496
FXUS61 KPBZ 111727
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
127 PM EDT Sun Aug 11 2024

.SYNOPSIS...
Mostly dry conditions and slightly below-normal temperature
are expected through early week. Temperature begins to moderate
by mid-week with broad rain chances possible by the end of the
week.

&&

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

- Max/Min temperature remain a couple degrees below normal
- Chance of showers north of I-80 this afternoon and again
  tonight
-------------------------------------------------------------------

There is high confidence in the weather pattern today and
tonight, with a strong upper-level low in vicinity of Toronto,
and a jet streak advancing newd to aid in the advance of a weak
cold front into the upper Ohio Valley.

The jet will advance newd today across the region, fostering
enhanced low-level convergence near and north of I-80 during
peak heating. A deeply mixed boundary layer and modest moisture
within this convergence zone likely will support the development
of scattered showers in the 16-18Z timeframe.

Owing to the spatial uncertainty in model placement of showers,
NBM inherently underplays the PoPs in such situations, so have
made some manual adjustment to PoPs this afternoon and again
this evening as the upper low`s trough axis advances across Lake
Erie and potentially reinvigorates showers overnight in the I-80
corridor.

Any showers likely will be gone before sunrise Mon morning, and
could amount to little more than 0.1" in localized areas north
of I-80. Most areas will remain dry.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Max/Min temperature remain a couple degrees below normal
- Possibility of a shower or two Tuesday afternoon
- High confidence in the weather pattern
-------------------------------------------------------------------

Thru Tue, there remains high confidence in the weather pattern
as ensemble clustering depicts very little deviation from the
grand ensemble mean.

An amplified mid-level ridge will build across the central CONUS
and into Canada as sern-CONUS high pressure remains in place.
This pattern leaves the upper Ohio Valley beneath broad nwly
flow aloft and building sfc high pressure as the Canadian low
weakens and exits. Overall, the pattern is suggestive of
general strong heating offset by modest cold advection, diurnal
fair-weather cu and deep mixing of the boundary layer.

The net result for Mon will be dry weather, nwly sfc wind that
may exhibit modest diurnal gustiness, and occasional clouds with
daily maxima climbing toward the upper 70s-lower 80s.

Tue afternoon may see a weak disturbance advance across the
region within this nwly flow aloft, potentially invigorating a
few showers. At this time, the probability of showers is low
(around 20%), but bears watching for potential increase if
moisture return occurs.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
KEY MESSAGES:

- Max/Min temperature closer to normal mid- to late-week
  timeframe
- Rain chances increase late week amid moisture return and
  greater forecast uncertainty in the weather pattern
-------------------------------------------------------------------

Medium confidence remains thru mid-week as the central-CONUS
ridge axis shifts ewd, suggesting moderating temperature for the
upper Ohio Valley by Wed.

Ensemble clustering suggests increasing uncertainty in the
weather pattern by Thu as upper-level troughs, progressing ewd
from the Pacific NW region, potentially weaken the downstream
ridge.

By Day 6 (Aug 16), the strength of the lingering ridge is
considerably questionable given evidence of a multimodal
distribution, as some ensemble members show a more-amplified
ridge axis while others depict heights considerably below the
ensemble mean.

All told, a general evolution of the upper-level pattern toward
wnwly flow aloft seems likely by week`s end, supportive of
progressive embedded shortwave troughs and greater potential for
showers and storms as moisture returns to the region.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
VFR conditions will continue through the TAF period with high
confidence for terminals south of I-80. Here, scattered to
broken fair weather cumulus are expected to persist through the
afternoon. Deep mixing will allow wind gusts in the 15 to 20
knot range as well, out of the west.

North of I-80, at FKL, passage of a shortwave trough, along
with marginal moisture, may allow for a few showers this
afternoon and evening, with a brief drop to MVFR conditions
possible. Best chance will be between 18 to 22Z, handled via
TEMPO group.

Tonight, the brief shower chances continue at FKL, while most
other locations continue to enjoy VFR conditions and decreasing
wind, although a few high clouds may stream across the sky.
Another round of scattered to broken cumulus is likely by midday
Monday, along with light W/NW wind.

.Outlook...
General VFR is expected through early week as surface high
pressure builds under broad upper troughing.

&&

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

&&

$$

SYNOPSIS...Kramar
NEAR TERM...Kramar/MLB
SHORT TERM...Kramar
LONG TERM...Kramar
AVIATION...CL