- A stormy pattern is setting up for the West and Plains beginning Sunday.
- Two rounds of severe thunderstorms are possible in the Plains.
- Snow, heavy in spots, is expected in the Rockies.
A strong fall storm is expected to develop next week and could ignite severe thunderstorms in the Plains, strong winds, soaking rain, and the most widespread snow of the season in the Rockies.
After recent events were centered around flooding, tropical storms and hurricanes, excessive heat, wildfires and drought, the atmosphere is delivering an altogether different pattern into mid-October.
Two southward plunges of the jet stream will push into the West. The first will swing through the next few days; A second, more powerful jet plunge will carve southward out of western Canada into the West beginning Sunday.
The second jet plunge will spin up a strong low-pressure system over the Plains by the middle of next week. That storm will have a mix of weather impacts, from severe thunderstorms and soaking rain to strong winds and snow.
Forecast jet stream pattern Sunday through Wednesday.
Severe Weather Threats
Two rounds of severe thunderstorms – one associated with each jet stream plunge mentioned above – are possible in the central U.S.
The first round Sunday afternoon and evening could affect parts of Oklahoma, northern Texas and southern Kansas, then could trigger additional strong to severe thunderstorms Monday a bit farther east into the mid-Mississippi Valley.
The second round of severe thunderstorms is possible Tuesday into Wednesday in parts of the Plains and possibly as far east as the Mississippi Valley.
Typical for severe thunderstorm forecasts, there remains considerable uncertainty this far out in time. Precise timing, locations of peak threat and the magnitude of the severe threat are all key questions that will be answered in the coming days.
(MORE: Fall Can Be a Secondary Peak For Tornadoes)
For now, NOAA’s Storm Prediction Center has highlighted parts of the Plains they are most confident of at least some threat for severe weather early next week in the graphics below.
First Snow For Some, Heavy Snow For a Few
The first jet plunge will wring out mainly light snow over the higher peaks of the Sierra and northern Rockies through Saturday.
The second, stronger jet plunge will have colder air to work with and, therefore, produce the most widespread snow of the season so far in the West.
(MAPS: 10-Day U.S. Forecast Highs and Lows)
Snow is expected to intensify and spread through the northern Rockies and Wasatch through Monday into the mountains of Colorado and High Plains of Montana, Wyoming and perhaps even parts of the western Dakotas and western Nebraska Tuesday into Wednesday.
Some of the highest elevations could pick up over a foot of snow. Some lower elevations could receive the first accumulating snow of the season, including Billings, Montana; Casper, Wyoming; the “benches” east of downtown Salt Lake City; and some foothills to the west of the Fort Collins-Boulder-Denver Front Range urban corridor.
This could make for slippery travel over mountain passes and higher elevations, including interstates 15, 25, 70, 80 and 90. Strong winds Tuesday into Wednesday in parts of the High Plains could combine with snow to yield reduced visibility in spots.
Rain and Snow Outlook
(While it is too far out in time to specify exact forecast snowfall totals, areas in the purple and pink contours have the highest chance at heavy snowfall.)
Where it will be too warm to snow, soaking rain – while a hindrance at harvest time – will be of some relief for both the long-term, widespread drought in the Northern Plains and the rapidly developing “flash drought” in Oklahoma and parts of Texas.
Check back frequently for updates to this forecast in the days ahead.
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