057
FXUS61 KPBZ 262329
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
729 PM EDT Thu Sep 26 2024

.SYNOPSIS...
Broad low pressure over the Tennessee River Valley and influence
from Hurricane Helene remnants will create periodic rain
chances through Monday. Gusty wind is likely during the Friday
afternoon to early evening period.

&&

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

- Dry conditions persist with low probability for rain south of
  Pittsburgh
- Limited diurnal ranges continue overnight
- Wind Advisory in effect for eastern Tucker (12pm to 7pm).
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Ridging and subsidence between the Tennessee River Valley
closed low and the New England trough will maintain dry weather
through most of the night.

Northward movement of the surface low associated with Hurricane
Helene may increase upslope components around the WV high
terrain to increase shower chances heading into the dawn hours
Friday.

The moisture axis stretching from the Gulf through Maine will go
unchanged with little airmass movement expected into Friday
morning. This excessive cloud cover will continue to moderate
diurnal swings and lend to above normal temperature to start the
day Friday.

Probability of strong wind gusts, 45mph to 50mph, is considered
high (above 90%) using Hi-Res ensemble guidance for the ridges
of eastern Tucker after 12pm Friday; Wind Advisory remains in
effect. Winds will prevail from the east and are associated with
Helene`s large wind field as it tracks through Kentucky/Tennessee
region. Expansion of the Advisory may be needed for Preston,
Fayette, or Westmoreland County.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
KEY MESSAGES:

- Wind gusts will decrease Friday night.
- Light rain from Helene may pass through portions of the
  region.

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Light rain, associated with the remnants of Helene, will likely
be ongoing Friday night into early Saturday morning. However,
the probability of amounts greater than or equal to a quarter of
inch is low; less than 15%. Winds will decrease Friday evening
as Helene continues to weaken; extension of the Advisory passed
7pm is unlikely for the ridges.

Clouds will continue to linger with outflow associated with
Helene into Saturday afternoon.

Temperatures will trend above average (by 10 degrees) through
this time period with deep southerly flow.

&&

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

- Rain chances will be dependent on how quickly the closer upper
  low transitions eastward Sunday into Monday
- Ensembles favor a trough kicker to arrive Tuesday into
  Wednesday, with dry and seasonable weather developing
  thereafter
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Latest model trends favor a gradual eastward track of the closed
upper low that will experience slow weakening Sunday into
Monday. Subtle low positioning will be key in determining areas
of greater forcing, but means values suggests rainfall chances
peak Sunday for lower elevations locations, trending to eastern
facing slopes on Monday. Probabilities remain very low on
receiving drought-busting rainfall, with 24 hour chances of
exceeding 1" peak at only 20% for most locations.

Ensembles favor the weakening area of low pressure to shift
toward the Atlantic coast Tuesday into Wednesday morning thanks
to a kicker upper trough diving out of central Canada. This
feature would likely offer a last chance for precipitation ahead
of a surface cold front before a drier and more seasonable
airmass develops. There are scenarios where the broad low
pressure sags south rather than moving east while Great Lakes
ridging develop mid week; if this plays out, look for rising
temperature trends and potentially a reintroduction of low
probability afternoon thunderstorms.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR is expected through Friday morning with mid level cloud cigs
ahead as tropical moisture streams northward. The exception is
DUJ, where an upslope easterly flow should result in MVFR cigs
by morning. Light rain is likely at MGW and ZZV toward daybreak
as the moisture and ascent on the northern side of Helene
increase. Elsewhere, a band of light rain is expected to lift
north across the region Friday afternoon, with a period of MVFR
possible. Low VFR cigs should return for most airports after
the rain ends.

A tightening pressure gradient will result in gusty E wind on
Friday. Gusts from 20-25 kt are likely for most locations, with
gusts to 30kt with some downsloping at LBE.

.Outlook...
Cig restrictions are possible at FKL and DUJ Friday
night/Saturday with easterly flow. Occasional restrictions and
light rain are likely Sunday through early Tuesday as low
pressure drifts across the Upper Ohio Valley region.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...Wind Advisory from noon to 7 PM EDT Friday for WVZ514.

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Hefferan/Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...WM