Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 251445
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1045 AM EDT Mon Mar 25 2024

.SYNOPSIS...
Fire weather danger is expected today due to gusty conditions
and low relative humidity, a Special Weather Statement was
issued in collaboration with our partners. Downslope wind gusts
this evening into tomorrow have prompted a Wind Advisory for
areas east and southeast of Pittsburgh. Rain chances increase
after 6am Tuesday, ahead of a cold front.

&&

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

- A Special Weather Statement (SPS) was issued in collaboration
  with our Ohio and West Virginia partners for fire danger
  today. Low relative humidity and gusty conditions will result
  in an increased risk of fire start and spread.
- A Wind Advisory has been issued for downslope potential late
  this evening and into Tuesday.

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

This 12Z PIT sounding suggests that very dry air at 1,000ft to
4,000ft will mix to the surface with diurnal heating and prompt
a second day of very low relative humidity values. MinRH values
will range from 20% to 25% for West Virginia and eastern Ohio;
30% to 35% for PA counties. Along with dry conditions, wind
gusts between 15mph to 25mph will be observed throughout the
day as a disturbance over the Plains strengthens and increases
the gradient wind field. Therefore, fire weather danger will be
a concern throughout the evening and it is advised to exercise
caution if handling open flames or equipment that creates
sparks. A Special Weather Statement was issued in collaboration
with surrounding WFOs and the State Foresters in West Virginia
and Ohio. Despite low relative humidity in Pennsylvania, the 10
hour fuel moisture was measured above the 10% threshold level of
concern. Therefore, no Special Weather Statement was issued for
western PA.

A Wind Advisory was issued along the ridges of Pennsylvania and
West Virginia after 7pm this evening due to downslope winds.
Probabilities are high that localized wind gusts over 50mph from
the southeast could create impacts: unsecured objects may blow
away, tree limbs could be blown down, and power outages may
increase early Tuesday morning.

Otherwise, dry and above normal conditions are likely today with
a building ridge over the Ohio River Valley. Temperatures will
10 to be 15 degrees above the climatological normal.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
KEY MESSAGES:

- Strong wind gusts (+50mph) along the ridges of West Virginia
  and Pennsylvania is expected tonight into Tuesday afternoon
  due to downsloping; Wind Advisory continues into early Tuesday
  afternoon.
- 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. Hi-Res guidance probabilities are considered high
(above 80%) over the ridges for 50mph wind gusts from the
southeast through 1pm Tuesday due to downsloping. The Wind
Advisory continues for the Laurel Highlands and West Virginia
ridges.

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 /14Z 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...Wind Advisory from 7 PM this evening to 1 PM EDT Tuesday for
     PAZ073>078.
OH...None.
WV...Wind Advisory from 7 PM this evening to 1 PM EDT Tuesday for
     WVZ510>514.

&&

$$

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


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