Nature Lets Out the Dogs, Dewpoints, and Downdrafts

This is vintage dog day weather. Notice Tiger on the right is licking his chops and BJ on the left looks like he is ready to pounce on the treats I was holding up. Who let the dogs out? Nature! You can walk to your mailbox out there this morning and get a good workout in. What happened to our comfortable weekend? The dewpoints are what happened. This is the true measure of humidity. When your dewpoints jump from the 50s to the 70s the atmosphere can hold twice as much water vapor. Notice the dewpoints above will be an unbearable 72 today after only being close to 56 on Saturday. The more water vapor in the air, the more uncomfortable it is, especially as temperatures climb into the 80s. Anytime your dewpoint reaches near 70 or above that is considered oppressive.

Why does it feel more like Florida, Mississippi, or Lousiana out there? You can blame this Bermuda high pressure off the East Coast you see below. When you walk outside it does feel like you are wrestling an alligator down in Bayou country.The clock-wise flow around this high pressure brings plenty of moisture or maritime tropical air our way. It is our heat pump this time of year and we really feel it as it expands and grows stronger in July and August. So remember to blame the Bermuda high and not me.

I am an avid runner and I do tell runners to run mainly before 9 a.m. in this weather and after 8 p.m. at night. The heat really takes a toll on your body and it really is not worth taking a chance in that steambath outside. Your body simply cannot effectively cool itself down and if you push yourself too hard it can be really serious. You have to be weatherwise this time of year. Remember the most weather-related fatalities every year comes from not flooding or tornadoes, but hot weather.

Here is what you need to know.When you combine the heat and humidity there is what is called the heat index. When the heat index temperature is 94 or above like we will see today that when you have to exercise caution. Keep in mind this is a shade temperature. To find your runner's or workout temperature this time of year, take the actual temperature and add at least 15 degrees. Now if it becomes humid or If the dewpoints are 70 or above add 25 degrees. If it is a cloudy day in the summer with lower humidity you still add 10 degrees. So for instance today's forecast high is 87.When you use my formula and add 25 degrees with 70+ dewpoints it comes out to 112 degrees. This is your runner's temperature today at 4 p.m. Even this morning by 10 a.m. with temperatures near 80 the runner's temperature would still be 100 to 105. So remember the early bird gets the worm. Overdoing it in this weather is just not smart, even if you are Hercules. I do practice what I preach and over the weekend even with the comfortable humidity I did my 11.1 mile long run on the treadmill inside at the gym. The runner's temperature on Sunday afternoon when I was ready to conquer the 231 hill was in the middle to upper 90s so I took my workout inside. It was tougher than running outside, but well worth it.

Now you are not totally covered just yet in being weatherwise today. When you combine this heat and humidity with a cold front this time of year it can get even more interesting. Your typical late day storms will have a little more lift thanks to the cold front and you can get some pretty vicious wind gusts in a hurry. Today the Storm Prediction Center has us in a slight risk for severe weather. You can see our area outlined in yellow above. Last night there were several reports of 60 to 70 mph wind gusts in Iowa, Minnesota, and Wisconsin. This same set-up is in place here at home today and tonight. Even though we have light lower level and upper level winds you can still get some severe weather because some of these thunderstorms can build up to over 10 miles high in the sky. Here is a picture below for you to visualize this.

For every updraft that builds into a thunderstorm in as little as 20 minutes, you have a downdraft that develops when raindrops become heavy enough to fall to the ground. This downdraft can pick up quite a bit of momentum when it starts several miles high in the sky. Some cloud tops grow to well over 50,000 feet or more than 10 miles high in the sky. What a drop! Imagine what happens when a thunderstorm collapses. You can get what is called a microburst or straightline winds that can cause damage in a hurry. So today we will keep our guard up for not only lightning and heavy rain like we saw on Monday morning but some possible damaging wind gusts with those towering cumulonimbus clouds.

I will check back with you during the day as things get more interesting. For now though our weather blog song of the day none other than....I will let you guess before you click on it below. Bermuda high....Baha.....