ZCZC MIATCDEP3 ALL
TTAA00 KNHC DDHHMM
 
Tropical Storm Calvin Discussion Number   5
NWS National Hurricane Center Miami FL       EP032023
1100 AM HST Wed Jul 12 2023

Tropical Storm Calvin continues to strengthen this morning, with an 
improved structure on hi-res GOES visible satellite imagery. A 
curved band is beginning to wrap around the center, however, the 
band has not yet completely filled in around the northern side. 
Subjective satellite Dvorak estimates from TAFB and SAB were T3.5/55 
kt and T3.0/45 kt, respectively, while the latest objective 
estimates from SATCON and ADT are higher than 55 kt. Given the 
improved structure on satellite, the initial intensity is raised to 
55 kt for this advisory based on a blend of the various intensity 
estimates.
 
Calvin is in a conducive environment for strengthening, with 
light-to-moderate vertical wind shear, and warm sea surface 
temperatures. Steady strengthening is forecast the next several 
days, with Calvin potentially becoming a hurricane later tonight. 
Rapid intensification (RI) guidance has increased on this 
cycle and now shows a roughly 3-in-10 chance for RI to occur during 
the next 24 hours.  Therefore, the NHC intensity forecast is near 
the upper end of the guidance, and the peak intensity has been 
slightly raised from the previous forecast. By the weekend, Calvin 
is expected to cross over cooler SSTs which will likely cause 
gradual weakening through the remainder of the forecast period.
 
Calvin is moving westward or 275/15 kt. A strong ridge located to 
the north of Calvin will continue to steer the cyclone westward to 
west-northwestward throughout the forecast period. Model guidance 
is in fairly good agreement with the track--the main difference is 
the forward speed of Calvin with some models moving the storm a 
little faster (particularly HCCA). The updated NHC track forecast 
lies near the center of the guidance envelope, but is a little on 
the faster side of forecast ensembles.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/2100Z 12.8N 113.8W   55 KT  65 MPH
 12H  13/0600Z 12.9N 115.9W   65 KT  75 MPH
 24H  13/1800Z 13.1N 118.6W   75 KT  85 MPH
 36H  14/0600Z 13.6N 121.3W   85 KT 100 MPH
 48H  14/1800Z 14.3N 124.3W   85 KT 100 MPH
 60H  15/0600Z 14.9N 127.3W   80 KT  90 MPH
 72H  15/1800Z 15.6N 130.4W   75 KT  85 MPH
 96H  16/1800Z 16.8N 136.7W   60 KT  70 MPH
120H  17/1800Z 17.8N 143.7W   50 KT  60 MPH
 
$$
Forecaster Kelly/Berg
 
NNNN