{"id": "1214457921165524999", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-29T15:00:00Z", "msg": "575\nWTPZ43 KNHC 291452\nTCDEP3\n \nTropical Storm Rachel Discussion Number  10\nNWS National Hurricane Center Miami FL       EP182026\n900 AM CST Tue Sep 29 2026\n \nRachel is dealing with around 20 kt of northeasterly wind shear this \nmorning, with the estimated center position located along the far \nnorthern edge of the central dense overcast. However, a burst of \ndeep convection, with cloud top temperatures of around -90 C, along \nwith strong upper-level outflow suggests that the system is slowly \nintensifying. The latest TAFB Dvorak intensity estimate was 3.5/55 \nkt, while recent objective intensity estimates from UW-CIMSS range \nfrom 43-55 kt. Given the deepening convection and the slight \nincrease in intensity estimates, the initial intensity is set at 55 \nkt for this advisory. \n \nThe strong tropical storm is moving toward the west-northwest around \n11 kt, steered by a strong mid-level ridge centered over the \nsouth-central United States. A turn toward the northwest is expected \nlater today as high pressure builds over eastern Mexico, followed by \na gradual decrease in forward speed as Rachel moves into a region \nwith weaker steering flow. By late week, building high pressure to \nthe northwest of the cyclone should induce a gradual turn back \ntoward the west-northwest and then west, accompanied by a slight \nincrease in forward speed. The updated forecast track is very \nsimilar to the previous advisory, remaining near the middle of the \ntrack forecast guidance envelope through 48 h and near the northern \nend of the guidance thereafter. \n \nDecreasing wind shear, sufficiently warm sea surface temperatures \nand favorable upper-level divergence are expected to support \nstrengthening over the next couple of days, and Rachel is forecast \nto become a hurricane later today. However, Rachel could briefly \nmove over slightly cooler waters left in the wake of Hurricane Polo \ntonight into early Wednesday, which may temporarily limit the rate \nof intensification. Thereafter, warmer waters should support \nadditional strengthening through late this week. The latest NHC \nintensity forecast is near the upper-end of the guidance envelope, \nalthough it remains slightly below the HCCA solution. \n \n \nKey Messages:\n \n1. Although the core of Rachel is forecast to remain offshore of \nMexico, tropical-storm-force winds are expected along a portion of \nthe coast of southwestern Mexico in the Tropical Storm Warning area \ntoday or tonight. Tropical storm conditions are possible in the \nwatch area tonight or on Wednesday.\n \n2. Outer bands from Rachel will bring locally heavy rainfall to\nportions of coastal southwest Mexico through Thursday. This rainfall\nmay produce areas of flooding and mudslides, especially in regions\nof steep terrain.\n \n3. 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  29/1500Z 15.3N 105.0W   55 KT  65 MPH\n 12H  30/0000Z 16.5N 106.4W   65 KT  75 MPH\n 24H  30/1200Z 17.9N 107.7W   75 KT  85 MPH\n 36H  01/0000Z 19.0N 108.8W   85 KT 100 MPH\n 48H  01/1200Z 19.7N 109.5W   90 KT 105 MPH\n 60H  02/0000Z 20.1N 110.0W   90 KT 105 MPH\n 72H  02/1200Z 20.4N 110.6W   95 KT 110 MPH\n 96H  03/1200Z 20.8N 112.1W   90 KT 105 MPH\n120H  04/1200Z 21.1N 114.0W   85 KT 100 MPH\n \n"}