303
FXUS61 KPBZ 120739
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
339 AM EDT Mon May 12 2025

.SYNOPSIS...
Low pressure is expected to move slowly across Mississippi
today, Kentucky on Tuesday, and Ohio on Wednesday. Increasing
clouds and moisture will lead to showers and thunderstorms
through Wednesday. Another low moving across the Great Lakes
Thursday and Friday will bring more thunderstorm possibilities.

&&

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

- Clouds increasing central and south but sunshine keeps things
  warm I-80 area on north
- Showers moving into the south this afternoon
-------------------------------------------------------------------

Strong trough coming onto West Coast will start to create a more
progressive pattern this week across the CONUS and will give
the closed low in lower Mississippi River Valley the boot.

NW to SE oriented upper ridge is overhead currently, but will
push to the east.  Upper low over Louisiana expected to drift
northeast into Mississippi today, with 40 meter height falls
overspreading forecast area. High clouds have spread across the
central and southern areas, but skies remain clear along I-80
corridor.

Went between NBM Mean and 90th MaxT in the far north, and
lowered Tds to between mean and 10th percentile.

Expect thickening mid to high clouds today with
showers possible in the south by midday and but I-80 corridor to
stay dry with partial sunshine. Temperatures will be warmest in
the north where lower 80s expected, but readings will only peak
out in the middle 70s in the south and then will likely cool
later in the afternoon as precipitation creates some wet
bulbing.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:

- Locally heavy rain possible this afternoon and tonight over
  Preston and Tucker Counties WV and area wide Tuesday
  especially over the ridges
- Showers and thunderstorms linger on Wednesday
----------------------------------------------------------------

Upper low crosses Tennessee tonight and Kentucky on Tuesday
before reaching Ohio on Wednesday. Deep south to southeast flow
is expected during the period with increasing moisture and
precipitable water values in the 1 to 1.5" range. While showers
can occur at any time, expect a typical increase in coverage and
intensity with diurnal heating each afternoon and evening.

WPC has a marginal risk in Preston and Tucker Counties WV
Today, and across the forecast area Tuesday with a slight risk
in eastern Tucker County. NBM 72 hour PQPF 25th percentile is
0.25-0.50" most areas but 0.75-1.00" over the ridges. 75th
percentile ranges from 0.75-1.00" most areas but 1.50-3.00" over
the ridges with highest amounts over eastern Tucker County WV.

&&

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

- Thursday night into Friday has the potential for strong to
  severe thunderstorms
- Temperatures 15-20F above normal especially Thursday/Friday
-------------------------------------------------------------------

Ridge building ahead of strong trough in Upper Mississippi River
Valley will bring warmer day with more sunshine and less shower
threat on Thursday. 850 mb temperatures over lower Ohio Valley
could warm into 20-24C range with +16C over the forecast area,
resulting in middle 80s highs. It appears that the warm sector
will be capped most of the day Thursday upstream, allowing very
unstable conditions with SBCAPE of 2,000-4,000 j/kg to build up
over Indiana and Western Ohio.

Models have been relatively persistent at pushing strong warm
advection across area late Thursday night and Friday morning.
That is when the strongest moisture transport is shown to push
through Upper Ohio River Valley and so round of weakening
thunderstorms that still could be strong to severe is likely.
SPC post-processing GEFS based severe shows highest
probabilities of severe staying west of area on Thursday and
then south and east of area on Friday which appears reasonable.

While deep low moves from Great Lakes to Ontario on Saturday, a
fast moving trough moves beneath it and across the Ohio Valley
bring another chance of showers and thunderstorms to the
forecast area. Heights begin to rise on Sunday as the trough is
likely headed across the northeast and New England and would
expect a drying trend although timing differences in the
ensembles suggest showers are still possible.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
With retreating high pressure, expect mainly clear skies despite
some upper level cloud cover advecting in from the south. Winds
will remain light and variable through dawn. Expect mid and
lower cloud cover to move in through the day with showers
developing after 18Z for the southern terminals and then moving
further north affecting the rest of the terminals by 21Z to 00Z.
Here will be the best chance for MVFR/IFR and below conditions.
As the low inches northward, there will be some low level wind
shear developing in the morning.

The NBM probs give well over 70% probs for MVFR and below cigs
by tomorrow night. Thus, will put these conditions in the TAF
through tomorrow evening with some PROB30s including showers and
reduction in vis to MVFR values. Will see these conditions begin
to worsen after 00Z tonight to IFR and below by the end of the
TAF period for most terminals. The winds will remain light.

Outlook...
Additional shortwave movement within the fairly stagnant upper
low that will sit over the Ohio River Valley will create
periodic shower and isolated thunderstorm chances through
Wednesday favoring the afternoon and evening hours. Area
restrictions may be more closely tied to surface boundary
positioning and prior rainfall, creating more spotty and
fluctuating cig heights.

Drier weather with VFR is likely Thursday under brief shortwave
ridging before the next low pressure system arrives Friday.

&&

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

&&

$$

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