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Cold temperatures, dry air

Cold temperatures, dry air

Both Tuesday and Wednesday brought cold temperatures to many northern Minnesota communities. High pressure, clear skies, and a dry air mass were conducive to significant overnight drops in temperature. Some communities set new low temperature records, including

For Tuesday, September 18th:
32 degrees F at Grand Forks, ND
28 degrees F at Wright
27 degrees F at Floodwood
26 degrees F at Kabetogama
24 degrees F at Orr
22 degrees F at Hibbing
21 degrees F at Babbitt
20 degrees F at International Falls and Embarrass
19 degrees F at Warroad (this was the lowest reading in the nation on September 18th)

For Wednesday, September 19th:
27 degrees F at Silver Bay and Grand Marais
25 degrees F at Kabetogama
23 degrees F at Orr
21 degrees F at Warroad
20 degrees F at Embarrass (this was the lowest in the nation on September 19th)

The air was so dry that dewpoints were in the low 20s F, far more typical of late November than mid-September. After relative humidity in many places ranged from 20 to 30 percent. As a result of the very dry air and windy conditions during the day, the National Weather Service issued a number of Red Flag warnings this week around the state.

More overnight temperatures in the 20s and 30s F are expected over the coming weekend.

Windy Wednesday

A moderately strong low pressure system passing across southern Canada on Wednesday brought high winds to Minnesota. Most locations reported winds up to 30 mph or greater, while a few saw winds exceed 40 mph. Those reporting winds between 40 and 45 mph included Glenwood, Park Rapids, Detroit Lakes, Thief River Falls, Madison, Willmar, and Windom. Winds were strong enough to temporarily stop field harvesting of the corn crop in some areas during the late afternoon period.

New climate outlooks

On Thursday of this week the NOAA Climate Prediction Center issued new seasonal climate outlooks. The temperature outlook for Minnesota favors above normal values over the October-December period. Actually this trend is seen for about 75 percent of the USA based on dynamical models and past trends. Little emphasis is placed on El Nino at the moment because it remains in a neutral state. The precipitation outlooks shows equal chances for above or below normal values over the October-December period across most of the USA except the southeastern and mid-Atlantic states which are expected to see above normal values.

Weekly Weather potpourri

Excerpt from this week's report out of USDA/OCE-World Agricultural Outlook Board......
"Crops and cattle in drought continued to rise. Overall, drought has shifted toward the north and west in recent weeks.
-U.S. corn in drought stands at 85%, up a percentage point from a week ago. The corn harvest is underway, 26% complete nationally by September 16.
-Soybeans in drought also rose a point – to 82%. The soybean harvest has accelerated, and stood at 10% complete nationally as of September 16.
-Hay in drought likewise rose 1 point to 67%, eclipsing the 66% high set on July 17 and 24.
-Cattle in drought reached a new high, rising 1 point to 75%.
-Winter wheat in drought was added last week, as planting is underway (11% complete). Nearly three-quarters (74%) of winter wheat areas are in drought.
-Due to expansion of drought in the nation’s mid-section, contiguous U.S. drought coverage reached a record-high 64.82% on September 11, eclipsing last week’s mark of 64.16%. The former record of 63.86% had been set earlier in the summer on July 24.
-The forecast features little if any rain over the next 5 to 7 days in most of the severe-to-extreme drought areas, particularly the Great Plains."

A new analysis of climate models published this week reveals both their strengths and their weaknesses.....according to the Science Daily web site..."the study is one of the first to systematically address a long standing, fundamental question asked not only by climate scientists and weather forecasters, but the public as well: How good are Earth system models at predicting the surface air temperature trend at different geographical and time scales?" This paper, written by Dr. Xubin Zeng (University of Arizona) and his research colleagues is published in Journal of Geophysical Research-Atmospheres shows that climate models have skill in depicting climate patterns across multiple decades (at least 3 or more), and at continental spatial scales. The models are not so good at year by year, or decadal scales. You can read more here.

The International Cloud Appreciation Society is advocating for the naming of a new cloud type, "undulatus asperatus" (aka "agitated waves") which have been photographed in a number of places, including Cedar Rapids, Iowa. It is distinctive looking wave form cloud which Gavin Pretor_Pinney, President of the Cloud Appreciation Society thinks is deserving of recognition in the world cloud atlas published by the World Meteorological Society. You can read more about it here.

Incidentally, the Cloud Appreciation Society announced recently the availability of its 2013 Cloudspotting Calendar. You can order one online by going to their web site.

The National Snow and Ice Data Center (NSIDC) in Colorado announced this week that satellite monitoring of the Arctic Sea this month showed the lowest level of sea ice measured in the satellite monitoring era (since 1979). The new record minimum is almost 300,000 square miles less than the previous record low amount measured in September of 2007. You can read more here.

MPR listener question

I saw where Paul Huttner mentioned a chance for snow showers earlier this week. I have never seen a September snow here. How often does the Twin Cities see a September snowfall?

Answer: In the modern National Weather Service records for the Twin Cities which date back to 1891, there are 13 reports of September snowfalls of a trace or greater, three of which came in September of 1942. In the older Pioneer Era records for the Twin Cities (1820-1890) there were only 4 reports of a trace of snowfall in September. The most recent measurable amount of snowfall was September 24, 1985 when 0.4 inches was reported at MSP International Airport. So historically you could say that September brings at least a trace of snowfall to the Twin Cities only about 8-9 percent of the time, once every 12 years or so.

Twin Cities Almanac for September 21st

The average MSP high temperature for this date is 70 degrees F (plus or minus 10 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 21st

MSP weather records for this date include: highest daily maximum temperature of 94 degrees F in 1937 lowest daily maximum temperature of 46 degrees F in 1913 and 1995; lowest daily minimum temperature of 32 F in 1974; highest daily minimum temperature of 66 F in 1891 and 1908; and record precipitation of 2.07 inches in 1986; Record snowfall is a trace in 1995.

Average dew point for September 21st is 46 degrees F, with a maximum of 69 degrees F in 1924 and 1970 and a minimum of 22 degrees F in 1974.

All-time state records for September 21st

The state record high temperature for this date is 101 degrees F at Wheaton (Traverse County) in 1937. The state record low temperature for this date is 13 degrees F at Alborn (St Louis County) in 1934. State record precipitation for this date is 3.95 inches at Lamberton (Redwood County) in 1968; and the state record snowfall for this date is 0.5 inches at International Falls (Koochiching County) and Walker (Cass County) in 1974 and at Park Rapids (Hubbard County) in 1995.

Past Weather Features:

Heavy late season thunderstorms brought very heavy rains to some parts of Minnesota on September 21, 1870. Ft Snelling reported 1.70 inches, while Ft Ripley reported 3.06 inches and Litchfield received 3.80 inches, still a record for the date in that community.

September 21-22, 1895 saw heavy thunderstorms cross the southern part of the state dropping 2 to 5 inches of rainfall and flooding many fields around Hutchinson, Worthington, and St Cloud. Harvest was delayed for many days in those areas.

September 21, 1904 brought an abrupt end to the growing season with many observers reporting temperatures in the 20s F. Pokegama Dam fell as low as 15 degrees F. Near Worthington the temperature dropped to 29 degrees F damaging some recently harvested potatoes.

September 21, 1934 brought another hard freeze to the state with many observers reporting temperatures in the 20s F, as far south as St Peter. Pokegama Dam reached a low of 15 degrees F, tying their record for the date.

September 21, 1937 was the hottest on record with over 24 communities reporting daytime highs between 90 and 98 degrees F. For many it was the latest seasonal reading of such high temperatures.

September 21-22, 1986 was notable for the thunderstorms which disrupted harvesting in many southern Minnesota counties. Areas from Austin and Zumbrota, north to Farmington were his with 2-4 inch rainfalls. Zumbrota (11.72 inches) and Red Wing (11.51 inches) ended up with record amounts of September rainfall that year.

September 21, 1995 was cold with temperatures in the 30s and 40s F in northern Minnesota communities. Brief snow showers brought some areas a trace up to 1 inch of snowfall. Baudette reported a record amount of 2.0 inches.


Cooler than normal weekend coming up, with a chance for frost/freeze on Saturday night in many areas (that have yet to see one). Warming up on Monday to near normal temperatures with little chance for significant precipitation next week under mostly sunny skies.
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