Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 230119
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
919 PM EDT Thu Oct 22 2020

.SYNOPSIS...
Unseasonably warm temperatures will continue through Friday. A cold
front provides rain chances mainly Friday night and into Saturday
morning. High pressure will bring drier weather and cooler
temperatures for later Saturday and Sunday.

&&

.NEAR TERM /THROUGH FRIDAY/...
Surface high pressure and that mid-level ridging centered near or
just off of the eastern CONUS coast will keep a mostly clear sky and
well above normal temperatures in place tonight. Surface dewpoints
are 5 to 10 degrees lower than yesterday so will it be harder to
reach saturation in the low levels overnight. With the high
retreating east, the surface pressure gradient will tighten up a bit
and keep the boundary layer a little more mixed. This will likely
lead to some patchy low stratus rather than fog at locations that do
manage to near saturation in the low levels. Overnight lows will
again be mild.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
The Plains trough is still expected to rotate across the Upper
Mississippi Valley Friday morning and the Great Lakes thereafter.
Another warm day can be expected in the continued southerly flow.
A surface low will accompany the shortwave into western Quebec by
Friday evening. Associated frontal passage is still timed for Friday
night. The first rain showers will arrive into eastern Ohio the
preceding afternoon, with PoPs areawide Friday night.

A ribbon of higher moisture, with PWAT values between 1.3 and 1.5
inches, will accompany the front. However, while support for lift
will be provided by right entrance region jet dynamics Friday
evening, the northerly track of the surface low and shortwave will
continue to keep forcing in the low levels limited to the front
itself. The higher PoPs as well as QPF will be found in the western
CWA where the upper dynamics will be strongest. While up to a half-
inch of rain is possible in Ohio, the Laurel Highlands/northern West
Virginia area may miss out again and receive a tenth of an inch or
less. Expect precipitation coverage and intensity to drop off with
time as the front advances, with little more than scattered showers
southeast of Pittsburgh by sunrise on Saturday.

Dry weather returns for Saturday afternoon and night with high
pressure tracking across Michigan and southern Ontario. The quick
push of cold advection will knock temperatures back to levels just
below climatology for Saturday and Saturday night, with any further
drop stunted by a return to southwest flow by Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Dry weather and relatively cool temperatures will continue on Sunday
as the high tracks into New England. Thereafter, a wetter pattern
will develop for the first part of the new work week. A fresh trough
will likely be carved over the Rockies and Plains Sunday and Monday,
with the models now indicated a cutoff upper low developing in or
near Texas by Wednesday. Meanwhile ridging will hang on near the
southeast CONUS coast. In between these features, a warm and moist
southwest flow regime will set up, bringing increased rain chances
into at least Tuesday, and now possibly into Wednesday given the
slower trend due to the cutoff. A frontal passage may then provide
drier weather by Thursday, although details this far out remain
murky.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Widespread VFR will be dominant until end of week with the exception
of any fog around dawn.

.Outlook...

Widespread restrictions will be possible with a late Friday/early
Saturday cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$



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