Felt like 120F: More heat Friday, Saturday severe risk

Severe Summer of 2016

This is turning into the Severe Summer of 2016 across Minnesota.

NOAA's Storm Prediction Center tallies 33 preliminary tornado reports so far this year in Minnesota.  That's already the second highest preliminary total since 2010 produced a finalized record tally of 113 twisters in 2010. Throw in multiple bow echo-driven straight-line wind damage events and this is probably the most active summer severe season in six years.

That's not news to many of you who are cutting trees off your home or cabin, and waiting for power to be restored.

Widespread damage reports continue to flow in from this morning's massive damaging wind event that tore across northern and central Minnesota.

https://twitter.com/WDAYWeather/status/756168868758822913

Widespread wind damage is reported across northern Minnesota east into the Duluth area. Scenes like this are common across the Northland.

Multiple bow echoes

I saw at least two 'bowing line segments' meteorologists call bow echoes race across Minnesota overnight.

The Duluth NWS radar loop shows the fast moving severe squall line racing east. The southern end of the line clipped the Twin Cities metro early this morning with some 50+ mph gusts and scattered tree damage reports.

The meteorology behind the blowdown

The meteorological recipe behind a massive squall line outbreak is pretty straight forward. Take one steamy air mass with dew points in the tropical 70s. Mix with strong upper level winds. Top with a generous helping of cold air aloft to create instability and promote rising storms. That's how you get a massive windstorm that likely knocked down thousands of trees and took out power to nearly 100,000 in the Upper Midwest.

Here's more from the Duluth NWS as they fill in the blanks on last night's damaging wind event.

More widespread wind damage accompanied a long line of storms last night. The storms entered northeastern Minnesota late evening of July 20th and exited into eastern Wisconsin after 5:00 am today.

Damage was reported from the Canadian border to the Brainerd Lakes area and east across northern Wisconsin. There are reports of tress down and power outages across much of the northland.

Initial damage assessments indicate that the areas worst hit include the Winton area, Duluth, Aitkin Hill City.  Power has been out to a large part of the Duluth area. According to Minnesota Power, some areas may be without power over the weekend.

This information will be updated and information added to during the next few days.

I tracked NWS wind gust reports overnight between 60 and 75 mph across northern Minnesota and Wisconsin. Given the extensive tree damage, I estimate gusts may have topped 80 mph in many areas between observing sites.

Heat wave: Felt like 118F in Eagan, 121F in Alexandria

As forecast, Thursday brought some of the highest heat index readings in years to Minnesota. Many Twin Cities locations recorded heat index values of 115+. Two sites reported unbearable heat index readings of 120+ degrees!

Little relief until Monday?

We'll see some slight relief this weekend from the worst of the heat, but it may be until Monday until you really notice the cooler temperatures and lower dew points. The next low pressure wave brings another round of potentially severe thunderstorms Saturday.

Highs push well into the mid-90s again Friday afternoon. The last day of heat waves often ends up being the hottest, even after the core of the thermal ridge passes by. The warm overnight temperatures mean we don't have as far to warm as the previous day.

Sauna-like dew points near 70 degrees hang around this weekend. Real relief arrives by Monday as dew points fall back into the lower 60s and maybe even upper 50s.

• 9 days at or above 90 degrees so far at MSP in 2016

• 6 days combined at or above 90 degrees in past two years

• 11 days on average of 90+ each year at MSP

Long range: Moderation ahead

I have no doubt we'll rack up more 90-degree days this summer, but the next two weeks favor a slightly more moderate summer brand of warmth. The upper air charts suggest a more zonal east-west flow. That should mean temperatures closer to average over the next two weeks, with the core of the U.S. heat dome suppressed to the south. In theory.

NOAA's 16-day GFS temperature output for MSP suggests the majority of days in the 80s, with even a few 70s possible.

A whiff of September as we turn the calendar to August?

Hang in there Minnesota.