697 
 WTPZ45 KNHC 271454
 TCDEP5
 
 Hurricane Rosa Discussion Number  10
 NWS National Hurricane Center Miami FL       EP202018
 800 AM PDT Thu Sep 27 2018
 
 Rosa is becoming better organized.  Conventional satellite imagery
 show a large area of cold cloud tops near the center, and there is
 a hint of an eye in the first-light visible images.  Microwave
 imagery indicates that the eye structure underneath the overcast
 has become better defined, with less evidence of dry air entrainment
 than seen yesterday.  The initial intensity has been increased to
 90 kt in best agreement with the subjective Dvorak estimate from
 TAFB and the CIMSS ADT technique.  The hurricane currently has good
 outflow in all directions.
 
 Conditions appear generally favorable for continued strengthening
 for the next 24-36 hr, and the new intensity forecast now makes Rosa
 a major hurricane in 12 h.  It should be noted that if the current
 strengthening is the start of the previously anticipated rapid
 intensification Rosa could get stronger than the current forecast,
 which shows a peak intensity of 105 kt near the upper edge of the
 intensity guidance.  After 36 h, the forecast track takes the
 cyclone over decreasing sea surface temperatures, and by the end of
 the forecast period it is expected to encounter strong southwesterly
 vertical shear.  This combination should cause significant
 weakening, and Rosa is expected to be a tropical storm as it
 approaches the Baja California peninsula near the end of the
 forecast period.
 
 The initial motion is a somewhat uncertain 270/10.  For the next
 12-24 h, the hurricane should move generally westward on the south
 side of the subtropical ridge over the Pacific west of northern
 Mexico and a mid-latitude ridge over California.  Subsequently, Rosa
 should turn northwestward and northward through a break in the ridge
 caused by a large mid-latitude trough moving eastward through the
 northeastern Pacific.  By 96-120 h, Rosa should recurve
 northeastward into the westerlies on the eastern side of the trough
 and move in the general direction of northwestern Mexico and the
 northern Baja California peninsula.  There remains some spread in
 the guidance forward speed after recurvature, with the GFS being
 faster than the ECMWF.  The new intensity forecast is a blend of
 these extremes in forward speed at the 96 and 120 h points.
 Overall, the guidance envelope has shifted a little west since the
 previous advisory, and the new track is also shifted a little
 westward.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  27/1500Z 17.2N 115.4W   90 KT 105 MPH
  12H  28/0000Z 17.3N 116.9W  100 KT 115 MPH
  24H  28/1200Z 17.5N 118.1W  105 KT 120 MPH
  36H  29/0000Z 18.3N 119.0W  105 KT 120 MPH
  48H  29/1200Z 19.5N 119.4W  100 KT 115 MPH
  72H  30/1200Z 22.5N 119.5W   80 KT  90 MPH
  96H  01/1200Z 26.0N 118.0W   60 KT  70 MPH
 120H  02/1200Z 29.5N 115.5W   40 KT  45 MPH
 
 $$
 Forecaster Beven