000
WTNT43 KNHC 162046
TCDAT3
 
Tropical Storm Henri Discussion Number   4
NWS National Hurricane Center Miami FL       AL082021
500 PM AST Mon Aug 16 2021
 
Deep convection has persisted near and southeast of the center 
of the small tropical cyclone today, and subjective Dvorak 
intensity estimates were a consensus T2.5 (35 kt) at 1800 UTC.  
Objective estimates from ADT and SATCON also support tropical 
storm status, therefore the depression has been upgraded to a 
35-kt tropical storm with this advisory.  Henri (ahn-REE) becomes 
the eighth named storm of the 2021 Atlantic hurricane season.  This 
is the fourth-earliest eighth storm on record with only 2020, 
2005, and 1936 having the eighth-named storm form earlier in the 
season.

Henri is located over warm waters, but is currently being affected 
by light to moderate northerly shear and dry mid-level air in the 
surrounding environment.  Although these conditions are not overly 
conducive for strengthening, most of the intensity guidance 
supports gradual intensification over the next 24 to 48 hours.  
After that time, a significant increase in northeasterly 
upper-level winds is depicted by the global models over the system, 
which is likely to halt further strengthening.  In fact, given the 
small size of Henri, it is likely to be more susceptible to the 
increase in shear, and it could weaken faster than indicated below. 
The HWRF remains more aggressive, but given the expected increase in 
shear, that solution still does not seem likely.  The NHC intensity 
forecast is in best agreement with the LGEM model, and is slightly 
below the IVCN intensity consensus.

The tropical storm is moving south-southwestward or 200/6 kt. Henri 
is forecast to move west-southwestward during the next 12-24 hours 
around the southeastern side of a mid-tropospheric high over the 
western Atlantic.  After that time, Henri should turn westward as 
the ridge shifts eastward to the north of the tropical cyclone, and 
after 72 hours Henri is expected to approach the western extent of 
the ridge and should turn northward and then north-northeastward. 
The dynamical model guidance is in somewhat better agreement during 
the next 48-72 hours, but there remains some spread later in 
the period as to how sharp of northward turn occurs.  The new NHC 
track forecast is similar to the previous advisory and lies near 
the center of the guidance envelope.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/2100Z 31.0N  62.9W   35 KT  40 MPH
 12H  17/0600Z 30.5N  63.4W   40 KT  45 MPH
 24H  17/1800Z 30.3N  64.2W   45 KT  50 MPH
 36H  18/0600Z 30.2N  65.4W   50 KT  60 MPH
 48H  18/1800Z 30.2N  66.9W   50 KT  60 MPH
 60H  19/0600Z 30.3N  68.5W   50 KT  60 MPH
 72H  19/1800Z 30.5N  69.9W   45 KT  50 MPH
 96H  20/1800Z 31.8N  70.2W   45 KT  50 MPH
120H  21/1800Z 34.2N  68.4W   45 KT  50 MPH
 
$$
Forecaster Brown