Anatomy of the 2012 Duluth flood

10.10″ Highest observed rainfall total

(Reported by an NWS employee 4 mi NE of Duluth)

7.24″ Preliminary storm total at Duluth NWS office

(All time greatest 24 hour rainfall total on record for Duluth)

5.79″ previous all time 24 hour rainfall record in Duluth (August 22 & 23, 1978)

16.6 feet – new “flood of record” on the St. Louis River at Scanlon

15.8 feet – Previous flood of record from 1950 (62 years ago)

One year ago, Duluth residents went to be to the sound of thunder...and heavy rainfall. They woke up to a disaster.

Over 10" of rain triggered the worst flood in the history of Duluth left more than 100 million in damages to infrastructure as it washed out streets, sidewalks and swallowed cars in massive sinkholes.

Synoptic Setup: "Flash Floods 101"

The weather pattern near Duluth last June 19-20th was a classic setup for potential "nocturnal" thunderstorms. A slow moving warm front just south. Warm humid air mass with dew points in the 60s to near 70F riding in from southern Minnesota.

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A slow moving upper wave to generate lift...and a nearly stationary surface boundary to focus developing thunderstorms. As the storms formed they moved over the same ground again and again...a process we cal "training" in meteorology. Like box cars on a train, each storm dumped it's payload of torrential rain over the Duluth area.

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The result? A devastating "flood of record" for the Duluth area. The effects of the Duluth Flood were immediate, severe and unprecedented.

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"Feisty The Seal Flood of 2012"

In every disaster there’s usually one photo that captures the essence of the event. The photo of a scared looking "Feisty The Seal"  after being swept away from the Lake Superior Zoo by floodwaters does the trick for me on this one. I'm tempted to call this “The Great Duluth Seal Flood of 2012.”

Records Smashed:

The Great Duluth Flood of 2012 taught us something about our perceptions of Minnesota weather.

Records are made to be broken.

In just a few hours, the flood set many all time rainfall and flood records for Duluth and surrounding areas as a wide swath of 6" to 10" rainfall pounded the area last June.

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Here's an excellent description of the event from the perspective of the Duluth NWS Office. There is also an excellent hour by hour account of the flood.

In the week leading up to the flooding rains of June 19th-20th, parts of northeast Minnesota had received 2-4 inches of rain as numerous storm systems moved across the area. This helped to saturate the soil which primed the Duluth area for runoff in the extreme rain event that we received. On Tuesday, June 19th a cold front that had move through the previous day began to return north as a warm front, setting up stationary just south of Duluth. This front helped provide continuous lift for thunderstorms that developed over east central Minnesota tracking northeast into the Duluth area, the north shore of Lake Superior and into northwestern Wisconsin. The official rainfall in Duluth on the 19th was 4.14 inches. The thunderstorms finally ended when a strong cold front moved through Wednesday afternoon June 20th, but not before dumping another 3.11” at the airport. The official Duluth total rainfall for the event was 7.25”. Duluth International Airport broke several rainfall records during this flooding event. Locally high amounts in the 8-10 inch range were reported throughout Duluth neighborhoods and along the North Shore of Lake Superior.

A swath of impressive rainfall amounts ranging from 5-10 inches fell over much of the NWS Duluth area of responsibility during the period of June 19th-20th. Numerous roads were washed out from the deluge of rain from Carlton County through the Duluth metro area and into Douglas County and Bayfield County in Wisconsin.

A state of emergency was declared in Duluth, Hermantown, Cloquet, Barnum, Moose Lake and Superior, WI.

The steep terrain, and numerous creeks and rivers, played a significant role in the devastating damage and flooding that occurred in the Duluth community. The Fond Du Lac and West Spirit Mountain neighborhoods of Duluth and Thomson Township in Carlton County were evacuated.

A raging Kingsbury Creek flooded the Lake Superior Zoo, drowning over a dozen animals. Two seals were swept from their enclosures, but were returned safely after being found on a local street. The polar bear escaped its exhibit, but was safely returned after being tranquilized by a dart.

The Chester Creek Dam on the Chester Creek that runs through the heart of Duluth failed during the event.

An 8-year-old boy was swept into a culvert while playing in the flood waters in Proctor. He was swept through the culvert for 6 or 7 blocks, but besides some scrapes, was unharmed.

Why Duluth?

One of the reasons this mega flood happened in Duluth is the unique "flood geography" of the North Shore. Think of quickly dumping a bucket of water down a steep driveway.

Can it happen again?

Many have asked me if events like the Duluth Flood can happen again. The answer is not if...but when. With the increase in extreme rainfall in Minnesota, it's only a matter of time until the next 5" or 10"+ rainfall event in a major Minnesota city.

Expect the unprecedented.