882
FXUS61 KPBZ 260516
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
116 AM EDT Wed Jun 26 2024

.SYNOPSIS...
Mainly dry weather is expected tonight. Strong to severe
thunderstorms will be possible Wednesday afternoon and evening
with a crossing cold front. Isolated flooding is also possible
with heavy rainfall. Temperatures will trend upwards into the
weekend.

&&

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

- Mainly dry conditions are expected overnight, though light
  showers may be possible for some.
- Mild temperatures with increasing humidity overnight.

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

Evening Update...
Convective-allowing models have backed off on the chances for
shower and storms overnight tonight in our area. The PIT 00Z
sounding shows a dry deep-layer profile and with no development
or even percolating occurring upstream, that solution is a bit
more believable right now than the alternative. As such, lowered
PoPs across much of the area at least through Midnight. Some
light shower activity could be possible on the fringes of our
area, primarily north of I-80 and over central/eastern Ohio,
during later overnight hours and into Wednesday morning.
Elsewhere, dry weather is expected tonight but mild temperatures
and increasing humidity as moisture gradually returns from the
west and dense cirrus prevents much radiative cooling.

Previous Discussion...
A mesoscale convection system (MCS) continues to dive south,
within an elongated ridge. Precipitation chances have remained
west of Pittsburgh due weak instability. There was a brief
period of thunder near Coshocton/Muskingum County earlier, along
the edge of the MCS. However the threat has subsided and rain
showers remain.

With increasing cloud coverage from outflow of the MCS and
precipitation chances, temperatures north of I-70 will likely
trend near average. Areas south may trend 5 degrees above
average.

&&

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

- Showers and thunderstorms are likely Wednesday with a new
  disturbance.
- All threats (flooding, tornadoes, hail, and wind) appear
  promising early afternoon through late evening.
- Storm Prediction Center continues to have a Slight Risk for
  portions of our region, Weather Prediction Center continues
  the Marginal risk for flooding.
-------------------------------------------------------------------

An ejecting shortwave out of the Midwest will regenerate showers
and storms Wednesday across the Ohio River Valley. A few storms
may be considered strong to severe if conditions permit,
damaging wind gust and hail will be the main threat. However,
the tornado threat is considered slightly above the
climatological average given directional and vertical wind
shear. Based on Hi-Res model ensembles, the joint probabilities
of bulk wind shear (>= 30kts) and instability (CAPE >= 500J/kg)
are elevated between the period of 1pm to 8pm Wednesday.
However, storms could evolve as early as 10am under a warm,
moist unstable air mass.

The severe threat will likely evolve into a flooding threat as
the day progresses, especially late evening with ongoing
convection. With PWATS well above the climatological average
(1.65" to 1.90") and training showers and storms under zonal
flow, swaths of 1 to 2 inches may occur across the region
Wednesday night. If these noted high amounts occur over urban
areas in a short time period, flash flood products will need to
be issued.

The severe weather and flash flood threat will likely decrease
after midnight as the shortwave tracks east.

&&

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

- Dry, quiet weather is expected Thursday.
- Probability of above average temperatures increase Friday
  into Saturday.
- Shower and thunderstorm chances return Saturday into Sunday
  with a new disturbance.
-------------------------------------------------------------------

In the wake of Wednesday`s shortwave and associated front,
temperatures return to normal and dry conditions resume as high
pressure builds in across the region.

A warming trend in temperatures is forecasted Friday and into
the weekend as heights gradually rise, reaching about 588-590dm
by Saturday. If showers and storms are absent for a prolonged
period of time, apparent temperatures could range from 95F to
100F. However, confidence is still low on heat impacts given
long range ensembles tracking a new trough over the Great Lakes
and could stir strong to severe storms.

Dry conditions and near to slightly above normal temperatures
are forecast early next week as high pressure resumes control.

&&

.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
VFR is expected through the morning ahead of an approaching
shortwave trough and associated surface cold front. Mid and high
level clouds will continue to stream across the area ahead of
the wave. Expect a scattered cumulus layer to develop by late
morning/early afternoon.

Shower and thunderstorm chances will increase by mid afternoon
as the shortwave/cold front approach and cross the region. It
appears the most favorable timing for thunderstorms is between
20Z and 00Z. Included TEMPO groups in the taf sites for the most
favorable timing at any particular airport. Strong wind gusts
and hail are possible in these storms, and additional details
can be added to the tafs as uncertainty decreases later in the
day.

MVFR is expected as the thunderstorms end, with a period of
showers. Eventual IFR is possible overnight with low level
moisture in place.

.Outlook...
Restrictions in stratus/fog are possible through early Thursday.
VFR is then expected through Friday under high pressure.

Restriction and showers/thunderstorm potential returns Friday
night with a crossing warm front. Restrictions are expected at
times Saturday and Saturday night with showers and thunderstorms
ahead of and along a crossing cold front. VFR returns Sunday
under high pressure.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Cermak/Hefferan
SHORT TERM...Hefferan
LONG TERM...Hefferan
AVIATION...WM