20 June 2023

Bret heading for Lesser Antilles, Cindy could also form this week

We are still watching two features of interest in the deep tropics between the Caribbean and Africa: Tropical Storm Bret and Invest 93L.  As strange as it would be to have just one such system in June, having two is extraordinary.  Anomalously-warm ocean temperatures and a lack of the typical Saharan dust in the eastern Atlantic have allowed the Cabo Verde season to begin about two months early.

Tropical Depression 3 was upgraded to Tropical Storm Bret on Monday afternoon and is centered about 1000 miles east of the Lesser Antilles on Tuesday afternoon.  The latest NHC forecast no longer brings Bret up to hurricane intensity, and dissipates it in the central Caribbean over the weekend.  That closely follows most of the model guidance, with the notable exception of the HWRF model which has consistently been clinging to a strong hurricane in the eastern Caribbean. 

Bret will reach the Lesser Antilles on Thursday night, most likely as a struggling tropical storm.  Wind shear is going to increase quite a bit as it enters the Caribbean, so it probably will not make it to the western Caribbean intact.  In the slim chance that HWRF has had the right solution all along, the big divergence in forecasts between that and the others happens on Thursday; if it starts showing signs of intensifying as it crosses the Lesser Antilles, there's reason for concern in Puerto Rico and surrounding islands.

Invest 93L is being given an 80% chance of formation within the next seven days (70% within the next two days)... it would be Tropical Depression 4 or Tropical Storm Cindy if it does become a tropical cyclone.  It's trailing just 900 miles east of Bret, but as of now, the track model guidance is showing a turn to the north well before it reaches the Lesser Antilles. For intensity, no models show it reaching hurricane intensity.

As I wrote yesterday, using the 1991-2020 climatology, the average dates of the second and third named storms are July 15 and August 2.  If Bret becomes a hurricane in the coming days it would really be exceptional -- the average date of first hurricane formation is August 11!

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