|HydroClim Minnesota - December 2000
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
- November precipitation was well above normal across most of Minnesota. November precipitation totals averaged around three and one half inches statewide, with many locations topping four inches. Precipitation in many Minnesota counties exceeded the long-term November average by more than two inches.
- early November precipitation was extraordinarily heavy. During the first week of the month, all of Minnesota received more than one inch of rain, and most of the northern two thirds of Minnesota received more than two inches. These totals exceeded the historical averages for the entire month of November. Many single-day precipitation records were set on November 6. Minor flooding was reported along many of the tributaries of the Red River in early to mid November.
- November temperatures were two to five degrees below the historical average in west central and southwestern Minnesota, and one to three degrees below average in the remainder of the southern two thirds of the state. Locations in the northern one third of Minnesota were one to three degrees above normal. Some minimum temperature records were set on November 20, 21, and 22.
- while not related directly to hydrology, a notable meteorological event occurred in early November. For only the third time in recorded history, Minnesota experienced a November tornado. On November 1, a tornado caused damage to power lines and outbuildings in Kandiyohi county.
WHERE WE STAND NOW
- the heavy early November rainfall brought relief to parched water resources affected by the significant precipitation deficits found in southwestern, central, east central, and far northeastern Minnesota over the last 15 months. Falling before soil freeze-up, the rains helped to replenish dehydrated topsoil in these areas. Additionally, surface hydrology levels have climbed in response to the heavy precipitation. Nonetheless, the accumulated long-term precipitation shortfalls were significant in these areas, and precipitation remains three to six inches below normal for the year. Unfortunately, the torrential early November precipitation also fell upon northwestern Minnesota, a region already wet from heavy late summer and autumn rains. In many northwestern Minnesota counties, annual precipitation is far above average and streams in the area are at or above bank full.
- mid and late November snow events blanketed many Minnesota communities with a lasting snow cover. In spite of some above freezing temperatures during last week of the month, most of Minnesota has at least two inches of snow on the ground as of this writing.)
- as of their November 30 release, the National Drought Mitigation Center - "U.S. Drought Monitor" shows Minnesota to be free of any 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.
- the December 2 Palmer Drought Severity Index (PDSI) depicts most of Minnesota in the "Near Normal" category. Counties in northwestern and north central Minnesota are categorized as experiencing an "Unusual Moist Spell". The Palmer Drought Severity Index is used for assessing long-term meteorological conditions.
- in their final release of the season, the Minnesota Agricultural Statistics Service reported that topsoil moisture conditions across the state were rated 5% very short, 22% short, 60% adequate, and 13% surplus as of Friday, November 3. Thanks to the heavy early November rain, the amount of acreage categorized as short or very short decreased dramatically when compared to early October. Given that Minnesota soils are now frozen, the condition of the soil moisture profile will change very little until late winter or early spring.
- stream discharge values are difficult to determine during the frozen water season. However, for gauging locations that provide winter data, the U.S. Geological Survey indicates that most streams in the Red River basin are above the 90th percentile when compared to historical values for the date. Stream flows in the remainder of the state are near average for the date.
- cold temperatures in early December led to rapid lake ice development. Ice thickness on many Minnesota lakes is five to seven inches, and thickening rapidly. However, ice thickness often varies dramatically from lake to lake, or even bay to bay.
- the 30-day outlook from the Climate Prediction Center calls for near normal December precipitation across all of Minnesota. Normal December precipitation ranges from just over one half inch in western Minnesota, to one and one quarter inches in the northeast. The December temperature outlook is also for near normal conditions statewide. Normal December high temperatures fall from the upper 20's early in the month to around 20 by month's end. Normal December lows drop from the low teens early in the month to around zero by late December.
- the 90-day outlook for December through February indicates near normal precipitation statewide. The December through February temperature outlook also calls for near normal conditions throughout Minnesota.
FROM THE AUTHOR
- in spite of the fact that historical precipitation averages drop off significantly during November, central and east central Minnesota overcame the probabilities and received relief in the form of very heavy rains. The rains came before the first significant cold spell of the winter season, thus soils were unfrozen and receptive to recharge. While the rains have done much to alleviate hydrological imbalances in these areas, adequate spring snow-melt runoff and early spring rains are still necessary to fully rejuvenate wetland, lake, and stream levels in 2001.
Conversely, soil moisture and surface water systems are at unusually high levels in northwestern Minnesota, and above average spring snow-melt runoff or above average early spring rains would pose problems in the spring of 2001.
NOTES FROM AROUND THE STATE
UPCOMING DATES OF NOTE
- December 14, Climate Prediction Center releases 30/90 day outlooks
WEB SITES FEATURED IN THIS EDITION
http://climate.umn.edu - Minnesota Climatology Working Group
Contributions of information and suggestions are welcome!