HydroClim Minnesota for Early May 2019
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: May 9, 2019
What happened in April 2019:
- April 2019 was cool and damp for many places in Minnesota. However it was not as cold as April 2018. By far the wettest locations were across the south, boosted by a mid-month snow event. The cool weather caused lake ice out to progress generally a week behind historical medians.
[see: April 2019 Precipitation Total Map | April 2019 Precipitation Departure Map | April 2019 Climate Summary Table | April 2019 Percent of Normal Precipitation Map]
- The main weather event of April 2019 was the spring storm and blizzard, April 10-12, 2019. Precipitation totals of 1-2 inches covered the majority of Minnesota, with isolated areas in western and southwestern Minnesota receiving higher amounts. Over 60% of Minnesota received at least 6 inches of snow, with accumulations ranging from just a trace near the Iowa border, to nearly 20 inches in western Minnesota. In the Twin Cities, the final total of 9.8 inches ranked as the 5th largest April snowstorm on record. In parts of southwestern Minnesota, including Marshall, the double-digit snowfall totals cemented this winter as the snowiest on record.
[see: Spring Storm and Blizzard, April 10-12, 2019]
- The snowy mid-April caused much below normal temperatures. However, there were enough mild episodes for the second half of April to tug the monthly departure values closer to normal but not enough to overcome the overall coolness. The coldest temperature for April 2019 was 4 degrees on April 4, east of Ely and the warmest temperature found was 86 degrees at Windom, Winnebago and Waseca on April 22.
[see: April 2019 Climate Summary Table | 2019 April Departure from Normal Temperature Map
Where we stand now:
- Seasonal precipitation totals so far (April 1 through May 7) ranked well above the historical medians over central, southern and much of northern Minnesota, with below the median across the northwest.
[see: Seasonal Precipitation, Percent Normal and Ranking Maps]
- The final snow depth map of the season was produced on April 25. Snow depths on that map was up to 12 inches across the Lake Superior highlands.
[see: Snow Depth Map: April 25, 2019]
- The U. S. Drought Monitor map released on May 9 shows no drought designation in the state. Minnesota has been free of any drought designation since February 26 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 in southern and central Minnesota. Streamflows in the north range from normal to above normal. Rivers remain quite high, especially in the south, due to continued heavy precipitation that has continued into early May.
[see: USGS Stream Flow Conditions]
- Water levels on most Minnesota lakes vary depending on lake and location in the state. Mille Lacs lake level for April was still affected by ice. The ice left Mille Lacs on April 28. On May 9, Minnetonka was at 929.87 with 250 cfs flowing through Grays Bay Dam. White Bear Lake was at 925.06 feet on May 9, a rise of 1.73 feet from one year ago and a rise of 6.22 feet from the record low of 918.84 measured January 10, 2013. The last time White Bear Lake was above 925.06 feet was in July 2003. Rainy Lake is at the higher end of the normal band for the time of year. Lake of the Woods is in the middle of the normal band and on May 8th was at 1058.96ft. This is in the 45th percentile for that time of year. Lake Superior was at 602.66 feet on May 3, thirteen inches higher than the monthly average for May and one inch away from the highest monthly average of record for May. All the Great Lakes are well above historical averages for May.
[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]
- Spring crop planting was behind in late April and May due to cool and damp weather conditions. However, the occasional decent weather day saw much field activity in the south. Corn planted for early May was well behind the five year average and matched the progress in early May 2018. The Agricultural Statistics Service reported on May 5 that topsoil moisture supplies across Minnesota are 0 percent Very Short, 0 percent Short, 58 percent Adequate, and 45 percent Surplus.
[see: Agricultural Statistics Service Crop Progress and Condition]
- The potential for wildfires on May 9, rated by DNR Forestry as ranging from Moderate in northwest, west central and southeast Minnesota, with Low for southwest through northeast Minnesota.
[see: Fire Danger Rating Map]
- Lake ice out was running a week behind the median for April into early May, but earlier than in 2018. Lakes have been sluggish to shed the last of their ice in far northeast Minnesota. As of May 9, some lakes in Cook County still had ice on them. Larger lakes in the state are ice free. There was still some ice on Lake of the Woods. Median lake ice out for Lake of the Woods is May 3.
[see: 2019 Lake Ice-Out Dates | DNR Conservation Officer Reports]
- The May precipitation outlook has above normal precipitation for central and southern Minnesota, with equal chances for above, below and normal precipitation across the north. May precipitation normals range from just over two inches in northwest Minnesota to just less than four inches in southeastern counties. The historical probability of measurable precipitation for any given day in May ranges from 25 percent in the northwest to near 40 percent in the southeast.
[see: Climate Prediction Center 30-day Outlook | May Precipitation Normal Map]
- The outlook for May calls for a continuation of below normal temperatures across the state and an even better chance over the Dakotas. Normal May high temperatures are in the low to mid-60s early in the month, rising to the low to mid-70s at month's end. Normal May low temperatures are in the mid-30s to near 40 to start the month and climb to the mid-40s to low 50s as the month ends.
[see: Climate Prediction Center 30-day Outlook | May Temperature Normal Map]
- The 90-day precipitation outlook for May through July indicates equal chances of below-normal, near-normal, or above-normal conditions for most of Minnesota, and a tilt towards above-normal conditions in southwestern counties. The May through July temperature projection indicates equal chances of below-normal, near-normal, or above-normal conditions statewide, woth a perhaps a slight tilt to above normal temperatures in Cook County.
[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.
[see: National Weather Service - North Central River Forecast Center]
From the author:
- May 2019 was not the end of the snowfall for the season. May 8-9, 2019 was one of the largest May snowstorms in Minnesota history and dumped up to ten inches of snow in Duluth. [see: Record May Snow and Soaking Rains, May 8-9, 2019]
Upcoming dates of note:
- May 16: National Weather Service releases 30/90 day temperature and precipitation outlooks
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Pete Boulay, DNR Climatologist