|HydroClim Minnesota - May 2003
A monthly electronic newsletter summarizing Minnesota climate conditions and the
resulting impact on water resources.
Distributed on the Wednesday following the first Monday of each month.
State Climatology Office - DNR Waters
WHAT HAS HAPPENED
- precipitation amounts in April 2003 varied widely across Minnesota. Precipitation fell short of normal by one half inch to one inch across much of the southern one third of the state. Most counties in the northern one third of Minnesota reported somewhat below average precipitation totals as well. A swath of April wetness dissected the central one third of the state. A small corner of southwestern Minnesota also received abundant rain. In central Minnesota and far southwestern Minnesota, April precipitation totals exceeded the historical average by more than one inch. Pipestone, in southwestern Minnesota received over seven inches of rain in April.WHERE WE STAND NOW
- two significant precipitation events of note occurred in April 2003. An April 7 storm deposited more than eight inches of snow on the far southern tier of Minnesota counties. On April 15-17, a slow moving storm moving through the Midwest brought substantial rain to much of the southern two thirds of Minnesota. Rainfall totals exceeding one inch were common during this event, and some locations reported rainfall totals in excess of two inches.
- April temperatures were near to somewhat above normal across Minnesota. As is typical for April, air temperatures varied a great deal from week to week, and from place to place. On April 6, some northeastern Minnesota communities awoke to below-zero temperatures. In contrast, temperatures in mid-April topped 90 degrees in west central Minnesota. The warm temperatures were accompanied by extremely low relative humidity. The combination of heat and low humidity led to an explosive wildfire situation, and resulted in many grass fires. Several Minnesota communities set new all-time maximum temperature records on April 13, 14 and 15.
- a map depicting growing season precipitation totals to date (April 1 - May 5) offers a mosaic of differing conditions across Minnesota. Precipitation totals in far southwestern Minnesota and much of central Minnesota are above normal for the season, and rank above the 85th percentile. Growing season precipitation totals for much of northern Minnesota, and sections of south central and southwestern Minnesota, are below the historical average, and in some cases rank below the 30th percentile.
- surface water levels in some northern Minnesota counties are well below historical values. This can be attributed to precipitation deficits that have accrued over a 6-month period across most of Minnesota, and a 16-month period of dryness in north central and northeastern Minnesota, as well as scattered areas in the south. The shorter of Minnesota's dry spells commenced in mid-October 2002. The period November 2002 through March 2003 was among the driest five-month periods in Minnesota's climate history. Five-month precipitation totals were under two inches for large areas of Minnesota, and under four inches for almost the entire state. Mid-April rains in excess of two inches helped to ease moisture deficits across much of the southern two thirds of Minnesota. However, many areas in far northern Minnesota failed to receive substantial April rain. Longer term precipitation deficits have gripped north central and northeastern Minnesota counties, as well as scattered areas in the south, since early 2002. Precipitation shortfalls during this 16-month period are greater than four inches in some counties. Eight inch deficits are found across northeastern Minnesota.
- as of April 29, the National Drought Mitigation Center - U. S. Drought Monitor indicates that north central and northeastern Minnesota is judged to be in the "D2 - Drought Severe" category. Most of the remainder of the northern two thirds of Minnesota is placed in the "D1 - Drought Moderate" or the "D0 - Abnormally Dry" classification. The NDMC index is a blend of science and subjectivity where intensity categories are based on six key indicators and numerous supplementary indicators.
- the Minnesota Agricultural Statistics Service reports on May 4 that the state's topsoil moisture was 4% surplus, 78% adequate, 15% short, and 3% very short. Ground preparation and spring planting operations are ahead of historical averages.
- the U.S. Geological Survey indicates that stream discharge values for nearly one half of Minnesota's rivers rank below the 25th percentile for the date. Low stream flows are most common in north central and northeastern portions of Minnesota. Stream discharge rates in some of these areas rank below the 10th percentile. Stream flows in the southern one half of the state are near historical medians for the date.
- virtually all of Minnesota's lakes are now free of ice. A handful of deeper lakes in the far northeastern tip of Minnesota remain ice covered. 2003 ice out dates were generally two to six days earlier than average in the southern two thirds of the state, near average in the northern one third of Minnesota.
- water levels on many Minnesota lakes have dropped considerably from last summer's very high values. Water levels on lakes with significant connections to river systems are below average for the date. For many lakes located in land-locked basins, water levels are near average this spring.
- the potential for wildfires is rated by DNR Forestry as high to very high in portions of east central, north central, and northeastern Minnesota. The fire danger is rated as moderate in the remaining areas of the northern two thirds of Minnesota. The fire danger is considered low in the southern one third of the state.
- the May precipitation outlook from the Climate Prediction Center shows no significant tendencies away from climatological probabilities. May precipitation normals range from two and one half inches in northwestern Minnesota to around four inches in southeastern counties.
- the May temperature outlook also indicates no significant tendencies away from climatological probabilities. Normal May high temperatures are near 60 early in the month, rising to the low to mid-70's at month's end. Normal May lows are near 40 to start the month and climb to around 50 as the month ends.
- the 90-day precipitation outlook for May through July shows no significant tendencies away from climatological probabilities. The May though July temperature outlook tilts towards above normal conditions.
- the National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and upper Mississippi River basins. A hydrologic model is initialized using the current conditions of stream flow and soil moisture across a basin. The model is allowed to run into the future with multiple scenarios using more than 30 years of historical climatological data. The climatological data are weighted by 90-day climate outlooks for temperature and precipitation trends. Model output offers a complete range of probabilistic values of stream stage and discharge for numerous forecast points. The product provides a risk assessment tool which can be used in long-range planning decisions involving flooding or low flow concerns. These products are part of the National Weather Service's Advanced Hydrologic Prediction Service (AHPS) and are produced near the middle of each month.
FROM THE AUTHOR
NOTES FROM AROUND THE STATE
- noneUPCOMING DATES OF NOTE
- May 15, Climate Prediction Center releases 30/90 day temperature and precipitation outlooksWEB SITES FEATURED IN THIS EDITION
- Minnesota Climatology Working Group
http://www.drought.unl.edu/ - National Drought Mitigation Center
http://mrcc.sws.uiuc.edu/ - Midwestern Regional Climate Center
http://swroc.coafes.umn.edu/ - University of Minnesota Southwest Research and Outreach Center, Lamberton
- U.S. Geological Survey, Minnesota
- Minnesota DNR Division of Waters
- Minnesota DNR Division of Forestry
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://www.crh.noaa.gov/ahps - National Weather Service, Central Region Headquarters
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