HydroClim Minnesota - May 2008
A monthly electronic newsletter summarizing Minnesota's 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 happened in April:
- April 2008 precipitation totals were above historical averages across nearly all of Minnesota. With the exception of far northwestern Minnesota, most communities reported significant rain or snowfall totals in April. Precipitation totals in most northeast, east central, and southeastern Minnesota counties topped five inches for the month. Total April precipitation in some southeastern Minnesota locales exceeded seven inches. In a few cases, the monthly precipitation totals were record setting. In west central, north central, and northeastern Minnesota counties, much of the precipitation came as snow. Numerous communities in these areas received over 30 inches of snow for the month, shattering April monthly total snowfall records in many places.
[see: Seasonal Precipitation Maps | April 2008 Climate Summary Table | National Weather Service April Snowfall Summary]
April 2008 produced four major snow events, prolonging a long winter season. Heavy snow, and in some cases blizzard conditions, created treacherous travel and delayed the onset of spring.
[see: April 25-26 Snowstorm and Blizzard | Blizzard of April 10-11 | April 5-7 Heavy Snow | March 31 - April 1 Snow and Rain]
Maintaining a multi-month trend, monthly mean temperatures for April 2008 were below historical averages. April temperatures ranged from two to four degrees below normal across Minnesota. Extreme values for April ranged from a high of 79 degrees on the 23rd at a handful of locations across Minnesota, to a low of 4 degrees at Embarrass (St. Louis County) on the 15th.
[see: April 2008 Climate Summary Table]
Where we stand now:
- The U. S. Drought Monitor, released on May 1, places a small area of west central Minnesota, along with portions of northwestern Minnesota, in the "Abnormally Dry" category. This is an acknowledgement of lingering precipitation deficits from the 2007 growing season. All other Minnesota locales are deemed to be free of drought conditions. The U. S. Drought Monitor index is a blend of science and subjectivity where intensity categories are based on several indicators.
[see: U.S. Drought Monitor]
- The U.S. Geological Survey reports that stream discharge values are above the 75th percentile for the date across most of Minnesota. Along some river stretches, stream flow exceeds the 90th percentile for this time of the year. In spite of the high flows, flooding has not been a major concern thus far this spring.
[see: USGS Streamflow | DNR Streamflow]
- The Lake Superior water level is up 10 inches from last year at this time. Although the Lake Superior water level is now well above the all-time seasonal low, it remains below the long-term average.
[see: Corps of Engineers Great Lakes Water Levels]
- The Minnesota Agricultural Statistics Service reports that as of May 2, topsoil moisture was 1% "Short", 67% "Adequate", and 32% "Surplus". Wet soils and cool temperatures have significantly delayed land preparation and the planting of crops. Field working progress is the slowest since the spring of 1996.
[see: Ag. Statistics Service Crop Progress and Condition]
- Frost has left the soil in most Minnesota locations. However, in a few northwestern Minnesota locations, a lens of frozen soil remains approximate two feel beneath the surface. On average, the soil profile thaws by late March to early April in the south, early April to mid-April in the north. The soil thaws from both the top and the bottom, leaving a layer of frozen soil to be the last to climb above freezing.
[see: National Weather Service River Forecast Center | U of M Climate Observatory | MnDOT Road Frost Depths]
Larger, deeper lakes in the northern one-third of Minnesota remain partially or completely ice covered. Throughout the spring, lake ice-out has lagged behind historical averages by one to two weeks. In most locales, it has been the latest lake ice-out since 1996.
[see: Lake Ice-out Status]
The potential for wildfires is rated by DNR Forestry as "high" in northwestern Minnesota. Fire danger is considered "moderate" throughout most of the northern half of Minnesota. Elsewhere, fire danger is rated as "low". Fire danger 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.
[see: Fire Danger Rating Map]
- The May precipitation outlook tilts significantly towards above-normal conditions across the state. May precipitation normals range from just over two inches in northwestern Minnesota to just less than four inches in southeastern counties. The historical probability of measurable precipitation for any given day in May ranges from 25 percent in the northwest to near 40 percent in the southeast.
[see: Climate Prediction Center 30-day Outlook | May Precipitation Normal Map]
- The May temperature outlook offers a strong tendency towards below-normal conditions across Minnesota. Normal May high temperatures are in the low to mid-60's early in the month, rising to the low to mid-70's at month's end. Normal May low temperatures are in the mid-30's to near 40 to start the month and climb to the mid-40's to low 50's as the month ends.
[see: Climate Prediction Center 30-day Outlook | May Temperature Normal Map]
- The 90-day precipitation outlook for May through July indicates no significant tendencies away from climatological probabilities across Minnesota. The May through July temperature projection offers equal chances of above, near, or below average conditions.
[see: Climate Prediction Center 90-day Outlook]
- 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 are part of the National Weather Service's Advanced Hydrologic Prediction Service (AHPS).
[see: National Weather Service River Forecast Center]
From the author:
Notes from around the state:
Upcoming dates of note:
- May 15: National Weather Service releases 30/90 day temperature and precipitation outlooks
Web sites featured in this edition:
- http://climate.umn.edu - Minnesota Climatology Working Group, Minnesota DNR Waters and U of M Dept. of Soil, Water, and Climate
- http://www.crh.noaa.gov/fgf - Forecast Office, National Weather Service - Grand Forks, ND
- http://www.drought.unl.edu - National Drought Mitigation Center
- http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey
- http://mndnr.gov/waters - Minnesota Department of Natural Resources, Division of Waters
- http://www.lre.usace.army.mil - Detroit District, US Army Corps of Engineers
- http://www.nass.usda.gov - USDA, National Agricultural Statistics Service
- http://www.crh.noaa.gov/ncrfc - North Central River Forecast Center, National Weather Service
- http://www.mrr.dot.state.mn.us - Minnesota Department of Transportation, Office of Materials
- http://mndnr.gov/forestry - Minnesota Department of Natural Resources, Division of Forestry
- http://www.cpc.ncep.noaa.gov - Climate Prediction Center, National Weather Service
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