-- Discussion containing changed information from previous version are highlighted. --
749
FXUS61 KPBZ 131145
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
745 AM EDT Sun Jul 13 2025

.SYNOPSIS...
A frontal passage on Sunday brings a bit higher risk for severe
storms and isolated flash flooding, with muted heat. Chance of rain
with a post-frontal trough on Monday and relatively dry conditions
on Tuesday. By midweek, heat, flooding and severe weather concerns
return to the region.

&&

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

- Slightly higher flash flooding threat Sunday; marginal severe
  risk to the east of Pittsburgh.
- Temperatures continue to run above seasonal levels.
- Patchy fog development possible Sunday night in areas that see
  rainfall during the day.

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

The upper ridge that previously sat along the eastern seaboard
pushes east over the northern Atlantic on Sunday in response to
longwave troughing setting up to the west over the Great Lakes.
This shift puts the local area under a region of more unsettled
southwest flow, with height falls providing slightly more
synoptic ascent/forcing than the last couple days which actually
saw weak height rises and associated subsidence beneath the east
coast ridge. This translates to higher confidence in scattered
shower and thunderstorm activity across the region today, with
the greatest chances coinciding with peak heating during
afternoon and evening hours. Unlike yesterday when most of the
thunderstorm activity occurred to our west over the lower Ohio
Valley, on Sunday the best environment for convection will be
across western PA and northern WV where the HREF suggests high
probabilities (~90% chance) of at least 1000 J/kg SBCAPE.
Convective-allowing models also suggest an area of roughly
600-800 J/kg DCAPE values across the same areas, which supports
a low-end threat for damaging wind gusts in thunderstorm
downbursts. The Storm Prediction Center has maintained its
Marginal Risk (Level 1 out of 5) for severe weather generally
east of I-79 for this reason.

Additionally, HREF probabilities for PWATs above 1.6" are high
(>70%), which coupled with slow storm motions (<20 kts deep
layer mean flow) will support a localized flood threat in slow-
moving heavy downpours, especially for urban and poor-drainage
areas. The Weather Prediction Center has maintained its Marginal
Risk (level 1 out of 4) for excessive rainfall over most of the
area east of I-77, with a Slight Risk (level 2 out of 4) even
clipping eastern Indiana and Westmoreland counties where
upslope flow could help focus/anchor thunderstorms over the
ridges and lead to locally higher rainfall totals.

Convection will taper after sunset with the loss of daytime
heating, followed by a quieter (but still warm and muggy) Sunday
night period. Patchy fog will be possible in places that see
accumulating rainfall during the day.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Lesser storm/shower chances Monday afternoon, mainly along the
Appalachian ridges.
- Mostly dry and warm Tuesday.
- West Virginia could see some showers on Tuesday.
----------------------------------------------------------------

Tomorrow, a shortwave trough will move through the area with the
axis expected to be east of Pittsburgh by the time of peak heating.
The best chances for scattered showers/storms are along the ridges
as well as southwestern PA and parts of norther WV. There appears to
be a low probability for isolated severe or flooding threat. If the
trough has a slower timing, this could increase these threats in our
area. Temperatures remain in the mid to upper 80s (about 5F above
normal) with a very modest air mass change behind the Sunday front.

Rain chances decrease into Tuesday with the arrival of surface high
pressure. This will likely bring the region light winds with a
slight decline in dew points and mostly clear skies. This should
keep conditions pleasant despite general upper ridging and high
temperatures above normal. Areas in WV are now looking to have a
high probability of some rain due to a low level shortwave trough
over western Virginia.

&&

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

- Heat Wednesday and Thursday
- Rain chances increasing Thursday into the weekend.

-------------------------------------------------------------------
The area of high pressure will begin to gradually move eastward off
the Atlantic coast, allowing the return of warm and moist southwest
flow. This will likely result in Wednesday being the hottest day of
the work-week with overnight lows staying elevated Thursday morning.
Heat Risk tops out at "Major" levels with the most recent update.
There is still about four degrees of temperature uncertainty
Wednesday related to precipitation chances and cloud cover.

Depending on the speed of a trough passage and cloud cover trends,
temperature spread increases Thursday. Thursday has the potential to
be comparable to Wednesday`s heat, although most ensembles have more
cloud coverage and the best chance of rain this week due to a
shortwave skirting south of the main surface front. Wednesday and
Thursday also have the highest proportional chances of severe
weather and flooding as indicated by machine learning, and CIPS
analogs.

Rain chances linger through Friday as the probability for the main
surface front passage increases, though at this point, there are
varying solutions in clustered guidance with some solutions
suggesting ridging in the upper Great Lakes which would maintain
near 588dm heights and warmth, but some show trough development
which might sweep downstream and return temperatures close to normal.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR conditions prevail at all area terminals to start the TAF
period. A few isolated showers east of PIT may impact LBE
briefly with MVFR visibility, otherwise mainly quiet weather
continues through the morning.

A cold front brings higher precipitation chances to the area
Sunday afternoon. The best coverage likely occurs after 18z.
VFR will prevail outside of showers/storms, with brief
restrictions possible in any precipitation. Some storms could
become strong and will be capable of producing damaging wind
gusts and frequent lightning. Convective activity will again
generally follow the summertime diurnal cycle, tapering after
sunset with the loss of daytime heating. MVFR/IFR fog is likely
to develop after midnight at any terminal that receives
rainfall.

Outlook... Scattered diurnal convection now appears more likely
on Monday and Tuesday, potentially leading to brief
restrictions during the afternoon/evening hours. Localized
morning fog also can`t be ruled out. Precipitation and
restrictions become more widespread on Wednesday and Thursday
as southwest flow and moisture increase.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Lupo
NEAR TERM...Cermak/CL
SHORT TERM...CL/Lupo
LONG TERM...Milcarek/Lupo
AVIATION...Cermak/CL