Teetering on the brink of a high risk for severe weather today, the Upper Midwest stands to see a widespread and significant severe weather event today. The Storm Prediction Center has posted a broad moderate risk across portions of Nebraska, South Dakota, Minnesota and ALL of Iowa.
It’s expected that we’ll see a long duration, massive storm complex develop, affecting all of these areas and perhaps even more. This outbreak of severe weather is expected to occur in different ways, essentially covering the entire life cycle of a large and mature severe thunderstorm complex.
Initial development is expected to take place in areas of Wyoming and Nebraska. These initial supercellls are expected to produce tornadoes, some possible strong. You can see in the graphic to the right the highest tornado risk stays mainly out of Iowa, with the exception of the far western part of the state. At first, a handful of storms will develop before additional storms increase the affected area.
As they move further east and begin to shift in their life cycle, extremely large hail is possible over a large area, primarily Nebraska. Looking at the graphic to the left, again, you can see the greatest risk for large hail stays mainly west of Iowa. Just like the tornado risk, this does not mean Iowa won’t see any large hail, but it won’t be the primary threat.
The graphic to the right shows Iowa’s primary threat tonight… strong, damaging winds. There is a concern a large derecho will form, producing widespread damaging winds over a very large area. This could lead to a large amount of tree and power line damage as well as structural damage. Power outage could become widespread if such a storm forms tonight.
If all of this happens, it’s expected to be an all night event, affecting the state well into the overnight and early morning hours of Monday. This is a very dangerous situation and I urge EVERYONE in Iowa to stay updated with the latest forecasts. We’ll continue to provide updates here as needed and will launch the live chat when the weather threatens.
I want to focus on today’s threats so I’ll just briefly mention the entire state finds itself under a slight risk for severe weather both Monday and Tuesday. We’ll have more on those threats after we deal with tonight’s issues.
Also need to mention the secondary threat with tonight’s storms and future rounds of rain this week. With a heavily saturated ground, flash flooding and river flooding is possible in some areas. Currently southeast Iowa faces the biggest threat from more heavy rains as many rivers in that area are already out of their banks.
Areas further north could face similar problems depending on where the heaviest rain falls. It’s something we’ll certainly have to keep an eye on tonight and the rest of the week.