Why Summer Storms Tend to Linger Longer

You are not imagining it if you feel like the latest waves of storms have lingered longer. Storms tend to move more slowly during the summer months. But why is that? Here is a deeper look into the science behind the crawling storms that push through the U.S. during the late spring and summer months.

Jet Stream's Influence on Movement of Storms

Nearly everyone has been caught up in a typical summer storm that seems to hover over a small area for an extended period of time. It does not take long for an inch or two of rain to pile up when these storms train over a specific region and deliver repeated downpours. The slow-moving characteristics of this time of the year can be blamed on a sluggish jet stream.

The jet stream tends to be more active during the winter and fall months, sending the energy moving along at a faster rate. As a result, the jet stream is more productive and influential beginning in the fall and lasting through the early spring months. Conversely, this same flow of air that hovers about 30,000 feet high slows down during the summer months.

The narrow ribbon of air flow and winds retreats to the north during the summer, pushing it up near the border of the U.S. and Canada. This movement to the north naturally chips away at its ability to drive weather patterns across most of the U.S. The wind speeds circulating in the jet stream also slow down as the summer progresses, further mitigating its impacts on the weather across the Lower 48.

There are other factors that contribute to the slower-moving storms as the temperatures heat up. Cold fronts pushing across the northern third of the country are also more likely to become lodged in one place. This stalling out can be blamed on the lessening ability of the jet stream to push the fronts along.

The stalling out of the cold fronts means that thunderstorms are more likely to behave in a sluggish manner. The end result is a proliferation of storms that get stuck over one particular area, dumping greater amounts of rainfall over shorter periods of time.

Although the moisture can be good news for areas struggling with drought during the dry summer months, too much precipitation too quickly can also raise the risk of flash flooding dangers. The repeated downpours can linger for days until the responsible cold front eventually breaks apart.

Impact of Pop-Up Storms and Tropical Weather

What forecasters refer to as pop-up storms also tend to happen more frequently during the summer months. These types of storms happen when high humidity levels pair with the heat from the intense sunshine, creating billowing clouds that produce storms that seemingly come out of nowhere. This type of pop-up storm activity is the most common in the southern U.S. when humidity levels tend to run the highest.

It does not take long for the random storms to dump flooding rainfall. The absence of the jet stream movement in the South means that the storms are more likely to train over a smaller area of land.

The uptick of tropical weather events as the summer progresses also contributes to the greater chance of storms that stall out. The lack of influence of the jet stream means that tropical weather events are more likely to slow their forward speed and unleash massive amounts of moisture over the impacted area.

Difference Between Summer and Winter Jet Stream

Although the summer jet stream is less of a driver of overall weather patterns, the opposite is true of this stream during the winter months. The jet stream is more influential during the colder months of the year because there is a greater temperature gradient throughout the U.S. The higher gradient means that storms are able to move along at a faster clip from the west to the east, using the jet stream as a conduit for energy.

The winter jet stream is also wavier. This contrasts with a flatter flow of winds during the summer. Lastly, the jet stream also moves from north to south to a greater degree during the winter, rather than remaining stagnant over the northern edge of the U.S. in the hotter months. As such, weather makers are able to move more freely across the country during the winter.

The takeaway from all of this information is that it should not be surprising when storms slow down and stall out in the months ahead. Knowing that this is a possibility can help you to plan accordingly and be aware of the higher risk of flash flooding.

Weather changes fast — help your community stay prepared. Share this story with friends, family, or your group chat.