Area Forecast Discussion
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FXUS61 KPBZ 272213 AAA
Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
613 PM EDT Tue Sep 27 2016
An encroaching upper low will return rain to the Upper Ohio Region
for the latter half of the week.
.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --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.
-- End Changed Discussion --
.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/...
-- Changed Discussion --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.
-- End Changed Discussion --