|HydroClim Minnesota - November 2004
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
- October 2004 precipitation totals were one to three inches above normal across much of the northern two thirds of Minnesota. In the southern one third of the state, precipitation was near to slightly below normal. Although some locations in far northern counties reported snow earlier in the month, there is presently no snow cover anywhere in Minnesota.
- one of the most significant precipitation events of October occurred on the 28th when a narrow band of extremely heavy rain bisected the state. Two or more inches of rain was reported in many areas within a 50 mile wide stripe centered along a line from Madison in Lac Qui Parle county to Pine City in Pine county. A narrow streak of five or more inches of rain drenched southeastern Chippewa and southwestern Kandiyohi counties.
- October monthly mean temperatures were near to somewhat above normal. The temperature extremes for October ranged from 81 degrees at Moorhead, Grand Rapids, and Milan on the 6th, to 18 degrees in Embarrass on the 14th. Southern Minnesota communities experienced "retro-summer" on October 29 when dew point temperatures climbed into the upper 60's. The maximum dew point temperature in the Twin Cities reached 66 degrees. In the modern Twin Cities record, the dew point temperature had never before exceeded 64 degrees that late in the calendar year. Dramatic shifts in weather regimes are common in Minnesota. October 2004 offered a classic example of this fact. Solar radiation data gathered on the St. Paul Campus of the University of Minnesota indicated that the first half of October was among the sunniest on record, whereas the second half of the month was the cloudiest late October in the 40-year record.
WHERE WE STAND NOW
- as Minnesota enters the winter season, much of the landscape features saturated soils and filled surface water systems. 2004 warm season (April through October) precipitation totals were well above historical averages in many Minnesota communities. Two extraordinarily wet months, May and September, bolstered the seven-month totals. Precipitation totals for April through October 2004 exceeded historical averages by four or more inches across large sections of Minnesota. When compared with other April through October periods in the historical database, 2004 warm season rainfall totals ranked above the 95th percentile in many sections of southern, central, west central, and northwestern Minnesota. The wet weather was not universally distributed across the state during the warm season. Precipitation totals for the April through October time frame fell short of normal by 20 or more percent in St. Louis, Lake, and Cook counties.
- as of October 26, the National Drought Mitigation Center (NDMC) - U. S. Drought Monitor indicated that all of the state of Minnesota is free of 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.
- the Minnesota Agricultural Statistics Service reports that as of October 29, the state's topsoil moisture was 0% very short, 3% short, 67% adequate, and 30% surplus.
- U.S. Geological Survey stream gauging efforts indicate that stream discharge values are at all-time high 7-day average flows for the date at most of their monitoring locations in the Red River basin. Some minor flooding was reported in these areas. Stream discharge in the majority of Minnesota's rivers ranks above the 75th percentile for the date. Stream discharge is near the historical average only in sections of east central and northeastern Minnesota.
- the potential for wildfires is rated by DNR Forestry as "low" across Minnesota.
- the November precipitation outlook from the Climate Prediction Center indicates a strong tendency towards below normal conditions for all of Minnesota. November precipitation normals range from around one inch in western Minnesota to over two inches in eastern sections of the state. The average date of the first enduring snow cover ranges from the first week of November in northeastern Minnesota, to the final week of November in south central counties.
- the November temperature outlook shows no significant tendencies away from climatological probabilities. Normal November high temperatures are in the mid-40's to upper 40's to start the month, dropping to the mid-20's to upper 20's by month's end. Normal lows are in the upper 20's early in the month, falling into the mid-teens by late November.
- the 90-day precipitation outlook for November through January indicates no significant tendencies away from climatological probabilities across Minnesota. The November through January temperature outlook also indicates no significant tendencies away from climatological probabilities.
- the National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. A hydrologic model is initialized using current conditions of stream flow and soil moisture across a basin. The model is allowed to run into the future with multiple scenarios using many 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
- from Terry Lejcher, DNR Hydrologist - Fergus FallsUPCOMING DATES OF NOTE
As noted in the October issue of HydroClim, we had a very wet September. At Swan Lake, 5 miles south of Fergus Falls, I recorded 8.95 inches for the month. Several observers in the local area that I trust, reported 11-12 inches for the month. Our annual average total is about 23.5 inches. On Fri. Oct. 22, I recorded 2.34 inches of rain in a 12 hour period. There were several similar reports and a few up to 3.2 inches. What really caught my attention though was the way the depressions and wetlands filled with water from this late October rainfall. We had a very high runoff event. There is water on the side of the hills in the tractor wheel tracks; water in the ditches along the road and sitting every place there is a depression. I have looked at the long range forecast and am concerned to see the prediction is for above normal temps and equal chance of normal moisture. Flow in the Otter Tail River with about 24% storage in the watershed is about 900 cfs; the median flow for this time of year based on 73 years of record is about 205 cfs. It is worth remembering that even with normal moisture during the winter, high antecedent moisture has produced some noteworthy floods in the valley, particularity in Breckenridge. After 2 dry winters, I anticipate a busy late March and early to mid April. I am hopeful the Otter Tail River Diversion will be functional if need be.
* from the author ... in response to Terry's note, the Corps of Engineers reports that the Otter Tail River Diversion will be functional this fall. They have concerns that a flood event may cause erosion on portions of the project that do not have well-established cover, but do not think this will degrade the hydraulic capability of the diversion.
- November 18, Climate Prediction Center releases 30/90 day temperature and precipitation outlooksWEB SITES FEATURED IN THIS EDITION
http://climate.umn.edu - Minnesota Climatology Working Group
http://www.drought.unl.edu/ - National Drought Mitigation Center
http://www.nass.usda.gov/mn/ - Minnesota Agricultural Statistics Service
- U.S. Geological Survey, Minnesota
- Minnesota Department of Natural Resources - 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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