949
FXUS61 KPBZ 170831
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
431 AM EDT Tue Jun 17 2025

.SYNOPSIS...
Showers and thunderstorms continue today, and the ongoing flood
threat has expanded to include areas farther north above the
I-80 corridor as a stalled front currently to our south lifts
north across the region. The ongoing active pattern should
break Friday, followed by drier conditions and area temperatures
climbing into the 90s by the end of the weekend.

&&

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

- Flash flood threat spreads areawide, with probabilities
  highest in locations previously impacted by flooding.
- Isolated instances of a damaging wind threat south of I-70.
---------------------------------------------------------------

Latest radar imagery shows showers and a few embedded storms
continuing as anomalously high moisture air continues to lift
over a boundary south of the region in southwesterly flow. There
is still concern that showers with moderate to heavy rain rates
could result in localized flooding this morning, particularly
along a line running roughly from Zanesville, OH to Pittsburgh
or Butler in SW PA, where current upstream convection over south
central Ohio is showing rates up to 3" per hour in some spots.
This will be closely monitored.

The aforementioned pseudo-stationary frontal boundary that has
been parked south of the region the past couple days will
finally push north as a warm front today as the associated
surface low cruises northeast up into Ontario. The overall,
environment will be very similar to the past couple days, but
PWATs will rise with increased moisture in strengthening
southwesterly flow, close to record levels. Storm motion will
slightly quicker than previous days, but in any case the risk of
heavy rain will be high given PWATs near 2", warm cloud depth
~12kft, HREF mean CAPE values up to 1500 J/kg, and many areas
primed for flooding due to previous rainfall. Ensemble guidance
shows good continuity with previous runs, showing a swath of
highest amounts roughly between Pittsburgh and Dubois.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
KEY MESSAGES:

- Showers and thunderstorms continue into Wednesday, with
  increased potential for strong to severe storms.

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

Unsettled southwest flow continues overnight as additional
embedded shortwaves and jet induced ascent support rounds of
showers and isolated thunderstorms, though the focus for
greatest coverage shifts to areas generally south of Pittsburgh.
The flood risk could continue with these into early Wednesday
morning, especially if they impact any locations that have
already experienced flooding issues due to recent rain.

A trough will then advance eastward across the Great Plains and
towards the Great Lakes, resulting in strengthening deep- layer
west- southwesterly flow downstream over the Ohio Valley. Weak
500mb height rises over the local area could provide enough
subsidence aloft to inhibit shower and thunderstorm activity
Wednesday afternoon and evening, with model soundings suggesting
a rather stout capping inversion forming near 700mb. This would
be for the best, as the same soundings also suggest that the
strengthening deep-layer flow, lingering low-level moisture, and
dry air aloft (due to the aforementioned subsidence) would
otherwise support damaging winds (1000+ J/kg DCAPE) and large
hail (2500+ J/kg SBCAPE) in storms.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
KEY MESSAGES:

- Showers and thunderstorms continue Wednesday and Thursday,
  including increasing severe potential.
- Hot and dry weather returns this weekend into next week.
-------------------------------------------------------------------

The upper trough continues to advance eastward across the Great
Lakes Wednesday night into Thursday. As it approaches, height
falls and strengthening large-scale forcing overspread the
region, leading to showers and thunderstorms forming over Ohio
and moving east across the local area. These storms will still
carry a severe weather threat, primarily for damaging winds and
large hail. The Storm Prediction Center currently has much of
the local area in a Marginal Risk (Level 1 out of 5) during that
period. The heavy rain and flooding threat will likewise
continue with these storms, although faster motions will help
limit residence time in any one location and therefore the
threat will become more isolated to areas that already flooded
due to heavy rains in recent days.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
MVFR cigs continue generally along a line from BVI to LBE and
points north. These should continue for much of the night on the
northern side of a low level boundary across the area.
Thunderstorms are possible this evening at ZZV as convection has
fired to the south of this boundary, where clearing and diurnal
instability developed. Otherwise, expect additional showers and
embedded thunderstorms overnight as an upper level wave moves
along the boundary, under a mid level jet. Expect cigs to lower
to MVFR, and patchy IFR, by morning with low level moisture in
place.

The boundary will lift north Tuesday, as additional upper level
lift crosses the area. Expect numerous showers and thunderstorms
by afternoon, with associated vsby and cig restrictions.
Included a tempo mention for thunderstorms for the most likely
time of occurrence. The convection should gradually diminish
Tuesday evening with the loss of daytime heating and diurnal
instability.

Outlook...
Periodic restrictions are expected through Wednesday as another
upper level wave crosses the region. More widespread
showers/thunderstorms are expected late Wednesday into Thursday
with the approach and passage of a cold front. Late night/early
morning stratus and fog is also likely. General VFR is expected
to return Friday as ridging begins to build in.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from 11 AM EDT this morning through this evening
     for PAZ007>009-013>016-020>022-029-031-073>078.
OH...Flood Watch from 11 AM EDT this morning through this evening
     for OHZ039>041-048>050-057>059-068-069.
WV...Flood Watch from 11 AM EDT this morning through this evening
     for WVZ001>004-012-021-509>514.

&&

$$

SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...Cermak/Frazier
AVIATION...WM