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000
FXUS61 KPBZ 231804
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
204 PM EDT Tue Apr 23 2024

.SYNOPSIS...
Dry, warm weather is expected today with marginal fire weather
concerns. A crossing cold front will increase precipitation
chances tonight and early tomorrow. A warming trend is expected
to close out the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Dry and seasonably warm weather with wind gusts up to 30mph
  will result in marginal fire weather concerns today.
- Showers arrive overnight with a passing cold front.
------------------------------------------------------------------

Shortwave ridging will continue its eastward progression as a
shortwave trough moves in through the near term. Accelerated
flow is expected in an increasing gradient. Stout mixing up to
~800mb is expected to allow wind gusts up to 20 to 30mph during
the day today.

As of 10am, the mixing is already over-performing most
guidance, hence, opted to increase the temperatures into the day
today towards the 90th percentile and lower the dewpoint towards
the 10th percentile as the atmospheric profile slowly taps into
a dry cap.

Low relative humidities and heightened wind will come together
to create marginal fire weather concerns today across the
forecast area. A fire weather SPS is in effect in West Virginia
and Pennsylvania through 8pm to highlight the threat.

Shower chances increase in pre-frontal convergence and along a
passing cold front this evening and overnight tonight. Precipitation
totals have trended down slightly with the latest update. There
is only about a 30% chance of exceeding a quarter of an inch
along I-80,with roughly a 15% to 25% chance elsewhere. This
means Pittsburgh will likely not exceed its all-time April
rainfall with this event.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
KEY MESSAGES:

- Few showers possible Wednesday, followed by a frost/freeze
  Wednesday night.
- Dry and warmer Thursday.
----------------------------------------------------------------

Post-frontal cold advection will force saturation in a low deck
on Wednesday. This, combined with the cold advection itself,
will keep daytime high temperatures a few degrees below average
on Wednesday. Quasi-unstable, low-level thermodynamic profiles
in saturation may lend to a few shallow daytime showers,
enhanced by a couple passing 500mb shortwaves.

Overnight, drier air will advect in from the north, reducing
cloud cover along with it. Clearing combined with calm surface
conditions and anomalously cool low levels will lead to
moderate confidence in a freeze north and west of Pittsburgh
(greater than 50%), with a frost possible elsewhere. A Freeze
Watch has been issued accordingly.

The return of surface high pressure on Thursday will lend to
another dry day with mostly clear skies. Surface heating will
allow a slight rebound in high temperatures.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
KEY MESSAGES:

- Much warmer and unsettled through the weekend.
- Forecast uncertainty increases considerably next Tuesday.
-------------------------------------------------------------------

Model ensembles indicate ridging, warm advection, and rising
1000-500mb heights will result in dry and warmer weather on
Friday. The ridge will shift east of the area Friday night and
Saturday, as a shortwave trough embedded in southwest flow aloft
crosses the region. Showers will return with the approach and
passage of the wave.

The ridge is then progged to become reestablished across much
of the Eastern CONUS through Sunday night. Dry weather is
expected most of the period from Saturday night through Sunday
night, through diurnal instability could be sufficient for
isolated to scattered showers and thunderstorms.

Rising 1000-500mb heights, and 850mb temperatures around 14 deg
C, should result in highs as much as the upper 70s on Saturday
(most likely for eastern Ohio), and the mid 80s on Sunday (most
likely for the lowlands).

Multi-model clusters are incredibly consistent with the 500mb
pattern through Monday, but uncertainty increases considerably
thereafter. Some clusters have the maintain the eastern ridge
which would allow for continued warm weather; other clusters
develop quasi-zonal flow or eastern troughing, which would tend
cooler and more unsettled.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
High pressure will keep VFR conditions in place through this
afternoon and evening. Winds gusting from the westsouthwest up
to 25 knots will continue before decoupling just after 00Z.
Expect cigs to begin lowering with the approach of a cold front.
Showers are expected to impact ZZV by 03Z and then PIT by 06Z.
MVFR at terminals will worsen to IFR and below through the
remainder of the overnight and into Wednesday morning. Frontal
passage is expected by 12Z but IFR and below conditions may
remain through the end of the TAF period.

.Outlook...
Widespread MVFR to potential IFR (DUJ/FKL) conditions are
expected to increase Wednesday with the passage of a cold front.

Cig improvements will likely develop late evening Wednesday with
incoming dry, cold air in the wake of the front.

The probability of showers and isolated thunderstorms increases
Saturday.

&&

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

&&

$$

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