Rollercoaster Temperatures and Staying Wet:
After seeing temperatures in the 80s F back on April 5-6, daytime high temperatures this week were generally in the 30s and 40s F across much of the state, with overnight lows in the teens and twenties. This translates to about 12 to 15 degrees F colder than normal. In some areas of the state new record low temperatures were established on April 21 and 22. Among those set on April 21 were:
Caledonia 22°F
St Cloud 21°F
Redwood Falls 20°F
Zumbrota 19°F
Browns Valley 18°F
Madison 17°F
Grand Portage and Preston 16°F
Pipestone 12°F
Then on April 22nd a few more record lows were:
Browns Valley 19°F
Long Prairie 18°F
Pipestone 15°F
It is somewhat remarkable that record low temperatures were set without snow cover, but the atmosphere has been exceptionally dry this week, with afternoon relative humidity values ranging from 15 to 25 percent. This allows the temperatures to cool off dramatically at night.
The wide swings in temperature have somewhat balanced each other as mean monthly temperature for April so far is only about 1 degree warmer than normal. Historically the months of March, April, and May are noted for wide swings in temperature as different air masses, ranging from the dry, southern plains to the north Canadian tundra can alternate across Minnesota.
Continued rainfall this month has helped shrink the area of drought in Minnesota. According to the US Drought Monitor the only areas of the state that are still categorized in Severe Drought are portions of Kittson and Marshall Counties in the far northwest. Other areas designated to be in Moderate Drought have shrunk too. Portions of 9 Minnesota counties have reported over 4 inches of precipitation so far this month. Portions of south-central and southeastern Minnesota would welcome more rain this month, as they have been left shy of normal.
Weekly Weather Potpourri:
NOAA features a very interesting article about the new climate normals that are expected to be released in May for the USA climate stations. These will be the 30 year averages from 1991-2020 and available for hourly, daily, monthly, and annual data. For Minnesota the new normals are expected to show continued warming of temperatures, though with mixed signals from month to month (some cooler and some warmer). They are also expected to show the upward trend in annual precipitation for most places in the state.
The Weather Channel web site features an article this week “9 Trends That Show the Harsh Reality of Climate Change.” It is an interesting read and highlights the various ways climate change is having an impact already, with ample scientific evidence to back it up.
The AGU EOS Bulletin this week features an article about a new NASA program that will utilize satellite data and partner with epidemiologists to study air pollution in more detail and better determine health risks to various populations. The program will get underway by the year 2022.
MPR listener question:
I am planting shelter vegetation (windbreaks) around my large garden in Faribault, MN this spring and I wondered what the prevalent wind directions are that I must consider. Can you tell me?
Answer:
Yes, indeed. The wind climatology for Faribault suggests that windbreaks should be oriented to protect from northwest winds and winds from the south-southeast. Dogwoods and lilacs make species for windbreaks, as well as smaller trees like chokecherry or crabapple. You can get more information on wind climatology (wind roses) at this web site from Iowa State University. And you can get more recommendations on windbreaks from the University of Minnesota Extension at their web site:
Twin Cities Almanac for April 23rd:
The average MSP high temperature for this date is 62 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 41 degrees F (plus or minus 8 degrees F standard deviation).
MSP Local Records for April 23rd:
MSP records for this date include: highest daily maximum temperature of 86 degrees F in 1990; lowest daily maximum temperature of 35 degrees F in 1910; lowest daily minimum temperature of 19 degrees F in 1910; highest daily minimum temperature of 65 degrees F in 1925; record precipitation of 0.87 inches in 1948. Record snowfall is 1.6 inches in 1988.
Average dew point for April 23rd is 34°F; the maximum dew point on this date is 66°F in 1908; and the minimum dew point on this date is 2 degrees F in 2015.
All-time state records for April 23rd:
The state record high temperature for this date is 94 degrees F at Granite Falls (Yellow Medicine County) in 2009. The state record low temperature for this date is -1 degrees F at Grand Rapids (Itasca County) in 1918. The state record precipitation for this date is 4.22 inches at Marshall (Lyon County) in 2001. Record snowfall is 12.0 inches at Meadowland (St Louis County) in 1968.
Past Weather Features:
April 23, 1909 brought a taste of winter to Minnesota. With ample snow on the ground in many areas, morning low temperatures dipped into the single digits in the north and teens in the central and south. The daytime high at Campbell (Wilkin County) only reached 27°F.
A late season winter storm brought a mixture of rain, sleet, and snow to Minnesota over April 23-34, 1968. Portions of southern Minnesota saw lightning, thunder, and 1.5 to 3.00 inches of rain, while portions of northern Minnesota received heavy, wet snow. The Iron Range reported 10 to 14 inches of snowfall.
One of the most remarkable drops in temperature occurred on this date in 1980. Hawley, in Clay County east of the Fargo-Moorhead area, had recorded an all-time high April temperature of 101 degrees F on April 22nd. However, winds shifted around to the north and brought in a cold Canadian air mass dropping the temperature to 30 degrees F on the morning of April 23rd. This 71 degrees F change in temperature over a 24-hour period is one of the largest in the Minnesota historical records. The month of April that year saw the onset of a spring drought in the Red River Valley.
Outlook:
Partly cloudy but cool on Saturday with below normal temperatures. Increasing cloudiness late in the day, then on Sunday a chance for rain or snow showers. Warming Monday and Tuesday, but chances for showers each day. Generally drier the remainder of the week with near normal temperatures.
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