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Tropical Storm Henri Discussion Number   6
NWS National Hurricane Center Miami FL       AL082021
500 AM AST Tue Aug 17 2021
 
Earlier this evening Henri was undergoing a sheared bursting 
pattern, with intermittent deep convection trying to develop near 
the center, but northwesterly shear would quickly diminish the 
convective coverage. However, over the past several hours the 
convection has become more persistent, and covers at least the 
southeastern portion of the low-level center. As such, the latest 
subjective Dvorak intensity estimates from TAFB and SAB are now 
both 3.0 (45 kt), and therefore 45 kt will be the initial advisory 
intensity.
 
Henri is forecast to remain over warm waters and in an environment 
of light to moderate northerly shear for the next 24 h, so some 
strengthening is expected during that time. After 24 h, global 
models indicate that the shear magnitude will double, which should 
prevent any further strengthening and possibly weaken the cyclone. 
The latest NHC intensity forecast was adjusted a little higher than 
the previous due to both the increase in initial intensity, and 
slight increase in the model intensity guidance. This forecast 
closely follows the LGEM solution and is just a little lower than 
the IVCN consensus.
 
The tropical storm continues to move slowly southwest, or 240/04 kt 
to the southeast of a mid-level ridge. This ridge is forecast to 
shift to the east over the next several days, which would result in 
the tropical storm making a gradual clockwise turn throughout much 
of the forecast period. Tonight, Henri is forecast to turn westward 
with a increase in forward motion and pass well south of Bermuda. In 
a few days, the cyclone should turn to the northwest then north, 
followed by a turn to the northeast around the western periphery of 
the ridge. There continues to be some spread in how far west Henri 
will go before it begins to turn to the north, and the latest 
guidance has made a slight shift to the left. The official NHC 
forecast is near the previous one through 48 h, then is a little 
left of it thereafter, yet still remains to the right of the bulk of 
the consensus guidance beyond 48 h.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/0900Z 30.6N  63.7W   45 KT  50 MPH
 12H  17/1800Z 30.4N  64.4W   50 KT  60 MPH
 24H  18/0600Z 30.3N  65.7W   55 KT  65 MPH
 36H  18/1800Z 30.2N  67.1W   55 KT  65 MPH
 48H  19/0600Z 30.3N  68.6W   55 KT  65 MPH
 60H  19/1800Z 30.8N  69.8W   55 KT  65 MPH
 72H  20/0600Z 31.6N  70.6W   55 KT  65 MPH
 96H  21/0600Z 34.0N  69.1W   55 KT  65 MPH
120H  22/0600Z 36.0N  66.0W   55 KT  65 MPH
 
$$
Forecaster Latto
 
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