270 
 WTPZ45 KNHC 280258
 TCDEP5
 
 Hurricane Rosa Discussion Number  12
 NWS National Hurricane Center Miami FL       EP202018
 800 PM PDT Thu Sep 27 2018
 
 Rosa has continued to rapidly intensify during the past several
 hours, with a distinct and warm eye noted on satellite images along
 with deep eyewall convection.  A blend of the latest Dvorak
 estimates gives an initial wind speed estimate of 125 kt, making
 Rosa the seventh category 4 hurricane of the very busy 2018 eastern
 Pacific hurricane season.  It is worth noting that this value ties
 2015 for the highest observed seasonal total in the basin during
 the satellite era.
 
 The hurricane still has a chance to intensify further given that it
 is still over warm waters within light shear.  By the weekend,
 however, Rosa will encounter more marginal SSTs, and the shear
 will likely increase.  These conditions should cause a significant
 weakening of the hurricane by early next week, and for Rosa to fall
 back to a tropical storm by Tuesday.  The intensity forecast isn't
 particularly confident at long range because of the possibility of a
 trough interaction somewhat offsetting the effects of cool eastern
 Pacific waters and dry stable air.  So far the guidance is fairly
 consistent, and the forecast continues to show steady weakening as
 Rosa approaches Baja California.
 
 Rosa continues moving at 265 deg, now at 8 kt.   A mid-level ridge
 over the southwestern United States is forecast to weaken and move
 eastward over the next couple of days as a mean mid-tropospheric
 trough forms near the west coast of the US.  This synoptic pattern
 should cause the tropical cyclone to gradually turn northward over
 that time, and eventually move to the northeast due to Rosa getting
 caught up into southwestern flow ahead of the trough.  While there
 are still some notable speed differences in the model guidance, the
 overall trend is for a faster solution, which is consistent with a
 more vertically deep system feeling the stronger mid-level flow.
 The model consensus continues the faster trend, and the new
 forecast follows suit.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  28/0300Z 16.9N 116.7W  125 KT 145 MPH
  12H  28/1200Z 17.1N 117.7W  130 KT 150 MPH
  24H  29/0000Z 17.8N 118.4W  125 KT 145 MPH
  36H  29/1200Z 19.0N 118.8W  115 KT 130 MPH
  48H  30/0000Z 20.9N 118.8W  100 KT 115 MPH
  72H  01/0000Z 25.0N 118.0W   75 KT  85 MPH
  96H  02/0000Z 29.0N 115.5W   45 KT  50 MPH
 120H  03/0000Z 36.0N 110.5W   25 KT  30 MPH...POST-TROP/INLAND
 
 $$
 Forecaster Blake
 
 

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