Preliminary April Climate Summary:April was a roller coaster month climate-wise, starting out cool and wet, then warm and dry in the middle, and finally finishing cool and wet again.
Most observers report average monthly temperatures that are from 1 to23 degrees F above or below normal. The cooler than normal reports came primarily from northern communities while the warmer than normal reports came from the southern counties. Extreme temperatures for the month ranged from 86 degrees F at Wheaton (Traverse County) on the 15th to -13 degrees F at Seagull Lake (Cook County) on the 4th. A number of Minnesota climate stations reported new record high daily temperatures in the 70s F on the 4th, and record high daily temperatures in the 80s F on the 14th and 15th. Conversely a number of climate stations reported new record daily low temperatures on the 3rd, 4th, and 9th of April. Minnesota reported the coldest temperature in the nation on four dates during the month.
Precipitation for April was above normal for most areas of the state. Generally the eastern sections of the state received more precipitation than the western sections. The far northwestern counties and the far southeastern counties received the least amount of precipitation for the month. A number of observers reported over 3 inches of precipitation for the month, and a few reported over 4 inches. Nearly all of the measured snowfall occurred in the first two weeks of the month, ranging from 1 to 4 inches for most observers. Many communities in northeastern Minnesota measured over 10 inches and Gunflint Lake topped the list with 16.8 inches. Gunflint Lake also reported a new daily record snowfall of 6.5 inches on April 4th. In the northeast Isabella, Wolf Ridge, and Two Harbors reported maximum snow depths over 10 inches early in the month, while some southern counties reported no snow on the ground for any date during the month.
April lived up to its reputation for the windiest month on the Minnesota calendar with average wind speeds ranging from 12 to 15 mph and nearly half the days of the month producing peak wind gusts over 30 mph. Several observers reported days with wind gusts over 40 and 50 mph.
A brief tornado touchdown occurred in Faribault County on April 24th near Bricelyn with no reported damage.
As a result of no snow cover, absence of soil frost, and warm temperatures during mid-month Minnesota farmers accomplished earliest-ever planting of sugar beets, and a very early planting of corn, with over half of the 7 million acre crop planted by the last week of April.
Weekly Weather Potpourri:This week Deke Arndt from NOAA-NCEI writes about the Prairie Fire Season in the Southern Plains states. He provides a good review of climate conditions that produce relatively high fire danger there and the detection of fire scars in the landscape from satellite imagery.
Starting in mid-May NOAA researcher Cynthia Way will begin a three-month leave to join her boyfriend James Caple and row across the North Atlantic Ocean, between Cape Cod and Ireland, a journey of 3300 miles on a 24-foot boat. They will cross the ocean unsupported by a team, but with a satellite phone for communications. They hope to make the crossing in less than 60 days and will post briefings on a web blog named 1000leagues.
NOAA National Snow and Ice Data Center also reported this week that the earliest date ever for the melt season on the Southern Greenland Ice Sheet was detected over April 11-13 when temperatures soared into the 60s F in many places. The Summit Research Station on Greenland, at 10,496 feet on top of the ice sheet measured the highest ever April temperature of 20F on April 11th.
For teachers and science students Science Magazine offers several animations to show case Data Stories, and of course one of these is on the global temperature record, a feature that is nominated for the "People’s Choice Awards."
A paper published this week in Nature Climate Change correlates satellite measured amplified "greenness" (Earth's vegetation) with increased atmospheric carbon dioxide fertilization. Examining the satellite records from 1982-2015 NASA scientists are able to show the correlation in these features of Earth. They also acknowledge that other factors may be involved in this measured increase in greening.
MPR Listener Question:It has been very windy this spring, and in fact it seems wind speeds have been higher across southern Minnesota in recent years. Is this a result of climate change?
Answer:This question has not been comprehensively addressed by the atmospheric and climate science community yet. The few studies so far have yielded mixed results, suggesting a decline in mean wind speeds for some Midwest locations, and an increase in others. Analysis of the data over decades is difficult because the instruments used to measure wind speed by the NOAA-National Weather Service have changed over time. Fewer mechanical anemometers (spinning cups) are used and more sonic anemometers (the type that use sound wave attenuation to measure wind speed) are used today. Many projections made by climate models suggest that mean winds speeds may increase over time across the Great Lakes States, including Minnesota, but we have not yet validated this projection with real measured data. A good overview of wind measurements and trends in our region can be found from an Iowa State University publication.
Twin Cities Almanac for April 29th:The average MSP high temperature for this date is 64 degrees F (plus or minus 12 degrees F standard deviation), while the average low is 43 degrees F (plus or minus 8 degrees F standard deviation).
MSP Local Records for April 29th:
MSP weather records for this date include: highest daily maximum temperature of 92 degrees F in 1952; lowest daily maximum temperature of 35 degrees F in 1909: lowest daily minimum temperature is 22 degrees F in 1958; highest daily minimum temperature of 61 degrees F in 1952; record precipitation of 1.30 inches in 1991; and record snowfall of 6.6 inches in 1984.
Average dew point for April 29th is 37 degrees F, with a maximum of 66 degrees F in 1970 and a minimum of 7 degrees F in 1958 .
All-time state records for April 29th:The state record high temperature for this date is 93 degrees F at New Ulm (Brown County) in 1910. The state record low temperature for this date is 3 degrees F at Babbitt (St Louis County County) in 1958. State record precipitation for this date is 3.25 inches at Orr (St Louis County) in 1940; and record snowfall is 14.0 inches at Windom (Cottonwood County) in 1956.
Past Weather Features:Heavy thunderstorms brought record-setting rainfall amounts to western Minnesota over April 26-30, 1886. Farmers had to postpone planting small grains until the flood waters receded as many areas received 3 to 6 inches of rain.
Again in 1940 heavy thunderstorms brought abundant rainfall to many places over April 28-30. Several observers reported 2 to 3 inches and some small grain fields were washed out and had to be replanted.
On a statewide basis the warmest April 29th was in 1952 when dozens of communities saw record daily high temperature records set. Nearly every climate station in the state reported afternoon highs in the 80s F, while ten cities reported temperatures of 90 degrees F or higher. The temperature at Windom (Cottonwood County) never fell lower than 65 degrees F that day.
By far the coldest ever April 29th was in 1958. Nearly every climate station in the state reported record-setting cold temperatures. Many northern climate stations fell to single digit readings between 3°F and 9°F. As far south as Austin the temperature fell to just 18 degrees F. In some areas of the Red River Valley crop damage was extensive and some sugar beet fields, potato fields, and small grain fields had to be replanted.
A late season snow storm brought heavy snows to many parts of the state over April 29-30, 1994. Many climate states reported 6 to 12 inches of snowfall. Fortunately it was short-lived as temperatures climbed into the 50s F over the next several days.