034
FXUS61 KPBZ 251046
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
646 AM EDT Tue Jun 25 2024

.SYNOPSIS...
There is a slight chance of showers and storms this afternoon
if the remnants of an upstream convective system hold together and
cross the region, but chances are better that most locations will
remain dry. More widespread showers and storms are expected
Wednesday with the approach and passage of a cold front.

&&

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

- Upstream MCS favored to drop west of the region. This will
  likely leave area dry during the daytime hours.
- Convective cirrus from said convection may inhibit some
  afternoon heating across portions of eastern OH to northwest
  PA.

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WNW flow at 500 mb with 582-585dm heights along with sfc high
pressure now centered east of the region will yield warmer
temperatures and higher Tds as low level moisture increases in
return flow. However, as discussed below, MCS activity is likely
to also notably increase cloud coverage/thickness greater than
model guidance, which may also limit the degree of heating
(currently lowered expected highs for portions of eastern OH
through northwest PA).

Models continue to struggle in handling the evolution of a MCS
currently over eastern Wisconsin. Have maintained slight chances
as forecast confidence is relatively low, but latest obs trends
indicate the MCS beginning to turn more southerly early this
morning which could potentially keep most showers/storms west
of the forecast area later today. Alternatively, if a more ESE
track is maintained, the vast majority of CAMs point towards the
MCS weakening and falling apart as it approaches the region,
keeping the day largely dry.

&&

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

- Showers and thunderstorms are more likely Wednesday with a
  crossing front.
- Severe storms and flooding will be possible.

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A trough and associated cold front cross the region Wednesday,
with a late afternoon/evening FROPA. 25th to 75th percentile QPF
for KPIT ranges from 0.20" to 0.8", and with convection there
will always be a rather large range so this seams reasonable.
Similar to Tuesday, the Wednesday convective setup will be
modulated by the evolution of Tuesdays convective cold pools. In
any case, showers and storms are more likely. SPC is currently
carrying a slight risk as far west as PGH and marginal
elsewhere, with the primary risk being damaging winds. SPC also
shows a 5% and 2% for hail and tornados respectively which lines
up fairly well with the latest 00Z CSU machine-learning
probabilities. WPC has the entire region under a marginal for
flooding.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
KEY MESSAGES:

- Dry weather Thursday through Friday.
- Near normal temperatures Thursday, before a late week warmup.
- Shower and thunderstorm chances return for the weekend.
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In the wake of Wednesday`s front, temperatures return to normal
and dry conditions resume as high pressure builds in across the
region. A warming trend in temperatures is forecast Friday and
into the weekend as heights gradually rise, reaching about
590-592dm by Saturday. 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.

Showers and thunderstorm chances return with the increased
instability and another frontal system Saturday and Sunday.

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

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR is expected through much of the TAF period.

A mesoscale convective system (MCS) was developing across the
Western Great Lakes region. This is initially expected to track
eastward overnight, before diving to the south following the
1000-500mb thickness pattern and theta e gradient. It appears
most of the thunderstorm activity should stay just west of the
area where the best instability is expected, though an increase
in mid and dense high level clouds is expected. There is some
potential the MCS could track further east and reach some Ohio
airports, though a rapid weakening in thunderstorms is expected
by that time. A few SW wind gusts up to 20 mph are expected
today with mixing.

Shower and thunderstorm chances increase late tonight with the
approach of the next shortwave trough and surface cold front.
For now, included a VCSH at the end of the PIT TAF with
uncertainty in how much precip development will occur
overnight.

.Outlook...
Restrictions are expected Wednesday with ocnl showers and
thunderstorms as a cold front crosses the region. VFR returns
Thursday and Friday under high pressure. Restriction, and
shower/thunderstorm potential returns Saturday with the approach
of a cold front.

&&

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

&&

$$

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