South Dakota State University
South Dakota Climate and Weather

15 MAY THROUGH 31 AUGUST 2007 SUMMER OUTLOOK

15 MAY THROUGH 31 AUGUST 2007 SUMMER OUTLOOK

SYNOPSIS
The climate prediction center is forecasting that neutral ocean temperatures across the central pacific ocean will become below normal by June. This means that La Nina conditions are expected to develop for the Summer of 2007. These forecast ocean conditions were compared with past summer seasons that produced similar ocean temperatures across the central pacific...and then the weather patterns were compared. These years were also examined for similar weather patterns in March and April. Finally...these data were used to predict the overall weather pattern for this upcoming summer.

We expect the general weather pattern to produce drier than normal weather beginning by the end of May and continuing through August. The best chance for precipitation to be near or above normal is expected to be across northwestern South Dakota. Temperatures are expected to be near normal to slightly above normal for the late May through August period.

TEMPERATURE OUTLOOK
At this time it appears that temperatures across northeastern Wyoming and western South Dakota will be near normal or slightly above normal from May through August. The best chance of above normal temperatures is expected to be across northeastern Wyoming.

PRECIPITATION OUTLOOK
At this time it appears that precipitation will be below normal across the region this summer...with the best chance of below normal rainfall in northeastern Wyoming.

Across northeastern Wyoming and the bear lodge mountains rainfall is expected to be 70 to 90 percent of normal. Precipitation for May through August averages 7 to 9 inches on the plains of northeastern Wyoming and 9 to 11 inches in the bear lodge mountains. Based on these conditions occurring...this would result in a 1.0 to 2.5 inch rainfall deficit on the plains and a 1.0 to 2.0 inch deficit in the bear Lodge Mountains.

In western South Dakota precipitation is expected to be 80 to 90 percent of normal. Precipitation for May through August averages 9 to 11 inches on the plains and 11 to 14 inches in the black hills. Based on these conditions occurring...this would result in a 1.0 to 3.0 inch rainfall deficit in the black hills and a 1.0 to 2.0 inch deficit on the plains.

May through August precipitation is 45 to 60 percent of the yearly rainfall. If the expected drier than normal conditions occur...rainfall deficits of 1 to 3 inches can be expected over the summer months. If this rainfall deficit occurs...then the current drought conditions would be expected to continue through the summer.

Source: http://www.crh.noaa.gov/unr/?n=2007_may-august_outlook
Ingested: 05/13/2007 4:00 pm CDT