539
FXUS61 KPBZ 051511
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1111 AM EDT Thu Jun 5 2025

.SYNOPSIS...
Shower and thunderstorm chances return today with an approaching
cold front. This front will drift across the region through
Sunday, as waves of low pressure track along it. This will
result in periodic shower and thunderstorm chances through the
weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:

- Shower and thunderstorm chances increase today
- Marginal Risk for mainly damaging wind gusts
- Locally heavy rain possible
---------------------------------------------------------------

The surface front currently lies across northern Ohio to just
along the Lake Erie shoreline and into western New York. Southward
progression remains slow, but an approaching shortwave in
southwest flow aloft will give the boundary a southward push
into our region during the mid to late afternoon. Mid and upper
clouds continue to slowly stream into the region, with cumulus
development expected by early afternoon.

The 12Z sounding showed a cap just above 750mb, but some modest
cold advection at that level should help mitigate this
inhibition. Initial activity should focus closer to the frontal
boundary during the early afternoon before scattered showers and
storms develop further east with time as cold pool interactions
become more likely and as convective temperatures are breached.

Overall shear levels in the 0-6km layer will remain at 20 knots
or less, limiting storm organization, although values could be
a bit higher north of I-80 and perhaps could support a modest
hail threat there. However, the main severe threat is still
expected to be isolated/scattered damaging wind gusts. Although
lapse rates aloft will not be overly steep, DCAPE of 700-900
J/kg should support a downburst threat with any storms that
generate stronger updrafts.

Localized heavy rainfall/flash flooding remains a concern as
well. With precipitable water increasing into the 1.5 to 1.6
inch range, along with slow storm motion and potential for
training along the front, localized heavy rainfall totals of 1
to 2 inches could be realized, perhaps higher on a highly
localized basis.

Another warm day in the 80s is expected before the
shower/storms increase later today.

&&

.SHORT TERM /6 PM THIS EVENING 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 is expected to stall across the Upper Ohio Valley
region tonight. Ongoing showers and thunderstorms should quickly
lose intensity during the early evening, with the severe
thunderstorm threat ending. Elevated instability is progged to
remain overnight, with scattered showers and isolated
thunderstorms still possible.

The quasi stationary front will remain across the area on
Friday, under westerly flow aloft. With building diurnal
instability, expect an increase in coverage of showers and
thunderstorms again through the day. Increasing flow aloft and
MU CAPE from 1000-1500 j/kg could result in a marginal potential
for damaging wind gusts again Friday afternoon and early
evening (as highlighted in the SPC day 2 outlook.) A locally
heavy rainfall potential will also continue with the quasi
stationary front across the area. Will continue to highlight
this and the severe storm potential in the Hazardous Weather
Outlook.

Models indicate a vort max in broad upper troughing will track
across the region Friday night into early Saturday. This should
result in another round of showers and thunderstorms crossing
the region, with a locally heavy rain potential. This wave
should drive the front further south later on Saturday, with
some decrease in rain chances especially north of PIT. 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 WEDNESDAY/...
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 /15Z THURSDAY THROUGH MONDAY/...
General VFR conditions are expected through the TAF period, with
the exception of localized restrictions with afternoon/evening
convection. Mid/upper level clouds will increase through the
morning hours.

Isolated to scattered showers and thunderstorms are possible
later this afternoon and early evening, with the greatest
coverage mainly north of KPIT. Guidance leans towards lower
coverage than previously anticipated, and quickly- dissipating
storms as they cross western PA. There is low confidence on the
continuation of showers after 00z. Generally have kept
prevailing SHRA where confidence in showers/storms is highest,
and Prob30s covering the most likely window of potential
thunderstorms at each terminal. Showers and storms look to
remain fairly high-based, so any restrictions will likely be
limited to brief visibility reductions. Fog may develop into the
overnight near terminals that do see rainfall.

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

&&

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

&&

$$

SYNOPSIS...WM
NEAR TERM...WM/CL
SHORT TERM...WM
LONG TERM...WM
AVIATION...88