Area Forecast Discussion
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000 FXUS61 KPBZ 211904 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 304 PM EDT SAT MAY 21 2016 .SYNOPSIS... A wet weekend will give way to a drier beginning to the new week. Warmer conditions will also follow for much of the upcoming week. && .NEAR TERM /THROUGH SUNDAY/... A very slow-moving mid-level system is currently shifting eastward across the upper Ohio Valley. Copious low-level moisture ahead of this system, combined with a surge of mid-level moisture and accompanying drop in mid-level temperatures, have allowed for showers to blossom liberally as the system has pushed into the CWA today. These showers will move eastward through the CWA into the evening and leave a very moist boundary layer in their wake. While flow will slowly edge northwesterly as surface low pressure moves east of the ridges, inversions will likely prohibit substantial vertical mixing such that low stratus and fog will be common overnight into morning even as organized rainfall ends. The break in organized rainfall looks to be fairly short. Another wave is evident on satellite imagery this afternoon north of Lake Superior and set to surge southward overnight. The interaction of this wave with the system currently over the area will basically preclude substantial clearing and also bring a secondary surge of mid-level cold air into the CWA for Sunday. This will allow for more unstable lapse rates yet again. Model soundings do indicate 500-900 J/kg of CAPE and given that the majority of it is in the thermal charge separation layer, a slight chance of thunderstorms was added to the forecast for Sunday. However, Sunday certainly does not look like at all the washout that Saturday has been. Fries && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
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Remaining diurnal rain showers over the east will taper off Sunday night after the atmosphere becomes more stable. The slow moving vertically-stacked low pressure system will linger along the Mid- Atlantic through Monday. Meanwhile, a ridge will continue to build west of the area and will try to suppress cloud and rain production. Enough moisture and instability associated with the low remains over our eastern 1/3 Monday afternoon for showers with isolated thunder. This activity will once again diminish with the setting sun. Tuesday should remain dry as the low slowly meanders up the coast and the ridge crawls in. Sunshine and increasing southwesterly flow will lead to climbing temperatures through midweek. tax
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&& .LONG TERM /WEDNESDAY THROUGH FRIDAY/... Ridging building across the eastern United States will result in southwesterly flow, tapping moisture from the Gulf of Mexico. Compared to previous model runs, Wednesday appears to be mostly dry, but otherwise there should be a fair chance for showers through the rest of the week. Kept thunder mention during afternoon/evening hours following a diurnal cycle. Temperatures will be above normal through the period. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... IFR conditions are still fairly widespread as ample low-level moisture remains behind this morning`s rain. In addition, incoming showers from Ohio will bring CIGs and VISs down yet again. While the surface low is tracking northward through the area, exceedingly weak easterly flow on the northern flank of it is insufficient to allow for stratus to mix out west of the ridges. This has been consistent in the observations at KMGW and KAGC, while KLBE`s 16z report seems a suspicious outlying observation. Regardless, as showers return this afternoon, everywhere should go back down. .OUTLOOK /SUNDAY THROUGH WEDNESDAY/... Restrictions will lift on Sunday with dry weather expected through Wednesday. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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