Weather blog: Why so hot?

Published: Jul. 13, 2017 at 11:06 AM MDT
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To say it’s been hot over the last several days may be a bit of an understatement. I used to run in the middle of the afternoon, but have since found that running early morning is a much wiser idea. In case you’re curious, we have only seen one day so far this month where the temperature was less than 90 degrees. That day was actually Tuesday. As referenced in the image above the average high temperature so far this month is right around 95 degrees. The million-dollar question then becomes; why are we so hot?

The answer to that is actually quite simple. Our weather pattern is to blame. Actually, our weather pattern is to blame for more than just the increased temperatures. It’s also responsible for the increased cloud cover, the increased dew points, and the convective showers and thunderstorms some folks have seen in the evening almost like clockwork.

Now, let’s dive into that weather pattern a bit. When I forecast I take a top down approach. By that I mean, I begin each day looking at the highest levels of the atmosphere. In this case, right around the level commercial airplanes fly. That’s where the upper level jet is located. Sometimes the upper level jet brings cold Arctic air from the North, zonal flow that brings warm, but tolerable temperatures, and sometimes such as this month, the upper level jet brings very warm southwesterly air. The upper level jet has been coupled with an area of high pressure sitting over the Southwest, which is only aiding in bringing more warm air into southern Idaho. Southwest flow in the upper levels also brings in a lot of Pacific moisture. That means at the surface there’s a lot of very warm and very moist air. Now imagine you have a parcel of air of any size you choose. That air parcel rises and as it raises it cools. Eventually this parcel of air is going to match the temperature of the environment around it. This is known as the Lifted Condensation Level. In short, when a parcel of air reaches this level it condenses all the moisture out and a cloud forms. From here, the cloud has the ability to build and instability grows. This is why we see the afternoon and evening showers, because instability is at its highest due to the hot temperatures, and convection is at its greatest.

That incredibly scientific paragraph is a short version (yes, I said short) of our recent weather pattern and its affects on us here in southern Idaho. Enjoy the summertime heat because winter will be here again before you know it!