PBZ issues Area Forecast Discussion (AFD) at Oct 21, 10:39 AM EDT860
FXUS61 KPBZ 211439
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
1039 AM EDT Mon Oct 21 2024
.SYNOPSIS...
High pressure will maintain dry and warm weather through
Wednesday. Isolated rain chances return Wednesday night into
early Thursday north of Pittsburgh. Seasonable temperatures to
above average temperatures expected to end the week with another
chance for rain.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Dry and quiet weather will continue; above average
temperatures expected
-------------------------------------------------------------------
Given the strong ridge axis over the Great Lakes, as a closed
low advances over the Rockies, low-level temperatures will
continue to trend above-average.
On the 12Z PIT sounding, a warm nose of 17.6C was noted at
961mb. With diurnal mixing, at least 76F high temperatures will
be observed; with other environment factors (sun/little to no
wind) nudged the temperatures up to near 80F around PIT and in
eastern Ohio. Looking at the NBM, this is exceeding the 95th
percentile for Max Temps. If temperatures exceed 80F, a few
climate sites may be in jeopardy of tying and/or breaking their
record high temperature.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:
- Dry weather through most of Wednesday
- Warming trend continues through Tuesday
- Iso/Sct shower chances return by Wednesday night
-------------------------------------------------------------------
High pressure will remain centered across the Ohio Valley
through early Tuesday, sliding east by Tuesday afternoon.
Continued warm advection with 850mb temperatures randing from 12
to 14C should result in high temperatures 15 to 20 degrees above
average. Continued to bump MaxTs toward the 90th percentile
given recent performance. The possible limit on this could be
gradually increasing high clouds through the day ahead of a
weakening shortwave trough.
Said shortwave will advance eastward out of the Midwest Tuesday
night, crossing the Upper Ohio Valley region early Wednesday.
Little moisture is expected to be associated with this weakening
trough, and the main impact on the forecast being slightly
cooler high temperatures.
A second, stronger shortwave and its associated surface cold
front, will approach and cross the region late Wednesday and
Wednesday night. While moisture and lift will be more favorable
for a few showers with the second shortwave, both are still less
than optimal for anything more than minimal rainfall amounts and
scattered precip coverage. Ensembles continue a downward trend
in PoP and QPF, and it appears best coverage of showers will
remain north of Pittsburgh.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
KEY MESSAGES:
- More seasonable temperatures return Thursday in the wake of a
cold front
- Large variability in the pattern over the weekend
-------------------------------------------------------------------
The cold front will clear the area Wednesday night, with any
lingering showers likely to end Thursday morning. With dry air
advection, post-frontal showers will likely depend on modest
lake enhancement in northwest flow. Much more seasonable
temperatures are expected in the wake of the front, with breezy
conditions possible especially in the ridges Thursday afternoon.
Large run-to-run variability continues thereafter through the
weekend. Generally, a deepening shortwave trough is expected to
cross the Great Lakes in the Friday to early Saturday timeframe.
This, along with a surface cold front will introduce additional
PoPs into the forecast overnight into Saturday.
Large spread in temperature probabilities into the weekend
leads to lower confidence and a wide range of possibilities for
daily highs. Exact outcomes will depend on timing /amplitude of
East Coast troughing and strength of West Coast ridging. For
now, have kept grids close to the NBM mean.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR with light winds and minimal cloud coverage expected through
the TAF period as high pressure in control across the region.
Weak surface warm advection and enough boundary layer mixing
should keep river valley fog localized with low probability of
reaching area terminals (FKL/HLG) overnight.
.Outlook...
Persistence of VFR favored through a large portion of Wednesday
until a crossing cold front usher in scattered showers and low
probability restrictions (20-30% probability mainly around
FKL/DUJ).
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...WM/Rackley
LONG TERM...Hefferan/Rackley
AVIATION...Frazier/88
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 21, 10:39 AM EDT---------------
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