Issued at 900 AM CST Thu Oct 09 2025
000 WTPZ42 KNHC 091440 TCDEP2 Tropical Depression Seventeen-E Discussion Number 1 NWS National Hurricane Center Miami FL EP172025 900 AM CST Thu Oct 09 2025 The large area of disturbed weather located near the southwestern coast of Mexico (Invest 90E) has continued to gain organization. Convective banding has become more evident in the southern and western part of the circulation, and the latest Dvorak estimates from TAFB and SAB are T2.0 and T1.5, respectively. The convective pattern does suggest that the circulation might still be a bit elongated, but hourly observations from a cruise ship, the Norwegian Joy (C6CX3), helped to locate the main center of circulation, pressure minimum, and estimated winds. The circulation and convection are now organized enough to classify the system as a tropical depression. The center we're now tracking is somewhat discontinuous from a feature we were tracking yesterday farther to the east, and the initial motion is a rough estimate of west-northwestward, or 285/12 kt. Strong mid-level ridging over northern Mexico and the south-central U.S. is expected to steer the depression on a quick west-northwestward to northwestward track during the next 48 hours, with the center paralleling the southwestern coast of Mexico through late Friday. The system is then likely to round the western periphery of the high and move toward the Baja California peninsula in 2-3 days. The model guidance is in fairly good agreement for this first forecast, and the NHC track is close to a blend of the TVCE and HCCA consensus aids. The depression is being affected by strong easterly shear which is likely to continue for the next 24 hours. However, the system is also over very warm waters (29-30 degrees Celsius), in an environment of strong upper-level divergence, and moving quickly, which should all allow for some modest strengthening during that time. The NHC forecast is near the top end of the guidance and close to the HCCA aid in the short term. Although the shear is forecast to decrease some after 24 hours, the mid-level environment is expected to become drier and more stable while the upper-level winds become more convergent. Those changes should induce weakening while the system is approaching the southern Baja California peninsula. Although a remnant low point is provided over northwestern Mexico on day 4, it is likely that the system will dissipate before that time. KEY MESSAGES: 1. Tropical storm conditions are possible along portions of the coast of southwestern Mexico through late Friday. Interests in southern Baja California Sur should monitor the progress of the system. 2. Heavy rainfall associated with the tropical depression will impact coastal sections of southwestern Mexico through Saturday, which could result in flash flooding, particularly in areas of higher terrain. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 16.2N 100.8W 30 KT 35 MPH 12H 10/0000Z 16.8N 102.6W 40 KT 45 MPH 24H 10/1200Z 18.1N 105.1W 45 KT 50 MPH 36H 11/0000Z 19.8N 107.8W 40 KT 45 MPH 48H 11/1200Z 21.4N 109.9W 35 KT 40 MPH 60H 12/0000Z 23.3N 111.0W 30 KT 35 MPH 72H 12/1200Z 25.5N 111.2W 30 KT 35 MPH 96H 13/1200Z 29.2N 110.7W 15 KT 15 MPH...POST-TROP/REMNT LOW 120H 14/1200Z...DISSIPATED $$ Forecaster Berg
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