Final Days of February Cold Wave

Final Days of February Cold Wave:

As we face the final days of this somewhat long winter Cold Wave in Minnesota, I was inspired to see these words from the writer Victor Hugo:

"laughter is the sun that drives winter from the human face."

Wind Chill values ranged from -35°F to -48°F this week as the National Weather Service had to issue many Cold Weather Advisories and Extreme Cold Warnings. A number of school districts called off school or started late as a result of the cold weather this week.

Most places in the state have recorded average temperatures so far this month that are 8°F to 12°F colder than normal, with a majority of nights bringing subzero temperatures. Eighteen of the first twenty days of the month have brought subzero low temperatures to International Falls. Within the state climate station network, over 20 new record daily low temperatures have been set, including -37° F at Brimson on February 12th, -41°F at Ely on February 17, and -31°F at Brainerd on February 18th. And these recording setting cold minimum temperatures have come shortly after record-setting daily high maximum temperatures (many days in the 50s F) were recorded around the state over January 28-31.

Minnesota has reported the coldest temperature in the nation 6 times so far this month, with many morning lows ranging from -30°F to -40°F. The persistent cold has pushed soil frost depths down close to 40 inches in many areas.

Beginning this Saturday a warming trend will prevail across Minnesota raising daily temperatures to above normal levels in most places. For the last week of the month (Feb 22-28) temperatures around the state will average 10°F to 15°F above normal. So in this context our soil frost depth has likely reached its maximum for the winter, and in some areas of the state we may see no more subzero temperatures.

Weekly Weather Potpourri:

This week’s AGU-EOS Bulletin has an interesting story about the study of postfire debris flows that are triggered by heavy rains following wildfires that have denuded the landscape. These debris flows and mudslides can be quite damaging and more scientific study of them is certainly warranted and would help communities to find ways of mitigating these hazards, as the frequency of wildfires is increasing in many geographic areas with climate change.

The BBC reports this week, that scientists may have found a way to scale up fog harvesting in the more arid regions of Chile, so that enough fresh water can be harvested to provide city needs. What is fog harvesting? “A mesh is hung between poles, and when the moisture-laden clouds pass through that fine mesh, droplets form. The water is then channeled into pipes and storage tanks.” Some arid climates of Chile receive little rainfall annual (less than a quarter inch), but there experience a great number of foggy days. So, this type of atmospheric water harvesting may work well there.

The Weather Underground reports this week from a recent study that “91% of the 232 U.S. locations analyzed saw a drop in the annual number of freezing nights since 1970. An average of 15 fewer freezing nights were observed, which is part of a larger trend in cool season warming and shorter winter months altogether.” The most rapid winter season warming has occurred in colder areas of the USA, including Minnesota.

MPR listener question:

For the last two weeks you have remarked about the cold temperatures around the state, but also stated that these were not “historically cold”readings. Exactly what do you mean by “historically cold” readings?

Answer:

I mean that in historical context the cold temperatures are no where near as prolifically record-setting as some past Februarys, nor does the longevity of the cold rank among the longest Cold Waves historically. For context our average statewide temperature so far this February is between 3°F and 4°F. But, back in 1936 the statewide average temperature for the entire month of February was -7.2°F. So far this month the state climate station network has reported about 25 new record minimum temperatures, while back in February of 1936 there were 295 daily low minimum temperature records set. International Falls has reported 19 subzero mornings so far this February, but back in February of 1875 Camp Ripley reported subzero low temperatures on 27 out of 28 days.

Twin Cities Almanac for February 21st:

The average MSP high temperature for this date is 31 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 15 degrees F (plus or minus 13 degrees F standard deviation).

MSP Local Records for February 21st:

MSP records for this date: highest daily maximum temperature of 62 degrees F in 2017; lowest daily maximum temperature of -1 degrees F in 1963; lowest daily minimum temperature of -21 degrees F in 1873; highest daily minimum temperature of 44 degrees F in 1930, and record precipitation of 0.82 inches in 1882. Record snowfall is 5.5 inches in 1962.

Average dew point for February 21st is 13°F; the maximum dew point on this date is 52°F in 1930 and the minimum dew point on this date is -33 degrees F in 1963.

All-time state records for February 21st:

The state record high temperature for this date is 64 degrees F at Redwood Falls (Redwood County) and Amboy (Blue Earth County) in 2017.. The state record low temperature for this date is -51 degrees F at Meadowlands (St Louis County) in 1939 and at Baudette (Lake of the Woods County) in 1966. The state record precipitation for this date is 2.02 inches at Two Harbors (Lake County) in 2014. The statewide snowfall record for this date is 19.2 inches at Madison (Lac Qui Parle County) in 2011.

Past Weather:

A large, slow-moving winter storm dropped 10 to 17 inches of snow on western Minnesota communities on February 21 of 1953. Some places reported over 30 inches of snow on the ground that month.

With little or no snow cover, over 30 southern and western Minnesota climate stations reported record-setting high maximum temperatures on February 21 of 1981. Several counties reported afternoon high temperatures in the 60s F and some farmers were seen working their fields.

An Arctic Air Mass brought record-setting low temperatures to many parts of Minnesota on February 21 of 1939. Over 30 climate stations reported record low minimum temperatures, including several communities reporting -40°F or colder. The high temperature at Detroit Lakes only reached -10°F.

Outlook:

Mostly sunny this weekend with temperatures climbing to above normal levels across the state. Slight chance for rain or snow in the far north on Sunday. Temperatures will remain well above normal most of next week, cooling down towards the first weekend of March. There will be periodic chances for rain/snow showers during the week.