As we look at the storm damage left behind by severe storms in the Twin Cities early Friday morning, it’s becoming clear the highest wind gusts were likely well above the severe threshold of 59 mph.
Photos shared on social mdia and storm reports show dozens of large trees uprooted.
This kind of damage is typically seen with winds between 70 and 90 mph.
Radar images show intense downburst signatures
The squall line that blew into the Twin Cities around 3 a.m. Friday showed signatures and Doppler data that supports the notion of winds between 70 and 90 mph.
Note the intensity and solidity of the line in reflectivity mode as it tore into the western Twin Cities. A sharp “leading edge gradient” shows that the storm packed sudden heavy rainfall and high winds in the gust front on the leading edge.
Doppler radar images of velocity data showed winds near ground level between 70 and 90 mph in Dakota County. Check out these Doppler velocity scans that Twin Cities meteorologist Tony Dello posted overnight.
Some of these Doppler-derived wind velocities are a few hundred feet above ground level, but descending air in downbursts can push these to ground level at times. And gusts can be considerably higher at treetop level than on the ground.
Wind gusts on the ground were clocked at 64 mph a few miles to the north at the Minneapolis-St. Paul International Airport.
If there were weather stations in the parts of Dakota Country with extensive tree damage, the extensive tree damage suggests they would have clocked wind gusts between 75 and 90 mph.
Wind vs. tornado damage
Another point about Friday morning’s severe thunderstorms. Straight-line wind damage from severe thunderstorms is usually more extensive and covers a wider area than damage from most tornadoes. Far more damage is caused by “just thunderstorms” than tornadoes in Minnesota and most areas.
That’s illuminating weather food for thought as you consider how to react in severe thunderstorm watch and warning situations.
Your support matters.
You make MPR News possible. Individual donations are behind the clarity in coverage from our reporters across the state, stories that connect us, and conversations that provide perspectives. Help ensure MPR remains a resource that brings Minnesotans together.