Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
246 AM EST Sat Dec 25 2021

Valid 12Z Sat Dec 25 2021 - 12Z Mon Dec 27 2021

...Significant mountain snowfall, travel disruptive lowland snow, and rain
through the Holiday Weekend for the West...

...Anomalously warm temperatures continue for most of the central and
eastern U.S., with record highs possible from the Southern Plains to
Mid-Atlantic...

...Scattered rain showers and a wintry mix forecast in the Northeast
Christmas Day; new winter storm to develop in the Upper Midwest Sunday
night...

The seemingly endless upper level troughing pattern in the West is
forecast to stick around through Christmas and the remainder of the
holiday weekend. Anomalously cold conditions and a barrage of Pacific
moisture results in prolonged periods of mountain snow and coastal/valley
rain, some of which may fall heavy at times. Enough cold air is in place
for even metropolitan areas of the Northwest to receive measurable
snowfall. Winter Storm Warnings have been issued from Portland, Oregon and
the Willamette Valley on south to the Sierra Nevada and the Transverse
Range in Southern California through Sunday. Through the remainder of the
weekend, the heaviest snowfall totals are expected to occur in the
northern and central Sierras with 2 to 4 feet of snow (locally higher
amounts possible) are expected. The Portland metro area may receive a 2 to
5 inches of snow and the Seattle metro (under a Winter Weather Advisory
through Sunday afternoon) could witness as much a few inches of snow. A
little father east, after snow winds down this morning and a brief break
in the active weather pattern arrives Christmas afternoon, the next upper
level disturbance slams into the West Coast on Sunday, delivering another
round of moderate-to-heavy snowfall to the Intermountain West. Snow
totals, from the Sawtooths, the Tetons, Wasatch, and central Rockies can
anticipate roughly 1 to 2 feet of snow by the end of the weekend. Travel
will be treacherous, to at time impossible, from the Sierras to the
central Rockies this weekend due to whiteout conditions and drifting snow.

The other "hot" weather story of the weekend will be the continued much
above normal warmth for most of the central and eastern U.S. Record-tying
and record-breaking high temperatures are likely from the Southern Plains
to the Mid-Atlantic. The warmest average temperatures for Christmas Day
will stretch from the heart of Texas to the Middle Mississippi Valley,
Ohio Valley, and Mid-Atlantic where temperature departures look to range
between 25 to 35 degrees above normal. A passing cold front drops
temperatures to more seasonally warm levels in the Ohio Valley on Sunday,
but much of the South remains remarkably warm as highs soar into the 80s
once again in Texas and Oklahoma. Winds will also increase ahead of a cold
front across the High Plains on Sunday. The combination of windy, dry, and
continued warm conditions have resulted in a Critical Risk of fire weather
issued by the Storm Prediction Center for southwest Kansas and both the
Oklahoma and northern Texas Panhandles. One exception to the anomalous
warmth (aside from the cooler, stormy setup along the West Coast) is the
Northern Plains where frigid Canadian air will pool 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.

Elsewhere, scattered light to moderate rain showers along a frontal system
will move across the Northeast and Ohio Valley Christmas Day. A wintry mix
of freezing rain and snow is forecast in the cooler air on the north side
of the front across upstate New York and New England. A glaze of freezing
rain is expected for Upstate New York and western New England, with
accumulations of around a tenth of an inch possible in the Hudson and
Connecticut River Valleys. Snow showers are likely for the higher terrain
of western New England and Maine. Winter Weather Advisories have been
issued for these areas through Christmas morning. By Sunday afternoon,
snow will begin to increase in coverage across the Northern Plains and
Upper Midwest as an emerging storm system strengthens and approaches from
the West. Latest forecast guidance indicated anywhere from 6 to 12 inches
of snow is possible in eastern North Dakota Sunday night and into early
Monday morning. Parts of northern Minnesota may also pick up as much as 6
inches Sunday night. A glaze of ice accumulation is also possible in the
Upper Mississippi Valley and the central Great Lakes Sunday night into
early Monday morning.

Mullinax


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