October Weather Update and Lake Superior Climate

October Weather Update and Lake Superior Climate:

Since last Friday, a number of days have brought some rainfall to the state. Many climate stations have reported between a half inch and an inch of rainfall over this time period. A number of communities also reported over an inch of rain during the week. Despite these widespread rainfalls, the area of Moderate Drought (mostly in central Minnesota) expanded from 12 percent to 19 percent of the landscape.

Though it has been cooler this week, October average temperatures are still running from 5°F to 8°F above normal across the state. The climate outlooks still favor generally above normal temperatures for the balance of October as well. As such, this will mark our 5th consecutive warmer than normal October in Minnesota. Further, there are still a number of areas of the state (mostly southern half) that have yet to record their first autumn frost. For leaf peepers, still plenty of fall color to see in the central and southern parts of the state this weekend, according to the DNR. 

Lake Superior climate characteristics:

We have spoken a number of times about the effects that Lake Superior has on the north shore climate of Minnesota. It clearly affects the temperature, wind, precipitation, and cloudiness of north shore communities like Knife River, Two Harbors, Beaver Bay, Silver Bay, Grand Marais, and Grand Portage. But how about the climate over the lake itself? Thanks to the NOAA National Data Buoy Center and the deployment of instrumented buoys on Lake Superior over the past several decades, we are learning more about the climate patterns over the lake itself.

Some examples: along the western edges of the lake, the mean annual surface water temperature is about 43 degrees F. But because water absorbs and surrenders heat energy quite slowly compared to land, the range and variation in monthly temperatures is quite out of phase with the land-based climate stations along the north shore. Average water temperatures in October are warmer than those of June as a result of the time lag effect of summer warming. Maximum water temperatures, ranging from 56 to 67 F typically occur in August, sometimes even early September. The land stations show maximum air temperature values in July. The coldest air temperatures occur in late January and are often well below zero F, while the coldest the lake ever gets is about 31-32 degrees F, a temperature it may hold steady for most of the winter, even into the early part of May in some years. The windiest month on the lake is November (remember the gales of November) with winds of 20 mph or more common in that month, and gusts well over 40 mph. Expectedly, the maximum wave heights also occur in November, with an average value of about 3.5 feet, and extreme values over 15 feet.

The maximum difference between air temperature and water temperature occurs in the months of November and December, when the air temperature may be as much as 20-25 degrees F colder than the water, and in June when the air temperature may be as much as 15 to 20 degrees F warmer. Interestingly enough, this time of year (October) the average air and water temperatures are quite close to each other. For example on Sunday, October 12th the water temperature near the ApostleIslands was 45 degrees F, while the average air temperature at Bayfield, WI (only 3.5 miles away) was 47 F.

An Anniversary Worth Acknowledging....

In the context of a mostly bountiful harvest season in Minnesota, as well as the fact that our state ranks in the top 5 or 6 nationally for economic output of agriculture, I thought I would mention this anniversary.

Tomorrow, October 18th marks the 137th Anniversary of the founding of the University of Minnesota Agriculture School, now known simply as the St Paul Campus (my home for 40 years). Prior to this, the property was known as the university farm, where formal teaching of agriculture began on this date in 1888 with a class of 47 students. The campus was an end point for one of the spurs of the old Twin Cities streetcar system. Today, the campus is home to the College of Food, Agricultural, and Natural Resource Sciences, the College of Biological Sciences, the College of Veterinary Medicine, University of Minnesota Extension, the Raptor Research Center, the Bee Research Lab, the Bell Museum and Planetarium, the Goldstein Museum of Design, the Leatherdale Equine Center, and of course the ClimatologicalObservatory. I am proud to have been a faculty member there for 40 years.

Weekly Weather Potpourri:

New research published in the AGU-Journal of Geophysical Research shows that AI models of the Earth’s atmosphere when coupled with ocean models can provide relatively accurate climate predictions brought by continued increases of carbon dioxide in the atmosphere. This may better help in assessing geographic disparity in the pace of climate change and its consequences.

Earlier this week on Sunday and Monday, western coastal communities of Alaska (between the Bearing Sea and Guld of Alaska0 were devastated by heavy rains, high winds, and coastal water surge brought by the remnants of Typhoon Halong in the Western Pacific Ocean. Some areas of Alaksa reported over 16 inches of rainfall. According to Alaska Public Media, at least 49 village were impacted by this storm and many people were evacuated. It will be a prolonged and major clean up effort to recover.

The BBC reported this week that independent climate advisors to the United Kingdom government have told officials to plan for climate adaptation measures based on exceeding the 2°C goal of the Paris Climate Agreement. With accelerating pace of climate change and lack of aggressive mitigation in green house gas emissions, it is likely the Earth will warm beyond the 2°C that was the previous prevention goal signed on by nations at the Paris Conference. 

MPR listener question:

We have lived just outside of New Ulm in Brown County for the past several years and wondered how often have we had measurable snowfall during the month of October historically? Thought you might know. BTW: love your weekly chats with Cathy Wurzer.

Answer:

We have over 100 years of climate data from New Ulm in the state data base. Overall, measurable snowfall has occurred in October about one third of all years. A record 15.0 inches of snowfall was reported there from a blizzard on October 16 of 1880.. October snowfalls in southern Minnesota are usually short-lived. 

Twin Cities Almanac for October 17th:

The average MSP high temperature for this date is 58 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 40 degrees F (plus or minus 9 degrees F standard deviation).

MSP Local Records for October 17th:

MSP records for this date: highest daily maximum temperature of 84 degrees F in 1910; lowest daily maximum temperature of 33 degrees F in 1930; lowest daily minimum temperature of 22 degrees F in 1952; highest daily minimum temperature of 62 degrees F in 1953; and record precipitation of 1.24 inches in 1879. Record snowfall for this date is a trace in 2004.

Average dew point for October 17th is 38°F; the maximum dew point on this date is 66°F in 1994 and the minimum dew point on this date is 8 degrees F in 1948. 

All-time state records for October 17th:

The state record high temperature for this date is 90 degrees F at Beardsley (Big Stone County) and five other locations in 1910. The state record low temperature for this date is 2 degrees F at Bemidji (Beltrami County) and Cass Lake (Cass County) in 1952. The state record precipitation for this date is 4.02 inches at Georgetown (Clay County) in 1971. A record 7.0 inches of snow fell at Cook (St Louis County) and at Gunflint Lake (Cook County) on this date in 1990. 

Past Weather:

October 16-17 of 1880 brought a blizzard and heavy snowfall to many parts of southern Minnesota. Many areas reported 10-15 inches, with wind whipped snow drifts as high as 20 feet. The storm shut down the railroads in southern Minnesota and deposited enough snow to last until late spring of 1881. This storm was written about by Laura Ingalls Wilder in her novel “The Long Winter.”

Summer type heat prevailed across much of Minnesota on October 17 of 1910. Most areas of the state reported afternoon temperatures in the 80s F. After starting the day with a morning low temperature of 45°F, Campbell (Wilkin County) saw the afternoon temperature climb to 90°F.

Record-setting cold temperatures prevailed on the morning of October 17 in 1952. More than 100 climate stations reported a record daily low temperature with widespread readings in the teens and twenties. Many northern areas of the state reported single digit low temperatures, and Cass Lake reported an afternoon high temperature of only 31°F. 

Outlook:

Partly cloudy to mostly sunny over the weekend with warmer than normal temperatures. Continued warmer than normal on Monday, then a cool down for Tuesday through Thursday next week, with temperatures near normal or a few degrees cooler. There will be chances for showers later on Saturday, and also Tuesday through Thursday of next week in northern areas of the state. A warm-up in temperatures is seen towards next weekend.