Cold Front Moving Through the Northeast U.S. Monday; Atmospheric River to Impact the Pacific Northwest Midweek

A cold front will cross the Great Lakes and Northeast U.S. through Monday with gusty winds and areas of rain showers. A strong atmospheric river is expected to move into the Pacific Northwest by midweek bringing a threat for moderate to heavy rainfall, gusty winds, and mountain snows for parts of Washington, Oregon, northern California, and the Sierra Nevada. Read More >

Overview

After a cool, cloudy start to the day, the atmosphere became very unstable during the afternoon of July 8, 1999 and produced significant thunderstorm activity. A tornado formed just northwest of the town of Lewiston, MN (Winona Co.), tracked right through town, and then dissipated southeast of town near a farm. There were a couple injuries and lots of damage in town.

As the storms tracked into Wisconsin, they produced another brief tornado in Mondovi, WI (Buffalo Co.) along with areas of wind damage. Rotation from the same storm that struck Lewiston went across the Mississippi River valley near La Crosse and was witnessed by the La Crosse National Weather Service just east of town. Winds gusted to 72 mph at the NWS office, with other high gusts from different directions. There was wind damage across parts of central La Crosse County, WI.

In summary, there were two tornadoes - one F2 and one F1 - and sporadic wind damage.

The clear path of the Lewiston, MN tornado as it moved into nearby farm fields on July 8, 1999

Tornado
Photos
Radar / Maps
Storm Reports

Tornadoes:

Tornado #1 - Lewiston, MN
Winona County

Date	July 8, 1999
Time (Local)	7:20-7:30 p.m. CDT
F Rating	F-2
Est. Peak Winds
Path Length	3.5 miles
Max Width	100 yards
Injuries/Deaths	2 injuries
Summary: The tornado touched down on the northwest side of Lewiston, damaged nearby homes and a farm implement dealer before tracking further into town. The tornado intensified right in the middle of town and tracked along main street to the southeast corner of town. Numerous homes along main street suffered extensive damage with broken windows, damaged roofs and downed trees. One home had the entire roof taken off while at least 4 cars were demolished from debris landing on them. The tornado damaged a few homes in the southeast corner of Lewiston before entering corn fields for approx. 2 miles further. One farm had every building, except the house, demolished. The track of the tornado was clearly visible in the corn fields from the air. The tornado lifted just before the intersection of County Roads 23 and 25. There were 2 minor injuries reported, with 4 homes completely destroyed and 26 others sustaining damage. Length of the tornado track was 3 1/2 miles and peak width was approx. 100 yards. Peak damage indicates an F2 tornado, but most of the damage was F0/F1 variety. Interviews confirmed the tornado touched down at 7:20 p.m., but people heard outdoor warning sirens between 7:00 and 7:05 p.m. The National Weather Service issued a tornado warning officially at 7:00 p.m.

Track Map

Tornado #2 - Mondovi, WI
Buffalo County

Date	July 8, 1999
Time (Local)	6:20-6:40 p.m. CDT
F Rating	F-1
Est. Peak Winds
Path Length	10 miles
Max Width	120 yards
Injuries/Deaths	3 injuries
Summary: A broad area of circulation produced occasional small tornado touch- downs across northeast Buffalo county, from approx. 8 miles southwest of Mondovi, through the city of Mondovi, to 4 miles northeast of Mondovi. Numerous trees were sheared off along the path with occasional homes or barns sustaining minor damage. Two homes in Mondovi had roofs removed or garages damaged. Interviews indicated the tornado hit Mondovi itself around 6:32 p.m. on Thursday. Lighter damage, with mainly trees blown down, occurred in a path approx. 250 yards at times but the structural damage to homes was very narrow, 30 yards at most. This type of damage appears to be F1 in intensity and there were 3 reported injuries. A severe thunderstorm warning was issued, mentioning the possibility of tornadoes, at 6:22 p.m. A tornado watch was issued by the Storm Prediction Center of the National Weather Service for this entire area at 5:50 p.m. on Thursday afternoon.

Photos:

Lewiston, MN


House damage in Lewiston	F-2 damage on Main St. in Lewiston	Roof damage	The path of the tornado east of town, impacting a nearby farm


Debris heavily damaged a van on Main St.	A look down Main St. with damaged homes	The water town was left untouched	One view of the tornado


Debris thrown on a clothes line	Home damage in Lewiston	Truck heavily damaged from falling debris

Radar & Maps:


At the time, the most significant tornado sampled by the relatively new WSR-88D radar at NWS La Crosse. The rotation is clearly depicted by this storm-relative velocity image at tornado time.	Animation of storm cells going through Winona County, including the storm that produced the Lewiston, MN tornado.	Surface map for July 8, 1999

Reports


Storm Reports from July 8, 1999

Warning Lead Time

Counties & Issuance Time	Lead Time

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Cold Front Moving Through the Northeast U.S. Monday; Atmospheric River to Impact the Pacific Northwest Midweek

Lewiston, MN Tornado of July 8, 1999