937
FXUS61 KPBZ 071821
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
121 PM EST Sun Dec 7 2025

.SYNOPSIS...
Light snow accumulation expected on Sunday primarily north and
east of Pittsburgh. Continued rounds of rain and snow chances
will prevail through next week with increasing wind Tuesday and
Wednesday.

&&

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

- Light snow today with up to an inch along and north of I-80,
  little to no accumulation elsewhere
- Cold overnight lows in the teens
---------------------------------------------------------------

A flat mid-level shortwave will traverse the Great Lakes region this
afternoon as a surface cold front slowly sags through the area NW to
SE. Both features will bring with them the chance for light snow
showers today, highest north of Pittsburgh.

Fairly uniform WSW flow through the column hasn`t done much for deep
layer moisture return and saturation with latest rounds of ACARS
soundings from PIT depicting a dry layer from 850 to 600 mb and a
sharp inversion situated at the bottom of that layer. This will
limit the overall snowfall totals and rates today, as will weak
forcing associated with the zonal shortwave and unfavorable exit
region dynamics from a mid-level jet. Latest model runs have
continued the downward trend in snow totals which makes sense given
the environment. Across the lowlands south of I-80, some light snow
showers (perhaps a mix with rain given marginally cold temperature
profiles) are possible as potential seeder-feeder effects can
saturate the dry layer enough, but with little to no accumulation.
Along and north of I-80 is where the "higher" snowfall amounts will
be as moisture is a bit better and closer proximity to the shortwave
and front overlap aids in forcing. 12z HREF probability for
measurable snow is 70-90% along and north of 80 as well as in the PA
ridges, but sharply drops off to <20% farther south and in the
lowlands. Bumping up to a half an inch shows <10% for our entire
area, even after increasing the neighborhood radius to account for
spatial uncertainty. So, most will see perhaps a dusting while the
higher elevations and I-80 corridor could see up to a half an inch
at most.

Surface high pressure quickly builds in the wake of the frontal
passage and ushers in a colder airmass from Canada. Dew points tank
into the low teens/single digits overnight thus lowering the
potential floor for radiational cooling, but it appears that enough
of a northerly flow and slow to clear cloud cover is going to offset
it. Still, lows will dip into the teens for most and single digits
north of I-80.

&&

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

- Dry and cold Monday under high pressure
- Another light snow north of Pittsburgh Tuesday
----------------------------------------------------------------

Surface high pressure will cross the region Monday, which will
yield light winds, but also well below normal temperatures as
the cP airmass transitions over the forecast area. Although
daytime max temperatures will be 15-20 degrees below normal on
average across the region,m for perspective, they will still be
10 to 15 degrees warmer than current low max records. Expect
highs between 20 to upper 20s.

A shortwave within the relatively zonal flow crosses the Great
Lakes on Tuesday, returning a slight chance of snow north of PGH
during the day associated with a weak surface low.

Thermal profiles look to support a melting snowfall as modest
WAA supports daytime highs in the mid 30s across much of the
region. Accumulations on roadways look unlikely from this
system.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:

- Below normal temperatures continue through the long term.
- Additional rounds of potential winter weather with a series
  of passing disturbances mid and late week.
-------------------------------------------------------------------

Upper troughing will continue to be the dominant feature the
second half of the upcoming week, which will maintain the
relatively active pattern. Continued WAA across the region
leaves overnight lows near that freezing mark but supports
daytime highs climbing into the low 40s on Wednesday. As such
the next system looks to be more of a rain/snow mix, with snow
most likely across the ridges and north of I-80 and rain favored
elsewhere. Accumulations of snow, most likely in the PA/WV
ridges and north of I-80, would wind down through the day as
temperatures climb and many areas turn over to rain. The cold
front sweeps the region late Wednesday turning remaining
precipitation back to snow. QPF estimates from this system
remain near 0.25 inches.

POPs lower slightly across the lowlands on Thursday favoring a
brief stint of lake enhancement and upslope flow on the heels of
the Wednesday system. Once again, timing uncertainties in the
departure of the midweek system and the arrival of the late week
system are spreading POPs widely across Thursday, but some stay
of dry weather is expected during this time frame.

Yet another clipper looks to sweep the Upper Midwest and Ohio
Valley during the Thursday night/Friday time frame. The exact
track of this system will determine what kind and how much
precipitation we can squeeze out. At this time, ensembles are
rather spread on their depictions of this track, but a more
southern track would give us a better chance of seeing impactful
winter weather. A more northern track would favor a rain/snow
mix with the best snow in the ridges and north of I-80, similar
to Wednesday.

Temperatures in the extended period look to fluctuate some but
with the trough advancing into the region, generally trend down
as we head towards the weekend. Differing depictions of the
depth of the trough as it moves overhead lead to a wide spread
in temperatures for next weekend but ensembles that favor a
deeper trough feature another shot of very cold air.

&&


.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Prevailing MVFR ceilings are ongoing and expected to continue
through tonight. Light snow will impact primarily the northern
part of our area and with highest confidence at FKL/DUJ.
Confidence in any snow (and associated worsening restrictions)
drops the farther south you go. With probabilities of any
precipitation only ~20% at ZZV and MGW, no snow was noted at
those locations for now. Elsewhere, a mix of PROB30s to the
south (lower confidence) and TEMPOs to the north (higher
confidence) have been maintained to reflect estimated onset/end
times and reductions to visibility.

Snow tapers overnight as a weak cold front moves through and
light west winds shift to more northwesterly or northerly under
building high pressure. MVFR ceilings will continue following
the frontal passage with indication that a brief period of IFR
could be possible within the post-frontal cold advection regime.
Have trended ceilings a bit more pessimistic but haven`t locked
in prevailing IFR with this update as guidance continues to
bounce around and the majority of upstream observations are
hanging on to low MVFR conditions.

Expect that VFR will gradually work its way back in as drier
air intrudes in the latter half of the overnight hours. Wind
will hold out of the northeast into the day on Monday with dry
conditions.

Outlook...
The overall weather pattern through the week strongly favors
shortwave movement within upper troughing that brings
precipitation and restriction potential to the area generally
every other day. Precipitation chances remain largely in the
form of snow, save for short periods of rain at southern
terminals during daytime hours. Wind looks to increase on
Tuesday and especially Wednesday with passing low pressure.

&&

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

&&

$$

SYNOPSIS...MLB/AK
NEAR TERM...MLB
SHORT TERM...88/AK
LONG TERM...88/AK
AVIATION...MLB