Spring thaw progress for Red River of the North

Recent snows that fell over the Red River Valley have replenished the snow pack, especially south of an interstate 94 and U.S. Highway 10 line. Snowfall varied from 4 to 10 inches across Cass, Richland, Sargent over into Wilkin and Ottertail counties. Over the past week, air temperatures have dropped to below freezing which has shut down the snow melt. Some additional Snow Water Equivalent (SWE) has been added to the southern basin of the Red River of the North during the Presidents Day weekend storm, with about an inch to the sub-basin contributing to Lake Traverse and to the western Wild Rice River in North Dakota.

There existed a strong SWE gradient from north to south across Sargent and Richland counties of southeast North Dakota. New SWE ranged from one inch or more near the Dakotas border to a tenth to a quarter inch in northern Richland and Sargent counties. Teams from the North Dakota State Water Commission and USGS will perform additional SWE surveys in the coming week to assess the current snow pack in the southern Valley.

In response to the recent cold weather the snow-pack temperatures have again cooled. Temperatures in the snow-pack have fallen from near freezing last week back to the single digits above zero in many areas. This has stopped any snow-melt. What little snow did melt last week was mostly captured in the soil and local drainage with only small amounts actually making it into the river system.

The most significant impact to the warming snow-pack last week was a process known as ripening. This ripening sets the stage for a more rapid melt of the existing snow-pack when the true spring snow melt begins sometime within the next several weeks. The longer term weather outlook, which goes through March 9th calls for below normal temperatures and above normal precipitation into the first full week of March. Generally below normal temperatures, with some risk for continued above normal precipitation, can be expected for much of March 2011.

At this time it is not possible to predict exactly when the start of the [actual] 2011 spring melt will begin. Historically this would occur in late March over the southern Red River Valley, spreading north during the first week of April. The NWS office in Grand Forks will be closely monitoring the weather for the first signs of the spring snow melt and inform you on the onset and timing of the thaw. Refer to the spring flood outlooks for more specific information on the chances of flooding on the Red River of the North as well as our Minnesota and North Dakota tributaries. These spring flood and water resources outlooks are issued several times during the critical spring melt period, usually from early March to early April depending on conditions.

The outlooks are presented as text products and graphs for the chance of reaching or exceeding minor, moderate and major flood stages. In addition probabilities that the river will reach or exceed the stages given for river locations are provided for the full outlook periods and for weekly intervals during the period. These graphs, text products and explanations that help interpreting them are available from the NWS Grand Forks AHPS web page on the Internet at:

www.weather.gov/grandforks

 click on the "Rivers and Lakes AHPS" tab above the map or the link in the menu on the left side of the web page. Current river conditions for all river forecast points in the Red River of the North and Devils/Stump Lake basin conditions are also available on our web site as well as the 7-day forecasts when the river at the forecast point is in or near flood.

If you have any questions please contact the NWS at 701-772-0720.

Snow  Water Content Comparison. Click for larger image

Image of the change in SWE due to the Presidents Day Weekend storm.



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