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Hurricane Calvin Discussion Number  12
NWS National Hurricane Center Miami FL       EP032023
500 AM HST Fri Jul 14 2023
 
Calvin has rapidly intensified since yesterday morning. The latest
geostationary satellite imagery shows the hurricane has a warm and
well-defined 15 n-mi-wide eye, with a pronounced ring of deep
convection surrounding it in recent passive microwave imagery. The
latest subjective Dvorak estimates are a consensus T5.5/102 kt from
TAFB and SAB, and the various objective estimates have continued to
rise this morning and range from 96-110 kt. The initial intensity is
raised to 105 kt for this advisory, making Calvin the first major
hurricane of the 2023 eastern Pacific season.
 
Some additional strengthening is possible today as Calvin remains
embedded within a moist, low-shear environment over sufficiently
warm sea-surface temperatures (SST). The hurricane is expected to
cross the 26C SST isotherm by tomorrow, which should cause its
intensity to level off and eventually induce some weakening as it
moves over cooler waters. Early next week, Calvin is likely to
continue weakening as it encounters less favorable environmental
conditions with increased deep-layer shear and a drier mid-level
environment along its track. Based on recent intensity trends, the
updated NHC forecast lies above the multi-model consensus aids
through 48 h, then more closely agrees with HCCA and IVCN through
the rest of the period.
 
Calvin's long-term motion is still westward, or 280/14 kt. A
well-established subtropical ridge over the eastern Pacific will
steer Calvin generally westward to west-northwestward through early
next week. The track models remain in very good agreement with
little cross-track spread noted throughout the forecast period, and
the latest NHC forecast is essentially an update of the previous
one. This brings Calvin across 140W and into the central Pacific
basin by early Monday morning, then toward the Hawaiian Islands
thereafter. Given uncertainties about the status and intensity of
Calvin near the end of the 5-day period, interests in Hawaii should
closely monitor the latest forecast updates.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/1500Z 13.6N 123.2W  105 KT 120 MPH
 12H  15/0000Z 14.0N 125.3W  110 KT 125 MPH
 24H  15/1200Z 14.7N 128.1W  100 KT 115 MPH
 36H  16/0000Z 15.3N 131.0W   90 KT 105 MPH
 48H  16/1200Z 16.0N 133.9W   75 KT  85 MPH
 60H  17/0000Z 16.6N 137.0W   60 KT  70 MPH
 72H  17/1200Z 17.2N 140.4W   50 KT  60 MPH
 96H  18/1200Z 17.9N 147.8W   40 KT  45 MPH
120H  19/1200Z 19.0N 155.5W   35 KT  40 MPH...POST-TROPICAL
 
$$
Forecaster Reinhart
 
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