Eric Berger

June 20, 2023 Outlook: Extreme sea temperatures are fueling Bret and a second Atlantic system

The National Hurricane Center began issuing advisories for Tropical Storm Bret on Monday, and we’re also tracking a second system not far behind that likely will also become a named storm. Both of these systems have formed in the “main development region” of the Atlantic where tropical systems often begin their lifetimes. However, the season for storm formation in the main development region typically does not kick off until August.

So what’s happening out there? Well, it’s blazing hot.

Graphic showing temperature anomalies in the main development region. (Ben Noll)

Ben Noll, a New Zealand meteorologist, noted on Monday that sea surface temperatures in the main development region are the warmest they’ve been on record for June. In fact, the seas are as warm now as they typically are in late August or September, when the Atlantic hurricane starts to peak. That’s one reason why we’re seeing a spate of early season activity.

A second chart from Ben is equally concerning, as it shows temperatures in this region presently exceeding those of the 2005 and 2010 Atlantic hurricane seasons, both of which produced frenetic activity. The 2005 season remains the most active year in my lifetime, and Gulf Coast residents will doubtlessly remember Katrina, Rita, and Wilma all reaching Category 5 status in the Gulf of Mexico.

Well, that’s concerning. (Ben Noll)

Warm seas are not the only factor in storm formation, of course. This year, with El Niño in the Pacific, we can have some hope that wind shear will counteract the formation of storms. But worryingly, so far, warm seas appear to be winning out against El Niño. I have to say that I am starting to get mildly concerned about what is to come this year, particularly in August and September.

One-sentence summary

We’re tracking Tropical Storm Brett as well as Invest 93L, which has been given an 80 percent chance of developing this week into a depression or named storms in the coming days.

Brett is being followed by a system that would be named Cindy, if it develops. (National Hurricane Center)

Happening now: The stage is set for Bret, with a possible encore

Here’s what we know about the two tropical systems out there.

Tropical Storm Bret

First of all, with apologies to fans of George Brett, this system has just one “t.” After forming on Monday the storm has changed little in intensity overnight, with sustained winds of 40 mph. This is likely due to some moderate wind shear nearby. Not enough to break the storm apart, but enough to keep its organization at bay.

The system has about three days to get its act together before shear is expected to increase, in which case Bret should start to weaken. At present the National Hurricane Center brings Bret to hurricane strength briefly, before winding it back down on Thursday night as it approaches the Lesser Antilles islands in the Caribbean Sea.

Bret is bound for the Caribbean Sea. (National Hurricane Center)

No one wants to see a tropical storm headed their way, and Bret is something that people in the Caribbean Islands, including Puerto Rico, the Dominican Republic, and Cuba will want to keep an eye on. Damaging winds and heavy rainfall are definitely possible with Bret later this week or weekend, although I don’t think we’re looking at a situation where this storm really blows up. My biggest concern is flooding, but it’s not really possible to say where the heaviest rain will occur. We should have a better handle on the overall threat tomorrow morning.

Invest 93L

Much like its predecessor, Bret, how well this tropical system gets organized is tied up with where it goes, with a better organized disturbance likely turning northwest before the Caribbean and a less organized one likely following 92L to the west and into the islands. For now the most likely outcome, I believe, is that this system turns north before reaching the Caribbean Sea. That would be best for all concerned, except maybe for the fish.

The medium range (days 6-10): And then there were three?

As Matt noted on Monday, there are some signs in the models that yet another disturbance will emerge off Africa soon, and that this may be something that could develop over the weekend or next week. However the models don’t appear too excited about this system becoming a big deal, likely due to a fairly uninviting environment overall for development. Certainly at The Eyewall we’re rooting for shear to have its day.

Fantasyland (beyond day 10): Possibly calmer to end June

After this present spate of activity, the overall tropics may turn a bit quieter to end the month and start July.

Hopefully?

That Atlantic system is nearing tropical depression strength

Good afternoon. We hope everyone is having a great Father’s Day—here in Houston I am enjoying some time with the family but this face-melting heat and humidity is something else. The situation is little different out across the Atlantic tropics, where sea surface temperatures are at or near record levels for this time of year. And lo and behold, the warm tropics are producing uncharacteristically robust activity for mid-June. Hence this post on a holiday weekend.

An area of interest, known for now as Invest 92L, has continued to show signs of organization today as thunderstorm activity increases and it passes through an area of relatively low wind shear. As a result, the National Hurricane Center now gives the system a 90 percent chance of becoming a tropical depression or tropical storm in the next two days. In all likelihood, we’re looking at Tropical Storm Bret by early next week. In other words, I’d bet on Bret. Sorry for the dad joke, but today is Father’s Day you know.

Not Tropical Storm Bret. Yet. (NOAA/The Eyewall)

This tropical system should continue to have a reasonably favorable environment for strengthening into the middle part of next week as it continues to track westward across the tropical Atlantic, toward the Windward Islands. After that? Well, if the storm continues trucking westward it will eventually face more hostile conditions. This means that a tropical storm could move into the Eastern Caribbean Sea by Thursday or so, but then likely weaken. The other scenario is that the storm begins to turn more northerly before entering the Caribbean Sea. Along this path the tropical system would find more favorable conditions, but should spin harmlessly out in the ocean.

The bottom line is that if you’re in (or traveling to) the Windward or Leeward Islands—basically from the Virgin Islands all the way south to Barbados—it’s worth keeping an eye on this system. I don’t think anything too troublesome is coming, but the Atlantic is very warm so it’s worth monitoring. As for other parts of the Atlantic basin, including the United States, this probably is not anything more than a curiosity. We’ll have bigger fish to fry later this season, no doubt.

June 14, 2023 Outlook: Some things to watch, but nothing to get worked up about

Good morning. Eric here. Before we jump into the forecast I want to provide a couple of programming notes. First of all, I’ll be filling in for Matt most of the time on Wednesdays, so you can look forward to this (or skip hump days, accordingly) for the rest of the season.

Additionally, be sure and check back on The Eyewall later this morning (9:30 am CT or 14:30 UTC) for an in-depth post by Matt about hurricane activity and the Gulf of Mexico. We’ve seen a spate of major storms in the last six years, particularly with rapidly intensifying and extremely damaging hurricanes. Matt dives into the latest research and speaks with hurricane scientists about whether this is really a trend, and what it means for coastal residents. It’s an excellent, informative long read.

One sentence summary

Conditions continue to look fairly benign across the Atlantic, but in about a week we may have an item or two to watch.

Happening now

All remains quiet this morning with no areas highlighted in the Atlantic basin by the National Hurricane Center over the next seven days.

The medium range (days 6-10): Perking up a little bit

The global models are continuing to drop hints about the potential development of a tropical wave about one week from now in the Atlantic Ocean, to the east of the Windward Islands. There is now some support for this in both the European and Canadian global models, but neither really develop it significantly. Wind shear will likely play a role in hampering its development.

The Canadian model is one of several that are hinting at a tropical system near the Windward Islands next week. (Weather Bell)

These tropical waves will become more potent later in the season, when they spin off of Africa more frequently, and the combination of lower wind shear and peaking sea surface temperatures aid their development. For this wave, since it is June, we just really don’t have any significant concerns. We’re only mentioning it now because there is just not a whole lot else to talk about.

The other area to watch is the southern Caribbean Sea, where low pressure may congeal into something approaching a tropical system. This could happen during the period of about a week from now. This may eventually push some storminess northward toward Cuba or Florida, but at this time I don’t anticipate anything too organized. We will, of course, keep an eye on all of this and more, updating you as things change.

The European ensemble forecast places a nearly 50 percent likelihood on development of a tropical depression in the Caribbean Sea next week. (Weather Bell)

Fantasyland (beyond day 10): A little noisy

Overall, this is just an extension of the medium-range outlook. The GFS model, for a time, gets pretty excited about the system in the southern Caribbean Sea, but since this is a distinct outlier at this time—and entirely consistent with that model’s predilection to take even a whiff of low pressure and go hog wild—it is not something worth getting worked up about.

Matt will be back with you on Thursday!

June 7, 2023 Outlook: Europe names a windstorm, and Fantasyland comes alive

Good morning. Eric here, and I’m thrilled to extend my welcome to readers of The Eyewall. Matt has been doing a fantastic job so far, and the response we’ve received to the site has been great. Thank you for reading, and telling your friends and families in other states vulnerable to tropical weather. In today’s post we’ll talk about the lack of activity right now, and the GFS model’s propensity to develop spurious storms. Matt also continues his look at what to expect from the 2023 hurricane season, overall.

One-sentence summary

No meaningful tropical development is expected over the next week or so, though a system near the Azores Islands has a very low chance to briefly become something before the weekend.

“Oscar” is swirling off the coast of Africa and Spain. (EUMETSAT)

Happening now

Beyond the Azores system, nothing is happening now. Just a word on that storm, however, which is interesting to US readers in the sense that it allows us to talk about something relatively new. For the last eight years several European countries have started naming “windstorms,” and like we have a hurricane season they have a windstorm season. In this case, the Azores storm is named “Oscar,” and it could have impacts on the Canary Islands later this week. Some weather warnings are in place.

The medium range (days 6-10): Still quiet

If we look at the 10-day forecasts from the major global models, there is still really nothing to shake a stick at. This is perfectly normal for the early part of June.

Fantasyland (beyond day 10): No changes in thinking

There is life in fantasyland, however. In about 11 days from now, the GFS model develops a tropical low in the Caribbean Sea, and then drags a fairly potent looking storm into the Gulf of Mexico by about day 14 or 15. There are two reasons why this system is likely spurious. First of all, we commonly see these kinds of far-out tropical systems in the GFS model at this time of year. And secondly, when we look for support for this idea in the ensembles, it’s just not there.

Oh look, the GFS has manufactured a hurricane at <checks notes> day 15 of its current run. (Weather Bell)

Nevertheless, I would expect to see some chatter about this possibility over the next few days, as excitable observers look at the GFS model and say, “Oh look, a hurricane is going to hit Texas on June 23!” I mean, anything is possible, right? But it’s not something I’d lose any sleep over. We’re certain to face much more credible threats later this summer, so save your angst for something that’s more likely to be real.

The 2023 seasonal outlook Part 2: El Niño

When you hear the phrase “El Niño,” we would assume that most Gen X’ers, Xennials, and geriatric millennials think of Chris Farley and his 1997 take on the weather event on Saturday Night Live. Truthfully, that clip has aged pretty well. They got the gist of things correct.

What is El Niño? By definition, it is a periodic warming of the water around the Equator in the Pacific Ocean, west of Peru to the central Pacific, near the Dateline. In reality, it’s a pretty complicated phenomenon involving both the ocean and the atmosphere, and because of where it unfolds, it sends ripple effects around the world in the form of changes to weather patterns. You can read more about the “what” behind El Niño here, but we’re going to focus on how it impacts hurricane season.

How does El Niño impact the tropical Atlantic? What tends to happen during El Niño events is an uptick in tropical activity in the Pacific Ocean. With more warm water available in the tropics, with more thunderstorm activity spreading east from the Western Pacific, and with generally lower wind shear, the Pacific tends to be the action center during hurricane seasons with El Niño.

During El Niño events, there is usually more wind shear over the Atlantic basin due to the reshuffling of the upper level pattern as warm water expands east across the Pacific Ocean. Hurricanes do not like wind shear. (NOAA)

Because the structure of the upper atmospheric pattern changes when that happens, a situation develops where there is generally a mean ridge of high pressure (calm conditions) over the subtropical Pacific. With the jet stream, what goes up usually must come down, and that typically produces a mean trough (unsettled conditions) over the Caribbean and southwest Atlantic. Hurricanes like calm conditions in the upper atmosphere. That means reduced wind shear. So during an El Niño, the Pacific side usually has less wind shear than usual, while the Atlantic side usually has more of it, limiting the amount of hurricanes that form.

As a “for instance,” if we took the 10 strongest Oceanic Niño Index values (the statistically strongest summertime El Niño events) for the 3-month period of July through September going back to 1950, those hurricane seasons averaged 9 storms, 4 hurricanes, and 1 major hurricane, well shy of the 30 year average of 14, 7, and 3 respectively. Of course, within those 10 “quiet seasons” we had a handful of memorable storms: Betsy in 1965, Agnes in 1972, Joaquin in 2015, Audrey in 1957, Flora in 1963, Charlie in 1951, and Isidore and Lili in 2002. It only takes one! But the takeaway here is that El Niño does tend to favor less busy Atlantic seasons.

What’s El Niño doing right now? Well, we’re technically not yet in El Niño. There are certain criteria that need to be met over the course a few months. However, we’re all but officially there. The Australian Bureau of Meteorology this week declared an El Niño Alert, giving at least a 70 percent chance that it will happen. NOAA has us in an El Niño watch. A look at a sea surface temperature anomaly map clearly shows that the Pacific is warm.

If you look across the Equator at the Pacific Ocean west of South America you can see above normal water temperatures dominating the region, indicating development of an El Niño is likely underway. (NOAA)

Most of the global oceans are warm right now, but the El Niño certainly stands out. You can see this in an even more telling manner by looking under the surface of the ocean across the Equatorial Pacific.

Click to enlarge this animation from April through late last week, which is looking at water temperature anomalies in the Equatorial Pacific from 80°W longitude, across the Dateline to 120°E longitude, or basically from South America to Oceania. The surface is the top of the graph, and the bottom of the graph is 450 meters (~1,500 feet) below. That’s a lot of warm water. (NOAA)

There is nothing but warmer than normal water from the surface down about 700 feet across the Equatorial Pacific. Basically, El Niño is just about here, and it would be safe to assume that we will have one in place for the majority of hurricane season. Thus, when making the seasonal hurricane outlook, the first key point for 2023 is El Niño, so this should likely act against a busy season.

But these things are complicated, and while El Niño certainly gives us optimism that the season may be a bit more subdued than normal, that map of global water temperature anomalies above shows a big problem in the Atlantic. We’ll discuss that in more detail tomorrow.