11 Aug 2021 | 02:24 AM UTC
US: Adverse weather forecast across the Midwest through at least early Aug. 12 /update 1
Heavy rainfall, strong winds, hail, flooding, and possible tornadoes forecast across the Midwestern US through at least early Aug. 12.
Event
Thunderstorms with rounds of heavy rainfall, strong winds, flooding, and possible tornadoes are forecast to occur across portions of the Midwestern US through at least early Aug. 12. Affected areas include northern Illinois, northern Indiana, southeastern Iowa, southern Michigan, northeastern Missouri, northwestern Ohio, and southeastern Wisconsin.
The Storm Prediction Center (SPC) has issued an "Enhanced Risk" (Level 3 on a 5-tier scale) for severe weather for northeastern Illinois and southeastern Wisconsin from Aug. 10 through early Aug. 11. A "Slight Risk" (Level 2 on a 5-tier scale) for severe weather is in place for the rest of the affected area through at least early Aug. 12. Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.
Severe storms in the "Enhanced Risk" (Level 3) regions are forecast to be more numerous, persistent, and widespread than those in the region where a "Slight Risk" (Level 2) is in effect. 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.
The Weather Prediction Center (WPC) has issued a "Slight Risk" for excessive rainfall for central Illinois, western Indiana, and far northeastern Missouri, where the heaviest rainfall is forecast. Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.
Government Advisories
As of late Aug. 10, officials with the National Weather Service (NWS) have issued severe thunderstorm watches and warnings for northeastern Illinois, northern Indiana, southwestern Michigan, and far eastern Wisconsin. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Hazardous Conditions
The storms will be capable of producing heavy downpours, damaging winds, hail, and tornadoes across the affected area through at least early Aug. 12. Should sustained heavy rainfall occur, it could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of 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 the soil has become saturated by heavy rainfall. Disruptions to electricity and telecommunications services are possible where significant flooding, landslides, or strong winds impact utility networks.
Transport
Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways including the I-10, I-40, and I-55 corridors. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.
Severe weather could also trigger intermittent flight delays and cancellations at regional airports, though these are unlikely to be severe or prolonged. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track inundation. Localized business disruptions may occur in low-lying areas.
Advice
Monitor local media for weather updates and related advisories. Out of an abundance of caution, 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. Charge battery-powered devices in the case of prolonged electricity outages.
