-- Discussion containing changed information from previous version are highlighted. --
552
FXUS61 KPBZ 270657
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
257 AM EDT Mon May 27 2024

.SYNOPSIS...
-- Changed Discussion --
An additional round of showers and storms will cross the Upper
Ohio Valley through early morning, with spotty showers and a
thunderstorm or 2 possible again during the afternoon as a cold
front crosses the region. A few cooler days are anticipated
thru mid- week as low pressure aloft becomes stronger in the
eastern part of the country.
-- End Changed Discussion --

&&

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

- An additional round of showers/storms will cross the region
  through dawn.
- Another round of potentially strong to severe thunderstorms
  this afternoon.
-------------------------------------------------------------------

The near term will feature a decaying line of showers and
thunderstorms moving through OH through the early morning hours.
Meso analysis highlights still weak areas of mixed layer CAPE
only topping between 100 and 400 J/kg moving into the area as
the line advances. Despite the tapped environment, some weak
showers continue to develop with and ahead of the main line but
weaken and dissipate. Expect the line of showers and storms to
continue to progress east. The RAP does begin to show an area of
MU CAPE develop into SE OH and into the base of the panhandle
which could lead to an uptick in convection as the line further
traverses through the forecast area. It is worth noting that the
HRRR does show good consistency of an uptick in development and
this is an area that has been hit with repeated rounds of
rainfall leading to a lower FFG. Thus, flash flooding will still
be possible heading through the morning hours.

Heading into the day, the main line is expected to exit the
area by 14Z. Behind this, the cold front is expected to approach
the area between the 20Z and 00Z mark with afternoon heating
and forcing from the boundary may lead to additional
development. The SPC has left the Marginal risk for severe and
excessive rainfall for today. Aided by daytime heating and slow
passage of the cold front, this round of strong to severe
thunderstorms. That said, along and ahead of the cold front,
we`ll likely see additional convection across eastern OH and
western PA, but destabilization remains in question owing to
breaks of cloud coverage as southwest flow aloft advects in
moisture ahead of the front. Large spreads in NBM low end vs.
high end coverage lend lower confidence to this aspect of the
forecast. Mean CAPE is progged around 1000 J/kg and effective
shear near 30 knots, so some strong to severe storms are
possible with primary threats of damaging wind and hail, but
trends will need to be monitored. Highs today will be cooler
than those over the weekend with mid 70s most likely but
dependent on the cloud cover.
-- End Changed Discussion --

&&

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

- Daily rain chances and below normal temperatures take over
-------------------------------------------------------------------

The convection developing with the passing cold front will
finally weaken and dissipate by 00Z to 03Z or advect off into
the northern area of CTP`s forecast area. That should saturate
the area as well for overnight tonight with a weak frontal
passage and light winds with some clearing possible. This will
set the stage for possible fog development.

The upper low will swing more shortwaves around its base and aid in
daily, diurnally driven scattered precipitation chances as well as
below normal temperatures. Late Tuesday into Wednesday morning may
feature the highest rain chances as a more potent shortwave and
surface trough cross the region with 24 hour totals ranging from a
trace to 0.75" at most.
-- End Changed Discussion --

&&

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

- Cool temperatures continue through the end of the week
- Dry weather favored to take over by Thursday
-------------------------------------------------------------------

By Thursday, ensemble disagreement increases with the axis and
strength of the upper trough, but any flavor of solutions doesn`t
kick it out of the eastern CONUS until toward next weekend. Broad
surface high pressure should build on Thursday and turn the area
dry, but it`s possible that it`s slower to build and shower chances
continue into Thursday especially as a potent upper wave makes one
final pass through the area before upper ridging finally builds with
decent confidence among the long range ensembles. Lows may dip as
cool as the low to mid 40s come mid to late week as the cooler
airmass settles in with highs 5-8 degrees below average.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
An additional round of showers/storms will advance west to east
across all terminals from 07Z-12Z with moderate confidence, but
should pose no concern beyond moderate rain and reduced
vsby/cigs.

Most of Mon will remain MVFR-VFR at all terminals until a cold
front crosses the region in the afternoon. Sufficient heating of
the boundary layer may occur to yield modest buoyancy as the
cold front crosses, helping invigorate a cu field and scattered
showers after 18Z. Confidence is highest in convection east of
PIT, so have included PROB30s in for DUJ/LBE/MGE. Elsewhere,
timing and placement of showers is too unclear to include more
than VCSH at the moment. These should clear by early evening.
Gusty wind to 20-25 kts will slowly diminish overnight.

.Outlook...
Periodic restrictions and rain chances continue through mid-
week as a series of disturbances move through the region within
broad ern-CONUS low pressure aloft.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...Shallenberger
SHORT TERM...MLB/Shallenberger
LONG TERM...MLB
AVIATION...Kramar/Rackley