-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 261124
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
724 AM EDT Fri Apr 26 2024

.SYNOPSIS...
Dry and warmer today. The risk for showers returns late tonight
and Saturday. Big warmup expected Sunday and Monday.

&&

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

- Dry and warmer today

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Upper level height rises today as an amplified ridge axis moves
across the Upper Midwest. Surface high pressure will drift
across the New England States this morning. Low-level flow on
the backside the high may push some moisture back over the
region this morning. Seeing some differences in the possible
cloud cover from this moisture. The NBM keeps the highest
probabilities of total cloud cover bottled up on the eastern
side of the ridges, showing around 10% prob for >50% cloud cover
west of the ridges. HREF is more bullish with cloud cover
particularly later this morning and into the afternoon.
Indicating around 60% prob of >50% cloud cover. Will lean toward
the NBM solution as it did a good job with yesterday`s
persistent cloud cover.

Increased warm air advection will nudge highs back above normal
today.

&&

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

- Showers late tonight and Saturday with a warm front
- Warmer Sunday with an isolated shower/storm possible in the
  afternoon

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Upper level ridge axis will slowly move through Ohio tonight and
then across the rest of the forecast area on Saturday. A surface
warm front will trail just behind the axis and push northward
through the region late tonight and Saturday morning. Showers
will accompany the passing boundary. Rainfall looks to be light
with NBM probs of >0.1 inches around 30 to 40% tonight and 20 to
30% Saturday morning. The highest probs are generally over the
I-80 corridor through the period. Showers should end late
Saturday morning or early afternoon as the front will move well
north of the region. Thunderstorm chances appear minimal as
forecast soundings show little to no instability and a strong
low level inversion. Warm air advection is anticipated behind
the boundary, so temperatures will continue to moderate on
Saturday. A limiting factor for highs on Saturday will be cloud
cover behind the front associated with a shortwave trough that
will push the morning ridge east of the area.

Strong height rises return Saturday night and an impressive
ridge will take hold over the region on Sunday. A weak shortwave
will try and sneak over top of the ridge bringing a small
increase in shower/storm chances Sunday afternoon. The area with
the highest probs for measurable precipitation will be north of
Pittsburgh where 30 to 40% probs for >0.01 inches rest. With
such a strong ridge, and forecast soundings showing a cap, it
should be difficult for much activity to develop.

Warm air advection will continue on Sunday and temperatures will
rise into the 80s across much of the district.

&&

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

- Warm with minimal chances of afternoon thunderstorms Monday.
- More widespread showers and possible thunderstorms with a
  Tuesday cold front.
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Model ensembles continue to indicate a strong ridge Monday.
The ridge axis is expected to shift slowly eastward later
in the day, with slightly better chances for afternoon showers
and thunderstorms as a shortwave trough, and associated surface
cold front, begin to approach from the Midwest.

Temperatures mainly in the 80-85 degree range (outside of the
higher terrain) are expected Monday.

Showers are likely, along with a few thunderstorms, on Tuesday
as the trough and cold front cross the region. The precipitation
should end Tuesday night as the front exits.

By Wednesday, one thing is more certain; the ridge amplitude
will decrease. Clustered variability of the 500mb pattern sits
anywhere between a weak 500mb trough to a weak 500mb ridge. This
ridge breakdown may lean towards more unsettled weather.

Late next week, a central CONUS ridge may develop (shown in 3
out of 4 clusters). Should it develop, it is favored to move
east (as shown in 2 out of 3 clusters) and allow warmer-than-
normal temperatures to continue through next weekend. Some
alternate scenarios include 1) the ridge not developing,
whereby temperature would remain closer to normal in zonal flow
and 2) the ridge develops but does not move east and enforces
eastern troughing, which would keep temperatures below normal.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
VFR is expected through this evening as the center of surface
high pressure moves east of the region. Model soundings
indicate scattered diurnal CU developing after 14Z as
convective temperatures are reached. These should dissipate by
evening while mid-level cloud cigs will be increasing ahead of
an approaching warm front. Scattered rain showers and MVFR cigs
are expected toward the tail end of the TAF period.

A better established southeasterly flow sets up today, with
winds around 10 knots gusting to 15-20 knots at times,
particularly at LBE and DUJ where downsloping enhancement may
occur.

.Outlook...
Showers and restrictions are likely on Saturday with the
passage of the warm front. The highest SREF probabilities of
persistent MVFR are currently north of PIT. VFR is then expected
Saturday night through Monday as a ridge builds across the
region, though an isolated afternoon thunderstorm is possible
Sunday mainly north of PIT.

More widespread restrictions in showers and thunderstorms are
expected with a Tuesday cold front.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory until 9 AM EDT this morning for PAZ007-013-014-
     020-022-077-078.
     Freeze Warning until 9 AM EDT this morning for PAZ008-009-015-
     016.
OH...Frost Advisory until 9 AM EDT this morning for OHZ039>041-
     048>050-057>059-068-069.
WV...Frost Advisory until 9 AM EDT this morning for WVZ001.

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...22
LONG TERM...22/Milcarek
AVIATION...Cermak/WM