265
FXUS61 KPBZ 012308
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
708 PM EDT Tue Apr 1 2025

.SYNOPSIS...
Rain and thunderstorms return tomorrow afternoon with a warm
front followed by a cold front Wednesday night. Multiple days of
rain could lead to flooding late this week; Flood Watch issued
in eastern Ohio.

&&

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

- Dry under high pressure
- Near-normal temperatures expected overnight and early
  Wednesday

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Dry conditions will persist overnight as a high-pressure ridge
propagates eastward. An increase in mid- and high-level
cloudiness is expected, attributed to the advection of
convective outflow from the westward approaching low pressure
system currently entering the Great Plains.

Minimum temperatures overnight will remain near climatological
average, with a notable warm advection event between midnight
to 3am with strong southerly flow between 925mb to 850mb.

&&

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

- Showers and thunderstorms return Wednesday with a warm front
- Waves of showers and thunderstorms continue Wednesday night
  through Friday
- Flood Watch for portions of Ohio
- Locally heavy rainfall possible
- Severe storms possible Wednesday and Thursday

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Strong surface low pressure is expected to track across the
Plains and Upper Midwest region on Wednesday, as a warm front
extending east of the low lifts across the Upper Ohio Valley
region. A vorticity maximum in SW flow aloft will cross the
region at the same time, supporting a wave of showers and
thunderstorms across the area. Instability will be elevated,
with a strong inversion progged above the surface. With strong
shear also in place, the potential exists for hail in any storms
during the day Wednesday. MUCAPE values are progged at around
500 j/kg as the shortwave crosses. The storm potential should
end later in the afternoon as the initial wave exits. In
addition, downsloping SE wind should result in wind gusts from
30-40mph just west of the Laurel Highland ridges Wednesday. Wind
direction and inversion heights currently look less than optimal
for higher gusts.

Mainly dry weather is expected the first part of Wednesday night
with subsidence behind the initial wave. Showers and
thunderstorms will increase overnight as a cold front and
shortwave trough approach. Significant shear is progged to be in
place as the front approaches, with elevated instability. The
potential for severe storms will increase late as the front
approaches, though the available instability could be a limiting
factor.

The forward progress of the front is expected to slow on
Thursday as the front becomes parallel to the flow aloft.
Uncertainty in the exact position of the front exists, which
will impact areas where heavy rain falls, and which areas have
the potential for severe storms. The strongest upper support for
ascent exits the region later Thursday night into Friday, with a
temporary decrease in the heavy rain/storm potential. The front
is also progged to drift just south of the region during the
day, resulting in decreasing POPs.

&&

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

- Showers/thunderstorms increase Friday night and Saturday
- Potential for heavy rainfall
- Colder next week

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A surface low is expected to track NE out of the Mississippi
Valley region Friday night, returning the front northward.
Showers and thunderstorms will again increase in coverage as the
front and surface low move across the Upper Ohio Valley region
through Saturday. The severe weather potential is expected to be
limited with the amount of instability in place, though the
locally heavy rain potential will increase.

The low is expected to move NE of the area on Sunday, pulling a
cold front across the region. The passage of the front will
bring the heavy rain and storm potential to an end later in the
day. An upper trough is then expected to persist across the NE
CONUS early in the week, resulting in cooler temperatures and
rain/snow shower chances.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
High confidence VFR through 14z Wednesday under the influence of
high pressure SE of the region. An approaching upper level
trough from the west will increase area cirrus and slowly
introduce lower mid level decks. Tightening of the surface
gradient between 13z-18z Wednesday will favor 20-30kt ESE wind
gusts through the end of the TAF period, with potential
(20-30%) for 35-40kt gusts at downslope terminal locations
(LBE/DUJ).

Passage of a warm front between 17z-23z Wednesday is expected to
generate a line of showers and embedded thunderstorms, with
moisture convergence aiding mainly MVFR cig generation.
Confidence is fairly high on the timing, with any thunderstorm
duration likely limited to 2 hours.

Outlook...
VFR will maintain with gusty southerly wind Wednesday night into
Thursday morning within the warm sector of the approaching
surface low. Showers and thunderstorms will cross the region
Thursday morning into the early afternoon ahead of an advancing
cold front.

An active weather pattern is favored thereafter as the front
stalls near the region and multiple upper level waves overrun
the Ohio Valley region. Expect multiple periods of heavier rain
and fairly widespread restrictions through the weekend.

&&

.HYDROLOGY...
The potential for heavy rainfall will exist beginning Wednesday
night, and continuing into Sunday. At this time, areas across
Ohio have the potential to see the heaviest rainfall, where a
Flood Watch has been issued. Current NBM values indicate a 60
percent chance or greater of at least 2 inches of rain over a 72
hr period in this region, with lesser probabilities further east.
The exact location of heavy rain will depend on the position of a
quasi stationary surface front. Precipitable water is expected to
remain elevated through Sunday, with some periodic jet enhanced
ascent. Even after the heavy rain potential ends, river levels
will likely remain elevated for a few days. Current ensemble river
forecast projections also focus the most significant river rises
across Ohio.

Will monitor further trends for any future adjustments to the
watch.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...Flood Watch from Wednesday evening through Sunday morning for
     OHZ039-040-048-049-057>059-068-069.
WV...None.

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...WM
LONG TERM...WM
AVIATION...Frazier
HYDROLOGY...WM