201 
 WTPZ45 KNHC 020242
 TCDEP5
 
 Tropical Storm Rosa Discussion Number  28
 NWS National Hurricane Center Miami FL       EP202018
 800 PM PDT Mon Oct 01 2018
 
 Rosa continues to lack deep convection near the center, which is
 currently over sea surface temperatures of 21C.  However, strong
 convection is occurring to the northeast of the center over the
 northern Gulf of California and the adjacent land areas.  The
 Mexican automated station at Isla Cedros reported 30 kt winds with
 gusts near 40 kt a few hours ago, and passive microwave data
 suggests the strongest winds in the cyclone are currently moving
 onshore south of Punta Eugenia where no surface observations are
 available.  The initial intensity is kept at 35 kt, and it is
 possible that this is generous.  Rosa should weaken as it crosses
 Baja California, but it is likely the warm water of the Gulf of
 California will maintain the system as a tropical cyclone until
 final landfall in northwestern Mexico.  After that landfall, Rosa
 should quickly degenerate into a remnant low over the southwestern
 United States on Tuesday.
 
 The initial motion is 035/9. Rosa should move generally
 northeastward between a deep-layer ridge over northern Mexico and a
 mid- to upper-level trough over the northeastern Pacific until the
 cyclone dissipates.  The dynamical models suggests the possibility
 that the center of Rosa will reform over the Gulf of California in
 the next 12 h, which may lead to some erratic changes in the forward
 speed.
 
 
 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 affecting portions of the central
 and northern Baja California peninsula, 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  02/0300Z 28.9N 115.3W   35 KT  40 MPH
  12H  02/1200Z 30.8N 114.5W   25 KT  30 MPH
  24H  03/0000Z 33.5N 113.5W   15 KT  15 MPH...POST-TROP/INLAND
  36H  03/1200Z...DISSIPATED
 
 $$
 Forecaster Beven
 
 

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