je.st
news
Tropical Storm Rosa Forecast Discussion Number 25
2018-10-01 10:39:10| National Hurricane Center (East Pacific)
Issued at 200 AM PDT Mon Oct 01 2018 431 WTPZ45 KNHC 010839 TCDEP5 Tropical Storm Rosa Discussion Number 25 NWS National Hurricane Center Miami FL EP202018 200 AM PDT Mon Oct 01 2018 Convection has been steadily decreasing due to the combination of southwesterly shear of about 30 kt and cool SSTs of less than 24 deg C. As a result, only a small patch of thunderstorms remains in the northeastern quadrant of Rosa's circulation. ASCAT passes around 0414Z and 0516Z only indicated wind speeds of 41-42 kt in the eastern semicircle. Assuming that some undersampling is occurring, the intensity has only been decreased to 45 kt for this advisory. Additional weakening is expected due to a further increase in the vertical wind shear and decreasing ocean temperatures beneath the cyclone. The official intensity forecast calls for Rosa to be near 35 kt at the time of landfall later today, but it is possible that more weakening could occur than currently indicated. Regardless, strong tropical-storm-force wind gusts will be widespread across the higher elevations of the northern Baja California peninsula. Rosa is expected to become remnant low before the cyclone reaches Arizona due to the rugged terrain of Baja and northwestern Mexico, and the continued strong wind shear. Rosa is moving northeastward now, or 035/10 kt. A northeastward to north-northeastward motion is expected until and after landfall, with some acceleration beginning later tonight. The latest NHC model guidance remains tightly clustered, and the official forecast track lies close to the previous track and an average of the TVCE, HCCA, and FSSE multi-model consensus aids. Key Messages: 1. The main hazard expected from Rosa or its remnants is very heavy rainfall in Baja California, northwestern Sonora, and the U.S. Desert Southwest. These rains are expected to produce life-threatening flash flooding and debris flows in the deserts, and landslides in mountainous terrain. For more information about potential rainfall in that area, please see products from the Weather Prediction Center and your local NWS forecast office. 2. Tropical storm conditions are expected over portions of the central and northern Baja California peninsula later today, especially over higher elevations. These conditions could spread into the northern Gulf of California later tonight. Interests in those locations should monitor the progress of Rosa. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 26.7N 117.0W 45 KT 50 MPH 12H 01/1800Z 28.0N 116.1W 35 KT 40 MPH 24H 02/0600Z 30.1N 114.8W 30 KT 35 MPH...INLAND NRN BAJA CALIF 36H 02/1800Z 32.9N 113.5W 20 KT 25 MPH...POST-TROP/INLAND 48H 03/0600Z 35.9N 112.2W 15 KT 15 MPH...POST-TROP/INLAND 72H 04/0600Z...DISSIPATED INLAND $$ Forecaster Stewart
Tags: number
discussion
storm
rosa
Category:Transportation and Logistics