Severe thunderstorms are expected to impact a large portion of the central United States from Tuesday through Thursday, driven by moisture from Hurricane Simon. The storms threaten six states: Texas, Oklahoma, Kansas, Missouri, Iowa, and Illinois.
The National Weather Service's Storm Prediction Center has placed parts of the central and southern Plains under a "Slight Risk" of severe thunderstorms, the second tier on its five-level scale. This threat is being fueled by the remnants of Hurricane Simon, which is currently in the Pacific Ocean off the coast of Mexico, combining with humid air from the Gulf of Mexico.
A low-pressure system moving east across the Southwest will help lift warm, humid air, while a cold front advances through Kansas. Temperatures climbing into the mid-80s and low 90s are expected to provide additional energy for thunderstorm development. Meteorologists anticipate that a layer of warm air that has been suppressing storm development should weaken during the afternoon, allowing storms to build.
The greatest initial severe weather threat is focused on the Texas and Oklahoma Panhandles, central Kansas, and the lower Missouri Valley. Storms are expected to develop Tuesday afternoon and evening, with the potential for a tornado or two to form in the Plains, particularly near weather fronts where wind conditions favor rotation. In Kansas, the strongest storms could produce hail as large as golf balls before merging into clusters capable of delivering wind gusts of 50 to 65 mph.
Rainfall of 1 to 2 inches is forecast from southwestern Texas into eastern Kansas and western Missouri by Wednesday morning, with localized totals potentially exceeding 3 inches. Repeated downpours could increase the flash flood threat on Wednesday and Thursday, especially in areas where the ground is already saturated.
In Oklahoma, forecasters warn that some areas could receive 2 to 5 inches of rain on Wednesday, though the exact location remains uncertain. Some models suggest west-central and north-central Oklahoma, including the Weatherford, Enid, and Ponca City areas, could be affected. If the cold front shifts farther southeast, the heaviest rainfall might threaten the Interstate 44 corridor, encompassing Lawton, Oklahoma City, and Stillwater.
Additional storms are expected across western Texas on Tuesday evening as winds strengthen just above ground level. Forecasters in Wichita anticipate the greatest potential for larger hail before approximately 8 p.m. to 9 p.m. Tuesday, followed by a heightened risk of damaging winds as storms merge. Heavy rain is also a concern overnight, particularly if successive thunderstorms track over the same locations.
Farther northeast, storms could spread from the lower Missouri Valley into northern Illinois overnight Tuesday. Hail and gusty winds remain possible, with a greater damaging wind threat if storms continue to draw in warm air from near the ground. Central and southern Iowa face increasing chances of showers and thunderstorms late Tuesday, with a stronger storm capable of producing hail possible in the southern part of the state.
More widespread rain is anticipated in Iowa Wednesday night and Thursday as the main weather system moves northeast. The Weather Prediction Center has highlighted a "Slight Risk" of excessive rainfall across parts of the southern and central Plains into the lower Missouri Valley on Wednesday. Some thunderstorms could produce 1 to 2 inches of rain per hour or more, raising concerns about rapid runoff and persistent flood threats through Thursday.
Hurricane Simon was a Category 2 hurricane with sustained winds of 105 mph on Monday. It was moving west slowly but was forecast to turn northeast and approach Mexico's west-central coast Wednesday into Thursday. Forecasters expect Simon to remain a hurricane through midweek, possibly strengthening before rapidly weakening after moving inland. In Oklahoma, rain and thunderstorms may linger through Thursday before gradually easing from north to south after nightfall.