Tropical Storm Rachel Forecast Discussion
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000 WTPZ43 KNHC 291452 TCDEP3 Tropical Storm Rachel Discussion Number 10 NWS National Hurricane Center Miami FL EP182026 900 AM CST Tue Sep 29 2026 Rachel is dealing with around 20 kt of northeasterly wind shear this morning, with the estimated center position located along the far northern edge of the central dense overcast. However, a burst of deep convection, with cloud top temperatures of around -90 C, along with strong upper-level outflow suggests that the system is slowly intensifying. The latest TAFB Dvorak intensity estimate was 3.5/55 kt, while recent objective intensity estimates from UW-CIMSS range from 43-55 kt. Given the deepening convection and the slight increase in intensity estimates, the initial intensity is set at 55 kt for this advisory. The strong tropical storm is moving toward the west-northwest around 11 kt, steered by a strong mid-level ridge centered over the south-central United States. A turn toward the northwest is expected later today as high pressure builds over eastern Mexico, followed by a gradual decrease in forward speed as Rachel moves into a region with weaker steering flow. By late week, building high pressure to the northwest of the cyclone should induce a gradual turn back toward the west-northwest and then west, accompanied by a slight increase in forward speed. The updated forecast track is very similar to the previous advisory, remaining near the middle of the track forecast guidance envelope through 48 h and near the northern end of the guidance thereafter. Decreasing wind shear, sufficiently warm sea surface temperatures and favorable upper-level divergence are expected to support strengthening over the next couple of days, and Rachel is forecast to become a hurricane later today. However, Rachel could briefly move over slightly cooler waters left in the wake of Hurricane Polo tonight into early Wednesday, which may temporarily limit the rate of intensification. Thereafter, warmer waters should support additional strengthening through late this week. The latest NHC intensity forecast is near the upper-end of the guidance envelope, although it remains slightly below the HCCA solution. 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 Tropical Storm Warning area today or tonight. Tropical storm conditions are possible in the watch area tonight or on Wednesday. 2. Outer bands from Rachel will bring locally heavy rainfall to portions of coastal southwest Mexico through Thursday. This rainfall may produce areas of flooding and mudslides, especially in regions of steep terrain. 3. Large waves could produce life-threatening surf and rip current conditions along portions of the southwestern coast of Mexico during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 15.3N 105.0W 55 KT 65 MPH 12H 30/0000Z 16.5N 106.4W 65 KT 75 MPH 24H 30/1200Z 17.9N 107.7W 75 KT 85 MPH 36H 01/0000Z 19.0N 108.8W 85 KT 100 MPH 48H 01/1200Z 19.7N 109.5W 90 KT 105 MPH 60H 02/0000Z 20.1N 110.0W 90 KT 105 MPH 72H 02/1200Z 20.4N 110.6W 95 KT 110 MPH 96H 03/1200Z 20.8N 112.1W 90 KT 105 MPH 120H 04/1200Z 21.1N 114.0W 85 KT 100 MPH $$ Forecaster Adams