Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
258 AM EST Sun Dec 26 2021

Valid 12Z Sun Dec 26 2021 - 12Z Tue Dec 28 2021

...Significant snowfall for portions of West Coast mountain ranges;
freezing rain threat for parts of interior Northeast tonight into Sunday
morning...

...Anomalously warm temperatures continue for most of the central and
eastern U.S. while cold airmass expands across Northwest; records
possible...

...Dynamic system to bring rain, snow and a wintry mix from the Northern
Plains to the Mid-Atlantic Sunday...

The stagnant upper level jet stream pattern resulting in troughing in the
West and ridging in the South looks to stick around to close out the
holiday weekend and kickoff the final week of 2021. The most impactful
weather remains out West as a pair of storm systems emerge from the
Rockies and eventually become disruptive winter storms in the Upper
Midwest. A steady barrage of Pacific moisture and anomalously cold
temperatures within the atmospheric column support heavy snowfall rats
that will blanket the mountain ranges of the West; from the Sierra Nevada
to the central Rockies, the former of which is forecast to receive the
heaviest snowfall totals through the next couple days. The Sierra Nevada
have already picked up copious amounts of snow in recent days, and yet
another astonishing 2 to 5 feet of snow is forecast through early Tuesday
morning. Meanwhile, other ranges such as the Shasta, the Oregon Cascades,
the Wasatch, Tetons, and Colorado Rockies can expect anywhere from 1 to 3
feet of snow. Hazardous travel conditions are expected across these
ranges, prompting the issuance of Winter Storm Warnings that extend as far
south as the Transverse Range of Southern California. Measurable and
disruptive snowfall accumulations are also on tap in the Pacific
Northwest, including in both the Portland and Seattle metro areas. This
stretch of wintry weather is able to occur thanks to frigid temperatures,
some of which may tie or break record cold highs and lows both today and
Monday.

On the flip side, remarkably warm temperatures remain anchored over the
southern U.S. today and will continue into the first half of the upcoming
week. The mixing of unusually warm temperatures, low humidity levels, and
windy conditions has prompted the Storm Prediction Center to issue a
Critical Risk of fire weather in the central High Plains and both the
Texas and Oklahoma Panhandles. Temperature departures today will be
warmest in the Southern Plains where highs in the 70s and 80s equate to
departures of 25 to 40 degrees above normal. The much above normal minimum
temperatures are anticipated throughout the South and into the
Mid-Atlantic today. A passing cold front will cool down part of the
Mid-Atlantic on Monday, but core of the warmest temperature departures (25
to 40 degrees above normal) moves into the Mid-South and Ohio/Tennessee
Valleys. Additional daily record warm lows and highs are expected to be
broken in these regions. The one exception to the anomalous warmth (aside
from the cooler, stormy setup along the West Coast) is the Northern Plains
where frigid Canadian air becomes injected behind a strong cold front.
Morning lows are forecast to be sub-zero in the High Plains of Montana and
North Dakota with daytime highs struggling to get out of the single digits
Sunday. By Monday morning, lows in "Big Sky Country" are forecast to be
bitterly cold, potentially as cold as -15 to -25 degrees.

Elsewhere, the first in a series of storm systems to exit the
Intermountain West is set to produce heavy snow in the Northern Plains and
Upper Midwest Sunday afternoon and into Sunday night. In advance of this
impending winter storm, Winter Storm Watches have been issues for eastern
North Dakota, northern Minnesota, and northwest Wisconsin. Periods of snow
will stick around in the northern Great Lakes on Monday before tapering
off Monday evening. Snow totals through Monday night are likely to range
between 6 to 12 inches with locally higher totals possible, especially in
the Minnesota Arrowhead. This same storm will usher in light snow and
freezing rain accumulations to the northern Mid-Atlantic and interior
Northeast Monday morning. While totals look to be light, slick travel
conditions and delays are possible in these areas on Monday.

Mullinax


Graphics are available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php