661
FXUS61 KPBZ 020519
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
119 AM EDT Tue Sep 2 2025

.SYNOPSIS...
Widespread rain chances return Thursday with the
approach and passage of a cold front. Gusty winds and isolated
storms are also possible with the passage of the front. Cooler
and relatively drier weather returns late week.

&&

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

- Patchy river valley fog is possible
- Isolated showers activity near the ridges this afternoon
---------------------------------------------------------------

GOES-19 Nighttime Microphysics imagery depicts broken mid-level
clouds over portions of the region early this morning. Areas
with prolong clearing, patchy river valley fog could develop
between 4am and 6am.

After sunrise, river valley fog will dissipate with surface
heating/mixing. Isolated, terrain-driven showers are possible in
the Laurel Highlands this afternoon (between 1pm and 5pm) with
shallow instability. This is considered a low chance of
occurrence (10-15%). Otherwise, mostly dry conditions across the
region.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/...
KEY MESSAGES:


- Isolated showers possible south of I-70 Wednesday afternoon

----------------------------------------------------------------

The upper low will begin to lift out of the area and into the
Canadian maritimes Tuesday night while surface wind becomes a
bit more southerly. This will aid in better moisture return on
Wednesday, increasing humidity a bit and boosting afternoon
highs a few degrees above average. A weak shortwave will cross
the region by Wednesday afternoon, but will likely arrive before
better moisture from the south. NBM PoPs show slight chances
for rain Wednesday afternoon from ZZV to MGW, but any showers
are likely to remain isolated as deeper moisture remains much
farther south across the Tennessee Valley.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
KEY MESSAGES:

- Showers, thunderstorms, and gusty winds are expected with a
  cold front passage on Thursday
- Cooler and generally dry weather returns in the weekend
-------------------------------------------------------------------

Better moisture arrives Wednesday night into Thursday with
increasing southerly flow. This should allow increasing cloud
cover and shower chances by early Thursday morning. Cloud cover
and rain chance will keep low temperatures near normal for the
first time in a while.

Better chances of more widespread rain will return Thursday
morning/afternoon ahead of the cold front. Some variability
remains with the strength of the trough, stronger likely
yielding more plentiful rainfall, and weaker keeping most totals
below 0.5". With strong forcing, quick frontal movement, and
deep mixing below a 50kt 500mb jet, gusty winds of 30-40 mph
will be possible Thursday afternoon ahead of and along the
front. NCAR ML convective forecasts low-end severe potential
along the front, but generally keep better chances east of our
area. Any severe threat will need to be monitored, especially as
we come within CAM ranges.

Friday, the closed low may wobble around with some solutions
placing the low over Ontario, and other along the southern shore
of the Hudson Bay. Again, a more southerly and/or stronger
position would mean cooler temperatures, generally more clouds
(or even showers) chances on shortwave spokes, and generally
gustier winds. A more northern and weaker track would mean the
opposite. This keeps next weekends temperature spread anywhere
from the upper 60s to mid 70s for highs, daytime wind spread
anywhere from 25mph to 35mph maximum gusts, and rain chances
anywhere from 0% to 30%.

Most ensembles see a warming trend back to near normal
temperatures as we head into the middle of next week, with only
the exact timing of the warmup the main axis of uncertainty
depending on the departure of the eastern trough.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
High pressure centered over New England will result in mostly
dry weather and light easterly wind through the TAF period.
Lingering moisture between 6-10kft combined with diurnal cu
development favors periods of scattered to briefly broken VFR
cigs in that height range.

Hi-resolution modeling suggests that the combination of heating
and easterly upslope flow may be enough to foster a Tuesday
afternoon shower east of KPIT (20-40%). Any convection is likely
to be very isolated and tend to stay east of the forecast
region/Laurel Highlands.


.OUTLOOK....
High confidence in VFR conditions through Wednesday, though an
approaching upper trough may aid enough moisture advection to
generate an isolated afternoon shower south of KPIT.

An upper level trough and surface cold front is highly likely to
produce widespread rain with low-probability thunderstorms
starting early Thursday morning before tapering off early
Friday morning. Early model analysis suggests a 40-60 percent
probability for MVFR or lower cigs associated with the rain
Thursday, with conditions potentially improving west to east
shortly after frontal passage.

Additional shortwave movement may offer additional rain and
restrictions chances late Friday into Saturday before dry
weather develops to start the next week.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...Rackley/Milcarek
LONG TERM...Rackley/Milcarek
AVIATION...Frazier