358
FXUS61 KPBZ 140238 AAA
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1038 PM EDT Wed Aug 13 2025

.SYNOPSIS...
Scattered showers and thunderstorms are expected tonight as a
cold front crosses the region. The front will slowly exit on
Thursday. Mainly dry weather is then expected Thursday night
through Saturday as high pressure builds in.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
KEY MESSAGES:

- Showers and thunderstorms this evening
- Locally heavy downpours possible
---------------------------------------------------------------

Update...
Water vapor imagery shows a shortwave moving across wrn PA with
scattered showers and thunderstorms. Some of these storms have
resulted in locally heavy rainfall amounts. The 00Z PIT sounding
showed a PWAT of 1.88 inches. Will continue to monitor this
over the next couple of hours until convection begins to weaken
with waning instability.

Previous discussion...
PWAT remains high, and buoyancy on the weaker side, suggesting
potential for localized heavy rain with any vigorous updrafts,
but storm movement also is non-trivial, which means heavy rain
ought not to linger from any one storm. However, storm
interactions within the increasing coverage area still will
support localized flash flooding despite the storm movement.
With little predictability in where such interactions might
occur, and the overall limited potential, no flash flood watch
appears necessary at this time. The threat has been highlighted
in the HWO and will otherwise be handled with mesoscale
messaging.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- A few lingering showers/storm Thursday south of I-80
- Generally dry Thursday night through Friday night
----------------------------------------------------------------

The overnight trough axis will influence the region residually
Thu morning, potentially maintaining showers after sunrise. But
a high-confidence upper-level pattern is evident as shortwave
ridging builds into the NE`rn CONUS and the sern ridge develops
NW`ward into the MS valley. The net result during Thu-Fri will
be increasing influence of high pressure and limited risk of
storms.

If any storms do develop, they are most likely to occur within
terrain-induced convergence axes in the ridge zones of WV/PA
during the typical convective diurnal cycle.

With a transitioning pattern and generally clear overnight sky,
heat is not expected to be excessive, with maxima/minima near
normal in the upper 80s/low-mid 60s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
KEY MESSAGES:

- Dry and hot for areas outside of the ridges Saturday
- Shower and thunderstorm chances return Sunday
- Mainly dry and hot Monday
- Showers and thunderstorm possible Tuesday and Wednesday
-------------------------------------------------------------------

A relatively high-predictability pattern is anticipated for the
weekend, as an upper-level ridge builds nwd into the Midwest
while a strong low pressure center remains situated over far nrn
Canada. Between the two extrema, a shortwave trough is expected
to advance across Ontario, with variance in its intensity/poleward
positioning driving uncertainty.

On Sat, this axis is wholly predicted to avoid influencing the
Upper Ohio Valley, with any storm potential tied to terrain-
induced convergence lines in the ridge areas.

On Sun, if the trough axis position develops farther south as
some ensemble members suggest, there may be sufficient ascent on
Sun to support broader storm coverage, especially in the I-80
corridor, where enhanced convergence could exist along a frontal
zone.

Either way, above-average heat (near or above 90F) will return
for the weekend with high confidence. Given potential for higher
PWAT but also greater uncertainty in the degree of dry air
aloft during the weekend, it is unclear at this time whether a
notable risk for flash flooding or severe storms exists. These
concerns will be monitored as confidence in the atmospheric
ingredients increases closer to the weekend.

The broad pattern remains higher-confidence thru early next
week, with a ridge in the wrn CONUS and a trough over ern
Canada. The devil is in the details, though, as there also
remains considerable variance in cluster analysis of the pattern
amplitude and strength.

The net result of this variance suggests that the associated sfc
high pressure to the north of the Ohio Valley has considerable
east/west positioning difference among the ensemble membership,
and therefore makes wind direction/speed prediction difficult,
especially Mon/Tue. Any shower/storm chances during this time
again likely would be tied to terrain-induced convergence lines
along the ridges.

By Wed, the possible approach of another frontal zone into a
warm/moist airmass could support storms.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Current storms are developed off an outflow boundary along the cold
front. They will remain scattered in nature with each each storm
capable of bringing localized reductions in CIGs/VIS as well as
gusty winds. The scattered nature of these storms has been captured
in PROB30s this evening. Confidence in occurrence remains far higher
than location at this time and thus PROB30s have been held and
TEMPOs have not been used.

Once the boundary has passed through and the convection has eased,
ceilings should become widespread VFR with higher confidence for a
short period of time. MVFR or IFR ceilings look likely overnight
with fog possible at a number of ports. At this time TEMPOs for fog
have been included in FKL/DUJ/MGW. If needed we can expand these in
future updates. Degraded CIGs are expected to begin to scatter by
late tomorrow morning.

Tomorrow, VFR ceilings expected during the afternoon with winds out
of the north. Conditions are expected to remain dry for most of the
region. Northern West Virginia may see an isolated
shower/thunderstorm. By tomorrow evening, dry conditions are
expected region-wide.

Outlook... Dry weather expected to prevail into the weekend with
high confidence in prevailing VFR with high pressure developing near
New England.

&&

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

&&

$$

SYNOPSIS...Kramar/WM
NEAR TERM...Kramar/WM
SHORT TERM...Kramar
LONG TERM...Kramar
AVIATION...Lupo/AK