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Heat Abates, But Southern Minnesota Continues Wet July

After a week of temperatures that averaged 5-10 degrees warmer than normal with dew points in the 70s F (even some 80°F dew points), temperatures fell back to a few degrees cooler than normal much of this week, with much low dew points and humidity. It was a sharp contrast to the near record-setting Heat Index Values that occurred last Friday (July 19th) when many portions of the state experienced Heat Index Values of 110°F or greater.

Also for at least a few days, there was some relief from the heavy rainfalls of this month. Believe it or not, some portions of Dodge, Goodhue, and Blue Earth Counties have reported over 11 inches of rain this month. At least 24 other southern Minnesota climate stations have reported over 8 inches of rainfall so far this month, and so far this month 35 climate stations in the state network have reported setting or tying at least one daily rainfall record.

You can read more about this change in the weather from the Minnesota State Climatology Office.

Weekly Weather Potpourri:

Western Europe’s 2nd major Heat Wave of the summer settled in this week, setting widespread temperature records. The three-day Heat Wave produced some remarkable readings: 109°F in Paris, France; 106°F at Bordeaux, France; 107°F at Deelen, in the Netherlands; 107°F at Lingen, Germany; and 104°F at Kleine Brogel, Belgium. Madrid, Spain reported 7 consecutive days of daytime temperature close to 100°F. The temperature hit 100°F in Cambridge, England for only the second time in history, and Edinburgh, Scotland recorded its hottest day ever with a reading of 89 degrees F. Trains in the United Kingdom were asked to slow down to avoid derailments due to buckled tracks. A climatology institute in Potsdam, Germany, said Europe's five hottest summers since 1500 were all recorded in the 21st Century.

The Weather Underground web site provides a good overview of the heat, dryness, and wildfires that are occurring across many western states this week. Some residents near Idaho Falls, Idaho were evacuated because of a spreading fire near there. Thankfully, a better weather pattern is expected to emerge next week and assist firefighters in controlling these wildfires.

A new study from the University of Bern shows that large climate fluctuations of the past were not really global, but varied from region to region. "It's true that during the Little Ice Age it was generally colder across the whole world," explains Raphael Neukom, "but not everywhere at the same time. What we didn't know until now is that not only average global temperatures in the 20th century are higher than ever before in at least 2,000 years, but also that a warming period is now affecting the whole planet at the same time for the first time. You can read more in the journal Nature.

In this week’s AGU-EOS bulletin there is an article about how NOAA scientists have been working to improve the resolution of their climate trend analysis over both land areas and the oceans. The latest version of NOAA’s Global Surface Temperature Dataset improves coverage over land and sea and improves the treatment of historical changes in observational practices.

MPR listener question:

At my garden weather station in Bloomington this week, the relative humidity fell to just 35 percent. We opened the windows of the house to let the cool, dry air in and it felt great. Made us wonder what has been the lowest relative humidity historically during the month of July?

Answer:

Naturally, the lowest July relative humidity readings in the Twin Cities climate record are associated with drought years. In both 1934 and 1936 the relative humidity in July fell to just 19 percent. More recently in the drought years of 1988 and 2012, the July relative humidity fell to 21-22 percent. I might add that relative humidity values as low as the single digits have been observed in other months of the year, most notably October.

Twin Cities Almanac for July 26th:

The average MSP high temperature for this date is 83 degrees F (plus or minus 7 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 26th:

MSP weather records for this date include: highest daily maximum temperature of 100 degrees F in 1955; lowest daily maximum temperature of 68 degrees F in 1972; lowest daily minimum temperature is 45 degrees F in 1962; highest daily minimum temperature of 76 degrees F in 1931; record precipitation of 2.44 inches in 1990; and no snow has fallen on this date.

Average dew point for July 26th is 60 degrees F, with a maximum of 77 degrees F in 2003 and a minimum of 37 degrees F in 1974.

All-time state records for July 26th:

The state record high temperature for this date is 107 degrees F at Beardsley (Big Stone County) in 1931. The state record low temperature for this date is 27 degrees F at Kelliher (Beltrami County) in 2001. State record precipitation for this date is 5.24 inches at Rochester (Olmsted County) in 1949; and no snowfall has occurred on this date.

Past Weather Features:

The hottest July 26th in state history was in 1931, when over 35 climate stations reported daytime highs of 100°F or greater. The nighttime low at Wheaton (Traverse County) never dipped below 81 degrees F.

A series of strong thunderstorms dropped 2.5 to 5.5 inches of rain across portions of southern Minnesota over July 26-27, 1968. Some large hail was also reported. Many roads and highways closed due to flash flooding.

It was a frosty morning for campers in northern Minnesota on July 26, 1980. Many areas of Beltrami, Roseau, St Louis, Koochiching, and Lake of the Woods Counties reported minimum temperatures from the upper 20s F to the low 30s F. The daytime temperature only climbed to 69°F at Cass Lake.

Outlook:

A generally sunny Saturday will give way to increasing cloudiness on Sunday and a chance for showers and thunderstorms, especially in southern counties. A cooler and drier weather pattern will prevail for next Monday through Thursday, with temperatures a few degrees below normal. Temperatures will start climbing to a few degrees above normal by next weekend, with an increased chance for showers.













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