Severe weather expected, snow ongoing as classic fall storm system moves East
A storm system that is bringing heavy snowfall to the higher elevations of the West will bring the threat of severe thunderstorms as it begins to emerge from the Rockies and intercepts warm, unstable air over the Plains. The risk for severe thunderstorms will include a fairly broad swath of the nation's midsection Thursday and Friday.
There's also a threat of local flash flooding in parts of Texas, still recovering from last week's destructive flash flooding.
Storm's Wintry Side: Up to 22 Inches of Snow Reported
The storm system that will bring the severe thunderstorm risk east of the Rockies has already brought snow, some of it heavy, to the mountains of the West.
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More than a foot fell in some areas, including northeastern Nevada where 18 inches of snow snapped the branches of fruit trees in Tuscarora on Tuesday.
Snow will expand east across the Rockies into Thursday before tapering off across the northern Plains later in the day. These snows may create difficult driving conditions on Interstate 80 west of Cheyenne, Wyoming, and Interstate 70 west of Denver.
A weaker secondary disturbance will drop through the northern Rockies Thursday night into Friday, bringing lighter snowfall to the mountains of Idaho, Montana and Wyoming.
Severe Weather Forecast
The emerging storm system will bring with it a roaring streak of wind energy several thousand feet aloft. By Thursday, winds some 20,000 feet above ground level will be screaming from the southwest at 100 to 140 mph from the Texas Panhandle to Minnesota. Winds of 60 mph may be blowing just a few thousand feet above ground level in parts of that corridor. Similar conditions will shift into the Great Lakes region Friday.
That's not just a concern for pilots. As thunderstorms erupt, they could pull some of that wind momentum down to ground level and that would bring the potential for damaging winds. That's the main reason for the severe weather threat areas depicted for Thursday and Friday.
The key question is how unstable the atmosphere can get and how far north it can do so. It is, after all, November -- and although record-high temperatures have been recorded ahead of the approaching storm system, the atmosphere may not be all that unstable -- because it's also abnormally warm in the upper atmosphere ahead of the storm.
Still, that instability should have enough of a favorable environment to support severe thunderstorms and even a few tornadoes Thursday into Thursday night over the south-central states.
This is a typical situation in cool-season severe thunderstorm threats -- powerful winds aloft and unstable air near the ground, but not lined up over the same location.
Here's how we see this playing out.
- A few strong to severe thunderstorms may develop over central Texas in the morning as the environment becomes increasingly unstable.
- Thunderstorms will be more numerous as the storm system's cold front sweeps into the Plains through the day. Scattered severe thunderstorms are possible from from central and north Texas into central and eastern Oklahoma.
- A risk for a few strong thunderstorms exists further north into eastern Kansas, Missouri and Iowa, although instability will be limited here.
- Thunderstorms, some severe, may sweep into the mid-Mississippi Valley, Ozarks and east Texas Thursday night.
- The main threats are damaging wind gusts and a few tornadoes, likely to be brief and embedded within lines of thunderstorms.
- Flash flooding is also a threat, though not as large a threat as this past weekend. Flood watches have been posted already in parts of the southern Plains.
- Severe thunderstorms are possible from the eastern Great Lakes to the Lower Mississippi Valley.
- Though the areal coverage of severe storms is likely to be less than Thursday, high wind gusts are possible especially in the northern part of the severe risk area, while an isolated tornado can't be ruled out in the southern part of the risk area.
- Given the limited instability, northern parts of the risk area may experience little or no lightning and thunder but still see damaging wind gusts.
- As the frontal system stalls out, clusters of thunderstorms with locally heavy rain may trigger flash flooding into Friday night from the Tennessee Valley southwestward into the Lower Mississippi Valley and parts of Texas.
The current radar map below focuses on the most likely areas for severe weather and/or flash flooding, if any.
For radar and watch/warning information in other areas of the country, click on the links below.
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