Area Forecast Discussion
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000 FXUS61 KPBZ 271836 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 236 PM EDT Tue Sep 27 2016 .SYNOPSIS...
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An encroaching upper low will return rain to the Upper Ohio Region for the latter half of the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Partial decoupling and a dry airmass should result in decent radiation tonight, so no major alterations were needed to already seasonably cool lows.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
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The Great Lakes upper low is forecast to dig southward across the Mid, and Upper Ohio Valley for the latter half of the week. As models have come into more consistent depictions, confidence in the forecast of showery weather with reduced low-to-high temperature spread has improved sufficiently to increase POPs to likely and categorical numbers. The better chances for sustained rainfall is over areas north of I 70 where a southeasterly wind will briefly support transport of deeper Atlantic moisture into a frontal zone rotating around the upper low on Thursday. Overdone, to inconsistent omega fields and dry air encroachment into the mid levels of the mature low with inconsistent frontal placement do not lend confidence to placement of a heavy rain axis; thus, QPF was tempered between WPC/RFC solutions over the past couple of forecast runs.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Most of the models lift the stubborn upper low from the middle Ohio Valley at the start of the period into the eastern Great Lakes by 12Z Sunday. Details of individual waves rotating around the low remain tricky at this distance, so kept PoPs fairly general, with a slow decreasing trend through the weekend. Expect Sunday night into the first portion of next week to be dry as a flattening ridge arrives. Near-climatological temperatures will edge back above normal by the end of the period with the departure of the upper low. SuperBlend values were slightly knocked back early in the period, but later numbers looked reasonable. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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Gusty surface winds will lessen early this evening as the night time inversion sets up. VFR conditions will be maintained through the TAf period, however, cloud cover will be on the increase as a deep upper low drops south over the upper ohio valley. The best chances for precipitation tomorrow at TAF sites will be late afternoon through early evening. .OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/... Upper-level low pressure will settle over the region for the rest of the week. Periodic restrictions in showers, with more sustain potential at DUG and FKL should be anticipated.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ 15/88

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