Why Friday’s Storms May Be Different From Our Typical Summer Thunderstorms

Friday is shaping up to be one of the more active weather days of the week across Rowan County, with showers and thunderstorms becoming increasingly likely during the afternoon and continuing into Friday night.

But there is something worth watching beyond simply the higher rain chances.

The thunderstorms that develop late this week may have a little more organization than the typical summertime storms we frequently see across Rowan County.

Typical Summer Thunderstorms

During much of the summer, thunderstorms across our area are what meteorologists often call “pulse” thunderstorms.

These storms generally develop when strong afternoon heating combines with plenty of moisture and atmospheric instability. A storm can quickly grow, produce torrential rain, frequent lightning and occasionally damaging wind gusts before weakening.

Individual storms usually do not last particularly long.

Wind through different levels of the atmosphere is often relatively weak during these situations. Without stronger winds aloft to help organize thunderstorms, storms tend to develop, intensify and collapse relatively close to where they formed.

That doesn't mean they can't become dangerous. Even an ordinary summertime thunderstorm can produce damaging winds, flash flooding and dangerous lightning.

Friday's setup, however, could be somewhat different.

An Approaching Cold Front Changes the Environment

A cold front will be approaching the Carolinas late this week.

Ahead of the front, warm and humid air will remain in place across the region. At the same time, winds several thousand feet above the ground are expected to strengthen.

That combination could create more wind shear than we typically see during an ordinary summer afternoon.

Wind shear describes changes in wind speed and/or direction with height.

When sufficient instability and wind shear overlap, thunderstorms can sometimes become better organized and survive longer than the short-lived pulse storms common during the summer.

That is one reason I'll be paying particularly close attention to Friday.

Does This Mean Severe Weather Is Expected?

Not necessarily.

There remains uncertainty regarding exactly where the approaching front will be located, when individual disturbances will move through and how much instability will be available when thunderstorms develop.

Those details matter considerably when determining whether storms simply produce heavy rain and lightning or become capable of producing damaging winds.

At this point, the important message isn't that severe weather will occur.

It's that the environment could be more supportive of organized thunderstorms than what we've experienced during many of our recent summertime storm days.

That makes Friday a day worth monitoring as the forecast becomes clearer.

Heavy Rain May Be Another Concern

Severe weather isn't the only thing I'll be watching.

The atmosphere will contain plenty of moisture, and multiple opportunities for showers and thunderstorms are expected beginning Thursday night and continuing through Friday night.

That means thunderstorms could produce periods of very heavy rainfall.

Rainfall totals can also vary dramatically over relatively short distances during thunderstorms. One portion of Rowan County could receive substantial rainfall while another location several miles away receives considerably less.

Any areas repeatedly affected by thunderstorms would have the greatest potential for localized flooding or standing water.

The Timeline for Rowan County

Wednesday: Sunny and quiet with a high near 92°.

Thursday: Sunny and hot with a high near 94°. The heat index could reach around 101°.

Thursday Night: Showers and thunderstorms become likely. Rain chance increases to 60%.

Friday: Showers and thunderstorms become increasingly likely, particularly during the afternoon. Rain chance is around 60% with a high near 87°.

Friday Night: The highest rain chances arrive, with showers and thunderstorms expected and an 80% chance of precipitation.

Conditions begin improving during the weekend, with highs falling into the mid to upper 80s.

What I'll Be Watching

Over the next 24 to 48 hours, I'll be watching several pieces of the forecast closely:

• The timing and location of the approaching cold front
• How unstable the atmosphere becomes Friday
• The amount of wind shear available to organize thunderstorms
• Whether storms arrive in separate rounds or develop more continuously
• The potential for locally heavy rainfall
• Whether the environment becomes supportive of damaging wind gusts

Small changes in any of these ingredients could make a significant difference in what ultimately happens across Rowan County.

Bottom Line

Friday doesn't necessarily look like a classic widespread severe-weather event at this point.

However, it also may not be a typical afternoon of scattered, short-lived summertime thunderstorms.

An approaching front and stronger winds aloft could provide thunderstorms with more organization than we've seen on many recent summer afternoons. Combined with plenty of atmospheric moisture, that could bring periods of heavy rain and potentially a few stronger storms.

I'll continue monitoring the setup closely as newer forecast data arrives.

For now, enjoy Wednesday's sunshine — because the weather across Rowan County becomes considerably more active as we approach Friday.