Both meteorology and history are worrying forecasters about a late-September hurricane

AccuWeather

AccuWeather forecasters are predicting a high chance of development for a tropical system in the Gulf of Mexico between Sept. 23 and 25. But what are the chances it will make landfall in the U.S.?

Transcript

00:00I want to bring in AccuWeather Chief Meteorologist Jonathan Porter and John, you know, we begin

00:04with this, the decision was made yesterday that we were going to upgrade our risk for

00:11development from a low to immediate.

00:14We made that change in the early morning before AccuWeather early started and then later on

00:19in the morning, we went to a high risk.

00:22As far as I can tell, we are the only known weather source that are going this high for

00:29the risk for development next week.

00:31That's right, we are and we're concerned, we're doing that purposely because we're concerned

00:36that a tropical storm can form in this vicinity and move toward the United States and we're

00:42not going to have many, many days to track it.

00:45Alright, last night you and I were chatting about, you know what, when it comes to forecasting

00:51long range, you have the computer guidance, that's one tool, but the other thing we like

00:55to look at is what does history say and we have such a large database of tropical storms

01:02and hurricanes across the Atlantic Basin.

01:05So what we did is, where we think we're going to get that developing in the Northwest Caribbean,

01:12within 100 nautical miles, what does history tell us that storms that move in that area,

01:19where do they go and you can see all of the results here.

01:23A lot of storms and again, this is for the month of September.

01:26That's right, the thrust of those storms goes into the Gulf of Mexico, the majority, the

01:31wide majority of those storms go into the Gulf and many of them from Louisiana toward

01:35Florida.

01:36So this is one of the tools that we can look at in terms of helping us to hone on those

01:41risk areas and just to be clear, each one of these lines is a tropical storm or hurricane

01:47that approached the coast all the way back to 1850, so there's a long database of those

01:52tropical storms and hurricanes.

01:54Ari and I crunched the numbers this morning, this is what we came up with.

01:57So there it is, where this system is going to form, the majority of the storms, tropical

02:04storms or hurricanes, went to the central Gulf Coast states.

02:07You can see Florida's not too far behind the peninsula, but as you get toward Texas, there

02:13is less.

02:14Keep in mind, this is the entire month of September, John.

02:17I suspect that number in Texas would be lower if we would just combine the storms to late

02:22September.

02:23I think that would be the case as well, and it's also important to point out this is the

02:26historical risk of a landfall.

02:29This is not the risk that we're assessing with this particular situation, but it gives

02:33us a very good indication of what history tells us and climatology tells us.

02:38And notice that central Gulf Coast lights up right away with 38% of the storms going

02:44in that direction, but then also the Florida peninsula, 17%.

02:48This is why for several days here, ahead of all other sources, we have been stressing

02:53that this area between Louisiana and Florida is of greatest concern to us for the storm

02:59that hasn't even developed yet.

03:00It won't develop until later this weekend or early next week down in the Northwest Caribbean

03:05Sea and then move northward.

03:06And also, Bernie, you can see this is why we have not been able to all clear anyone

03:10yet because there still can be some risk even back to Texas.

03:13All right, that's history.

03:15Let's now go to meteorology.

03:16What does meteorology say?

03:18There are two differences.

03:19We showed you what the history tells us, intensification likely, Louisiana to Florida.

03:23John, let's talk about the meteorology, what we are seeing right now in the weather and

03:29as we look forward in the next week.

03:32Several factors that, from a meteorology perspective, we're looking at, that very warm water, all

03:36of them point toward a strengthening storm, and that's what the concern is.

03:41With plenty of moisture and lower wind shear, we're going to talk about those particular

03:46factors.

03:48Let's talk about the warm water first, John.

03:49It's not just warm water here, and this is plenty warm enough.

03:52I mean, we're talking water temperatures in the middle to upper 80s.

03:56These are running four to six, even a little bit higher, degrees above historic average

04:02across much of the Gulf, but it's not right at the surface.

04:05This is what you're looking at to see surface temperature.

04:08It's through a depth of the ocean, and that's the big concern.

04:11That's what we're looking at here.

04:12This is what we call ocean heat content, or also known as fuel in our mind, in terms

04:17of the types of things that can be rocket fuel for a developing tropical storm or hurricane.

04:22Look at this red line, Bernie.

04:24This is all-time records for ocean heat content in the Gulf of Mexico.

04:29That's not good news.

04:31History tells us that these storms like to go toward Florida and Louisiana.

04:35Let's talk about what the pattern looks like next week, middle part of the week.

04:41The trough or dip in the jet stream that starts or kickstarts this process leaves,

04:46but there's another one coming behind it.

04:48It sure is, and this is going to be really the key to the movement of the storm.

04:53Is this dip in the jet stream a little bit further to the south?

04:56Is it a little bit quicker?

04:57That all has ramifications to where this developing storm may want to track.

05:03At this point, we continue to be concerned, as we mentioned, most concerned about Louisiana

05:09toward Florida, with the dip in the jet stream being a little bit faster and a little bit

05:13further east.

05:14It would guide the storm in that direction.

05:16If the jet stream dip is a little bit weaker, Bernie, that's where we start talking about

05:20more concerns for parts of the Texas coastline or even down in Mexico.

05:25Still all options are open at this particular time.

05:28One final word, John.

05:29Why are we giving all of this?

05:31We're trying to give people as much notice as possible.

05:34There's a reason for this.

05:35You may not have a lot of time to prepare for landfall once this forms.

05:41That's an important point, and we want people to be prepared, not scared.

05:45That's very important.

05:46Additional, providing you with what we know that's in our AccuWeather DNA so that you

05:51can make the best decisions and certainly stay with us.

05:54Frequent updates on the AccuWeather network, AccuWeather.com, and the AccuWeather app.

05:59I think as we, Bernie, you and I were talking about, this is an important point to be flexible.

06:03People may need to alter their plans.

06:05This can be a serious hurricane threat into next week.

06:09AccuWeather Chief Meteorologist Jonathan Porter.

06:11John, thanks for joining us here this morning on AccuWeather Early.

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