085
FXUS61 KPBZ 292345
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
745 PM EDT Fri Aug 29 2025

.SYNOPSIS...
High pressure will provide mostly dry conditions through the
Labor Day weekend, with a slow moderation in temperature back
towards seasonal levels by early next week. The next decent
chance of rain arrives Wednesday into Thursday with an
approaching front.

&&

.NEAR TERM /THROUGH SATURDAY/...
KEY MESSAGES:

- Dry weather and below average temperature through tonight
- Potential for locally dense valley fog overnight
---------------------------------------------------------------

The prior forecast remains on track. Locally dense fog is
possible tonight, with guidance continually hitting on river
valleys.

.. Previous Discussion ..

Clouds will continue to decrease this evening as surface high
pressure tracks southeastward across Michigan. The clearing sky and
decreasing wind will promote radiational cooling. Widespread lows in
the 40s are expected, with some upper 30s possible in sheltered
valleys/normal cold spots. Would not be shocked if the Canaan Valley
NWR mesonet site manages to drop into the 20s. With the rivers
remaining warm, a round of valley/river steam fog appears
likely. HREF visibility probabilities target areas north of
Pittsburgh as having the best potential for locally dense fog
(perhaps under 0.5 mile visibility in spots).

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Dry weather continues, with only an isolated WV ridge shower
  or two possible Sunday
- Temperatures remain below normal but begin to slowly moderate
----------------------------------------------------------------

Any morning fog will lift with the onset of diurnal mixing on
Saturday. Model moisture/CU Rule fields suggest isolated cumulus at
best during peak heating hours, thus the mostly sunny forecast.
Temperatures will trend a touch warmer than Friday, but continued
northerly flow will keep values below seasonal norms. Low
temperatures will similarly moderate slightly, but should still
remain cool enough for another night with some river valley steam
fog.

Ridging over the Upper Midwest on Sunday will help to force a
shortwave trough axis eastward and across our region. Surface high
pressure centered over the eastern Great Lakes will keep the dry
forecast going for most of the region. The lone exception could
be the West Virginia ridges, where models are still showing
inverted surface troughing and weak upslope flow. Isolated
showers are a possibility during the afternoon, with measurable
precipitation chances remaining at 20 percent or less.
Temperatures will moderate a bit, with the easterly flow perhaps
providing warming help via downsloping in some areas. Still,
values will likely remain a touch below normal.

Any ridge showers should end by sunset, and a quiet and seasonably
cool Sunday night is still figured.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Quiet and dry Labor Day and Tuesday with seasonable
- Rain chances return Wednesday/Thursday
- Temperatures cool once again for Thursday and Friday
-------------------------------------------------------------------

Broad upper troughing remains in place for the most part next week.
Some model solutions suggest a 500mb closed low may develop
somewhere over the northeast CONUS on Labor Day and drift off to the
north with time. In any case, surface high pressure extending from
New England to down along the Eastern Seaboard should maintain
mostly dry weather through Tuesday, along with fairly seasonable
temperatures.

The trough should be reinforced during the second half of the week
as models show a shortwave digging into the Upper Midwest on
Wednesday. After this, there is widening disagreement among ensemble
members regarding the disposition of this disturbance, with the
various clusters showing strength and timing differences with the
wave and its impact on the depth and position of the larger-scale
trough. Nevertheless, there does appear to be a signal for
increasing precipitation chances on Wednesday, with a potential peak
on Thursday with a frontal passage. Ensemble/NBM probabilities
suggest a 50-60 percent chance of at least 0.25" of rain areawide
during this period, which would certainly be welcome given our
recent dry pattern. Instability progs and extended machine-learning
guidance suggest quite low severe storm potential for our region,
with better but still fairly low chances mainly east of the
Appalachians. Rain chances may then drop off Friday behind the
departing front.

Temperatures should remain fairly seasonable ahead of the front on
Wednesday, before a likely  to below-normal values for Thursday
and Friday as the trough is reinvigorated.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Regional satellite shows a bit more robust stratus and cirrus
over the area and upstream than previously anticipated. BKN/SCT
ceilings are expected to remain near 5kft with before eventually
scattering from north to south early Saturday morning. Because
of this, have reduced fog mention. Clearing by 9-10z should be
sufficient for some river fog development, with greatest
probability at FKL and MGW.

Lingering cold advection and moisture is likely to result in a
few to scattered 3-6kft cumulus Saturday after 15z. Wind will
remain light and northerly through the period.

.OUTLOOK...
Save daily morning fog chances, VFR is confidently forecast
through the Labor Day weekend with prevailing high pressure.

&&

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

&&

$$

SYNOPSIS...CL
NEAR TERM...CL/Milcarek
SHORT TERM...CL
LONG TERM...CL
AVIATION...Rackley