Drought Situation Report - July 27, 2006

More drought information resources are found at http://climate.umn.edu/doc/journal/dry_summer_2006.htm.

Weekly Precipitation Map

Weather last week:
Rainfall last week (map on right) was plentiful in some areas of south central and southeastern Minnesota. However, the rain was not widespread and did little to alleviate Minnesota's rapidly developing drought conditions in the northern one half of Minnesota. Welcome rain fell on July 19 and was focused primarily on south central and southeastern Minnesota. Martin and Faribault counties were among the drier places in the southern half of the state. The two to four inch rain in these counties on the 19th was beneficial to agricultural interests. Another streak of heavier rain, roughly from Mankato to Rochester, fell upon an area that has been somewhat better off than the rest of southern Minnesota. On July 23 and 24, welcome rains drifted across northeastern Minnesota and dropped over an inch in some areas, temporarily easing fire conditions in the BWCA. Temperatures last week across Minnesota averaged one to three degrees above normal, but the oppressive heat of July 14 and 15 was not repeated.

Weather last few days:
During the evening hours of July 25, moderate to heavy rain fell over sections of northwestern, central, and east central Minnesota. Some rainfall totals on the 25th include 0.68 inch at Fargo/Moorhead, 0.61 inch at Brainerd, and 2.22 inches at Wild River State Park (Chisago county).

Seasonal weather overview:
Dryness has been entrenched in Minnesota for ten weeks. Large-scale, precipitation-producing weather systems have been absent since mid-May. For much of this time, Minnesota has been under the influence of weak northwesterly flow in the upper atmosphere. During the summer, such a weather pattern leads to geographically-isolated and short-lived showers and thunderstorms. The timing of the dry weather has been most unfortunate. The period from late-May into mid-July is historically one of the wettest times of the year. Long-term average rainfall rates during this time interval are around one inch per week. Very dry weather occurring during a time of year when ample rain is typical, led to the rapid onset of drought. The precipitation shortfalls have led to deteriorating crop conditions, low stream flows, and wildfires.

Drought Monitor Map

Drought status:
The latest National Drought Mitigation Center Drought Monitor released Thursday, July 27, places northwestern, central, and east central Minnesota in the Extreme Drought category. The situation transitions to a Severe Drought category surrounding the Extreme Drought polygon. All other Minnesota locations, with the exception of south central and southeast Minnesota, are depicted in the Moderate Drought classification. South central and southeast Minnesota are depicted as Abnormally Dry. Possible impacts for landscapes depicted as experiencing Extreme Drought include: major crop/pasture losses; widespread water shortages or restrictions. Possible impacts for landscapes depicted as experiencing Severe Drought include: crop or pasture losses likely; water shortages common; water restrictions imposed. Possible impacts for landscapes depicted as experiencing Moderate Drought include: some damage to crops, pastures; streams, reservoirs, or wells low, some water shortages developing or imminent; voluntary water-use restrictions requested. The next Drought Monitor will be released on Thursday, August 3. Without significant, wide-spread rain, many areas of Minnesota will either maintain or experience worsening drought conditions. See: 12-Week Drought Progression Animation.

Sector briefs:
Agriculture - The Agricultural Statistics Service reports that topsoil moisture for 75% of Minnesota's landscape is now "Short" or "Very Short". This percentage is nearly the same a week ago with some improvement in south central Minnesota. Minnesota's corn crop is in the midst of its critical reproductive stages. Heat and moisture stress during this period leads to significant yield loss.
Stream flow - Stream flow in one half of Minnesota's rivers and streams falls below the 25th percentile when compared with historical data. Flow conditions in many northern, central, and eastern Minnesota watersheds have dropped below the "Protected Flow" threshold (lowest 10th percentile), leading the Department of Natural Resources to suspend surface water appropriation permits in these areas.
Public water supply - Many Minnesota communities are imposing watering restrictions or outright watering bans.
Wildfire - Wildfire danger is "High" or "Very High" in northern and central Minnesota counties. The Cavity Lake Fire in the BWCA area of the Superior National Forest is reported at 31,850 acres as of July 25.

Ten-week precipitation totals, departure, and ranking:
Rainfall totals over the past ten weeks were less than four inches in many counties and less than three inches across much of northwestern Minnesota. Ten-week rainfall totals deviated negatively from historical averages by more than three inches in most areas. Rainfall deficits exceeded five inches in portions of northwest, central, and southeast Minnesota. When compared with other May 16 to July 24 rainfall totals in the historical database, this year's rainfall totals for the period rank among the lowest on record in some locales. The situation is especially acute in northwest Minnesota where near-record low precipitation totals are common across a multi-county area.

May 16 to July 24 2006 Precipitation Map
May 16 to July 24 2006 Precipitation Departure Map

Ranking maps explained

May 16 to July 24 2006 Precipitation Ranking Map

Previous Drought Situation Report (July 26)
Previous Drought Situation Report (July 21)
Previous Drought Situation Report (July 11)

More drought information resources are found at http://climate.umn.edu/doc/journal/dry_summer_2006.htm.

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URL: http://climate.umn.edu/doc/journal/drought_situation_report_2006_060727.htm
Last modified: July 27, 2006