|HydroClim Minnesota - January 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
WHAT HAS HAPPENED
- December precipitation was below historical averages across nearly all of Minnesota. Precipitation totals ranged from one quarter inch to one and one quarter inches. These values fell short of the historical norm by approximately one half inch in most locations. A complex of thunderstorms dropped nearly a half inch of rain on December 5 over far southeastern Minnesota. December thunderstorms are rare, but not unprecedented in Minnesota. Much of Minnesota was rescued from a brown Christmas by a December 22 snow event that deposited two to six inches of snow across much of the state.
- (repeated from last month): heavy late November rainfall and snowfall brought relief to areas affected by precipitation deficits established during the later part of the 2001 growing season. Growing season precipitation totals in southwestern, central, east central Minnesota counties were significantly below normal, and the lack of soil moisture reserves available for the 2002 growing season was a concern. However, because the considerable November precipitation fell before soil freeze-up, the soil moisture profile has been amply recharged. While the soil laid first claim to the November precipitation, water levels in surface hydrology systems such as lakes, rivers, and wetlands rose in response to the rain and snow melt.
- as of January 3, the National Drought Mitigation Center shows Minnesota to be 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 January 5 Palmer Drought Severity Index (PDSI) from the Climate Prediction Center depicts most Minnesota counties in the "near normal" category. East central Minnesota counties are placed in the "Moderate Drought" category. However, I believe this designation to be erroneous. The error may arise from data quality issues that will be repaired in future renditions. 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 all Minnesota streams (where winter reporting is possible) are in the normal to above normal categories for the date. Nearly one half of these stations report stream discharge above the 90th percentile for this time of year.
(see: http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd )
- the mild temperatures of November and December delayed the formation of ice on many large Minnesota lakes until mid-December. While historical lake freeze-up data are sparse, anecdotal reports indicate that lake ice formation dates this season were many weeks later than average, and among the latest ever. This season's "ice-in" dates were similar to those reported in December 1998, when balmy weather was also common during the early winter. While all of Minnesota's lakes are currently ice-covered, ice thickness and integrity are not at typical January conditions.
- the January precipitation outlook from the Climate Prediction Center shows no significant tendencies away from climatological probabilities. January precipitation normals range from one half inch in western Minnesota to near one inch in eastern sections of the state. The median snow cover at the end of January ranges from near 5 inches in the southwest Minnesota, to over 15 inches on the ground in northeastern Minnesota (greater than 24 inches in the Lake Superior highlands). The January temperature outlook also shows no significant tendencies away from climatological probabilities. Normal January high temperatures range the low-teens in the north to near 20 in the south. Normal January lows range from near minus 10 degrees in the far north to the single digits above zero in southern Minnesota.
FROM THE AUTHOR
UPCOMING DATES OF NOTE
- January 17, Climate Prediction Center releases 30/90 day temperature and precipitation outlooks
http://climate.umn.edu - Minnesota Climatology Working Group
Contributions of information and suggestions are welcome!