820
FXUS61 KPBZ 042334
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
734 PM EDT Tue Jun 4 2024

.SYNOPSIS...
More widespread thunderstorms return Wednesday into Thursday
with periodic shower chances thereafter into next week.
Temperatures remain above average through much of the week, with
a cooling trend expected into the weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
KEY MESSAGES:

- Dry first half of the overnight with scattered shower chances
  then increasing from the west.
- Mild low temperatures.
--------------------------------------------------------------

Showers and storms have mostly dissipated this evening, though
the remnant outflow boundary continues its trek to the northwest
and has spawned a few rogue showers along it. Any of that will
diminish after sunset and give way to a mostly quiet, warm, and
muggy night with lows only in the mid 60s resultant of
increasing cloud coverage and weak warm advection in gradient
induced southerly flow.

The eastern ridge will flatten and be forced eastward overnight
as the upper trough deepens and an initial shortwave crosses the
Ohio Valley. With waning upper support as the wave flattens out
and diminished instability, CAMs continue to indicate the first
wave of thunderstorms rapidly decaying this evening across
central Ohio, with the remnant light showers crossing into our
area during the predawn hours. More organized convection is not
expected until later Wednesday.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
KEY MESSAGES:

- Showers and thunderstorms are expected Wednesday into Thursday
  with a crossing cold front.
- Stronger storms may produce damaging wind, but the better
  threat remains west of the area.

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

A more vigorous shortwave will rotate around the base of the
upper low on Wednesday as a cold front crosses the Ohio Valley
and eventually crosses our area Wednesday night. Showers and
thunderstorms are expected to develop ahead of this front in the
warm sector. Temperatures in the lower 80s and dewpoints
approaching 70 will increase sfc-based instability to near 1500
J/kg. Modest deep-layer shear increasing to around 40-50 kts
during the evening may support as isolated severe weather
threat, with damaging wind as the primary hazard. An isolated
weak tornado cannot be ruled out, though that threat will mainly
remain farther west. However, early rounds of rain and overcast
conditions, along with waning instability after dark, may act
to hamper this threat. The latest Day 2 Outlook from SPC
includes a Marginal Risk for much of the forecast area,
with a 5% wind threat and 2% tornado threat.

Lingering showers will end pre-dawn Thursday morning as the cold
front crosses. A secondary front is expected to cross later in
the day on Thursday. This will likely return showers and storms
Thursday afternoon/evening.

Warm temperatures are expected again on Wednesday, with cooler,
but still just above-average highs expected Thursday.

&&

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


- Periodic showers with cooler conditions are expected into the
  weekend with a slowly crossing upper-level low.

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

An upper-level low will dig across the Great Lakes Friday and
into New England by Saturday. This will keep cooler and showery
conditions in the forecast as we head into the weekend and into
early next week. While there is low confidence on pinpointing
the best timing of these showers each day, ensembles do agree on
the general showery pattern with upper troughing persisting
through the weekend and possibly into early next week.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are expected to be maintained through the night
and the early morning hours as mid-level ridging begins to
depart the region. Some leftover showers from current convection
to the southwest may approach late tonight or around sunrise
Wednesday, but with much of this activity expected to weaken
with the loss of heating, confidence is low. Did include an
earlier VCSH mention at ZZV/HLG for any stubborn remnants, and
will amend if chances of precipitation increase. Clouds and
overnight mixing should keep fog development at bay.

The main show is still forecast to be during the afternoon and
evening hours, as an approaching shortwave trough allows for the
development of more widespread showers and thunderstorms. Ahead
of this, light wind will pick up out of the southwest and start
gusting to around 20 knots. Do have VCTS mention at all TAF
sites during the afternoon, but timing remains a bit uncertain.
Main impacts from any storms will be downpours leading to brief
IFR/LIFR visibility, gusty and variable wind to perhaps 40
knots, and cloud-to-ground lightning.

.Outlook...
Periodic restrictions are then possible through Saturday as a
slow moving upper low drifts across the Great Lakes region.

&&

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

&&

$$

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