly flow developing, dry and seasonable weather is expected Tuesday night through Thursday. By Thursday evening, the GFS and ECMWF begin to show diverging forecasts, with one model showing low pressure over Lake Huron by Saturday morning and the other model showing low pressure across Tennessee. Have stuck close to the Superblend through this part of the forecast.
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&& .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR conditions are expected under shortwave ridging through part of Sunday for most ports, though moist SE upslope flow could result in MVFR ceilings overnight through Sunday for DUJ and possibly FKL. E winds should veer to the SE as a weak surface boundary/warm front moves N across the area. Low pressure is progged to track across the OH valley/lower Great Lakes region Sunday, with increasing shower chances and condition deterioration to MVFR from W-E during the afternoon and evening with it`s approach. A thunderstorm is possible especially for ZZV though low chances and limited instability preclude a TAF mention. Outlook... Restrictions are expected to continue Sunday night with the crossing low. Restrictions are likely again Mon night/Tue with a crossing cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ Update...Kramar

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