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Near Historic Heat for the Growing Season

Near Historic Heat for the Growing Season:

Michelle Margraf of the NOAA-NWS Office in Chanhassen put me onto the near historically warm growing season we have been having in Minnesota so far in 2018. Since May 1st, often considered the beginning of the growing season we can look at temperature patterns since that date in 2018. May was nearly 6 degrees F warmer than normal on a statewide basis, while June was nearly 3 degrees F warmer than normal. So the combination of May-June in 2018 produced the 4th warmest start to the growing season in state history, averaging 4.5 degrees F warmer than normal. Only 1934, 1977, and 1988 were warmer.

Now so far for July the average temperature across the state is nearly 4 degrees F warmer than normal, with extremes of 96 degrees F at Gaylord and 41 degrees F at Brimson. Heat Index values (a measure of warmth which considers both temperature and dew point) have soared up to 105 to 120 degrees F around southern Minnesota already this month. If this pattern of warmth persists throughout the balance of July then we will record the warmest May-July period in state history. Fortunately the second half of July looks to be near normal or cooler than normal, so we will fall off this record-setting pace.

Nevertheless both Michelle Margraf and Dr. Kenny Blumenfeld have noted the for the Twin Cities it has been the 3rd warmest growing season so far (May 1 to July 9th) trailing only 1934 and 1988 (see graphic below). BTW this is mostly due to unusually warm minimum temperatures, rather than unusually warm daytime maximum temperatures, a trend we have been observing with climate change. The warm nights have promoted good production of many vegetable crops, beans and squash being two of them. Elsewhere, especially in south-central and southwestern counties, 4 to 9 inches of rain has inundated many agricultural crop fields. As recently as Thursday, July 12th some areas of east central and northeastern Minnesota reported 3 to 5 inch rains.

Weekly Weather Potpourri:

Speaking of heat, most Minnesota citizens know the common risks associated with NWS Heat Advisories and Excessive Heat Warnings, dehydration, heat exhaustion, etc. But in recent years studies from European scientists (via LiveScience) have documented how Heat can trigger other health risks like gastroenteritis (flu-like symptoms) and inflammatory bowel disease (Crohn’s Disease). My wife Cindy Bevier put me onto this from an article on the web.

This week NOAA scientists feature an article about the sharp decline in Great Lakes ice cover over the past four decades. The greatest declines have been in Lake Superior, Huron, St. Clair, and Erie.

A recent Heat Wave and Drought in Ireland has revealed an ancient relic from 5000 years ago, seen as a pattern in the soil and vegetation. The circle or henge pattern revealed in the landscape will be studied by anthropologists and archeologists. This story is featured by the BBC Weather Center.

MPR listener question:

Thanks to NOAA's ThreadEx Project (threaded extremes using the Army Signal Corps data), the National Weather Service official climate record for the Twin Cities starts in 1871 for daily precipitation, and 1872 for daily high and low temperatures. My question: how many record daily climate values (high and low temperatures, and precipitation) that still stand today were established during that first year of observation (1871 and 1872), over 140 years ago?


Good question. To the best of my knowledge there are still two daily precipitation records from 1871 (0.85 inches on Jan 23 and 1.28 inches on Apr 19); there are four daily low temperature records from 1872 (-13 F on Nov 27, -27 F on Dec 23, -31 F on Dec 24, and -24 F on Dec 27); and there are two cold maximum daily temperature records from 1872 (-1 F on Nov 28 and -10 on Dec 21). In fact the week leading up to Christmas that year was the coldest in history with a mean daily temperature of -18 degrees F over December 18-24, 1872. So in total there are still 8 daily climate records in the Twin Cities that have survived from 1871-1872.

Twin Cities Almanac for July 13th

The average MSP high temperature for this date is 84 degrees F (plus or minus 8 degrees F standard deviation), while the average low is 64 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for July 13th:

MSP weather records for this date include: highest daily maximum temperature of 105 degrees F in 1936; lowest daily maximum temperature of 65 degrees F in 1975; lowest daily minimum temperature of 50 F in 1926 and 1990; highest daily minimum temperature of 86 F in 1936; and record precipitation of 2.79 inches in 2013.

Average dew point for July 13th is 60 degrees F, with a maximum of 80 degrees F in 1995 and a minimum of 40 degrees F in 1926.

All-time state records for July 13th:

The state record high temperature for this date is 111 degrees F at Minnesota City (Winona County) in 1995. The state record low temperature for this date is 32 degrees F at Sawbill Camp (Cook County) in 1940 and at Brimson (St Louis County) in 1990. State record precipitation for this date is 5.02 inches at Indus (Koochiching County) in 1999 (although 5.85 inches fell at Northfield in 2013 at a CoCoRaHS station); and no snowfall has been reported on this date.

Past Weather Features:

July 13, 1890 brought severe weather to parts of eastern Minnesota. About 4:30 pm an F-3 (winds 158-206 mph) tornado touched down in Anoka County and traveled 10 miles southeast through Ramsey County. It destroyed over 50 cottages on Turtle, Snail, Vadnais, and Gervais Lakes, killing 6 people and injuring 30 others. The same thunderstorm complex destroyed the town of Newport, and downburst winds overturned the excursion boat, Sea Wing, on Lake Pepin, drowning about half of its 200 occupants, the worst boating disaster in state history.

July 13-14, 1919 brought heavy thunderstorms to eastern Minnesota. Maple Plain and Minneapolis reported over 2 inches, while downtown St Paul received over 3 inches. It was the heaviest rain of that summer.

From July 6 to July 14, 1936 eight days were over 100 degrees in the Twin Cities, and the early morning low on the 13th was 86 degrees F, the highest minimum temperature ever measured in the Twin Cites. In fact seven times that month the overnight low did not drop below 80 degrees F.
July 13-14, 1970 brought heavy thunderstorms to southwestern and south-central Minnesota. Lamberton, Minnesota, Tracy, Mankato, New Ulm, and Marshall reported over 2 inches of rainfall, while Worthington and St James reported nearly 3.50 inches. Windom received 5.69 inches and reported street flooding.

About 3:00 pm on the afternoon of July 13, 1974 an F-2 tornado (winds 113-157 mph) traveled 7 miles across Ottertail County and destroyed several trailers and a machine shed near Fergus Falls. Fortunately there were no injuries or deaths attributed to this storm.

Over July 12-14, 1990 a brief cold spell visited northeastern Minnesota. Observers at Brimson, Cotton, Duluth, and Isabella reported temperatures in the 30s F. On the 13th Brimson started out at 32 degrees F and warmed up to 80 degrees F by afternoon.

On July 13, 1995 a Heat Wave brought daytime temperatures of 100 degrees or higher to 25 Minnesota communities. With dewpoints in the 70s F the Heat Index soared and ranged from 105 to 115 degrees F that day. This spell of heat was also the cause of many deaths in the city of Chicago, especially in neighborhoods without air conditioning.


Near normal temperatures over the weekend with a chance for widely scattered showers and thunderstorms. Drier for Monday through Wednesday of next week with temperatures that are slightly cooler than normal. Another chance for showers and thunderstorms by late Wednesday and Thursday.
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