Area Forecast Discussion
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000 FXUS61 KPBZ 181644 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1244 PM EDT Fri Aug 18 2017 .SYNOPSIS... Rain chance will continue through much of the day. The risk will return again Saturday afternoon. Temperatures will stay warm through the weekend. && .NEAR TERM /THROUGH SATURDAY/...
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Cold front bi-secting the area will bring gradual relief in the form of lowered dewpoint temperatures. With the muggy airmass still in place, diurnal cu has developed and hi-res models suggest the development of scattered showers this afternoon. Will keep chance PoPs lagging behind the current precipitation edge along the cold front. Otherwise, gradually improving conditions should exist through tonight. Tonight, some clearing will be realized, but we will remain under the influence of the upper trough. This could work in some additional clouds, but meager moisture will quell any shower chances. Lows will remain just above seasonal average values, but with lower dewpoints invading, it will feel much fresher. Another, fast-moving, shortwave trough will move into the area tomorrow. Bolstered by cooling mid-level temperatures, developing showers and thunderstorms should move quickly through the forecast area. Model soundings show a speed max in the mid- levels, coincident with at least some modest instability. This, and the lowered freezing level to near 10kft should be enough to pose at least a marginal severe threat in the afternoon hours. Will continue to monitor this in the coming updates.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
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A line of showers and storms will be exiting northern West Virginia and the mountains of southwest Pennsylvania and western Maryland early Saturday evening. Dry weather will be invading from the west with differential anti-cyclonic vorticity advection moving in. Benign weather takes hold the balance of the short term. Lowering humidity with dewpoints in the lower 60s will give us a break from the recent run of upper 60s to lower 70s Sunday. H8 temps hover around seasonal norms /14C/ correlating to daytime highs in the upper 70s to lower 80s. Bias corrected all blend was used for temperatures.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/... Broad high pressure will keep conditions dry Monday into Tuesday before another cold front brings a chance of rain back to the forecast for late Tuesday into Wednesday. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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Showers and thunderstorms are dwindling west to east this afternoon, but some re-development could occur along the cold front still in the area. Outside of any brief shower/thunderstorm this afternoon, VFR conditions are expected in altocu. Winds will increase through the afternoon, gusting occasionally to near 20kts. Tonight, clear and nearly calm conditions could produce some valley fog, but this should largely be limited to favorable sheltered locations. Saturday, a fast moving disturbance will bring additional brief restrictions as shower and thunderstorm chances increase in the afternoon hours. Otherwise, VFR conditions are expected. .Outlook... VFR conditions are expected the latter part of the weekend, marred only by pre-dawn valley fog.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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