HydroClim Minnesota for Early April 2018

A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the first Thursday of the month.

State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: April 6, 2018

What happened in March 2018:

  • March monthly precipitation totals were generally below historical averages across the northern one-third of Minnesota and southeast Minnesota. March precipitation totals were around one inch below normal in many northeast and southeast locales. Precipitation was near to slightly above normal over western Minnesota. Two areas stand out with well-above normal precipitation totals. Lyon County in southwest Minnesota in particular was hit by two heavy snowfalls during the month. Also locations in Otter Tail County had monthly snowfall totals of 20 inches or more in a series of snowstorms.
    [see: March 2018 Precipitation Total Map  | March 2018 Precipitation Departure Map  | March 2018 Climate Summary Table  |  March 2018 Percent of Normal Precipitation Map]
  • A significant winter storm dumped snow over a large area of Minnesota on March 4-6. Northwest Minnesota saw a heavy band of snow from Hallock to Park Rapids and Wadena. Snowfall totals were 12-18 inches in the Park Rapids area. Another heavy band of snow fell in a swath in southern Minnesota from Canby and Marshall, eastward to Rochester. One of the larger snow totals found with this storm in southwestern Minnesota was 12 inches at Minneota in Lyon County. One of the higher totals in southeast Minnesota was 8.2 inches at Theilman in Wabasha County. Blowing and drifting accompanied the snow.
    [see: Winter Storm of March 5-6 2018]
  • Another heavy snowfall hit southwest and south central Minnesota on the evening of March 23 into the morning of March 24. There was an extremely sharp cut off to the snow northeast of the heaviest band. Marshall in Lyon County saw 13 inches with five inches at Mankato and eight at Albert Lea.
    [see: Heavy Snow Summary - March 23-24, 2018]
  • March had a cold finish. This was enough to tug the average monthly temperatures to slightly below historical averages at most Minnesota reporting stations. Monthly temperatures ranged from about two degrees below normal to one degree above normal. The statewide average was .9 (nine tenths) of a degree below normal. March 2018 finished .4 degrees below normal in the Twin Cities. It was the 2nd month in a row for below normal temperatures in the Twin Cities. Extremes for March ranged from a high of 55 degrees F at Winona Dam on the 1st, to a low of -15 degrees F near Ely on March 10.
    [see: March 2018 Climate Summary Table  |  2018 March Departure from Normal Temperature Map

Where we stand now:

  • As March turned into April, winter did not heed the calendar.  By April 5, snow covered many sections of Minnesota. The snow depth rank was in the 99th percentile over much of central and southern Minnesota. Significant snow depth persisted across northern Minnesota and gave people a chance for some late season winter recreation opportunities.
    [see: MNDNR April Snow Depth Maps  |  NWS Snow Depth Estimation Map  |  Midwest Regional Climate Center Snow Depth Map]
  • The U. S. Drought Monitor map released on April 3 shows a small pocket of Moderate Drought over Koochiching County surrounded by an area of Abnormally Dry Conditions . There is also a small area of Abnormally Dry Conditions in far northwest Minnesota and west central Minnesota. The U.S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc.) are based on several indicators.
    [see: Drought Conditions Overview]
  • The U.S. Geological Survey reports that stream discharge values are mostly affected by ice. Streamflows are near historical medians along the Mississippi and Minnesota River. Ice is affecting many gages along the Red River and many of its tributaries.
    [see: USGS Stream Flow Conditions]
  • In their first report of the 2018 growing season, the Agricultural Statistics Service reported that topsoil moisture across Minnesota was 0 percent Very Short, 2 percent Short, 62 percent Adequate, and 36 percent Surplus.
    [see: Agricultural Statistics Service Crop Progress and Condition]
  • The potential for wildfires is currently rated by DNR Forestry as Low across the entire state. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
    [see: Fire Danger Rating Map]
  • Frost persists in the soil in nearly all Minnesota locales. The top few inches did begin to thaw in central and southern Minnesota in March, especially in areas cleared of snow. The cold start of April put an abrupt end to any excessive thawing.  On April 5, the frost depth is 45 inches of frost in the ground at Grand Forks, 30 inches in the ground at Long Prairie and between nine and 21 inches in the Twin Cities Metro Area.
    [see: Corps of Engineers Snow, Ice, Frost Data  |  National Weather Service Frost Depth Data  |  MnDOT Road Frost Depths]
  • As of April 6, all lakes in Minnesota are still ice covered. There are reports of some thawing ice near the shores of lakes in southern Minnesota and in areas that have moving water. The progress of ice out is currently about ten days behind the historical average. In 2017 at this date, lakes were two weeks head of historical averages.
    [see: 2018 Lake Ice-Out Dates  |  DNR Conservation Officer Reports]

Future prospects:

  • The April precipitation outlook leans towards above normal precipitation across northern and central Minnesota. April precipitation normals range from one and one-half inch in northwest Minnesota to around three inches in southeast counties. The historical probability of measurable precipitation for any given day in April ranges from 20 percent in the far northwest to 35 percent in the southeast.
    [see: Climate Prediction Center 30-day Outlook  |  April Precipitation Normal Map]
  • The April temperature outlook favors below normal temperatures over the entire state. Normal April high temperatures are in the mid to upper 40s early in the month, rising to the low 60s by month's end. Early-April normal low temperatures are near 20 in the north, near 30 in the south. By month's end, low temperatures average in the mid-30s in the north, near 40 in the south.
    [see: Climate Prediction Center 30-day Outlook  | April Temperature Normal Map]
  • The 90-day precipitation outlook for April through June indicates above-normal conditions for all of Minnesota. The April through June temperature projection favors equal chances for above, below and normal conditions.
    [see: Climate Prediction Center 90-day Outlook]
  • The National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. These products address both high flow and low flow probabilities. The potential flooding risk is a greater than an even chance for some minor flooding over parts of the Minnesota, the Red River of the North and the upper reaches of the Mississippi. A few locations have a risk of moderate flooding including Montevideo on the Minnesota River and Fargo on the Red River of the North. One location has a risk of major flooding and that is at the Cottonwood River at New Ulm. During the month of March, much of the snowpack was lost to a very gradual snowmelt, but snow cover has increased again in early April.
    [see: National Weather Service - North Central River Forecast Center]

From the author:

  • The first week of April is shaping up to be one of the coldest starts to April when compared to past weather records. St. Cloud had a low temperature of zero degrees F on April 5, the coldest temperature for so late in the season. The Twin Cities had a low temperature of eight degrees F on April 4, the fifth coldest April temperature on record. It will be one of the later ice out seasons for lakes in southern Minnesota. Median dates of ice out for those lakes is the last week of March or the first week of April. The median date of ice out for the larger lakes in central Minnesota is mid-April. For the far northern lakes the median date of ice free is the last week of April or the first week of May. It is too early to tell at this point which lakes may be ice covered for the Minnesota Fishing Opener on May 12.

Upcoming dates of note:

  • April 19: National Weather Service releases 30/90 day temperature and precipitation outlooks

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Pete Boulay MNDNR Climatologist

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