As is almost always the case, I read a number of complaints on a certain social media network about the lack of thunderstorms yesterday. First, let’s do a little recap of the severe storms that didn’t show up and why that was the case.
Thunderstorms need three key ingredients to form – moisture, unstable air, and lift. If you remember, I mentioned in yesterday’s update that NWS Pittsburgh launched a special balloon and instrument package in order to sample the atmosphere ahead of the storms. They did and the data showed a warm layer of air in the mid-levels overhead. This warm zone prevented clouds from building to heights needed for thunderstorms to develop. The result, no lift. Generally, the taller a storm can get, the stronger it can become. A layer that prevents storms from growing tall enough to become a thunderstorm is commonly called a ‘cap’.
In addition to the cap overhead, wind shear was just not adequate. As a result of these two factors, thunderstorms had an unfavorable environment in which to form and grow.
A severe watch does not guarantee thunderstorms. A watch only tells us that conditions are favorable in the watch area for thunderstorms to occur. As it turned out, those favorable conditions didn’t pan out as expected and conditions slowly degraded as the afternoon progressed after the watch was issued.
While we can often know ahead of time that atmospheric conditions could be favorable for severe weather to develop, our atmosphere is a multi-layer cake that’s in constant motion. Some layers travel in different directions than other layers in a dynamic process known as fluid dynamics. It doesn’t always behave in a manner we expect.
End of today’s weather lesson.