- precipitation shortfalls over the period October, 1999 through April, 2000 led to significant deficits in surface hydrology normally benefiting from autumn recharge, spring snow melt runoff, and early spring rains. The situation was most acute in southwestern Minnesota where the dry spell commenced in July, 1999. The extended dry spell manifest itself in lower lake levels, dry wetland complexes, reduced stream flow, and dry soils. For southern Minnesota counties, the dry spell abruptly ended in May. These areas received abundant to excessive precipitation during the month, easing or eliminating the concern for drought. However, the relief was not universally distributed. Precipitation totals for portions of east central, northeastern, and northwestern Minnesota are below normal for the growing season.
(see: http://climate.umn.edu/doc/weekmap.asp)

- precipitation totals for the month of May were generally near average in central and northern Minnesota, and much above average across the southern third of Minnesota. In some areas of southern Minnesota, May precipitation totals exceeded the average by three to five inches. This large positive departure does not include totals from a major rainfall event that ended on June 1. For some southeastern Minnesota communities, rainfall amounts exceeded twelve inches from mid-May to early June. Two very notable precipitation events drenched southern Minnesota in May. The first event occurred May 17-18. Precipitation totals from this storm ranged from two to six inches across a multi-county area, with values exceeding six inches in areas of Freeborn and Mower counties. In many counties, the rain was welcome break in an extended dry spell. The second large southeastern Minnesota rainfall event happened on May 31 and June 1. In this storm, precipitation totals ranged from two to five inches across a multi-county area and the heavy rains hit in the same locales that received two to six inches of rain on May 17-18. Significant urban and rural flooding, and soil erosion were caused by this event.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp, http://climate.umn.edu/doc/journal/flash_floods/ff000518.htm, http://climate.umn.edu/doc/journal/flash_floods/ff000601.htm)

- May temperatures were somewhat above historical averages throughout Minnesota. The month began very warm, with some locations topping 90 degrees during the first week of the month. The temperatures cooled significantly by mid-month and the month's end, but the monthly average still finished above average.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp)

- as of their May 30th release, the National Drought Mitigation Center no longer classifies any Minnesota region in a drought category. Only four weeks ago, southwestern Minnesota was experiencing "Severe Drought", and the remainder of southern Minnesota was listed at the "First Stage Drought" level. Presently, some areas of northwestern and west central Minnesota are currently in the "DO" category ("Abnormally Dry"). The NDMC index is a blend of science and subjectivity where intensity categories are based on six key indicators and numerous supplementary indicators.
(see http://enso.unl.edu/monitor/monitor.html)

- the June 3rd Palmer Drought Index depicts all of Minnesota in the "Near Normal" category with the exception of south central Minnesota, which is labeled as experiencing an "Unusual Moist Spell". The Palmer Drought Index is used for assessing long-term meteorological conditions.
(see http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif)

- the Minnesota Agricultural Statistics Service reports that topsoil moisture conditions across the state were rated 3% very short, 4% short, 74% adequate, and 19% surplus as of Friday, June 2. They report that in the northern part of the Red River Valley, topsoil moisture has become very short. Plant available soil moisture measured at the U. of M. facility in Waseca (Waseca county) exceeds 14 inches in a five foot profile, well above field capacity. Plant available moisture measured at Lamberton (Redwood county) has risen to five and one half inches, a significant rise since May 1. Measurements at both locations are taken at plots planted in corn, soybeans, or a corn/soybean rotation.
(see: http://www.nass.usda.gov/mn/cwmn.htm, http://swroc.coafes.umn.edu/Weather/Charts/Soil/00_soil_water.html)

- current stream discharge values for most Minnesota streams rank between the 25th and 75th percentile for this time of year. According to U.S. Geological Survey reports, some stream flows fall below the 25th percentile in east central, northeastern, and northwestern Minnesota. Conversely, flows rank above the 90th percentile in most southern Minnesota streams. DNR Waters reports that the heavy late May rains in southeastern Minnesota caused what is initially being considered a 50-year flood event on the Root River. The stream gauge on the Root River at Lanesboro was destroyed by the flooding.
(see http://water.usgs.gov/cgi-bin/daily_flow?mn , http://www.dnr.state.mn.us/waters/programs/surwat_section/stream_hydro/productsf.html)

- the 30-day outlook from the Climate Prediction Center calls for near normal June precipitation across Minnesota. Normal June precipitation ranges from three and one half inches in the northwest, to five inches in the southeast. The June temperature outlook tilts towards above normal conditions statewide. Normal high temperatures climb from near 70 in early June to near 80 by the end of the month. Normal June lows are mainly in the 50's.
(see http://www.cpc.ncep.noaa.gov)

- the 90-day outlook for June through August tilts towards below-normal precipitation statewide. The June through August temperature outlook indicates above-normal conditions statewide.
(see http://www.cpc.ncep.noaa.gov)

- one short month ago, this newsletter stated that the "precipitation deficits leave Minnesota's water resources very dependent on adequate spring and summer rains". Demonstrating remarkable capacity for change, Minnesota weather patterns changed abruptly and brought more than "adequate" rains to many critically dry areas. The focus on dryness now shifts from southwestern Minnesota to some areas of east central and northwestern Minnesota. Drought information resources can be found on the State Climatology Office Web site at http://climate.umn.edu/doc/drought_2000.htm .

- with temperatures climbing and plants now actively growing, evapotranspiration is on the increase. Rainfall rates during the summer are often matched or exceeded by evapotranspiration rates and therefore much of the summer rainfall is "consumed" by the evapotranspiration process. Unless rainfall significantly exceeds average, surface and near-surface ground water levels will not rise, but rather they will likely drop.

- in southeastern Minnesota communities where the May rains were excessive, soils remain saturated. The saturated soils, in tandem with the steep terrain of the area, makes these areas particularly vulnerable to flooding in the near term.

UPCOMING DATES OF NOTE:

- June 15, Climate Prediction Center releases 30/90 day outlooks

ACKNOWLEDGEMENTS:

Mike Mueller, DNR Waters Hydrologist - Cambridge
Bob Potocnik, DNR Waters Surface Water Specialist - St. Paul
Dana Dostert, DNR Waters Hydrologist - St. Paul
Dave Ruschy, Department of Soil, Water and Climate - U. of. M
Mark Seeley, Agricultural Meteorologist - U. of M. Extension Service

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