Area Forecast Discussion
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000 FXUS61 KPBZ 272213 AAA AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 613 PM EDT Tue Sep 27 2016 .SYNOPSIS... An encroaching upper low will return rain to the Upper Ohio Region for the latter half of the week. && .NEAR TERM /THROUGH WEDNESDAY/...
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For the evening update, no major changes to previous forecast. Minor adjustments to overnight cloud cover and an update to temperatures using a blend of hires guidance.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... 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. && .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 /22Z TUESDAY THROUGH SUNDAY/...
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VFR conditions will be maintained through the TAf period, with the exception of eastern ports which will see an increase in low clouds tomorrow afternoon as a low level easterly flow pulls moisture over the ridges. Elsewhere, mid cloud cover will be on the increase as a deep upper low drops south over the region. The best chance for precipitation tomorrow at TAF sites will be in the west and east during the afternoon. Showers should hold off until after dark elsewhere. .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. && $$

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