-- Discussion containing changed information from previous version are highlighted. --
282
FXUS61 KPBZ 271159
AFDPBZ

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

.SYNOPSIS...
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.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
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.

&&

.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 /12Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
With the overnight round of showers and storms exiting the area
to the east, expect brief improvement in conditions in its wake
before MVFR stratocu settle back in this morning. Ceilings will
then improve throughout the day as heating and mixing generally
raises cloud bases to around or above 5kft AGL by the afternoon.
A few showers and thunderstorms will be possible during
afternoon hours with associated local restrictions as well as
low-end potential for damaging straight line winds and large
hail. A weak front pushes through the area around 00Z, briefly
shifting winds to more westerly and ending rain chances across
the area. Mostly VFR then prevails overnight with the exception
of MVFR stratocu persisting north of I-80.

.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.
-- End Changed Discussion --

&&

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

&&

$$

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