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Hurricane Calvin Discussion Number   9
NWS National Hurricane Center Miami FL       EP032023
1100 AM HST Thu Jul 13 2023
 
High-resolution 1-minute visible satellite imagery shows the inner 
core of Calvin becoming better defined with deep convective banding 
wrapping around the center. In the past hour or so, satellite 
trends show what may be the beginning stages of eye trying to 
develop, and this would be in agreement with what was reflected in 
microwaves passes from earlier this morning. The upper-level outflow 
wind pattern has continued to become better established around the 
cyclone as well. Subjective satellite Dvorak estimates were T4.0/65 
kt and T4.5/77 kt from SAB and TAFB, respectively. Given the 
improved satellite structure and a blend of the subjective intensity 
estimates, the initial intensity is set to 70 kt for this advisory.
 
The cyclone continues to be over warm sea surface temperatures 
and within a low vertical wind shear environment, with gradual 
strengthening forecast for the next day or so. The forecast peak 
intensity remains 85 kt in 24-36 hours. However, there was some 
model guidance this cycle, particularly HCCA, that showed the 
potential for the system to become a little bit stronger than that. 
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 short term, then shows gradual weakening, and is near the 
consensus aids by the end of the period.
 
Calvin is moving westward at 275/12 kt. A strong mid-level ridge to 
the north of Calvin will continue to move the system westward to 
west-northwestward. The track guidance continues to be in fairly 
good agreement, with the consensus aids and HCCA coming into better 
agreement with the forward speed compared to previous model cycles. 
The NHC track forecast is not too different from the previous 
forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/2100Z 12.8N 118.7W   70 KT  80 MPH
 12H  14/0600Z 13.2N 120.8W   80 KT  90 MPH
 24H  14/1800Z 13.7N 123.7W   85 KT 100 MPH
 36H  15/0600Z 14.3N 126.5W   85 KT 100 MPH
 48H  15/1800Z 14.9N 129.4W   80 KT  90 MPH
 60H  16/0600Z 15.6N 132.3W   75 KT  85 MPH
 72H  16/1800Z 16.2N 135.2W   65 KT  75 MPH
 96H  17/1800Z 17.3N 141.9W   50 KT  60 MPH
120H  18/1800Z 18.2N 149.1W   40 KT  45 MPH
 
$$
Forecaster Kelly/Berg
 
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