FAIRWAY, KS (KCTV) – The hottest air so far this summer is headed our way this week. An Excessive Heat Warning goes into effect Wednesday. This is happening as the remnants of Barry are moving away. Tuesday afternoon the center of Barry, marked with an “L” was just south of St. Louis.
Barry gave us a cooler, and at times, cloudy start to the week but that is about to change and in a big way!
Barry will get absorbed into the jet stream and quickly race into the eastern United States. In Barry’s wake, the jet stream takes up a familiar summer-time location over the northern plains.
I’ve plotted the jet stream on the map below. It’s the blue and green contoured area where the strongest winds aloft will be found later this week. This set up often allows a dome of hot air to develop across the central and southern plains.
See the red shaded area on the map below? That’s the area where air is piling up this week.
When air piles up, it sinks. When air sinks, it compresses and warms. Have you ever noticed that when you pile on a lot of blankets, it gets pretty toasty under the bottom blanket? That’s because all those layers are compressing the air and warming it up. But it’s not just the hot air this week, it’s also the humidity.
We’ve got some very juicy air flowing into the mid-west. Dew point values are forecast to be in the mid-70s. Dew points are a better measure of the moisture in the air. Why? Because the higher the dew point, the more humid it feels.
Ever notice that in the Winter the relative humidity can be 90% but it doesn’t feel that humid. That’s because warmer air can hold more moisture than cold air. High heat and high dew points can combine to create dangerous outside conditions during peak heating of the afternoon.
That’s why an Excessive Heat Warning is in effect, starting Wednesday afternoon at 1 p.m. It lasts until 8 p.m. Saturday for all of the pink highlighted counties on the map below.
Just one glance at the map below and you’ll understand why there’s concern over the heat this week. The graphic below is the forecast heat index for Thursday afternoon. Forecast heat indices are expected to be well above 100-degrees over a large part of the nation’s mid-section.
And not just for one day but for several days. We’ve had little bouts of heat this summer but this will likely be the longest and most intense stretch of heat we’ve seen in about a year.
Wow, doesn’t that map look hot? Excessive Heat Warnings are issued when the heat index is expected to range from 105 to 110 degrees during the afternoon and the nighttime temperature is not expected to drop below 75 degrees.
That could be the case in and around Kansas City through the weekend. So here are some things to remember over the next few days.
Remember the heat index is measured in the shade. It can feel a lot hotter in direct sunlight and can have a bigger impact on your body.
Remember high humidity slows evaporation and our bodies work harder to stay cool. But the wind will help this week. We are forecasting gusty southwest winds between Wednesday and Saturday. A breeze helps as it can aid in evaporating sweat off our bodies allowing our internal temperature to continue cooling.
Yes, the heat makes for great pool and lake weather but also remember that even when you are swimming in cooler water, you will be sweating. So it’s important to drink lots of water. Drink about three quarters to 1 quart of water every hour when the heat and humidity are this high.
Also remember to work in frequent breaks from the heat. Hopefully we’ll get a break from the heat in about a week.