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: August 1, 2013
What happened in July 2013:
- July rainfall totals were generally below historical averages in most Minnesota counties, except in far northern Minnesota and portions of east central Minnesota where monthly precipitation totals were above average. In some communities, especially in southwestern counties, monthly precipitation totals fell short of long-term averages by two or more inches.
- Two particularly intense rain events occurred during July. In the early morning hours of July 13, continuously redeveloping thunderstorms quickly dropped four or more inches of rain on portions of east central and south central Minnesota. The deluge led to numerous reports of rural and urban flooding. Very heavy rain was also reported in northeast Minnesota on July 18 and 19. Three to five inches of rain led to street flooding in Grand Marais and the temporary closure of Highway 61 in Cook County.
- As was the case in June, average monthly temperatures for July in Minnesota were quite close to historical averages. Extremes for the month ranged from a high of 97 degrees on the 18th at the Minnesota City Dam (Winona County), to a low of 35 degrees at Embarrass (St. Louis County) on the 29th. Warm temperatures during the first three weeks of July accelerated crop development, bringing crop progress nearer to long-term averages after a delayed start to the growing season. Cool temperatures were prevalent during the final week of July. A number of record cold maximum and record cold minimum temperatures were set on July 27.
Where we stand now:
- Season-to-date precipitation totals are highly variable across Minnesota. Spring and early-summer precipitation totals were ample to excessive in southeast Minnesota. And despite recent dryness, seasonal rainfall totals in southeastern counties remain eight or more inches above the historical average. Elsewhere, the seasonal precipitation map offers a fluctuating pattern of values above and below historical normals by one to four inches.
- The U. S. Drought Monitor, released on August 1, places small portions of northwest and north central Minnesota in the Moderate Drought category. The release also places a swath of southwest and central Minnesota in the Abnormally Dry category. Just two percent of Minnesota's landscape is in Moderate Drought, a substantial improvement over early April 2013 when 67 percent of Minnesota was experiencing Extreme Drought or Severe Drought. The expansion of the Abnormally Dry area was due to July rainfall shortfalls of two to four inches. Subsoil moisture reserves and cool late-July weather have alleviated serious drought concerns as of this writing. 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 and the Minnesota DNR report that stream discharge values are near historical medians at most gauging locations with some reports of low stream flow in northwest counties and reports of high stream flows in southeast, west central, and northeast Minnesota.
- Water levels on Minnesota lakes responded upward to heavy spring and early summer precipitation after being very low in late 2012. Lake levels are now generally dropping as is typical in the mid-summer.
- In their July 28 report, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 4% Very Short, 22% Short, 72% Adequate, and 2% Surplus across Minnesota. Subsoil moisture was said to be 2% Very Short and 19% Short. Soil moisture measurements made at University of Minnesota Research and Outreach Centers in mid-July indicated near-average conditions in those southern Minnesota locations.
- The potential for wildfires is currently rated by DNR Forestry as Moderate in a few central Minnesota counties, Low elsewhere across the state.
- The August precipitation outlook indicates equal chances of below-normal, near-normal, or above-normal conditions throughout Minnesota. August precipitation normals range from under three inches in northwest and west central Minnesota to over four and one half inches in southeastern counties.
- The August temperature outlook tilts strongly towards below-normal conditions across Minnesota. Normal August high temperatures are around 80 degrees to start the month, dropping to the mid-70s by month's end. Normal lows are around 60 degrees early in the month, falling to the mid-50s by late August.
- The 90-day precipitation outlook for August through October offers equal chances of below-normal, near-normal, or above-normal conditions everywhere in Minnesota. The August through October temperature projection also calls for 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