May Wetness Continues

May Wetness Continues:

Widespread strong thunderstorms brought significant rains to much of the state this week on May 20 and 21, especially southern and northeastern Minnesota counties. Many climate observers reported from 1.25 inches to 2.50 inches from these storms, and a few places reported over 3 inches. With these storms, there were two tornadoes reported (near Fairmont and Winona), 34 reports of damaging winds (over 60 mph), and thankfully no large hail reports. Several long-term climate stations reported record-setting daily amounts of rain, including:

Duluth 1.42 inches
Brainerd 1.71 inches
Hibbing 1.76 inches
Tower 2.20 inches
Two Harbors 2.12 inches
Milan 3.78 inches
Artichoke Lake 2.26 inches
Red Wing 2.32 inches
Hastings 2.12 inches
Zumbrota 1.86 inches

Further details on the storms of May 20 and 21 may be found on the Minnesota State Climatology Office web site.

Average total rainfall for the month across the state is about 4 inches already but varies widely. For example, for example in northwestern Minnesota counties (Red River Valley area) the average rainfall for the month is 2.90 inches, but in south-central Minnesota it is over 5.50 inches. Forecasts for the balance of the month suggest that we will see at least 3 or 4 more rainy days, which could push our statewide average rainfall for May to close to 5 inches. There have been only 12 years in history where May has brought a statewide average rainfall of 5 inches or greater (1896, 1902, 1905, 1908, 1938, 1944, 1959, 1962, 2004, 2012, 2015, and 2022). So, this May could end up being exceptionally wet with respect to our long-term climate history.

The above normal rainfall this month has certainly replenished stored soil moisture values around the state. According to USDA Crop Condition reports earlier this week both topsoil and subsoil moisture conditions around the state are rated to be 85 percent to 95 percent adequate or surplus, a level not seen since 2019. At the University of Minnesota Southwestern Research and Outreach Center in Lamberton (Redwood County), store soil moisture in the top 5 feet is estimated to be close to 9 inches.

Drought has all but vanished from the Minnesota landscape with less than 9 percent of the state designated to be in Moderate Drought, primarily as a carry-over from last year. According to the NOAA Climate Prediction Center a wetter than normal weather pattern is expected to prevail across Minnesota through the first full week of June.

Weekly Weather Potpourri:

Thanks to transition to a La Nina episode expected to happen in the equatorial Pacific Ocean this summer, as well as warmer than normal sea surface temperature in the Atlantic Ocean, NOAA scientists are expecting a busy Atlantic Hurricane Season this year. NOAA says that “, 8 to 13 tropical storms are forecast to become hurricanes (winds of 74 mph or higher), including 4 to 7 major hurricanes (category 3, 4 or 5; with winds of 111 mph or higher). Forecasters have a 70% confidence in these ranges.”

The Weather Underground features a detailed story about the tornado that devastated Greenfield, IA this week, leaving 5 dead and 35 injured. It was upgraded to an EF04 storm (winds 175-185 mph) after a survey by National Weather Service personnel. One photo shows nothing but debris left from a building, except for the ATM machine.

This week’s AGU EOS Bulletin features an article about the escalating economic impacts of climate change. This study was published in the journal Nature. Researchers assessed the economic impacts of various climate extremes and found that worldwide income may fall as much as 19 percent by 2049, with wide geographic disparities in impacts.

MPR listener question:

With the multi-year drought all but over in Minnesota due to this wet spring, I wondered how often has drought persisted for more than two growing seasons in a row across parts of Minnesota, and with the changing climate oscillating between excessively wet and excessively dry are long, multi-year spells of drought likely to become very exceptional?

Answer:

Good question. From the study of drought persistence in Minnesota, it appears that the longest sequences of year-by-year drought occurred during these periods:

1921-1923
1929-1934
1936-1939
1987-1989
2020-2023

Wide swings in precipitation patters from excessively dry to excessively wet have allowed for relatively rapid drought recovery in the past. This was the case with the 1910, 1976, 2003, 2006, and 2012 drought years which were followed by wetter than normal years and rapid recovery. The droughts of the early 1920s, the 1930s, and the late 1980s, have taken multiple years to recover from (in terms of soil moisture recharge, lake levels and volume flows in our rivers). Our most recent drought which began in 2020 has persisted in parts of the state for four years, but this exceptionally wet spring has certainly all be alleviated it. This pattern of wide swings in moisture conditions may be indicative of our climate future.

Twin Cities Almanac for May 24th:

The average MSP high temperature for this date is 72 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 53 degrees F (plus or minus 7 degrees F standard deviation).
MSP Local Records for May 24th:

MSP records for this date: highest daily maximum temperature of 95 degrees F in 2010; lowest daily maximum temperature of 49 degrees F in 1893; lowest daily minimum temperature of 32 degrees F in 1925; highest daily minimum temperature of 72 degrees F in 2010, and record precipitation of 1.27 inches in 1937. There was a record snowfall of 0.1 inches in 1925.

Average dew point for May 24th is 48°F; the maximum dew point on this date is 71°F in 1989; and the minimum dew point on this date is 20 degrees F in 1934.

All-time state records for May 24th:

The state record high temperature for this date is 98 degrees F at Beardsley (Big Stone

County) in 1928. The state record low temperature for this date is 18 degrees F at Mora (Kanabec County) in 1988. The state record precipitation for this date is 4.91 inches at St Francis (Anoka County) in 2012. The state snowfall record is 1.7 inches at Northfield (Dakota County) in 1893.

Past Weather:

Frosts were common across much of central and northern Minnesota on the morning of May 24 in 1917. Frosts were reported as far south as Windom and Rochester, with morning lows in the 20s F across many northern counties. Newly emerged crops suffered from frost damage in some areas.

Strong thunderstorms brought heavy rains to western and central Minnesota on May 24 of 1939. Many observers reported 2 to 4 inches of rain. In portions of Todd County township roads were washed out by flash flooding.

May 24 of 2010 was arguably the warmest in state history. Over 40 climate stations reported afternoon high temperatures of 90°F or greater. Overnight low temperatures remained in the 70s F in many places.

Outlook:

Memorial weekend will start out sunny and dry in most places, then increasing clouds by Saturday night with chance for showers and thunderstorms on Sunday. Continued chance for showers on Monday, but then mostly dry and sunny for Tuesday and Wednesday. A chance for showers returns by Thursday.