|HydroClim Minnesota - March, 2000
A monthly electronic newsletter summarizing Minnesota climate conditions and the resulting impact on water resources.
Distributed on the Wednesday following the first Sunday of each month.
State Climatology Office - DNR Waters
WHAT HAS HAPPENED:
- to reiterate from the January and February HydroClim newsletters ...
the last quarter of 1999 (October 1 - December 31) was extraordinarily dry across most of
Minnesota. Many western Minnesota communities were at or near all-time record low
precipitation totals for the period. The lack of precipitation created deficits in surface
hydrology normally benefitting from autumn recharge.
- precipitation totals for the month of February ranged from 0.5 inch in
north central Minnesota to 1.5 inch in east central counties. These relatively small
precipitation totals were nonetheless near or above the average for the historically dry
month of February. On February 15, a winter storm dropped freezing rain and snow on
southern Minnesota, and five to ten inches of snow on some northern counties. A storm
system passed over the region on February 23, bringing thunder and rain, unusual phenomena
for the month of February. Areas of southern and central Minnesota reported rainfall
amounts ranging from 0.25 to 0.50 inches. Faribault, MN reported 0.51 inches and Sioux
Falls, SD reported 0.77 inches, new record amounts for the date. The rainfall, along with
warm temperatures, led to a remarkably rapid loss of snow cover across Minnesota. By
month's end much of Minnesota was snow-free, an unusual condition for the end of February.
Across northern Minnesota a snow-free condition at the end of February is very rare (1%
- February temperatures were extraordinarily warm throughout Minnesota,
ranging from nine to twelve degrees above the normal for the month. Many daily temperature
records were broken, and some locations reported temperatures which tied or broke all-time
highs for the month of February. This marked the fourth consecutive month of above average
temperatures. February 2000 also continued a striking trend in February temperature
patterns. Eight of the past eleven Februarys have seen temperatures well above normal on a
statewide basis. The past three consecutive Februarys rank in the ten warmest
historically. Minnesota experienced remarkable warmth during the first week of March as
well. Temperatures soared into the 60's and 70's on March 4th, 5th, 6th, 7th and 8th,
breaking many maximum temperature records. Maximum temperatures in the 70's have occurred
during the first week of March in only seven years of Minnesota's 110 year modern climate
WHERE WE STAND NOW:
- the National Drought Mitigation Center continues to classify
southwestern Minnesota in their "D2" category ("Severe Drought - crop or
pasture losses likely; fire risk very high; water shortages common; water restrictions
imposed"). Much of the remainder of Minnesota remains in the "D1" category
("First Stage Drought"). The NDMC index is a blend of science and subjectivity
where intensity categories are based on six key indicators and numerous supplementary
- the Palmer Drought Index places southwestern Minnesota in the moderate
drought category, and near normal elsewhere. The Palmer Drought Index is used for
assessing long-term meteorological conditions.
- soil moisture conditions seldom change substantially during the winter. However, the warm temperatures of February and early March thawed topsoil and allowed for infiltration of melting snow and falling rain. In spite of this recent recharge, topsoil moisture likely remains short in many locations due to the dry autumn weather. In southwestern Minnesota, soils are very dry throughout the rooting zone. Most other areas of Minnesota have average to moist middle and lower soil layers.
- current stream flow data show average to above average discharge
values across Minnesota. However, this year's unique climate regime must be noted when
comparing present stream flows to historical averages. In most years at this point of the
season, streams are not ice-free, the snow pack is mainly intact, and subsurface and tile
drain flows are minimal. Without significant precipitation over the next few weeks, stream
flow levels will show a significant drop relative to historical averages.
- as mentioned previously, all of Minnesota is snow-free as of this
writing. All northern Minnesota counties are at or near all-time record low snow depths
for this point in the winter. Three consecutive snow-deficient winters in the north has
led to economic hardship for those in snow-dependent industries.
- frost rapidly left the soil during the warm spell in late February and early March. Many soils are completely free of frost. In other areas where frost remains in the ground, the top 12 or more inches of soil is thawed.
- many of the smaller lakes in south central and southwestern Minnesota are now ice-free. This is approximately three weeks ahead of the historical average. Ice conditions elsewhere are deteriorating rapidly.
- water levels in many wetland complexes are quite low, or in many cases the wetlands are completely dry.
- because of the early loss of snow cover and recent record high temperatures, the wildfire season that typically begins around April 1, has arrived a month early.
- the 30-day outlook from the Climate Prediction Center calls for
near-normal precipitation and near-normal temperature for the month of March. The 90-day
outlook for March through May tilts towards above-normal temperatures. The 90-day
precipitation outlook indicates a tendency towards above-normal precipitation in the north
and near-normal precipitation in the south.
- the spring flood outlook from the National Weather Service - North
Central River Forecast Center calls for crests below flood stage for all of Minnesota's
major basins. The outlook is based on assumed normal conditions for the remainder of the
- (REPEATED FROM LAST MONTH) from agricultural climatologist Mark Seeley ... "Drought which begins in the fall season is typically less consequential than drought which begins in the winter, spring or summer. Winter drought can cause desiccation of plants, and winter injury to pasture grasses, winter wheat and alfalfa. Spring drought can cause delayed crop planting and emergence and/or significant soil loss from wind erosion, while summer drought can stunt plants, cause drastically reduced crop yields, and very low river flows that present navigation problems. The current dry conditions can yet be mitigated in two ways: (1) by heavy overwinter snow cover which will infiltrate into the dry soil layers with each thaw cycle of the late winter; or (2) by early spring precipitation which will recharge the depleted surface layers of the seedbed and perhaps bridge the dry layers of the root zone with the more saturated layers of soil below. Thus, though the current lack of soil moisture in parts of Minnesota is of concern, there are still a number of ways that the soil could be recharged sufficiently for the year 2000 crop season."
- (REPEATED FROM LAST MONTH) foresters are concerned about the potential for a major burn in the BWCA. Many trees blown down by the July superstorm rest on their larger branches, keeping most of the heavier fuel off the ground. This architecture, plus a lack of shade, creates an excellent drying condition. A modest dry spell in future growing seasons will lead to high forest fire danger in that area.
A THOUGHT FROM THE AUTHOR (REPEATED FROM LAST MONTH):
- for many locales, the decade of the 1990's was the wettest of the 20th
century. An entire generation of water resource professionals have experienced only water
abundance or water surplus. We must remind ourselves that water DEFICITS are part of
Minnesota's climate and will inevitably occur in the future. All water resource planning
efforts must acknowledge this fact.
NOTES FROM THE FIELD:
- Ottertail County: Ice conditions are deteriorating rapidly in west central MN. I was on the ice over the weekend on two different lakes and will not venture forth again, regardless of how good fishing was. You can bounce on the ice and see the water move in the holes. There have been two or three reports I am aware of where guys have gone through near the shore. The larger wetlands have 20-30 ft. of open water around them, and smaller wetlands are wide open, if they have water. Spring fishing was a short season this year.
UPCOMING DATES OF NOTE:
- March 16, Climate Prediction Center releases 30/90 day outlooks
WEB SITES FEATURED IN THIS EDITION:
http://climate.umn.edu - Minnesota
Climatology Working Group
Dana Dostert, DNR Waters Hydrologist - St. Paul
Contributions of information and suggestions are welcome!