September 2011 Climatic Summary

September temperatures averaged only 1 to 2 degrees above normal across the area. Above average temperatures were found across northeast Wyoming, northwest South Dakota, and the Black Hills area, with Gillette 4SE the warmest at 4.6 degrees above average. Below average temperatures occurred over central and southern South Dakota, with Winner being the coolest at 3.1 degrees below average.

It was a dry month in September for most locations. Precipitation averaged around 60 percent of normal across the area. The driest areas coincided with the areas that had above average temperatures, where precipitation averaged only 20 to 50 percent of normal. Hoover and Bison only recorded a trace of precipitation for the entire month. The wettest location was at Upton in northeast Wyoming, where precipitation was 177 percent of normal. The precipitation deficit for the month averaged a little more than 0.50 inches. No snowfall was reported in September. 

September storm summary...

September 1…An isolated severe thunderstorm produced quarter size hail in Rapid City.

September 2 & 3… Isolated severe thunderstorms produced quarter size hail in Wasta, and 9 miles southeast of Wall in Pennington County, and 19 miles southeast of Saint Francis in Todd County. Wind gusts to 60 mph were also reported in Interior in Jackson County.

September 19 &20…A very strong cold front moved through the northern plains the evening of the 19th and early morning hours of the 20th. Wind gusts of 50 to 70 mph were common across much of the area.

LOCAL EXTREMES Rapid City Lead Gillette
Temperature Temperature Date Temperature Date Temperature Date
Max. Temp. 92 degrees 11th 83 degrees 1st 93 degrees 1st
Min. Temp. 32 degrees 22nd 34 degrees 14th, 21st, 22nd 30 degrees  21st
Precipitation Rapid City Lead Gillette
Monthly Data Amount Date Amount Date Amount Date
Precipitation 0.75 inches   0.77 inches   0.99 inches  
Snowfall 0.0 inches   0.0 inches   0.0 inches  
Daily Data Amount Date Amount Date Amount Date
Max. Precipitation 0.29 inches 15th 0.46 inches 15th 0.59 inches 15th
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. 102 degrees Edgemont 1st 95 degrees Moorcroft 2nd
Min. Temp. 24 degrees Hill City 21st & 22nd 26 degrees Wright 12W 21st
Precipitation Western South Dakota Northeast Wyoming
Monthly Data Amount Site Date Amount Site Date
Max. Precipitation 1.65 inches Hot Springs   1.79 inches Upton  
Min. Precipitation Trace Bison & Hoover   0.26 Hulett  
Max. Snowfall 0.0 inches     0.0 inches    
Min. Snowfall 0.0 inches     0.0 inches    
Daily Data Amount Site Date Amount Site Date
Max. Precipitation 1.05 inches Interior 3 NE   1.34 inches Moorcroft  
Max. Snowfall 0.0 inches     0.0 inches    

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