Residents near Grantsburg, Wisconsin did a double-take Tuesday afternoon. A rope-like landspout tornado danced across fields near Grantsburg.
A landspout tornado likely occurred this afternoon near Grantsburg, WI from a very small thunderstorm. These types of tornadoes are very difficult to see on radar. Please let us know if you have any information to help us determine where it landed. pic.twitter.com/6IDnOhMvyU
— NWS Duluth (@NWSduluth) August 7, 2018
Anatomy of a landspout
Landspouts are small tornadoes that are not associated with typically larger tornadic supercells. The parent cells generally don’t show organized rotation and typically go undetected on Doppler radars.
— NWS Twin Cities (@NWSTwinCities) August 7, 2018
Here’s more from NOAA on landspouts and other non-supercell type twisters.
Non-supercell tornadoes are circulations that do not form from organized storm-scale rotation. These tornadoes form from a vertically spinning parcel of air already occurring near the ground caused by wind shear from a warm, cold, or sea breeze front, or a dryline. When an updraft moves over the spinning, and stretches it, a tornado can form. Eastern Colorado experiences non-supercell tornadoes when cool air rushes down off the Rocky Mountains and collides with the hot dry air of the plains. Since these types of tornadoes happen mostly over scarcely populated land, scientists are not sure how strong they are, but they tend to be small.
One non-supercell tornado is the gustnado, a whirl of dust or debris at or near the ground with no condensation funnel, which forms along the gust front of a storm.
Another non-supercell tornado is a landspout. A landspout is a tornado with a narrow, rope-like condensation funnel that forms while the thunderstorm cloud is still growing and there is no rotating updraft – the spinning motion originates near the ground.
Waterspouts are similar to landspouts, except they occur over water. Damage from these types of tornadoes tends to be EF2 or less.
The maps look pretty classic as we move into the second week of August. Temperatures look and feel like summer for the foreseeable weather future. The numbers keep coming up 80s. Temperatures run about 5 degrees warmer than average over the next week. The average high/low now for the Twin Cities are 81/62.
Weekend Dakota heat wave
Many places in the Dakotas are likely to feel near triple-digit heat this weekend. Temperatures near 100 could push into the Red River Valley.