019
FXUS61 KPBZ 261130
AFDPBZ

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

.SYNOPSIS...
Strong to severe thunderstorms are expected this afternoon and
evening ahead of a cold front. Isolated flooding is also
possible with heavy rainfall. Temperatures will trend upwards
into the weekend.

&&

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

- Strong to severe storms are expected between 1pm to 8pm.
  Damaging winds will be the main threat. An isolated tornadoes
  and hail as large as a quarter can`t be ruled out.
- Storm Prediction Center (SPC) has expanded the Slight Risk for
  severe weather across the region, and Weather Prediction
  Center (WPC) has continued the Marginal risk for flooding.

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7am Update: The Ohio River Valley is waking up to warm, moist
conditions across the region. Overnight low temperatures ranged
from upper-60s to low-70s. With mostly clear conditions,
diurnal heating will help build instability throughout the day.
GOES-16 and ACARS soundings currently suggest elevated
instability of 500J/kg between 700mb to 400mb at 7am with
effective shear of only 20kts to 25kts. However, progression of
a trough over the Midwest will enhance vertical wind shear from
the southwest across southern Ohio after 15Z.

Previous Discussion:

Pre-frontal showers and thunderstorms will rapidly increase in
coverage to our west early afternoon and track into our region
after 1pm. The primary threat will likely be damaging winds with
lingering dry air aloft producing strong cool downdrafts.
However, hail (dime to quarter in size) and tornadoes can`t be
ruled out. SPC has removed the 2% TOR outlook for the day, but
several machine learning outputs still indicate the potential.

By late evening, the severe threat will likely evolve into a
heavy rain threat, especially for urban areas that experience
training or rainfall rates ranging from 2-4 inches per hour. With
PWATS well above the climatological average (1.65" to 1.90")
and training showers and storms under quasi-zonal flow, swaths
of 1 to 2 inches are not out of the question.

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

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- Dry weather returns.
- Temperatures increase Friday into the weekend.

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Dry conditions resume Thursday as high pressure builds in
across the region. A warming trend in temperatures is
forecasted Friday and into the weekend as h500 heights approach
890dm. This combined with increasing low-level moisture will
result in apparent temperatures back up in the mid 90s by the
weekend.

&&

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

- Shower and thunderstorm chances return Saturday into Sunday
  with the next low pressure system.

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Ensembles show about a 50% chance in general of highs hitting
90F on Saturday. There`s a good chance most locations will see
apparent temperatures back in the 90s with Tds back up in the
upper 60s / low 70s.

Shower and thunderstorm chances return with increased
instability and the approach and passage of another frontal
system Saturday into Sunday.

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

&&

.AVIATION /12Z 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 with a flux of low-level moisture and
diurnal heating.

Pre-frontal showers and storms will increase in coverage from
west to east after 17Z. However, it appears the most favorable
timing for thunderstorms to impact terminals will be between
20Z and 00Z; TEMPO groups have been included with this morning
update. 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;
especially between 06Z to 12Z.

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...Hefferan/88
SHORT TERM...88
LONG TERM...88
AVIATION...WM/Hefferan