August 2011 Climatic Summary

August temperatures were warm, averaging 1 to 3 degrees above normal across the area. Well above average temperatures were found across northeast Wyoming and the Black Hills area, with Gillette 4SE the warmest at 4.5 degrees above average. Slightly below average temperatures occurred over far south central South Dakota, with Winner being the coolest at 1.3 degrees below average.

Precipitation in August averaged 20 to 30 percent above normal across the area. The wettest areas were across northwest and west central South Dakota where precipitation averaged 150 to 200 percent of normal. The driest areas were across southern South Dakota where precipitation was 50 to 100 percent of normal. The wettest location was Bison in northwest South Dakota, where precipitation was 285 percent of normal. Mission was the driest, with only 36 percent of normal precipitation. The precipitation surplus for the month averaged 0.40 inches. No snowfall was reported in August.
 
 
August storm summary...
 
August 1…A strong upper level disturbance brought large hail and damaging winds to northwest South Dakota. The largest hail reported was 3.0 inches in diameter 10 miles southeast of Hoover. Baseball size hail was reported 5 miles north of Dupree. There were numerous reports of winds in excess of 60 mph. The strongest wind gusts reported were 80 mph, 5 miles north of Dupree and 3 miles northeast of Red Elm, both in Ziebach County, and at Hoover in Meade County.
 
August 5…A strong upper level disturbance brought large hail and damaging winds to northeast Wyoming and western South Dakota. The largest hail reported in northeast Wyoming was the size of quarters, 14 miles north of Weston in Campbell County and 9 miles north of Oshoto in Crook County. In western South Dakota the largest hail reported was 1.5 inches in diameter, 2 miles southwest of Hermosa in Custer County, 18 miles north of Belle Fourche in Butte County, and at Hayward in Pennington County. The strongest winds reported were 85 mph, 7 miles south of Meadow in Perkins County and 70 mph, 11 miles southwest of Milesville in Haakon County.
 
August 7…A strong upper level disturbance brought widespread severe weather to western South Dakota. There were numerous reports of large hail, 1.5 inches in diameter or greater. The largest hail reported was the size of baseballs, 4 miles east of Rockerville in Pennington County. In downtown Belle Fourche hail 2.5 inches in diameter was reported. There were numerous reports of winds of 60 mph or more, with the strongest gust of 65 mph, reported near Vetal in Bennett County.
 
August 9…An isolated severe thunderstorm produced quarter size hail and 60 mph winds, 10 miles southeast of Wright in Campbell County, and quarter size hail 3 miles east of Rochelle in Weston County.
  
August 10…Isolated severe thunderstorms produced golf ball size hail and 60 mph winds, 5 miles west of Vetal in Bennett County, and quarter size hail 1 mile east of Hayward in Pennington County.
 
August 11…Scattered severe thunderstorms over western South Dakota produced baseball size hail, 6 miles northwest of Milesville and 2.0 in diameter hail 4 miles south of Milesville, both in Haakon County. These storms also produced 70 mph winds, 10 miles north of Wood in Mellette County. An isolated severe thunderstorm produced 60 mph winds, 25 miles north of Weston in Campbell County in northeast Wyoming.
 
August 14…Isolated severe thunderstorms produced 1.25 inch diameter hail, 2 miles northeast of Deadwood, and quarter size hail in Black Hawk, in Meade County.
 
August 15...Isolated severe thunderstorms produced 60 mph winds, 17 miles north of Recluse in Campbell County in northeast Wyoming, and 77 mph winds, 1 mile north of Buffalo in Harding County.
 
August 17…A strong upper level disturbance brought widespread severe weather to south central South Dakota where there were numerous reports of large hail. The largest hail reported was the size of baseballs, 8 miles northeast of Belvidere in Jackson County
and 15 miles north of Cedar Butte in Mellette County. A wind gust to 60 mph was also reported 1 mile west of Keyapaha in Tripp County.
 
August 18…Scattered severe thunderstorms brought large hail to southwest and south central South Dakota. The largest hail reported was the size of baseballs near Allen in Bennett County and 6 miles northwest of Kyle in Shannon County.
 
August 25…An isolated severe thunderstorm produced 68 mph winds 5 miles northeast of Porcupine in Shannon County. 

August 27…An isolated severe thunderstorm produced quarter size hail at Pactola Reservoir and golf ball size hail 4 miles north of Hermosa, both in Pennington County.

August 29…An isolated severe thunderstorm produced large hail and damaging winds across northern Campbell County in northeast Wyoming. The largest hail reported was the size of half dollars, 13 miles southwest of Weston, with 58 mph winds being reported 5 miles north of Gillette. Another isolated severe thunderstorm produced half dollar size hail, 14 miles southwest of Provo in Fall River County.

LOCAL EXTREMES Rapid City Lead Gillette
Temperature Temperature Date Temperature Date Temperature Date
Max. Temp. 101 degrees 25th 93 degrees 25th 100 degrees 25th & 26th
Min. Temp. 50 degrees 13th 46 degrees 14th, 15th, 16th 44 degrees 14th
Precipitation Rapid City Lead Gillette
Monthly Data Amount Date Amount Date Amount Date
Precipitation 1.75 inches   2.33 inches   1.45 inches  
Snowfall 0.0 inches   0.0 inches   0.0 inches  
Daily Data Amount Date Amount Date Amount Date
Max. Precipitation 1.07 inches 29th 1.03 inches 3rd 0.42 inches 30th
Max. Snowfall 0.0 inches   0.0 inches   0.0 inches  
             
REGIONAL EXTREMES Western South Dakota Northeast Wyoming
Temperature Temperature Site Date Temperature Site Date
Max. Temp. 106 degrees Oral 1st 101 degrees Hulett 1st
Min. Temp. 42 degrees Pactola Dam 13th 38 degrees Upton 14 ENE 9th
Precipitation Western South Dakota Northeast Wyoming
Monthly Data Amount Site Date Amount Site Date
Max. Precipitation 4.59 inches Custer   1.93 inches Upton 14 ENE  
Min. Precipitation 0.76 inches Mission   0.95 inches Dillinger  
Max. Snowfall none     none    
Min. Snowfall none     none    
Daily Data Amount Site Date Amount Site Date
Max. Precipitation 1.90 inches Custer 4th 1.04 inches Moorcroft 4th
Max. Snowfall none     none    

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