21 October 2024

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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