SIOUX FALLS AREA
CLIMATIC SUMMARY
2005

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

...RATHER WARM AND WET YEAR IN THE SIOUX FALLS AREA IN 2005...

Overall both temperature and precipitation were well above normal in the Sioux Falls area in 2005. There were two major winter storms in the area, one in March and the other in late November. Warm-season thunderstorms produced the typical severe weather and heavy rains, but the worst of the flash flooding occurred outside of Sioux Falls in 2005. Precipitation totaled 31.71 inches at the Sioux Falls airport, or 7.02 inches above normal for the year. The temperatures averaged 47.9 degrees for 2005, or 2.8 degrees above the normal of 45.1 degrees.

The year of 2005 started on a wetter, snowier, and colder note than 2004 ended. A thunderstorm was observed on January 1st, but with only .03 inch precipitation. However, from January 4-5th, 8.0 inches snowfall was measured, with 6.4 inches of this occurring within a 24-hour period. The low temperature for 2005 of 19 degrees below zero was then recorded on January 15th. Temperatures rebounded nicely the rest of the month, melting off the snow cover by January 25th. Record high temperatures occurred on February 3rd and 4th, with highs of 58 and 61 degrees respectively.

Overall it remained rather mild with little snow cover, until a major snowstorm dumped 12.2 inches from the evening of March 17th through the afternoon of March 18th. It was the 5th heaviest 24-hour snowfall on record for the month of March, and the 11th heaviest 24-hour snowfall of any month since records began in Sioux Falls in 1893. Before this winter storm, there was a wind event on March 10th that should be mentioned, as strong northwest winds gusted up to 60 mph at the airport, for the strongest recorded wind gust of 2005. The snow cover all melted off again by March 27th, commencing an early spring warmth with well above normal temperatures through the first three weeks of April, before cooling off again.

The thunderstorm season also started early on April 10th with hail up to an inch in diameter reported in Sioux Falls at 450 AM. Severe thunderstorm wind gusts of 60 to 80 mph caused various damage in an area from southwest to northwest of Sioux Falls from Bon Homme to McCook to Lake counties from 530 to 730 AM. More hail occurred in the Sioux Falls area in the late morning of April 16th and the late afternoon of April 17th. Rainfall and severe weather were quite plentiful during the growing season from April through July with a total of 16.86 inches precipitation at the airport, or 4.40 inches above normal. Various severe thunderstorms with large hail and/or damaging wind occurred in parts of the area on the following dates...May 5-8th, 10-12th, and 24th; June 3-4th, 7-9th, and 20th; July 7th, 11th, 20th, 24-25th, and 29th; August 3rd; and September 5th, 8th, 12th, and 18th. The heaviest precipitation event of 2005 occurred in the evening of September 24th with 1.16 inches in one hour between 7 and 8 pm, with 2.01 inches within a 24-hour period. The heavy rains resulted in minor street and basement flooding in Sioux Falls, but nothing like the two destructive flash floods in the late spring of 2004.

The summer of 2005 from June to September and even into early October was warm and humid overall, averaging above normal in temperature. The peak of the summer discomfort occurred on July 23rd with the high temperature for 2005 of 99 degrees registered at the airport. At 3 PM that afternoon, the temperature of 98 degrees combined with a sultry dewpoint of 75 degrees produced a heat index of 111 degrees, for one of the higher heat indices ever recorded. The above normal temperatures continued from September through much of November. Two record daily high temperatures occurred in November, one on the 2nd with a high of 77 degrees breaking the old record by 5 degrees, and the other on the 11th with a record high of 70 degrees.

This just lulled us into complacency until a major winter storm hit the area near the end of November, signaling a significant change in the weather pattern. On November 28th an overnight heavy rain changed to snow and blowing snow during the day, totaling around 2 inches precipitation and 6 inches snowfall. Of course the bigger problem was west of Sioux Falls towards the James Valley where the rain was freezing on contact, causing a very damaging ice storm before the blizzard. Then another heavy snow hit just two days later on November 30th with around 7 inches snowfall in Sioux Falls. The new heavy snow cover helped set the stage for a record early season cold spell through the first 8 days of December. During this period, daily high temperatures were all 15 degrees or less and the daily lows were well below zero, reaching -13 on the 2nd and 6th. Temperatures again recovered nicely for the rest of December, but the rather unsettled weather pattern continued with above normal precipitation for the month. 

THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 2005 AT THE SIOUX FALLS AIRPORT...

TEMPERATURES


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

JANUARY        24.4   7.6     16.0    PLUS 2.0   53  19B
FEBRUARY       39.0  18.1     28.6    PLUS 7.8   61   3B
MARCH          45.0  21.8     33.4    PLUS 0.8   74   6
APRIL          64.0  40.2     52.1    PLUS 6.4   81  24  
MAY            67.3  45.3     56.3   MINUS 1.5   81  20             
JUNE           80.7  60.1     70.4    PLUS 2.9   93  48
JULY           85.9  64.1     75.0    PLUS 2.0   99  47
AUGUST         80.9  59.3     70.1   MINUS 0.7   91  46             
SEPTEMBER      79.8  55.0     67.4    PLUS 6.5   93  34   6TH WARMEST
OCTOBER        62.7  38.2     50.5    PLUS 2.5   86  21
NOVEMBER       48.2  25.4     36.8    PLUS 5.5   77   5   5TH WETTEST
DECEMBER       25.3  10.5     17.9   MINUS 0.4   45  13B
 
 2005          58.6  37.1     47.9    PLUS 2.8   99  19B
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     .44   MINUS  .07      9.5     PLUS 2.1      NW 54 ON 21ST
FEBRUARY   1.12    PLUS  .61      4.0    MINUS 1.9       S 40 ON 5TH
MARCH      1.53   MINUS  .28     13.4     PLUS 5.3      NW 60 ON 10TH
APRIL      3.33    PLUS  .68       T     MINUS 3.5      NW 43 ON 25TH 
MAY        5.22    PLUS 1.83       0                    SE 45 ON 21ST
JUNE       3.72    PLUS  .23       0                     S 45 ON 21ST
JULY       4.59    PLUS 1.66       0                    NW 58 ON 20TH
AUGUST     1.36   MINUS 1.65       0                    NW 43 ON 3RD
SEPTEMBER  4.76    PLUS 2.18       0                     S 37 ON 17TH
OCTOBER    1.66   MINUS  .27       T     MINUS 1.1      NW 39 ON 6TH 
NOVEMBER   2.95    PLUS 1.59     14.3     PLUS 6.7       N 54 ON 28TH
DECEMBER   1.03    PLUS  .51      8.5     PLUS 1.5       W 39 ON 14TH

 2005     31.71    PLUS 7.02     49.7     PLUS 9.1     NW 60 MAR 10TH

RICHARD S. RYRHOLM...CLIMATIC FOCAL POINT


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