Below is the updated 2011 Spring Flood Outlook
The following is the updated Advanced Hydrologic Prediction Services (AHPS) outlook based on conditions as of January 26 2011. Official textual and graphical outlook products are available at weather.gov/fgf and at devilslake.noaa.gov; a copy of the textual products is below.
The Red River Basin was previously updated on January 18 2011, while the Devils Lake Basin was last updated on December 23 2010. Below is a review of the subtleties which have occurred in these basins and any significant changes which are now present in the spring flood outlook.
A snapshot comparative: Snowfall totals from past winters November 1 - January 26th
Snowfall to date Following Spring Crest
Grand Forks Fargo Grand Forks Fargo
1996/97 57.1R 66.3R 54.35 39.57
2005/06 15.0 25.4 47.93 37.13
2008/09 36.0 42.5 49.34 40.84
2010/11 40.8 56.9
As of January 26th, Fargo is in 4th place for snowfall, UND/NWS Climate Station is in 5th place.*
A snapshot Comparative: Rainfall past fall and winters – totals September 1 - January 26th
Rainfall to date
Grand Forks Fargo
1996/97 6.30 10.57
2005/06 5.48 10.03
2008/09 13.18R 12.97R
2010/11 9.05 10.96
R = Record Values
As of January 26th, Fargo is in 5th place for the wettest fall & winter, while the UND/NWS Climate Station is the 7th wettest.*
* Preliminary figures, subject to final review and quality control
Current Conditions: 1) Wet to very wet soil conditions affected most of the area late last fall, into freeze-up. High to record base streamflows currently exist across most of the area. Rivers, lakes, and soil surfaces are frozen, but some subsoil drainage and flowing water conditions continue under the ice layers.
2) Above normal to well above normal snowfall rates have persisted across the Northern Plains throughout this winter season: - So far, Fargo ND has received 56.9 inches of snow, or 16.9 inches above its long term annual average for an entire winter season [compare: Fargo had 75.0” as of 1/26/97]. - Portions of west central MN, southeastern ND, and the Devils Lake Basin have also received much above normal snowfall. - Northern Red River Basin areas are running near to only slightly above normal for snowfall. So far, Grand Forks has received 33.4 inches of snowfall for the season. In comparison: Grand Forks had 68.6” as of January 26 1997
3) Climatologically, the current La Nina pattern is still expected to hold through the spring, which means we have the possibility of a colder and snowier winter plus the possibility of a cooler, stormier, and wetter spring. Thus excessive and residual rainfall in calendar year 2010, coupled with excessive winter snow to date, and with the prospects for a cool and wet spring to come means that we can expect major spring flood issues for many area lakes and rivers.
For the Southern Red River Basin: There have been some subtle changes from the outlook risks released on January 18 2011. These are based on
1) Additional snowfall received since January 13 2011, and;
2) Coordination with other agencies on issues involving cross-basin flows at high water levels. This means that the NWS and the U.S.Army Corps of Engineers have been working with other area agencies to better identify and model some of the breakout flow conditions that may be expected at the major to record flood levels we are expecting. Otherwise, current spring flood outlooks still indicate that much of the southern basin, including the Fargo-Moorhead area, already has a higher risk of spring flood levels than were seen in either the 2006 or 2010 major flood events. There persists a 20-25 percent chance that areas near Fargo-Moorhead could see flood levels approach the record levels set back in the early spring of 2009. Continued much above normal snowfall through the remainder of the winter will likely continue to drive that risk slightly upward in later outlooks.
The Otter Tail River sub-basin has seen especially high flows through this past summer and fall, with ice jam flooding still affecting some areas of Otter Tail and Wilkin Counties through the early winter.
The Buffalo, Bois de Sioux, Wild Rice (ND), and Sheyenne sub-basins are all freezing in (still some flow) at winter time record levels.
For the Northern Red River Basin: Probabilistic flood risks have increased slightly over most northern basin forecast points along the mainstem Red and its tributaries. These risks are similar to the risk of moderate to major spring flooding which was assessed in advance of the 2006, 2009 and 2010 major flood events, and there remains a roughly 10 percent risk of experiencing the record levels which occurred in the north basin back in 1997. With higher base streamflows and higher snow amounts than in 2010, most tributaries in the northern valley have a higher risk than last year of at least moderate flooding, especially the Roseau, Red Lake, and Pembina Rivers. As in 2009 and 2010, the northern basin had substantially lower snow amount and snow-water equivalent (SWE) amounts than in southern (Fargo) or western (Devils Lake) areas. Snowfall amounts in the north are running somewhat above normal for the current winter, and they are significantly higher than last year’s amounts. Likewise, summer-fall rainfall amounts were 5-8 inches above normal across the northern basin, but lower than southern basin amounts. Thus base stream flows are currently high, but below record levels.
For the Devils Lake Basin: This outlook now indicates that Devils Lake and Stump Lake have a 60 to 80 percent probability of rising to a new record height in excess of 1454.5 ft elevation, and a slightly lower probability (30 percent) to a height in excess of 1455.5 feet. These risk values are roughly one half of a foot higher than previously indicated. Note: Devils Lake and Stump Lake reached a new record height of 1452.1 feet late this past summer, but they have now frozen over at their highest level ever recorded, currently within a half a foot of the summertime record level. The Creel Bay gauge was at 1451.643 on January 27 2011.
Below are graphics showing the snow water content as of January 27 2011 compared to January 27 2009.
Climate outlook for the spring 2011 snow-melt. At this time a moderate La Niña is ongoing in the equatorial Pacific and is expected to continue through the spring months of 2011. So far this winter the more classic La Niña impacts have been evident across the Red River Valley and Devils Lake Basins. Above normal snowfall and generally below normal temperatures have been affecting the region since the start of the winter season. Based on outlooks from the Climate Prediction Center (CPC) as well as historical information during previous La Niña events, there is an enhanced risk for below normal temperatures to continue through the February, March and April time period. There is also an enhanced risk for above normal precipitation during the late winter and early spring months of March, April and May. Historical data suggests that La Niña springs see a slightly delayed warm up, with a risk for a more rapid rise in temperature in April than is climatologically normal. There is also an enhanced risk for significant rain or snow near the time of the melt.
The following is neither a forecast nor an outlook, but is provided as a historical reference of previous La Niña springs. On balance during an El Niño or ENSO neutral year the average date warm enough to initiate melting is near the end of March or the first few days of April. During years with a La Niña the average date with temperatures consistently warm enough to initiate snow-melt flooding is about 10 days later. While this example is for the Fargo area, it represents general conditions within the Red River Valley. As we get into the late winter and early spring additional risk assessments of potential La Niña impacts on the 2011 flood will be available.
For additional information please contact the National Weather Service in Grand Forks at 701.795.5198