152
FXUS61 KPBZ 132338
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
638 PM EST Sat Dec 13 2025

.SYNOPSIS...
Widespread snow continues this evening into early Sunday. The
highest accumulation is expected south of Pittsburgh and in the
higher elevations. Lake effect snow showers will linger into
Monday. Very cold temperatures are expected Sunday and Monday
before a warm up next week.

&&

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

- Widespread snow tonight into early Sunday morning
- Lake effect snow bands expected Monday
- Cold Weather Advisory Sunday/Sunday night for east Tucker
-----------------------------------------------------------

Evening Update: Passing snow bands observed on radar
reflectivity near Jefferson and Harrison counties in Ohio
prompted the extension of the Winter Storm Warning to include
these areas. No other changes were made to the winter weather
headlines.

Previous Discussion:

Confidence in 6+ inches of snowfall has increased along a line
roughly from Muskingum (Zanesville) through Allegheny
(Pittsburgh) that has prompted an upgrade to Winter Storm
Warning for those areas. Likewise, confidence in 6+ inches of
snowfall, especially lake effect snowfall in bands on Sunday,
has prompted an upgrade to Lake Effect Warning for Mercer and
Venango counties. All other hazards and impacts remain similar
to previous forecasts.

The near term involves two sources for impactful snow across the
region. The first is a clipper that will cross the Ohio Valley
today into tonight, bringing widespread snowfall and highest
amounts south of Pittsburgh and in the Laurels/Allegheny Mtns.
The second is banded lake effect snow taking over early Sunday in
cold northwesterly flow off the lake, lingering into early
Monday. The combination will bring impactful snow to the entire
region, though some will see higher impacts than others.

Snow has already begun across central/eastern Ohio early this
afternoon, though this has generally been light. Better
accumulation rates and moderate to heavy snowfall is expected
later this afternoon and evening, continuing through roughly
midnight, with strengthening mid-level frontogenesis across the
I-70 corridor. Heaviest snowfall will be south of Pittsburgh and
across the Laurels/Allegheny Mtns. Embedded bands of snow will
create hazardous travel conditions with reduced visibility and
rates of 0.5 to 1 inch per hour, also locally enhancing snowfall
totals.

Totals for the Pittsburgh metro range from 4-5" in
northern Allegheny/southern Butler up to 6-7" across southern
Allegheny into western Westmoreland county. A widespread 5-8"
inches is expected for lowland areas inside the Winter Storm
Warning, with a fairly consistent 8-12" for the
Laurels/Allegheny Mtns. Lake effect snow banding Sunday/Sunday
night will vary over time, but latest CAMs continue to
concentrate the axis across Mercer/Venango counties where 6-8
inches is possible in some areas. Better lake effect
accumulation may extend farther south, but confidence in this is
low.

There is high confidence in all snow for this event, given the
cold profiles and saturated, deep DGZ. Snow to liquid ratios
are expected to be near 20:1 tonight and Sunday, making for a
very dry, powdery snow. One minor concern: initial snowfall
today may melt on surfaces hovering just above freezing. This
will quickly freeze tonight as temperatures plunge.

This provides a segue into the last hazard: cold temperatures.
Temps will drop off quickly tonight, falling into the teens and
single digits by sunrise Sunday. With only ~10 degree warmup by
Sunday afternoon, highs will struggle to make it out of the
teens in most locations on Sunday. This, combined with gusty
winds to around 30 mph will create very cold single and negative
single digit wind chills tonight through early Monday. A Cold
Weather Advisory is in effect for eastern Tucker through Monday
morning where wind chills of -15 to -20F are expected.

&&

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

- Cold Weather Advisory expires Monday morning.
- Cold continues Monday with some snow chances.
----------------------------------------------------------------

The cold weather advisory is set to expire for eastern Tucker
County by 9am Mon day, but that does not mean the cold air is
going anywhere. Monday high temperatures are still forecast to
be around 20 degrees below December normals with wind chills
rising from near zero in the morning to the upper single digits
and lower teens in the afternoon. Chances of any additional cold
weather headlines are reduced overnight with lows a tad warmer
overnight Monday south of I-70.

There is a chance for a clipper system riding the upwind side
of an upper trough and diving across the area Sunday, through
snowfall chances remain low at this time across our forecast
area. There is currently a 75% chance of no accumulations, and
high end totals of a coating to an inch northeast of Pittsburgh
(and the ridges) are possible on the high end.

Tuesday, upper ridging ensues, bring most locations around 10
degrees warmer than the day prior, but temperatures are still
forecast to remain below average. Tuesday is highly confident to
remain dry.

&&

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

- Warming trend through mid-week; quick cold-shot on Friday.
- Rain chances increase late week through the long term.

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

Continued east coast ridging is forecast with high confidence
through Thursday, with small temperature uncertainty. Highs are
expected to near normal on Wednesday with temperatures up to 10
degrees above average on Thursday. This will be accompanied by
increased rain chances in the warm sector of an approaching low.
For now, QPF variability is between a few hundredths and a half
an inch, so no notable impacts at this time.

Forecast confidence begins to break down into Friday with
slight amplitude differences in a quick-hitting eastern trough
behind the passing low. In the event of a stronger trough and
deeper low, temperatures around 10 to 15 degrees below average
and lake-effect snow is possible Friday, but in the more likely
event of a weaker trough, temperatures could fall slightly below
normal with lower lake-effect chances.

By late week, all clusters indicate a relaxation to quasi-zonal
flow with slight 500mb height uncertainties likely resulting
from weak longwave troughs/ridges and quick hitting shortwaves.
This pattern generally favors near to above average temperatures
and perhaps higher chances of precipitation than normal through
Christmas.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:

- Widespread snow with LIFR to continue through the evening
  hours
- Heaviest snow to largely wind down by 06z
------------------------------------------------------------

The TAF period begins with widespread LIFR with a few pockets
of IFR. Much of this is driven by VIS reductions in widespread
snow. Snow is expected to pick up in intensity here shortly and
remain at its heaviest through around 06z. This has been carried
in TEMPO groups at many ports. Widespread snow begins to taper
some between 06-10z from W to E becoming more showery in nature.
Snow will continue as VCSH for many lowland ports but has been
continued as -SHSN for FKL and DUJ as lake effect begins to
pick up on the coattails of synoptic snow.

CIGs are largely OVC at low end MVFR but broken down into IFR
territory in pushes of heavier snow. This is expected to
continue until we see snow begin to taper, when MVFR CIGs are
expected to become more the rule rather than the exception.

Peak snowfall rates for terminals near and south of KPIT look
to be between 0.5" and 1.0" per hour through roughly 1am.
Additionally, gusty W-WSW wind will increase with gusts around
20kts behind the front. Gradual improvement is expected Sunday
morning, but restrictions and scattered snow showers and lake
effect banding will continue through Monday morning in cold NW
flow.

Outlook... General VFR should return by late Monday through
Wednesday as high pressure briefly builds in..

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 1 PM EST Sunday for PAZ013-014-
     020-022-077.
     Winter Storm Warning until 1 PM EST Sunday for PAZ021-029-031-
     073>076-078.
     Lake Effect Snow Warning until 7 AM EST Monday for PAZ007-008.
     Winter Weather Advisory until 7 AM EST Monday for PAZ009-015-
     016.
OH...Winter Weather Advisory until 1 PM EST Sunday for OHZ039>041-
     048.
     Winter Storm Warning until 1 PM EST Sunday for OHZ049-050-
     057>059-068-069.
WV...Winter Weather Advisory until 1 PM EST Sunday for WVZ001.
     Winter Storm Warning until 1 PM EST Sunday for WVZ002>004-012-
     021-509>514.
     Cold Weather Advisory from 7 AM Sunday to 9 AM EST Monday for
     WVZ514.

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan/Rackley
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...AK