Area Forecast Discussion
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FXUS61 KPBZ 271836
Area Forecast Discussion
National Weather Service Pittsburgh PA
236 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 TONIGHT/...
Partial decoupling and a dry airmass should result in decent
radiation tonight, so no major alterations were needed to already
seasonably cool lows.
.SHORT TERM /WEDNESDAY 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 /18Z TUESDAY THROUGH SUNDAY/...
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.