-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 251741
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
141 PM EDT Thu Apr 25 2024

.SYNOPSIS...
Dry weather is expected through Friday as high pressure moves
across the region. Shower chances return Friday night and
Saturday with a warm front. Other than a slight chance of an
afternoon shower or thunderstorm, mainly dry and much warmer
weather is expected Sunday and Monday.

&&

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

- Dry and warmer today under building high pressure

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

The aforementioned freeze warnings and frost advisories have
been cancelled with temperatures rising above freezing. Today`s
forecast is shaping up to be largely dependent on cloud cover.
In areas where clouds linger, cooler and slightly more saturated
cognitions are favored, while clear areas will trend warmer and
a bit drier. The forecast has been adjusted to reflect this.
Fire weather concerns are minimized with continued cloud cover
and calm winds.

.. Previous Discussion ..

HREF cloud product has been depicting this morning`s stratocu
layer well. The latest satellite imagery and recent model output
indicates partial clearing of the stratocu will continue early
this morning, especially across Ohio and far NW PA. The clearing
should accelerate through the morning as surface high pressure
builds across the Great Lakes and Upper Ohio Valley region,
under a broad upper trough.

Otherwise, dry warmer weather is expected today under the
building high, though highs are still expected to be around 5
degrees below average. Dew points are expected to drop with
mixing this afternoon, though current RH projections are above
30 percent for all but NW PA. Wind is also expected to be light.

&&

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

- Dry and warmer through Friday
- Showers and possible thunderstorms return Friday night into
  Saturday with a warm front

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

High pressure will maintain dry weather tonight. Radiational
cooling should be somewhat limited by warm advection aloft,
despite coupling at the surface. Temperatures should be cold
enough for some patchy frost in some locations north and west of
Pittsburgh, though the patchy coverage precludes an advisory at
this time.

The center of the surface high will shift east of the region on
Friday, as upper ridging builds eastward across much of the
Eastern CONUS. Rising 1000-500 mb heights, and warm advection,
should drive temperatures back to or just above average for this
time of the year.

The upper level ridge axis is expected to move just east of the
region Friday night and Saturday, as warm, moist advection
tracks across the Upper Ohio Valley region in SW flow aloft.
A surface warm front is also expected to lift NE across the
region, with scattered to numerous showers moving across the
region. A rumble of thunder is possible with limited
instability across NW PA and eastern OH. The showers should
taper off from SW-NE through the afternoon as the front lifts
north of the region, and the upper support exits.

Generally dry weather is expected for most of the region
Saturday night as a ridge becomes reestablished across the SE
CONUS, and extends northward to the Upper Ohio Valley region. A
few showers will still be possible across far NW PA as a weak
vorticity max crosses on the northern periphery of the ridge. A
noticeable warming of overnight lows is expected, with readings
around 15 degrees above average by Saturday night.

&&

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

- Warm with minimal chances of afternoon thunderstorms Sunday
  and Monday
- More widespread showers and possible thunderstorms with a
  Tuesday cold front
-------------------------------------------------------------------

Model ensembles continue to indicate the strongest riding across
the Upper Ohio Valley region Sunday and Monday. Sunday should be
mainly dry under the ridge, with warm air aloft limiting
convective potential. Still, an isolated afternoon storm or two
is possible, mainly north of Pittsburgh, where another vort max
moves across southern Ontario on the northern periphery of the
ridge.

Similar conditions are expected Monday. The ridge axis is
expected to shift slowly eastward later Monday, with slightly
better chances for afternoon showers and thunderstorms late in
the day as a shortwave trough and associated surface cold front
begin to approach from the Midwest.

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.

Greater uncertainty exists on Wednesday, with differences in the
strength and timing of a trough approaching from the Upper
Midwest. Stayed close to the ensemble blend, resulting in shower
and possible thunderstorm chances returning through the day.

Temperatures mainly in the 80-85 degree range (outside of the
higher terrain) are expected Sunday and Monday with a 1000-500
mb height of 582 dm, and 850 mb temperatures ranging from 12-14
deg C. Cooler, but still above average, temperatures should
return Tuesday behind the front.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
Stratocumulus continues across a significant portion of the
forecast area early this afternoon while ceilings have generally
lifted to low-end VFR (3-5kft). Some erosion is beginning to
take place along the southern border of this cloud deck per
latest visible satellite imagery as MGW/ZZV have scattered out
to mostly sunny skies. This trend should continue through the
rest of the day with most of these clouds clearing by late
evening, though some patches of scattered/broken coverage may
linger into overnight hours. Winds are light across the area and
should remain that way through the night before a strengthening
and better established southeast flow sets up after 12Z Friday.

.Outlook...
VFR conditions are expected Thursday and Friday.

The probability of showers and isolated thunderstorms increases
Friday night into Saturday which will come with increasing
probabilities for restrictions as well.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...Frost Advisory from midnight tonight to 9 AM EDT Friday for
     PAZ007-013-014-020-022-077-078.
     Freeze Warning from midnight tonight to 9 AM EDT Friday for
     PAZ008-009-015-016.
OH...Frost Advisory from midnight tonight to 9 AM EDT Friday for
     OHZ039>041-048>050-057>059-068.
WV...Frost Advisory from midnight tonight to 9 AM EDT Friday for
     WVZ001.
-- End Changed Discussion --

&&

$$

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