2012 Annual Climatic and Hydrologic Summary for Western South Dakota and Northeastern Wyoming
 
 
Temperature and Precipitation Summary
 
Temperatures averaged 3.3 degrees above normal across the entire region for the year. Every month during 2012 was above average except for October, which was only 1.4 degrees below average. The month with the highest departure was March, which was over 12 degrees above average across the region. It was the warmest March on record for many locations. Camp Crook and Milesville were the warmest locations for the year, averaging 3.9 degrees above normal. The coolest location was Wood in south central South Dakota, where temperatures averaged only 2.8 degrees above normal.
 
Precipitation averaged only 70 percent of normal across the entire region, with the average deficit being 5.50 inches. Early spring fluctuated wildly in 2012. February was wet with 148 percent of normal precipitation. Then March came through with only 24 percent of normal precipitation. April was back above average at 114 percent of normal. The highest annual precipitation total was at Lead, where 21.86 inches of precipitation fell. Wright 12W was the driest location, with only 8.71 inches. The wettest location by percentage was Camp Crook, receiving 86 percent of normal precipitation (11.68 inches). The driest location by percentage was Ft. Meade, receiving only 51 percent of their yearly average precipitation (10.72 inches).
 
Snowfall averaged only 55 percent of normal across the entire region, with the average deficit being 20 inches. The snowiest month was February, with most locations receiving 100 to 130 percent of their normal snowfall totals. With the above average temperatures in March and April, snowfall was essentially non-existent. The warmer and drier conditions in the Fall and early Winter kept snowfall below average also. The highest annual snowfall total was at Lead, where 112 inches fell. Cottonwood had the least amount of snow, with only 10 inches for the year. The snowiest location by percentage was Interior, receiving 70 percent of normal snowfall (19.7 inches). The location with the least amount of snow by percentage was Mt. Rushmore, receiving only 72 percent of their average yearly snowfall (14.0 inches).
 
 
 
2012 Notable Weather Events
 
Drought Returns: Following a year of abundant moisture in 2011, precipitation was considerably less in 2012. Weather observing stations across the Black Hills region received only 50 to 85 percent of annual moisture, after most measured above normal precipitation last year. Very little snow fell in March, normally the snowiest month of the year. Sixteen locations set records for the driest March while 19 stations set records for lowest snowfall. The entire summer season was drier than normal, and Fort Meade/Sturgis and Winner had their driest summers on record. Many sites did not receive any precipitation for the entire month of September. By the end of 2012, most of the region was in extreme to exceptional drought—the worst two categories—and the rest of the region in severe drought.
 
A VERY Warm Year: 2012 was one of the warmest years on record for the Black Hills region. Average temperatures for many locations finished near or just above the previous records; most of which were established in 2006, 1987, and 1934. Four stations set monthly high temperatures the first week of January, and both the Rapid City Airport and the NWS office recorded their earliest 70 degree high temperature on January 5. Twenty stations had the warmest March on record, with many daily records set. Summer was one of the warmest seasons in the Black Hills region; rivaling the summers of 2006, 1988, and 1936. Mission 14S, Gillette 4SE, and Newcastle recorded their highest average summer temperatures. Numerous daily and several monthly high temperature records were set when temperatures soared above 100 degrees on June 26 and August 29.
 
 
Wildfires: Warm, dry, and occasionally windy conditions led to a very active fire season, which began early in the spring and lasted well into fall; and prompted local officials to issue drought disaster declarations, burn bans, and cancel Independence Day fireworks. With no snow on the ground in March, several fires grew rapidly through last year’s tall dead grass, including two inside the Rapid City city-limits. Lightning from dry thunderstorms ignited several large fires during the summer.
 
 
October Winds: An intense storm system tracking across the northern tier of the United States produced very strong wind gusts over the Black Hills region October 17 and 18. Gusty northwest winds increased behind a cold front during the early morning of October 17, with a gust reaching 73 mph near Parmelee on the Rosebud Indian Reservation. A gust of 81 mph was recorded at the National Weather Service office in Rapid City on October 18.
 
 
Severe Thunderstorms: Only two tornadoes were verified during 2012. A large tornado moved across pastures in southern Fall River County June 22. It destroyed a barn and several sheds on a ranch north of Ardmore. A small tornado touched down briefly and snapped trees in the southern Black Hills between Pringle and Hot Springs on June 7.
 
More damage was caused by straight line thunderstorm winds than hail. Winds estimated at 90 mph blew roofs off buildings along Kadoka’s Main Street on May 18. Several bands of thunderstorms crossed the western South Dakota plains the evening of June 9. Strong winds and large hail beat crops north of Wall; overturned two semi-trailer trucks near Philip; and destroyed barns, sheds, and corrals southeast of Dupree. On July 21; two mobile homes were rolled and completely destroyed, a stick-built house lost a large portion of its roof, and several other houses were damaged by downburst winds near Oglala. A windstorm damaged buildings from Hot Springs to Buffalo Gap on July 23, while another storm caused damage in Newell the same night.
 
The largest hail reported was also the season’s first severe thunderstorm when softball sized hail (4 1/4 inches in diameter) fell south of Mission on March 18. Another report of softball sized hail came from southwest of Edgemont on June 22. The strongest thunderstorm wind gust recorded was 90 mph at the Belle Fourche Airport on July 5, which blew the door off a hangar.
 
 
Few Winter Storms: A winter storm brought snow to much of the northern Plains and upper Midwest February 28-29. Most areas received only two to five inches of snow, and part of northwestern South Dakota, the northern Black Hills, and northern Tripp County measured six inches or more. The highest snowfall report was 10.5 inches south of Lemmon. No major winter storms occurred during the fall and early winter, although two small systems produced localized heavy snow. The season's first measurable snow was on October 5. Two to six inches of snow fell across northeastern Wyoming and the southern Black Hills, with a small area of eight to ten inches reported north of Custer. A narrow band of snow developed over northeastern Wyoming and moved across northwestern South Dakota December 6-7. Meade County received four to eight inches of snow during the night, with a report of ten inches near Marcus.
 
 
2012 Flooding Summary
 
A rather mild winter limited flooding in January and February. However in March, unseasonably warm temperatures melted snow and combined with ice break-up to cause minor flooding along the Belle Fourche River and its tributaries in Crook County, WY.  Minor flooding of agricultural land occurred and big pieces of ice were deposited along Highway 14 near Carlile, WY. After the ice went out in the rivers, drought conditions began to worsen. No flooding was reported in April, May, or June.

In July, two flash floods occurred, with both of them occurring in burn areas. On July 5, slow moving thunderstorms with heavy rain and strong winds moved across the White Draw Fire northeast of Edgemont, SD. Water containing silt and debris was reported flowing over a few gravel roads and fire lines with minor surface erosion caused by the runoff. Dry drainage areas quickly filled with flowing water 1 to 2 feet deep. On July 17, flash flooding occurred in Black Canyon located within the Oil Creek Fire Burn Area northwest of Newcastle, WY. Runoff from ¾” of rain in 20 minutes caused debris to be carried several miles down the canyon. Debris covered Seeley Road in numerous locations, corrals at the Seeley Ranch were destroyed, and three stock ponds were completely silted in due to the flash flood debris flows.

Severe to exceptional drought conditions expanded across the area during the late summer and fall months, with limited rainfall amounts. No reports of flooding were received for the rest of 2012.
 
 
 
 
 
2012 Temperature Extremes
 
Station
High
Date(s)
Low
Date
Buffalo*
111
June 26
-12
February 11
Cottonwood
111
July 19, Aug 29
-18
Jan 17, Feb 11 & 12
Faith
107
July 19
-10
January 19
Gillette
107
June 24
-7
January 17
Interior
109
August 29
-10
February 11
Pine Ridge *
107
July 19 & 20
-17
December 28
Philip *
111
July 19, August 29
-15
February 11
Rapid City Airport *
109
June 26
-8
February 11
Winner
112
August 29
-3
February 12 & 13
 
 
 
2012 Precipitation Extremes
 
Station
Rainfall
Date(s)
Snowfall
Date(s)
Buffalo *
1.00
July 17
Not Available
Not Available
Cottonwood
2.80
June 8
3.2
February 29
Faith
0.99
June 7
3.8
February 29
Gillette
1.17
July 6
5.0
February 22
Interior
2.18
June 8
3.0
February 29
Pine Ridge *
1.39
April 15
Not Available
Not Available
Philip *
0.77
April 15
Not Available
Not Available
Rapid City Airport
0.90
April 14
2.4
December 24
Winner
1.76
June 20
4.0
March 1
 
 
* Data is from the automated weather station

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