Two seasons in one
A potent low pressure system and associated frontal boundaries will make for more messy, stormy weather and delays for drivers from the Rockies to the Great Lakes. This system spawned several tornadoes yesterday, September 10, mostly in rural, low-population areas. However, one tornado struck Sioux Falls, South Dakota, today in the pre-dawn hours.
The worst storms today, which will be severe in the afternoon and evening, will produce very large hail, powerful winds and more tornadoes from northeastern Colorado, southeastern Wyoming and the Nebraska Panhandle to northern Iowa, southern Minnesota, central Wisconsin and lower Michigan. The National Weather Service (NWS) outlooks, housed inside the FreightWaves SONAR Critical Events platform, are highlighted in the map directly below.
Drivers will have to slow down at times on I-80 from Cheyenne to Grand Island, I-76 east of Denver, I-90 from Sioux Falls to La Crosse, and I-29 from Sioux Falls to Omaha. Severe storms may also hit Milwaukee and Detroit. Storms have already flooded portions of northern Nebraska and western Iowa today. More localized flash flooding may lead to roadblocks of secondary routes or interstate ramps in the target areas.
The same system will dump two to three inches of rain across parts of Big Sky country, where the ground is already saturated. Runoff will likely cause flooding along the Milk River, especially in northeastern Montana. The National Weather Service has issued a Flood Watch for these areas north of I-94.
Meanwhile, up to four inches of early season accumulating snowfall will cover roads in the Bighorn Mountains of Wyoming through tonight, with an inch or two in the high elevations of Yellowstone National Park. Beartooth Pass on US-212 in Montana could see six to eight inches. This won’t affect interstate travel, but rather drivers making local or regional deliveries into these areas.
Tropical update
The Atlantic basin is free of tropical cyclones at this time. However, one disturbance in the Caribbean has potential to become an organized system. The tropical wave is located just north of Haiti and will drop locally heavy rainfall across portions of the Bahamas over the next few days, including some areas recently devastated by Hurricane Dorian. The National Hurricane Center (NHC) is giving this disturbance a 40 to 60 percent chance of turning into a tropical depression or tropical storm by this weekend or early next week as it possibly moves into the Gulf of Mexico.
Have a great day and be careful out there!