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Hurricane SIMON


800 AM PDT SUN OCT 05 2014

Simon continues to weaken.  The distribution of deep convection has
become more asymmetric during the last 12 hours, and there has been
a general warming of cloud top temperatures. The cyclone's cloud
canopy has also been expanding over the northern semicircle while
eroding some to the south.  This transformation of the cloud pattern
is primarily related to an increase in southwesterly shear over the
hurricane, as diagnosed by UW-CIMSS shear analyses and SHIPS model
output.  A blend of Dvorak Final-T and CI-numbers from TAFB and SAB
is used to reduce the initial intensity to 85 kt.

As Simon gains latitude during the next couple of days, a
further increase in shear is expected in association with a mid-
to upper-level shortwave trough several hundred miles west of the
coast of southern California.  The abrupt and substantial increase
in shear, combined with water temperatures around 25 deg C and other
considerably less conducive thermodynamic conditions, should result
in a rapid decay of the cyclone.  Global models show the low- to
mid-level centers of Simon decoupling around 48 hours, and Simon
should become a remnant low in 72 hours, if not sooner. The NHC
intensity forecast, like the previous one, shows rapid weakening
over the next 48 hours and is in excellent agreement with the latest
multi-model consensus.

The initial motion estimate is 325/09.  Simon is moving into a
region of weak steering on the western periphery of a subtropical
ridge centered near western Mexico.  This synoptic pattern should
result in the cyclone's gradual turning toward the north with a
decrease in forward speed over the next day or so.  The previously
mentioned shortwave trough should cause Simon to turn northeastward
within 48 hours, with Simon or its remnants likely moving over the
north-central portion of the Baja California peninsula later in the
forecast period.  The NHC forecast has not changed much relative to
the previous one and remains close to the multi-model consensus,
substantially slower than the GFS solution which brings Simon inland
over northwestern Mexico in 72 hours.

Even if Simon or its remnant circulation does not make it across the
rugged terrain of the Baja California peninsula, deep moisture
associated with the cyclone is expected to spread across the
northern Baja California peninsula, northwestern Mexico, and into
the U.S. Desert Southwest, which could trigger heavy rains in
those regions in a few days.


INIT  05/1500Z 22.9N 117.1W   85 KT 100 MPH
 12H  06/0000Z 23.6N 117.4W   70 KT  80 MPH
 24H  06/1200Z 24.5N 117.5W   55 KT  65 MPH
 36H  07/0000Z 25.4N 117.2W   40 KT  45 MPH
 48H  07/1200Z 26.2N 116.8W   30 KT  35 MPH
 72H  08/1200Z 28.2N 115.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  09/1200Z 29.7N 113.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  10/1200Z...DISSIPATED

Forecaster Kimberlain