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: June 2, 2017
What happened in May 2017:
- There was a sharp division between wet and dry conditions in Minnesota. Northeastern, central and southern Minnesota saw a surplus of precipitation, while the north central and northwest parts of the state saw very little rainfall during the month. The wettest locations were in southeast Minnesota where Altura in Winona County saw 10.29 inches in May, 2017 or 6.42 inches above normal. half of this precipitation came with one event during the evening of May 15th where 4.94 inches fell. One of the more drier locations was at Camp Norris, in Lake of the Woods County. The preliminary statewide average was 4.32 inches or .97 inches above normal.
[see: May 2017 Precipitation Total Map | May 2017 Precipitation Departure Map | May 2017 Climate Summary Table | May 2017 Percent of Normal Precipitation Map]
- There was one heavy rain event of note for the month. Severe thunderstorms developed during the afternoon hours of May 15th and waves of thunderstorms continued across central and southern Minnesota through the 16th. The heaviest rains fell over southeast Minnesota where two to four inches fell in parts of Olmsted, Wabasha and Winona Counties. The highest rainfall reported was 4.94 inches near Altura in Winona County. The heavy rains caused the Whitewater River to peak in the Elba area in the minor flood category before receding.
[see: Heavy Rains: May 15-16]
- Severe storms were infrequent during the month of May in Minnesota. There were two weak tornadoes in southeast Minnesota on May 17, to bring the total tornado count for the year at five.
[see: Severe Thunderstorms and Tornadoes of May 17]
- May 2017 brought the streak of above average months to a screeching halt. For the first time since August 2015, the average monthly temperature finished below normal in places like the Twin Cities (58.5 degrees or .6 degrees below normal) and St. Cloud (54.9 degrees or 1.6 degrees below normal) The preliminary average temperature for Minnesota for May 2017 is 54.4 degrees and 1.7 degrees below normal. The warmest temperature found in Minnesota so far for May was 90 degrees on May 15 at Waseca and the coldest reading was 21 degrees on May 5 at Brimson.
[see: Warm Streak Ends | May 2016 Climate Summary Table | 2017 May Departure from Normal Temperature Map ]
Where we stand now:
- The U. S. Drought Monitor map released on May 30, depicts portions of northwestern, north central and west central Minnesota as Abnormally Dry. The map shows no other areas in Minnesota in a dryness category. May 2017 was the first month since August 2016 where there was any dryness category located in the state. 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 above to much above normal historical medians across southern Minnesota, with the high flows in response to the wet May. There were generally normal streamflows in central and northeast Minnesota with some below normal stream discharge values in northwest Minnesota.
[see: USGS Stream Flow Conditions]
- Water levels on most Minnesota lakes vary depending on lake and location in the state. Mille Lacs was above the median lake level for May. On June 2 Minnetonka was at 929.56 with 150 cfs flowing through Grays Bay Dam. White Bear Lake was at 923.59 feet on June 2, a rise of 1.3 feet from one year ago and a rise of 4.75 feet from the record low of 918.84 measured January 10, 2013. The highest recent level for White Bear Lake was 923.63 on May 28. This is the highest level for White Bear Lake since June 16, 2006. Rainy and Lake of the Woods are in the median range for May. Lake Superior was at 602.46 feet on June 2, seven inches higher than the monthly average for April.
[see: Mille Lacs Lake Water Level | Lake Minnetonka Water Level | White Bear Lake Water Level | Lake of the Woods Control Board Basin Data | Corps of Engineers Great Lakes Water Levels]
- The Agricultural Statistics Service on May 30 reported that topsoil moisture across Minnesota is 0 percent Very Short, 1 percent Short, 76 percent Adequate, and 23 percent Surplus. Soil moisture readings at Lamberton on May 15 have the moisture profile close to historical averages.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research & Outreach Center (Lamberton)]
- The potential for wildfires is currently rated by DNR Forestry as Low across much of Minnesota, with the exception of High in the far northwest counties. Wildfire danger remains in the northwest due to the trend in drier conditions. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
[see: Fire Danger Rating Map]
- The June precipitation outlook leans towards equal chances for below, above and normal precipitation across Minnesota. June precipitation normals range from just over three inches in northwest Minnesota to about five inches in southeastern counties.
[see: Climate Prediction Center 30-day Outlook | June Precipitation Normal Map]
- The June temperature outlook has equal chances for below, normal and above normal temperatures throughout Minnesota. Normal June high temperatures are in the low to mid 70s early in the month, rising to around 80 by month's end. Normal June low temperatures are in the low 50s to start the month, and rise to around 60 as the month ends.
[see: Climate Prediction Center 30-day Outlook | June Temperature Normal Map]
- The 90-day precipitation outlook for June through August indicates equal chances of below-normal, near-normal, or above-normal conditions over Minnesota. The June through August temperature projection favors equal chances for below-normal, near-normal or above-normal conditions statewide, with the exception of the far northeast where there is a slight tilt to above normal temperatures.
[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 major tributaries (St. Croix, Minnesota and Mississippi) are showing a general downward trend from the higher levels seen in mid to late May.
[see: National Weather Service - North Central River Forecast Center]
From the author:
- The cool and damp weather of early to mid-May slowed crop planting progress in Minnesota, but the warmer and drier trend over the past week has helped planting and growing conditions. Crabapple trees bloomed in Maplewood, just north of St. Paul on May 7, a few days later than the past two years and two weeks earlier than 2014. Lilacs just north of St. Paul had a prolonged bloom period with the peak around May 13, a few days later than the last two years and fourteen days earlier than 2014. Soil temperatures on the U of M St. Paul campus have warmed in early June at the 4 inch level under bare soil to near 80 degrees in the day to the upper 50's at night. If you have any questions or comments about the HydroClim Newsletter, please let me know.
Upcoming dates of note:
- June 15: National Weather Service releases 30/90 day temperature and precipitation outlooks
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Pete Boulay, DNR Climatologist