Earlier today on the Weather MN blog we warned about a line of severe storms in central South Dakota that could blast parts of Minnesota later this afternoon, and the situation is becoming clearer, with the National Weather Service watching a developing derecho packing damaging winds up to 90 mph.
"A derecho with embedded significant severe wind gusts appears probable from central to eastern South Dakota into southwest Minnesota and northern Iowa into this evening." the Storm Prediction Center says.
The latest update from the SPC has elevated the severe risk in southeast South Dakota, southwest Minnesota and northwest Iowa from a level 3 of 5 enhanced threat to a level 4 of 5 moderate risk.
The line of storms is expected to maintain its strength as it approaches Sioux Falls – along and north of the Interstate 90 corridor – by about 3 p.m., at which point it would begin threatening southwestern Minnesota and northwestern Iowa, according to the SPC.
"An intense thunderstorm complex has developed over SD & will impact far-southwest MN this afternoon," says the Twin Cities office of the National Weather Service. "Damaging wind gusts of 70-80 mph are the primary hazard. If this complex takes a more easterly track, the threat for damaging wind increases across south-central MN."
The SPC notes that most models are doing a poor job of simulating what could happen with the possible derecho, though forecasters did point out that the model shown below has a decent handle on what's happened so far. Here's how that model shows things playing out the rest of the afternoon.
What's a derecho? It's basically a line of intense storm that produces wind damage for more than 240 miles. Here's the NWS definition:
"A derecho (pronounced similar to "deh-REY-cho") is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. Although a derecho can produce destruction similar to the strength of tornadoes, the damage typically is directed in one direction along a relatively straight swath. As a result, the term "straight-line wind damage" sometimes is used to describe derecho damage. By definition, if the wind damage swath extends more than 240 miles (about 400 kilometers) and includes wind gusts of at least 58 mph (93 km/h) or greater along most of its length, then the event may be classified as a derecho."
BMTN Note: Weather events in isolation can't always be pinned on climate change, but the broader trend of increasingly severe weather and record-breaking extremes seen in Minnesota and across the globe can be attributed directly to the rapidly warming climate caused by human activity. The IPCC has warned that Earth is "firmly on track toward an unlivable world," and says greenhouse gas emissions must be halved by 2030 in order to limit warming to 1.5C, which would prevent the most catastrophic effects on humankind. You can read more here.