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HURRICANE SIMON DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP192014
200 PM PDT SAT OCT 04 2014


A NOAA Hurricane Hunter Aircraft, carrying meteorologists from the
Meteorological Service of Mexico, reports that Simon has become a
major hurricane.  The aircraft measured 700 mb flight-level winds of
114 kt, and the Stepped Frequency Microwave Radiometer estimated
surface winds of 104 kt.  The minimum reported pressure was 950 mb
inside a 7 n mi wide eye.  Based on this information, the initial
intensity is increased to 105 kt.

The initial motion is 295/12.  Simon is expected to move generally
northwestward for the next 24-36 hours or so as is approaches a
weakness in the subtropical ridge to its north.  After that, the
system is expected to turn northward and northeastward.  There have
been some changes in the track guidance since the last advisory.
The ECMWF and Canadian models have shifted to the right and show a
faster northward motion, with the ECMWF now calling for landfall on
the Baja California peninsula in about four days.  The GFS, NAVGEM,
and the GFDL continue show Simon moving quickly to the northeast,
with the GFS forecasting landfall on the Baja California peninsula
in about three days.  The new forecast track has not changed much in
direction since the last advisory, but it has a faster forward
speed. That being said, the new forecast is still slower than the
consensus models, and additional adjustments to the speed could be
required on later advisories.

A combination of microwave imagery and aircraft data suggest that
Simon is about to start an eyewall replacement cycle.  Some
additional strengthening could occur in the next few hours before
the eyewall replacement and decreasing sea surface temperatures end
intensification.  A weakening trend should begin after 12 hours due
to the cooler water, and this trend should accelerate after 36 hours
as the cyclone encounters increasing shear and a very dry air mass.
The new intensity forecast follows the trend of the previous
forecast in making Simon a remnant low by the end of the forecast
period.  An alternative scenario is that Simon could make landfall
in Mexico as a weakening tropical cyclone if it moves as fast as the
GFS is forecasting.

Simon is the eighth major hurricane of the 2014 Eastern North
Pacific Hurricane season.  This ties the record for major
hurricanes set in 1983, 1992, and 1993.


FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 20.6N 115.0W  105 KT 120 MPH
 12H  05/0600Z 21.5N 116.4W  105 KT 120 MPH
 24H  05/1800Z 22.7N 117.4W  100 KT 115 MPH
 36H  06/0600Z 23.5N 117.6W   85 KT 100 MPH
 48H  06/1800Z 24.1N 117.6W   75 KT  85 MPH
 72H  07/1800Z 25.5N 117.0W   50 KT  60 MPH
 96H  08/1800Z 26.5N 116.0W   35 KT  40 MPH
120H  09/1800Z 27.5N 115.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven

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