624
FXUS61 KPBZ 050513
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
113 AM EDT Sun May 5 2024

.SYNOPSIS...
Intermittent rain and a few afternoon storms are possible
today. Temperatures will moderate as southerly flow returns. A
break in the widespread rain is possible Monday.

&&

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

- Showers continue today.
- Strong afternoon thunderstorms possible with the passage of a
  cold front.
-------------------------------------------------------------------

Overnight period in pretty good shape. Made some adjustments to
PoPs combining radar trends and latest hires model guidance.

A weak shortwave trough will move across the Upper Ohio Valley
today. This wave will weaken and push the east coast ridge out
over the Atlantic. A surface cold front, trailing the upper
wave, will cross the region today, reaching the eastern edge of
the forecast area by early evening. The main moisture plume,
that has been parked over the region for the last couple of
days, will drift eastward with another weak shortwave behind
the exiting ridge. This decrease in deep moisture, and loss of
upper level support, should allow for a brief respite in the
widespread showers. As the aforementioned cold front moves
eastward across Ohio early this afternoon, showers and a few
storms will redevelop and accompany the boundary as it clears
the rest of the forecast area. SPC continues to advertise a
marginal risk for severe storms today. The main driver in this
assessment is the rapid destabilization of the atmosphere ahead
of the front. However, latest model data continues to show a
weak sheared environment, which will work against updraft
enhancement, and plenty of cloud cover that will hinder day
time heating. Additionally, weak warm air advection aloft may
also work to cap the atmosphere. There could be some breaks in
the cloud cover this afternoon with the warm advection, but will
there be enough time to further destabilize the atmosphere?

With the surface flow veering to the south then southwest, and
the warm air advection aloft, temperatures will again rise
above seasonal averages.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
KEY MESSAGES:

- Break in the rain possible Monday for a large portion of the
  region.
- Temperatures remain above normal Monday.

-------------------------------------------------------------------

A shortwave trough will dig into portions of the Upper Midwest
Monday morning. This will promote modest height rises over the
region. Weak cold air advection behind today`s cold front will
spread somewhat drier air over the area. This should allow for a
break in the rain and some decrease in cloud cover Monday
afternoon. A weak shortwave moving eastward around the main
trough, could bring the risk for isolated to scattered showers
over locations mainly south of I-70.

Temperatures will cool a bit on Monday, but still remain above
normal.

Lots of uncertainty on Tuesday that will depend on the path of a
weakening shortwave trough and the crossing of a surface warm
front. If the trough digs further south, rainfall coverage
would be more focused on the southern half of the forecast area
as the surface boundary would not make as much headway to the
north. If the wave shifts further north and the warm front does
as well, then the showers would do the same. Further
complicating Tuesday is the speed of the wave. A faster exit
could cause modest 500mb height rises during the afternoon.
Latest blended guidance is leaning toward a more northerly and
slower track of the wave, so will ride with that solution.

Temperatures will warm once again on Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:

- Rain chances continue through the week but more uncertainty
  lends to lower confidence.
- Temperatures favored to remain above normal.
-------------------------------------------------------------------

An active weather pattern will remain in place for our region,
with decent daily precipitation chances through Friday. Deep-
layer shear will increase as well behind the departing ridge, so
severe weather chances will need to be monitored as well.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
Waves of showers will continue on and off through the morning
as weak shortwaves traverse the upper flow. Meager warm
advection aloft and light southeasterly winds have promoted some
lifting to VFR early this morning, primarily for PIT and areas
south. This may begin to fill in again with MVFR/IFR ceilings
closer to sunrise, but uncertainty remains high.

Height rises and diurnal heating will lift area cigs by 15Z and
will result in a brief lull from convective activity. The
passage of a shortwave and associated weak surface cold front
will then create scattered thunderstorm coverage primarily
after 19Z - lingering into the early overnight.

.Outlook...
A moist boundary layer behind the frontal passage and evening
thunderstorms Sunday night likely will lead to widespread
MVFR/IFR restrictions. Some improvements are expected Monday
with influence of high pressure to the north, but shortwave
movement across the TN River Valley may maintain some
restriction/precipitation chances for southern terminals.

The rest of the week will remain active with varying periods of
precipitation and restrictions amid low pressure passage.

&&

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

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...22
LONG TERM...22/CL
AVIATION...Rackley/Frazier