Nadine and Oscar form over the weekend

Since my previous post a week ago, the two systems I discussed did become named storms.  The disturbance in the western Caribbean became Tropical Storm Nadine on the morning of the 19th, then made landfall in Belize and dissipated a day later.

Much more impressively, the wave I mentioned in that post, Invest 94L, finally developed north of the Dominican Republic.  It left the African coast on October 10, and as of 5am EDT on Saturday the 19th it had a 30% chance of formation according to NHC.  They increased that to 60% at 8am, then at 11am it was upgraded to Tropical Storm Oscar.  Amazingly, at 2pm it was upgraded again to a hurricane.  The peak winds increased from 40 to 80 mph in just three hours, and 40 to 85 mph in six hours.  This was all from data collected by aircraft reconnaissance.

For posterity, I have a 12-hour satellite loop below, spanning 8am-8pm EDT on October 19.  This captures the formation of both Nadine and Oscar, as well as Nadine's landfall and Oscar's rapid intensification.

This explosive intensification occurred near the Turks and Caicos Islands as it was headed for the eastern tip of Cuba.  Since making landfall in Cuba it has weakened to a tropical storm but is producing extremely heavy rainfall as it stalls prior to an anticipated northward turn.  It is not forecast to regain hurricane intensity as it heads toward Bermuda by the end of the week.

Oscar is one of the more notable examples in recent memory of model failure to capture genesis and then intensification even at extremely short lead times.  It was also really tiny.  James Franklin, former head of the Hurricane Specialist Unit at NHC, wrote this on Sunday: "Up until Oscar, no storm had a largest R64 of less than 10 n mi.  I believe that makes Oscar (R64=5 n mi) the smallest hurricane we know of."

There is nothing else of interest in the coming week, so after this rapid-fire development of the 14th and 15th named storms, things will slow down.  We still have 40 days remaining in hurricane season, so we still need to be paying attention though.

For an update on seasonal activity to-date, there have been 15 named storms, 10 hurricanes, and 4 major hurricanes.  The average in a full season is 14, 7, and 3.  In terms of ACE, that's at about 131% of average for the date.

There have been two Category 5 hurricanes so far (Beryl and Milton) which is extraordinary -- the other seasons with 2+ known Category 5s were 2017, 2007, 2005, 1961, 1933, and 1932.  

Of the 15 named storms, 10 of them made landfall somewhere.  All of this combines to put 2024 way toward the top end of hurricane seasons.

 

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Late-season African easterly wave could become the next storm this week

Since my previous update last Wednesday, Milton made an extremely rare landfall as a Category 3 hurricane near Tampa (Sarasota)... the only previous times this was known to have happened were 1921 and 1848.  Milton was also the fifth hurricane to make landfall on the U.S. Gulf coast; the only other time there were more was in 1886 (6).  And, Leslie finally dissipated on Saturday after spending an impressive ten days as a tropical cyclone in the central Atlantic.  The season's track map spanning Alberto through Milton is shown below.

Today's post is primarily on a late-season easterly wave that exited the African coast last Thursday morning (Oct 6th) and has continued to show some signs of development.  This time of year, we don't typically see these easterly waves have much success in developing... we're normally focused much more on the western Caribbean and the Gulf of Mexico.  As you see on the map below, there is actually an area of interest brewing in the western Caribbean as well which NHC is giving a 20% chance of formation in the coming week.

But, NHC is giving the easterly wave -- tagged as Invest 94L -- a 60% probability of becoming the season's next tropical cyclone in the coming week as it heads west toward the Windward Islands.  The tracks generally continue west to west-northwest for the foreseeable future, and the intensity generally remains weak.  In some form, it will reach the Windward Islands or just north of there on Friday. I think we need to wait until it actually develops to bother looking much beyond five days.

Regarding the future disturbance in the western Caribbean, long-range model ensembles have been hinting that it will develop and then drift westward into the Yucatan peninsula then perhaps into the Bay of Campeche.

The next two names on the list are Nadine and Oscar.  Both of those names are still original from the 1982 list, so this year would be their 8th time on a list... though Nadine has only been reached three of those times (2000, 2012, 2018), and just two times for Oscar (2012, 2018). 

As of today, neither of these features look too concerning, but it's certainly worth keeping an eye on them.  The historically-active first half of October is now behind us, but even the second half has had some infamous storms, so it's way too soon to stop paying attention.

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Milton about to make catastrophic landfall in Tampa as Category 3 hurricane

As I write this at 5pm Eastern, the center of Hurricane Milton is just 65 miles southwest of Tampa Bay and it's tracking to the northeast at 17 mph.  That puts landfall at about 9pm EDT in Tampa. It is still a formidable Category 3 hurricane with 120 mph peak sustained winds as of 5pm EDT.

The center of the hurricane will pass very close to Tampa (if not directly over it), and the bay will get an extremely high storm surge if the southern eyewall passes over the bay, and much less if the northern side passes over it.  That's the difference between onshore and offshore winds.  The exact inundation depth everywhere won't be known right away, but tide gauges in the area will help with estimates at specific sites... if the tide gauges remain intact.  Between the wind and storm surge, this day will change Tampa for a very long time.

The only other analogs that come up for this occurred in 1921 and 1848, so this is unprecedented in the past century, and a LOT has changed in Tampa since 1921!

https://bmcnoldy.earth.miami.edu/tropics/radar/

A common threat with landfalling hurricanes that sometimes gets overlooked amidst the other hazards is tornadoes.  Hurricane rainbands can be prolific tornado producers, primarily in the front-right quadrant (relative to their direction of travel).  In that radar animation above, all of those red polygons are tornado warnings that were issued during the day.  Some of the observed tornadoes were unusually large and intense -- "wedges" -- which is rather extraordinary for hurricane-spawned tornadoes.

[On the topic of radar, at the link below the animation you will find the archives of Milton's coverage from Sabancuy and Cancun in Mexico, then from La Bajada in Cuba, then from Tampa.]

As I wrote previously, Milton will almost certainly end up being a retired name. It would join other recent retired "M" storms during October: Mitch (1998), Matthew (2016), and Michael (2018).  Milton was the name chosen to replace Michael, which made landfall in Florida on October 10, 2018 as a Category 5 hurricane.

Elsewhere, Leslie is actually BACK to hurricane intensity again and the other two areas of interest are still not too likely to form (30% for the one east of Florida and 10% for the one near Cabo Verde).

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