TL;DR

The NOAA Storm Prediction Center (SPC) has issued a Slight Risk for southeast Arizona today, where scattered severe thunderstorms capable of producing wind gusts of 60-80 mph are expected during the late afternoon and evening. Isolated severe storms are also possible across the western Carolinas and near the Raton Mesa in New Mexico and the Oklahoma-Texas Panhandles.

What's driving today's severe weather?

A flattened mid- to upper-level ridge over the Desert Southwest is setting the stage for monsoon thunderstorms across southeast Arizona. Strong daytime heating will combine with a seasonably moist airmass to produce moderate instability—forecast soundings show 1000-2000 J/kg of MLCAPE by mid-afternoon.

The key ingredient for damaging winds is the atmospheric profile. Steep lapse rates—the rate at which temperature drops with height—will be present from the surface through the mid-levels. According to the SPC Day 1 outlook, "steep 700-500 mb lapse rates (around 8 deg C/km) atop very steep low-level lapse rates ahead of this activity will support ample evaporative cooling potential with the stronger thunderstorm cores."

In plain English: when rain falls through this dry, unstable air, it evaporates rapidly, cooling the air and creating powerful downdrafts. These microbursts can produce damaging straight-line winds at the surface.

Meanwhile, a mid-level low over northern Georgia will support scattered storm development across the southern Appalachians, with an isolated wind-damage threat developing in the western Carolinas as surface temperatures warm and instability peaks this afternoon.

Where is the highest risk today?

The Slight Risk area covers southeast Arizona, including Tucson and Sierra Vista. This is where the SPC forecasts the greatest concentration of severe wind gusts.

Storms will initially develop over higher terrain during the afternoon, then move west across southeast Arizona during the late afternoon and evening hours. As individual cells congeal into small clusters, the risk for microbursts producing 60-80 mph gusts will increase.

Yesterday's storms in the same region produced significant wind damage.

What about other areas?

Western Carolinas

An isolated severe wind threat exists across the western Carolinas this afternoon. The axis of moderate instability east of the mid-level low over northern Georgia will support scattered thunderstorm development across the southern Appalachians. As low-level lapse rates steepen during peak heating, isolated wind damage is possible.

Raton Mesa and the Panhandles

Near the Raton Mesa in northern New Mexico, a local maximum in buoyancy will support widely scattered storm development by mid- to late afternoon. Some forecast models show this activity moving southeast into parts of the Oklahoma and Texas Panhandles during the early evening, carrying an isolated risk for severe gusts and marginally severe hail.

When will the storms hit?

Southeast Arizona: Storm initiation over higher terrain is expected during the mid-afternoon, with storms moving west across the Slight Risk area during the late afternoon and evening. Peak severe weather potential is expected between roughly 5 PM and 10 PM MST.

Western Carolinas: Scattered convection will develop across the southern Appalachians during the afternoon as surface temperatures warm. The isolated severe wind threat will be highest during the afternoon and early evening.

Raton Mesa region: Storm development is forecast for mid- to late afternoon, with activity potentially moving southeast into the Panhandles during the early evening.

What should you do?

If you're in southeast Arizona or the western Carolinas today:

  • Monitor radar and warnings closely during the afternoon and evening. Conditions can deteriorate rapidly with these types of storms.
  • Secure outdoor items that could become projectiles in high winds—patio furniture, trampolines, and lightweight structures are especially vulnerable.
  • Have multiple ways to receive warnings. Outdoor sirens may not be audible indoors, and third-party weather apps are silenced by Do Not Disturb, though Wireless Emergency Alerts for severe thunderstorm warnings still break through on most phones.
  • If a severe thunderstorm warning is issued for your location, move to an interior room away from windows. Damaging straight-line winds can be just as dangerous as tornadoes.

Microbursts can produce wind damage in a matter of seconds. If you see a thunderstorm approaching and notice a wall of dust or debris at the leading edge, take shelter immediately.

What's next?

SPC's Day 2 outlook shows a Marginal Risk across portions of the Central Plains, Midwest, Southeast, and Northeast on Wednesday, with isolated severe storms possible. No organized severe weather outbreak is expected through the remainder of the week.

Today's Slight Risk is a reminder that severe weather isn't limited to spring or to Tornado Alley. Monsoon season in the Desert Southwest brings its own hazards, and residents should treat severe thunderstorm warnings with the same seriousness as tornado warnings when damaging winds are the primary threat.

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.