Area Forecast Discussion
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FXUS61 KPBZ 192150

Area Forecast Discussion
National Weather Service Pittsburgh PA
550 PM EDT Tue Sep 19 2017

Patchy fog overnight followed by a slight chance of isolated
showers and general thunderstorms south and west of Pittsburgh
Wednesday afternoon. Warm and humid conditions will continue
into early next week.


Precipitation associated with a frontal boundary and mid-level
wave to our northwest continues to struggle as it bumps into
high pressure over our region. Any eastward motion of the high
continues to be blocked by Hurricane Jose in the Atlantic. Only
some minor eastward progress of scattered showers and storms is
anticipated through the rest of the afternoon/early evening as
mid-level capping will hold on from Pittsburgh on eastward. Kept
chance PoPs going to the west, with a bit more of a gradient
than earlier. Little to no lightning observed thus far, but
equilibrium levels of 30k feet suggest some is possible. This
initial activity should mostly die off this evening with
boundary layer stabilization.

Overnight, the front continues to struggle to move southeast,
while the mid-level shortwave and upper cold pool begin to slip
to our southwest into the middle Ohio Valley. This may allow
for a few isolated showers overnight in southeast Ohio/parts of
northern West Virginia, where slight chance PoPs were placed. To
the northeast, clouds may be thin enough to allow for patchy
valley fog formation. Crossover temps not yet established, but
think air temperatures will stay above these for the most part,
ruling out more widespread issues.

Above-normal temperatures were maintained overnight, a pattern
which will continue through the balance of the forecast period.


The upper wave continues its trek to our south on Wednesday, and
with another modestly unstable afternoon, scattered showers and
thunderstorms will again be possible, mainly south of
Pittsburgh. Warm mid levels should keep activity suppressed to
the north.

After the wave exits, ridging will become even more firmly
entrenched over the Ohio Valley/Great Lakes as a deep trough
develops over the northwest U.S. This will lead to dry weather
and further warming through Thursday. Highs in the mid 80s will
become more common.


Little change in the large-scale circulation pattern is expected
during the extended period, with the western trough/eastern
ridge setup maintaining, if not strengthening, through early
next week. As a result, a dry and quite warm forecast continues.
With 850mb temps soaring to the 17-19C range, most locations
outside of the ridges will soar well into the 80s. Cannot rule
out eventually needing a 90 degree reading or two in the warmer
locations. Continued to run with warmer temperatures than
suggested by SuperBlend/MEX.


VFR conditions with diurnal CU and increasing mid/high clouds
are expected into the overnight hours as a weak upper trough
approaches. Clouds should limit fog potential again tonight/Wed
morning., but will go with some restrictions at AGC/FKL/DUJ
where less cloud cover could allow for some fog development.

Other than local morning fog, no widespread restrictions
expected through Sun with building ridging.




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