Tropical Cyclone Discussion
432 WTPZ43 KNHC 300849 TCDEP3 Hurricane Rachel Discussion Number 13 NWS National Hurricane Center Miami FL EP182026 200 AM MST Wed Sep 30 2026 Rachel is becoming better organized as the north-northeasterly vertical wind shear over the system appears to be relaxing. After strengthening into a hurricane around 0600 UTC, the system is developing better-defined convective banding features, especially over the western quadrant of the circulation. Deep convection remains very intense, with numerous cloud tops as cold as -80 deg C. A NOAA Hurricane Hunter aircraft flying a research mission into Rachel measured 84-kt winds at the 700 mb flight level. Based on this observation and the increased organization on satellite images, the advisory intensity is set to 75 kt. This is somewhat higher than the subjective Dvorak estimate and objective estimates from UW-CIMSS. The forward speed has slowed somewhat and the current motion estimate is 315/9 kt. Rachel continues to move along the southwestern side of a mid-tropospheric ridge over northern and central Mexico. The ridge is weakening due to the passage of a mid- to upper-level trough/low over the southern United States, and this is gradually slowing the steering current. As the low lifts northward during the next couple of days, this should allow another ridge to build to the north of the tropical cyclone. As a result, Rachel is forecast to turn toward the west-northwest and pass well south of the Baja California Peninsula before continuing westward away from land. The official track forecast is similar to, but slightly slower than, the previous NHC prediction. This is a blend of the latest HFIP Corrected Consensus Approach (HCCA) and Google DeepMind guidance. Given the decrease in vertical shear, and expected passage over very warm waters, significant strengthening seems likely during the next 24-36 hours. The SHIPS Rapid Intensification (RI) guidance indicates a substantially higher than normal probability of RI. The official intensity forecast anticipates that Rachel will quickly strengthen into a major hurricane by tomorrow if not sooner. This is also similar to the latest HCCA prediction. Beyond 48 hours, drier low- to mid-level air could cause some weakening. The NHC intensity forecasts is on the high side of the model guidance envelope. The outer wind radii were adjusted based on data from recent ASCAT-B/C overpasses. Key Messages: 1. Although the core of Rachel is forecast to remain offshore of Mexico, tropical-storm-force winds are expected along a portion of the coast of southwestern Mexico in the warning area this morning. 2. Outer bands from Rachel will bring locally heavy rainfall to portions of coastal southwest Mexico through Thursday. This rainfall may produce life-threatening flooding and mudslides, especially in areas of steep terrain. 3. Large waves could produce life-threatening surf and rip current conditions along the southwestern and west-central coast of Mexico and the southern Baja California Peninsula during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 17.6N 107.2W 75 KT 85 MPH 12H 30/1800Z 18.4N 108.1W 90 KT 105 MPH 24H 01/0600Z 19.2N 109.1W 100 KT 115 MPH 36H 01/1800Z 19.5N 109.7W 105 KT 120 MPH 48H 02/0600Z 19.7N 110.4W 105 KT 120 MPH 60H 02/1800Z 19.9N 111.1W 100 KT 115 MPH 72H 03/0600Z 20.1N 112.2W 90 KT 105 MPH 96H 04/0600Z 20.4N 114.3W 90 KT 105 MPH 120H 05/0600Z 20.8N 116.3W 85 KT 100 MPH