Heat wave builds across Central U.S.

By: Angela Fritz , 10:44 PM GMT on July 16, 2011

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Extreme heat is building across the Central U.S., and it doesn't look like it will let up for the region until Thursday or Friday. Excessive heat warnings, heat advisories, and excessive heat watches blanket the central U.S. from Texas north to Minnesota.

Temperatures will top 100°F in some locations, and heat indices could surpass 115°F. Expect that overnight lows might not get below 80°F—values that are 15 to 20 degrees above normal for much of the Upper Midwest. The heat is expected to remain in place for most of the week, but will begin to shift eastward by Thursday or Friday.

A strong ridge of high pressure is in place across most of the U.S., allowing high temperatures to build. Combine that ridge with the prolonged, intense drought across the southern tier, and you have a recipe for an extreme July heat wave.

In the Upper Midwest, enough moisture will be present to make the heat unbearable. The "heat index" is often referred to as the "feels-like" temperature—how hot it feels to your skin. When temperatures soar, humidity can exacerbate the heat. The Midwest has had just enough rain in the past couple of weeks to make the air more humid than it is down south, which is why the heat index will be so high in this region. The air moisture is also caused by agriculture. We often see high humidity where lots of corn is grown, especially Iowa.

Forecasters and public health officials alike are asking people to take precautions over the next week. Drink more water than you usually would, especially if you exercise or work outdoors. Avoid alcohol. Stay inside in air-conditioned buildings, and check on family and neighbors. Don't run the air conditioning too cool as this could lead to widespread power outages if everyone does the same. The demand on power plants will already be exceptionally high.

Local Forecasts:

Dallas, Texas
Amarillo, Texas
Oklahoma City, Oklahoma
Kansas City, Missouri
St. Louis, Missouri
Omaha, Nebraska
Des Moines, Iowa
Rapid City, South Dakota
Minneapolis, Minnesota
Fargo, North Dakota

You can find your own local forecast by entering your city or zip code in the search bar at the top of the page.




Current U.S. Heat Index


This colored contour map shows current heat index. Heat index is the apparent temperature considering both the temperature and relative humidity. The key below the image shows the corresponding heat index for each color.



Current U.S. Temperature


This colored contour map shows current temperatures. The key below the image shows the corresponding temperature value for each color.



Current U.S. Relative Humidity


This colored contour map shows current relative humidity. Relative humidity is the ratio of water vapor contained in the air to the maximum amount of water vapor that can be contained in the air at the current temperature. The key below the image shows the corresponding relative humidity for each color.

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7. Zachrey
12:41 AM GMT on July 19, 2011
In Minneapolis, I saw that on Sunday July 17, they had a dew point of 81F !!!

That's insane! Where else do you get a dew point OVER 80F?!

So if you set you air conditioner, if you're lucky enough to have one, to say, 78F, you'll get frosted glass!

It's almost to point that if you want to cool off, you can go to Brownsville Texas.
Member Since: November 7, 2003 Posts: 0 Comments: 4
3. Gerbick
5:18 PM GMT on July 17, 2011
Here in south Louisiana it is so very hot and humid. It feels like I am in an oven when I walk outside. Stay hydrated!
Member Since: April 29, 2010 Posts: 0 Comments: 2
2. mnsky
9:57 AM GMT on July 17, 2011
WOW~
Member Since: June 28, 2010 Posts: 1 Comments: 26

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About angelafritz

Atmospheric Scientist here at Weather Underground, with serious nerd love for tropical cyclones and climate change. Twitter: @WunderAngela

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