628 WTPZ44 KNHC 082053 TCDEP4 Tropical Depression Sandra Discussion Number 6 NWS National Hurricane Center Miami FL EP192021 Issued by NWS Central Pacific Hurricane Center Honolulu HI 100 PM PST Mon Nov 08 2021 Sandra's recently exposed and increasingly elongated low-level center lies to the west and southwest of an area of pulsing deep convection, due to persistent southwesterly vertical wind shear. A recent ASCAT pass indicated that winds were below tropical-storm- force, and the initial intensity for this advisory is estimated to be 30 kt, despite subjective Dvorak intensity estimates of 2.5/35 kt from TAFB/SAB. Guidance indicates that southwesterly shear near 20 kt will persist, potentially increasing in magnitude tomorrow, as the cyclone remains between an upper-level anticyclone to the east and a trough to the northwest. This environment is not conducive for a tropical cyclone's survival, and Sandra is forecast to degenerate into a remnant low on Tuesday before dissipating on Wednesday, if not sooner. The updated intensity forecast is in close agreement with HCCA guidance, as well as the GFS and ECMWF global model solutions. The initial motion estimate for this advisory is 310/08 kt, which represents a bit of a northward jog in the cyclone's track. This motion is expected to be temporary as surface high pressure is forecast to build northwest of Sandra over the next day or two. This will usher the decaying, increasingly shallow low toward the west as it becomes steered by the low-level trade wind flow. The updated track forecast follows a similar trajectory as the previous, after accounting for the recent jog toward the north, and follows a tightly clustered guidance suite. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 15.5N 117.5W 30 KT 35 MPH 12H 09/0600Z 15.5N 118.6W 30 KT 35 MPH 24H 09/1800Z 15.3N 120.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 10/0600Z 14.9N 123.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 10/1800Z...DISSIPATED $$ Forecaster Birchard