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000
FXUS61 KPBZ 241716
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
116 PM EDT Wed Apr 24 2024

.SYNOPSIS...
Showers will continue this morning with the passage of a cold
front. Dry weather returns tonight through Friday as high
pressure builds across the region. Shower chances return Friday
night and Saturday with a warm front.

&&

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

- Showers will gradually taper off later today after the passage
  of a cold front

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

Updated the forecast to input the hourly temperatures and dew
points and trend them into the mid morning hours. The forecast
is on track for the most part.

Previous discussion...The latest surface analysis shows a
prefrontal trough crossing central PA, with the main cold front
across Lake Erie to NW Ohio. Showers associated with the
prefrontal trough and a low level jet will continue to exit from
west to east early this morning. Additional showers will soon
follow with the crossing cold front and shortwave trough axis.

Dry weather should return by mid to late afternoon as surface
high pressure begins to build across the region under a broad
mid and upper level trough. Cold advection in NW flow, and
moisture below a strengthening subsidence inversion, should
keep a persistent stratocu cloud layer across the region through
at least this evening. Temperatures will recover some behind the
cold front, though will still be around 10 degrees below
average.

&&

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

- Freeze watch continues north and west of Pittsburgh
- Some frost possible outside of the freeze watch
- Dry and warmer Thursday and Friday
- Showers return Friday night with a warm front
----------------------------------------------------------------

Clouds are expected to persist into the evening with moisture
below a subsidence inversion, and cool NW flow. The highest
amount of uncertainty exists in how fast the cloud will clear
overnight. Clearing is likely from north to south as high
pressure builds further across the Lower Great Lakes and Upper
Ohio Valley region, though the speed that this occurs is in
question. Model soundings indicate the clouds will hold from
near Pittsburgh and points S-SE much of the night. HREF cloud
cover guidance also indicates this potential. Clearing will
likely occur in the far north after midnight. With this
uncertainty, maintained the Freeze Watch as is in coordination
with surrounding NWS offices. Frost is possible outside of this
watch, but will be highly dependent on the cloud cover.

Otherwise, dry weather is expected through Friday as the high
tracks slowly eastward to the New England region. Southeasterly
flow, warm advection, and rising 100-500mb heights with a
building ridge should return temperatures back to the 60s and
70s.

The ridge axis will shift east of the area Friday night.
Warm, moist advection ascent will increase Friday night in
southwest flow aloft behind the ridge axis, with showers
overspreading the region.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
KEY MESSAGES:

- Much warmer through the weekend
- Highest chance for showers on Saturday, and again Monday
  through Tuesday
-------------------------------------------------------------------

Model ensembles indicate the initial shortwave and warm
front supported rain will continue to cross the region on
Saturday. The front is expected to lift north of the region
Saturday night, as a strong ridge builds across the SE CONUS to
the Upper Ohio Valley region.

Mainly dry weather is expected Saturday night and Sunday with
the ridge axis across the area. There could be enough diurnally
driven instability to result in an isolated afternoon
thunderstorm Sunday, though most of the day should be dry, with
temperatures in the upper 70s to the mid 80s. 1000-500mb height
approach 583dm Sunday into Monday, with 850 mb temperatures
peaking around 14 deg C.

Model ensembles indicate the ridge should slowly shift eastward
to the East Coast late Monday and Monday night, as the next
shortwave trough and surface cold front approach from the
Midwest. Scattered showers and thunderstorms are possible Monday
with building diurnal instability in moist SW flow ahead of the
trough. More numerous showers and possible thunderstorms are
expected Tuesday as the trough/cold front cross the region.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
Some isolated showers will continue to move across the northern
forecast area this afternoon and into the early evening likely.
Variable ceilings will continue through the afternoon given the
mix of VFR and MVFR/IFR conditions in place. The cold front has
effectively moved through the area with winds shifted around to
the northwest in most instances. The daytime heating in the
south is creating a gradient and showing at the terminals as sky
conditions show breaks in the cloud cover in the south.

MVFR cigs looks to remain through the evening and overnight
hours with improvement possible toward 12Z tomorrow morning.
Its not out of the question to still get some breaks at times in
the cloud cover through the TAF period as well.

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

The probability of showers and isolated thunderstorms increases
Saturday. This will come with additional restrictions likely.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Watch from 10 PM EDT this evening through Thursday
     morning for PAZ007>009-013>016-020-022-077.
OH...Freeze Watch from 10 PM EDT this evening through Thursday
     morning for OHZ039>041-048-057.
WV...None.

&&

$$

SYNOPSIS...WM
NEAR TERM...WM/Shallenberger
SHORT TERM...WM
LONG TERM...WM
AVIATION...Shallenberger