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Hurricane Calvin Discussion Number   8
NWS National Hurricane Center Miami FL       EP032023
500 AM HST Thu Jul 13 2023
 
Infrared and proxy-visible satellite imagery shows deep and wide 
convective bands wrapping around Calvin's center this morning. 
Recent AMSR and SSMIS microwave passes show that the system has a 
well-defined inner core, and an eyewall is forming but is not 
completely closed. The upper-level outflow wind pattern on the 
eastern side of the system has improved as well. Dvorak estimates 
for this advisory were T4.0/65 kt from both SAB and TAFB. Given 
these estimates and improved satellite trends, the initial 
intensity is set to 65 kt for this advisory. This makes Calvin the 
third hurricane of the Eastern Pacific hurricane season.

The hurricane remains within a conducive environment for additional 
strengthening to occur with low vertical wind shear and warm SSTs. 
The peak intensity of 85 kt in 36 hours remains unchanged from the 
previous NHC forecast. After 36 hours, sea surface temperatures 
along the track of Calvin will gradually begin to cool, and this 
will likely induce gradual weakening through the remainder of the 
forecast period.  The latest NHC intensity forecast lies near the 
upper-end of the guidance in the near-term, closest to HCCA, and 
then shows gradual weakening commensurate with the model consensus 
towards the end of the period.
 
Calvin continues to move westward but at a slightly slower forward 
speed of around 11 kt. A strong mid-level ridge to the north of 
Calvin will continue to move the system westward to 
west-northwestward. The cross-track spread continues to be fairly 
low, with the main difference in the models being Calvin's 
future forward speed.  The NHC track forecast lies between the 
faster HCCA model and the slower consensus and global model 
guidance, and is not too different from the previous forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/1500Z 12.7N 117.1W   65 KT  75 MPH
 12H  14/0000Z 13.0N 119.2W   75 KT  85 MPH
 24H  14/1200Z 13.5N 122.1W   80 KT  90 MPH
 36H  15/0000Z 14.1N 124.9W   85 KT 100 MPH
 48H  15/1200Z 14.7N 127.8W   80 KT  90 MPH
 60H  16/0000Z 15.3N 130.8W   75 KT  85 MPH
 72H  16/1200Z 16.0N 133.9W   70 KT  80 MPH
 96H  17/1200Z 17.0N 140.4W   55 KT  65 MPH
120H  18/1200Z 17.9N 147.6W   45 KT  50 MPH
 
$$
Forecaster Kelly/Berg
 
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