Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 250755
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
355 AM EDT Mon Mar 25 2024

.SYNOPSIS...
Dry and warmer today under high pressure. Rain chances return
Tuesday as an upper level disturbance swings through the region.

&&

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

- Dry day. Warmer temperatures. Increasing wind gusts this
  afternoon.
- Limited fire weather threat is expected for West Virginia and
  eastern OH due to low relative humidity and increasing wind
  gusts. A Special Weather Statement may be need.

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

Deep surface high will drift across northern New England today.
As this high moves northeastward, an upper level ridges will
amplify over eastern PA. This setup will mean plenty of
subsidence over the region leading to another dry day with
minimal cloud cover. Strong warm air advection will push highs
10+ degrees above normal.

With the broad surface high over New England, and a deepening
system over the central US, the surface pressure gradient will
tighten today leading to increased surface wind gusts this
afternoon. Gusts of 20 to 30 mph are possible, with the
strongest over the ridges.

A very dry atmosphere will remain in place today. RH values may
drop into the upper teens to lower 20s over portions of the
region this afternoon. Surface winds will also strengthen this
afternoon. This will increase the fire weather threat as the
day progresses.

&&

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

- Strong wind gusts (over 40mph) due to downsloping along the
  ridges of West Virginia and Pennsylvania is possible tonight.
- Rain chances return to the region Tuesday with an approaching
  disturbance.
- Scattered light showers continue Wednesday with the slow
  crossing of a cold front.

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

Upper level ridge will remain parked over eastern PA tonight.
This will slow the eastward movement of an upper level wave
rotating northeastward on the eastern side of the massive
central US trough. This should keep the area dry tonight.

A tight surface pressure gradient, and crossing low-level jet,
will increase the risk for strong wind gusts over the ridges
tonight. Latest probabilities keep the wind gusts just below
advisory levels. NBM probs for >40 mph are 40% to 50%, with
probs of >45 mph around 15% to 20%. The wind direction may not
be just right for optimal downsloping, and it appears a large
low level inversion will develop tonight as warmer air continues
to push northward aloft.

Still seeing some timing issues with the onset of rain on
Tuesday and how far east it will push before either stalling or
dissipating. The amplified ridge over the east coast will
begrudgingly move eastward on Tuesday. The shift will be in
response to a shortwave trough that will eject eastward from the
central US trough. Much of the energy from the shortwave may be
spent fighting the ridge. Models are showing a descent moisture
plume passing through the region on Tuesday, which will aid in
bring widespread rain to the area. It does appear that as the
rain moves eastward, it will decrease in coverage and intensity.
Probabilities for >0.25 inches for the eastern half of the
forecast area are 40% to 60% while over the western half are 60%
to 70%. Looking at probs >0.50 seeing around 15% to 45%, with
the higher numbers over Ohio. Rainfall will be generally light
with the higher QPF mainly over Ohio.

With rain and increased cloud cover, highs on Tuesday will drop
a few degrees, but still remain above normal.

With the slow eastward movement of a cold front, due to the
stubborn east coast ridge, the risk for scattered showers will
continue on Wednesday. However, a large upper level dry slot
will spread across the region ahead of the front, greatly
limiting rainfall amounts. Its not out of the question that much
of the rain directly along the front will dissipate Wednesday
afternoon.

Temperatures remain above normal on Wednesday.

&&

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

- Dry conditions are favored Thursday and Friday.
- Unsettled weather returns for the weekend.

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

Dry conditions are more likely with the reestablishment of high
pressure Thursday and Friday. Although an isolated shower cant
be completely ruled out over the ridges on Thursday.

Eastern CONUS ridge will try to amplify over the weekend.
However, it appears as if we will be located right at the top of
the ridge. Shortwaves, riding over the ridge, will keep in the
risk for scattered showers both Saturday and Sunday. Above
normal temperatures will remain through the weekend.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
VFR will prevail through the TAF period. Tightening pressure
gradient will gradually strengthen southeasterly winds through
the day. Downsloping is expected to enhance gusts in the LBE
area, though a strong inversion and poor low-level lapse rates
will likely limit the depth of the boundary layer... keeping
strongest winds aloft. Occasional gusts of 10-20 kts are
possible during the day, increasing to near 30 kts for LBE by
00z Tuesday. With limited gusts at the surface and a strong
LLJ, low-level wind shear will become an issue near the end of
the TAF period and into early Tuesday.

High clouds will increase today ahead of the next approaching
low pressure system.

.Outlook...
High pressure maintains VFR conditions through tonight with
only mid and high clouds expected. Rain and restrictions return
Tuesday and Wednesday with the approach and passage of a cold
front. VFR then returns Thursday and Friday under high pressure.

&&

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

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...22
LONG TERM...Hefferan/22
AVIATION...Cermak/Rackley


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