Tropical Update: The tropics are beginning to get more active. Watching!

ncwxauthority

August 11, 2026 at 2:20:12 PM

🌀 Tropical Update: Good afternoon, everyone. I'm sure everyone is sick of working on this fine Tuesday, so as you take your scroll break from work, I thought you'd love to read my tropical update. In true fashion as we head toward the start of schools/colleges, the tropics are coming alive, and this year is no different. I am, and forecasters at the National Hurricane Center are monitoring two main areas for potential tropical development in the Atlantic Ocean and two areas in the Pacific Ocean, with one showing a potential threat to Hawaii.

In the Atlantic, we have an area of disturbed weather in the North Atlantic moving away from the United States that has a low chance 20% of some Tropical Development over the next 5-7 days, but does not pose any threat to NC!

Down in the Main Development Region of the Atlantic, we've had several tropical waves that are moving off Africa over the next 5-10 days, and some are trying to show signs of development. There is now a 70% from the National Hurricane Center that a Tropical Depression or Storm will develop in this area. There remains high wind shear and dry air, so it'll face an uphill battle as it moves generally westward across the Atlantic. Since the system has not even developed, let's take models with a grain of salt and not jump to too many conclusions, but the threat to North Carolina at this point is rather low. So there's no reason to worry at this point.

Image 2: Is a graphic I created to give you an idea how long it takes tropical systems to travel across the Atlantic Ocean (NOT A FORECAST), just an example. This location is 10-14 days away, and it may not even survive the trek across. There could be some enhanced moisture to parts of the Caribbean Islands which they very much need.

Over in the Pacific, there is an area of disturbed weather over 1k miles east southeast of the Hawaiian Islands that has a high chance of becoming a Tropical Depression or Storm. Interests in the Hawaiian Islands should closely

monitor the progress of this system.

I'll keep you posted all season long; nothing to worry about right now in NC!

Mountains

110°F

Raleigh area

CADEN NELSON

What Meteorologists are Looking For on Radar During Severe Weather

Caden Nelson

Jun 17

2 min read

We've all experienced it - gathering around the TV as the broadcast meteorologist goes through a list of cities and towns in the path of a tornado-warned storm. But how do meteorologists know when to warn a storm? What are meteorologists looking for?

If you've ever driven past a National Weather Service office, there's likely one thing that stood out - a NEXRAD (Next-Generation Radar) doppler radar.

The NEXRAD Radar at Fort Fix in New Jersey

A Brief History of Weather Radar

Prior to the NEXRAD, the national radar network consisted of WSR-57 (developed in 1957) and WSR-74 (developed in 1974). While helpful at the time, the United States knew it needed an upgrade. Why? Because neither radar allowed meteorologists to see wind speed and wind direction, which is crucial for detecting rotation within storms.

What Makes NEXRAD Different?

NEXRAD came with a number of improvements, including Base Velocity (BV), which shows wind direction. Not only that but it also improved resolution and sensitivity and most importantly, an increased range.

Scientific American's graphic below shows exactly how doppler weather radar works:

So, back to our scenario - sitting in the living room, around the TV, watching the tornado-warned storm heading towards you. How do meteorologists know that there's rotation?

On a velocity radar scan (bottom left), colors represent wind motion:

Green shades = wind moving toward the radar
Red shades = wind moving away from the radar

When these two strong signals appear right next to each other, it indicates rotation within the storm. This is what meteorologists refer to as a velocity couplet, and it can be a strong sign that a tornado is forming—or already occurring.

Another critical radar product is Correlation Coefficient (CC) - the image on the right.

This tool helps meteorologists determine what types of objects are being picked up by the radar.

High values (reds/oranges/yellows): uniform precipitation like rain or hail
Lower values (blues/greens): mixed or non-uniform objects

When a distinct “drop” or pocket of low correlation appears inside a storm, it can indicate debris being lofted into the air—such as:

roofing material
siding
trees
or other ground-level debris

This is often referred to as a debris signature, and it can be strong evidence that a tornado is on the ground.

So do we always know when a tornado is on the ground? Not always. Radar gives meteorologists powerful clues, but it is not perfect. Some tornadoes are short-lived, rain-wrapped, or occur in areas where radar resolution is limited. However, when strong rotation and a debris signature appear together, confidence increases significantly that a tornado is ongoing.

The bottom line: if a Tornado Warning is issued, take cover immediately.