Tropical Storm Calvin Discussion Number 21
NWS National Hurricane Center Miami FL EP032023
1100 AM HST Sun Jul 16 2023
The satellite presentation of Calvin has not changed much since the
last advisory. Satellite images show a partially exposed low-level
circulation with a small area of moderate to deep convection near
the center. Satellite intensity estimates continue to fall, and a
blend of the latest Dvorak final-T and current intensity estimates
from TAFB and SAB support lowering the intensity to 55 kt.
Continued weakening is expected as Calvin moves over 24C SSTs and
into a drier, more stable environment during the next couple of
days. The cyclone could cease producing organized convection during
this time. Although environmental and oceanic conditions remain
marginal on its approach to Hawaii, there is still support in GFS,
ECMWF, and HAFS model-simulated satellite imagery for some new
bursts of convection as Calvin moves closer to the islands. So, the
NHC forecast keeps Calvin a tropical cyclone through 72 h, although
post-tropical status could occur sooner than forecast. Regardless,
the cyclone should still be producing some tropical-storm-force
winds in its northern semicircle upon its closest approach to
Hawaii, especially given the storm's fast forward motion.
There has been no change to the track forecast reasoning. A
mid-level ridge over the eastern Pacific is expected to steer Calvin
generally westward into the central Pacific basin late tonight or
early Monday and toward the Hawaiian Islands on Tuesday. The NHC
forecast shows the center of Calvin passing near or over the Big
Island of Hawaii early Wednesday, then continuing westward and
becoming post-tropical on Thursday before dissipating. The guidance
envelope has trended slightly southward this cycle, but little
change was required to the NHC forecast as it still lies near the
latest HFIP corrected consensus approach (HCCA) aid.
While the exact storm track near Hawaii is still uncertain, there is
potential for portions of the state to experience some heavy
rainfall, dangerous surf and rip current conditions, and minor wind
impacts from Calvin. A Tropical Storm Watch may be required for
portions of the main Hawaiian Islands later today.
KEY MESSAGES:
1. Calvin is forecast to approach the Hawaiian Islands during the
next couple of days or so, bringing the potential for heavy
rainfall and dangerous surf and rip current conditions. A Tropical
Storm Watch could be issued for portions of the main Hawaiian
Islands later today.
FORECAST POSITIONS AND MAX WINDS
INIT 16/2100Z 16.1N 136.3W 55 KT 65 MPH
12H 17/0600Z 16.5N 138.8W 45 KT 50 MPH
24H 17/1800Z 17.1N 142.3W 40 KT 45 MPH
36H 18/0600Z 17.5N 145.9W 40 KT 45 MPH
48H 18/1800Z 18.1N 149.7W 35 KT 40 MPH
60H 19/0600Z 18.7N 153.4W 35 KT 40 MPH
72H 19/1800Z 19.2N 157.0W 35 KT 40 MPH
96H 20/1800Z 20.0N 163.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 21/1800Z...DISSIPATED
$$
Forecaster Reinhart
NWS National Hurricane Center Miami FL EP032023
1100 AM HST Sun Jul 16 2023
The satellite presentation of Calvin has not changed much since the
last advisory. Satellite images show a partially exposed low-level
circulation with a small area of moderate to deep convection near
the center. Satellite intensity estimates continue to fall, and a
blend of the latest Dvorak final-T and current intensity estimates
from TAFB and SAB support lowering the intensity to 55 kt.
Continued weakening is expected as Calvin moves over 24C SSTs and
into a drier, more stable environment during the next couple of
days. The cyclone could cease producing organized convection during
this time. Although environmental and oceanic conditions remain
marginal on its approach to Hawaii, there is still support in GFS,
ECMWF, and HAFS model-simulated satellite imagery for some new
bursts of convection as Calvin moves closer to the islands. So, the
NHC forecast keeps Calvin a tropical cyclone through 72 h, although
post-tropical status could occur sooner than forecast. Regardless,
the cyclone should still be producing some tropical-storm-force
winds in its northern semicircle upon its closest approach to
Hawaii, especially given the storm's fast forward motion.
There has been no change to the track forecast reasoning. A
mid-level ridge over the eastern Pacific is expected to steer Calvin
generally westward into the central Pacific basin late tonight or
early Monday and toward the Hawaiian Islands on Tuesday. The NHC
forecast shows the center of Calvin passing near or over the Big
Island of Hawaii early Wednesday, then continuing westward and
becoming post-tropical on Thursday before dissipating. The guidance
envelope has trended slightly southward this cycle, but little
change was required to the NHC forecast as it still lies near the
latest HFIP corrected consensus approach (HCCA) aid.
While the exact storm track near Hawaii is still uncertain, there is
potential for portions of the state to experience some heavy
rainfall, dangerous surf and rip current conditions, and minor wind
impacts from Calvin. A Tropical Storm Watch may be required for
portions of the main Hawaiian Islands later today.
KEY MESSAGES:
1. Calvin is forecast to approach the Hawaiian Islands during the
next couple of days or so, bringing the potential for heavy
rainfall and dangerous surf and rip current conditions. A Tropical
Storm Watch could be issued for portions of the main Hawaiian
Islands later today.
FORECAST POSITIONS AND MAX WINDS
INIT 16/2100Z 16.1N 136.3W 55 KT 65 MPH
12H 17/0600Z 16.5N 138.8W 45 KT 50 MPH
24H 17/1800Z 17.1N 142.3W 40 KT 45 MPH
36H 18/0600Z 17.5N 145.9W 40 KT 45 MPH
48H 18/1800Z 18.1N 149.7W 35 KT 40 MPH
60H 19/0600Z 18.7N 153.4W 35 KT 40 MPH
72H 19/1800Z 19.2N 157.0W 35 KT 40 MPH
96H 20/1800Z 20.0N 163.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 21/1800Z...DISSIPATED
$$
Forecaster Reinhart
