All Weather News

Glorious Heat Relief!

31 Aug 2013, 2:48 pm

It is the Labor Day Weekend, the unofficial end to Summer, and its only fitting that we end a Summertime heat wave around the same time frame.  All across the upper midwest, it has been an oppressively hot week, with temperatures breaking records, a lot of sticky air and very little wind.  The heat wave has crested, the temperatures have started to come down and by Labor Day, there will be a big sigh of relief from many folks across the area as drier, and mild air comes in from Canada.  At least you can turn your A/C off and open up the windows.  I’m sure you won’t mind not getting that electric bill when it comes if you live in places like Minneapolis, Des Moines, Madison, Kansas City, Pierre, Bismarck, St. Louis and Omaha, to name a few.

In Madison and Rapid City, temps were into the low 90s but felt hotter than that when you factored in the humidity.  The dewpoints will go down from the 70s/60s to the 50s, which is considered very comfortable.

For some places, the heat was so high that the thermometers were rising to the point they were breaking records.  The city of Des Moines, hitting a temperature of 104°, is rarely this hot, this late in the season.  The record for the day was 99° set back in 1898.  This is an exert from the NWS Des Moines office about that high temperature.

“The high of 104 degrees on August 30, 2013, was the warmest reading ever recorded in Des Moines this late in the year.  The previous latest date of a 104 degree reading or higher was on August 26, 1983.
This was also the latest first 100+ degree day in Des Moines on record (the city had not reached 100 degrees all year before that day). The previous record was August 24, 2003.”

Here is hot the heat wave has been in Des Moines, IA.  Temps hit nearly the 100° mark on multiple occasions.

In the Twin Cities area in Minnesota, temps were in the mid 90s (but felt into the low 100s)  for several days before finally going down into the mid 80s by Friday.  With the dewpoints up into mid 60s, the air still had that muggy feel in it, but it was certainly better than what it had been before.

Between today (Saturday) and Labor Day, the jet stream will start to dip southward across the Great Lakes and a slow moving cold front will move through the midwest, eventually into the Ohio River Valley.  It will squeeze out all that moisture, and usher in some milder air in from Canada.

The water vapor imagery shows where there is moist and dry air in the atmosphere.  The drier air is shaded black to brown while the most moist air is white to green.  That swirl in the image where the “L” is is where the area of low pressure is and it is on the move across the southern Canada/northern US area.

There is plenty of warm and humid air, which is just fuel to the fire for storms to form, and all it needs is a trigger such as the approaching cold front.  There is a slight risk for severe weather from Minnesota, down to around the Missouri/Kansas area with a heightened chance of seeing some larger hail and isolated tornadoes in central and northern portions of Minnesota.  Here is the link to the Storm Prediction Center’s page of where the risk zone is, as well as who can see what (in terms of hail, wind, tornadoes).

The very warm and muggy conditions that have been displaced from the northern plains, have moved down into the central plains, where states like Missouri and Kansas have several counties in a Heat Advisory through the weekend.  The heat index values will be into the upper 100s and make it hard to do strenuous activity outside for a prolonged period of time.  Its best to drink plenty of water and to take it easy during days like that.

The Minneapolis area will see temps go down from the 90s to the 70s in 48 hours and then slowly rise to moderately warmer temps as the shortened work week progresses.

In St. Louis, the highs today are getting into the low 100s and will still be running above normal by tomorrow.  But on Labor Day, its back to normal for the daytime highs and they will stay around that area for the rest of the week.

We hope you have an enjoyable holiday weekend and can get out and about.  But if you are in an area that is to be threatened by storms, you can be “weather ready” by having a NOAA weather radio handy with you so you can be alerted.  They are inexpensive and can keep you up to date with the latest info from the National Weather Service.

Meteorologist Addison Green (Twitter: @agreenWNTV)

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