KMSP – Many folks in the north metro are still picking up the pieces from severe storms that ripped through the area late Tuesday night and early Wednesday. One tornado was confirmed by the National Weather Service (NWS) late last week, well a second one has now been recorded as well.
Just to the northwest of the first one, an EFO (the weakest of all twisters on the Enhanced Fujita scale) spent 12 miles on the ground from just east of highway 65 in Lake Elmo, to I-35 north of Forest Lake. A couple of structures and some extra tree damage is what lead the survey team to believe that a tornado may have occurred in the first place. So why did it take so long to confirm?
NWS survey teams spend hours combing through damage assessment observations and photos to come to their conclusions. Many of the stronger tornadoes are much easier to confirm because the damage is easier to spot and is all generally strewn about in every direction, indicating there was rotation with winds that moved through the area. But with weak tornadoes, especially with twisters that form in thunderstorm line segments, the damage is less dense, and far more scattered. Combine the scattered nature of the destruction with a storm that is already producing strong straight line winds, and you have a recipe for some confusion on whether or not the inflicted damage had any rotation to it. In some of these extremely complicated cases, the surveys can go through dozens of expert’s eyes to try and pinpoint a definitive answer. In this case, it took about 4 days.
So far, the official tornado tally for Minnesota stands at 13 for the year, but that is just through June 27th. All severe weather reports have to be submitted for confirmation and evaluation by the Storm Prediction Center before being confirm and tallied. This process can take 3 to 6 weeks. There are a half dozen or so more tornadoes that will likely get added to the tally for the year, with Minnesota near 20 through the middle of July.
by Cody Matz
July 16, 2017
