{"id": "1214102137919995911", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-28T09:00:00Z", "msg": "908\nWTPZ43 KNHC 280842\nTCDEP3\n \nTropical Storm Rachel Discussion Number   5\nNWS National Hurricane Center Miami FL       EP182026\n300 AM CST Mon Sep 28 2026\n \nRachel has intensified since the previous advisory. The METOP-C \nAdvanced Scatterometer sampled the center and western half of the \nsystem around 0431z, and found reliable winds to 40 kt. This is in \nagreement with the objective satellite intensity estimates from \nUW-CIMMS and a subjective Dvorak of T3.0/45 kt from TAFB. Therefore, \nthe initial intensity is set at 40 kt for this advisory, and there \nis more confidence in the initial position of the cyclone.\n \nThe cyclone is now moving toward the west-northwest at 290/7 kt, and \nit appears Rachel is starting to move a bit faster. A deep-layer \nridge building over north-central Mexico is forecast to steer the \ncyclone west-northwestward, with some acceleration in forward motion \nthrough early next week. On Thursday, a trough over the southwestern \nUnited States will weaken the ridge somewhat, leading to diminished \nsteering flow near Rachel and a deceleration in the cyclone's \nwest-northwestward motion. The new initial position, informed by the \naforementioned scatterometer pass, lies to the right of the previous \nofficial forecast track. As a result, the new forecast is adjusted \nto the right of the previous one, and blends toward the most recent \nGoogle DeepMind (GDM) and HFIP Corrected Consensus Approach (HCCA) \nguidance.\n \nRachel is apparently less-than-hindered by the northeasterly \nvertical wind shear diagnosed near the tropical storm. All other \nenvironmental parameters support intensification, and the new \nintensity forecast is largely an update of the previous one. The \nintensity forecast is again on the higher end of the guidance \nenvelope, and blends the GDM and HCCA solutions. Rachel is forecast \nto become a hurricane on Tuesday. There is some uncertainty beyond \n72 hr, with some of the guidance showing weakening during that time. \nIt is not entirely clear to me why weakening would occur during this \ntime-frame, given favorable dynamics and thermodynamics indicated \nacross the deterministic global model fields. Rachel could track \nover some of the cool wake from Hurricane Polo, though recent \ndrifter data captured vertical profiles that show high ocean heat \ncontent (OHC) persists in the region. Given the uncertainty, and the \nshift in track more east of the cool wake, I show Rachel maintaining \nits intensity from 72 through 120 hr.\n \nKey Messages:\n \n1. Although the core of Rachel is forecast to remain offshore of\nMexico, tropical storm force winds are possible along a portion of\nthe coast of southwestern Mexico in the Tropical Storm Watch area\non Tuesday.\n \n2. Large waves could produce life-threatening surf and rip current\nconditions along portions of the southwestern coast of Mexico during\nthe next several days.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  28/0900Z 13.4N 100.4W   40 KT  45 MPH\n 12H  28/1800Z 13.9N 101.7W   50 KT  60 MPH\n 24H  29/0600Z 14.9N 103.5W   55 KT  65 MPH\n 36H  29/1800Z 16.1N 105.3W   60 KT  70 MPH\n 48H  30/0600Z 17.3N 106.6W   70 KT  80 MPH\n 60H  30/1800Z 18.2N 107.6W   80 KT  90 MPH\n 72H  01/0600Z 19.0N 108.5W   85 KT 100 MPH\n 96H  02/0600Z 19.6N 109.2W   85 KT 100 MPH\n120H  03/0600Z 20.4N 110.0W   85 KT 100 MPH\n \n"}