SIOUX FALLS AREA
CLIMATIC SUMMARY
2008

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

 

...BIZARRE WEATHER EVENTS WITH TIMELY PRECIPITATION IN SIOUX FALLS IN 2008...

Temperatures averaged out a little below normal for 2008 at 44.5 degrees. This was the first year since 1997 that has averaged below normal. Precipitation was somewhat above normal with 25.47 inches at the Sioux Falls Airport, compared to a yearly average of 24.69 inches. However, a little over 30 inches precipitation occurred in parts of southern Sioux Falls in 2008. To start the year, snowfall was also somewhat above average for the 2007-08 season, with 45.7 inches compared to a normal of 40.6 inches. There were a few bizarre and interesting weather events that hit the area in 2008.

January was a typically cold month with two minor events worth mention. On the 20-21st there was 3.3 inches snowfall at the airport, but more as you went south. On the morning of the 29th, strong northwest winds gusting to 47 mph at 703 AM ushered in much colder air for the day, with wind chills dropping to 30 below zero at noontime, for the coldest daytime wind chills since the previous January. In a just as cold February, there were two more minor snow events…3.2 inches on the 4th and 3.5 inches on the 11th. February 20th brought the most dangerous wind chills of the winter, dropping to 39 below zero at 3 AM, when combining the actual temperature of 17 below zero with a 14 mph wind.

There was a continuous snow cover of a least an inch, and most of this time 3 inches or more, from November 30th 2007 to March 11th 2008 or 103 consecutive days. This was the 8th most consecutive days on record with snow on the ground. The record was 141 days from November 7th 2000 to March 27th 2001. March and April brought more snow and below normal temperatures, with 5 inches in the area on March 16-17th, 3 inches March 26-27th, 6 inches March 31st-April 1st, and 3 inches on April 10th. However, the biggest storm occurred on April 24-25th, with over an inch of rain followed by nearly 4 inches of wet snow. The snowfall was considerably heavier just west and northwest of Sioux Falls with 6 inches at Wall Lake and 9 inches at Madison. This system ranked up there with some of the latest snows, but the latest heavy snow on record for Sioux Falls was 10.5 inches on April 28th 1994.

May 1st brought the first severe weather event of the year. Scattered hail up 1.5 inch in diameter occurred in the area in the early evening, and 4 tornadoes were reported just southeast of Sioux Falls in extreme northwest Iowa.

The first 5 months of 2008 were below normal in temperature, and springtime warming ran late, at least for daily high temperatures. The first 60 degree day was on April 4th and the first 80 degree plus day was May 16th. The average date by when Sioux Falls has already seen 60 degrees is March 14th, and for 80 degrees is April 23rd, so by this gauge, spring ran about 3 weeks late for Sioux Falls.

The summer months of June, July, and August were above normal overall in temperature, and near normal in rainfall. There was sufficient precipitation during the growing season as the area again received timely rains, especially in the third week of July and the second week of August. The first part of June brought a couple of episodes of severe weather and heavy rain. In the first week, between 3 and 4 inches of rain was recorded in Sioux Falls, with 3.02 inches officially at the airport. Urban flash flooding stalled some vehicles on the west side of Sioux Falls in the early morning of June 3rd from 315 to 445 AM, and also in the afternoon of June 5th between 1245 and 430 PM. Moderate to major flooding occurred on the Vermillion River due to heavier rains west of Sioux Falls, and there was extensive lowland flooding damage to farmland and crops.

As far as severe weather, on June 5th two tornadoes were reported west to north of Sioux Falls between 8 and 9 PM CDT. One tornado south of Baltic caused damage to silos, farm buildings, power lines, and numerous trees. On June 12th around 640 PM, dry thunderstorm microbursts caused wind gusts up to 63 mph on the northwest side of Sioux Falls. On June 27th, another tornado destroyed outbuildings 3 miles southwest of Trent in Moody County at 9 PM.

On July 1st, the temperature at Joe Foss Field hit 92 degrees, for the first 90 degree day in 2008. Over the period of record since 1889, the average first date on which Sioux Falls sees 90 degrees or above is May 30th, which is around a month earlier that it occurred this year. Last year in 2007, Sioux Falls first reached 90 degrees on April 29th.

On July 17th, after a 3 week dry spell, thunderstorms brought around a half inch rain to the area around 10 AM CDT. Also hail up to 1 inch in diameter and wind gusts to 70 mph caused some damage just south of Sioux Falls towards Harrisburg. However, a much more widespread heavy rain and severe weather event moved southeast over the area in the mid afternoon of July 19th with 1.50 to 3 inches rainfall in the area. Hail up to one inch, wind gusts to 70 mph, and the heaviest rain hit western to southern Sioux Falls through Lincoln County. On July 30th, one inch hail was reported at 1223 PM CDT southeast of Baltic, and on July 31st, lightning injured two men at a construction site in Sioux Falls at 715 AM.

The most bizarre weather event of 2008 was the heat burst that occurred in the predawn hours of August 3rd. A hot dry downdraft from dissipating thunderstorms produced damaging winds around 60 mph and a rapid rise in temperature from a few miles west of Sioux Falls into the city. Around 430 AM the temperature at the airport rose from the lower 70s to an official 99 degrees, for the warmest temperature of the year.

Another decent rainfall of 1.46 inches occurred at the airport on August 11th. However, it was dry in Sioux Falls for the rest of August. What was interesting was that despite the overall above normal temperature from summer into fall, there were only 6 days with 90 degrees or above in 2008, 5 of them in July, compared to a yearly normal of 22.

September was an uneventful month, but the autumn season of September through November was quite mild overall. The first freezing temperature of 32 degrees of the fall was on October 14th, which made 167 consecutive days above freezing from the 32 degree low on April 29th. This tied for the 7th longest such period on record, and was good for late growing gardens. The first widespread hard freeze did not hit until October 27th, when the low was 23 degrees.

October brought the wettest month of 2008 with a total of 5.44 inches at the airport, for the 5th wettest October on record. Monthly precipitation was closer to 7 inches in western Sioux Falls where over 3 inches rain was measured on the 6th. The other big rain event of the month was on October 22-23rd when 2 to 2.5 inches occurred over the city. The strongest wind of the year at the airport was recorded at 833 PM CDT on October 25th, with a wind gust from the northwest at 63 mph.

November started the snow season, and December brought the winter cold for the first below normal temperature month since May. There were numerous 1 to 3 inch snow events in November and especially December, with the heavier snowfalls skirting to the north and south of Sioux Falls. December added up to 12.5 inches at the airport, compared to a normal of 7.0 inches, for a seasonal total at the end of the year of 15 to 20 inches in the Sioux Falls area.

THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 2008 AT THE SIOUX FALLS AIRPORT...

TEMPERATURES

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

JANUARY 23.5 3.9 13.7 MINUS 0.3 43 19B
FEBRUARY 24.9 4.8 14.8 MINUS 6.0 42 19B
MARCH 38.0 20.4 29.2 MINUS 3.4 53 11B
APRIL 55.4 31.2 43.3 MINUS 2.4 78 19
MAY 67.5 45.2 56.4 MINUS 1.4 82 33
JUNE 80.0 56.3 68.2 PLUS 0.7 88 48
JULY 85.7 63.4 74.5 PLUS 1.5 96 50
AUGUST 83.0 60.1 71.5 PLUS 0.7 99 48
SEPTEMBER 75.6 50.2 62.9 PLUS 2.0 89 37
OCTOBER 60.8 38.1 49.5 PLUS 1.5 76 22 5TH WETTEST
NOVEMBER 43.4 25.7 34.6 PLUS 3.3 76 5
DECEMBER 25.5 5.0 15.3 MINUS 3.0 49 13B

2008 55.3 33.7 44.5 MINUS 0.6 99 19B
NORMAL YEAR 57.2 33.0 45.1

PRECIPITATION (INCHES) AND WINDS

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

JANUARY .23 MINUS .28 4.1 MINUS 3.3 NW 49 ON 28TH
FEBRUARY .57 PLUS .06 7.5 PLUS 1.6 N 47 ON 17TH
MARCH 1.34 MINUS .47 14.5 PLUS 6.4 NW 44 ON 25TH
APRIL 2.68 PLUS .03 7.6 PLUS 4.1 S 51 ON 15TH
MAY 3.34 MINUS .05 0 E 60 ON 23RD
JUNE 3.95 PLUS .46 0 S 54 12TH,NW 54 28TH
JULY 2.52 MINUS .41 0 NW 44 11TH,N 44 17TH
AUGUST 1.91 MINUS 1.10 0 SW 41 3RD,W 41 11TH
SEPTEMBER 1.78 MINUS .80 0 S 39 ON 1ST
OCTOBER 5.44 PLUS 3.51 trace MINUS 1.1 NW 63 ON 25TH
NOVEMBER 1.01 MINUS .35 3.4 MINUS 4.2 NW 45 ON 7TH
DECEMBER .70 PLUS .18 12.5 PLUS 5.5 NW 48 ON 14TH

2008 25.47 PLUS .78 49.6 PLUS 9.0 NW 63 OCT 25TH

RICHARD S. RYRHOLM...CLIMATIC FOCAL POINT

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