15 May through 31 August 2010 Summer Outlook

Synopsis...
Near average oceanic temperatures were present across the central Pacific. The Climate Prediction Center forecasts these oceanic conditions to persist through the summer. These oceanic conditions, along with recent weather trends, were used to develop our prediction of the general weather pattern across the northern high plains for mid May through August.

Outlook...
We expect precipitation to be near or slightly above long term averages from mid May through August, with the best chances of above average precipitation from mid May through June. Temperatures are expected to be slightly below long term averages through the summer, with the best chances of near normal temperatures across northeastern Wyoming.

Impacts...
Across northeastern Wyoming and the Bear Lodge Mountains, rainfall is expected to be 100 to 120 percent of normal. Rainfall for May through August averages 7to 9 inches on the plains of northeastern Wyoming and 9 to 11 inches in the Bear Lodge Mountains. Based on our outlook, this could result in a 0.75 to 0.99 inch rainfall surplus on the plains, and a 0.90 to 1.21 inch surplus in the Bear Lodge Mountains. In western South Dakota, rainfall is expected to be 100 to 120percent of normal. Rainfall for May through August averages 9 to 11 inches on the plains and 11 to 14 inches in the Black Hills. Based on our outlook, this could result in a 1.10 to 1.54 inch rainfall surplus in the Black Hills, and a 0.90 to 1.21 inch surplus on the plains. Snowfall and rain from this past winter and spring have filled reservoirs and stock ponds across western South Dakota. If the anticipated rainfall for May through August occurs, then above average stream and river flows will continue.


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