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003
FXUS61 KPBZ 240455 AAB
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1255 AM EDT Fri May 24 2024

.SYNOPSIS...
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Isolated showers or storms are possible south of Pittsburgh
today. The risk for more widespread activity returns Saturday
afternoon. Sunday may be dry as high pressure moves across the
Mid-Atlantic region.
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&&

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

-Lingering showers from a passing shortwave may last through
 late morning Friday south of Pittsburgh, PA.
-Probability of showers and storms decrease Friday afternoon.

_____________________________________________________________

For the overnight period...made adjustments to PoPs focusing on
current conditions and the latest hires model guidance. A
quasi-stationary front has setup shop over the region, pretty
much cutting the forecast area in half. Showers and storms
continue to fire over portions of eastern Ohio along the
boundary. As they move eastward into more stable air, the
activity diminishes. Latest hires model data is indicating that
scattered/isolated activity will continue to develop along the
front overnight. A shortwave will cross the Mid-Atlantic region
late tonight. The front will move very little until this wave
exits.

A Mid-Atlantic shortwave will move south and east this morning.
With the wave moving further away from the region, the stalled
front will then be able to sink further south, perhaps as far
south as central WV. Shower or storm development is still
possible along the boundary this morning, but this risk will
also drift southward and by afternoon any additional convection
would likely be confined to the mountains of northern WV.

The exiting shortwave will allow for height rises over the
region this afternoon. High pressure at the surface will slide
eastward underneath the ridge. This will mean plenty of
sunshine and above normal temperatures.
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.SHORT TERM /TONIGHT THROUGH SUNDAY/...
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KEY MESSAGES:

-A crossing shortwave will return the risk for showers and
 storms Saturday.
 _____________________________________________________________

Ridging will break down across the Ohio River Valley early
Saturday as an ejecting low out of the northern Dakotas tracks
into the Great Lakes. With a flux of low-lvl moisture Saturday
morning, our environment has the potential to support storm
development Saturday afternoon as a weak shortwave trough swings
through. Some models are suggesting a lack of a trigger despite
a decent environment. So confidence is still low on how much
development will occur and how strong it will become.

Another weak ridge will cross the region on Sunday. This should
keep most of the area dry. Popup storms cannot be completely
ruled out Sunday, but most of this may be confined to the higher
elevations.
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.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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KEY MESSAGES:

- Variability remains high on long term forecast and may be
  predicated on prior day`s convective outcomes.
- Overall, periodic showers and thunderstorms with slightly
  above normal temperature is favored through the holiday
  weekend and into next week.
  ____________________________________________________________

A strong, well-organized low pressure system is becoming the
favored pattern towards the end of holiday weekend in the Ohio
River Valley. Timing and the position of the center of the low,
along with environmental moisture profiles, are currently not
in phase between the long range models and some of the newer
runs of the CAMs. There is a very large difference between
800J/kg (GFS) to 3000J/kg (NAM). At the moment, the Storm
Prediction Center (SPC) has focused the convection outlook
southwest of our county warning area.

Long range suggests a shift to a cooler, dry pattern by the
middle of next week as upper troughing develops over the Great
Lakes. Expect temperature to fall below the seasonal average,
with Tuesday potentially being the transition day from shower
activity to dry weather.
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&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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General VFR and light winds are expected under the influence of
high pressure through the TAF period. The chance for an isolated
thunderstorm is rapidly diminishing overnight. The threat for
widespread fog overnight is unlikely as cirrus limits
radiational cooling potential. However, areas that saw afternoon
thunderstorms and remain south of the boundary draped E/W
across the area (i.e. MGW, LBE, ZZV) have a heightened chance
for restrictions overnight.

.Outlook...
Shower and thunderstorm chances return Saturday afternoon and
evening, but may be dependent on evolution of storms that occur
across the western Great Lakes. Any thunderstorm poses a risk
for gusty, erratic winds and lowered visibilities.

Thunderstorm probabilities are highest late Sunday into Monday
as a more robust low pressure system moves through the Great
Lake region. A pattern shift thereafter will introduce periodic
precipitation chances and potential for more prolonged cig
restrictions.
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&&

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

&&

$$

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