SIOUX FALLS AREA
CLIMATIC SUMMARY
1998

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

 

...ROLLER COASTER RIDE IN THE WEATHER AROUND SIOUX FALLS IN 1998...

1998 featured a wild weather roller coaster ride in the Sioux Falls tri/state area. There were a number of severe and offseason weather events and both precipitation and temperature patterns featured wide swings. Overall, 1998 was relatively warm and wet with the temperature averaging 47.5 degrees or 2.0 degrees above normal...and precipitation totaling 31.12 inches at the airport or 7.26 inches above normal. The following is a chronological summary for 1998 for the Sioux Falls area.

The year started warm with the winter period of December, January, and February as the 6th warmest such period since records started in 1893. There was a record high of 55 degrees on January 1st followed by a brief cold spell in which the low temperature for the year of 20 below zero occurred on January 13th. February averaged 12.1 degrees above normal which tied the 4th warmest February on record. There was even a 3/4 inch hail report in Sioux Falls on February 25th.

March was the wettest march on record with a total of 4.08 inches of melted precipitation. 1.54 inches rainfall occurred at the airport on March 27th...a record for the date. On March 29th unseasonably early severe thunderstorms developed just southeast of Sioux Falls and moved into southwest Minnesota producing a number of significant tornadoes...two of which devastated comfrey and St. Peter Minnesota. Just 2 days later on the 31st Sioux Falls experienced a heavy wet snowfall of 9.3 inches with a water equivalent of 1.32 inches. The total march snowfall of 21.4 inches was the 5th snowiest march on record.

In April on the 12th strong south winds sustained at 40 mph for several hours and gusting to 55 mph caused some tree and power line damage in the area and blew out a few windows in Sioux Falls. On May 28th one inch diameter hail occurred in far southern Sioux Falls between 530 and 6 pm. Two days later at 838 pm an f4 rated tornado destroyed Spencer SD which is 45 miles west/northwest of Sioux Falls. This large and powerful tornado killed 6 and injured 150 people in Spencer. Fortunately the tornado weakened and dissipated as it moved towards Sioux Falls...but it did show that this area can experience very strong tornadoes.

The 1st week of June featured a return to unseasonably cold weather in fact sleet was reported at the airport early on the 3rd with snowflakes also reported in the Sioux Falls area. June was not only cool but also wet. On the 11th one inch diameter hail occurred at Hartford and on the 24th severe thunderstorms struck the area with winds gusting to 56 mph at Sioux Falls airport. However the most severe thunderstorm of the summer and the year occurred on the evening of July 18th interrupting the Jazz Fest with the strongest winds of the year of 64 mph...downpours up to 1 1/3 inches rainfall...and continuous cloud to ground lightning. Severe thunderstorms were also in the area on the morning of august 24th when winds gusted to 54 mph at the airport.

Generally however the last 3 weeks of august through September were dry and temperatures were consistently above normal. The warmest temperature of the year of 92 degrees was recorded on both September 6th and the 12th. October dramatically turned around the dry spell. A major low pressure system brought 2.36 inches rainfall on the 4th...a record for the date and the heaviest rainfall event of the year. October ended up with 6.28 inches precipitation...just second to the wettest October on record of 6.89 inches in 1911.

The only weather event of November was a whopper...a wet blizzard on the 10th...announced by loud thunder and lightning, and a monthly record low barometric pressure of 28.91 inches before sunrise. This snowstorm dumped 12.6 inches on the 10th along with a water equivalent of 1.38 inches...both records for the date. The snowfall also officially was the 9th heaviest 24 hour snowfall on record and made November 1998 the 5th snowiest November on record.

This snowstorm just temporarily put a damper on the mild fall with the last half of November through the first half of December featuring an outstanding warm dry spell. Every day from November 21st through December 18th was well above normal with the 28 day period averaging 15.0 degrees above normal. The warmest temperature in November of 63 degrees occurred on the 27th. This was not a record for the date but the high of 63 on December 1st...2nd...and 3rd were not only records for their respective dates but also broke the all time record for the whole month of December. The previous record high for December was 62 degrees on the 3rd in 1941. A record high of 57 degrees also was registered on the 14th. The warm spell came to an abrupt end on December 19th and most of the rest of the month was well below normal in temperatures.

THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 1998 AT THE SIOUX FALLS AIRPORT...

TEMPERATURES

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

JANUARY 27.6 11.5 19.6 PLUS 5.8 55 20B 55 ON 1ST
FEBRUARY 39.5 24.1 31.8 PLUS 12.1 58 3 TIE 4TH
WARMEST
MARCH 34.8 21.2 28.0 MINUS 4.5 77 12B 5TH SNOWIEST
APRIL 58.3 34.7 46.5 MINUS 0.4 78 23
MAY 74.1 49.3 61.7 PLUS 3.3 88 38
JUNE 74.1 52.1 63.1 MINUS 5.2 89 37
JULY 82.5 61.3 71.9 MINUS 2.4 91 50
AUGUST 80.6 61.4 71.0 MINUS 0.4 91 51
SEPTEMBER 80.1 52.4 66.3 PLUS 5.4 92 34
OCTOBER 61.1 40.1 50.6 PLUS 2.0 73 27 2ND WETTEST
NOVEMBER 44.0 26.9 35.5 PLUS 2.5 63 8 5TH SNOWIEST
DECEMBER 35.6 12.4 24.0 PLUS 5.7 63 11B 63 ON 1/2/3

1998 57.7 37.3 47.5 PLUS 2.0 92 20B

NORMAL YEAR 56.8 34.2 45.5

PRECIPITATION (INCHES) AND WINDS

PRECIPITATION      DEPARTURE             DEPARTURE     MAX WIND GUSTS
(INCHES) MONTH FROM NORM SNOWFALL FROM NORM DIRECTION/MPH/DATE

JANUARY .50 MINUS .01 11.7 PLUS 5.0 NW 36 ON 9TH
FEBRUARY .67 PLUS .03 6.9 MINUS 0.8 SE 44 ON 25TH
MARCH 4.08 PLUS 2.44 21.4 PLUS 13.4 NE 39 ON 31ST
APRIL 3.57 PLUS 1.05 0.3 MINUS 1.9 S 55 ON 12TH
MAY 1.92 MINUS 1.11 0 W 53 ON 30TH
JUNE 4.52 PLUS 1.12 T W 56 ON 24TH
JULY 2.66 MINUS .02 0 NW 64 ON 18TH
AUGUST 3.29 PLUS .44 0 NE 54 ON 24TH
SEPTEMBER 1.19 MINUS 1.83 0 NW 37 ON 26TH
OCTOBER 6.28 PLUS 4.50 0 MINUS 0.6 40 MPH 4,11,16
NOVEMBER 2.20 PLUS 1.11 14.8 PLUS 9.7 NW 54 ON 10TH
DECEMBER .24 MINUS .46 9.0 PLUS 1.2 N 39 ON 18TH

1998 31.12 PLUS 7.26 64.1 PLUS 26.0 NW 64 JUL 18TH

RICHARD S. RYRHOLM/ CLIMATIC FOCAL POINT

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