Record-setting wet Valentine’s Day
As a prelude to Valentine’s Day this week Minnesota saw many more days of sunshine and warm southwest winds prevail for several days. This brought warmer and more moist air to the state, keeping both daytime and nighttime temperatures well above normal. International Falls set a new record high temperature on February 11th with a reading of 47°F, Tower set a record high on February 12th with 49°F, and Cambridge set a record high of 44°F on February 13th. Many other Minnesota climate stations reported near-record high temperatures over those few days as well. The temperatures helped melt snow eliminated some ice patches leftover on sidewalks and driveways.
Following those mild days, a slow moving low pressure weather system moved up from the Southern Plains States and brought prolonged rainfall on Valentine’s Day (February 14), literally an all-day rain in many places. This is highly unusual for mid-February. Over 100 climate stations set new daily rainfall or precipitation records (where rain was mixed with snow). A sampling of the record-setting amounts shows the widespread geographical distribution:
Grand Marais 0.90 inches
Gunflint Lake 0.73 inches
Two Harbors 0.88 inches
Duluth 0.67 inches
Hibbing 0.60 inches
Cloquet 0.85 inches
Collegeville 0.75 inches
Mora 1.09 inches
St Cloud 0.68 inches
Elk River 1.15 inches
Marshall 0.68 inches
Twin Cities 0.68 inches
Rosemount 1.14 inches
Faribault 1.09 inches
Wells 1.01 inches
Owatonna 1.06 inches
Waseca 0.96 inches
Austin 0.83 inches
Albert Lea 0.91 inches
To illustrate the rarity of this amount of rainfall in the month of February consider that the monthly normal total precipitation (1991-2020) across Minnesota typically only ranges from 0.50 inches to 1.10 inches.
Minnesota Climate Adaptation Partnership Program kicks-off a new seminar series
2023 UMN Climate Adaptation Partnership monthly webinar series resumes on 2/21 at 12pm with a session to learn about the new statewide MN Climate Action Framework that identifies actions to achieve a carbon-neutral, resilient, and equitable future. Individuals who are interested can visit the web site below for details and free registration.
This group of climate adaptation advocates and practitioners is terrific to network with in order to keep up with the latest news in Minnesota about adapting to our changing climate. 
Weekly Weather Potpourri:
The NOAA Climate Prediction Center released new Seasonal Outlooks this week. Two factors that caught my eye were an expected cooler and wetter than normal March, and most importantly improvement, if not complete elimination of Drought across Minnesota by the end of May. This is welcome news for many Minnesota farmers.
The BBC reports that widespread damages occurred, as well as a number of deaths earlier this week as Cyclone Gabrielle pounded the north island of New Zealand with heavy rains. There were widespread power outages and many people had to be evacuated from their homes because of flood waters. Some areas reported over 7 inches of rain and strong winds. In addition a magnitude 6.0 earthquake shook the country late on Wednesday.
MPR listener question:
Isn't it somewhat unusual to have below zero temperatures in the second half of February?
Answer:
Not at all. The long-term average number of nighttime lows below zero F from February 15th to 28th in the Twin Cities is 3 to 4, while up north in places like Bemidji and International Falls it is 5 to 6 times.
Twin Cities Almanac for February 17th:
The average MSP high temperature for this date is 29 degrees F (plus or minus 13 degrees F standard deviation), while the average low is 13 degrees F (plus or minus 14 degrees F standard deviation).
MSP Local Records for February 17th:
MSP records for this date: highest daily maximum temperature of 63 degrees F in 2017; lowest daily maximum temperature of -12 degrees F in 1936; lowest daily minimum temperature of -20 degrees F in 1936; highest daily minimum temperature of 36 degrees F in 1998; record precipitation of 0.32 inches in 2014. Record snowfall is 4.9 inches in 2014.
Average dew point for February 17th is 14°F; the maximum dew point on this date is 44°F in 1981; and the minimum dew point on this date is -26 degrees F in 1942.
All-time state records for February 17th:
The state record high temperature for this date is 67 degrees F at Redwood Falls (Redwood County) in 2017. The state record low temperature for this date is -52 degrees F at Pokegama Dam (Itasca County) in 1903. The state record precipitation for this date is 185 inches at Hokah (Houston County) in 1984. Record snowfall is 13.0 inches at Beaver Bay (Lake County) in 1870.
Words of the Week: Trombe Wall and Thermosiphoning
The Trombe Wall is a kind of thermal storage design feature, named for French engineer, Felix Trombe. It is comprised of a south-facing masonry wall, usually painted black or other dark color separated from the outside air by a glass wall with a spacing in between. As the masonry absorbs solar radiation it warms the air between it and the glass wall setting up a convective circulation. The warm air rises and passes through one-way vented openings in the top of the masonry wall to enter the interior rooms (sometimes assisted by a fan). This movement of the heated air is called thermosiphoning. A secondary source of heating simply comes from conduction of heat through the masonry (or sometime brick) wall to the interior side where it can provide heat even after sunset, since it may take 6 to 8 hours for the heat to move through the wall.
This time of year, with increasing day length and higher sun angles, the heat gain on south facing landscapes or building walls is quite large, even if the air temperature outside is still quite winter-like.
Past Weather:
With abundant snow on the ground an Arctic air mass gripped the state on February 17, 1903 bringing record-setting low temperatures to many areas. All areas of the state reported subzero temperatures. Northern locations were -30°F to -50°F early in the morning. The afternoon high temperature at Crookston was only -14°F.
One of the snowiest weeks ever in the month of February occurred from the 14th to the 20th in 1967 as a series of winter storms brought almost continuous snowfall to many parts of Minnesota. Many climate stations reported from 11 to 20 inches of snowfall. Portions of Meeker and Wright Counties reported over 20 inches. There were many school closures.
With bright, sunny skies and south winds, as well as an absence of snow cover, over 40 Minnesota climate stations reported afternoon temperatures in the 60s F on February 17, 1981. In southwestern Minnesota some farmers were seen tilling their soils or applying manure.
Outlook:
Warming up again over the weekend with temperatures well above normal for this time of year. Increasing clouds in northern sections of the state on Sunday with a chance for snow later in the day. Chance for more widespread snow across the state on Monday. Another chance for snow Wednesday and Thursday with temperatures falling to cooler than normal. Some significant amounts of snow may accumulate. Cooler temperatures will bring several subzero nights for some.
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