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Tropical Storm Xavier Forecast Discussion Number 4
2018-11-03 15:34:25| National Hurricane Center (East Pacific)
Issued at 900 AM MDT Sat Nov 03 2018 000 WTPZ45 KNHC 031434 TCDEP5 Tropical Storm Xavier Discussion Number 4 NWS National Hurricane Center Miami FL EP252018 900 AM MDT Sat Nov 03 2018 Although Xavier is being affected by 20-25 kt of westerly vertical shear, the cyclone continues to generate a large burst of convection and the low-level center is now located under the southwestern edge of the convective mass. The initial intensity is increased to 45 kt, which is at the upper end of the various satellite intensity estimates. During the next 24 h, the dynamical models suggest that an upper-level trough located to the north and west of Xavier should provide upper-level divergence over the cyclone. This could allow some additional strengthening despite the ongoing shear. After that time, the trough is forecast to dissipate, leaving the tropical storm in an area of upper-level convergence and moderate to strong shear that should cause it to weaken. Based on this evolution, the intensity forecast calls for a little more strengthening during the next 12-24 h, followed by gradual weakening through the remainder of the forecast period, with the cyclone becoming a remnant low in about 96 h. The forecast follows the overall trend of the intensity guidance and lies near the upper edge of the guidance. Based on a combination of conventional and microwave satellite fixes, the initial motion is estimated to be 060/7. There is again little change to the forecast track philosophy. Xavier should turn northeastward and then northward during the next 24 h toward a weakness in the subtropical ridge created by the aforementioned trough. As Xavier weakens and becomes a shallow system, the cyclone should turn toward the west-northwest and west as it is steered by the low-level flow to the south of the subtropical ridge. The new forecast track is nudged just a little to the east and north of the previous track, but it remains close to the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 15.3N 107.0W 45 KT 50 MPH 12H 04/0000Z 15.8N 106.4W 50 KT 60 MPH 24H 04/1200Z 16.6N 106.0W 50 KT 60 MPH 36H 05/0000Z 17.3N 106.1W 45 KT 50 MPH 48H 05/1200Z 17.4N 106.5W 40 KT 45 MPH 72H 06/1200Z 17.5N 108.0W 30 KT 35 MPH 96H 07/1200Z 17.5N 111.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 08/1200Z 18.0N 113.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven
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