Severe and unusual bow echo wreaks havoc in metro

A severe and somewhat unusual storm raced through southern Minnesota overnight and took direct aim at the Twin Cities. The storms produced winds to 70 mph, which knocked out power and downed numerous trees.

https://twitter.com/HahnKali/status/622296035902099456

Weather Underground radar loop shows the classic bow echo that developed as it pushed east through the metro in Wisconsin.

The storm produced numerous wind damage reports. A tornado was sighted in Green Isle and Watertown, where trees and cars are reportedly damaged. Here's a look at the Doppler radar signatures indicating tornadic rotation in Watertown from the Twin Cites NWS around midnight. The MSP Doppler also detected airborne debris.

Some storm reports from the Twin Cities NWS.

4 WSW Watertown [Carver Co, MN] 911 CALL CENTER reports TORNADO at 17 Jul, 11:59 PM CDT -- CARS FLIPPED AND STRUCTURAL DAMAGE REPORTED. DUAL POL RADAR OBSERVED TORNADO FOR 2 TO 3 MINUTES BEFORE WEAKENING. TORNADO HEADED EAST NORTHEAST. EXTENT OF DAMAGE UNKNOWN.

2 SW Watertown [Carver Co, MN] PUBLIC reports TSTM WND DMG at 12:54 AM CDT -- TWELVE TO SIXTEEN INCH DIAMETER TREES SNAPPED OFF ABOUT 20 FEET ABOVE THE GROUND. REPORTED VIA TWITTER.

Watertown [Carver Co, MN] LAW ENFORCEMENT reports TSTM WND DMG at 12:02 AM CDT -- POWER LINES AND MANY TREES TOPPLED IN THE CITY.

2 SW Watertown [Carver Co, MN] PUBLIC reports TSTM WND DMG at 12:54 AM CDT -- TWELVE TO SIXTEEN INCH DIAMETER TREES SNAPPED OFF ABOUT 20 FEET ABOVE THE GROUND. REPORTED VIA TWITTER.

Lakeville [Dakota Co, MN] MESONET reports TSTM WND GST of M70 MPH at 12:41 AM CDT -- VIA WEATHER UNDERGROUND/THE WEATHER CHANNEL.

NEW Brighton [Ramsey Co, MN] BROADCAST MEDIA reports TSTM WND GST of E70 MPH at 12:56 AM CDT -- SIXTY FIVE TO 70 MPH WINDS REPORTED 

2 WNW Richfield [Hennepin Co, MN] COCORAHS reports TSTM WND GST of M67 MPH at 12:40 AM CDT --

Waconia [Carver Co, MN] PUBLIC reports TSTM WND DMG at 12:23 AM CDT -- HUGE TREE LIMBS SMASHED VEHICLES IN TOWN. REPORT VIA TWITTER.

Xcel Energy reports nearly 119,000 customers are without power as of early Saturday morning.

I expect numerous additional reports of storm damage to become evident as daylight grows across the Twin Cities.

Unusual Storm

This storm system was unusual on several fronts. Unlike Sunday's bow echo that tore through the Brainerd lakes area, this one did not weaken as it approached the Twin Cities. In fact it strengthened and ultimately became tornadic about 30 minutes before it hit the west metro. I suspect we will find out a rare gravity wave like the event of June 16, 2014 may have enhanced this storm.

The storms also featured high winds well after the main bow echo passed. These rear jet inflow gusts did some additional damage as winds gusted to 60 mph at Twin Cities Airport well after the initial storm front.

MSP Intl Airport [Hennepin Co, MN] ASOS reports NON-TSTM WND GST of M60 MPH at 1:33 AM CDT -- STRONG WINDS WELL BEHIND THE LINE OF STORMS.

I talked about the gusty winds continuing behind the storms during over 2 hours of nearly continuous live coverage on MPR News. NOAA's Storm Prediction Center also noticed the unusual trend feeding these storms.

SUMMARY...BOWING QLCS WILL CONTINUE TO PRODUCE WIDESPREAD STRONG TO EMBEDDED SEVERE WIND GUSTS AND A BRIEF TORNADO OR TWO ACROSS MAINLY W-CNTRL WI. TRAILING PORTION OF THE LINE MIGHT INTENSIFY NEAR THE MN/IA BORDER TOWARDS THE MS RIVER.

DISCUSSION...QLCS WITH A WELL-DEFINED BOW/COMMA-HEAD SHOULD CONTINUE TO PROGRESS E/SE AMID CURRENT SPEED AROUND 45 KT. MEASURED ASOS/AWOS GUSTS ALONG THE LEADING EDGE OF THE LINE HAVE BEEN AROUND 40 KT WITH EMBEDDED SWATHS TO 55 KT. WAKE-LOW WINDS HAVE CONSISTENTLY MEASURED FROM 45-55 KT AS WELL. MPX VWP DATA SAMPLED A 70-KT REAR-INFLOW JET BEHIND THE BOWING PORTION OF THE LINE WHICH HAS NOW PROGRESSED INTO W-CNTRL WI. THIS PART OF THE LINE WILL CONTINUE TO BE THE PRIMARY SEVERE THREAT WITH POTENTIAL FOR WIDESPREAD DAMAGING WINDS.

I hope you and your are all safe and well, and all your trees are still in good shape. Behind the storm front we enjoy a much quieter weekend.