Nicholas’ erratic behavior is making it difficult to forecast

By Jennifer Gray, CNN

As we are now at the official peak of hurricane season, I remind myself that hurricane season is a marathon, not a sprint. It’s a long season of constantly looking at forecasts and being nervous about when the next big storm will show up in forecast models.

I also wanted to update you on where we stand with hurricane season, now that we have officially hit the peak of the season, and it looks like the second half shows no sign of slowing down.

It’s also a reminder that it doesn’t take a “big” storm to have a major impact.

Nicholas could be one of those storms. Just a few weeks ago, the Northeast received extreme rains — and that was just the remnants of Ida.

Nicholas is a tropical storm with the potential to bring catastrophic flooding to parts of the Texas and Louisiana coastlines. You can see from this satellite image, Nicholas’ cloud deck already is over portions of Texas and Louisiana.

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The center of Nicholas keeps moving

When storms such as Nicholas don’t get their act together and become organized, it becomes difficult to find the center of circulation in the storm.

With this storm, it has been even more difficult. The center keeps falling apart and reforming, at times 90 to 100 miles from its last position. This makes forecasting where the storm will make landfall — and where it might do the most damage — all the more difficult.

Earlier this morning, the storm’s center emerged more than 100 miles from its previous location. And again, it seemed with the 11 a.m. ET advisory to be falling apart in one location and reforming in a new location.

“The earlier near-eyewall pattern dissipated a few hours ago, and has been replaced with what appears to be an ongoing reformation of a new center about 90 miles north-northeast of the old center,” said the National Hurricane Center.

Hurricane hunters are currently en route to investigate the storm. But with Nicholas seemingly inching closer to the coast with each new center formation, there will inevitably be an earlier landfall.

Still, there could be a small window of time for Nicholas to strengthen.

“Strengthening is still expected until landfall as Nicholas continues to move over slightly warmer Gulf waters,” said the hurricane center. “It is possible that Nicholas could become a hurricane just before landfall.”

Nicholas is a 60-mph tropical storm and moving to the north at 12 mph. The speed has increased a little since earlier this morning. However, the storm is still expected to move very slowly during the next few days.

This means one thing: FLOODING.

20 inches of rain is not out of the question

“Nicholas is expected to produce storm total rainfall of 8 to 16 inches, with isolated maximum amounts of 20 inches, across portions of the middle and upper Texas coastal areas through the middle of the week,” said the hurricane center.

Yes, you read that correctly: We could see FEET of rain from this storm.

And a lot of that rain could fall in a very, very short period of time. Potentially 3 to 4 inches an hour could fall during the peak of the storm.

This means you should stay hyper-aware in case a flood watch is issued for your area. The duration in which the rain falls is a huge factor in how bad the flooding will be, but there’s a strong possibility that some areas will experience a great deal of rain in a short amount of time, which will lead to flash flooding.

Parts of Louisiana could also see high water. “Across the rest of coastal Texas into southwest Louisiana rainfall of 5 to 10 inches is expected. This rainfall may produce areas of considerable flash and urban flooding, especially in highly urbanized metropolitan areas,” said the hurricane center.

It’s certainly possible for some areas that were impacted by Ida to get additional rain from Nicholas. South-central and southeast Louisiana could pick up as much as 4 to 6 inches of rain during the next three days as Nicholas slowly slides up the Texas coast and moves into Louisiana.

It’s hard to know at this point where the worst of the rain will set up. We know that this area is the highlighted region where the most rain will most likely fall.

Twenty inches of rain could have huge implications, especially if it falls in only a day or two. We saw what happened in New York two weeks ago with 8 inches of rain in less than a day. Of course, NYC and the Texas coastline are not apples and apples.

Now parts of the coast, including Houston suburbs, are at high risk of flooding. This is the same threat level of flooding that was issued to the Northeast ahead of the catastrophic flooding due to Ida’s remnants.

To determine how much rain a certain region can endure, you have to consider many factors. For one, urbanization plays a huge role. If a majority of the rain falls in Houston, we could see more implications than if the water fell along coastal areas.

The topography also plays a role. With the Texas coast being relatively flat, the region can hold more water. But FEET of rain inundating an area means the potential for life-threatening flooding will be real with Nicholas.

Why?

The reason for the flooding potential is that Nicholas is moving so slowly. A slow-moving storm will produce higher amounts of rain. We saw it with Harvey in 2017 over Texas. And the climate crisis has showed us that storms will be slower and wetter in this warmer world we live in.

As of now, this does not look like a Harvey event, but the forecast does show a significant flash flood threat that needs to be taken seriously. Harvey dumped widespread amounts of 20 inches of rain — with isolated amounts of more than 40 inches — across southeast Texas.

Storm surge and tornadoes

In addition to the excessive rainfall, we will see storm surge. Portions of the Texas coastline could see 3 to 5 feet of storm surge. Galveston Bay could get 2 to 4 feet. Because Nicholas is moving so slowly, we could see the storm surge last for several high tide cycles, only making the flooding worse.

Tornadoes will remain a threat during the next few days because of Nicholas. It is very common to see tornadoes with tropical systems. The areas with the greatest threat will be right along the coast from Galveston Bay to Corpus Christi.

Preparing for flash flooding? What to do?

The best way to prepare for a flash flood is know whether you are in a flood zone. You should stay knowledgeable about what rivers and streams are near you and what those flood stages are. More people die in flooding than in tornadoes and hurricanes.

Two out of three people who die in flooding die in their cars. It’s incredibly important not to be on the roads during a flooding event. Most people receive alerts on their phones in the event of a flash flood emergency. Make sure you can get alerts.

• Mobile phone — Wireless emergency alerts are one of the best ways to receive warnings anytime, anyplace. On an IOS device go to settings, then notifications, and scroll to the bottom. Make sure emergency alerts — listed under government alerts — are turned on. If you use a third-party app, be sure the alerts are issued in a timely fashion. Most importantly, have those notifications turned ON.

Water can rise quickly in a flash flood event; make sure that you are not in your car when this happens.

If a flash flood warning is issued for your area, get to higher ground as quickly as possible. Do not wade in floodwater. It could be contaminated or electrically charged. Also, never drive through flooded roads. It only takes 2 feet of water to wash away most cars, including SUVs and pickup trucks.

Where we stand this hurricane season

We are 14 named storms into the season right now, and we still have a little less than half the season to go.

“I do expect the rest of the season to be quite busy,” said Phil Klotzbach, research scientist at Colorado State University.

Forecast models suggest we are headed into a La Niña pattern, which means a more active hurricane season for the Atlantic basin.

“This type of scenario typically enhances conditions for a robust Caribbean low-level gyre that typically spins up late-season storms. We saw this scenario on steroids last year. Let’s hope we don’t have another October-November like we had last year, but I think the large scale should favor another active end to the season,” said Klotzbach.

Just because we have passed the “peak” of hurricane season doesn’t mean that storms will be on the decline. We could see just as strong and impactful storms during the second half of the season.

The hurricane center is also watching two other areas for possible development. An area of low pressure is expected to form north of the southeastern Bahamas this week and move northwest toward the eastern United States. This has a 50% chance of development during the next five days, according to the hurricane center. Areas from the Outer Banks to the mid-Atlantic need to closely monitor this for development.

The other area is a tropical wave off the coast of Africa. It has an 80% chance of development during the next five days as it travels westward over the open tropical Atlantic. This will be something to closely monitor as we get into next week.

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