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Tropical Storm Xavier Forecast Discussion Number 9
2018-11-04 21:40:32| National Hurricane Center (East Pacific)
Issued at 300 PM CST Sun Nov 04 2018 000 WTPZ45 KNHC 042040 TCDEP5 Tropical Storm Xavier Discussion Number 9 NWS National Hurricane Center Miami FL EP252018 300 PM CST Sun Nov 04 2018 After being sheared off this morning, deep convection has redeveloped and persisted over Xavier's center of circulation. Dvorak Current Intensity numbers from TAFB and SAB remain 3.0, and the latest UW-CIMSS SATCON estimate is 43 kt. The initial intensity therefore remains 45 kt. Although shear analyses indicate that about 25 kt of southwesterly shear is affecting Xavier, an upper-level trough in the vicinity appears to be producing a decent amount of divergence aloft to support the ongoing convection. The global models show that trough dissipating and the upper flow becoming unidirectional within 12 hours, which should cut off the divergence and allow the adverse effects of shear and dry air to take over. As a result, gradual weakening is expected during the next couple of days, and Xavier may cease to produce organized deep convection (and thus become a remnant low) in 36-48 hours. The remnant low should dissipate by day 4, if not sooner. The updated NHC intensity forecast is conservative, following continuity from the previous forecast and lying near the upper bound of the intensity models. Xavier's motion still appears to be slowly northward, or 350/5 kt. The global models, most of which assume that Xavier will become a shallow system soon, show the cyclone turning northwestward and west-northwestward during the next 24 hours. While this seems reasonable, as long as Xavier maintains vertical integrity, it will likely continue moving closer to the right side of the guidance envelope. With the assumption that deep convection won't dissipate right away, the NHC track forecast is to the right of the consensus aids, close to the ECMWF solution, during the first 24 hours. After 24 hours, it remains close to the TVCN multi-model consensus. A 1600 UTC ASCAT pass indicated that Xavier's tropical-storm-force wind field on the east side was larger than previously estimated, with those winds lying near the coast of southwestern Mexico. As a result, the government of Mexico issued a Tropical Storm Warning for a portion of the coasts of Michoacan, Colima, and Jalisco. Locally heavy rainfall and large swells are also likely to affect the coast of southwestern Mexico during the next day or two. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 18.1N 105.5W 45 KT 50 MPH 12H 05/0600Z 18.7N 106.0W 40 KT 45 MPH 24H 05/1800Z 19.2N 107.1W 35 KT 40 MPH 36H 06/0600Z 19.5N 108.2W 30 KT 35 MPH 48H 06/1800Z 19.6N 109.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 07/1800Z 19.4N 111.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 08/1800Z 19.0N 114.0W 15 KT 15 MPH...POST-TROP/REMNT LOW 120H 09/1800Z...DISSIPATED $$ Forecaster Berg
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