064
FXUS61 KPBZ 072324
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
724 PM EDT Sat Jun 7 2025

.SYNOPSIS...
Unsettled weather is expected Sunday through Tuesday with a
series of crossing disturbances. Strong wind gusts and
localized flooding remain possible in heavier storms.

&&

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

- Dry weather expected through evening.
- Showers and storms return from southwest to northeast
  overnight tonight.

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

Drier weather has settled in this afternoon with partly cloudy
skies and a rain free forecast through this evening. Shower and
thunderstorm chances increase from southwest to northeast
overnight as another shortwave trough digs into the Ohio Valley,
lifting the front back northward into the local area.

Lows tonight remain mild as lingering low-level moisture keeps
dewpoints in the upper 50s to low 60s and increasing cloud cover
limits radiative cooling.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
KEY MESSAGES:

- Marginal Severe Weather and Slight Excessive Rainfall
  Outlooks for Sunday.
- Flood Watch has been issued from 7AM to 10PM on Sunday.
- Marginal Severe and Excessive Rainfall Outlooks for Monday;
  unsettled weather continues through Tuesday.

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

As another shortwave moves into the Ohio Valley tonight, a
surface low begins to develop over OH and pushes northeast
during the day Sunday. This will bring widespread shower and
thunderstorm activity back to the forecast area, including the
potential for additional heavy rainfall during the day as the
low treks east in close proximity to (or directly through) the
local area. Depending on the track of this surface low, there
could be some potential for strong to severe thunderstorms
during afternoon hours. A northerly low over Lake Erie and
western New York would allow a warm front to push north of the
local area, putting us in a warm sector where the latest HREF
suggests high probabilities (>70%) of at least marginal
instability (SBCAPE > 500 J/kg) and deep-layer shear exceeding
40 knots, which would support a damaging wind gust threat and
potentially even a tornado threat. Meanwhile, if the surface low
takes a more southerly track (say, across northern WV), the
front would remain to our south with little to no instability in
the local area and thus a much lower severe threat.

At this time, the most likely scenario appears to have the
surface low tracking almost straight across the local area,
which would leave portions of extreme southwest PA and northern
WV (generally areas southeast of Pittsburgh) in the more
favorable severe storm environment while areas farther north and
west remain less favorable.

The other main threat on Sunday will be rainfall. Right now, the
highest confidence in the potential for heavy rainfall is
generally near and south of the Mason-Dixon line, and even
more so over the ridges of northern WV. Both the NBM and HREF
suggest medium to high probabilities (40-70%) of at least an
inch of additional rainfall in these areas. Meanwhile, farther
north, there is lower confidence as the NBM shows a 20-30%
probability for an inch while the HREF suggests a second local
probability maximum of 30-50% over portions of eastern Ohio to
the west of Pittsburgh. These variances are likely attributed to
differences in the surface low track, but the key takeaway is
that at least a low-end threat for additional heavy rainfall
exists across most of the area. This is especially the case for
areas that have already seen heavy rainfall in recent days,
where soils are more likely to be saturated and runoff more
efficient. A Flood Watch has been issued from 7AM to 10PM on
Sunday.

There will be a trailing cold front draped across the area as
the main low lifts to the northeast Sunday night. This will
serve as a focus for additional convection on Monday. With
ensembles suggesting high probabilities of at least 1000 J/kg
SBCAPE ahead of this front, there will once again be a risk for
strong to severe storms Monday afternoon. Additionally, the
residence time of the boundary will continue to support some
potential for excessive rainfall. Thus, both the Storm
Prediction Center and Weather Prediction Center have highlighted
marginal risks for severe storms and excessive rainfall,
respectively, across most of the local area.

The upper trough finally advances eastward across the Ohio
Valley Tuesday into Tuesday night, pushing the front through
and to the east of the area. More showers and storms will
accompany this passage and, given amount of rain that will have
fallen on prior days, carry a continued threat for excessive
rainfall and localized flooding.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:

- Dry and less humid weather returns Wednesday through Thursday
  night.
-------------------------------------------------------------------

The trough exits during the Wednesday morning period, with high
pressure building into the region. This will result in dry
weather from Wednesday through Thursday night, along with a
slow warming trend. A passing trough will bring a chance of
rainfall back to the area for Friday. Deep-layer flow during
this period will be out of the southwest and thus it will remain
to be seen if the potential leads to any severe or flood risk.

&&

.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
High confidence in VFR through 06z with increasing mid to high
level clouds in advance of the next low pressure system. The
exception is patchy surface haze as a result of wildfire smoke
that is reducing visibilities to 5-6SM; low confidence in
duration of these conditions, with thinking that veering to east
wind will alleviate concern.

Approaching low and its warm front should lift a swath of
showers with low probability embedded thunderstorms northward
between 06z-12z Sunday, reaching NW PA by 17z. Visibility may
initial become MVFR within heavier pockets prior to cig
restrictions, but top-down moistening is likely to foster MVFR
and brief IFR between 12z-18z before seeing some improvements. A
nominal easterly component may provide enough downslope effect
to delay cig restrictions along the Laurel Highlands through the
day (MGW/LBE/AGC).

While there is some uncertainty in precipitation timing and
restriction development, the bigger unknown is tied to how far
north warm front lifts. Sites near/south of I-70 may see the
boundary lift northward enough to allow for brief heating and
fuel thunderstorm potential after 18z. Though probability for
lightning exists through FKL, confidence is lower in this area
that enough instability develops for thunder.

Precipitation is likely to taper off west to east through 06z
Monday, but lingering moisture is likely to promote MVFR/IFR
stratocu overnight.

Outlook...
Diurnal mixing and southwest flow should provide VFR conditions
by Monday afternoon, but an incoming cold front and upper level
wave will increase shower and thunderstorm potential Monday
evening into early Tuesday morning.

Outside of a few scattered rain showers Tuesday, the trend
favors drier conditions and more prolonged VFR periods mid week.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from 7 AM EDT Sunday through Sunday evening for
     PAZ020-021-029-031-073>076.
OH...Flood Watch from 7 AM EDT Sunday through Sunday evening for
     OHZ049-050-058-059-068-069.
WV...Flood Watch from 7 AM EDT Sunday through Sunday evening for
     WVZ001>004-012-021-509>514.

&&

$$

SYNOPSIS...Cermak/Shallenberger
NEAR TERM...Cermak/Shallenberger/Lupo
SHORT TERM...Cermak/Shallenberger
LONG TERM...Cermak/Shallenberger
AVIATION...Frazier