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Tropical Storm Kevin Forecast Discussion Number 8
2021-08-09 10:36:43| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Mon Aug 09 2021 320 WTPZ41 KNHC 090836 TCDEP1 Tropical Storm Kevin Discussion Number 8 NWS National Hurricane Center Miami FL EP112021 300 AM MDT Mon Aug 09 2021 Kevin is a sheared tropical cyclone. Satellite imagery indicates the low-level center lies near the edge of the dense overcast, which has a sharp border in the northeastern quadrant of the cyclone. The associated deep convection is displaced well to the southwest of Kevin's partially exposed center. Recent scatterometer data only show 25 to 30-kt winds near the center, but the full southwestern quadrant where the most intense convection is occurring was not sampled. The initial intensity is lowered to 45 kt for this advisory, in best agreement with the subjective final Dvorak T-numbers from TAFB and SAB. This estimate could still be generous, however. The cyclone has turned west-northwestward during the past 12 h, and its estimated motion is now 290/6 kt. The track forecast reasoning is unchanged, as Kevin is expected to move west-northwestward for most of the forecast period along the southwestern periphery of a mid-level ridge. The official NHC track forecast has been adjusted a bit northward again this cycle, following the trend of the latest multi-model consensus aids. Although Kevin has been embedded within a favorable thermodynamic environment, 15 to 20 kt of northeasterly shear has thus far limited its rate of strengthening. This shear is expected to persist for the next couple of days, so it seems likely that Kevin will continue to struggle intensifying, despite warm SSTs and a moist, unstable environment. By the time the vertical wind shear diminishes, Kevin will have gained enough latitude that the underlying SSTs will be unfavorable for further strengthening. The new intensity guidance is much lower than previous cycles, and so the latest NHC intensity forecast has been reduced by 5 to 10 kt at all forecast hours. Thus, Kevin is no longer forecast to become a hurricane. By day 5, the system is expected to become a post-tropical remnant low over sub-22 deg C waters. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 16.3N 110.9W 45 KT 50 MPH 12H 09/1800Z 16.8N 111.9W 50 KT 60 MPH 24H 10/0600Z 17.6N 113.3W 50 KT 60 MPH 36H 10/1800Z 18.4N 115.0W 55 KT 65 MPH 48H 11/0600Z 19.2N 116.5W 55 KT 65 MPH 60H 11/1800Z 20.1N 118.2W 50 KT 60 MPH 72H 12/0600Z 21.0N 120.2W 45 KT 50 MPH 96H 13/0600Z 22.5N 124.5W 30 KT 35 MPH 120H 14/0600Z 24.0N 129.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Reinhart/Pasch
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