US: Adverse weather forecast across the Northern Rockies and Plains and Upper Midwest regions through at least early May 30

Event

Severe weather is forecast across portions of the Northern Rockies and Plains and Upper Midwest regions through at least early May 30. Thunderstorms will likely be accompanied by heavy rainfall, strong winds, hail storms, and possible tornadoes. Heavy rainfall may result in floods and flash floods, especially over low-lying areas or areas close to water bodies.

Government Advisories
As of early May 27, the National Weather Service (NWS) has not yet issued any widespread warnings in relation to the storm. Authorities will likely issue watches and warnings over the coming hours and days as the storm progresses.

The National Weather Service's (NWS's) Storm Prediction Center has warned of a "Slight Risk" (Level 2 on a five tier-scale) of severe thunderstorms across parts of the northern High Plain May 27 and across South Dakota and the Nebraska Sandhills May 28. An "Enhanced Risk" (Level 3 on a five tier-scale) of severe thunderstorms across central Nebraska northeastward into northwestern Iowa, eastern South Dakota, and southwestern Minnesota and a "Slight Risk" across eastern and central Nebraska northeastward into Minnesota and far western Wisconsin are in place May 29 through early May 30. Officials could update and possibly extend the coverage of weather alerts over the coming days.

Storms in the Slight Risk regions are not forecast to be widespread or long-lived. Isolated intense storms are possible; however, widespread damage is unlikely. Isolated intense storms are possible, which may contain hail, damaging winds, and a few tornadoes.

Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days, as well as tornado warnings advising the public to shelter in place. Disruptions to electricity and telecommunications services are possible where severe weather impacts utility networks.

Transport
The severe weather will likely contribute to transport disruptions throughout the region. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather could also trigger flight delays and cancellations at airports in the region, including but not limited to Minneapolis-Saint Paul International Airport (MSP). Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur in flood- or tornado-hit areas; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Review contingency plans and be prepared to move quickly to shelter if tornado warnings are issued. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

National Weather Service