Urgent Warning: Extremely Severe Storms Can Arrive With Little Notice — Here’s What You Need to Know

The images show scenes that look almost unreal: palm trees bending dramatically under powerful winds, dark storm clouds covering an entire city, and a massive rotating cloud formation stretching across the horizon.

When skies become this dark and winds suddenly intensify, it can be a sign that dangerous weather is approaching.

But dramatic photographs alone cannot confirm exactly where a storm occurred, how severe it was, or when the images were taken. Weather conditions can change rapidly, and old photographs are also frequently reposted online with new captions.

Still, the scenes highlight an important issue: severe thunderstorms and tropical storms can produce dangerous conditions within a very short period of time.

Why Does the Sky Become So Dark Before a Severe Storm?

One of the most recognizable signs of an approaching storm is a rapidly darkening sky.

Large thunderstorms can develop enormous cloud systems called cumulonimbus clouds. These clouds can extend many kilometers vertically and contain powerful updrafts and downdrafts.

When a large storm cloud moves between the observer and the sun, sunlight can be dramatically reduced.

The result can be a sky that suddenly looks almost black.

The darker appearance doesn't necessarily mean that the storm itself is unusual. It often reflects the enormous thickness and density of the cloud system.

The Powerful Winds Can Be Dangerous

The photograph of palm trees bending almost horizontally demonstrates how strong winds can affect vegetation.

Severe thunderstorms can produce damaging straight-line winds, while tropical cyclones can generate sustained winds and powerful gusts over large areas.

Strong winds can:

• Break tree branches
• Knock down trees
• Damage roofs
• Destroy signs
• Move outdoor furniture
• Damage vehicles
• Bring down power lines
• Make driving extremely dangerous

Even if there is no tornado, powerful winds can cause significant damage.

This is why people should take official severe-weather warnings seriously.

Heavy Rain Can Create Another Major Hazard

Wind isn't the only danger associated with severe storms.

Some storms can release enormous quantities of rain over a relatively short period.

When rainfall exceeds the ability of the ground and drainage systems to absorb or carry away the water, flash flooding can occur.

Flash floods can develop quickly, particularly in:

• Low-lying areas
• Urban neighborhoods
• Areas near rivers
• Mountainous regions
• Places with poor drainage

Floodwater can also be deceptively dangerous.

A road that appears to have only a few centimeters of water may actually contain much deeper or faster-moving water farther ahead.

Never Underestimate Floodwater

One of the most important storm-safety rules is simple:

Never drive through flooded roads when you cannot determine the depth and condition of the water.

Moving water can push vehicles off the road.

Floodwater can also conceal:

• Open drains
• Damaged roads
• Debris
• Fallen power lines
• Deep holes
• Broken pavement

Even large vehicles can lose traction in moving water.

If authorities close a road because of flooding, the safest decision is to find an alternative route rather than attempting to cross it.

Lightning Is Another Serious Threat

Severe thunderstorms frequently contain lightning.

Lightning can strike outside the area where heavy rain is falling, meaning people should not assume they are safe simply because the storm appears to be several kilometers away.

If you can hear thunder, lightning is close enough to pose a risk.