Excessive heat warning: Rare 80-degree dew points again this weekend?
Oppressive tropical air mass returns with a weekend thunder threat
Get ready for another free sauna Minnesota.
Another hot front blows in on southerly winds Friday. This one may not be quite as hot as last weekend’s heatwave that drove heat index values to 113 in Orono and 116 in St. Peter. But heat index values will top 100 degrees again.
The National Oceanic and Atmospheric Administration’s North American Mesoscale model drives heat index values over 100 degrees again Friday afternoon across much of Minnesota.
The Twin Cities National Weather Service office has issued yet another excessive heat warning for the Twin Cities area Friday.
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Including the cities of Minneapolis, Blaine, St Paul, Stillwater, Chanhassen, Chaska, Victoria, Shakopee, and Hastings
237 PM CDT Thu Jul 23 2020 ...EXCESSIVE HEAT WARNING IN EFFECT FROM NOON TO 9 PM CDT FRIDAY...
* WHAT...Dangerously hot conditions with heat index values up to 101 expected.
* WHERE...Hennepin, Anoka, Ramsey, Washington, Carver, Scott and Dakota Counties.
* WHEN...From noon to 9 PM CDT Friday.
* IMPACTS...Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.
Tropical moisture surge
NOAA’s Global Forecast System model did a pretty good job of gauging high dew point values last weekend. The GFS shows the tropical moisture pump right over Minnesota again this weekend.
Check out the plume of high dew points in the upper 70s to near 80 degrees Friday through Sunday.
Rare 80-degree dew points
Last weekend marks the second consecutive year we’ve recorded 80-degree dew points in the Twin Cities
Looking at the records I believe this is the first time on record we’ve logged ultra sweaty 80-degree dew points in consecutive years.
Since 1945 the Twin Cities has recorded only about 22 hours of 80-degree dew points.
80-degree dew points have occurred only four years since 2003.
Two of those years are 2019 and 2020.
The highest dew point recorded in the Twin Cities is 82 degrees on July 19, 2011.
Here are some more sultry 80-degree dew points facts from the Minnesota DNR Climate Working Group. (Data below through 2018)
80 degree dew point temperatures are rare in the Twin Cities historical record. Since 1945, there have been only twenty-eight hours of 80 degree dew points recorded. Ten of those twenty hours came in a ten hour period on July 12 and 13, 1995. 8 hours are from July 17-19, 2011. The highest dew point temperature ever recorded in the Twin Cities was 82 degrees at 3pm and 4pm July 19, 2011. This broke the old record of 81 degrees at 11am on July 30, 1999.
Maximum Observed Dew Point Temperatures for the Twin Cities in Recent Years
2003 77 degrees F
2004 75 degrees F
2005 81 degrees F
2006 76 degrees F
2007 78 degrees F
2008 73 degrees F
2009 75 degrees F
2010 79 degrees F
2011 82 degrees F
2012 77 degrees F
2013 77 degrees F
2014 76 degrees F
2015 76 degrees F
2016 77 degrees F
2017 74 degrees F
2018 78 degrees F
Stay cool, Minnesota.