October 2011 was an exceptionally dry month across Minnesota. This marked the third consecutive month of widespread rainfall shortfalls. For many locations, October rainfall totals failed to reach one inch. In nearly all counties, monthly precipitation fell short of the historical average by one to two inches. In some locales, it was among the driest Octobers of the modern record.
Monthly mean temperatures for October 2011 were very warm, topping the historical average by four to seven degrees across Minnesota. Preliminary data indicate that October 2011 will rank among the warmest ten Octobers in the historical record. Extreme temperature values for October ranged from a high of 90 degrees F at Browns Valley (Big Stone County) and Crookston (Polk County) on the 5th, to a low of 13 degrees F at Brimson (St. Louis County) on the 21st. For many locations, record or near-record maximum temperatures were reported during the first nine days of the month. The Twin Cities experienced eight consecutive days of 80 degrees or more during this interval, tying a long-standing record.
Where we stand now:
Significant rainfall shortfalls have been reported across Minnesota over the past three and one-half months. Precipitation totals for the past fourteen weeks are less than three inches in many southern Minnesota counties, a negative departure from the long-term fourteen-week average of four to eight inches. When compared with the same fourteen-week period in the historical database, the 2011 precipitation totals rank among the lowest on record.
The U. S. Drought Monitor, released on October 27, depicts nearly every Minnesota county as experiencing some level of drought. Portions of Koochiching, St. Louis, Lake, and Cook counties are said to be undergoing Severe Drought or Moderate Drought. Stream flow and lake levels in those areas are very low due to the ongoing impact of precipitation deficits accrued during the 2010 growing season and spotty rainfall this season. The Drought Monitor places a large portion of southern Minnesota in the Severe Drought or Moderate Drought categories. Late-summer and autumn precipitation has been minimal in the southern one-third of 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.
The U.S. Geological Survey reports that stream discharge values are very low in many northeast and north central Minnesota watersheds. Stream flow values rank below the 10th percentile for this time of year for a number of rivers in the northern tier of Minnesota counties. Stream flow measurements are also historically low for a few south central Minnesota watersheds. For the Red River and some of its tributaries, river flow is high when compared with historical data for the date, the lingering impact of a wet autumn 2010 and spring 2011.
The Lake Superior water level is near its elevation of a year ago, but down 12 inches from the long-term seasonal average. The water level on White Bear Lake (Ramsey/Washington county border) remains quite low. The White Bear Lake elevation is up by roughly one foot after reaching an all-time record low level mark in November 2010. Lake levels in far northern Minnesota are very low when compared with historical averages for this time of year, especially lakes along the Canadian border.
As of October 30, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 24% Very Short, 43% Short, 33% Adequate, and 0% Surplus. Topsoil moisture steadily declined through the late summer and autumn, especially in southern Minnesota. Dry soils have made autumn tillage difficult in many areas, and have heightened concerns about the soil moisture profile for next growing season.
The potential for wildfires is currently rated by DNR Forestry as High in northwest Minnesota, Low in northeast Minnesota, and Moderate in all other areas.
The November precipitation outlook offers an equal likelihood of below-normal, near-normal, or above-normal conditions throughout the state. November precipitation normals range from around one inch in western Minnesota to over two inches in eastern sections of the state. The average date of the first enduring snow cover ranges from the first week of November in northeastern Minnesota to the final week of November in south central counties.
The November temperature outlook tilts towards above-normal conditions across Minnesota. Normal November high temperatures are in the mid-40s to upper 40s to start the month, dropping to the mid-20s to near 30 by month's end. Normal lows are in the upper 20s early in the month, falling into the mid-teens by late November.
The 90-day precipitation outlook for November through January tilts towards above-normal conditions in Minnesota, especially in northwestern counties. The November through January temperature projection offers an equal likelihood 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 are part of the National Weather Service's Advanced Hydrologic Prediction Service (AHPS).