Preliminary Climate Summary for September

Preliminary Climate Summary for September:

As we near the end of the month it appears that most climate stations will report a mean monthly temperature that ranges from 3 to 5 degrees F above normal, only the 2nd significantly warmer than normal month of 2019. Extremes were 91°F at Marshall on the 18th, and 31°F at Celina (St Louis County) on the 14th.

With respect to rainfall, September of 2019 will be among the six wettest in history on a statewide basis. Many areas received between 5 and 10 inches for the month. There were several new daily rainfall records set during the month, including 4.28" at Lake Wilson and 4.30" at Pipestone on the 12th. At least 70 new daily rainfall records were set within the state climate network during the month. A handful of climate stations reported over 10 inches of rainfall for the month.

Severe Weather on September 24th:

Many parts of Minnesota reported thunderstorms with heavy rain, strong winds, and hail on Tuesday, September 24th. Several reports of 1-inch diamter hail or larger came from around the state, with most of the strong wind reports (up to 80 mph) coming from southeastern counties: Winona, Olmsted, Mower, Dodge, and Wabasha Counties. Parts of Dodge, Olmsted, Winona, and Steele Counties reported between 1 and 2 inches of rain. Across in western Wisconsin a damaging tornado was reported near Elk Mound.

September of 1807:

Alexander Henry was an explorer and trapper for the old Northwest Company of Canada back at the turn of the 19th Century. He explored and lived in the Red River Valley of Minnesota and North Dakota from 1800 to 1808. He camped and built temporary forts in many places along the river, including near Pembina and Drayton, ND as well as Warren, Oslo, and Red Lake Falls, MN. Thanks to his daily weather journal, one of the oldest in our region, we have a written record of the weather in northwestern Minnesota for the period from September 1807 to June 1808.. September, 1807 according to Henry was highly variable. Very sunny and warm early in the month with several days in the 80s F. Thenit turned cool and showery by mid-month with a number of frosts and a hard freeze on the 16th (28 F). Fall coloration and leaf drop came about mid-month, and he observed the migration of geese and swans heading south. September 18th brought every kind of weather according to Henry's journal ....strong winds, heavy rain, hail, and even two inches of snow! This was followed by another hard freeze on the 20th (27 F). The month concluded with yet another freeze on the 28th, followed by light showers and foggy weather through the end of the month.

Henry's journal is a treasure to a historian or climatologist as it is one of the few written records of the daily weather from such an early time period, before settlement of the Red River Valley. He documents a number of spring snow melt floods in the region and remarks about how the floods used to drown hundreds of buffalo which would graze the numerous islands. The 1800-1808 period is still encompassed by the northern hemisphere's Little Ice Age that extended to roughly 1850. In this context it is not unexpected to find that Alexander Henry recorded snows in September and winter snow cover persisting well into the month of May in northern Minnesota.

Weekly Weather Potpourri:

A late September blizzard is increasingly possible this weekend in parts of the northern Rockies, and some lower elevations of Montana, Wyoming and the western Dakotas could see their first snow of the season just days after the official arrival of fall. You can read more from the Weather Underground.

This week’s AGU-EOS bulletin features an interesting article about climate change refugees and illustrates with an example of residents from the Florida Keys leaving their homes and property to move elsewhere.

MPR listener question:

As we enter the month of October, those of us that like cross country skiing were wondering what the state record is for snowfall during the month of October? We figured that you might know.

Answer:

“When I answered this question earlier on the air for MPR I mistakenly made reference to September snowfall rather than October snowfall. I apologize for that. The answer below is absolutely correct.”

There are four places that have had 19 inches of snowfall in the month of October. Those places and the year of record are listed below:
Farmington (Dakota County) 1926
Virginia (St Louis County) 1951
Baudette (Lake of the Woods County) 1916
Mizpah (Koochiching County) 1932

Twin Cities Almanac for September 27th:

The average MSP high temperature for this date is 67 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 47 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 27th:

MSP weather records for this date include: highest daily maximum temperature of 88 degrees F in 1987: lowest daily maximum temperature of 40 degrees F in 1942; lowest daily minimum temperature is 29 degrees F in 1991; highest daily minimum temperature of 65 degrees F in 2013; record precipitation of 0.54 inches in 1947; and there has been no snowfall on this date.

Average dew point for September 27ths 45 degrees F, with a maximum of 67 degrees F in 1905 and a minimum of 24 degrees F in 1951.

All-time state records for September 27th:

The state record high temperature for this date is 97 degrees F at Beardsley (Big Stone County) in 1894. The state record low temperature for this date is 13 degrees F at Beardsley (Big Stone County) in 1893. State record precipitation for this date is 3.50 inches at Wolf Ridge Environmental Learning Center (Lake County) in 1996; and record snowfall of 6.0 inches at Benson (Swift County) in 1942.

Past Weather Features:

September 27, 1894 was the warmest in state history with over 30 climate stations reporting a daytime high of 85°F or greater. It was an interesting day for residents of Mazeppa in Wabasha County, where the morning low temperature was 32°F with frost on most plants, then the afternoon high soared to 86°F.

This is one of the few instances in Minnesota weather history where the same community holds both the statewide maximum temperature record and the statewide minimum temperature record-this occurred at Beardsley, MN (Big Stone County) in back to back years. In 1893, September 27th brought a morning low of just 13 degrees F, while the next year, the same date brought an afternoon high of 97 degrees F. Only in Minnesota!

Over September 26-27, 1942 an extremely early snow storm swept across Minnesota dumping from 3 to 8 inches in many areas. Becker, Willmar, and Long Prairie all received over 6 inches. Temperatures rebounded into the 60s and 70s F over the next two days wiping out the snow quickly and allowing farmers to return to the fields for harvest.

Outlook:

Somewhat cooler than normal temperatures over the weekend with a chance for widely scattered showers. Continued chance for showers next Monday through Wednesday as well, as cloud cover will keep daily highs below normal entering the month of October.