Thanks for stopping by the WeatherWatch 12 Blog!
Tonight we are going to talk about the first heatwave of the season that arrived Monday.
At 6pm Monday, the observation at Milwaukee’s General Mitchell Field hit 94 degrees! This is a new record high for the date and is just the start of 3 days in a row of 90s.
A Heat Advisory will go into effect at noon on Tuesday because not only will we have temps in the 90s, but dew points are in the 60s to near 70 and that is border line tropical!
The combination of the heat and humidity creates a heat index, this is where it actually feels hotter than the actual temperature and in some ways is the opposite of wind chill in the winter time.
Basically, your body tries to cool by perspiring and the perspiration then evaporates, and cools your body by taking heat from your skin as energy to evaporate the sweat. This is called evaporative cooling and is the reason why you feel cold when you step out of a pool or the shower.
When moisture content in the air is really high, this process does not happen as easily, and your body then can not cool efficiently…and you begin to feel hotter.
These conditions are especially dangerous for pets, little children, and the elderly. Be sure to drink plenty of fluids if out enduring the heat the next couple days.
Here’s why we are going to be so hot.
A surface low pressure center is tracking to our west and helping to steer our wind flow not only at the surface but aloft as well from south and southwest. The air we are experiencing has Gulf of Mexico origins! So aside from the lack of palm trees, it literally will feel like we in Florida!
When forecasting temperatures, especially on sunny and when there is some wind, look at how warm the temperatures are up about 5,000 feet. This is because the heating of the Earth’s surface causes turbulence and can actually mix down the air from aloft.
When this happens, the air from aloft is compressed (because the pressure is greater at the surface) and will warm via adiabatic compression! Sort of like air will heat up when you pump up a bike tire. The laws of physics say that if you compress an air parcel, it has to then warm, if air expands (rises) it cools.
Here’s a forecast of temperatures at about 5,000 feet Tuesday afternoon.
Notice the darker red shades indicating +22 to +23 degrees C. This would translate to 93-95 degreef F at the surface! That is why the forecast is calling for low to mid 90s at least!
Areas Waukesha west will be in the mid/upper 90s!
Stay safe in the heat…and find the A/C!