Issued at 800 PM PDT Wed Oct 01 2025
000 WTPZ45 KNHC 020242 TCDEP5 Tropical Storm Octave Discussion Number 8 NWS National Hurricane Center Miami FL EP152025 800 PM PDT Wed Oct 01 2025 The satellite presentation of Octave has improved slightly since the previous advisory, with better-defined curved banding developing on the south and west sides of the low-level center. The cyclone continues to be influenced by moderate easterly wind shear, analyzed at around 22 kt by UW-CIMSS. This shear is restricting outflow in the eastern semicircle and keeping the low-level center displaced on the eastern side of the deeper convection. The most recent subjective Dvorak intensity estimate from TAFB was 3.5/55 kt, while the UW-CIMSS objective estimates have ranged from 45 to 58 kt since the prior advisory. Based on a blend of these data, and considering the modest improvement in the satellite presentation during the past several hours, the initial intensity is held at 55 kt for this advisory. Octave is estimated to be moving west-northwestward, or 290 degrees at 6 kt. This general motion is expected to continue for the next several days as Octave is steered along the southern periphery of a subtropical ridge located to its north. By days 4 and 5, Octave is forecast to slow considerably and turn northward, then eastward, as a longwave trough approaches from the northwest and the subtropical ridge to its east weakens due to the influence of a larger tropical cyclone developing offshore of the southwestern or west-central coast of Mexico. The new NHC track forecast is similar to the previous one and remains close to a blend of the multi-model consensus and AI-based track aids. Octave will remain over warm waters and within a moist environment for the next few days. However, vertical wind shear is forecast to fluctuate between moderate and strong levels during the next 36 hours, which should inhibit significant intensification during that period. As a result, the official forecast indicates little change in strength through that time. Some modest strengthening is then forecast between 48 and 96 hours as the shear relaxes, although sea surface temperatures will gradually cool and mid-level moisture is expected to decrease. The official forecast now shows Octave reaching hurricane intensity by days 3 and 4, though this remains below the more aggressive solutions from some regional hurricane models. By day 5, weakening should be well underway as Octave moves into a drier, more stable air mass, over cooler waters around 26C, and experiences increasing shear. The official forecast is similar to the previous one and remains most closely aligned with the HCCA and FSSE intensity aids. FORECAST POSITIONS AND MAX WINDS INIT 02/0300Z 12.2N 117.0W 55 KT 65 MPH 12H 02/1200Z 12.6N 117.8W 55 KT 65 MPH 24H 03/0000Z 13.1N 119.1W 55 KT 65 MPH 36H 03/1200Z 13.5N 120.5W 55 KT 65 MPH 48H 04/0000Z 14.0N 121.9W 60 KT 70 MPH 60H 04/1200Z 14.5N 123.0W 60 KT 70 MPH 72H 05/0000Z 15.0N 123.8W 65 KT 75 MPH 96H 06/0000Z 15.7N 123.2W 65 KT 75 MPH 120H 07/0000Z 16.0N 121.5W 50 KT 60 MPH $$ Forecaster Jelsema (CPHC)
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