PBZ issues Area Forecast Discussion (AFD) at Nov 10, 3:31 AM EST898
FXUS61 KPBZ 100831
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
331 AM EST Sun Nov 10 2024
.SYNOPSIS...
Widespread rain will return this morning with low pressure, with
highest probabilities in the afternoon. Showers may linger into
Monday, especially north of I-80. Additional rain chances are
possible Thursday with a cold front.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- High confidence in widespread rain today, with highest
probabilities this afternoon.
- Rain will begin before sunrise in eastern Ohio.
-------------------------------------------------------------------
Increasing clouds and warm advection have kept area temperatures
above most guidance, with little drop from early evening. The
hourly forecast has been nudged accordingly. The 00z PIT sounding
and current surface obs continue to show very dry air in place.
Dewpoints in the mid 20s will slow onset of early morning rain,
though moisture advection southwesterly flow aloft will help
thicken mid/upper level clouds.
Low pressure will cross the Great Lakes today, with deep
southwesterly flow allowing Gulf moisture to stream into the
area. Ensemble mean precipitable water values near 1.3" are near
the record daily maximum, which should help us outperform recent
lackluster rainfall events. Scattered light showers are expected
to spread across the area this morning, initially battling low-
level dry air. More steady rain becomes likely this afternoon as
a crossing 45-55 kt low-level jet enhances low-level
convergence.
Ensemble probability for a wetting rain (at least 0.10") remains
very high at 95-100% areawide. Similarly, at least 0.25" is 90+%
with a 60-75% chance of a half an inch. The highest reasonable
scenario (p90) remains near an inch. Realization of this will
likely rely on tapping into whatever marginal instability can
develop; instability likely won't be surface-based given the
low-level warm advection regime, so the threat for severe
weather is low. This system will be progressive overall, but
wouldn't rule out some localized totals nearer to the 75th-90th
percentile in some of the maximized higher rainfall rates.
Continued warm advection ahead of the cold front this evening
will likely boost area temperatures a few degrees into the
overnight, with frontal and trof axis passage finally occurring
after 06z. Lingering rain will diminish behind these features.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- Lower confidence rain Monday into Monday night.
- Dry and cooler Tuesday and Wednesday.
-------------------------------------------------------------------
A secondary trough will cross the Great Lakes on Monday with a
trailing cold front and better cold advection following Monday
night. This feature should reintroduce showers to the forecast
Monday afternoon into the overnight, though focus will be
primarily north of Pittsburgh. Extent and longevity of coverage
remains somewhat uncertain, dependent on the depth and
progression of the upper wave. A slower departure would favor
cooler temperatures and lingering precip chances through Monday
night while a faster pattern favors warmer, drier
conditions. Regardless, much more seasonable low temperatures
are expected Tuesday morning given arrival of colder air and
building high pressure.
Upper troughing will slide east on Tuesday as ridging and
surface high pressure builds over the Great Lakes. This favors
dry weather and temperatures closer to the seasonal average.
Wednesday morning will be our next chance of seeing freezing
temperatures, as most of the area outside of northern WV has a
90-100% chance of reaching 32F.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:
- Better rain chances Wednesday night into Thursday but still
some uncertainty.-
- Highs a few degrees above normal.
-------------------------------------------------------------------
Ensembles agree on another round of low pressure crossing the
Great Lakes sometime late Wednesday into Thursday, though
confidence remains low in the details. This introduces Chance
PoPs into the forecast overnight Wednesday through Thursday.
High pressure looks likely by Friday as drier conditions return
and continue into the weekend. High temperatures will run a few
degrees above average.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
Expect a BKN to OVC layer to roll through the area tonight as
moisture increases ahead of approaching low pressure that will
bring widespread rain and restrictions on Sunday.
Cloud bases lower further through the dawn hours on Sunday and
restrictions are favored to overspread the region coincident
with precipitation as low level saturation is achieved. Latest
ensemble probability indicates most likely arrival time of
showers and MVFR CIG/VIS in rain around 12z at ZZV, 17z at PIT,
and 19z at LBE.
MVFR conditions are high probability (90+%) with a 50-70%
chance of both IFR CIG and VIS as a low level jet aids in
forcing and more moderate rain, but timing of this is currently
just encompassed at the end of the PIT TAF period. Visibility
and ceilings will improve some headed into the overnight hours
Sunday night, but lingering low- level moisture overnight
doesn't bode very well for a high confidence return to VFR.
.Outlook...
A passing cold front early Monday will decrease the potential
for rain. However, restrictions may linger into late Monday
morning due to residual low-level moisture and cold advection.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Rackley
NEAR TERM...Rackley
SHORT TERM...Rackley
LONG TERM...Rackley
AVIATION...Shallenberger
Source:
PBZ issues Area Forecast Discussion (AFD) at Nov 10, 3:31 AM EST---------------
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