SUBJECT: Rainfall totals from July 9-11.
FROM: Bob Weisman
Earth Sciences, St. Cloud State University
Additional rain fell during Wednesday evening, pushing all of the rainfall totals higher. Another .21 inch was recorded at Saint Cloud State University. This additional rain brought the total July 10 rainfall at the Earth and Atmospheric Sciences Department to 4.29 inches. This still falls short of the 4.40 inches recorded on August 25-26, 1995. Still, July 10 ranks as the second heaviest 24-hour rainfall event in the 12-year history of Saint Cloud State University rainfall records.
Again, the bulk of the rain fell between 7:00 AM and 8:45 AM when 2.70 inches were recorded. This is also the period when most of the damage occurred. To put this in perspective, the normal amount of rainfall for the entire month of July is 3.38 inches. Also, that 1 hour and 45 minute rainfall by itself would have ranked 4th by itself on the list of heaviest SCSU rainfalls. This rain was whipped by southeast winds that gusted as high as 52 MPH as recorded by SCSU. The total storm rainfall from Wednesday evening through last night was 4.44 inches.
Additional rainfall at the Saint Cloud Airport during the evening raised the daily rainfall for July 10 to a record 1.95 inches, breaking the old daily record of 1.76 inches, set in 1933. The total storm rainfall at the Saint Cloud Airport was 2.04 inches from this storm.
In official Saint Cloud records, there have been 4 times in which the daily rainfall exceeded 4 inches. All four events took place in July and August (see table below). The most rainfall in a 24-hour period was 4.80 inches on July 2, 1903. The most recent heavy rain event happened on April 22, 2001 when 3.52 inches fell. That storm was part of the record April rainfall when 8.42 inches fell, breaking the old record by more than 2 inches. These events do not include the SCSU rain gauge, since SCSU is not the official Saint Cloud weather observation site.
As of yesterday afternoon, the heavy rainfall was forecast to push the Sauk River above flood stage in Saint Cloud this weekend. The river is forecast to rise out of its banks by midday Saturday, cresting at a foot above flood stage on Sunday evening. The river is forecast to stay at that high level through Monday. The Mississippi River in Saint Cloud is also expected to rise above flood stage at the official gauge, located below the dam, as well. The river is forecast to overflow its banks on Saturday afternoon and rise half a foot out of its banks on Monday. This means that there will be some minor flooding on 5th Ave North near Cathedral High School, south of Sportsmans Island Road, and in Musinger Gardens and Wilson Park. In addition, the fishing pier along the Beaver Island Trail will be under water (as of 6 AM this morning, waves will already lapping onto the pier). These forecasts assume no more rain will fall in the basin, which should be a good assumption through at least Saturday.
The high rainfall at SCSU also illustrates the potential problem with the automated rainfall-measuring instrument used at the Saint Cloud Municipal Airport. Between 7 and 9 AM, the Saint Cloud Airport reported only .32 inch of rain. While rainfall in thunderstorms can vary widely, it is extremely unlikely, judging by radar coverage this morning, that the Airport received this little amount of rainfall. Some meteorologists, including myself, believe that the equipment used at the Airport cannot keep up during periods of extremely heavy rainfall. This problem appeared during the heavy rain event of June 24. While the SCSU gauge received 1.65 inch in an hour, the airport reported only 1.10 inch. Also, during the record SCSU rainfall of 4.40 inch on August 25-26, 1995, the Saint Cloud Airport received only 2.77 inches of rain. This topic will be a subject of future research.
Two-day rainfall totals in Central Minnesota as of 7 AM include: July 9-11 rainfall Rainfall since last Sunday (July 7 7 AM) Glenwood 4.53 inches+ SCSU 4.40 inches 4.93 inches Long Prairie 4.07 inches+ 7.26 inches Alexandria Airport 3.53 inches 3.84 inches Fergus Falls 2.90 inches 4.48 inches Brainerd 2.49 inches 8.01 inches Saint Cloud Airport 2.04 inches 2.64 inches Melrose 2.00 inches& Mora 1.76 inches 3.78 inches Alexandria Cooperative Observer* 1.69 inches 3.89 inches Royalton 1.46 inches& Wadena 1.42 inches 2.96 inches Park Rapids 1.00 inch 2.70 inches Detroit Lakes 0.54 inches 2.31 inches *Located 6 miles N of Alexandria; uses manual rain gauge &Totals only available between 7 AM Wednesday and 7 AM Thursday + Totals only available between 7 AM Tuesday and 7 AM Wednesday HEAVIEST DAILY RAINFALL TOTALS IN SAINT CLOUD HISTORY (AIRPORT) AMOUNT (in) DATE 4.80 2 July 1903 4.57 3 August 1956 4.50 6 July 1897 4.12 19 August 1935 3.90 24 August 1895 3.62 8 September 1985 3.59 27 August 1960 3.52 22 April 2001 1.96 10 July 2002 (record rainfall for July 10; old record 1.83 in 1933) HEAVIEST DAILY RAINFALL TOTALS IN SCSU HISTORY (1991-2002) AMOUNT (in) DATE 4.40 25-26 August 1995 4.29 10 July 2002 3.83 23 April 2001 2.57 2 August 1997 2.37 7 September 1991 2.35 19 August 1997 2.25 25 July 1997 2.16 16 June 1994 2.07 26 August 1993
Last modified: July 12, 2002