-- Discussion containing changed information from previous version are highlighted. --
679
FXUS61 KPBZ 120655
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
255 AM EDT Sun May 12 2024

.SYNOPSIS...
-- Changed Discussion --
High pressure will move into the area today with lingering
showers ending this morning and sunshine increasing this
afternoon. Southerly flow will bring dry and much warmer
conditions on Monday with temperatures warming about 10 degrees
above normal. Low pressure moving up the Ohio Valley Tuesday and
Wednesday will bring showers and thunderstorms.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
KEY MESSAGES:

- Showers ending today
- Clearing trend later today and tonight
-------------------------------------------------------------------

The latest upper air analysis shows a vertically stacked low
across the Lower Great Lakes region. Scattered showers continue
to rotate around the low. The latest SREF and HREF model output
indicate the low will begin to weaken this morning, as it tracks
eastward toward the East Coast. Scattered showers are expected
to taper off through the morning as the low shifts eastward, and
a ridge of high pressure begins to build in.

A clearing trend has already started across portions of Ohio and
WV, where dry advection has occurred. This clearing trend
should continue from W-E today, though the additional heating
will produce scattered to broken cumulus clouds as low
convective temperatures are in place. Mainly clear skies are
expected by this evening as the ridge builds across the region.
Warm advection aloft should result in a few mid level clouds
increasing, especially later tonight.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
-- Changed Discussion --
KEY MESSAGES:

- Dry weather likely with lower humidity
- Sunshine will bring temperatures close to 80F
-------------------------------------------------------------------

An upper low is expected to move slowly across Kansas and into
Missouri during the period. Downstream short wave ridging will
build 500 mb heights into the lower 5700s and promote sunshine.
850 mb temperatures will warm into the 12-14C range, with
temperatures likely to be up around 80F in the southern half of
forecast area. Continued to bump NBM first guess up 2F as
sunshine and deep mixing to 7,000 feet in the boundary layer
suggest it will have the usual cold bias for MaxT.

There is a low probability of showers north of I-80 in warm
advection regime but this is more likely north of forecast area.
-- End Changed Discussion --

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
KEY MESSAGES:

- Midweek showers and thunderstorms likely, with limited severe
  and flooding threats.
- Dry conditions likely on Thursday
- Ensemble spread is high Friday and Saturday, but another
  trough appears to bring shower chances
-------------------------------------------------------------------

Upper trough expected to move across southern IL Tuesday and
then along IN/KY border Tuesday night. This feature then
progresses across southern Ohio and northern West Virginia
Wednesday and Wednesday night.

Warm and moist advection will push precipitable water values up
around 1.35" by Tuesday afternoon and support showers and
thunderstorms. Lingering showers on Wednesday in weak
deformation zone northeast of the upper low are expected to keep
the wet weather going a second day.

NBM 48 hour Probabilities of exceeding 1" of rainfall range
from about 30% in the northwest portion of the forecast area to
about 50% over the ridges. However, 2" probabilities are less
than 10% and in many cases less than 5%. Instability will be
marginal and 500 mb flow quickly drops below 20 knots Tuesday,
so it appears that the probability of significant impacts for
convection are low.

Upper ridging appears likely for Thursday along with sunshine
and temperatures 75-80F.

Another trough with potential for showers and thunderstorms
appears to be on tap for Friday and Saturday, though
considerable standard deviation is noted in that period over the
Great Lakes area for the ensembles/NBM.
-- End Changed Discussion --

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
VFR conditions are expected to start for most airports. The
exception will be FKL and DUJ, where IFR cigs are expected with
low level moisture in place. Conditions should deteriorate to
MVFR for BVI-AGC-LBE and points north as an upper low drops
southeastward across the region through early Sunday morning.
Scattered showers are also expected with the passage of the low.
ZZV and MGW should have already, or will soon clear as drier air
moves in from the west.

Improvement to VFR is expected from west to east through the day
as the low exits, and high pressure builds in. A
cumulus/stratocumulus layer should also dissipate by evening,
with wind diminishing.

.Outlook...
VFR is expected through Monday night under a ridge of high
pressure. Restrictions are likely, along with showers and
possible thunderstorms, Tuesday through early Thursday as slow
moving low pressure crosses the region.

&&

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

&&

$$

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