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Tropical Storm Bret Discussion Number  12
NWS National Hurricane Center Miami FL       AL032023
500 AM AST Thu Jun 22 2023
 
Bret threw some interesting data at us during the couple of hours 
after the release of the previous advisory.  On the last pass of the 
Air Force Reserve Hurricane Hunter aircraft through Bret's center, 
the plane measured SFMR winds as high as 69 kt and a dropsonde 
surface pressure of 996 mb with 31 kt of wind.  Significant 
mid-level westerly shear is still affecting the system, and a 0539 
UTC AMSR2 microwave pass revealed a well-defined mid-level eye 
feature displaced about a degree to the east of Bret's low-level 
center.  It appears that the strong SFMR winds were measured beneath 
the strong convection in the western mid-level eyewall feature, so 
it's possible that they were transient and convectively driven.   
That said, Bret's initial intensity was raised to 60 kt on the 2 am 
intermediate advisory out of an abundance of caution, and that 
remains the current estimate.  Another reconnaissance aircraft is 
scheduled to investigate Bret in a few hours and will hopefully 
confirm whether or not the storm is still producing winds that 
strong.

Vertical shear is expected to gradually increase over the next 
couple of days as Bret approaches an upper-level trough located over 
the eastern Caribbean Sea.  The storm could maintain its intensity 
or fluctuate in intensity through much of today, but it is expected 
to begin weakening by tonight once it crosses the Lesser Antilles 
and moves over the eastern Caribbean Sea.  Global model fields 
indicate that Bret should degenerate into a trough over the central 
Caribbean Sea by day 3, which is shown in the official forecast.

There are no changes in the track forecast reasoning.  Bret is 
moving toward the west, or 280/13 kt, steered by a low- to mid-level 
ridge to its north.  An accelerated westward motion is expected 
during the next few days as Bret weakens, and the NHC track forecast 
is a little faster than the consensus aids, hedging toward the 
faster GFS and ECMWF solutions.  Users are reminded that NHC's track 
forecasts have average errors of about 40 n mi at 24 hours, and 
there is risk of strong winds and heavy rainfall for several islands 
within the Lesser Antilles regardless of exactly where the center 
crosses the island chain.
 
 
KEY MESSAGES:
 
1. Bret is forecast to approach the Lesser Antilles today and then 
move across those islands this evening and tonight as a strong 
tropical storm.
 
2. A Hurricane Watch and a Tropical Storm Warning are in effect 
for St. Lucia, and a Tropical Storm Warning is in effect for 
Martinique and Dominica.  There is a risk of flooding from heavy 
rainfall, strong winds, and dangerous waves along the coast within 
the warning area.  A Tropical Storm Watch remains in effect for 
Barbados and St. Vincent and the Grenadines.  Additional watches or 
warnings are possible for some islands in the Lesser Antilles later 
today.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/0900Z 13.7N  56.6W   60 KT  70 MPH
 12H  22/1800Z 13.9N  58.8W   60 KT  70 MPH
 24H  23/0600Z 14.1N  61.8W   55 KT  65 MPH
 36H  23/1800Z 14.3N  65.2W   50 KT  60 MPH
 48H  24/0600Z 14.4N  68.7W   45 KT  50 MPH
 60H  24/1800Z 14.6N  72.2W   40 KT  45 MPH
 72H  25/0600Z...DISSIPATED
 
$$
Forecaster Berg
 
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