Posted at 2:43 PM on July 6, 2012
by Mark Seeley
Using defining characteristics of consecutive 90 F days, plus a minimum duration of 8 days I have ranked the historical summer Heat Waves in the Twin Cities based on mean temperature over their duration. I included June 28th of the current period (though the high was 88 degrees F). The list below defines 14 such period in our climate records, with the current period ranking 4th. Let's hope it is the only one of the summer!
Historical Heat Waves in Minneapolis/St Paul which lasted at least 8 days and delivered daytime highs of 90 degrees F or greater. Ranked by Mean Temperature Value for their duration.
7/5/1936 to 7/18/1936 14 days 88.6 degrees F
7/21/1941 to 7/28/1941 8 days 85.3 degrees F
7/28/1955 to 8/4/1955 8 days 84.7 degrees F
6/27/2012 to 7/6/2012 10 days 84.3 degrees F
7/23/2006 to 7/31/2006 9 days 84.2 degrees F
7/5/1937 to 7/13/1937 9 days 83.9 degrees F
7/2/1948 to 7/12/1948 11 days 83.6 degrees F
7/9/2005 to 7/17/2005 9 days 83.6 degrees F
7/25/1935 to 8/1/1935 8 days 83.6 degrees F
6/29/1949 to 7/7/1949 9 days 83.5 degrees F
7/12/1932 to 7/20/1932 9 days 83.3 degrees F
7/26/1988 to 8/3/1988 9 days 82.9 degrees F
6/16/1995 to 6/23/1995 8 days 79.9 degrees F
8/3/1896 to 8/10/1896 8 days 79.6 degrees F
Current period ranks 4th
I have a thermometer outside the west metro weather lab that is 4 feet off the ground, over grass, in direct sunshine. It read 131 degrees (not the heat index) at 3:30 p.m. Meanwhile, many thermometers in the metro area, properly shaded, were pushing the mercury to 100 degrees or more. This is serious heat, not often experienced in our neck of the woods. The dewpoints in the lower 70s make conditions almost unbearable.
In northern Minnesota, cooler air has already brought relief. A generous rain also fell in the lake country region in the past 18 hours.
Rainfall totaling up to 3 inches likely accumulated around the Brainerd Lakes area.
Estimated rainfall from the Duluth Doppler radar. Source: NOAA/Weather underground.
This satellite image clearly identifies the different air masses. At 3 p.m. CDT it was 64 degrees in Duluth, Staples and Longville. Minneapolis, St. Paul and Winona sat at 100 degrees. It was 101 at Flying Cloud Airport in Eden Prairie.
NOAA visible satellite image at 245 p.m. CDT. Source: College of Dupage.
Thunderstorms may ignite shortly near Granite Falls. The Storm Prediction Center has a risk for severe weather for later this afternoon and tonight.
This outlook defines the threat for large hail and damaging winds. There is a potential for isolated tonadoes.
Once we get this cool front to sag south of Minnesota overnight, we will see more comfortable temperatures for Saturday and Sunday afternoon. I'm thinking this front does not have a lot of giddyup. We could experience highs in the mid 80s on Sunday afternoon in southern Minnesota.
The NAM forecast paints temperatures in the 80s for 1 p.m. CDT on Sunday. The winds will be light as well on Sunday afternoon.
At 4 p.m. CDT it is 101 degrees at the Minneapolis-St. Paul International Airport and 102 degrees in Winona. The record for today in the Twin Cities is 104 set in one hot summer of 1936.