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Hurricane Sergio Discussion Number  40
NWS National Hurricane Center Miami FL       EP212018
200 AM PDT Tue Oct 09 2018

Sergio's cloud pattern has changed little in the past 6 hours and is
comprised of a fragmented, large outer ring, about 100 n mi in
diameter.  The coldest cloud tops are now confined to just the
southeast portion of cyclone's circulation.  The Dvorak satellite
intensity estimates from TAFB and SAB support maintaining the
initial intensity at 75 kt.

Some slow weakening, or possibly very little change in strength, is
expected during the next 36 hours as Sergio traverses marginally
conducive oceanic temperatures and remains in a low shear
surrounding environment.  Afterward, the cyclone should enter a
region of much cooler sea surface temperatures and increasing
southwesterly shear, which should influence significant weakening
and reducing Sergio to a tropical storm prior to landfall.  Sergio
is forecast to move inland over Baja California Sur on Friday and
into the northwestern Mexico state of Sonora early Saturday.  At
the end of the forecast period, Sergio is expected to further
degenerate into a remnant low over the southwestern United States.
The intensity forecast is weighed heavily on the NOAA-HCCA and the
GFS and ECMWF global models which show Sergio making landfall as a
tropical storm.

Moisture associated with the remnants of Sergio is expected to
affect northwestern Mexico and portions of the southwest United
States over the weekend and could potentially cause heavy rainfall
in this region.  For more information about this potential hazard,
see products from the Weather Prediction Center and your local NWS
forecast office.

The initial motion is estimated to be northeastward, or 050/5 kt.
Sergio should begin accelerating in the aforementioned direction
this morning, and approach the central Baja California peninsula in
about 3 days.  There is high confidence in the forecast track as the
available global and regional models are clustered tightly together
through day 5.  The NHC forecast lies in the middle of the guidance
cluster and is close to the TVCN/HCCA consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT  09/0900Z 16.3N 127.9W   75 KT  85 MPH
 12H  09/1800Z 16.7N 127.1W   70 KT  80 MPH
 24H  10/0600Z 17.6N 125.4W   65 KT  75 MPH
 36H  10/1800Z 18.8N 123.2W   65 KT  75 MPH
 48H  11/0600Z 20.7N 120.7W   60 KT  70 MPH
 72H  12/0600Z 25.1N 114.9W   50 KT  60 MPH
 96H  13/0600Z 30.0N 108.4W   35 KT  40 MPH...INLAND
120H  14/0600Z 36.3N  97.9W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Roberts

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