536
FXUS61 KPBZ 060120
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
920 PM EDT Thu Jun 5 2025

.SYNOPSIS...
A cold front will slowly move eastward into the Upper Ohio
Valley and stall through Friday. Rounds of showers and
thunderstorms are expected through the weekend, as waves of low
pressure track along the boundary. The main threats to monitor
are instances of damaging wind gusts today and Friday, and
instances of locally heavy rainfall creating flash flooding.

&&

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

- Decreasing coverage and intensity of showers/thunderstorms
  overnight
---------------------------------------------------------------

Outside of weak convergence along the higher terrain where
storms are continuing to develop (but sitting generally just
east of the forecast area), the loss of diurnal heating and exit
of an MCV has resulted in a downward trend in shower and
thunderstorm activity. However, subtle waves within the quasi-
zonal westerly flow may still allow for isolated
showers/thunderstorms to occur overnight with the warm/moist
environment in place.

Abundant cloud cover should aide overnight temperature to end up
around 5 degrees above the daily average though localized spots
seeing nocturnal rain could see additional cooling. The clouds
also should limit morning fog generation (favored areas would be
locations receiving higher rainfall amounts) despite a nearly
saturated boundary layer.

&&

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

- Showers and thunderstorms continue at times
- Marginal Risk for damaging thunderstorm wind gusts Friday
- Locally heavy rainfall possible through Friday night
----------------------------------------------------------------

The front will linger across the region on Friday as it remains
fairly parallel to westerly flow aloft. Surface-based CAPE once
again increases into the 1000-1500 J/kg range, fueling an
increase in shower and thunderstorm activity during the
afternoon and early evening. Another round of strong to severe
thunderstorms is possible, with isolated damaging wind once
again being the main threat, although DCAPE may be less
favorable. Another round of locally heavy rainfall/isolated
flash flooding is expected as well, as storms potentially train
near the stalled boundary, as PWAT continues to linger in the
1.5 to 1.6 inch range. Marginal Risks for severe thunderstorms
and flash flooding were maintained by SPC and WPC, respectively.

A vort max/shortwave trough crossing Friday night into early
Saturday morning should result in another round of showers and
thunderstorms crossing the region. A flooding potential could
continue with this activity, especially in areas that become
saturated with rainfall through Friday. The wave should push the
front further south with a locally heavy rain potential. This
wave should drive the front further south later on
Saturday,reducing rain chances during the day, especially north
of Pittsburgh. Another shortwave and surface low are expected
to develop and track east along the front Saturday night,
returning the front northward as a warm front. This should
maintain a chance of showers across the region overnight.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:

- Unsettled weather Sunday through Tuesday
- Dry Wednesday
-------------------------------------------------------------------

Models have trended toward a stronger shortwave trough crossing
the Upper Ohio Valley region on Sunday, as a surface low tracks
along the quasi stationary front to our south. The GFS is an
outlier, developing a stronger surface low and pulling the front
back farther northward than most other guidance. Stayed close to
the ensemble solution, resulting in increasing shower and
thunderstorm chances through the day with the passing wave.

Another trough is progged to tack from the Upper Midwest to the
Great Lakes and Upper Ohio Valley region Monday and Tuesday.
Shower and thunderstorm chances will again increase with the
approach and passage of the trough.

Dry weather is expected to return on Wednesday as the trough
exits, and surface high pressure builds in. Temperatures are
expected to average near seasonable levels through the period.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Much of the widespread convective activity for this evening has
ceased already with things turning over to a more stratiform rain.
This rain can still be heavy in pockets and bring reduced VIS. There
still can be rumbles of thunder over the next couple of hours but
those are expected to be winding down shortly. Isolated to scattered
showers can continue overnight for portions of the area. It is
possible to see the appearance of fog overnight with lingering
moisture and previous rain.

Restrictions return near 12z across the region with a lowering cloud
deck quickly dropping to MVFR then IFR in spots, especially north.
This looks to coincide with a return of more widespread showers near
sunrise before activity can become spottier again near midday with
a gradual improvement in CIGs.

Tomorrow afternoon once again brings the possibility of widespread
shower and thunderstorm activity. At this time this has been
included in the TAFs as PROB30 groups trying to pin down the best
timing for tomorrow afternoon.

Outlook... Widespread MVFR/IFR ceiling restrictions are expected
Saturday as a series of shortwaves brings continued shower and
thunderstorm chances.

&&

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

&&

$$

SYNOPSIS...CL
NEAR TERM...Frazier
SHORT TERM...CL
LONG TERM...CL
AVIATION...AK