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Extension > Minnesota WeatherTalk > Mixed climate patterns in December

Friday, December 15, 2017

Mixed climate patterns in December

Mixed climate patterns in December:


After an extraordinary warm start, with scores of record high temperature values set on the 4th of the month, December has been tracking with alternating periods of below and above normal temperatures. Overall through the first half of the month most climate stations are showing average temperature values that range from 4 to 8 degrees F warmer than normal, a trend that is likely to make December the 10th month of 2017 with above normal temperatures. Over 60 climate stations so far have reported subzero low temperatures on at least one day this month, with a minimum of -19°F near Ely earlier this week on the 12th. Embarrass was -15°F on that date as well. Eveleth reported -9°F on December 8th, the coldest in the nation.

Most observers have so far reported anywhere from 5 to 7 days with measurable snowfalls, mostly light in amounts from a dusting up to 1 inch. Though most climate observers have reported a total of just 1 to 4 inches so far this month, some northern climate stations have reported over 10 inches, including Kabetogama, Ely, Isabella, and Baudette.

Nocturnal Character of Winter Storms:


Frequencies of hourly precipitation from the Twin Cities climate records show some interesting daily patterns with respect to the onset of winter storms. Patterns in the hourly frequencies of precipitation do vary by month. In the winter months, December through February, the afternoon hours from noon to 4:00 pm show the lowest relative frequency of measured precipitation. Overnight frequencies of hourly precipitation are relatively higher, especially from 1 am to 6 am. This could be due to the relationship between temperature and the saturation of the air. Low temperatures usually occur during these overnight and predawn hours and probably remain closer to the dew point temperature, preserving the structure and continuity of precipitation, whether droplets, sleet or snow crystals. The other feature of winter storm systems to remember is that they are usually large and take some time to move across the area. Precipitation may last for several hours and since most of our 24 hour calendar day is in darkness during the winter, we associate the storminess with the night.

Reminder of Mn/DOT's winter driving tips:


Call 511 or go to www.511mn.org before departing on a trip to get current road conditions
Drive with headlights on and seat belt fastened
Turn off cruise control
Drive at slower speeds, and keep greater distance between vehicles
Never drive into a snow cloud
Respect snowplows, and stay on the road behind them


Weekly Weather Potpourri:


In the Western Pacific Ocean, Tropical Storm Kai-Tak was spinning southeast of the Philippines and expected to bring rain, strong winds, and high seas to portions of that country by this coming Sunday. It was not expected to strengthen into a typhoon.

The BBC reported this week on a project to map the continent of Greenland and how it would appear without any ice cover. The animated map depictions shows river valleys and mountain ranges underneath the massive ice sheet, which represents a volume of ice that is calculated to be 2.9 million cubic km (about 700,000 cubic miles).

Scientists from Ohio State University have collaborated with scientists from China to extract the largest ice core ever from a non-polar region. They extracted a 1000 foot long ice core from the Tibetan mountains and hope to reconstruct temperature and climate behavior over the past 600,000 years. So far their early results suggest a rapid increase in temperature and precipitation over the past 50 years or so.

A recent paper from scientists at the Universityof Colorado suggests that climate change may dictate a shift in the geographic deployment of wind energy technologies. Their studies of model depicted climate change suggest that wind power resources (based on estimate changes in mean wind speeds) in the mid-latitudes of the Northern Hemisphere may decline over the next century or so, while wind power resources may increase in the Southern Hemisphere and the tropics.


There is an interesting article by NOAA’s Deke Arndt this week about the changing climate on the North Slope of Alaska. Climate change is much more accelerated and significant there according to recent measurements.

MPR listener question:


I am doing a Science Fair Project for school about snowfall and wanted to know how often December is the snowiest month of the snow season (Oct-Apri) for the Twin Cities? I am guessing that it is less than a third of the time.

Answer:


Since 1884 when the Twin Cities daily snowfall record began, December has been the snowiest month of the snow season (Oct-Apr) 31 times (23 percent). If you want the rest of the historical distribution it goes like this......

November 15 times (11 percent)
December 31 times (23 percent)
January 36 times (27 percent)
February 17 times (13 percent)
March 29 times (22 percent)
April 5 times (4 percent)

BTW from 2007 to 2011 December was the snowiest month every winter. You can read more about Twin Cities snowfall record at the Minnesota State Climatology Office web site.

Twin Cities Almanac for December 15th:


The average MSP high temperature for this date is 27 degrees F (plus or minus 13 degrees F standard deviation), while the average low is 12 degrees F (plus or minus 13 degrees F standard deviation).

MSP Local Records for December 15th:

MSP records for this date include: highest daily maximum temperature of 51 degrees F in 2014; lowest daily maximum temperature of -5 degree F in 1932; lowest daily minimum temperature of -21 degrees F in 1901; highest daily minimum temperature of 39 degrees F in 1928; record precipitation of 0.71 inches in 1902. Record snowfall on this date is 7.0 inches in 1902.

Average dew point for December 15th is 10°F; the maximum dew point on this date is 39°F in 1928; and the minimum dew point on this date is -22°F in 1963.

All-time state records for December 15th:


The all-time state high temperature for today's date is 60 degrees F at Marshall, Springfield, and Tracy in 1939 and again at Canby in 1998; the all-time state low for today's date is -47 degrees F at Pokegama Dam (Itasca County) in 1901. The all-time state record precipitation for this date is 2.25 inches at Grand Rapids (Itasca County) in 1893. Record snowfall is 14.6 inches at Rockford (Wright County) in 1996.

Past Weather Features:


We know from the Ft Snelling clmate record that December of 1855 was no picnic. Well, actually maybe you could have had a picnic during the first days of the month as temperatures reached the mid 40s F. But following that mild spell a series of arctic fronts descended across the region bringing measurable snowfalls on nine days and an especially heavy snow at mid month. Friday and Saturday, December 15th and 16th brought snow "with flakes as big as a featherbed" totaling 8 to 12 inches around the St Paul area. Sleighing was said to be excellent as total snowfall amounted to 22 inches for the month. The fresh snow cover and arctic air produced one of the coldest Christmas Eves in Minnesota history with a reading of -33 degrees F at Ft Snelling, -36 degrees F at St Paul, and -38 degrees F elsewhere in southern portions of the state. So after a teasing, mild start what a bitter month it turned out to be.

A rare December rain occurred across southern Minnesota on December 15, 1894. With daytime temperatures in the 40s and low 50s F and no snow on the ground, rainfall amounts ranging from half an inch to 1.50 inches (at St Peter and New Ulm) were observed across the southern half of the state.

On December 15, 1901 an Arctic air mass brought record cold to the state. Over 20 climate stations reported minimum temperatures of -30°F or colder, while the daytime high at Pine River Dam only reached a reading of -12°F.

On December 15, 1919 another Arctic air mass brought record-setting cold temperatures to parts of Minnesota. Over 30 climate stations reported a minimum of -30 degrees F, including Rochester in southern Minnesota. The daytime high at Roseau and Hallock was just -15°F with 10 inches of snow on the ground.

A strong winter storm brought 6-15 inches of snow to many parts of Minnesota on December 15, 1996. Snowplows were kept busy into the night trying to keep roads and highways open. Many climate stations reported over 30 inches of snow that month, and Two Harbors received 49 inches.

By far the warmest December 15th on a statewide basis was in 1998. Over 60 climate stations reported a daytime high of 50 degrees F or greater. Even as far north as Gunflint Lake reached a high of 52°F. The temperature never dropped below 36°F at Winona and Minnesota City along the Mississippi River Bluff Country.

Outlook:


Temperatures a few degrees warmer than normal for the weekend and early next week, with some highs above the freezing mark on Monday and Tuesday. An increasing chance for snow later on Wednesday and into Thursday, followed by cooler than normal temperatures towards the end of the week.

 

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