Preliminary Climate Summary for August 2020:
Warm and wet are to two words to describe the climate of August 2020 in Minnesota. Most areas of the state show average temperatures for August of 2020 that are 1-3°F above normal. Extremes for the month ranged from 97°F at Marshall (Lyon County) on the 24th to just 36°F at Seagull Lake (Cook County) on the 4th. There were several days that the NOAA National Weather Service issued Heat Advisories or Excessive Heat Warnings thanks to unusually high dew points. At MSP the number of hours with dew point readings of 70°F or higher exceeded 100 for the month. The total of such hours is now well over 325 for the summer so far.
August wraps up meteorological summer and is the third consecutive warmer than normal month. The June-August period in 2020 will rank among the 5 warmest historically for the state of Minnesota.
August rainfall was above normal at most locations. Portions of Cass, Clearwater, Stearns, and Itasca Counties reported over 8 inches of rain for the month. Over 80 climate stations reported 5 or more inches of total rainfall. Within the Minnesota Cooperative Climate Station Network at least 42 daily rainfall records were tied or set during August. Artichoke Lake (Big Stone County) and Wright (Carlton County) reported three new daily rainfall records during the month. It is very unusual for a climate station to record 3 record-setting rainfalls in one month. Another oddity was the both Ottertail and Long Prairie reported back to back record setting rainfalls (over 2 inches) on August 13-14.
With a wetter than normal August the meteorological summer (June-August) in Minnesota will end up among the 20 wettest historically back to 1895, with a statewide average rainfall over 13 inches.
One of the drier areas was southeastern Minnesota where Caledonia (Houston County) has reported just 0.37 inches which will be their driest August in history if they get no more rain before the end of the month.
Weekly Weather Potpourri:
The NOAA-National Hurricane Center reported that Hurricane Laura came ashore near Cameron, LA early in the morning on August 27 with winds up to 150 mph (Category 4). It also brought widespread 6-10 inches rainfall amounts and significant storm surge. Damage surveys were still being conducted in both LA and TX on Thursday and Friday this week. Over half a million people were without power. The Weather Underground web site reported extensively on this storm.
Also, earlier in the week Typhoon Bavi struck portions of South Korea and North Korea bring 12-16 inches of rainfall and a good deal of flash flooding. It is somewhat rare for a typhoon to strike that far north. The BBC News reported more detail.
Researchers from the University of Arizona have reported from paleo-climate studies that the global average temperature during the Last Glacial Maximum, 20,000 years ago was about 46°F. This compares to a value of 57°F for the 20th Century global average. The Arctic Region during the Last Glacial Maximum was about 25 degrees F colder than it is today. You can read more from this study at Science Daily.
MPR listener question:
We heard you speak last week about 1969 as a very dry August in southeastern Minnesota. It seems like recently August has been consistently wetter than normal. When was the last super dry August in Minnesota?Answer:
The last super dry August on a statewide basis was in 2003 when the average rainfall over the state was 1.41 inches. Historically this was 2nd driest behind 1.11 inches in 1930. I might add that in the 17 years since 2003 twelve years have brought a near normal or wetter than normal August to Minnesota.Twin Cities Almanac for August 28th:
The average MSP high temperature for this date is 78 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 60 degrees F (plus or minus 7 degrees F standard deviation).MSP Local Records for August 28th::
MSP records for this date include: highest daily maximum temperature of 94 degrees F in 1955; lowest daily maximum temperature of 61 degrees F in 1935; lowest daily minimum temperature of 42 degrees F in 1934; highest daily minimum temperature of 75 degrees F in 1969; record precipitation of 1.11 inches in 1950. No snowfall has been reported on this date.
Average dew point for August 28th is 59°F; the maximum dew point on this date is 77°F in 1955; and the minimum dew point on this date is 34°F in 1946.
All-time state records for August 28th:
The state record high temperature for this date is 104 degrees F at Canby (Yellow Medicine County) in 1937. The state record low temperature for this date is 21 degrees F at Tower (St Louis County) in 1986. The state record precipitation for this date is 6.00 inches at Litchfield (Meeker County) in 1960. No snowfall has been reported on this date.
Past Weather Features:
August 28, 1984 was the hottest in history with most parts of the state reporting afternoon temperatures in the 90s F. In the west, portions of Lyon, Marshall, Clay, Norman, and Traverse Counties saw the thermometer top 100°F.
Portions of ten northern Minnesota counties reported frost on the morning of August 28, 1986. Tower, Thorhult, Hibbing, and Cotton reported morning lows in the 20s F.
August 28-29, 2002 brought heavy thunderstorms to northwestern Minnesota and the Red River Valley. Many climate stations reported 2-5 inches of rain with hail. Red Lake Falls and Argyle reported nearly 6 inches of rainfall. It was the last heavy rains of a very wet summer in northwestern Minnesota.
Outlook:
Sunny and cooler over the weekend, with lower humidity and pleasant temperatures. Increasing cloudiness on Sunday night with a chance for showers and thunderstorms late. Continued chance for showers and thunderstorms on Monday and Tuesday, then pleasant for the balance of next week.
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