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Let's Declare May as "Hail Month"

Let's Declare May as "Hail Month":

After writing so much about severe thunderstorms that brought hail and wind damage to Minnesota last week, this Thursday, May 19 produced the most single day hail reports so far. There were 98 reports of large hail (1” diameter or greater) spread over ten counties, mostly in east-central and southeastern Minnesota. Some hail near Albert Lea ranged up to 3 inches in diameter. Many areas of the Twin Cities reported marble to ping pong sized hail stones, that shredded tree leaves and temporarily blocked up storm drains.

These reports of large hail added to the monthly total. According to the NOAA-Storm Prediction Center Minnesota has filed over 280 reports of large hail (1 inch diameter or bigger) over six dates this month. That is a large number even for an annual total of reports.

Some of the storms bringing large hail on Thursday, May 19th also brought heavy rainfalls, ranging from 0.5 inches to 1.5 inches, especially in southeastern counties. Reports of 3 and 4 inches of rainfall around the Winona, Stockton, Minnesota City area caused the National Weather Service to issue a Flash Flood warning on Thursday evening. This included portions of Whitewater State Park.

This rainfall added to already abundant monthly totals in many areas of the state. Climate observers in 13 Minnesota counties already report over 6 inches of rainfall so far this month. Many of the rivers and streams are running at or above flood stage. In fact, a recent web site post by the Minnesota State Climatology Office documents the year-to-date-precipitation totals across northern Minnesota and the historic flood crests being measured on the Rainy River Basin, and Pigeon River Basin.

Wet soils in many areas of the state are preventing farmers from catching up on an already late planting season. For major crops (corn and soybeans) this may be the latest plating season since 1979. It looks like farmers will have to continue to work between showers over the next week or two but should have a few more field working days than in recent weeks. At least they won’t have to expect snow like some North Dakota farmers this week.

Weekly Weather Potpourri:

NOAA this week features a global climate summary for April of 2022 which ranked 5th warmest historically. It was significantly colder than normal throughout Minnesota. The NOAA report also highlights the precipitation patterns of April, showing the surplus values throughout the Great Lakes Region.

This week a subtropical cyclone named Yakecan battered portions of Uruguay and Brazil with strong winds, heavy rains, and hail. The BBC reported that two deaths were blamed on the storm and at least 220,000 residents in southern Brazil were left without power for a time. Yakecan was one of the strongest such storms to impact these countries in many years.

Recent research published in Earth and Space Science documents expected shifts in snowmelt runoff across the Colorado River Basin due to climate change. Peak runoff periods will occur earlier in the year and will have implications for reservoir management, as well as irrigation management in some western states.

MPR listener question:

With the 92°F maximum temperature in the Twin Cities last Thursday (May 12th), we finally had our first afternoon beer sitting out on the deck. One of the neighbors who is new to Minnesota asked me if there is always at least one 90°F temperature reading in May? I said I knew just the right person to ask. So how about it?


Sure. The Twin Cities climate records go back to 1873, a period of 150 years. A scan of the May record keeping shows that two-thirds of the time May does not bring a 90°F reading to the Twin Cities. However, since 2000 the month of May has brought such a temperature reading on at least one day, 11 times, so about 50 percent. BTW there are only two Mays in the Twin Cities climate record that brought readings 100°F or greater. Those were in 1934 and 2018.

Twin Cities Almanac for May 20th:

The average MSP high temperature for this date is 71 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 52 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for May 20th:

MSP records for this date: highest daily maximum temperature of 94 degrees F in 2009; lowest daily maximum temperature of 45 degrees F in 1931; lowest daily minimum temperature of 31 degrees F in 1892; highest daily minimum temperature of 69 degrees F in 2009; record precipitation of 1.47 inches in 2017. A record snowfall of 3.0 inches in 1892.

Average dew point for May 20th is 47°F; the maximum dew point on this date is 69°F in 1974; and the minimum dew point on this date is 19 degrees F in 1954.

All-time state records for May 20th:

The state record high temperature for this date is 100 degrees F at Fairmont (Martin County) in 1934. The state record low temperature for this date is 16 degrees F at Embarrass (St Louis County) in 2002. The state record precipitation for this date is 4.83 inches at Winton (St Louis County) in 1970. Record snowfall is 4.8 inches at Virginia (St Louis County) in 1931.

Past Weather Features:

Many central counties in Minnesota reported snowfall over May 20, 1892. Some observers reported 1 to 3 inches, with morning temperatures in the 20s and 30s F. By afternoon temperatures warmed into the 50s F and the May sunshine rapidly melted all the snow.

May 20, 1934 was by far the warmest in state history with nearly half of Minnesota reporting afternoon temperatures in the 90s F. Pipestone, Redwood, Martin, and Nicollet Counties reached 100 degrees F. At Rochester the overnight temperature never dropped below 70°F.

May 20, 2002 brought frost to many parts of the state. Morning temperatures were below freezing as far south as Worthington and Caledonia. Up north, Brimson, Tower, and Embarrass all reported morning lows in the teens, and the afternoon high temperature at Grand Portage along Lake Superior only reached 40°F.


Temperatures will be much cooler than normal over the weekend with a chance for frost in some northern and central counties. Temperatures will remain cooler than normal Monday through Wednesday next week with small daily chances for widely scattered showers. A warm up to near normal temperatures will begin on Thursday and into Memorial Weekend temperatures will climate to above normal values.

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