September 2000 Saint Cloud Weather Summary

DATE: 2 October 2000

SUBJECT: Driest September Since 1952 Further Fuels Drought
         Saint Cloud September 2000 weather summary

The localized drought in east central Minnesota continued through September in St. Cloud. The Saint Cloud Municipal Airport only received 0.93 inches of rainfall during September, more than 2.2 inches below normal. This low rainfall tied 1923 for the 9th driest September on record and was the driest September since 1952, the driest September in 108 years of St. Cloud weather records (see table below). There were no really large rainfall events during the past month. The rainiest day was on the 9th when St. Cloud received .35 inch from thunderstorms.

The St. Cloud area missed a potential major rainfall event on the 22nd and 23rd. A storm system set up an inverted trough, a focus of ongoing research by the National Weather Service Sioux Falls Office and SCSU. This feature distorted the normal frontal rainfall distribution, so only the northwestern and the southeastern parts of Minnesota received significant rain. Instead, the parched region from St. Cloud to the northern Twin Cities suburbs got less than 0.2 inch.

The dry September left St. Cloud with a 2000 growing season (Apr 1- Sep 30) of 12.46 inches, nearly 8 inches below normal. This is the 6th lowest growing season rainfall in St. Cloud in the 109 years of records (see table below). Combined with the rainfall deficit from last fall (2.1 inches), St. Cloud is now more than 10 inches of rainfall behind during the growing season since September of last year. Also, note that 3 of the last 10 years (1992, 1996, 2000) rank in the 7 driest growing seasons to date.

The average temperature during September 2000 in St. Cloud was 57.6 degrees, which was very close to normal. This means that the cold outbreak of September 20-27 (highs of 61 or colder on 6 days; lows in the 20's on 3 mornings) was balanced by 8 days with highs in the 80's including 3 days in a row twice (Sept 16-18 and Sept 28-30). Note, however, that the average high (71.9 deg) was 2.8 degrees above normal while the average low (43.2 deg) was 2.2 degrees below normal. This range of temperatures can be attributed to the dry conditions: less water vapor in the air means more of the sun's heat gets through during the day and more of the earth's warmth escapes at night. The "jaw dropper" of temperature range occurred on the 16th with an afternoon high of 85 after a morning low of 35. Four other days had a high at least 40 degrees warmer than the low.

The growing season came to an abrupt halt in St. Cloud with a 28 degree low on the morning of September 21. Whatever survived stopped 3 days later thanks to a record cold low of 24 on the 24th. While the first frost was close to the normal date of September 26, the late start to the growing season with the last frost coming with a record low of 28 on May 19, led to a frost-free season which was more than 2 weeks shorter than normal and a freeze-free season which was more than a month shorter than normal (see table below). The late freeze was also indicative of the rather cool conditions which dominated large portions of May and June.

SUMMARY FOR SEPTEMBER 2000             SEP 2000         NORMAL
TEMPERATURE
Average high temperature ( F)           71.9             69.1
Average low temperature ( F)            43.2             45.4
Average temperature ( F)                57.6             57.3
Warmest high for this month ( F)        89 on the 9th
Coolest high for this month ( F)        50 on the 23rd
Mildest low for this month ( F)         61 on the 9th
Coldest low for this month ( F)         24 on the 24th (broke record;
                                                        see below)
Records broken:
Daily high temperature:                 88 (tie) on the 18th (1984 and 1998)
Daily low temperature:                  24 on the 24th (old record: 25 in 1942)

PRECIPITATION (in)
September                                .93*             3.14
Greatest in 24 hours (Sept 2000)         .35 on the 9th
Growing season rainfall (Apr 1-Sep 30) 12.46**           20.32
*-(tie) 9th driest Sept on record (see below)
**-6th driest growing season thru Sep 30 (see below)

GROWING SEASON STATISTICS
Temperature cutoff        last day in spring   first day in fall  no of days
32 degrees                   
2000                          May 19              Sept 21             125
normal                        May 10              Sept 26             142

28 degrees
2000                          May 19              Sept 21             125
normal                        April 28            Oct  8              161

     ST. CLOUD PRECIP--SEPTEMBER (108 YEARS; AVG =  2.95 IN; SDEV =  1.88 IN)

         WETTEST                           DRIEST

     10.72 IN  1926                      0.07 IN  1952
      9.48 IN  1985                      0.68 IN  1943
      7.12 IN  1900                      0.74 IN  1922
      6.60 IN  1929                      0.78 IN  1932
      6.55 IN  1983                      0.80 IN  1919
      6.49 IN  1914                      0.81 IN  1893
      6.28 IN  1986                      0.84 IN  1918
      6.12 IN  1934                      0.90 IN  1935
      6.10 IN  1921                      0.93 IN  1923
      5.99 IN  1980                      0.93 IN  2000 <-- TIED 9TH DRIEST;
                                                           DRIEST IN 48 YRS

===========================================================================
 GROWING SEASON PRECIP: APR 1-SEP 30
 AVG = 19.95 SDEV = 4.99; 111 YRS; 108 GOOD YRS

 10 DRIEST GROWING SEASONS - APR 1-SEP 30
  10.52 1922
  10.58 1976
  11.29 1931
  11.57 1996
  12.33 1910
  12.46 2000 <--6TH DRIEST; 3RD YR IN 1991-2000
  12.47 1992
  13.82 1930
  14.16 1950
  14.17 1933

 10 WETTEST GROWING SEASONS - APR 1-SEP 30
  26.71 1906
  26.73 1912
  27.17 1990
  27.44 1928
  27.98 1926
  28.77 1985
  28.83 1903
  29.76 1897
  30.70 1905
  30.90 1965
  31.17 1986