May 2009 Climatic Summary

Temperatures in May were near average, with most areas ranging from 1 degree below average to 1 degree above average. Spearfish was the warm spot averaging 2.8 degrees above normal. Winner was the cold spot averaging 3.7 degrees below normal.

May was a dry month with precipitation averaging only 35 to 45 percent of normal. All locations reported below normal precipitation. The wettest areas were across northwest South Dakota where precipitation averaged 60 to 80 percent of normal. The driest areas were across central and south central South Dakota where precipitation was 10 to 20 percent of normal. The wet spots were at Hereford 12SSW and Wind Cave where precipitation was 95 percent of normal. Cottonwood was the dry spot with only 11percent of normal precipitation. The precipitation deficit for the month averaged 1.81 inches.
The only snow reported in May was 2 to 4 inches that fell over the higher elevations of the Black Hills and Bear Lodge Mountains.

May storm summary...

On May 12…a strong upper level disturbance brought severe weather to northwest South Dakota and to Crook and northern Campbell counties in northeast Wyoming.  There were numerous reports of Quarter size hail and wind gusts to 60 mph over this area. An F1 tornado was reported 5 miles west of Dupree in Ziebach County. The largest hail reported was 1.5 inches in diameter and fell 21 miles north of Hulett in Crook County.

On May 13…strong northwest winds developed behind a cold front producing winds of 30 to 40 mph with gusts to around 60 mph across western South Dakota. The strongest wind gusts reported were 61 mph at Buffalo and Faith.

On May 24…A strong upper level disturbance brought heavy rains to northeast Wyoming and portions of far western South Dakota. Across northeast Wyoming rainfall was generally 0.25 to 0.50 inches. A band of heavier rain fell between Newcastle and Sundance where 1.00 to 1.50 inches of rainfall was reported along with some minor stream flooding.  In western South Dakota rain fell from far southwestern areas north through the Southern and Central Black Hills and along the eastern foothills. The heaviest rains were from Hot Springs to Rapid City were 1.00 to 2.00 inches of rain fell, causing some minor street and stream flooding. The heaviest rain was reported at the NWS in Rapid City where 2.17 inches of rain fell.

On May 30…An isolated severe thunderstorm dropped golf ball size hail on Moorcroft in Crook County.

On May 31…Scattered thunderstorms brought some severe weather to southwest and south central South Dakota. Hail to the size of quarters was reported near Buffalo Gap and Maverick Junction in Fall River County, Slim Butte in Shannon County and Clearfield in Tripp County.  


 LOCAL EXTREMES

Temperature Data

Rapid City

 

Lead

 

Gillette

 

 

Temperature

Date

Temperature

Date

Temperature 

Date

Maximum Temperature

94 degrees

19th

87 degrees

19th

92 degrees

19th

Minimum Temperature

24 degrees

16th

25 degrees

4th

23 degrees

2nd

Precipitation Data

Rapid City

 

Lead

 

Gillette

 

Monthly Data

Amount

Data

Amount

Date

Amount

Date

Precipitation

0.94 inches

 

2.20 inches

 

0.64 inches

 

Snowfall

0.0 inches

 

2.2 inches

 

0.0 inches

 

 

 

 

 

 

 

 

Daily Data

 

 

 

 

 

 

Maximum Precipitation

0.53 inches 

24th

0.51 inches

8th

0.30 inches

8th

Maximum Snowfall

0.0 inches

 

2.2 inches

8th

0.0 inches

 

REGIONAL EXTREMES 

Temperature Data

 

Western South Dakota

 

 

Northeastern Wyoming

 

 

Temperature

Site

Date

Temperature

Site

Date

Maximum Temperature

100 degrees

Cedar Butte 1NE
Porcupine 
11N

20th

95 degrees

Newcastle

20th

Minimum Temperature

21 degrees

Pactola Dam

2nd

 21 degrees   21 degrees

Devils Tower   Upton 14ENE

2nd
1st

Precipitation Data

 

Western South Dakota

 

 

Northeastern Wyoming

 

Monthly Data

Amount

Site

Date

Amount

Site

Date

Maximum Precipitation

3.01 inches

Wind Cave

 

1.61 inches

Sundance

 

Minimum Precipitation

0.31 inches

Cottonwood 2E

 

0.50 inches

Upton

 

Maximum Snowfall

4.0 inches

Custer

 

2.0 inches

Upton 14ENE

 

Minimum Snowfall

0.0 inches

 

 

0.0 inches

 

 

 

 

 

 

 

 

 

Daily Data

 

 

 

 

 

 

Maximum Precipitation

2.17 inches

WFO Rapid City

24th

0.87 inches

Upton 14ENE

25th

Maximum Snowfall

4.0 inches

Custer

1st

2.0 inches

Upton 14ENE

8th

 MONTHLY RECORDS

LOCATION

DATE

NEW RECORD

OLD RECORD

DATE

 

 

NO RECORDS SET

 

 


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