HydroClim Minnesota - February 2012

A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the Wednesday following the first Monday of each month.

State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: February 1, 2012

What happened in January 2012:

• January 2012 was yet another dry month across much of Minnesota. In many counties, it was the sixth consecutive month of precipitation shortfalls. January precipitation totals generally ranged from one-quarter to three-quarters of an inch, roughly one-third to one-half inch below the historical average.
• Monthly mean temperatures for January 2012 were very warm, topping the historical average by 9 to 11 degrees across Minnesota. Preliminary data indicate that January 2012 will rank among the seven warmest January's in the historical record. It was the fourth consecutive month of abnormally warm temperatures. Extreme temperature values for January ranged from a high of 62 degrees F at Marshall (Lyon County) on the 5th, to a low of -30 degrees F at Brimson (St. Louis County) on the 20th. All-time maximum temperature records were set at numerous locations on January 4, 5, 6, 7, 9, and 10.

Where we stand now:

• The U. S. Drought Monitor, released on January 26, depicts nearly every Minnesota county as experiencing some level of drought. A section of northeast Minnesota is placed in the Severe Drought category. Stream flow and lake levels in those areas are very low due to the ongoing impact of precipitation deficits accrued during the 2010 growing season and spotty precipitation in 2011. The Drought Monitor also places much of southern Minnesota in the Severe Drought category. Nearly all other Minnesota locales are determined to be in Moderate Drought. As a state, the autumn of 2011 was the driest in Minnesota's modern climate record. That precipitation deficit has been followed thus far by a snow-sparse winter. The U. S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc) are based on several indicators.
• The present snow depth is well below the historical median in most Minnesota locations. Snow depths across the northern one-quarter of Minnesota are generally four to eight inches. Some north central and northeast Minnesota stations report eight to 12 inches of snow cover as of this writing. A few spots in northeast Minnesota along the Canadian border and along the Lake Superior Highlands have 12 to 18 inches of snow on the ground. Elsewhere in Minnesota, snow depths are generally one to three inches, with some locations reporting a nearly snow-free landscape.
• The U.S. Geological Survey reports that stream discharge values (where winter monitoring is possible) are very low in northeast and north central Minnesota watersheds. Stream flow values rank below the 10th percentile for this time of year for rivers in the northern tier of Minnesota counties. For the Red River and some of its tributaries, river flow measurements are above the median when compared with historical data for the date, the lingering impact of a wet autumn 2010 and spring 2011.
• The Lake Superior water level is near its elevation of a year ago, but down 13 inches from the long-term seasonal average. Water levels on many Minnesota lakes are low when compared with historical averages.
• In their final report of the season (November 7), the Minnesota Agricultural Statistics Service reported that topsoil moisture was 28% Very Short, 43% Short, 29% Adequate, and 0% Surplus across the state. Dry soils have heightened concerns about the soil moisture profile for the coming growing season. Late-autumn conditions act as a predictor of the soil moisture situation entering a growing season.
• The soil is frozen 16 to 24 inches deep in southern Minnesota and 18 to 30 inches deep in northern Minnesota. Frost depths typically reach their maximum in late February or early March.
• Minnesota lakes are ice covered. However, ice conditions are highly variable. Lake and river ice is NEVER completely safe for walking or driving.

[see: DNR Conservation Officer Reports]

• The potential for wildfires is currently rated by DNR Forestry as Low across Minnesota. It is unusual to discuss wildfire danger in February. However, burning permits are required whenever there is less than 3 inches of continuous snow surrounding the burn area. A snow-sparse winter has produced this scenario in some counties.

[see: Fire Danger Rating Map]

Future prospects:

• The February precipitation outlook presents an equal likelihood of below-normal, near-normal, or above-normal conditions across Minnesota. February is Minnesota's driest month on average with precipitation normals ranging from near one-half inch in northwestern Minnesota to just over one inch in far eastern sections of the state. The median snow depth at the end of February ranges from under 5 inches in southwest Minnesota to over 18 inches on the ground in northeastern Minnesota (greater than 30 inches in the Lake Superior highlands).
• The March temperature outlook tilts towards above-normal conditions, especially in southern Minnesota. Normal February high temperatures range from the low-teens in the north to near 20 in the south early in the month, climbing to the mid-20s to low 30s by month's end. Normal February low temperatures range from near minus 10 degrees in the far north to the single digits above zero in southern Minnesota early in the month; ascending to the low single digits in the north, mid-teens in the south by the end of February.
• The 90-day precipitation outlook for February through April tilts towards above-normal conditions in far northeast Minnesota, with an equal likelihood of below-normal, near-normal, or above-normal conditions elsewhere in the state. The February through April temperature projection demonstrates an equal likelihood of below-normal, near-normal, or above-normal conditions throughout Minnesota.
• The National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. The probability of significant spring flooding in any Minnesota basin is currently thought to be quite low.

From the author:

• Without ample, widespread precipitation in the late winter and early spring, Minnesota will face a number of drought-related issues at the beginning of the 2012 growing season. Other than the scarcity of snow cover, Minnesota's drought presently exhibits relatively few observable negative impacts. The drought situation will become rapidly apparent in the spring in the form of deficient soil moisture supplies and low water levels in wetlands, lakes, and rivers.

Contributions of information and suggestions are welcome!