TL;DR

The NOAA Storm Prediction Center (SPC) has issued a Marginal Risk for severe thunderstorms today across the central Plains and the Great Basin. Isolated damaging winds and hail are possible this afternoon into tonight, with the best chances across eastern Colorado into Nebraska, and parts of Utah. No tornado activity is expected.

What's Driving Today's Weather?

Monday's severe weather setup is driven by three separate features spread across the central and northern United States. None are particularly strong, which is why SPC has kept the risk at Marginal — the lowest category on the five-tier scale.

Over the central Plains, a persistent plume of mid-level moisture continues to affect areas from Arizona into Colorado. An afternoon round of thunderstorms is expected over the mountains, with storms spreading eastward into the plains by evening.

In the Great Basin, a shortwave trough over California will track eastward and provide large-scale forcing for ascent across Utah and northern Arizona. Scattered thunderstorms are expected once again this afternoon.

Where Is the Marginal Risk Today?

The Marginal Risk area covers two distinct regions:

  • Central Plains: Eastern Colorado and much of Nebraska
  • Great Basin: Much of Utah and northern Arizona

These areas represent where isolated severe storms are most likely, though the overall coverage will remain low. Most locations within the Marginal Risk area will not see severe weather.

Timing and Hazards

Eastern Colorado into Nebraska

Mountain thunderstorms will develop during the afternoon over the Colorado Rockies, then spread eastward into the plains. Strong outflow winds may accompany the more intense cores as they move into eastern Colorado. Isolated strong storms may persist into parts of Nebraska after dark.

Primary hazards: Damaging outflow winds, with gusts potentially exceeding 60 mph in the strongest cells.

Peak timing: Late afternoon into evening for Colorado; evening into overnight for Nebraska.

Utah and Arizona

Scattered thunderstorms will develop this afternoon across much of Utah and northern Arizona as the shortwave trough moves through. If pockets of sufficient heating can develop ahead of the storms, locally damaging wind gusts could occur.

Primary hazards: Isolated damaging winds.

Peak timing: Afternoon through early evening.

Yesterday's Severe Weather

Sunday brought another active day of severe weather across the northern Plains and Rockies, continuing a pattern that has dominated the last week. The SPC received 112 wind reports and 1 hail report across Colorado, Kansas, Montana, North Dakota, South Dakota, Utah, and Wyoming.

The most significant event occurred in Buffalo, South Dakota, where winds estimated at 100 mph caused significant tree damage, blew shingles off house roofs, and damaged buildings due to falling trees. Several other locations in South Dakota and Wyoming recorded wind gusts between 70 and 85 mph.

No tornadoes were reported yesterday, marking the second consecutive day without tornado activity across the United States.

What About Tomorrow?

SPC's Day 2 outlook upgrades the risk to Slight for portions of the central Plains and Midwest on Tuesday, September 1. A more organized severe weather event appears possible as a stronger disturbance moves through the region. The Slight Risk area is expected to cover parts of Nebraska, Kansas, and surrounding states.

The Day 3 outlook maintains a Slight Risk for Wednesday across the Great Lakes and Southeast as the system continues eastward.

Stay tuned to VORTEX for updates as the forecast evolves.

Staying Alert During Overnight Severe Weather

Today's storms across the central Plains will continue well into the overnight hours, when many people are asleep. Third-party weather apps are silenced by Do Not Disturb, though Wireless Emergency Alerts for tornado warnings still break through on most phones. For those who want an extra layer of protection for non-tornado severe weather, or who care about locations beyond their immediate area, a phone call can provide the alert that wakes you up.

VORTEX is a free web app at vortexintel.app that monitors severe weather nationwide. Pro ($4.99/month) places phone calls to your phone when a tornado or flash flood warning is issued for a location you care about — calls can ring through Do Not Disturb once you enable Emergency Bypass for the number, unlike most third-party app notifications.