Red River Rising

Well, not yet, but soon. This year’s record snowpack fell on saturated frozen ground. If spring rains melt it all at once, residents along the Red will face record-breaking floods.

There is a huge amount of snow on the ground in North Dakota along the tributaries of the Red River, thanks to fall precipitation that was 150% – 300% of normal, and winter snows that have dumped up to 400% more precipitation than usual. If one were to melt this snow, it would amount to 4 – 6 inches of rain. If heavy rains occur at the same time that the snow melts, there is the potential for the greatest flood in history to affect the cities of Fargo and Grand Forks, the largest and third largest cities in North Dakota. NWS is giving a 35% chance that Fargo will see its greatest flood in history this spring, up from the 20% chance they gave in their February spring flood outlook.

The situation is similar in Minnesota, which has received about double its normal precipitation over the past 3 to 4 months, resulting in the 5th snowiest winter on record in Minneapolis. Snow depths are in excess of 20 inches over wide swaths of of the state, and this snow has a very high water content equivalent to 4 – 6 inches of rain. NWS is giving a 95% chance that the Mississippi River at St. Paul will exceed major flood stage this spring.

Wunder Blog : Weather Underground

North Dakota around Fargo is one of the flattest places on earth. This makes the extent of flooding and thus the area under risk notoriously difficult to predict.

Think of a “normal” topographic map, with contour lines nestled inside one another. Water flooding such a map will fill up along the contours.

Not so North Dakota. Outside the river valleys themselves, the contour lines are few and far between. Once water gets out of the valley, it goes everywhere.

And where does it break out? You can’t be sure of that either. The map you have probably does not show last year’s erosion, insignificant when the water follows more contoured terrain, but a serious breach in flood defense in the Dakotas.

 

 

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This entry was posted in Disasters, Earth Science, History, Science, Weather and tagged , , . Bookmark the permalink.

One Response to Red River Rising

  1. Beth Dale says:

    I live on the Minnesota River. Almost literally right on it as of this writing. It is swallowing up amazing amounts of land, closing roads and making a mess in my basement. Have admit, I’m really getting tired of it. Good luck with the Red River!

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