TD 19 forms near Honduras, could be potential threat for Florida next week

On Thursday morning, a late-season African easterly wave just intensified to become Tropical Depression 19.  This was located way back by Cabo Verde on November 1 and then made a slow trek across the deep tropics... it's currently centered off the eastern tip of Honduras.  It is very close to becoming the season's 18th named storm, Sara.

This is a very precarious location for a developing tropical cyclone.  On one hand, it's over extremely warm water and in low vertical wind shear, but on the other hand, it's really close to land.  Heavy rainfall will be a big hazard regardless, but how much can the winds intensify given these competing factors?  The model guidance and the NHC forecast indicate a balance, where it can reach tropical storm intensity but not much beyond that for the next 3-4 days before running into the Yucatan peninsula on Sunday.  Once over the Yucatan, it will weaken.

After it emerges from the Yucatan, there's a large spread of model scenarios.  Many of them more or less dissipate it and that's the end of the story. The rest re-intensify it to some degree over the Gulf and it gets ushered to the northeast toward Florida by a potent mid-latitude trough and cold front.  So, Florida could get some impacts from this around Wednesday, but as of right now, it appears those impacts would be relatively minor.  A hurricane landfall appears very unlikely, but it's worth keeping a close eye on this one.

These two maps show the latest storm tracks from the American model ensemble (left) and the European (right).  To help provide some context of probabilities, the left one has 30 members and the right one has 50 members.

Although unlikely, IF this should end up making landfall in Florida at hurricane intensity, it would join a very short list of November hurricane landfalls in that state.  The only previous ones in the history books are:

        Unnamed - Nov 4, 1935   - Category 2

        Kate         - Nov 21, 1985 - Category 2

        Nicole      - Nov 10, 2022 - Category 1

but none of those originated in the Caribbean Sea or the Gulf of Mexico.

And, if that happens, 2024 would tie the record set in 1886 of SIX landfalling hurricanes on the U.S. Gulf coast (the current five are Beryl, Debby, Francine, Helene, and Milton.  

And finally, for those keeping close tabs on the season stats... through today there have been 17 named storms, 11 hurricanes, and 5 major hurricanes. The average counts through this date are 13, 6, and 3.  In terms of Accumulated Cyclone Energy (ACE), that's up to about 134% of average for the date.  And if the season ended today, it would be in the top 11% of all seasons back to 1851.

As of now, there's no other activity on the foreseeable horizon, but if we do get another storm this season, the next name after Sara is Tony.

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Rafael makes rare landfall in Cuba, headed into Gulf of Mexico

Since my post on Tuesday, not only did Rafael become the season's 11th hurricane, it continued to intensify prior to reaching Cuba and made landfall as a Category 3 hurricane on Wednesday afternoon in western Cuba (the season's 5th major hurricane).

As of Thursday afternoon, Rafael is still a Category 2 hurricane as it tracks west into the central Gulf of Mexico.  It is forecast to gradually weaken, but the track remains a huge question mark beyond Saturday.  The infamous "squashed spider" look makes a return... the variability among the models and among ensemble members within a model is due to either a subtle ridge developing to its northwest (nudging it south) or a deeper trough to its north (nudging it north).

The official track forecast from NHC is trending toward the southwest turn, but don't be too surprised if it ends up moderating more to the north.  Regardless, fairly hostile conditions exist in the Gulf and Rafael's time as a hurricane will run out this weekend.  So thankfully, it does not appear that Rafael will make another impactful landfall after Cuba.

Major hurricanes are extremely rare this late in the season.  Going back to 1851, there had been only ten of them in November, not counting Rafael.  Three of those ten made landfall in Cuba as major hurricanes.  So now counting Rafael, it's four out of eleven.  Not surprisingly for this month, the activity is concentrated in the Caribbean Sea.

Speaking of the Caribbean Sea, the ocean heat content averaged over the area is back to record-breaking high.  And it's not just high, but MUCH higher than even the climatological peak of the year!  If the ocean has anything to say about the rest of hurricane season, it's not over yet.  By the way, the ocean heat content averaged over the Gulf of Mexico is also back to record-breaking high for the date.

Finally, another brief check on the Accumulated Cyclone Energy... that's up to 131% of average for the date, and in the top 12% of all years in the historical records.

This chart below contains the same data as the one above, but shown by daily amounts rather than cumulative values.  That really highlights how strange this season has been with an explosive beginning, a quiet mid-section, and an active ending.  Not every year follows the climatological curve!

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Rafael close to hurricane intensity as it approaches Cayman Islands

Since my previous post on Saturday morning, Subtropical Storm Patty did indeed pass over the Azores, then dissipated on Sunday east of the islands.  The disturbance that we've been watching for at least the past ten days was upgraded to Tropical Depression 18 on Monday morning just south of Jamaica, then to Tropical Storm Rafael on Monday afternoon.  Rafael is the season's 17th named storm.

As of Tuesday afternoon, Rafael is very close to hurricane intensity and is closing in on the Cayman Islands, then western Cuba by midday Wednesday.  It is expected to become a hurricane later today or tonight, which would be the 11th one of the season.  I have radar loops from the Caymans and Cuba at https://bmcnoldy.earth.miami.edu/tropics/radar/

Rafael will then enter the Gulf on Wednesday afternoon.  By Friday, the forecast becomes rather hazy, as there are major discrepancies among the models about what the storm will do.  In general though, it should weaken in the face in increasing wind shear and cooler water temperatures, but the track spread is noteworthy.  So, in this case, the static track cone size does not adequately capture the actual uncertainty in the 4-5-day forecast.  Thankfully, it's November and the northern Gulf is becoming relatively hostile to tropical cyclones. As of now, this does not appear to be a big heavy rain threat for the U.S. Gulf coast or inland. 

For an update on the season's activity through today, there have been 17 named storms, 10 hurricanes, and 4 major hurricanes.  The average counts by today's date are 13, 6, and 3.  The ACE is up to 126% of average for the date, or 121% of an entire average season.  Hurricane season officially ends on November 30.  If we do get another storm or two, the next names on the list are Sara and Tony.

Since the modern naming convention was introduced in 1979, this is only the 11th time (out of 46) that we reached the R name.

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Patty forms near Azores, still watching Caribbean for next storm

Since my previous post last Friday, the area of concern in the western Caribbean has still not developed into anything, but it's decidedly closer now.  This could be a threat to the Gulf coast in a week.  Elsewhere, Subtropical Storm Patty formed near the Azores on Saturday morning and will pass over the islands this weekend.  Finally, there is a tropical disturbance approaching Hispaniola and tracking west.

Starting with Subtropical Storm Patty, this is the 16th named storm of the season, and it is not expected to reach hurricane intensity.  But, it will pass directly over the Azores on Sunday bringing tropical storm conditions there.

  

By Monday, the storm will lose its subtropical characteristics and weaken, so this will not be around for very long.  The last time the Azores had a direct landfall of something was Hurricane Alex in January 2016, so it's not too common.

Next, let's go way west to the disturbance near Hispaniola.  This will unload heavy rain as it treks along the spine of the Greater Antilles.  Conditions are not too favorable for it to develop into a tropical cyclone, so it will mostly "just" be a rain-maker.  In a few days, this will likely be absorbed by the larger disturbance that's been festering in the western Caribbean for the past ten-ish days as it drifts north.

Then, we have the disturbance in the western Caribbean.  Models have been keying on its eventual development for well over a week, and now, NHC is giving it an 80% chance of becoming a tropical cyclone.  The next name on the list is Rafael.

There's finally some agreement among global models that this will develop, and track generally northward into the Gulf.  That's about where the agreement ends, but at least we have that!  The maps below show tracks from the American (left) and European (right) model ensembles out through Friday evening.  The background shading is the sea surface temperature.

The American model's ensemble is generally stronger and further east than the European's.  As far as timing goes, most members reach Cuba's latitude on Wednesday.  Then, it's too early to determine if the track will be closer to the Florida peninsula or the more likely track into the central Gulf.  Of course, once a storm is in the Gulf, it has to make landfall somewhere... there's no way out.

As far as intensity goes, a tropical storm looks very likely.  Global models tend to underestimate tropical cyclone intensity because of their relatively poorer resolution, so several of these members shown above would be at hurricane intensity.  Don't look closely at specific tracks as they inevitably shift around, but you get a sense of the likely track and intensity.

This disturbance will be sitting over the western Caribbean for the next four days or so, and the water is *extremely* warm.  The ocean heat content averaged over the Caribbean is near-record high, nearly tied with 2023, which was far above any other previous year.  The same goes for the sea surface temperature.

Hurricane season ends in four weeks, so we need to still be watching things closely, especially in an active season like this with crazy-warm ocean temperatures still lingering everywhere.

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