473
FXUS61 KPBZ 141353
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
953 AM EDT Tue May 14 2024

.SYNOPSIS...
Showers and a few thunderstorms will be possible today and Wednesday
and again Friday through the weekend as multiple disturbances
cross the region. Temperatures will remain slightly above normal.

&&

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

- Shower/thunderstorm chances return today.
- No severe threat.
  ______________________________________________________________

Made some adjustments to PoPs and wind in the near-term grids,
but the thinking for today overall has not changed. Weak
vorticity advection, mainly through the midday hours, will
continue to support scattered light rain showers. Coverage may
drop off a bit during the afternoon hours in weakening lift and
even some weak subsidence between waves. Instability/shear
parameters are still unimpressive with regards to severe
potential, but a thunderstorm or two remains possible.

&&

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

- Shower/thunderstorm chances continue through Wednesday.
______________________________________________________________

As the mentioned upper trough over the Midwest tracks eastward
across the Ohio Valley into Wednesday and eventually sliding
east of the area by Wednesday night, increasing moisture and
ascent will result in a greater coverage of showers and
thunderstorms across the entire area through that time, with
activity tapering off Wednesday night as an upper ridge begins
to build in from the west in the wake of the trough. Rainfall
amounts are expected to remain generally light through this
system, with widespread amounts forecast to remain in the
0.25-0.75 inch range. Ensemble probabilities of storm total QPF
greater than 0.5" is roughly 60-70% south of I-70 and 40-50%
farther north. In fact, probabilities for an inch of rain in
this 48 hour window are near or less than 30% everywhere. That
said, while widespread rainfall amounts will be generally light,
locally higher amounts will remain possible if any locations
see multiple rounds of thunderstorms during this period, since
the heaviest rates can be expected in any storms. The severe
weather threat remains low as both instability and bulk shear
will be marginal at best during this period.

&&

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

- Dry conditions briefly return Thursday.
- Ensemble spread is still relatively high, but another trough
  appears to bring showers and thunderstorms back to the
  forecast late Thursday through the end of the week.
- Above normal temperatures continue.
  ______________________________________________________________

A weak upper ridge quickly builds into the area in the wake of
the departing trough, bringing a brief period of dry weather
early on Thursday. However, another upstream trough will be hot
on its heels, digging into the Great Lakes region and quickly
ushering the upper ridge off to the east. This will bring
increasing chances for showers and storms back to the area
Thursday afternoon through the end of the week.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
Cigs will lower to low VFR/isolated MVFR this morning as a
shortwave trough, embedded in SW flow ahead of a parent trough
across the Midwest, approaches and crosses the region producing
scattered showers. The showers should become more isolated this
afternoon as the initial wave exits to the northeast.

Removed the prob30 for thunderstorms for most airports this
afternoon. The latest CAMs show very little instability and
forcing available this afternoon. This is supported by the
latest upstream mesoanalysis.

Low VFR cigs and scattered showers are expected tonight as the
next wave rotates around the main trough. DUJ should see cigs
drop to IFR this evening, in a moist easterly flow.

.Outlook...
Restrictions are likely, along with showers and possible
thunderstorms, Wednesday as slow moving low pressure crosses
the region. A brief return to VFR is possible Thursday as
ridging briefly builds in. Restrictions and showers return
Friday and Saturday with another slow moving low pressure
system.

&&

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

&&

$$

SYNOPSIS...88
NEAR TERM...CL/88
SHORT TERM...Cermak/Hefferan/88
LONG TERM...Cermak/Hefferan/88
AVIATION...WM