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Hurricane Rosa Discussion Number   9
NWS National Hurricane Center Miami FL       EP202018
300 AM MDT Thu Sep 27 2018

The cloud pattern is a little more impressive with plenty of deep
convection and a well-defined cyclonically-curved band south of the
center. There is no evidence of an eye yet in conventional
IR imagery.  Satellite intensity estimates from all agencies,
however, are unanimously 4.5 on the Dvorak scale, so the intensity
is kept at 75 kt.  Both atmospheric and oceanic conditions are
favorable for intensification with the possibility of rapid
strengthening within the next 12 to 24 hours, although intensity
guidance is not as aggressive as in earlier runs.  The NHC forecast
follows closely the intensity consensus and is very similar to the
previous one.  Beyond 3 days, Rosa should be over cooler waters, and
by the time it reaches the northern Baja California peninsula, the
cyclone should have weakened to a tropical storm.

Rosa is moving westward or 270 degrees at 10 kt steered by the deep
easterly flow around a subtropical ridge.  Rosa will soon reach
the southwestern edge of the high and will begin to move toward the
northwest and northward as an eastward moving mid-level trough
erodes the high to the north.  Rosa should then turn toward the
northeast ahead of the trough by the end of the forecast period.
This is the solution provided by most of the track models which all
turn the cyclone northward and then northeastward. The NHC forecast
is in the middle of the guidance envelope and is in between
the corrected consensus HCCA and the multi-model aids.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 17.1N 114.1W   75 KT  85 MPH
 12H  27/1800Z 17.2N 115.6W   90 KT 105 MPH
 24H  28/0600Z 17.5N 117.0W  100 KT 115 MPH
 36H  28/1800Z 17.8N 118.0W  105 KT 120 MPH
 48H  29/0600Z 18.8N 118.8W  105 KT 120 MPH
 72H  30/0600Z 22.0N 119.0W   90 KT 105 MPH
 96H  01/0600Z 25.5N 118.0W   60 KT  70 MPH
120H  02/0600Z 29.0N 116.0W   45 KT  50 MPH

$$
Forecaster Avila

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