Area Forecast Discussion
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FXUS61 KPBZ 281613
Area Forecast Discussion
National Weather Service Pittsburgh PA
1213 PM EDT Wed Sep 28 2016
Upper level low pressure will bring rain to our region for the
latter half of the week.
.NEAR TERM /THROUGH TONIGHT/...
Early afternoon update featured tweaks to POPs and temperature
based on the latest radar, obs, and high res trends.
Upper low pressure will continue to dig over the Midwest during
the near term. Convective temperature will thus be falling and
shower chances increasing today. Dry layers within the atmospheric
column will provide initial inhibition.
Overnight temperature will fall below convective thresholds, but
shortwave impulse/occluded front is progged to rotate around the
parent-low and maintain shower chances for the night.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The aforementioned low is forecast to briefly stall over the
Middle Ohio River Valley on Thursday, before lifting northward and
filling once again through the week. The concern for the period is
late Thursday when an Atlantic moisture tap is forecast to stream
across areas generally along and north of the PA turnpike, and
deepen the overall moisture supply in the column.
Currently-progged rain-supporting dynamics are progged for that
period, but are limited given the lack of convergence/mid level
frontogenetical forcing in this mature stage of the low. The
better probability for heavy rain off the immediate eastern
upslope areas should thus be convection based and instability is
Have used general River Forecast Center QPG for todays prog of the
event in conjunction with WPC QPF probability maps. The bottom
line is no flash flood watch until precursor rainfall tonight at
least defines a better threat area in conjunction with moisture
convergence into the occluded frontal zone.
As the Atlantic moisture tap in interrupted by Friday, the sustained
rainfall threat will be alleviated with more scattered convection
providing the rain chances.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The low is forecast to lift northward and fill through the weekend
with dry flow returning and diminishing rain chances for the
region, and supporting seasonably warm temperature.
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
VFR will predominate today, but deterioration can be expected
tonight as rain chances increase under the encroaching upper low.
.OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...
Periodic restrictions can be expected into the weekend as the
upper level low lingers over the region.