Area Forecast Discussion
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FXUS61 KPBZ 240102

Area Forecast Discussion
National Weather Service Pittsburgh PA
902 PM EDT Mon Oct 23 2017

Low pressure will maintain shower chances and cool temperatures
through mid week.


The late eve update featured tweaks to hourly trends of
temperature. Remaining forecast remains on track.

Changes for the early eve update included timing adjustments to
precip based on the advance of rain-focusing boundaries which
the latest High Res runs have captured well. In addition, gust
magnitude was increased in the immediate downslope areas of the
ridges - that potential is not expected to be long-lived as a
quick veer toward the south is anticipated with passage of a
prefrontal trough.

Otherwise, the deep closed low digging over the Great Lakes
will be compromised by encroaching dry air. Rainfall so has
been limited to about a half inch in general. Flood problems are
not anticipated given rapid progression of embedded shower-
cells and the encroachment of that dry slot this evening.


The closed upper low will linger in the Great Lakes region Tue
and Wed, with likelihood of precipitation being moderated by dry
air being wrapped into the upper circulation.

After a showery day on Tue, the system`s dry slot will shift the
brunt of precipitation ewd, and any remaining showers will be
driven by the cold pool aloft as the trough meanders ewd.

There is a non-zero possibility of snow showers in the ridges
Wed night as cold air invades, but precipitation may be ending
by the time the air cools sufficiently for accumulation.

Owing to the presence of the strong trough, temperature will be
seasonal to below average for the time of year, with maxima in
the low-mid 50s common by Wed.


A quasi-zonal flow pattern will take shape Thu and Fri in the
wake of the early-week trough. However, a deep upper trough will
be carved out in the central CONUS by Fri, and a cold front will
surge ewd, approaching the region by Fri evening.

Thu and Fri seem quite likely to be dry as moisture and lift
will be lacking. However, the weekend likely will be wet and
colder than recent days, as the deep trough is slow to depart.


VFR with occasional MVFR conditions in showers should continue
through the evening with approaching low pressure and
associated cold front. MVFR stratocu is progged later tonight
after FROPA, and this should be maintained part of Tue under an
upper trough and cold advection. Stratocu heights should return
to VFR levels by late afternoon with mixing.

A sufficiently tight pressure gradient should maintain gusty
S-SW winds through most of Tuesday.

Upper troughing should maintain periodic restrictions through
early Thursday. Restrictions are likely with a Sat cold front.




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