|HydroClim Minnesota - February 2001
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
- January precipitation was near to above normal
across the southern two thirds of Minnesota, below normal in the northern
third of the state. January precipitation totals exceeded one inch in many
southern and central Minnesota communities, primarily due to a significant
rain/ice/snow storm which struck Minnesota on January 29 and 30. Up to
that point, January precipitation had been quite light.
- in sharp contrast to December, January
temperatures were mild. Temperatures across Minnesota averaged 6 to 12
degrees above normal. For many communities, January 2001 temperatures were
warmer than the Januaries of the previous three mild winters.
WHERE WE STAND NOW
- although January was mild, temperatures remained
cold enough to retain most of the snow cover accumulated during November
and December. The snows of late January added to the snow pack, leading to
snow depths exceeding 12 inches across large areas of Minnesota by month's
end. Snow depths in the southwestern third of Minnesota rank above the
80th percentile for the date, and snow depths for the remainder of the
southern half of Minnesota are above median. Snow depths for the northern
half of Minnesota are at or below the median.
- snow water equivalent data gathered by the
National Weather Service show that the snow pack across Minnesota
generally contained two to three inches of water as of February 5.
- frost depths across the state range from near zero
to 12 inches in areas receiving early and persistent snow cover, 24 to 36
inches in areas blown free of snow.
- 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 many points
in the Red River basin are above the 90th percentile when compared to
historical values for the date. Stream flows in other areas of the state
are near to above average for the date.
- as of their February 1 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 February 3 Palmer Drought Severity Index
(PDSI) depicts most of Minnesota in the "Near Normal" category.
Counties in northwest, south central, and southeast Minnesota are
categorized as experiencing an "Unusual Moist Spell". The Palmer
Drought Severity Index is used for assessing long-term meteorological
- the 30-day outlook from the Climate Prediction
Center shows no significant tendencies (equal chances of below, near, and
above normal) in February precipitation for nearly all of Minnesota.
February is the year's driest month on average with normal precipitation
values ranging from one half to three quarters of an inch. The February
temperature outlook is also indeterminate for almost the entire state.
Normal February high temperatures are in the upper teen's to low 20's
early in the month, rising to the upper 20's and low 30's by month's end.
Normal February lows average near zero to start the month and climb to
around 10 degrees as the month ends.
- the 90-day precipitation outlook for February
through April offers no deviation from the climatological probabilities
across the state. The February through April temperature outlook calls
shows no significant tendencies for all but far northeastern Minnesota. In
the northeast, the outlook favors near normal conditions.
- the National Weather Service now produces
long-range probabilistic river stage and discharge outlooks for the Red
River and Minnesota River basins. A hydrologic model is initialized using
the current conditions of the river, water equivalent of the snow cover,
and soil moisture. The model is then 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 of temperature and
precipitation. The model output is 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
Services (AHPS) and will be produced near the middle of each month. The
AHPS service will be available for the Mississippi River Basin in the
autumn of 2002.
FROM THE AUTHOR
- the U.S. Geological Survey is testing a new Web site designed to offer water resources data for Minnesota (and other states). See: http://water.usgs.gov/mn/nwis . The USGS would appreciate comments from water resources professionals.
NOTES FROM AROUND THE STATE
UPCOMING DATES OF NOTE
- February 15, Climate Prediction Center releases
30/90 day outlooks
WEB SITES FEATURED IN THIS EDITION
- Minnesota Climatology Working Group
- Greg Mitton, U.S. Geological Survey - Mounds View
Contributions of information and suggestions are welcome!