494
FXUS61 KPBZ 072343
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
743 PM EDT Tue May 7 2024

.SYNOPSIS...
Severe thunderstorms are expected in Ohio tonight with showers
and isolated severe thunderstorms spreading across the rest of
the area late tonight. More showers and thunderstorms are
expected early Thursday. Cooler and unsettled weather is
expected this weekend.

&&

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

- Severe storms are possible later this evening into early
  Wednesday morning.
- Probabilities for severe weather are highest for our CWA
  across east-central Ohio.
- All modes of severe weather (large hail, damaging wind,
  tornadoes, and flooding) are possible with these storms.

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

Update...
IR satellite and radar VIL loops indicate the band of showers
and isolated embedded thunderstorms across the region will
continue to weaken as it tracks eastward early this evening.
Latest mesoanalysis shows flat upper level ridging across the
Upper Ohio Valley region, resulting in the diminishing trend of
the showers.

As mentioned in the previous discussion below, the severe
weather potential will increase later this evening as shear and
instability increases, and a prefrontal trough approaches.

Previous discussion...
Occluded front approaching area will bring a surge of higher
theta-e air into Ohio with strengthening deep moisture
transport. Initial weakening band of thunderstorms in south
central Ohio will advance east late this afternoon and gradually
weaken.

Of more significance will be severe storms developing in
Illinois and Indiana and advancing across Ohio later this
evening. It appears that strong warm advection will keep things
active until after midnight and elevated CAPE values of 500-1000
j/kg with highest values in Ohio. Significant Severe values up
to 30,000 are expected this evening into east central Ohio,
supporting severe thunderstorms including supercells well into
the evening.

The main activity is not expected to move into Ohio portions of
the forecast area until 9 or 10 pm, and then spread into PA and
WV after midnight. Hail appears to be the primary threat, but
damaging winds and tornadoes can`t be ruled out especially over
western half of forecast area given the potent looking soundings
well into the evening hours over Ohio. Overall flash flood
threat is low but locally intense rainfalls are expected.

&&

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

- Brief ridging will allow for dry weather with sunshine on
  Wednesday.
- Additional storms are possible late Wednesday night into early
  Thursday morning, but highest severe probabilities are well
  south of the forecast area.

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

Weak ridging brings quiet weather on Wednesday into Wednesday
night. However another trough with 50 to 70 meter height falls
pushes a low pressure area up Ohio Valley with a surge of warm
advection showers and thunderstorms. While these could be
severe, odds favor the strong instability to be well south of
forecast area.

&&

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

- Ensembles suggest a wet pattern into the weekend.
- Cooler temperatures arrive by late week with highs in the 60s
  this weekend.
-------------------------------------------------------------------

Strong height falls on Friday usher in a cooler pattern with a
long wave trough position in the east. Showers are likely on a
daily basis into the weekend but especially on Saturday as a 100
meter height fall center pushes across Ohio in the afternoon.

Temperatures Friday through Sunday will be 5-10 degrees below
the seasonal normal of about 70 this time of year.

Some moderation of temperatures is likely Monday and Tuesday as
heights rise and flow turns from northwest to more westerly,
though there is a possibility of another trough dropping over
the northeast on Tuesday keeping things a bit cooler than
currently forecast.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are in place at the start of the TAF period. Main
concern is convection that will move through during the late
evening/early overnight period as shear and instability
increases ahead of a prefrontal trough. Have timed the period of
greatest concern using two-hour TEMPO groups through the TAF
sites...02-04Z at ZZV, 04-06Z at FKL/HLG/PIT/AGC/BVI, 05-07Z at
MGW/LBE, and 06-08Z at DUJ. ZZV is under the gun for the
strongest storms, and hit the visibility and wind possibilities
hardest here, with 45 knot gusts possible as well as some hail.
Storms are expected to weaken as they progress into western
PA/northern WV, and thus have slowly decreasing visibility
impact with time. Behind the main line, MVFR ceilings will
linger for several hours. Weak ridging building into the region
will bring VFR countdowns back to the region by late morning on
Wednesday.

.Outlook...
Restrictions with showers and storms are likely early Thursday
through Friday with crossing low pressure.

&&

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

&&

$$

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