Floodwaters create new lakes and their own climate in the Red River Valley – Grand Forks Herald

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Editor’s note: This

the story was written

by Paul Huttner of MPR. The Herald shares it with readers courtesy of MPR.

ST. PAUL — I’ve been watching Minnesota weather for over 35 years. It’s something I’ve never seen before.

Massive flooding in northwest Minnesota has created new (temporary) lakes. Flood zones are so large that they are able to generate their own localized weather patterns.

Check out this tweet below from the Grand Forks NWS office. The dark areas are flood-created lakes oriented north-south. The lakes line up along either side of the Red River from northwest Minnesota and eastern North Dakota north into Canada.

Then watch the bumpy white line of cumulus clouds form east of the lake area. These are cumulus clouds developing along what is essentially a frontal convergence zone of lake breezes.

Lake breezes and sea breezes form as the land near bodies of water warms with strong sunshine like we had on Tuesday. The warmed air above the land rises and the denser, cooler air from the lake blows inland to take its place.

From NOAA:

“The sun warms both the ground and the ocean at the same rate.

However, because the heat from the ground remains confined to the top few centimeters of the ground, it is radiated back into the atmosphere, warming the air. As the air warms, its density decreases, creating a weak area of ​​low pressure called a “thermal depression”.

Over the adjacent water, cooler and denser air, pulled by gravity, begins to spread inland. This push of inland air from the ocean saps the less dense air above the land, forcing it to rise.

A sharp boundary develops due to the large difference between air temperature above land and above water. This boundary, called the sea breeze front, acts similarly to the cold front we typically encounter.

These temporary flood lakes may not last long, but they produce localized weather conditions that are very unusual in the Red River Valley.”

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