Mixed Start to the Month of April

Mixed Start to the Month of April:

The first two days of April brought mixed weather to the state. Many parts of southern and eastern Minnesota enjoyed mild, warmer than normal temperatures (commonly highs in the 60s F). But in the west and northwest (Red River Valley) a winter storm brought a mixture of significant precipitation, including rain, ice, and snow, with colder than normal temperatures. Roads were snow covered in some areas, while other areas reported ice on the roads late on Thursday afternoon and into early Friday morning. Wind Chill values dropped into the teens and single digits and travel was difficult in some areas. Snowfall amounts in the western counties ranged from 1 inch to 4 inches in many spots, with Crookston reporting 9 inches and Karlstad reporting 11 inches.

A Climate Scientist Blogs on the Coronavirus Pandemic and Our Response:

Dr. Ben Santer is an esteemed climate scientist and Member of the National Academy of Science. He has lectured at the University of Minnesota a number of times, and I have known him for over 15 years. I trust both his science and his perspectives on the challenges before us as we cope with COVID-19 pandemic. His recent blog in Scientific AmericanMagazine (online) is well worth the read.

There are many lessons from coping with the COVID-19 pandemic that apply to how we should cope with climate change as well. Two quick points he makes: Scientific ignorance can be fatal in some situations; and a political leader should not assume the mantle of expertise in areas where he or she has none. We need to invoke more trust in science and act to protect ourselves and future generations.

April 2-3, 1982 All Four Seasons Were Sampled:

Following one of the snowiest winter seasons in state history (over 90 inches in the Twin Cities), April 2, 1982 brought the first severe weather day of the spring season to western Minnesota. Many portions of southwestern Minnesota were under a severe thunderstorm watch that day. Bright sun, strong southerly winds, recent loss of snow cover, accelerated the daily temperature rise, producing afternoon highs in the 70s F. It reached 78°F at Lamberton, 77°F at Worthington, 75°F at Windom, and 68°F at St Peter, all readings about 15-20 degrees F above normal.

Atmosphere instability brought by the clash of an air mass from the southwestern USA and an air mass which dropped down from Alberta, Canada caused huge billowing clouds and thunderstorms to form by late afternoon. No tornadoes, but some severe thunderstorms, with hail developed that afternoon dropping from 1 to 1.5 inches of rainfall in many places. Later that night the precipitation turned to snow, dropping an inch at Luverne and Pipestone, but much more in northern communities, including a statewide record of 14 inches at Kettle Falls in Voyageurs National Park.

Strong northwest winds accompanied the cold front and temperatures dropped dramatically overnight, so that 12-14 hours later on the morning of April 3rd Lamberton reported 7°F, Windom 10°F, Worthington 12°F, and St Peter a record low of just 4°F. All of these climate stations saw a record drop of 64 to 71 degrees F in a 14-hour period.

Weekly Weather Potpourri:

The Joint TyphoonWarning Center was tracking two tropical cyclones this week: Cyclone in the South Indian Ocean, southeast of Diego Garcia, was expected to grow stronger but remain out to sea; and Cyclone Harold located in the South Pacific east of Australia was also expected to grow stronger but largely remain out to sea.

The BBC Weather Centre this week featured a story about how measured air pollution and atmospheric carbon dioxide have both shown significant drop-offs during the global pandemic lockdown in many nations. These declines are especially significant in nitrogen dioxide as well as small particulate matter.

MPR listener question:

I have heard your presentation on climate change in Minnesota many times and you have shown that the state is getting more precipitation now than ever, especially cited the month of April. How much has average monthly precipitation changed in April here in the Twin Cities?

Answer:

Indeed, of all months of the year April shows one of the largest changes. For the 1931-1960 period in the Twin Cities average April precipitation was 1.84 inches. Over the most recent 30- year period the average is 2.94 inches, over a 59 percent increase. Generally other months also show an increase in precipitation but mostly not of that steep magnitude.

Twin Cities Almanac for April 3rd:

The average MSP high temperature for this date is 51 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 32 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for April 3rd:

MSP records for this date include: highest daily maximum temperature of 80 degrees F in 1921; lowest daily maximum temperature of 24 degrees F in 1874; lowest daily minimum temperature of 9 degrees F in 1954; highest daily minimum temperature of 52 degrees F in 1921; record precipitation of 0.84 inches in 1974. Record snowfall is 5.9 inches also in 1974.

Average dew point for April 3rd is 26°F; the maximum dew point on this date is 58°F in 1956; and the minimum dew point on this date is -6°F in 1995.

All-time state records for April 3rd:

The state record high temperature for this date is 86 degrees F at Beardsley (Big Stone County) in 1929. The state record low temperature for this date is -19 degrees F at Big Falls (Koochiching County) in 1954. The state record precipitation for this date is 3.05 inches at Farmington (Dakota County) in 1934. Record snowfall for this date is 14.0 inches at Kettle Falls (St Louis County) in 1982.

Past Weather Features:

There was a very warm start to April in 1921. On the 3rd of the month many climate stations reported afternoon highs in the 70s F, while portions of Brown, Big Stone, Waseca, Lac Qui Parle, and McLeod Counties reached the 80s F. Some farmers were seen plowing their fields.

A slow-moving winter storm brought mixed precipitation to the state over April 1-3, 1934. It was one of the most significant storms of that drought year in Minnesota. Many areas of the state received between 1 and 2 inches of precipitation, while Farmington (Dakota County) recorded a state record amount on April 3rd of 3.10 inches. In northern counties 4-9 inches of snowfall was reported.

The coldest April 3rd in state history was in 1954. Most observers in the state reported a morning low temperature in the single digits, while there were scores of subzero temperature readings in the northern counties where there was still a good deal of snow on the ground. The temperature never rose higher than 13°F at Detroit Lakes (Becker County) that day.

Outlook:

Though starting out cooler than normal, the weekend will be most sunny. Temperatures will warm to above normal on Sunday and likely stay that way through Wednesday of next week. There will be a chance for showers by Tuesday and Wednesday with perhaps a scattered thunderstorm or two, before returning to cooler and drier weather towards the end of next week.