Tropical Cyclone Discussion
639 WTPZ43 KNHC 010235 TCDEP3 Hurricane Rachel Discussion Number 16 NWS National Hurricane Center Miami FL EP182026 800 PM MST Wed Sep 30 2026 Satellite imagery indicates that Rachel's convective structure has changed little over the past several hours. Deep convection continues to burst near the center, with cloud-top temperatures as cold as -85 C. The latest subjective Dvorak intensity estimate from TAFB is T4.5/77 kt, while objective estimates have ranged from 65 to 85 kt. Given these estimates and the persistent deep convection, the initial intensity is increased to 80 kt. Rachel continues to move northwestward, or 320/6 kt. A northwestward motion at a slower forward speed is expected during the next day or so as the cyclone moves along the southwestern periphery of a mid-level ridge while a mid- to upper-level trough remains over the southwestern United States and northwestern Mexico. As the trough lifts northeastward and weakens, a ridge is forecast to build north of Rachel, causing the system to gradually turn west-northwestward and then westward later this week. The track guidance remains in good agreement on this overall scenario, and the latest NHC track forecast is essentially an update of the previous prediction, lying near the HCCA and GDMI aids. Environmental conditions should remain generally favorable for strengthening during the next couple of days, with very warm sea surface temperatures and plenty of mid-level moisture along the forecast track. Persistent easterly vertical wind shear of around 15 to 20 kt may be a limiting factor in the short term, but the shear is forecast to gradually relax thereafter. Rachel could strengthen rapidly by Thursday, especially if a more persistent inner core becomes established, and is forecast to become a major hurricane within the next couple of days. Thereafter, progressively cooler sea surface temperatures and dry mid-level air should induce a gradual weakening trend. The latest NHC intensity forecast is similar to the previous advisory, lying above the guidance envelope in the short term before trending toward the upper end of the guidance thereafter. Key Messages: 1. Although the core of Rachel is forecast to remain offshore of Mexico, wind gusts of tropical-storm force are possible along portions of the coast of southwestern Mexico through tonight. 2. Outer bands from Rachel will continue to produce locally heavy rainfall across portions of coastal southwest Mexico. 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 01/0300Z 19.2N 108.5W 80 KT 90 MPH 12H 01/1200Z 19.6N 109.1W 90 KT 105 MPH 24H 02/0000Z 19.8N 109.6W 95 KT 110 MPH 36H 02/1200Z 20.0N 110.3W 105 KT 120 MPH 48H 03/0000Z 20.1N 111.1W 105 KT 120 MPH 60H 03/1200Z 20.2N 111.9W 100 KT 115 MPH 72H 04/0000Z 20.4N 112.9W 90 KT 105 MPH 96H 05/0000Z 20.7N 114.9W 85 KT 100 MPH 120H 06/0000Z 20.9N 118.0W 80 KT 90 MPH