Image credit: Minnesota State Climatology Office
After experiencing warm but very dry conditions across Minnesota in January and February of 2024, a more active pattern brought much wetter conditions to the state during the spring, along with continued warmth. Meteorological Spring, March through May, exceeded the 1991-2020 average (or "normal") precipitation across all of Minnesota, with about half the state exceeding normal precipitation by over 50%.
Sudden Shift from Dryness to Wetness
March actually began on a very dry note, with extreme warmth and very little precipitation. In the Twin Cities, a run of 33 days with no measurable precipitation began on February 16th and continued through March 20th, becoming the 2nd longest streak without measurable precipitation on record. During the first 20 days of the month, around 60 different observers in the National Weather Service Cooperative program recorded no measurable precipitation, at least one high of 70 degrees F, and five or more 60-degree F days. Indeed, March appeared to be extending the warm, dry, and snowless "Lost Winter" of 2023-24.
Beginning around March 21, however, a much more active pattern set up across the region. A sprawling winter storm March 23-27 dropped heavy snow and rain over a large area, effectively doubling seasonal snowfall and precipitation totals in many areas, and reversing the winter precipitation deficits caused by the prolonged winter dry spells. Each of Minnesota's five "first-order" stations ended March with above-normal precipitation, as did the southeastern 2/3 or so of the state.
From that point, right through the end of May, Minnesota had a steady diet of precipitating weather systems, generally coming every 3-5 days--sometimes arriving daily, and occasionally separated by a week or so. These were predominantly rain-making weather systems, and because Minnesota tended to be on the cooler side of the passing systems, the rain was typically steady and of light to moderate intensity. Heavier rains associated with thunderstorms began affecting the state towards the end of May, but most of the wet spell through May took place without significant flash flooding.
The proportion of the state with above-normal precipitation grew to about 90% during April, with only the far north and a small part of the southeast coming in dry. St. Cloud more than doubled its normal precipitation, as did many communities in central Minnesota, and also along the Red River in the northwest.
In May, the parade of wet systems continued, with mostly steady rains during the first three weeks or so of the month, but more thunderstorms and downpours arriving as the month ended. At least 95% of Minnesota saw above-normal precipitation, with areas all over the state receiving precipitation amounts that were more than 50% above normal.
Virtually the entire state of Minnesota had above-normal precipitation for the spring season, March through May. Many stations, in all regions of Minnesota, exceeded normal precipitation for the season by at least 50%. The largest proportional surplus at any station with a complete record was in Milan, along Highway 7 in extreme western Chippewa County, where the 13.68 inches of spring precipitation exceeded normal precipitation by 93%, or 6.60 inches.
Warmth
Each spring month in 2024 was warm at every station in Minnesota, and Rochester, S. Cloud, and the Twin Cities all finished the season in their all-time top-10s for warmth. With the exception of the record-setting heat in early March, however, the warmth was generally subtle, rather than extreme, and was not nearly as significant as the heat that had shaped the winter. Spring was generally 1-2 degrees F warmer than normal in far northern and northeastern Minnesota, but 2 to 4.5 degrees F warmer elsewhere in the state.
One thing that held the warmth back some appears to be the wetness itself! For instance, 47 out of 62, or 76% of the spring days without measurable precipitation in the Twin Cities were also warmer than normal for the date with just 24% breaking cool, meaning dry days were about three times more likely to be warm than cool. On those dry days, the temperature averaged 4.5 degrees F above normal.
By contrast, only 14 out of 30, or 45% of days with measurable precipitation in the Twin Cities were warmer than normal for the date, meaning that wet days were slightly less likely to be warm than cool. And on those wet days, the temperature averaged just 0.1 degrees F above normal. So spring was warm indeed, but it likely would have been even warmer without the switch to wet conditions.
KAB, June 3, 2024