Have you ever wondered what the local weather report means when it says isolated or scattered thunderstorms?
These terms can make it confusing to know if you should cancel your outdoor activities or not.
We’ve got everything you need to know about isolated vs. scattered thunderstorms. And you’ll be happy to know that isolated and scattered thunderstorms do not affect a whole area. So not all residents will experience the storm.
Isolated vs Scattered Thunderstorms
If you watch the local weather forecast, you’ll often see the terms isolated and scattered thunderstorms in the reports. Meteorologists and weather devices use the terms to describe the extent of thunderstorm activity in a given area.
Both types of storms have a smaller coverage footprint than organized lines of storms.
The main difference between the 2 types of thunderstorms is the storm’s range of coverage. Isolated thunderstorms only have a small scope, while scattered storms cover more expansive areas.
They do not depend on the severity, duration, or extremity of accidents in thunderstorms. The primary factor to consider is the range of coverage.
Which Are More Dangerous?
Because of the difference in coverage, scattered storms can also be more dangerous. Its thunderstorm duration is longer than an isolated thunderstorm.
Both are caused by a cumulonimbus cloud, heavy rain, lightning, strong winds, and sometimes hail. The storm forms when the warm air mixes with moisture, causing it to rise and then fall.
The probability of a thunderstorm occurring is higher during the summer and spring months. It most likely arrives during the evening or afternoon.
These are when the cold westerly winds move over moist, warm air.
In the tropics, storms result from the northeast trade winds, the southeast trades, and the intertropical convergence zone. Thunderstorms are more frequent, contributing to the movement of heat to the higher latitudes.
What Do Isolated Thunderstorms Mean?
An isolated storm means that the storm’s eye focuses on a single coverage. Only about 30% or less of the forecast area can encounter storm activity at a period. But it has a ‘supercell’ thunderstorm classification.
Short Coverage and Unpredictable
Unlike scattered thunderstorms, this thunderstorm type is also challenging to predict.
That’s why the number of people experiencing ailments and illnesses also increases in an isolated thunderstorm.
There is also an inconsistent presence of thunderstorms because of the aerial coverage. It might be sunny in one area but stormy in a location that’s only 20 miles away.
According to meteorologist forecasts, the precipitation probability in one area may only range from one to three. Expect this number of storms for the rest of the day.
Where Isolated Thunderstorms Occur
Isolated thunderstorms are more likely to happen if the winds are light and stable regardless of their height. It also occurs more frequently in areas with plenty of moisture in the lower part of the atmosphere, about 10,000 meters.
Another term for these storms is an air mass or local thunderstorm. Although we can’t fully explain the duration of isolated and scattered flurries, isolated showers are typically short-lived and vertical.
How Isolated Thunderstorms Form
Isolated thunderstorms develop through an upward motion of the air. This cell formation is unsteady and comes from plenty of rising eddies.
Then, precipitation and cloud grow until a downdraft occurs. Such rainfall, snow, or hail occurs due to excessive accumulation.
The updrafts and downdrafts become close, and the downdraft disperses throughout the cell.
That’s why isolated thunderstorms are not super intense. They also have at least one convective cell in the different evolution phases.
Signs of Isolated Thunderstorm
Some signs of an isolated thunderstorm are:
- High probability of precipitation.
- Hail storms.
- Strong winds.
- Large and dark cumulonimbus clouds.
- Lightning activity.
- Possible tornadoes.
Is an Isolated Thunderstorm Bad?
Most of the time, isolated thunderstorms are not a cause of concern. Since its coverage of rain showers is only 10%-30%, there’s a 70%-90% chance you’ll stay dry.
Even though the precipitation events are challenging to predict, you are unlikely to get caught in the storm. Just stay informed about forecast discussions.
You don’t need to cancel your outdoor activity. If you need to cancel it because your area is affected, there’s a high chance that you’ll resume it right away.
In some cases, isolated thunderstorms can feature more severe storms than scattered thunderstorms. The conditions occur so quickly that a tornadic activity may occur. Especially in places such as Tornado Alley.
What Does Scattered Thunderstorms Mean?
If you look at a scattered thunderstorm in a radar image, you will see several storms covering a vast area. The range of coverage is almost twice as broad as isolated thunderstorms, at 30%-50%.
Affects a Bigger Area
Scattered thunderstorms are usually more severe than isolated thunderstorms. That’s because it affects a more significant piece of land. It also has a longer duration, making it a bigger cause of concern.
However, they are not severe because of the storm’s intensity. Scattered thunderstorms are short-lived and belong to a multicell cluster thunderstorm classification.
Unlike a supercell, multicell thunderstorm classification is not super strong.
Affected areas are more likely to experience multiple rounds of storms during the day. You may experience precipitation from thunderstorms for a few minutes, then the sun appears. Later on, a severe thunderstorm may occur again.
Lightning Activity
You can also experience more extreme lightning during a scattered thunderstorm.
Based on weather observations, lightning strikes are about ten times on the ground. It also only has gentle hazards.
Stay indoors when you observe lightning in the distance. It typically strikes several miles away from the storm’s core.
Cancel Your Plans
Even if you experience weaker showers, scattered thunderstorms can be dangerous because of the large area they cover. Reschedule your plans to avoid getting struck by lightning.
Stay prepared for unpredictable weather changes. The condition may instantly change from sunny to lightning scenarios.
Signs of Scattered Thunderstorms
Here are some signs of a scattered thunderstorm:
- Weak tornadoes.
- Flash flooding.
- Medium-sized hail.
A clear sign that scattered showers are about to occur is when the days are cloudier than usual. Even if rain forecasts state that the thunderstorm risk is low, the sky’s instability will lead to sprinkles and showers.
How Scattered Thunderstorms Form
A scattered storm has many updrafts and downdrafts close to each other. They occur in many stages and clusters of cells.
One cell is more dominant in one cluster until another cell repeats it. Thunderstorms may also form in an organized line for a continuous gust.
How Long Do Scattered Thunderstorms Last?
There’s no real way to predict if scattered thunderstorms last long or not. What meteorologists know is that it will be spotty. Since it’s an on-and-off scenario, each storm may last more or less ten minutes.
What are Widespread Thunderstorms?
The word widespread means “to scatter over a substantial extent.” Widespread storms and showers mean that 60% of the area or more will experience thunderstorms. Here, the coverage across the region is more extensive than scattered thunderstorms.
It’s advisable to cancel outdoor activities and stay indoors during this time.
In Conclusion
The primary difference between an isolated vs. scattered thunderstorm is their range of coverage. An isolated thunderstorm covers a portion of a region, while scattered thunderstorms involve different areas.
These categorical terms do not describe the severity and duration of the storm. In some cases, isolated thunderstorms can be stronger even if they only cover one area.
Got more questions about thunderstorms? Share them in the comments, and we’ll feed your curiosity! And if you’re looking to monitor your weather conditions, consider getting a home weather station!
