Enhanced Risk in Effect Across Two Regions
The NOAA Storm Prediction Center (SPC) has issued an Enhanced Risk—level 3 of 5—for severe thunderstorms across two distinct areas today, April 17, 2026. The first zone stretches from the Upper and Mid Mississippi Valley, while the second covers Kansas and Oklahoma eastward into the lower Missouri Valley.
According to the SPC Day 1 Convective Outlook issued at 0739 AM CDT, "numerous severe thunderstorms are likely this afternoon into tonight across parts of the Upper Midwest southward across the lower Missouri Valley into central Great Plains." The outlook warns that storms may initially produce large to giant hail and a few strong tornadoes before severe wind gusts of 60 to 90 mph become the dominant hazard this evening.
This is an active and evolving severe weather situation. Residents across the Enhanced Risk area should have multiple ways to receive warnings today and tonight.
What's Driving Today's Severe Weather
A surface low pressure system near the Nebraska-Iowa-South Dakota border is the focal point for today's severe weather. A cold front extends southwestward from this low into the central High Plains, while a warm front is lifting northward across Iowa into the western Great Lakes.
Upper-level dynamics are equally impressive. Water vapor imagery shows a prominent upper trough near the Montana-North Dakota border extending south into eastern Utah. A belt of increasingly strong southwesterly 500-millibar flow will overspread the destabilizing warm sector as the trough reaches the Upper Midwest and central Plains late tonight.
The combination of strong wind shear, abundant atmospheric moisture, and steep mid-level lapse rates will create an environment highly favorable for organized severe thunderstorms, including supercells.
Upper and Mid Mississippi Valley: All Hazards Possible
The Setup
A northward-expanding warm and moist sector is being fed by a 50-knot-plus southerly low-level jet. Surface dewpoints in the 60s Fahrenheit are being advected northward beneath steep mid-level lapse rates, supporting the development of a moderately to very unstable airmass from Iowa and Illinois northward into the upper Mississippi Valley.
The SPC forecasts "upwards of 1500-3000 J/kg MLCAPE" immediately ahead of the front. This level of instability, combined with strengthening flow aloft, strongly favors organized storms including supercells.
Timing and Hazards
Convection may develop as early as late morning across southern Minnesota, with the large-hail threat beginning during that window. By later this afternoon, discrete supercells are expected to develop ahead of the front over parts of central and northern Wisconsin near the surface low, and farther south in the vicinity of eastern Iowa into adjacent portions of Wisconsin and northwest Illinois.
The SPC notes that "all hazards will be possible with this potential activity, including the possibility for an intense tornado." Large to giant hail will be possible with supercells during the afternoon and early evening.
As storms evolve, a band of severe thunderstorms will likely develop farther west and push eastward along the front. Damaging wind gusts will become more prevalent during the evening hours as storms transition to linear modes. Some tornado risk may continue into the evening as maturing bands of storms produce bowing segments and embedded mesovortices.
This activity is expected to gradually diminish late tonight as it moves east into Indiana and Lower Michigan.
Cities to Watch
- Madison, Wisconsin
- Milwaukee, Wisconsin
- Rockford, Illinois
- Cedar Rapids, Iowa
- Dubuque, Iowa
- La Crosse, Wisconsin
- Green Bay, Wisconsin
Kansas and Oklahoma: Giant Hail and Damaging Winds
The Setup
East of a dryline and cold front, continued moistening and heating will lead to a very unstable airmass from Oklahoma into Kansas by early to mid afternoon. A capping inversion will likely inhibit storm development until mid afternoon near the front, but once storms break the cap, they will tap into significant energy.
The environment features "appreciably large CAPE/shear," according to the SPC, supporting both supercell and quasi-linear convective system (QLCS) tornado risks.
Timing and Hazards
Initial storm development will likely be supercellular near the triple point (where the warm front, cold front, and dryline meet) by mid afternoon. A more extensive band of cellular storms is expected to develop along the boundary shortly thereafter.
Large to giant hail could accompany any mature or sustained supercell, along with a tornado risk. Farther south along the dryline, the setup is more conditional, but any storms that do develop will pose a significant hail and tornado threat.
As individual storm cold pools coalesce, a squall line is expected to intensify with embedded surges and bowing segments. The SPC warns this evolution "may result in focused swaths of more intense severe gusts (i.e., locally 75-90 mph) from south-central and eastern KS into west-central MO."
Eventually the front will sweep southeastward with a convective line yielding a risk for wind and hail into the overnight hours.
Cities to Watch
- Wichita, Kansas
- Topeka, Kansas
- Kansas City, Missouri
- Tulsa, Oklahoma
- Oklahoma City, Oklahoma
- Salina, Kansas
- Manhattan, Kansas
Yesterday's Severe Weather Context
Over the past 24 hours, 23 hail reports and 67 wind reports were logged across the central United States, primarily across Missouri, Kentucky, Tennessee, and surrounding states. The largest hail was 3.00 inches in diameter (baseball-sized) reported at 2 ENE Iberia, Missouri at 1945 UTC.
While yesterday's activity was notable, today's threat is more widespread and intense, with higher instability and stronger shear supporting more organized severe storms.
Safety Actions for Today
Before Storms Arrive
- Identify your safe space now. A basement, interior room, or lowest floor away from windows. If you're in a mobile home, know where the nearest sturdy shelter is located.
- Charge your devices. Power outages are likely with damaging wind gusts forecast up to 90 mph.
- Have multiple ways to receive warnings. Weather radios, smartphone apps, and local media are all important. Note that many smartphone alerts rely on push notifications that are silenced by Do Not Disturb mode at night, though Wireless Emergency Alerts (WEA) for tornado warnings bypass silent mode on most phones by default.
During Severe Weather
- Act immediately on warnings. Tornado warnings and severe thunderstorm warnings mean take shelter now, not in five minutes.
- Do not rely on sirens indoors. Outdoor warning sirens are designed to alert people outside. They are often inaudible inside modern homes.
- Stay away from windows. Giant hail and damaging winds can shatter glass.
The Nighttime Tornado Problem
A significant portion of today's severe weather will occur during the evening and overnight hours as storms push eastward. Nighttime tornadoes are more than twice as deadly as daytime tornadoes, in part because people are asleep and do not receive warnings in time.
Most weather apps rely on push notifications, which are silenced when your phone is in Do Not Disturb mode. If you live in or near the Enhanced Risk area and plan to sleep tonight, consider how you will be alerted if a tornado warning is issued for your location after you've gone to bed.
VORTEX Pro addresses this gap by placing phone calls when a tornado or flash flood warning is issued for a saved location. Phone calls bypass Do Not Disturb mode, ensuring you're woken up even if all other alerts are silenced.
What to Expect Tomorrow
The SPC Day 2 Outlook shows a Slight Risk across portions of Ohio, Pennsylvania, and New York as the system moves eastward. While the threat will be lower than today, scattered severe storms remain possible across the Ohio Valley and interior Northeast on Saturday.
The SPC Day 3 Outlook shows no categorical severe weather risk, indicating the system will weaken as it moves offshore.
Stay Alert
This is a significant severe weather event with threats spanning multiple states and lasting well into tonight. If you are in the Enhanced Risk area, do not wait until storms are visible to take action. Have your plan ready, know where you will shelter, and ensure you can receive warnings even if you're asleep.
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.