535
FXUS61 KPBZ 110543
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1243 AM EST Tue Nov 11 2025

.SYNOPSIS...
Snow showers continue through Monday night with minor impacts in
the lowlands. Lake effect snow bands expected along and north
of Interstate 80 with localized impactful accumulation, and
upslope flow in the PA and WV ridges will also result in
snowfall impacts. Snow will taper off on Tuesday outside of
Interstate 80 and the ridges, though another disturbance on
Wednesday will reintroduce rain and snow showers.

&&

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

- Snow continues across the area with generally an inch or less in
  the lowlands
- Highest amounts in the ridges with upslope flow and I-80 corridor
  with lake effect bands
- Snow tapers off on Tuesday with gusty wind
---------------------------------------------------------------

A deep upper low parked across the Great Lakes region with northwest
flow in the wake of low pressure sliding through the Northeast has
turned on the lake effect snow machine and will bring impactful snow
to parts of the area through tonight.

Starting with the lowlands... Tonight, roadway temperatures are
already below freezing as air temperatures continue to plummet into
the 20s overnight. Snow showers remain and accumulation on all
surfaces will become more likely, though coverage still will remain
scattered and not expecting more than an inch or so. The majority is
likely to see less, but it`ll likely look more white on Tuesday
morning than it did Monday morning.

For the I-80 corridor... this is where the most impactful snow is
expected with this event, though the highest accumulations will be
very localized. Lake effect snow showers are underway. Banding is
currently setup over northeastern Venango/southwestern Forest/
northern Clarion/ northern Jefferson (PA) Counties. Analysis of the
12z HREF/current CAMs, elicit a moderate confidence in the location
of the shifting lake-effect bands. Currently, the strong banding
over the northern counties is the main focus. CAMs are suggesting a
shift to the south impacting Mercer/ northern Butler/ northern
Armstrong Counties before there is a shift in the flow. The likely
evolution of this lake-effect banding is that the current
northwesterly flow will pivot to the east coincident with the well-
aligned, backing wind pattern. HREF snow accumulation assumes a 10:1
snow to liquid ratio which, for this case, is too low, and more
likely around 16-18:1. The 90th percentile QPF, which is a
reasonable representation of the highest liquid equivalent within
lake effect bands, is around 0.50"-0.70". So, this points toward
some highly localized amounts within those counties up to the 8"-12"
range. Outside of the band, amounts will be much less and in the 2-
4" range. The takeaway message is that part of those counties is
likely to see impactful accumulating snow tonight with greatly
reduced visibility and hazardous travel conditions while lesser
amounts are expected elsewhere in the county.

For the ridges... upslope enhancement will aid in higher totals for
both our PA and WV ridges. As discussed, the boundary layer flow
will gradually back through tonight and thus not result in
persistent favorable direction for upslope along all of our ridges.
Initially, the heaviest snow and highest accumulation should be in
the WV ridges with a north-northwest flow maximizing orographic
ascent. As flow backs, it`ll become more orthogonal to the PA ridges
and transfer better rates and accumulation there. With colder
surface temperatures, it should be easier to lay on all ground
surfaces and create impactful travel conditions overnight. Rates may
exceed 1"/hour.

Through the day tomorrow, flow will back more and eventually turn
west to west-southwest and taper off the lake enhancement for our
area. It`ll linger longest along and north of I-80, as well as in
the PA ridges, with a broader coverage of light snow showers
possible aided by increased synoptic ascent with a passing mid-level
wave. Some additional light accumulation is possible. Drier air
finally advects in from the west on the back side of the mid-level
trough as it moves east and will shut off the snow entirely by late
afternoon. The other story of the day will be gusty wind with a
tight pressure gradient and diurnal mixing into 25-35 knot low level
flow with momentum transfer resulting in surface gusts to 30 mph.
With high temperatures in the low to mid 30s, wind chill values will
hover in the 20s for most of the day. Eastern Tucker County likely
sees values into the negative single digits especially early Tuesday
morning.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:

- Passing disturbance maintains lake effect snow showers north of
  I-80 and in the ridges on Wednesday
----------------------------------------------------------------

Upper troughing remains dominant on Wednesday with transient surface
ridging maintaining mostly dry conditions south of Pittsburgh. To
the north and in the ridges, additional lake effect and upslope snow
showers are likely with PVA and a weak surface trough passage. Flow
should remain mostly out of the west thus keeping the best lake
effect tucked closer to the lake itself. We`ll struggle to get a
good shot of cold air with surface flow out of the southwest and
highs reaching the low to mid 40s across the area, so surface
temperatures will be much more marginal with this event. NBM
probability for >1" is low in our area (<20%) which makes sense
given the environment, and any accumulation may be confined to
elevated surfaces. Wind will still be gusty but with moderating
temperatures won`t see a wind chill impact.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
- Dry weather with moderating temperatures Thursday and Friday
- Temperatures closer to normal heading into the weekend
-------------------------------------------------------------------

The long term begins with northwesterly flow and subtly rising
heights as the upper trough kicks eastward into Atlantic Canada and
an upper ridge noses into the area from the central CONUS. At the
SFC, high pressure settles in from the west and dry conditions are
expected. With subtle height rises, temperatures continue to trend
upwards through late week, approaching average by Friday. A slow
moving warm front looks to return rain chances by Friday night,
before more widespread rain chances are expected with the parent low
later this weekend.

Ensembles are in good agreement that the ridge gets kicked eastward
by a western trough on Saturday, residing almost overhead. However,
they quickly diverge on Sunday with their depth and location of said
western trough. A couple clusters feature height falls for our area
as an open wave presses eastward and breaks the ridge down shunting
it eastward. Another cluster slows the pattern down by developing a
cutoff low near the four corners allowing ridging to remain
overhead.

Either way, both scenarios hint at the ridge moving eastward and the
return of upper troughing to end the weekend or begin next week.
This would bring cooler temperatures and more unsettled weather, the
difference remains in just how fast we get there. For now the
forecast features above average temperatures lasting through Sunday
and then dropping to begin next week. Precipitation chances look to
remain elevated into early next week.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
General VFR to high MVFR ceilings persist across the region
early this morning as isolated lake effect snow streamers
continue. IFR restrictions are possible at times in moderate
snow, but this will likely be limited to FKL and possibly DUJ
this morning. Snow shower activity north of Pittsburgh should
gradually diminish by this afternoon. MVFR cigs may briefly
build back across the area near 12z, but full return to VFR is
expected this afternoon with drier and and backing flow.

Westerly winds remain breezy through the day, with gusts as
high as 25-30 knots at most terminals.

Outlook...
Restriction potential returns Wednesday, especially north of
Pittsburgh, as rain and snow showers develop under another
crossing trough. VFR returns Thursday and Friday under high
pressure.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Lake Effect Snow Warning until 1 PM EST this afternoon for
     PAZ007-008.
     Winter Weather Advisory until 1 PM EST this afternoon for
     PAZ009-074-076.
OH...None.
WV...Winter Weather Advisory until 1 PM EST this afternoon for
     WVZ510>512.
     Winter Storm Warning until 1 PM EST this afternoon for WVZ513-
     514.

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB/Lupo
SHORT TERM...MLB
LONG TERM...AK
AVIATION...Rackley