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Frost consequences and new seasonal climate outlook

Scattered Autumn frosts reported

 From the DNR-State Climatology Office


Saturday, September 13th brought widespread frost to many areas, with record lows in a few places like International Falls (25 F), Crane Lake (28 F), Grand Meadow (30 F), Windom (32 F), and Waseca (31 F).  Other dates this month brought a handful of frosts.  Overall about 40 percent of the climate observers in the state have reported frost so far this month, with the vast majority in the northern half of the state.  In the southern half of the state frosts have occurred in spots, but many areas remain frost-free.  Hard freezes with lows in the 20s F have been confined to northern parts of the state.  Some corn and soybean fields have been damaged by these frosts because they had not yet matured, but those fields untouched by frost will likely not see a frost threat for the rest of the month.  There is a good discussion of the potential disparity in agricultural consequences from these frosts presented by Extension Faculty in latest edition of Crop News.

New Seasonal Climate Outlooks

The NOAA Climate Prediction Center released new seasonal climate outlooks this week.  The new outlooks favor a wetter than normal October for the Great Lakes Region, including Minnesota.  The expected temperature pattern for the remainder of the autumn season and the winter season as well (October - February) is for above normal temperatures in our region of the country.  The outlooks were based on the formation of a weak El Nino episode this fall, along with dynamical models that consider other climate trends and attributes.

Weekly Weather potpourri:

The People's Climate March will take place in New York City this Sunday (September 21). Starting from Central Park West at 11:30 am EDT organizers expect well over two hundred thousand to participate. A large group from Minnesota will be going.  The March precedes next week's United Nations Climate Summit, scheduled for September 23rd with at least 125 nations in attendance.

Remnants of Tropical Storm Odile were dumping large amounts of rainfall across portions of AZ, NM, and west Texas this week as the moisture plume from this storm got caught up on the westerly wind flow across the southern USA.  Meanwhile, Edouard became a major hurricane in the Atlantic Ocean, but remained far out to sea, and Hurricane Polo formed in the eastern Pacific Ocean off the coast of Mexico and was expected to bring heavy rain to portions of Baja California.

A recent paper by scientists at Montana State University published in Geophysical Research Letters shows that the tornado season is starting earlier in the southern plains states than it did 60 years ago.  In certain areas the peak season for tornado activity has moved earlier on the calendar by as much as 14 days.  You can read more at the Science Daily web page.

Yale Climate Connections if a daily public radio program produced by the Yale Center for Environmental Communication.  It provides a diverse range of topics related to climate science, climate trends, climate change, climate interactions, and climate impacts.

The BBC reports that the first half of September has been the driest in more than 50 years for the United Kingdom with most observers reporting less than 0.04 inches of rainfall.  Temperatures have been running several degrees F warmer than normal as well.

MPR listener question:

 For the past 15 years we have been going to the north shore of Lake Superior in September to catch the fall colors and walk the Superior Hiking Trail.  In 2003 and 2012 we also encountered snow showers.  We wondered how often do north shore observers report snow in the month of September?


 Using the long term climate records for snowfall it appears that the Duluth and Two Harbors areas report at least a trace of snow in September about 30 percent of all years.  It is about 20 percent of all years at Lutsen and Wolf Ridge Environmental Learning Center near Finland, but those climate records are of shorter duration.  For north-central Minnesota communities, Baudette reports September snowfall in about 15 percent of all years while International Falls reports at least a trace of snowfall in September about 40 percent of the time.

Twin Cities Almanac for September 19th:

The average MSP high temperature for this date is 71 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 51 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 19th:

MSP weather records for this date include: highest daily maximum temperature of 94 degrees F in 1895; lowest daily maximum temperature of 48 degrees F in 1901 and 1918; lowest daily minimum temperature is 33 degrees F in 1873 and 1991; highest daily minimum temperature of 72 F in 1891 and 1940; record precipitation of 2.98 inches in 1907; and there was a trace of snow on this date in 1927.

Average dew point for September 19th is 51 degrees F, with a maximum of 72 degrees F in 1907 and a minimum of 25 degrees F in 1937.

All-time state records for September 19th:

 The state record high temperature for this date is 104 degrees F at Beardsley (Big Stone County) in 1895. The state record low temperature for this date is 16 degrees F at Alborn (St Louis County) in 1929. State record precipitation for this date is 6.08 inches at Red Wing (Goodhue County) in 1907; and many places received a trace of snow on this date back in 1991.

Past Weather Features:

 The year 1895 brought the hottest September 19th in state history.  Actually a two-day Heat Wave prevailed over September 18-19, with over 35 climate observers reporting daytime high temperatures of 90 degrees F or higher.  In western counties five communities reported temperatures of 100 degrees F or higher, all of which are still records today.

Widespread thunderstorms brought heavy rains to many parts of the state on September 19, 1907.  Many observers reported over 2 inches of rain, while the east central counties like Washington, Dakota, and Goodhue reported over 4 inches.  Red Wing and Lake City areas received over 5 inches with some flash flooding.

One of the coldest ever spells of mid-September weather occurred over the 17th to the 19th in 1929.  Hard freezes occurred all the way from the Canadian border to the Iowa border, bringing an abrupt end to the growing season.  Most northern communities recorded minimum temperatures in the teens F, while it was as cold as 25 degrees F as far south as Grand Meadow and New Ulm.

September 18-19, 1991 brought snow to many parts of Minnesota, along with slippery driving conditions.  The Duluth area reported nearly 2.5 inches of snow.


Generally warmer than normal temperatures into the weekend with a chance for showers and thunderstorms in eastern sections of the state.  Drier much of next week with near normal temperatures, warming to above normal towards the end of the week.

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