-- Discussion containing changed information from previous version are highlighted. --
070
FXUS61 KPBZ 010600
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
200 AM EDT Wed May 1 2024

.SYNOPSIS...
The remainder of the work week will be dry and warm. A slight
cool down is expected this weekend with returning rain
potential.

&&

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

- Clouds will decrease through the night, with areas of fog possible
after midnight.
- Low temperatures several degrees above normal.

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Showers have almost completely departed the forecast area to the
east as a shortwave trough approaches the ridges, with an
accompanying cold frontal passage. The 00Z PBZ sounding shows a
cap in the 750-700mb layer that effectively prevented
convection from getting tall enough to reach the -10C level for
lightning generation.

Weak surface ridging will build into the region overnight, providing
subsidence which will erode most of the remaining cloud cover. With
drier dewpoints slow to arrive from the west, overnight low
temperatures will remain several degrees above climatology. The
lingering moisture, along with light wind, will raise the
possibility of patchy fog after midnight, particularly to the east
of Pittsburgh, where a bit more rain fell today.

&&

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

- Dry weather and above-normal temperatures expected Wednesday.

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Height rises and a return to southwest flow is expected on
Wednesday as temperatures push back into the 80s for most
locations. Clear skies and mixing into day air has led to a
slight upward adjustment in temperatures and downward
nudge in dew points. Nonetheless, fire weather concerns remain
low with light winds and humidity just above thresholds.

A weak front may move in later in the day into eastern Ohio,
but any convection will struggle in dry air. Dry conditions are
favored to continue. Dew points may recover slightly ahead of
the passage.

&&

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

- Warm and dry weather expected under high pressure on Thursday.
- An unsettled pattern returns Friday through the weekend with
  above-average temperatures and periods of showers and
  thunderstorms favored.

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High pressure will continue to support above-normal temps and
dry conditions through Thursday night. Ensemble guidance
indicates the best chance for Thursday afternoon highs to exceed
80 degrees occurs south of I-80 where widespread probabilities
are 70% or greater. Lower probabilities (<50%) exist along and
north of I-80, where temperatures are more likely to top out in
the upper 70s. Lows Thursday night similarly range from upper
50s south of I-80 to low 50s farther north.

Ensembles continue to favor upper level trough movement through
the Great Lakes region Friday into the weekend that would push
the ridge axis southeast and lead to a return of more active
weather. While this more active pattern certainly increases
chances for showers and thunderstorms, it also introduces
greater uncertainty and makes it more difficult to narrow down
details regarding exact timing and intensity. According to the
latest ensemble runs, Saturday appears to be the most likely day
for widespread rainfall, though chances really begin to ramp up
Friday afternoon and could linger straight through the weekend
and into next week. Stay tuned for more on this as we get closer
to the weekend.

As for temperatures, at this time Friday appears to be the
warmest day of the period with highs potentially reaching the
mid to upper 80s across much of the area. In fact, ensembles
already indicate a 70% or greater chance of areas south of I-80
exceeding 85 degrees. Temperatures Saturday through Monday also
trend above normal, but could remain in the 70s due to thicker
cloud cover and a greater coverage of showers and thunderstorms.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
Building high pressure has resulted in light and variable to
calm wind overnight with just a few passing cirrus, but will
also allow for fog development with visibility restrictions to
IFR/LIFR possible for MGW & LBE. Hi-res model ensemble guidance
suggests moderate to high confidence (60-80%) MVFR VIS at these
sites after 07z with the highest probability for IFR coming at
MGW (~60%); probabilities for LIFR VIS at MGW creep up to
30-40%, so have included a TEMPO group to account for this as
confidence is on the lower end in restrictions dipping below
IFR. AGC/PIT have a low (<30%) chance of seeing VIS restrictions
to MVFR but with little to no precip observed in the area and
higher dew point depressions, have left mention out.

VFR quickly returns after 13z Wednesday with high confidence as
mixing commences and ridging builds further. A passing warm
front will bring a modest increase in mid level clouds come late
morning/early afternoon, but otherwise will see southwest wind
prevail around 5-10 knots. Cirrus thicken late Wednesday night
with increasing upper level moisture.

.Outlook...
VFR conditions are expected to continue into Thursday under high
pressure. The next chance for restrictions comes late Friday
into early Saturday with passing low pressure.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...CL
SHORT TERM...Milcarek
LONG TERM...Cermak
AVIATION...Hefferan/MLB