Storm Impacting the Northwest U.S.; Fire Weather Conditions in Southern California; Severe Weather in the South

A Pacific storm is bringing areas of low elevation rain, moderate to heavy mountain snow, and high winds to the Northwest. Strong Santa Ana winds and very dry conditions are producing elevated to critical fire weather conditions in southern California. Isolated strong to severe thunderstorms are possible through early Wednesday morning across parts of northeast Texas into western Tennessee. Read More >

Overview

During the daytime hours of July 19, 2017, a severe thunderstorm developed across portions of northwestern South Dakota and started to track southeast. Before the afternoon was finished, this severe storm tracked across South Dakota, Minnesota, Iowa and eventually finished the day in Illinois.

This storm produced extensive straight line winds in excess of 80 mph as it rolled through Huron, SD. Winds continued in Brookings, SD where 74 mph winds were reported. As the storm continued into western Minnesota, damage to barns, sheds, power poles, trees, and crops were reported from near Lake Benton, MN to areas south of the city of Marshall, MN. This storm did also produce two very small and brief tornadoes south of the city of Marshall, MN. These short tracked and short lived twisters, helped increase localized wind speeds to near 100 mph.

This storm reorganized itself as it moved through south central Minnesota and into Iowa, producing widespread wind damage as it moved through. Beneficial, but very localized rainfall amounts as high as two inches were reported from thunderstorm activity.


High Resolution Satellite Data	Storm Damage Near Marshall	Storm Damage Near Lake Benton, MN

Wind Damage & Brief Tornado Info
Radar
Storm Reports
Rainfall

Wind Damage and Brief Tornado:

Wind Damage Photos

Strong straight line winds were a common feature of this storm complex as it move through the area. Wind gusts were reported as high as 83 mph in the city of Huron, SD, 74 mph in Brookings, SD. These strong winds damage crops, buildings, power lines, and even flipped an irrigation system over near Huron, SD. As this storm moved southeast, strong winds continued to produce damage into western Minnesota.


Blown Over Irrigation System Near Huron, SD	Grain Bin Damage Near Lake Benton	Power Poles NW of Lake Benton	Flattened Corn Near Huron, SD

Barn Damage NW of Lake Benton	Damage Storage Shed Near Marshall	Shed Damage Near Marshall, MN

Tornado Information

As this system moved through Lyon County in Minnesota, strong straight line winds were reported in the southern half of the county. In addition to the strong straight line winds, two very brief, short track tornadoes touched down south of the city of Marshall. These tornadoes were likely only on the ground for a minute or less, but locally enhanced the winds in the area to produce very narrow tracks of damage. The straight line winds associated with the tornadoes led to significant damage to trees, storage buildings, machine shed and grain bins. While no photos were taken of the tornadoes, local residents did report seeing them.

Tornado Details Location: 5 Miles south-southwest of Marshall, MN Path Length: 50 Yards Path Width: 10 Yards Estimated Wind Speeds: 80 - 90 mph EF Rating: EF-0 Location: 4 Miles south of Marshall, MN Path Length: 50 yards Path Width: 10 yards Estimated Wind Speeds: 90-100 mph EF Rating: EF-0
	Initial Tornado Development Point (NWS Survey)	Converging Tree Branches (NWS Survey)

	Grain Bin Damage (NWS Survey)	Tree Damage (NWS Survey)

Radar:

Regional and Local Radar Loops and Images



Radar Signature Producing 83 mph Winds in Huron, SD	Storm Dynamics Changing Near Brookings, SD	Strong Winds Rebuild South of Marshall, MN	Cross Section Showing Strong Winds Descending Through The Storm

Storm Reports

Here is a look at storm reports from this event. Click HERE for an interactive view.

Regional Storm Reports

Local Storm Report

Location	ST	Event Type	Mag.	Source	Remark
2 N Huron	SD	TSTM WND GST	83	asos
6 NNE Huron	SD	TSTM WND GST	70	trained spotter	also nickel size hail.
6 NW Cavour	SD	TSTM WND DMG	0	emergency mngr	irrigation pivots damaged.
3 E Cavour	SD	TSTM WND GST	72	mesonet
7 S Cavour	SD	HAIL	2.5	emergency mngr	golf ball to tennis ball size.
2 N Huron	SD	TSTM WND GST	83	asos
2 NNE Brookings	SD	TSTM WND GST	74	mesonet
10 ESE White	SD	TSTM WND DMG	0	public	large barn and grain bin destroyed. power poles and several trees blown over. report via social media.
1 WNW Lake Benton	MN	TSTM WND GST	61	mesonet
Lake Benton	MN	TSTM WND DMG	0	trained spotter	tree branches down.
5 WSW Delft	MN	TSTM WND GST	60	trained spotter
3 SW Gregory	SD	HAIL	1	public
Windom	MN	HAIL	1	public
Windom	MN	HAIL	1.5	public