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 3, 2013 (released one day late)
What happened in April 2013:
- April precipitation totals were well above historical averages in the eastern one-half of Minnesota, near to below historical averages for the western one-half of the state. For many southeast Minnesota counties, monthly precipitation totals topped the long-term average by more than three inches, erasing drought concerns in those areas. Many observers reported measurable precipitation on more than 20 days during the month. Some observers reported precipitation on 10 or 11 consecutive days.
- Ten winter storm warnings and numerous winter weather advisories were issued for Minnesota counties by the National Weather Service during the course of the April. Frequent, and often heavy, storms piled up snowfall totals to record or near-record levels at many locations. Historical average monthly snowfall totals range from two inches in southern Minnesota to six inches in northern counties. In many Minnesota communities, April 2013 monthly snowfall totals exceeded 12 inches. Numerous locales reported monthly snowfall totals in excess of 24 inches. The focal point for the heaviest of the April snowstorms was northeast Minnesota, particularly Duluth, where April snowfall reached historic levels. The monthly snowfall total at Duluth's International Airport was an astounding 50.8 inches. Not only did this top the previous April record by nearly 20 inches, it was Duluth's snowiest month ever for any month of the year. The April snow and cold snarled roads, delayed agricultural field work, canceled outdoor events, and postponed natural signs of spring by many weeks.
- April average monthly temperatures in Minnesota were six to ten degrees below the historical average. It was Minnesota's third consecutive month of below-average monthly temperatures. Extremes for the month ranged high of 85 degrees on the 28th at St. James (Watonwan County) to a low of -14 degrees at Embarrass (St. Louis County) on the 20th. Hundreds of records were set during the month for coldest maximum and coldest minimum temperatures. A multitude of all-time minimum temperature records were set on April 20, including the -14 degree reading at Embarrass. This was the coldest temperature ever recorded in Minnesota on April 20 as well as the state’s coldest temperature ever observed in the second half of April. The Twin Cities reached 60 degrees for the first time on April 26, the second latest date ever for reaching that spring milestone. On a statewide basis, it was the fifth coldest April of the modern record.
Where we stand now:
- Year-to-date precipitation totals top historical averages in nearly all areas except for sections of southwest and northwest Minnesota. 2013 year-to-date precipitation totals exceed historical averages by two to five inches in many communities.
- The U. S. Drought Monitor, released on May 2, places portions of northwest, central and southwest Minnesota in the Severe Drought category. Much of the rest of Minnesota is deemed to be in Moderate Drought or Abnormally Dry. In total, 15 percent of Minnesota's landscape is rated in the Severe Drought category, a substantial improvement over early April when 67 percent of Minnesota was experiencing Extreme or Moderate drought. The U. S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc) are based on several indicators.
- A substantial snow cover remains on the ground in Koochiching and northern St. Louis counties, and along the Lake Superior highlands. Snow is deeper in the wooded areas. Snow cover has returned to the landscape in southeast Minnesota in the wake of the historic May snow event.
- The U.S. Geological Survey and the Minnesota DNR report that stream discharge values are above historical medians in many locations. The delayed spring melt runoff is skewing these statistics somewhat upward. Many locations along the Red River and its tributaries are reporting Moderate to Major flooding. A few locations along the Upper Mississippi River and the Long Prairie River also report Moderate flooding. The affected communities in all basins were well prepared and few impacts are reported. The flooding along the Red River has been well below anticipated levels because of a nearly ideal melt scenario.
- Water levels on most Minnesota lakes remain low due to the dry summer and autumn of 2012. However, lake levels are responding upward to spring snowmelt runoff and precipitation. Lake Superior's water level is approximately 14 inches lower than its historical average for this time of year.
- In their April 29 report, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 2% Very Short, 15% Short, 64% Adequate, and 19% Surplus across Minnesota. Subsoil moisture was said to be 50% Very Short or Short. Soil moisture measurements made recently at University of Minnesota Research and Outreach Centers indicated improving conditions in the soil profile in southern Minnesota.
- Ground frost still exists in some northern Minnesota locations. Typically the soil thaws from both top and bottom, leaving a frozen lens around 12 to 18 inches below the surface to thaw last.
- Lakes in the northern two-thirds of Minnesota remain ice covered. Southern Minnesota lakes that have lost their ice are reporting ice-out dates two to three weeks later than the historical median date. In some cases, lake ice-out dates are the latest on record. For many northern Minnesota lakes there is a very real possibility that ice cover will still be in place for the May 11 Minnesota Fishing Opener. This marks a sharp contrast with 2012 when Minnesota's lakes lost their ice remarkably early.
- The potential for wildfires is currently rated by DNR Forestry as Moderate throughout much of the northern one-half of Minnesota. Elsewhere, the fire danger rating is deemed to be Low. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
- The May precipitation outlook tilts towards a higher probability of above-normal condition in southeast Minnesota. Elsewhere across the state, the outlook offers equal chances of below-normal, near-normal, or above-normal conditions. 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.
- The May temperature outlook favors below-normal conditions in the northern one-third of Minnesota, and equal chances of below-normal, near-normal, or above-normal conditions elsewhere in the state. 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.
- The 90-day precipitation outlook for May through July offers equal chances of below-normal, near-normal, or above-normal conditions everywhere in Minnesota. The May through July temperature projection also projects equal chances of below-normal, near-normal, or above-normal conditions.
- 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
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Greg Spoden, DNR Climatologist