Matt Lanza

June 22, 2023 Outlook: Bret prepares for its finale, as the Atlantic stays busy

Tropical Storm Bret is a feisty fellow this morning. It’s about as strong as you can get for a tropical storm before becoming a hurricane. Again, keep in mind that these 70 mph winds are in a small area, not over the entirety of the storm. Hazards such as heavy rain and rough surf will be bigger issues for most of the impacted islands. The good news is that Bret will likely peak in intensity soon before beginning a weakening trend leading to its demise this weekend. Behind Bret, Invest 93L was upgraded to Tropical Depression 4 overnight. It is currently no threat to land.

One-sentence summary

While the Atlantic is bustling with action, the main item to watch is Tropical Storm Bret which will impact the Lesser Antilles with heavy rain, rough seas, and gusty winds today before exiting into the Caribbean and dissipating this weekend.

Tropical Storm Bret won’t win any awards for appearance, but it is trying its hardest to fight off the shear that is inhibiting its organization. (Tropical Tidbits)

Happening now: An August-like Atlantic with TS Bret and TD 4

It’s not often we have two Atlantic storms in June, let alone simultaneous ones, but these are not normal times. Here’s the latest.

TS Bret

Per the National Hurricane Center (NHC) discussion this morning, there were some pretty healthy winds measured overnight in Bret, but they were pretty isolated. Bret is trying to form an eye, but because of shear, that eye feature is displaced east of the surface center. In plain language: Bret is trying hard to fight the shear but it can only do so much. Here is a more annotated look at Bret’s structure this morning.

Tropical Storm Bret is clearly battling shear as it struggles to organize with a low-level center displaced from a mid-level eye feature, as well as raggedness that allows you to “see” the shear. (Tropical Tidbits)

Anyway, the NHC has set the intensity to 70 mph, which again is in a small area. Bret’s biggest impacts to the islands will be via heavy rain and rough seas.

Bret continues to move due west and will pass through the central islands of the Lesser Antilles tonight before dissipating in the Caribbean this weekend. (NOAA)

As of the 5 AM AST advisory:

Tropical Storm Warning (TS conditions likely within 36 hours): St. Lucia, Martinique, Dominica
Hurricane Watch (Hurricane conditions possible within 48 hours): St. Lucia
Tropical Storm Watch (TS conditions possible within 48 hours): Barbados, St. Vincent and the Grenadines

Expect Bret to pass near or make landfall on St. Lucia tonight. In terms of wind, the strongest winds will be along and north of where the center tracks, so St. Lucia and Martinique are likely to see the most gusty conditions and the best chance at sustained tropical storm force winds. The higher terrain of some of these islands will be most exposed to strong winds. Given Bret’s size, tropical storm force winds and gusts could extend from Barbados and St. Vincent north to Dominica. Most places will not see the 70 mph winds, however.

Rough seas will be the most widespread concern. They will continue to build today, with 8 to 11 foot seas expected as the storm approaches and passes in much of the central part of the island chain.

Rain totals will vary, but as much as 6 to 10 inches is possible, especially across the higher terrain of St. Lucia and St. Vincent. Generally 3 to 6 inches surrounds that. Flash flooding will be possible. (Weathernerds.org)

Rainfall may be the most serious concern with as much as 6 to 10 inches of rain, especially at higher terrain. The most likely islands to experience those higher end totals would be St. Lucia and St. Vincent. But I would not be shocked to see some higher end totals on Dominica, Barbados, or Martinique also. In general, 3 to 6 inches of rain will fall, but totals will ultimately vary.

Why are we confident that Bret will dissipate in the Caribbean? It will run into a face-ripping amount of wind shear. That’s never good for tropical systems, and Bret will be the next in a long line of storms to enter the Caribbean and not survive the trip.

Bret will run into a potent amount of wind shear head on in the Caribbean, which should essentially rip it to shreds. (Tropical Tidbits)

So to summarize: We are mainly watching rough seas and heavy rain with Bret from Dominica south to Grenada, although a few areas will see some considerable winds, as Bret is a strong tropical storm.

Tropical Depression 4

Looking east of Bret, we have TD 4. This system does not look especially well-organized this morning, but it may do just enough in the next day or two to attain tropical storm status. The next name is Cindy.

TD 4 is a little one, also fighting off wind shear. It may strengthen to Tropical Storm Cindy over the next day or two. (Weathernerds.org)

The forecast for TD 4 is pretty straightforward. It will be more apt to turn northwest into a weakness between high pressure systems in the Atlantic, which should allow it to run head on into wind shear by Sunday or Monday.

Tropical Depression 4 is expected to become TS Cindy, but it will work northwest into shear and eventually dissipate early next week. (NOAA)

Whatever the case, this system is currently no real threat to land.

The medium range (days 6-10): Beginning to settle down a bit

There is another wave trailing TD 4, but as of right now support for that to develop seems to have dropped off some. So at this point, we don’t expect anything meaningful in days six through ten.

Fantasyland (beyond day 10): Nothing of note

There is nothing of note out in the long-range. Hopefully after TD 4 (or Cindy) we get a couple weeks of quiet.

Don’t bet against Bret yet; 65 mph tropical storm heads toward the Lesser Antilles

Tropical Storm Bret has had a good day for itself, strengthening a bit and taking on a more aesthetically pleasing look on satellite.

The sun sets on Bret on Wednesday evening. Bret is a formidable tropical storm with 65 mph winds. (Tropical Tidbits)

Bret has some good thunderstorms near its center, but it is still clearly fighting some shear. Most of the forecast has not changed for that reason, so we will take a quick look at what to expect in the islands over the next few days.

One-sentence summary

Bret is a moderate to strong tropical storm that will bring waves, some gusty winds, and locally heavy rain to central portions of the Lesser Antilles tomorrow and Friday.

Bret’s impacts

Wind shear is expected to keep Bret from further intensifying much. Yes, there is a chance that Bret could become a top-end tropical storm or category one hurricane briefly tonight or tomorrow. But given the environment around the storm, this is not the most likely scenario. Bret will maintain a due west or west-northwest course, which brings it on track to enter the Caribbean probably near Barbados or St. Lucia. Since Bret is a rather large storm (tropical storm force winds extend out 105 miles from the center), impacts will be felt far from Bret’s center.

Bret is still expected to plow west across the islands in the vicinity of Barbados, St. Lucia, or Martinique, with impacts felt a couple islands away on either side of those goalposts. (NOAA)

As of early Wednesday evening, here’s a rundown of watches and warnings:

Tropical Storm Warning (TS conditions likely within 36 hours): St. Lucia, Martinique
Tropical Storm Watch (TS conditions possible within 48 hours): Barbados, Dominica, and St. Vincent and the Grenadines

The strongest winds will probably be on the north side of the storm, so places like Barbados, St. Lucia, Martinique, and Dominica will likely see the strongest gusts. While there could be some locally strong winds south of there, Bret will likely be a bit lopsided. Stronger winds may impact the Windward Islands from St. Vincent and the Grenadines south to Grenada on the backside of the storm Friday into early Saturday. Overall, while wind impacts are something to prepare for in the islands, they are not considered too serious at this point.

Some fairly substantial swells will be possible on the coast of the central and southern islands. Waves may be as high as 8 to 12 feet per forecasts from the Barbados Meteorological Services. This will lead to erosion, rip currents, and dangerous surf.

Rainfall will also be an issue as Bret pushes through. Thankfully, it continues to move at a healthy clip, so that limits just how much rain may fall, but that does not mean it won’t come with some issues. Roughly 3 to 6 inches will be possible, especially along and north of the track. Isolated amounts of up to 7 or 8 inches are certainly possible.

Updated forecast rain totals from the ECMWF model show a band of 4 to 6 inches from Barbados through St. Lucia and St. Vincent. Isolated higher amounts will be possible, with a general 1 to 3 inches on either side of that band. (Weathernerds.org)

Some flash flooding is possible, but again, we’re fortunate that this is moving along quickly.

Bret is still expected to degenerate into an open wave once in the Caribbean as it encounters some extremely potent wind shear. Confidence in that outcome should be considered above average.

We will have another update for you around 7 AM CDT Thursday morning.

June 21, 2023 Outlook: Bret muscling its way toward the Windward Islands

Good morning. Tropical Storm Bret continues to churn west in the Atlantic, working its way toward the Caribbean. It’s very clearly running into some challenges that are impeding it from strengthening a whole lot at this point, and it has about 24 to 36 hours left before those challenges get even more difficult to fend off.

Tropical Storm Bret should peak in intensity sometime today or tomorrow before running into some serious hurdles in the Caribbean. Tropical Storm Watches are posted for several Caribbean islands. (NOAA)

One-sentence summary

Tropical Storm Bret, ragged as it looks this morning, could bring heavy rain and tropical storm conditions to several islands in the Lesser Antilles tomorrow before steadily weakening once it enters the Caribbean.

Happening now: Bret feeling the thorns of the rose

Besides Bret, we continue to watch Invest 93L, which has an 80 percent chance of developing over the next several days. More on that below. First, let’s walk through our main item.

Tropical Storm Bret

As of the 5 AM advisory, Bret is a moderately strong tropical storm with 60 mph winds. Tropical Storm Watches have been posted for Barbados, Dominica, Martinique, and St. Lucia. Those should be adjusted or expanded later today.

Bret is clearly fighting off some shear and dry air this morning as it works west. (Tropical Tidbits)

The environment around Bret is a bit tough right now. There is about 20 to 40 knots of westerly wind shear zipping across the northern quarter of Bret’s circulation. In the satellite loop above, you can see how ragged the northern half of Bret looks compared to the southern half, and that’s likely due to wind shear. On the northwestern side of Bret, there is a bit of dry air as well. Because of Bret’s size (it’s got a fairly large circulation), it can’t quite fend that off completely. In fact, Bret’s size may be working against it some, as it is being exposed to more adversity than a smaller storm might be.

Wind shear is impacting Bret to the north right now, and it will only get worse as Bret moves into the Caribbean. (Tropical Tidbits)

So to summarize: Bret is an acceptable tropical storm by June standards for sure, but it is dealing with some dry air and a good bit of wind shear that will probably cap Bret’s intensity and trend it weaker as it moves into the Caribbean. An Air Force reserve hurricane hunter aircraft is expected to investigate Bret today to get a better idea of what’s happening out there.

From here, Bret’s track is pretty straightforward. Virtually all of the hurricane models and global models and ensembles are in good agreement that Bret will basically track due west or just north of due west into the Caribbean, somewhere between about Dominica and St. Vincent, and near or just north of Barbados. Because of Bret’s size, many of the Leeward and Windward Islands will experience heavy rain and some version of tropical storm conditions. Because of Bret’s speed, those conditions will probably pass relatively fast.

Virtually all models have Bret degenerating into a depression by Saturday. Its remnants should continue west toward Central America, bringing some locally heavy rain along the way.

Forecast rainfall from the European model suggests about 1 to 4 inches across the southern Lesser Antilles, with the heaviest rain likely in Barbados, St. Lucia, and St. Vincent. Depending on the exact intensity and track, this could shift a bit north or south. (Weathernerds.org)

Rain totals are expected to be on the order of 1 to 4 inches from Bret due to its speed and disorganization as it tracks through the islands. Max rain totals will probably occur somewhere between Martinique and Grenada. For Puerto Rico, the Virgin Islands, and Hispaniola minimal direct impacts are expected, though seas could be a bit choppy.

Invest 93L

Meanwhile, we continue to watch Invest 93L behind Bret.

Invest 93L has a good deal of thunderstorms with it this morning, but it remains fairly disorganized. (Tropical Tidbits)

It still needs a bit of work before we start seriously considering this for upgrade status to a depression. But, it’s certainly got a good bit of storms with it, which doesn’t hurt. At this point, 93L is expected to turn northwest as it comes west, passing north of the islands and out to sea. It too will likely have a window to develop before it hits wind shear that overwhelms it and leads to weakening. Something to keep tabs on but nothing to worry much over at this time.

The medium range (days 6-10): Ain’t no party like an MDR party

The main development region (MDR) of the tropical Atlantic is more on fire than Stockton & Malone in NBA Jam (though I was more of a Barkley/Majerle guy myself). Behind Bret and 93L lies another tropical wave that will make an effort to develop in the medium range. Whether it does or does not is TBD, but even the fact that we’re talking about three systems in late June in the deep tropics is virtually unheard of. This next wave may be a bit too far south to really get going, but we’ll see.

Fantasyland (beyond day 10): Some pattern shuffling in the U.S. & Atlantic?

At this time, we don’t believe any systems will become notable in the day 10 to 15 timeframe, but there may be a little reason to watch some things. The pattern in the Atlantic, as well as high pressure responsible for extreme heat over Texas and Mexico are helping to direct traffic either out to sea or toward Central America as weak disturbances. But once we get into the day 10 to 15 timeframe, the pattern may change some. We will detail what that means in the coming days, but to reiterate, we have nothing specific to watch beyond day 10 right now.

June 19, 2023 Outlook: Is it June or September?

One look at the satellite image over the Atlantic this morning, and it’s sensible to ask what month it is currently. Even when one factors in the idea that we’ve been able to name more small storms in recent years, this is a bit ridiculous.

There are two robust disturbances in the Atlantic and a third wave emerging off Africa. While the Caribbean and Gulf are quiet, the Atlantic looks more like late August or September. (College of DuPage)

Thankfully, both systems of note in the Atlantic will probably have relatively short shelf-lives, but folks in the Lesser Antilles, Virgin Islands, and Puerto Rico should monitor the progress of these systems.

One-sentence summary

Two disturbances in the Atlantic, Invest 92L and Invest 93L have been given 100 percent and 40 percent chances (respectively) of developing this week and could become depressions or named storms in the coming days.

At least one, if not both of Invest 92L and 93L will develop in the central or eastern Atlantic this week. (NOAA)

Happening now: Investment prospectus

Two invests means two systems to discuss, so let’s take a look at their futures.

Invest 92L

Looking at Invest 92L this morning closer in on satellite, it’s pretty clear that this is almost ready to go.

Invest 92L is fairly close to becoming a depression it would seem. (Weathernerds.org)

After struggling for a couple days, the thunderstorms seem to have consolidated and there is a noticeable “spin” to the disturbance. This is likely going to become a depression not long after we publish this post.

Over the next couple days, the question becomes how much better organized 92L gets. Let’s look first at atmospheric moisture tomorrow evening.

Both 92L and 93L are likely to be initially sheltered from dry air due to their small sizes. As 92L develops and grows, the dry air to the north and west may eventually pose issues but for the next couple days, it should be good to go. (Tropical Tidbits)

Both systems are highlighted above, but looking at 92L specifically, it looks good into Tuesday evening, with ample moisture and dry air off to the north and west and far enough away for now to prevent problems for development.

What about wind shear?

Wind shear may inhibit 92L more than 93L initially, but both systems will have to fight some shear off over their life cycles. (Tropical Tidbits)

I don’t think that shear will be prohibitive to 92L, but it may keep it from intensifying as much as some models have been saying. By tomorrow evening, it’s dealing with a fair bit of shear “in the neighborhood” but perhaps not enough to keep it from becoming a tropical storm.

So where will this system go? Obviously, that’s the $10,000 question. We have enough clues in the data to make a decent call of at least what to watch and when to watch it for planning purposes in the Lesser Antilles, Virgin Islands, and Puerto Rico. If we use the GFS ensemble as a guide, we can see that 92L’s intensity is likely to “peak” in about 72 to 96 hours, or on Wednesday/Thursday. When you run 30+ different versions of the model to generate the ensemble, you get the map below.

Invest 92L will probably organize over the next 3 or 4 days before eventually hitting an inflection point, where a strong storm would turn out to sea and a weaker one would trek into the Caribbean. (Weathernerds.org)

From this point, the GFS ensemble at least takes stronger outcomes more north into the open Atlantic while weaker ones (with 1 or 2 exceptions) track into the Caribbean. It’s notable that all the European ensemble members (not shown) keep 92L weaker and track it into the Caribbean. But I prefer using the GFS ensemble as a guide, as it opens up a wider array of options for us to see right now.

Beyond day 3 or 4, it seems likely that whatever 92L becomes is going to run into a good bit of northerly shear and some broader dry air that could lead to it becoming less organized. This is why we believe that if it makes it to the islands or Caribbean, it will likely do so as a tropical storm and rain producer, certainly not without hazards but something a little less extreme for late June. But we’ll have a good idea by midweek of what this does and who it impacts.

If we look at the European ensemble mean for rainfall over the next 7 days, we can see a corridor of locally heavy rain that moves into the Lesser Antilles, with Guadeloupe through St. Lucia being in the heaviest rain. Depending on intensity and exact track, that “bullseye” could shift north or south a bit. For now, the ensemble mean prints out 1 to 4 inches of rain, but there could be some locations that see more and some flooding concerns, again depending on track and intensity, a picture that should become clearer later this week.

The heaviest rainfall from 92L will depend on the exact track and intensity. For now it looks manageable, but we’ll watch this through the week. (Weather Bell)

Invest 93L

From the maps above, it’s clear that Invest 93L is going to be in a slightly more intriguing environment for development. Much like 92L, how well organized this gets will lead to some track outcome, 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. I want to see more of how 92L behaves before worrying much about 93L, and besides 92L is the more immediate system to watch for the islands.

The medium range (days 6-10): More to come?

It seems funny that for the last 2 weeks the GFS operational model has been all about the western Caribbean and yet it’s the Atlantic that’s off to the races. There are some signs in the models that a third disturbance emerging off Africa may be something that could develop over the weekend or next week. Much like 92L and 93L, it seems unlikely it will become a big deal but this meteorologist can’t recall a busier late June in the deep Atlantic in recent memory, if ever. Of course, record warm water temperatures in the Atlantic likely mean record-type outcomes, despite El Niño.

Fantasyland (beyond day 10): Calmer?

As of right now, a cursory glance at operational models and ensembles seems to indicate that things may begin to quiet down some heading into July. We’ll see.

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Otherwise, we’ll be back with you on Tuesday morning.