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Tropical Storm Calvin Discussion Number   7
NWS National Hurricane Center Miami FL       EP032023
1100 PM HST Wed Jul 12 2023
 
After a brief pause during the evening, Calvin's organization 
appears to be increasing once again.  Infrared satellite imagery 
shows deep convective bands wrapping around the eastern and 
northern portions of the circulation, and very recently the 
convection has begun to coil near the center. However, there has 
been no recent microwave data to ascertain the current structure of 
the inner core.  With the earlier pause in organization, subjective 
Dvorak estimates are unchanged at T4.0/65 kt from SAB and T3.5/55 
kt from TAFB, therefore the initial intensity remains 60 kt, just 
below hurricane strength. 

Calvin is likely to become a hurricane soon as strengthening should 
resume as the storm remains within conducive atmospheric and 
oceanic conditions.  The latest NHC intensity forecast calls for a 
similar peak intensity as before.  After 36 hours, sea surface 
temperatures will gradually cool along the track of Calvin and 
mid-level moisture is also predicted to decrease.  Those less 
favorable conditions are likely to induce gradual weakening during 
the remainder of the forecast period.  The latest NHC wind speed 
forecast is close to the SHIPS intensity guidance in the short term, 
but follows a blend of the HFIP-corrected consensus
model and the IVCN multi-model consensus aid thereafter.
 
Calvin continues to move westward but at a slightly slower forward
speed of around 13 kt. A strong mid-level ridge to the north of the
cyclone should continue to steer it westward to west-northwestward
throughout the forecast period. The cross-track spread of the
guidance continues to be small but there is still notable
along-track spread (forward speed differences) in the dynamical
models.  The NHC track forecast lies between the faster
HFIP-corrected consensus model and the slower consensus aids.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/0900Z 12.4N 116.0W   60 KT  70 MPH
 12H  13/1800Z 12.7N 118.2W   70 KT  80 MPH
 24H  14/0600Z 13.2N 121.0W   80 KT  90 MPH
 36H  14/1800Z 13.8N 123.8W   85 KT 100 MPH
 48H  15/0600Z 14.4N 126.7W   80 KT  90 MPH
 60H  15/1800Z 15.0N 129.6W   75 KT  85 MPH
 72H  16/0600Z 15.7N 132.6W   70 KT  80 MPH
 96H  17/0600Z 16.8N 138.9W   55 KT  65 MPH
120H  18/0600Z 17.7N 145.7W   45 KT  50 MPH
 
$$
Forecaster Brown
 
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