FXUS61 KPBZ 171526
Area Forecast Discussion
National Weather Service Pittsburgh PA
1126 AM EDT Wed Jul 17 2019
The remnants of Barry will produce periods of showers and thunderstorms
today, with locally heavy rain possible this afternoon and evening.
A hot and humid airmass will remain in place through the weekend.
.NEAR TERM /THROUGH TONIGHT/...
Small tweaks to near term PoP and temps to better capture current
radar and sfc ob trends, but the overall forecast message remains the
Widespread showers and thunderstorms are expected through tonight as
the remnant wave of Hurricane Barry shifts from Indiana through the
upper Ohio River Valley and into the northeast U.S. Storms will
become more focused and organized during the late afternoon and
evening hours along a cold front that will drop south out of the
Great Lakes. Slight drier and cooler air plus NW flow behind the
front will end precip chances, with the front moving through the
entire area by Thursday morning.
The warm, humid environment Today will be characterized by marginal
CAPE, weak shear, and notably deep moisture with PWATs 2.5 SD above
normal. Expect fairly efficient rain making processes that will allow
for significant accumulations in short periods of time, making flash
flooding the predominant weather threat for Today. However, given
fairly dry grounds resulting in higher FFG and hi-res models lacking
enough high QPF signatures, will forego a flash flood watch at this
time. A watch may be needed if more training of storms occurs, so
radar trends will need to be monitored.
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
Brief NW flow behind the cold front and exiting Barry remnants
Thursday morning will quickly becoming a building ridge by the
afternoon. Building pressure heights will allow for hotter high
temperature Thursday despite the cold frontal passage, with most
areas above normal. Residual moisture along the eastern ridges into
the WV mountains plus daytime heating may allow for a few afternoon
Increasing heights and moist southerly sfc winds are expected Friday
into Saturday as the 500mb high becomes centered over southern WV,
resulting in hot and humid conditions with little chance for rain
outside of iso storms Saturday afternoon. Confidence is high that
most locations outside of the higher terrain will reach Heat Advisory
criteria (apparent temperature of 100F or higher) both Fri/Sat, with
increasing confidence of Heat Warning criteria (105F or higher) for
southeast OH into portions of extreme western PA. Social Media and
HWO messaging will continue but, given potential impacts with heavy
rains Today, will delay any hazard issuance at this time.
While low, there is a chance of a storm complex moving out of the
Great Lakes and into our northern CWA late Thursday night into
Friday. This rain and its resultant cloud cover could also alter the
heat advisory potential.
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
The ridge will begin to break down Saturday night through Monday as
a series of shortwave troughs roll through the region with periods of
showers and thunderstorms. The trough axis should dig farther south
by Tuesday in conjunction with a sfc cold front, resulting in a
return to drier weather and near normal temperature.
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
Coverage of showers and storms will increase over the course of the
day as deeper moisture and the upper wave associated with the
remnants of Barry arrive. Restrictions are likely...deteriorating to
IFR or lower this evening with a combination of IFR cigs and vis
MVFR/IFR restrictions will continue into Thursday morning.
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