048
FXUS61 KPBZ 280736
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
336 AM EDT Tue May 28 2024

.SYNOPSIS...
An upper trough will bring rain chances and cooler temperatures
both today and Wednesday. Dry weather returns by Thursday.

&&

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

- Thunderstorms are possible, but expected to remain sub-severe
  for this afternoon.
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Mid-level troughing is expected to impact the northeast CONUS
today. A parent low in place over the the Great Lakes will be
the main weather feature over the area. Shortwaves rotating
around the low will provide chances for showers and a few
thunderstorms for the coming day with coverage increasing
during diurnally- favored portions of the day. This afternoon`s
activity will likely generate less rainfall than what we have
seen given the poor instability and low topped profiles. Still,
expect enough instability with at least some 500 - 700 J/Kg MU
CAPE and rather weak shear in place with 20 to 30 knots in
place. This will set the stage for some thunderstorm development
during the afternoon, but with tops only reaching 400 MB based
on deterministic model profiles, would expect mainly sub severe
storms with a few possibly becoming strong.

High temperatures today are expected to be just a tad below
normal.

&&

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

- Rain chances are in the forecast for Wednesday.

- Temperatures will drop below normal, as much as 10 degrees by
  Wednesday.
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The parent low mentioned in the near term will continue to be
the main driver of weather across the area heading into the day
on Wednesday. This low will further track east into the New
England region as it further pushes a cold front through the
region. Rain chances will be higher with the stronger wave
timed for a Wednesday evening passage, when rain totals of 0.25
to 0.50 inch appear most likely. NBM probabilities of greater
than a quarter inch are in the 50 to 70 percent range over a
good portion of the region on that day. The chance for greater
instability reaching over 1000 J/Kg MU CAPE for Wednesday may
mean a better chance for strong to at least sub severe storms.
Given the better parameters, there may be a marginal severe
storm during the afternoon and poses something to monitor. The
saving grace this day, is that the shear is weaker than on
Tuesday. The loss of heating for Wednesday during the day will
allow convection to wane just after sunset. Given the cooler air
infiltrating behind the front, Wednesday night will feature
temperatures below normal and fog development unlikely.

Behind the cold front, temperatures will trend below normal,
potentially 10 degrees on the cooler side by Wednesday.

&&

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

- Dry weather and cooler temperatures continue into Friday,
  with some warming starting on Saturday.
- Low rain chances return for Sunday and Monday in a more
  uncertain pattern.
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Surface high pressure builds into the area on Thursday, albeit under
a still-present upper trough, with decent agreement on this scenario
according to cluster analysis.  Will continue with a dry forecast
for now, but would not be surprised if a few isolated showers occur
during the day along the ridges before the trough axis works east of
the area. Below-normal temperatures are likely Thursday/Thursday
night, with lows perhaps in the lower and mid 40s.

Thereafter, an upper ridge axis builds into the region with fairly
high confidence, leading to dry weather from Thursday night into
Saturday at least. Temperatures will moderate back to seasonable
levels by Saturday.

Thereafter, spread in the models increases regarding how quickly the
upper ridge moves off/breaks down and how quickly deeper moisture
returns. Will keep the NBM suggestion of low PoPs for Sunday and
Monday with temperature expectations of near to slightly above
seasonal levels. Stout ridging in place as this next disturbance
arrives may lead to a difficult forecast given the subsidence
and drier air in place to start the new week.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Drier westerly flow will promote widespread VFR conditions
through 15z Tuesday, save for near Lake Erie where cold
advection developing an MVFR to low VFR cloud deck (FKL/DUJ).

Diurnal heating may foster a brief MVFR cu deck at all
terminals before afternoon shortwave movement in NW flow
promotes scattered showers and thunderstorms. Showers are likely
at most terminals while lightning is favored from ZZV through
PIT where the combination of best heating and positioning to
upper shortwave occurs.

.Outlook...
Upper trough over the Great Lakes will provide chances for MVFR
to IFR cigs late Tuesday into Wednesday morning (tied to
moistening of boundary layer to create localized stratus/fog).
Pivoting of the upper trough through the region Wednesday will
generate widespread showers (minimal lightning) and a more
robust cig restrictions.

High pressure and drier northerly flow is expected to favor a
prolonged period of VFR Thursday through the weekend.

&&

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

&&

$$

SYNOPSIS...Shallenberger
NEAR TERM...Shallenberger
SHORT TERM...CL/Shallenberger
LONG TERM...CL
AVIATION...Frazier