FOUS11 KWBC 240838
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
338 AM EST Sat Jan 24 2026

Valid 12Z Sat Jan 24 2026 - 12Z Tue Jan 27 2026

...Ongoing major winter storm to bring the potential for crippling
icing, significant sleet, and heavy snow from the Southern
Rockies/Plains through the Southeast and up the Atlantic Coast into New England...

Meteorological Overview...

Forecast remains on track as a massive winter storm, set to
produce a swath of heavy snow and dangerous ice accumulations, has
begun across the southern Rockies and Plains as tropical East
Pacific moisture streams out ahead of the 500mb closed low near the
Baja Peninsula. This moisture plume is clashing with the coldest
air- mass of the season, entrenching itself over the Nation's
Heartland. The moisture transport is exceptional with an integrated
vapor transport (IVT) above the 97.5 climatological percentile per
ECMWF SATs. The rich moisture from the south will accompany strong
850-700mb WAA that results in classic over-runing along an area of
850-700mb FGEN stretching from atop the Southern Plains to the TN
VLY and southern Mid-Atlantic by tonight. Meanwhile, the upper
trough in the Southwest and an emerging upper- level shortwave
trough over the Dakotas will strengthen a zonally oriented 250mb
jet streak over the east- central U.S., placing its thermally-
direct right- entrance region over the Southern Plains and Mid-
South. This synoptic- scale setup helps to enhance the mesoscale
below, fostering heavy bands of snow and even elevated instability
above the low-level sub- freezing layer over north TX on east into
the Mid-South today.

As the upper low near Baja approaches Texas by tonight, its
associated jet streak over Mexico will co-locate its divergent
left-exit region over the southern Plains and Mid-South, maximizing
upper- level ascent over the region. The IVT in advance of the
upper trough over Mexico is both expansive and strong with >90th
climatological percentile IVT values originating south of Mexico
and extending all the way to the Southern Appalachians by Saturday
afternoon. The remarkable extent of the IVT and the slow
progression of the Mexico trough is why parts of the South and Mid-
Atlantic are likely to see snow, sleet, and freezing rain for over
24 hours and in some cases approaching 48 hours. As arctic high
pressure slides east, a substantial cold- air damming (CAD)
signature will become well pronounced along and east of the
Appalachians as anomalous Pacific and Gulf moisture arrives,
leading to precipitation falling into the frigid air-mass and
supporting heavy snow, sleet, and freezing rain totals from the
southern Appalachians to the Mid-Atlantic.

Saturday night (tonight) into Sunday is when this event truly
starts to peak in expansiveness and magnitude with wintry
precipitation continuously spanning from New Mexico to the
Northeast. Given the event is now well within the short range and
the synoptic pattern is locked into place, uncertainty now mostly
lies within the thermodynamics and both the depth as well as
latitudinal reach of the mid-level warm nose. Depending on which
CAM or global guidance you look at, this warm nose still has about
100 miles of uncertainty. This uncertainty is most notable where
WAA is strongest, throughout the Mid-Atlantic and into the
Northeast Saturday night into Sunday. Here, the NAM3k and RRFS
remain the farthest north and GFS/FV3 farthest south. WPC
preference tonight was in the middle, somewhere between the CMC-
Regional and NAM3k with how far north mixing would reach. What all
models do both agree on is by Sunday, a very pronounced area of
strong 700mb Q-vector convergence will unfold along the Mid-
Atlantic coast, prompting the development of a coastal low along a strengthening coastal front. With the benefit of the 250mb jet
streak's divergent right- entrance region aloft and the
strengthening IVT (ECMWF SATs show >99.5 climatological percentile
values over the Southeast Sunday morning), an expansive
precipitation shield will span across the OH Valley, Mid-Atlantic,
and Northeast with excessive amounts of wintry precipitation
falling. While there remains some question on precipitation type,
NBM probabilities for >1.0" of QPF for the this event are greater
than 70% from the Southern Plains to southern New England, implying
a high amount of QPF that will be at this winter storm's disposal.

Heavy Snow/Sleet...

The latest forecast calls an astonishingly long swath (over 2,000
mile long in length) of >6" of snowfall that starts in the Sangre
De Cristo and Sacramento mountains of New Mexico all the way to
Downeast Maine. It is worth noting that the snowfall probabilities
being referenced will have snow and sleet and not include snowfall
already fallen prior to 12Z Saturday (this morning). Focusing on
the Plains first, WPC probabilities sport medium chances (50-70%%)
for snowfall >8" over the TX Panhandle, central OK, southern MO,
and northern AR. There is another impressive swath of high chance
probabilities (>70%) for >8" of snow from southern IL/IN and
north- central KY to eastern Maine. The Central Appalachians,
interior Northeast, and southern New England are likely to see the
most snowfall with high chances (>70%) for over a foot of snow in
these areas. In fact, WPC probabilities show low- to-moderate
chances (30-50%) for totals over 18" in the Catskills, Berkshires,
and eastern MA to the southern coast of ME. Farther south, the
inclusion of sleet from the LI sound southward along the I-95
corridor will likely cut into snowfall totals. Climatologically
speaking, areas west of I-95 where topography increases are most
likely to see more snow than sleet. This is evident in the >8" for
snow and sleet probabilities where they are high (>70% chances)
from northwest VA and north- central MD along Parr's Ridge to the
Lower Susquehanna Valley, but below 50% over southern NJ, the MD
eastern shore, and south of Fredericksburg, VA. Still, the WSO
shows >50% chances for a warning-level snowfall as far south as
central VA on east through the northern DelMarVa and into southern
NJ due to the strong 850-700mb FGEN Saturday night and Sunday
morning that fosters snowfall rates that could ranges between
1-2"/hr just north of the warm nose and changeover to sleet. This
FGEN is so strong in several CAMs as it lifts northward into the
Northeast on Sunday, mostly in part to the extreme thermal
gradient in place, that a few instances of thundersnow shouldn't
be ruled out. Even for areas that don't remain 100 percent snow,
the combination of snow, sleet, and inclusion of some freezing rain
still support significant travel disruptions in these southern areas as well.

The WSSI shows widespread Major Impacts (considerable disruptions
to daily life: dangerous to impossible driving conditions,
widespread closures, and disruptions to infrastructure) from the TX
Panhandle on east to the Ozarks, through the OH Valley, and all the
way to New England. Every major market along the I-95 metropolitan
corridor (Washington D.C. to Boston and even as far north as
Portland, ME) are expecting major impacts due to snow. The
D.C/Baltimore area on north to Philly and NYC are likely to see
some inclusion of sleet, but it will still result in significant
impacts when accounting for heavy snowfall that is expected to
exceed warning criteria (5-6"). Coastal New England, including the
Boston metro region could also see winds increase to near-blizzard
conditions as wind gusts increase to 30-40 mph due to the
strengthening surface low and continued high snowfall rates. A
reminder that bitterly cold temperatures will follow in wake of
this storm Monday and into the middle of the week throughout the
eastern U.S.. The snow/sleet impacts will linger well into next
week with rounds of re-freezing that keeps surfaces icy and
dangerous to both drive and walk on for the foreseeable future.
Those in the path of this storm should follow advice of local officials.

Freezing Rain...

The most lasting and dangerous impact will come as a result of
significant to locally catastrophic ice accumulations due to
prolonged periods of freezing rain. Just like the swath of >6" of
snowfall, the areal coverage of high chances (>50%) in WPC's ice
probabilities exceeding one-quarter inch of ice accumulation is
both impressive and alarming. From east-central TX to southern AR,
northern LA, northern MS, the TN Valley, northern GA, the southern Appalachians, and southern Mid-Atlantic, these regions are all
likely to experience anywhere from one-quarter to one-half inch of
ice. Widespread power outages and tree damage is likely in these
areas, especially from the Lower MS Valley, southern Appalachians,
central NC, and south-central VA, where there are also medium
chances (>50%) for ice accumulations over one-half inch.

It is parts of northwest AL, northern MS, south-central TN,
southeast AR, northern LA, far northern GA, the southern
Appalachians, and the NC Piedmont that are of greatest concern. WPC probabilities show low- to- moderate chances (20-40%) for ice
accumulations over 1 inch and higher probabilities (30-60%) across
parts of northern/northwestern MS. These areas are likely to
endure a crippling ice storm that will take days, if not weeks, of
clean up in addition to extended power outages while bitterly cold
temperatures linger into next week. This is demonstrated in a rare
Extreme Impact on the WSSI in parts of northern MS, northeast LA, and
the Southern Appalachians. The WSSI Extreme criteria references
the potential for "extensive and widespread closures, extremely
dangerous travel, and life- saving actions may be needed." Once
the freezing rain starts, dangerous travel will be common not only
during the event, but in the days in wake of the storm due to
prolonged sub- freezing temperatures that cause persistent re-
freezing on all untreated surfaces. The Key Messages for the
Extreme Cold are linked below (Key Message 1).

Farther east, freezing rain will reach southern VA, the DelMarVa
Peninsula, and as far north as the I-95 corridor from Washington
D.C. to Philadelphia. The southern VA Piedmont, including the
Richmond metro area, have medium chances (40-60%) for over one-
half inch of ice. The WSSI depicts Major Impacts from Richmond on
south along I-95 into NC. While most areas farther north towards
the Lower Delaware Valley, Washington D.C. into southern NJ should
largely remain sleet, it may transition to freezing rain for a
brief time by Sunday evening. WPC probabilities show low-to-
medium chances (30-60%) for over one- tench of an inch of ice
accumulations Sunday evening.

Key Messages for this system are linked below (Key Message 2)

Snell/Mullinax

...Extreme Cold & Winter Storm Key Messages are in effect. Please
see current Key Messages below...

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_2.png

$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (21:1/175)