SIOUX FALLS AREA
CLIMATIC SUMMARY
2006

By Richard Ryrholm
Climatic Focal Point
National Weather Service, Sioux Falls

...ANOTHER WARM YEAR...BUT INCONSISTENT PRECIPITATION AT SIOUX FALLS IN 2006...

Temperatures averaged out to a mild 48.5 degrees in 2006, or 3.4 degrees above the normal of 45.1 degrees. It was the 8th warmest year since records began at Sioux Falls in 1893, and also the 9th straight year of above normal temperatures. The last below normal year was 1997 with an average temperature of 43.8 degrees. Precipitation totaled a healthy 26.74 inches in 2006, or 2.05 inches above average. However, the precipitation pattern was rather inconsistent, especially during the critical growing season from May through July, when drought intruded into the area from the west. Fortunately, good rains before and after this three month period helped to alleviate drought conditions.

2006 started off very mild for the winter season, which has become more normal in the last 20 years. As a matter of fact, it was by far the warmest January on record, averaging 31.1 degrees or a whopping 17.1 degrees above normal. This smashed the old record of 28.2 degrees set in 1990. Because of the record warm January, the meteorological winter season of December 2005 through February 2006 averaged 24.1 degrees for the 10th warmest winter on record. This makes 4 out of the last 8 winters in the top ten warmest winters in 113 years of records, or 40% of the top warmest winters occurring in the most recent 7% of our climatic history. If you also include the top warmest winters of 1986/87 and 1991/92, this makes 60% of the top ten warmest winters occurring in the most recent 17% of our climatic records. The warmest winter on record is still 28.7 degrees in the 1930/31 winter. 

For 52 consecutive days from December 21, 2005 through February 10, 2006, the daily maximum temperature was at least 28 degrees. This beat the old meteorological winter record of 39 straight days in a row from January 21st through February 28th in 1931. There was a similar record streak for mild low temperatures this last winter, with 45 straight days with minimums of at least 10 degrees from December 22nd through February 4th.

Little happened in February, except for the lowest temperature of the year of 11 below zero registered on the 18th, helped by only one inch of snow on the ground, which was the maximum snow depth for the whole month. March saw a return to more normal conditions, with the last hurrah of winter producing a March total of 9.3 inches snowfall from the 12th to the 21st. The heaviest 24 hour snowfall of the year of 6.7 inches occurred the 12-13th.

From March 30th through the month of April it was very wet but mild, with a total of 7.74 inches rainfall. It was the second wettest April on record with 6.17 inches. This was largely due to the biggest precipitation event of the year of 3.39 inches on April 6-7th, mostly occurring between 10 PM and 5 AM CDT. This heavy rain event, with up to 6 inches reported just north of the city, caused the only notable urban and river flooding of the year in the area. 

May all of a sudden turned dry, and except for crop-saving rains in the third week of June, it would have been the driest May through July period ever. It tied for the 8th driest May with 1.02 inches, and July tied for the 9th driest with only 0.68 inch of rain. The second biggest 24 hour precipitation event of 2006 of 1.93 inches occurred June 16-17th. The wet third week of June 2006 with 3.01 inches rain from June 16th to the 23rd was a welcome oasis in the midst of a desert like growing season. There was severe weather in the area at this time, with large hail up to golf ball size destroying crops in a swath from Turner into Lincoln counties from 400 to 430 PM on June 16th. Also hail up to 1 inch diameter was reported in Sioux Falls around 3 AM on June 20th. Hail up to 1 inch diameter and thunderstorm wind gusts up to 70 mph were reported northwest to southwest of Sioux Falls from near Madison to Tea in the late afternoon of July 24th. On July 30th, near the end of the dry period, the yearly high temperature of 100 degrees was recorded, which was the first time since July 20, 2002 that Sioux Falls officially recorded 100 degrees or more.

Then the first of August commenced a two month wet period with August to September precipitation totaling 2.62 inches above normal. A significant severe weather event hit eastern Turner and a good part of Lincoln County in the early afternoon of August 18th. Thunderstorm winds estimated around 90 mph caused widespread and severe tree, power line, and crop damage. In addition, heavy rain up to 5 inches caused flash flooding, mainly from Tea to Harrisburg. In September, in the afternoon of the 16th, a number of tornadoes along with large hail affected a swath from west through north of Sioux Falls. The two most significant tornadoes were an F2 tornado that damaged 3 farms from just north of Bridgewater to 5 miles east of Salem in McCook County, and an F1 tornado that caused damage in northwest Minnehaha County to the northeast of Colton between 4 and 5 PM.
 
September and October were also the only months of the year below normal in temperature, but November and December bounced back to much above normal temperatures. A sign of abnormally mild winters recently is that 1.78 inches of the 5th wettest and 9th warmest December on record was from rain, not snow. Only 4.1 inches snowfall has occurred at Sioux Falls so far in the 2006/07 season, but the snow season has a long way to go...

THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 2006 AT THE SIOUX FALLS AIRPORT...

TEMPERATURES

                 AVERAGE             DEPARTURE  EXTREMES    MONTHLY
MONTH MAX MIN MONTHLY FROM NORM HIGH LOW RECORDS

JANUARY 38.2 24.0 31.1 PLUS 17.1 57 14 1ST WARMEST
FEBRUARY 33.7 12.8 23.3 PLUS 2.5 57 11B
MARCH 42.2 24.4 33.3 PLUS 0.7 63 4
APRIL 62.6 41.0 51.8 PLUS 6.1 87 25 2ND WETTEST
MAY 71.7 47.4 59.6 PLUS 1.8 94 34 8TH DRIEST
JUNE 81.3 56.7 69.0 PLUS 1.5 89 42
JULY 88.7 63.2 76.0 PLUS 3.0 100 49 9TH DRIEST
AUGUST 81.6 61.0 71.3 PLUS 0.5 90 48
SEPTEMBER 68.5 47.8 58.1 MINUS 2.8 86 30
OCTOBER 58.3 34.4 46.3 MINUS 1.7 88 16
NOVEMBER 47.0 21.7 34.3 PLUS 3.0 77 4
DECEMBER 37.9 18.4 28.1 PLUS 9.8 56 4B 5TH WETTEST

2006 59.3 37.7 48.5 PLUS 3.4 100 11B
NORMAL YEAR 57.2 33.0 45.1

PRECIPITATION AND WINDS

                   DEPARTURE            DEPARTURE   MAX WIND GUSTS...
MONTH FROM NORM SNOWFALL FROM NORM DIRECTION/MPH/DATE

JANUARY .76 PLUS .25 0.7 MINUS 6.7 NW 52 ON 24TH
FEBRUARY .14 MINUS .37 2.3 MINUS 3.6 NW 37 ON 24TH
MARCH 2.67 PLUS .86 9.3 PLUS 1.2 NW 49 ON 31ST
APRIL 6.17 PLUS 3.52 T MINUS 3.5 NE 52 ON 7TH
MAY 1.02 MINUS 2.37 0 NW 44 ON 12TH
JUNE 3.81 PLUS .32 0 NW 53 ON 20TH
JULY .68 MINUS 2.25 0 S 37 ON 31ST
AUGUST 4.33 PLUS 1.32 0 N 43 ON 24TH
SEPTEMBER 3.88 PLUS 1.30 0 SE 40 ON 15TH,21ST
OCTOBER .33 MINUS 1.60 1.6 PLUS 0.5 NW 48 ON 30TH
NOVEMBER 1.00 MINUS .36 0.8 MINUS 6.8 W 35 ON 1ST
DECEMBER 1.95 PLUS 1.43 1.7 MINUS 5.3 W 43 ON 14TH

2006 26.74 PLUS 2.05 16.4 MINUS 24.2 NW 53 JUN 20TH

RICHARD S. RYRHOLM...CLIMATIC FOCAL POINT

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