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This Month's Daily Statistics
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SUBJECT: Heaviest Daily Rainfall in 14 Years Finishes Near Normal Summer
St. Cloud August 1999 and summer 1999 weather summaries
August 1999 in St. Cloud was marked by cooler temperatures than July
and heavier rainfall. According to the statistics from the St. Cloud
Municipal airport, nearly 5 inches of rain fell, which was more than an
inch above normal. More than three-quarters of the rain (3.77 inches) fell from
the 18th on, including an incredible 2.81 inches on the evening of the 21st.
The rainfall of August 21 set a record for the most rainfall on that date
and was the highest daily rainfall total in St. Cloud since September 8, 1985
when 3.62 inches fell. The 21st rainfall was the highest August daily rainfall
since August 7, 1980 when 3.43 inches fell.
The most remarkable elements of this large rain total was: 1) It was from
a relatively weak weather system which intensified right over the Mississippi
River from Little Falls to Elk River, so only St. Cloud and Hutchinson
picked up over 2 inches of rain while most other Minnesota stations were
under an inch and 2) the rain fell in only 3 hours.
The heavy rainfall pushed St. Cloud summer precipitation to nearly
an inch and a half above normal.
St. Cloud temperatures were near normal for August and slightly above
normal for the meteorological summer season (June 1-August 31). This marks
only the third year in this decade which has had an above normal summer
average temperature.
To many, this summer seemed mighty uncomfortable, but only July had
temperatures significantly above normal. The number of 90-degree days
was a bit above normal and we did hit 97 and 98 degrees on a couple of
days, but heat waves have been much worse in the past.
This led me to wonder if the problem was the persistent high humidity.
There aren't any long-term sources of heat index since it is a relatively
new statistic; however, I estimated humidity by noting the low temperatures,
since the low temperature usually remains at or above the dew point for the
day. Note that August's lows averaged more than a degree and a half above
normal and the summer low temperatures were more than 2 degrees above normal.
Since a 60 degree dew point usually marks the boundary when we begin
to feel uncomfortable, I looked through the St. Cloud historical records
to see if we had a high number of days this summer with a low temperature of
60 or warmer. We did have 37 days with a low in the 60's or 70's, but that
is not much above the 1896-1998 average number of days, which is 35.1. We had
14 days with a low of 65 or higher (average is 13.4) and 3 days with
a low in the 70's (average 3.2). Again, this leads me to conclude that
our relatively cool summers of the 1990's make a near normal summer more
difficult to tolerate.
AUGUST STATISTICS AUG 1999 NORMAL TEMPERATURE ( F) Average high temp 78.2 79.4 Average low temp 56.4 54.8 Average temp 67.3 67.1 Warmest high for the month 91 on the 27th Coolest high for the month 65 on the 30th Warmest low for the month 65 on the 15th Coolest low for the month 46 on the 14th Records: none PRECIPITATION (IN) Total for month 4.97 3.96 Maximum daily amount 2.81 on the 21st (record; see below) Records: Daily rainfall: 2.81 on the 21st (old record: 2.54 in 1936) SUMMER STATISTICS SUMMER 1999 NORMAL Avg high temperature (F) 79.9 79.8 Avg low temperature (F) 57.2 54.9 Average temperature (F) 68.6 68.2 Total Precipitation (in) 12.83 11.44 Number of highs >= 90 deg 12 10.7
