Drought Conditions Continue Across Western South Dakota and Northeastern Wyoming

Updated on Thursday, April 19, 2007
Next Scheduled Update by Friday, May 18, 2007

Summary

Temperatures were very warm through the last half of March. However, a large upper level storm system arrived during the last 3 days of March which brought below normal temperatures and above normal precipitation. These below average temperatures persisted into the middle of April while precipitation amounts stayed close to normal.

Local Area Affected

Drought conditions as of April 19, the majority of western South Dakota was classified as being in severe (D2) drought conditions with the exception of the extreme southwestern corner which remains in extreme (D3) drought and the northern Black Hills which is classified as moderate (D1) drought. Drought conditions have improved to moderate (D1) drought over Ziebach, Haakon, Jackson and Bennett counties and to the abnormally dry category (D0) over Mellette, Todd and Tripp counties. Northeastern Wyoming remains in the moderate (D1) drought classification.

Climate Summary

Temperatures were well above average in March across western South Dakota and slightly above average in northeastern Wyoming. It was the second warmest March on record for Rapid City. Temperatures averaged 6 to 10 degrees above normal across western South Dakota and 1 to 2 degrees above normal in northeastern Wyoming. Through March 27, precipitation was well below average. A large upper level storm system on March 28 and 29 dropped heavy rain and snow across the area. After this storm, March precipitation ended the month on average 30 to 50 percent above average.

Precipitation averaged 2.25 to 3.25 inches on the plains of northeastern Wyoming...in the Northern Black Hills and in the Bear Lodge Mountains. On the plains of western South Dakota, precipitation averaged 1.25 to 2.25 inches. The only exception was over southwestern South Dakota and on the plains immediately east of the Black Hills from Rapid City south. These areas only reported 0.75 to 1.25 inches of precipitation, which is near average.

Temperatures so far in April have been 4 to 8 degrees below average. Precipitation so far has been near average.

River and Reservoir Conditions

According to the United States Geological Survey (USGS), most stream flows across the area are between the 10th and 74th percentile.

Reservoirs around the region remain well below capacity. The table below shows reservoir percent of normal capacity and change in elevation over the past 30 days as calculated by the United States Bureau of Reclamation (USBR).

Reservoir Percent of Normal Elevation Change
Angostura 44% +0.6 ft
Belle Fourche 55% +2.5 ft
Deerfield 79% +1.0 ft
Keyhole 32% +0.8 ft
Pactola 60% +1.5 ft
Shadehill 63% +0.4 ft

Temperature and Precipiation Outlook

Neutral ENSO (El Nino–Southern Oscillation) conditions continued into April. At this time, La Nina conditions are expected to develop for the May through July time period. There is a lot of uncertainty on how strong the La Nina will be. The outlook through May calls for above average temperatures and near to below average precipitation.

Questions or Comments

If you have any questions or comments about this drought information please contact,

Melissa Smith or Lee Czepyha
Drought Focal Points
National Weather Service
300 East Signal Drive
Rapid City South Dakota 57701
Telephone 605-341-9271
E-mail melissa.smith@noaa.gov or lee.czepyha@noaa.gov

Acknowledgements

The drought monitor is a multi-agency effort involving NOAA's National Weather Service (NWS) and National Climatic Data Center, the United States Department of Agriculture (USDA), state and regional center climatologists, and the National Drought Mitigation Center. Information for this statement has been gathered from NWS and Federal Aviation Administration observation sites, state cooperative extension services, USDA, USBR, and USGS.


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