Tuesday, December 3, 2013

Winter Storm Cleon

Winter Storm Cleon, the third named winter storm of the 2013-14 season, is already producing areas of heavy snow, and is poised to spread both snow and ice into the South and Midwest over the next few days.
Let's delve into the forecast details, starting with the snow forecast in the Rockies, Great Basin, Cascades and Sierra Nevada.

Snow Forecast: Rockies

Background

Current Radar

Background

Rockies Forecast Snowfall

One area of heavy snow Tuesday night will take aim on a swath from east-central Nevada into Utah (mainly south of Salt Lake City) and into western Colorado and southern Wyoming, before tapering off from west to east Wednesday.
(FORECAST: Wed.)
Up to 2 feet of snowfall is possible over the high country of Colorado, and locally over a foot of fresh powder is expected in the Wasatch of Utah and far southern Wyoming.
Snow accumulations in the Denver area will likely skew very heavily toward the foothills, where amounts could reach a foot. Eastern sections of the metropolitan area, including the airport, will probably see less than 6 inches of snow. The Wednesday morning commute will be heavily impacted by the snow and the plummetingtemperatures. Initially warm ground may melt the first snowflakes but any meltwater on roads will freeze over (unless heavily treated) as the arctic air invades, sending temperatures toward the 10-degree mark Wednesday morning after highs in the 50s Tuesday.
Around Salt Lake City the snow will taper off through Tuesday night. Total accumulations of 2 to 6 inches will be common, but most of that had already fallen by late Tuesday afternoon.
Snow will taper off farther west over the Sierra Nevada Tuesday night.
The snowfall will create significant impacts to travel including...
I-80 over Donner Summit and also into the Reno area, as well as from the Salt Lake Valley into southern Wyoming
I-70 over Vail Pass and the Eisenhower Tunnel and over much of western Colorado and eastern Utah, as far east as the Denver metro

Snow Forecast: Plains/Midwest 

Background

Wednesday Forecast

Wednesday Forecast
Background

Thursday Forecast

Thursday Forecast
Background

Potential Snowfall Totals

Potential Snowfall Totals
Winter Storm Cleon will also lay down a swath of heavy snow from the northern High Plains to the northern Great Lakes through the middle of the week.
Tuesday, a broad area of snow will spread from Montana, northern Wyoming and western South Dakota into the rest of the Dakotas, Minnesota, northern Wisconsin and the Upper Peninsula of Michigan Tuesday night into Wednesday.
As low pressure intensifies in the Upper Midwest Wednesday, snow will also intensify from the eastern Dakotas into Minnesota, northern Wisconsin and the U.P. of Michigan. Blizzard or near-blizzard conditions are possible in some outlying areas of the eastern Dakotas and northern Minnesota from late Tuesday into late Wednesday, though this will depend on the yet-unclear track of the Upper Midwest low pressure system.
(MORE: Blizzard Alley)
As you can see in the snowfall forecast at right, the heaviest snow totals, exceeding one foot, are expected in the Arrowhead of Minnesota and far northwest Wisconsin. An east-west swath of generally six inches or more of snow is expected from eastern Montana into the Dakotas, northern Minnesota, northern Wisconsin and northern Michigan.
(FORECASTS: Grand Forks, N.D. | Duluth, Minn.)
While the heaviest snow is expected to remain north of the Twin Cities, however, accumulating snow is expected, with a north (most) to south (least) gradient in snowfall totals. 
Among the impacted interstates are...
I-94 from the Twin Cities to Billings, Mont.
I-90 from southwest Minnesota to Billings, Mont.
I-35 from the Twin Cities to Duluth
Some patchy light accumulations of freezing rain cannot be ruled out in these areas on the southern edge of the snow swath, from South Dakota to central Wisconsin and parts of Lower Michigan, adding to the difficulty of travel in the area. However, this is not going to be an ice storm for the Upper Midwest. 

Late Week Wintry Mess

Background

Thursday's Forecast

Thursday's Forecast
Background

Friday's Forecast

Friday's Forecast
Background

Potential Ice Zone

Potential Ice Zone
Cleon will have a second chapter late this week.
As the upper level low associated with Winter Storm Cleon moves into Canada late Wednesday, the trailing cold front will continue to drag bitterly cold air southeast. With additional upper-level energy poised to swing out from the Desert Southwest into this cold air, a wintry mess is likely.
At this point, a mix of snow, sleet and freezing rain looks to materialize as soon as Thursday from the central and southern Plains into parts of the mid-Mississippi and Ohio Valleys.
This wintry mess is likely to spread into parts of the eastern Great Lakes and interior Northeast Friday. Some light sleet or freezing rain may persist in parts of the Tennessee Valley into Saturday.
(FORECASTS: Dallas | Little Rock | Cincinnati)
While it is too early to pinpoint exact snow and ice accumulations, here is a preliminary outlook for the second chapter of Cleon later this week:
Snow: Some amounts over six inches possible in the High Plains of eastern New Mexico, southern Colorado, and possibly parts of the panhandles of Oklahoma and Texas. Precipitation may wrap up as moderate or heavy snow over parts of Oklahoma Thursday night into Friday. Totals on the order of a couple of inches are possible from southern Missouri and northern Arkansas northeastward into the mid-Mississippi and Ohio Valleys, and the interior Northeast.
Freezing Rain/Sleet: The potential exists for significant ice accumulation from Oklahoma and north Texas into southern Missouri, Arkansas, west Tennessee, and western Kentucky. Hazardous roads (not just bridges and overpasses), downed tree limbs, and at least some power outages are possible in these areas by Thursday and Friday.

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