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Tropical Storm Bret Discussion Number  10
NWS National Hurricane Center Miami FL       AL032023
500 PM AST Wed Jun 21 2023
 
Despite being under the influence of mid-level westerly shear, Bret
appears to have intensified slightly.  An Air Force Reserve
Hurricane Hunter aircraft measured a fairly solid area of 50- to
55-kt winds to the northeast of the center, and the central pressure
has fallen to 1000 mb.  In addition, Dvorak estimates from TAFB and
SAB are a consensus T3.5/55 kt, so Bret's initial intensity is
therefore raised to 55 kt.  The deep convection continues to favor
the eastern side of the circulation, although a burst of convection
recently formed over the center.
 
Although there is a small possibility of slight additional
strengthening, continued moderate mid-level shear is likely to keep
Bret's intensity hovering around 55 kt for the next 24 hours as it
approaches the Lesser Antilles.  Most of the intensity guidance
supports this scenario.  After that time, stronger deep-layer shear
is forecast to develop as Bret nears an upper-level trough over the
Caribbean Sea, and those conditions are expected to lead to
weakening after the cyclone crosses the Lesser Antilles island
chain.  Global model fields continue to show Bret degenerating into
an open trough by Saturday, however a 72-hour forecast point is
still shown in this forecast for continuity purposes.
 
Bret continues to move westward, or 280/13 kt, under the influence 
of low- to mid-level ridging to its north.  This steering flow is 
not expected to change, but Bret is likely to move faster toward 
the west once it begins weakening in 36 to 48 hours.  The track 
guidance envelope has been stable, and therefore the updated NHC 
track forecast has been changed very little from the morning 
forecast.  Users are reminded that NHC's track forecasts have 
average errors of about 45-50 n mi at 36 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 through
Thursday and then move across those islands late Thursday and
Thursday night as a strong tropical storm, bringing a risk of
flooding from heavy rainfall, strong winds, and dangerous waves
along the coast.
 
2. Given the uncertainty in the track and intensity forecasts, it
is still too early to specify the exact location and magnitude of
where Bret's associated hazards could occur.  A Tropical Storm
Warning is in effect for St. Lucia and Martinique, and a Tropical 
Storm Watch remains in effect for Barbados and Dominica.  Additional 
warnings are possible for some islands in the Lesser Antilles later 
tonight.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/2100Z 13.3N  53.9W   55 KT  65 MPH
 12H  22/0600Z 13.5N  55.8W   55 KT  65 MPH
 24H  22/1800Z 13.8N  58.5W   55 KT  65 MPH
 36H  23/0600Z 14.2N  61.7W   50 KT  60 MPH
 48H  23/1800Z 14.5N  65.2W   50 KT  60 MPH
 60H  24/0600Z 14.7N  68.7W   45 KT  50 MPH
 72H  24/1800Z 14.9N  72.2W   40 KT  45 MPH
 96H  25/1800Z...DISSIPATED
 
$$
Forecaster Berg
 
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