HydroClim Minnesota - February 2002

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 2/6/02


- January precipitation was very light across Minnesota. Precipitation totals were near or below one quarter of an inch for all but southeastern Minnesota. Most southeastern Minnesota communities reported precipitation totals of around two thirds of an inch. Precipitation fell short of the historical norm by approximately one half inch over most of Minnesota.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )
- keeping with a pattern established in November, temperatures in January finished 9 to 14 degrees above the historical mean across the state. Many Minnesota communities set all-time maximum temperature records on January 8, January 9, and January 25. Some communities in south central and southwestern Minnesota reported temperatures in the mid to upper 50's on January 8. The temperature at the Twin Cities International Airport fell below zero for the first time this winter on January 18. This set a record for the longest stretch into winter without a below-zero temperature. According to preliminary statistics from the Midwestern Regional Climate Center, the November through January period was the warmest such period for the State of Minnesota by more than two degrees.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp , http://climate.umn.edu/doc/journal/warm020108.htm , http://climate.umn.edu/doc/journal/warm020110.htm , http://climate.umn.edu/doc/journal/warmnovjan.htm )


- snow depths are less than four inches across the southern two thirds of the state, as well as far northwestern Minnesota. Snow cover left by last week's winter storm affecting south central and southeastern Minnesota will erode due to this week's seasonally mild weather. Snow cover in north central and northeastern Minnesota is variable, ranging from three to ten inches. Many locations adjacent to the north shore of Lake Superior report snow depths of less than three inches. The January 31 snow depth ranking map shows that values over nearly all of Minnesota ranked below the 20th percentile for the date. Snow depths across large regions of the state were below the fifth percentile, and a significant number of Minnesota communities were at the first percentile. For an area ranking in the first percentile, it means that snow depths were at or below the all-time minimum value for the date.
(see: http://climate.umn.edu/doc/snowmap.htm )
- heavy late November rainfall and snowfall brought relief to areas affected by precipitation deficits established during the later part of the 2001 growing season. Because the considerable November precipitation fell before soil freeze-up, the soil moisture profile was amply recharged in most areas. There are reports from western Minnesota of dry soil near the surface due to the limited winter snowfall.
- as of January 29, the National Drought Mitigation Center designates most of the southeastern one quarter of Minnesota and portions of northwestern Minnesota as "Abnormally Dry". The remainder of the state is free of any drought designation. 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 February 2 Palmer Drought Severity Index (PDSI) from the Climate Prediction Center places south central, central, and east central Minnesota counties in the "Moderate Drought" category. Other areas are categorized as "Near Normal". The Palmer Drought Severity Index is used for assessing long-term meteorological conditions.
(see: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif )
- the U.S. Geological Survey indicates that discharge values for all Minnesota streams (where winter reporting is possible) are in the normal to above normal categories for the date.
(see: http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd )
- soil frost depth data gathered on January 29 by the U.S. Army Corps of Engineers and the University of Minnesota indicate that frost depths, as measured under a sod surface, were 4 to 10 inches in the south, 12 to 18 inches in the west and north. Soil frost penetration depths would typically be twice that of this year's levels.
(see: http://www.mvp-wc.usace.army.mil/projects/reservoirs.shtml )


- the February precipitation outlook from the Climate Prediction Center shows no significant tendencies away from climatological probabilities. Historically, February is Minnesota's driest month with precipitation normals ranging from less than one half inch in northwestern Minnesota to near three quarters of an inch in eastern sections of the state. The median snow cover at the end of February ranges from under 5 inches in the southwest Minnesota, to over 18 inches on the ground in northeastern Minnesota (greater than 30 inches in the Lake Superior highlands). The February temperature outlook also shows no significant tendencies away from climatological probabilities. Normal February high temperatures climb from the mid to upper teens early in the month to the mid to upper 20's by month's end. Normal February lows begin the month from near minus 10 degrees in the far north, the single digits above zero in southern Minnesota. By late February, normal lows are in the low single digits above zero in the far north, and near 10 degrees in the south.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/seasonal_forecast.html   )
- the 90-day precipitation outlook for February through April shows no significant tendencies away from climatological probabilities. The February though April temperature outlook also shows no significant tendencies away from climatological probabilities.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/seasonal_forecast.html )
- 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 climatological data. The climatological data are weighted by the 90 day outlooks for temperature and precipitation trends. The model output offers a complete range of probabilistic values of stream stage and discharge for numerous forecast points. The product offers 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 will be produced near the middle of each month.
(see: http://www.crh.noaa.gov/ahps/index.html )


- staff from various state and federal agencies gathered at this year's annual interagency spring flood coordination meeting on January 29. To state the obvious, spring flood potential was declared be quite low at this time. It was interesting to note that this meeting was very well attended in spite of the lack of pressing flooding concerns. Minnesota's water resource professionals recognize the need for interagency communication and cooperation when dealing with flood situations. These individuals utilize opportunities such the annual meeting to build relationships, and to share concerns and ideas. We Minnesotans are most fortunate to have them overseeing the protection of lives and property against the threat of flooding. In keeping with that theme ... it was announced at this year's meeting that Gary McDevitt, hydrologist at the National Weather Service Forecast Office in Chanhassen, has recently won the prestigious "Isaac M. Cline" national award for hydrology. Gary was recognized for his outstanding service to the citizens of Minnesota during the 2001 spring flood episode.
- in the discussions above, I point out that two of the national drought monitoring indices depict portions of Minnesota in developing or ongoing drought categories. The indices reflect the scarcity of winter snowfall and the extraordinarily warm winter temperatures, and attempt to quantify the present climatological anomaly. Precipitation deficits that occur during the Minnesota winter have a profound affect on the winter recreation industry. However, from a water resource standpoint we must recall that on average, the total water volume deposited by winter precipitation is small when compared to annual precipitation. Therefore, below normal winter precipitation has a much smaller impact on water resources than deficits established during the growing season.


- beginning this spring, the National Weather Service will issue probabilistic river stage and discharge outlooks for the Mississippi River above Red Wing. Previously, probabilistic outlooks were available only for the Minnesota and Red River basins.


- February 14, Climate Prediction Center releases 30/90 day temperature and precipitation outlooks
- February 14-21, Probabilistic Flood Outlooks issued by National Weather Service
- February 20, Interagency Flood Planning Coordination Meeting - National Weather Service, Chanhassen
- February 22, Narrative Flood Outlook issued by National Weather Service


http://climate.umn.edu - Minnesota Climatology Working Group
http://enso.unl.edu/ndmc/ - National Drought Mitigation Center
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey, Minnesota
http://www.mvp-wc.usace.army.mil/projects/reservoirs.shtml - U.S. Army Corps of Engineers, St. Paul District
http://www.crh.noaa.gov/ahps/index.html - National Weather Service - Central Region Headquarters


- Dan Luna, Hydrologist in Charge, National Weather Service - North Central River Forecast Center

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