Posted at 7:12 AM on June 16, 2008
by Paul Huttner
I remember first hearing the term "gustnado" from famed severe storms researcher Chuck Doswell many years ago.
Saturday evenings line of thunderstorms brought many reports of gustnadoes into the Twin Cities NWS office.
Gustnadoes are mini vortices that form along the gust front on the leading edge of strong thunderstorms. Different from tornadoes, they can originate from the ground up, and are thus not connected to the circulation from the parent storm like tornadoes. They are often not connected to the shelf cloud that accompanies the leading edge of the gust front.
Gustnadoes can reach speeds of 60 to 80 mph, and can do damage. They are really considered part of the overall gust front, or straight line winds at the front edge of severe thunderstorms. They are not tornadoes, but if you see one you can assume they accompany a potent gust front, and you should expect high winds as it passes.
Speaking of high winds, we had many reports of 60 mph winds in the metro Saturday night. The spotty damage was mostly due to downed trees. We've had so much rain lately that it's a bit easier than normal to push down trees in high winds because soils are so wet that the roots give way.
This week looks quieter in the metro. We'll warm to near 80 by mid-week, and stay there through the weekend. Our average high hits 80 on Wednesday, so we'll finally be near average for a change.
Look for the big strawberry ripening (Dakota) full moon Wednesday, and the summer solstice Friday at 6:59pm.
The weather maps are easing us into a more summery pattern this week. Look for fewer storms, more sun, and warmer temperatures along with less wind as the week progresses.
Hopefully we won't see any more gustnadoes this week!
Thursday (June 12, 2008) around 9:15 pm we saw about 10 of these "guspnatos" from one vantage point driving west from Willmar toward Raymond. I didn't have a name for it at the time (thought it was a wind shear) We thought we had eluded them when we turned south but then one appeared in front of us quite unexpectedly. It seemed to rise up from the ground. The car shook pretty good and got sand blasted. My two-year-old grandson who had been riding quietly in his car seat, piped up with "I think its going to rain!"
Thanks for the great description.
Last Thursday you may have indeed seen gustnadoes west of the cities. But there were also reports of several small tornadoes!
You may have been very lucky, and just driven near an actual, but small tornado. I'm glad it worked out okay and you are safe!
Thanks again for the response.