Red River and Devils Lake Basin - 2011 Spring Flood Outlook
Talking Points for 2/17/2011
This outlook is based on conditions as of 2/15/10, and will review subtleties which have occurred in the basins since 1/27/11 and any significant changes which are now present in the spring flood outlook.
There is some good news:
Warm temperatures this past week have helped to melt some of the existing snowpack and even to evaporate or sublimate some of the snowpack moisture, leading to a loss of from one tenth to one quarter of an inch of moisture.
So, overall net moisture gains since January have been quite low.
Our snowpack has become quite dense, compacted, and in some places soil is exposed.
1) Snow Water is still very high. The actual moisture from the snow is still present either in the dense snow, in the near soil layer, or in ditches – it has not gone away.
2) Soil Moisture is very high. Soils that were very wet last fall are still frozen and very saturated.
4) Wintery conditions are on the return, with a colder and snowier than normal pattern expected for the later part of February and beyond. With La Nina conditions expected to continue in the Pacific through early summer, an active weather pattern should persist well through the typical March-April snowmelt runoff period.
For the Southern Red River Basin: Precipitation here has been very close to normal through the past 3 weeks, and remains well above normal for the fall/winter period. There have been some subtle changes from the outlook risks released on 1/27/11 due to 1) snowfall received since 1/25/11, and 2) coordination with other agencies on issues involving reservoir releases plans and cross basin flows.
- Expected flows along the Sheyenne River downstream from Lake Astabula have been increased somewhat, so that the risk for 2009 scale flooding from Valley City to Lisbon has risen from about 10 percent to about 20 percent. Downstream of Lisbon, risks remain similar to those released in January, with flows expected very near 2009 levels.
- Near Fargo, the risk of 2010 scale flood [36.99 feet] has risen from 55 percent to about 70 percent. Fargo’s risk of exceeding the 2009 flood of record has risen to just over 20 percent.
- Otherwise, for remaining tributaries in the southern Red River Valley, mid-range risks are very near or only slightly higher than depicted in January.
For the Northern Red River Basin: Precipitation over the past 3 weeks has been near to slightly below normal here, and the winter snow pack has been running a bit above normal. Snowpack over northcentral Minnesota is running quite high.
- All points along the Red River have a better than 90 percent risk of major flooding.
- Fargo and Oslo both have a better than 20 percent risk of meeting or exceeding their 2009 floods of record. [in 2009 Fargo hit 40.84 ft, Oslo hit 38.19 ft]
- With mainstem Red River flows now expected to be slightly higher overall, the risk for 2009 scale flooding near Grand Forks has risen from about 60 percent to about 80 percent.
- The risk for reaching or exceeding the 1997 flood of record for both Halstad and Grand Forks remains roughly 10-12 percent. [in 1997 Halstad hit 40.74 ft, Grand Forks hit 54.35 ft]
- Hendrum, on the MN Wild Rice River, also stands a 20 percent risk of exceeding its 1997 flood of record (33.85 ft).
- Highlanding, The Red Lake River, has a better than 70 percent risk of breaking it’s 2009 flood of record (13.64 ft) largely due to high levels on the Red Lakes.
- Both Neche (Pembina River) and Grafton (Park River) should see levels near 2009. Grafton does have a 25 percent risk of exceeding its 1950 flood of record (16.52 ft).
For the Devils Lake Basin: This outlook still indicates that Devils Lake and Stump Lake will likely rise (80 percent probability) to a new record height in excess of 1454.25 ft elevation, and could rise (20 percent probability) to a height in excess of 1455.5 feet. Overall risk factors have dropped just slightly since January, largely due to below normal snowfall over the past 3 weeks. Through the winter months, both Devils Lake and Stump Lake have shown slight rises from their early December minimum. [Creel Bay gauge at 1451.69 on 2/16/11]