After a mild start to May, the atmosphere above the central United States is ripe for an outbreak.
Unstable and severe thunderstorms are expected to develop across the Plains and Midwest through Tuesday, bringing the risk of severe EF3 or higher tornadoes, destructive hail, damaging winds and heavy rain to the region where spring’s most dangerous storms often arrive with significant force.
May is notorious for bringing severe thunderstorms across the Plains and Midwest, but this one may live up to that reputation. It’s a big change from the previously quiet start of the month, as jet stream patterns have previously suppressed widespread, severe storms.
The tornado threat is severe Sunday and Monday. The storm threat moves east on Tuesday.
Weather patterns also set the stage for wildfires. There is significant fire danger in the Southwest, from Arizona to southwestern Kansas. We discuss the timing of severe storms below, and then discuss the threat in more detail.
Sunday
Storms will develop rapidly over southeastern Nebraska and South Dakota in the mid-to-late afternoon. Afternoon storms could produce very large hail.
The tornado threat is highest this evening, occurring from approximately 4:00 PM to 10:00 PM ET in eastern Nebraska, southeastern South Dakota, and western Iowa, including Omaha, Lincoln, and Sioux City.
Monday
Severe thunderstorms can occur over a wide area as the largest surge of energy in the jet stream interacts with the large amount of moisture in the plains.
The supercell that erupts in the afternoon can whip up tornadoes, some of them EF2 or larger, and can produce very large hail. The greatest threat of strong tornadoes extends from central and eastern Kansas to southeastern Nebraska and northwest Missouri. Widespread damaging winds will be the biggest concern by late evening, but a few tornadoes remain possible late into the night.
What remains uncertain is how the morning storm and its clouds will affect afternoon conditions. This will help pinpoint areas with the greatest tornado threat. Areas where the storm from Sunday night will remain into the morning will see less energy from the afternoon and evening storms.
Tuesday
Thunderstorms are possible Tuesday morning from northern Texas to Michigan. The chance for strong to severe storms will increase again into the afternoon. However, if a cold front becomes the main trigger for storms, the tornado threat will decrease and wind and hail will become the main threats.
A Level 3/3 Very Significant Fire Threat exists for the Southern Highlands on Sunday and Monday. Areas from southwestern Kansas to the Texas Panhandle and northeastern New Mexico are under the highest threat, but the level 2/3 severe threat covers a much larger area, including most of New Mexico.
The same system that brings dangerous tornadoes to the Central Plains and Midwest will cause very dry and windy conditions to the Southern Highlands. Sustained winds of 25 to 30 miles per hour, gusts up to 50 miles per hour, and relative humidity below 10 percent, combined with dry fuels, can cause a fire to spread at a life-threatening rate, according to the National Weather Service.
