TL;DR

The NOAA Storm Prediction Center (SPC) has issued a Slight Risk for severe thunderstorms across portions of west Texas into far southwestern Oklahoma, and separately for parts of Montana. Scattered storms capable of large hail up to 1.5 inches in diameter and severe wind gusts of 60–80 mph are expected this afternoon and evening across west Texas. In Montana, isolated severe storms may produce sporadic large hail and damaging winds through the early evening.

What's driving today's severe weather?

A mid-level low is migrating eastward from the Mojave Desert toward the southern Great Basin, while a 90-knot subtropical jet at 250 millibars over Baja and Sonora, Mexico, will progress eastward into the southern High Plains by this afternoon. The nose of this speed maximum will overspread a moist sector east of a dryline where severe thunderstorm development is forecast later this afternoon and evening.

Farther north, a modestly deepening lee trough will focus storm initiation over the central High Plains. Despite some mid- and high-level clouds, strong heating is forecast this afternoon with erosion of appreciable convective inhibition by mid-afternoon.

A mid-level disturbance currently over central New Mexico will move northeast into western Kansas and the Texas Panhandle by early evening, triggering scattered thunderstorm development near the dryline and lee trough.

Where is the highest risk today?

The SPC Slight Risk area covers portions of west Texas into far southwestern Oklahoma. A second Slight Risk area encompasses parts of Montana.

Cities and metros in or near the west Texas risk area include:

  • Lubbock
  • Midland
  • Odessa
  • Abilene
  • San Angelo
  • Wichita Falls

In Montana, the risk area includes portions of north-central and southwest Montana, though specific metro areas are not within the primary threat zone.

When will the storms hit?

West Texas and Southwest Oklahoma

Scattered thunderstorms are forecast to develop near the dryline and lee trough during the mid to late afternoon. Supercell development appears most likely across west Texas, where forecast hodographs show elongation due to the nose of the upper-level speed maximum and richer moisture sampled by the 12 UTC Del Rio, Texas, radiosonde (17.3 g/kg mean mixing ratio).

Large hail—1.5 inches in diameter—will be possible with the supercells during the afternoon and early evening. The SPC has included 15-percent hail probabilities where supercell development appears greatest.

Severe gusts are forecast to become more prevalent during the evening as mergers and outflow consolidate into a few linear clusters. Severe gusts of 60–80 mph are possible as this activity shifts eastward into the Low Rolling Plains and southwest Oklahoma during the evening.

Through the late evening, isentropic ascent near the terminus of the nocturnal jet may support elevated, loosely organized convection across portions of northwest Oklahoma and western Kansas. Isolated hail and wind may accompany the stronger storms over the central High Plains into central Oklahoma, where storm coverage will probably remain isolated.

Montana

Diurnally-driven orographic ascent within the terrain of northern Idaho and southwest Montana will likely support isolated thunderstorm development by late afternoon, given weak capping and northward advection of steep mid-level lapse rates.

Residual low-level moisture across north-central Montana (dewpoints in the upper 40s to low 50s) coupled with 30–35 knot southerly mid-level flow will likely promote intensification and some degree of organization—possibly into transient supercells and/or organized bands—through the early evening hours. Sporadic large hail and severe gusts appear possible with the most intense convection as it spreads north toward the Canadian border.

What happened yesterday?

The past 24 hours saw 16 hail reports and 34 wind reports across multiple states. No tornadoes were reported.

Hail reports were scattered across the Intermountain West and southern High Plains, with the largest hailstone—1.5 inches in diameter—reported in the region.

Wind reports were concentrated in the western states, where a strong outflow boundary brought wind gusts of 61–72 mph to the Boise metropolitan area, along with blowing dust and visibility reduced to less than 100 feet. Roughly 15,000 customers lost power in Ada County, Idaho. Downed trees and structural damage to outdoor market stalls were reported in Kuna, Idaho. In Moses Lake, Washington, a personal weather station measured a 74 mph gust, and a large poplar tree was snapped.

What to expect in the coming days

The SPC Day 2 outlook (valid Saturday, May 30) maintains a Slight Risk across portions of Oklahoma, Texas, Kansas, Nebraska, South Dakota, Colorado, Wyoming, and Montana. Scattered severe storms remain possible across the central Plains and northern Rockies.

The Day 3 outlook (valid Sunday, May 31) shows a Marginal Risk across Kansas, Nebraska, and South Dakota as the pattern shifts eastward.

If you live in or will be traveling through west Texas, southwestern Oklahoma, or north-central Montana today, monitor radar closely this afternoon and evening. Have multiple ways to receive warnings, and know where you'll shelter if a severe thunderstorm warning is issued for your location.

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.