000 WTPZ43 KNHC 131457 TCDEP3 Tropical Storm Bud Discussion Number 16 NWS National Hurricane Center Miami FL EP032018 900 AM MDT Wed Jun 13 2018 Bud has continued to rapidly weaken due to significant upwelling of colder water beneath the cyclone, resulting in a pronounced erosion of the deep convection in the inner-core region. Sea-surface temperature data from U-Miami RSMAS indicate that Bud has churned up a cold wake that is least 3 deg C cooler than the surrounding ocean temperatures. The initial intensity of 55 kt is based on average of T- and CI-numbers from TAFB and SAB. Bud has been wobbling slowly about a north-northwestward track of about 340/04 kt for the past 12 h, and that is the motion used for this advisory. A deep-layer ridge located over the southwestern United States that has been partly blocking Bud's poleward trek is expected to slowly weaken and shift eastward during the next 72 h, giving way to an approaching mid-latitude trough. The increasing southerly flow between the ridge and the approaching trough will gradually induce a more northward component of motion by Thursday, followed by a turn toward the north-northeast on Friday. No change has been made to the previous NHC track forecast, and the new advisory is similar to the previous one and lies along the eastern edge of the model guidance envelope. Now that Bud has weakened to a tropical storm, significant upwelling beneath the cyclone should abate somewhat. However, Bud will be moving over sub-26C SSTs within the next 6-12 h, which will act to keep the atmosphere only marginally conducive for the formation of significant convection despite the vertical wind shear remaining quite favorable at only around 5 kt. A gradual spin down of Bud's circulation is expected until landfall occurs on southern Baja California Sur, followed by more significant erosion of the wind field on Friday due to cyclone interacting with the mountainous terrain of Baja California Sur and northwestern Mexico. The new intensity forecast is similar to the previous advisory and the Decay-SHIPS intensity model, and is slightly below the intensity consensus models. Despite Bud's expected weakening, the cyclone is still anticipated to be a tropical storm when it reaches southern Baja California Sur in 36-48 hours. Bud's remnant moisture plume is expected to spread northward and northeastward into northwestern Mexico and the U.S. Desert Southwest over the weekend, resulting in significant rainfall and possible flash flooding across those areas. For further information on the heavy rainfall threat, please see products issued by your local weather service office. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 19.4N 108.8W 55 KT 65 MPH 12H 14/0000Z 20.1N 109.0W 45 KT 50 MPH 24H 14/1200Z 21.1N 109.4W 40 KT 45 MPH 36H 15/0000Z 22.4N 109.7W 35 KT 40 MPH 48H 15/1200Z 24.2N 109.9W 35 KT 40 MPH 72H 16/1200Z 29.3N 109.4W 25 KT 30 MPH...POST-TROP/INLAND 96H 17/1200Z 35.5N 106.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 18/1200Z...DISSIPATED $$ Forecaster Stewart