|HydroClim Minnesota - April 2006
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
compiled 4/4/06 (early distribution by one day)
WHAT HAS HAPPENED
- precipitation totals for March 2006 were above average in the northern one third of Minnesota and in the southern one third of Minnesota. Precipitation topped historical averages by one half inch to one and one half inches in these areas. In the central one third of the state precipitation generally fell short of average by one half inch to one inch.
- two of the larger snow producers of March occurred during the third week of the month. On March 12 and 13, 6 to 12 inches of moisture-laden snow fell upon southern and east central Minnesota. A location near Hastings reported 19 inches of snow during this event. Just two days later (March 15-16), another winter storm dropped four to eight inches of snow over many of these same areas.
- moderate to heavy rain fell on March 30 and 31 across much of Minnesota. Rainfall totals were generally from one half inch to one inch. Daily rainfall records were set in some communities on the 31st.
- March 2006 monthly mean temperatures were somewhat above average in the northern two thirds of Minnesota, near average in the southern one third of the state. The temperature extremes for March ranged from 66 degrees at Canby (Yellow Medicine county) on the 30th, to -15 degrees at Hallock (Kittson county) on the 15th and -15 degrees at Embarrass (St. Louis county) on the 18th.
WHERE WE STAND NOW
- as of this writing (April 4), moderate to major river flooding is underway along the Red River and some of its tributaries. Also, a few locations in the Mississippi and Minnesota river basins are experiencing minor flooding. The flooding in the Red River basin is the result of the rapid melting of a high water content snow pack, exacerbated by moderate to heavy rainfall that fell on March 30 and 31.
- snow cover remains only in Minnesota's northernmost tier of counties. In these areas, snow depths are generally less than four inches. Some wooded areas along the Lake Superior highlands still report six or more inches of snow on the ground.
- as of March 28, the National Drought Mitigation Center (NDMC) - U. S. Drought Monitor indicated that all Minnesota counties are free of drought designations. The NDMC index is a blend of science and subjectivity where intensity categories are based on six key indicators and numerous supplementary indicators.
- soil frost has rapidly left the ground in most locales. Soil frost thaws from both the top and bottom, leaving a lens of ice between one and two feet below the surface. This lens of ice is the last to thaw; typically in early April in the south, early to mid-April in the north.
(see: http://climate.umn.edu/doc/observatory.htm , http://www.mvp-wc.usace.army.mil/projects/reservoirs.shtml
- many of the larger lakes in the southern one quarter of Minnesota are now free of ice. Thus far this spring, lake ice-out dates have been close to average. Historically, average lake ice-out occurs during the first week of April in the southern tier of Minnesota counties; near the end of the second week of April in the Twin Cities metropolitan area; towards the end of the third week of April for Brainerd, Alexandria, and Detroit Lakes area lakes; and during the final week of April in far northern Minnesota.
- the U.S. Geological Survey reports that stream discharge values for three quarters of Minnesota's rivers and streams are above the 75th percentile for the date. Stream flows in the Red River basin are above the 90th percentile for the date, with some locations reporting new record high values for early April.
- the potential for wildfires is rated by DNR Forestry as "low" across Minnesota. These conditions can change rapidly in response to warm, sunny, and windy weather. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
- moderate to major spring flooding along the Red River and many of its tributaries will continue through the weekend in areas north of Fargo/Moorhead. South of Fargo/Moorhead, river levels are beginning to recede. Additional rain on Thursday is not expected to raise the projected crest levels, but will sustain the crest for a longer period of time. Elsewhere in Minnesota, minor flooding will continue for a few days in some locations within the Minnesota and Mississippi river basins.
- the April precipitation outlook from the Climate Prediction Center indicates a strong tendency towards above normal conditions across Minnesota. April precipitation normals range from one and one half inches in northwestern Minnesota to around three inches in southeastern counties. The historical probability of measurable precipitation for any given day in April ranges from 20 percent in the far northwest to 35 percent in the southeast.
- the April temperature outlook from the Climate Prediction Center indicates no significant tendencies away from climatological probabilities across Minnesota. Normal April high temperatures are in the mid to upper 40's early in the month, rising to the low 60's by month's end. Early April normal low temperatures are near 20 in the north, near 30 in the south. By month's end, low temperatures average in the mid 30's in the north, near 40 in the south.
- the 90-day precipitation outlook for April through June indicates a tilt towards above normal rainfall across the northern two thirds of Minnesota and no significant tendencies away from climatological probabilities in the southern one third of the state. The April through June temperature outlook depicts an inclination towards below normal temperatures in northwest Minnesota. Elsewhere in Minnesota, the 90-day temperature outlook indicates no significant tendencies away from climatological probabilities.
FROM THE AUTHOR
- an excerpt from Dr. Mark Seeley's March 31 "WeatherTalk" commentary
NOTES FROM AROUND THE STATE
Yet Another Warm Winter.....
Historically in Minnesota the November through March period has been called the "heating season" or the "snow accumulation season." By either name the expectations are cold, snow, and frozen lakes. But recent trends in our Minnesota climate are going away from these expectations. Consider the nine most recent "heating seasons" and the calculated mean temperature over these months, then ranked relative to the distribution of statewide values since 1895, with 1 = coldest, and 112 = warmest.........
Heating Season Mean Temp (F) Ranking (since 1895)
1997-1998 24.2 106th
1998-1999 23.0 104th
1999-2000 26.1 110th
2000-2001 15.8 28th
2001-2002 24.9 109th
2002-2003 19.4 73rd
2003-2004 20.5 87th
2004-2005 21.3 94th
2005-2006 22.9 103rd
(median value is 17.8 F)
Only one heating season, 2000-2001, of the past nine ranks in the cold part of the historical distribution. The eight others rank in the warmest third of the distribution, and five of those rank among the warmest ten since 1895. The persistence of this warm signal is hard to ignore.
- noneUPCOMING DATES OF NOTE
- April 20, Climate Prediction Center releases 30/90 day temperature and precipitation outlooksWEB SITES FEATURED IN THIS EDITION
- Minnesota Climatology Working Group
http://www.dnr.state.mn.us/waters - Minnesota Department of Natural Resources, Division of Waters
http://www.weather.gov/ahps/ - National Weather Service - Advanced Hydrologic Prediction Services (AHPS)
http://www.drought.unl.edu - National Drought Mitigation Center
http://www.mvp-wc.usace.army.mil/ - U.S. Army Corps of Engineers, St. Paul District
http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey
http://www.dnr.state.mn.us/forestry - Minnesota Department of Natural Resources, Division of Forestry
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://climate.umn.edu/weathertalk - Dr. Mark Seeley's WeatherTalk Commentary
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