398
FXUS61 KPBZ 150918
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
418 AM EST Fri Nov 15 2024

.SYNOPSIS...
Intermittent drizzle and or light rain will continue today,
along with extensive cloud coverage. Dry conditions will resume
Saturday along with seasonable temperatures.

&&

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

- Light rain/ drizzle will linger today.
- Another day with limited diurnal range in temperature.

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

Ample low level moisture and slight lift will support
intermittent areas of drizzle today, and thick low overcast
stratus and morning fog. This will also result in a limited
diurnal range in temperatures over the course of the day. 10th
percentile NBM guidance was used for daytime highs given
yesterday`s performance under similar conditions.

Flow will veer to the west / northwest during the day, providing
the small amount of lift needed to squeeze some drizzle out of
the saturated boundary layer.

&&

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

- Drying and warming trend begins Saturday and lasts through
  the weekend
-------------------------------------------------------------------

Patchy drizzle and/or light showers chances will continue
overnight, with the highest probabilities northwest of
Pittsburgh and across the ridges. Building high pressure across
the Great Lakes by early Saturday will help return dry weather
to the area through the weekend.

Upper ridging builds directly overhead by Sunday with a modest
boost to warm advection Saturday into Sunday. This will help
drive temperatures back into the upper 50s to lower 60s on
Sunday afternoon.

&&

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

- Rain returns Tue/Wed with additional chances through late week
- High uncertainty remains with a late week system
-------------------------------------------------------------------

Ensembles show a better agreement Monday into Tuesday for a
flattened ridge overhead and mild weather continuing.
Temperatures should generally warm a couple degrees each day,
ending up nearly 10 degrees above average by Tuesday.

Greater uncertainty arises by Tuesday as a shortwave ejects out
of the Southwest and into Midwest. This weakening wave may bring
showers to the area by Tuesday afternoon though it appears that
significant rain chances will be slow to move east from the
central US as ensembles hint at blocking with the longwave
trough remaining anchored somewhere near NM to TX area.

Considerable uncertainty enters the forecast by late week,
highly dependent on the evolution of low pressure over the Great
Lakes and Ohio Valley regions. There is low potential for a
stronger system, which could bring snow chances to the area,
however, other solutions (e.g. weaker wave) show higher
probability at this time. Daily temperatures will also be
closely tied to the evolution of this system, so have kept close
to NBM mean values for now.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
Lingering moisture in the region plus the slow exit of the upper
trough will maintain MVFR to IFR cigs with pockets of light
rain/drizzle and its associated vsby drops. A late morning to
the afternoon wind shift with a weak frontal boundary may
briefly disrupt cigs with some lift, but model soundings suggest
any improvement are generally short-lived as rising motion
fosters another period of light rain/drizzle.

Ensembles favor greater restriction improvement potentially
Friday night into Saturday due to increasing subsidence
experienced in the region (IFR probabilities lower notably after
00z). Favored a more pessimistic vantage as stout boundary layer
moisture will be difficult to erode purely through subsidence,
resulting in a bkn to ovc MVFR/IFR stratocu layer that lingers
into Saturday morning.

Outlook....
High pressure and height rises aloft Saturday will offer
cig rises through the day, but moisture trapped beneath the
post-frontal inversion may limit VFR potential. Hi-res modeling
suggests 50-70% probability of MVFR cigs lingering into Saturday
evening and exhibiting a gradual reduction in MVFR cig
likelihoods through Sunday morning from the southwest to the
northeast.

Confidence is high that VFR will develop areawide by Sunday
afternoon before the next weak disturbance crossing Monday
offers increased rain/restriction probabilities that favor
northwest PA.

&&

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

&&

$$

SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...Rackley/88
AVIATION...Frazier