September 2006 Climatic Summary

 An upper level trough of low pressure moved across the region as September began and brought cool weather and some light rain for the first 4 days. High pressure then pushed into the region with mainly dry weather and seasonal temperatures for September 5 through 7. An isolated severe thunderstorm produced large hail in Custer on September 6. An upper level trough brought cooler temperatures to the region from September 8 through 10. High pressure returned and brought dry and warm weather from September 11 through 14. Another upper level trough moved across the region with cooler temperatures and scattered showers and a few thunderstorms from September 15 through 18. High pressure brought dry and warm temperatures for September 19 and 20. On September 21 a powerful upper level low pressure system brought much colder temperatures and heavy rains from September 21 through 24. On the plains of northeastern Wyoming and western South Dakota 1.25 to 2.50 inches of rainfall was common. In the northern Black Hills 4 to 6 inches of rain fell…with snow above 6000 feet. Terry Peak and O’Neil Pass both reported 10 inches of snow from this storm. High pressure built over the region from September 25 through the end of the month…bringing warm temperatures and dry weather.

Temperatures were below normal in September. Temperatures across northeastern Wyoming and the Black Hills averaged 1.5 to 3 degrees below normal…while on the South Dakota plains temperatures averaged 3.0 to 5.0 degrees below normal. Averages ranged from 1.1 degrees below normal at Spearfish to 7.0 degrees below normal at Wood.

September was a wet month across most of western South Dakota and northeastern Wyoming. The only areas to record below normal precipitation were the southern Black Hills…southwestern South Dakota and the southern half of Weston county in northeastern Wyoming. Precipitation in these areas averaged 80 to 100 percent of normal. Elsewhere, September was quite wet with average precipitation 200 to 300 percent of normal. Precipitation ranged from 366 percent of normal at Deadwood 2NE to 45 percent of normal at Hot Springs.

LOCAL EXTREMES

Temperature Data

Rapid City

 

Lead

 

Gillette

 

 

Temperature

Date

Temperature

Date

Temperature 

Date

Maximum Temperature

92 degrees

13th, 14th

84 degrees

13th

91 degrees

12th, 13th

Minimum Temperature

30 degrees

19th

28 degrees

18th

32 degrees

16th, 18th

Precipitation Data

Rapid City

 

Lead

 

Gillette

 

Monthly  Data

Amount

Data

Amount

Date

Amount

Date

Precipitation

2.00 inches

 

6.77 inches

 

2.45 inches

 

Snowfall

0.0 inches

 

1.5 inches

 

0.0 inches

 

 

 

 

 

 

 

 

Daily Data

 

 

 

 

 

 

Maximum Precipitation

0.87 inches

22nd

2.87 inches

22nd

1.10 inches

22nd

Maximum Snowfall

0.0 inches

 

1.5 inches

18th

0.0 inches

 

REGIONAL EXTREMES

Temperature Data

 

Western South Dakota

 

 

Northeastern Wyoming

 

 

Temperature

Site

Date

Temperature

Site

Date

Maximum Temperature

99 degrees

Ardmore 2N    Cottonwood 2E

14th                15th

94 degrees

Weston 1E

13th

Minimum Temperature

21 degrees

Medicine Mtn.

28th,  29th

24 degrees

Upton 14ENE

28th

Precipitation Data

 

Western South Dakota

 

 

Northeastern Wyoming

 

Monthly Data

Amount

Site

Date

Amount

Site

Date

Maximum Precipitation

7.36 inches

Deadwood 2NE

 

4.18 inches

Devil's Tower

 

Minimum Precipitation

0.32 inches

Edgemont 23NNW

 

0.59 inches

Newcastle

 

Maximum Snowfall

3.2 inches

Deadwood 2NE

 

1.5 inches

Upton 14ENE

 

Minimum Snowfall

0.0 inches

Several locations

 

0.0 inches

Several locations

 

 

 

 

 

 

 

 

Daily Data

 

 

 

 

 

 

Maximum Precipitation

3.62 inches

Deadwood 2NE

22nd

1.70 inches

Hulett

23rd

Maximum Snowfall

3.1 inches

Deadwood 2NE

18th

1.5 inches

Upton 14ENE

18th

MONTHLY RECORDS

LOCATION

DATE

NEW RECORD

OLD RECORD

DATE

Lead

September

6.77 inches rainfall

5.40 inches

2002

Bison

9/22/2006

1.94 inches rainfall

1.94 inches

9/18/1996

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