000
WTPZ41 KNHC 140249
TCDEP1

HURRICANE ORLENE DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP162016
800 PM PDT TUE SEP 13 2016

Microwave satellite imagery indicates that the inner-core convection
of Orlene has steadily degraded during the past 6 hours, with the
eyewall no longer closed. The eye briefly appeared in visible and
infrared imagery around 0000Z, but is not evident in conventional
satellite imagery. The initial remains at 75 kt based on consensus
subjective satellite estimates of T4.5/77 kt from TAFB and SAB.

The microwave and conventioanl satellite data indicate that Orlene
is drifting northward or 360/01 kt. The cyclone is expected to
remain nearly stationary overnight, embedded within a narrow break
in the subtropical ridge. A slow westward motion is expected to
begin by early Wednesday as a shortwave trough lifts out, allowing
the ridge to build back in to the north of Orlene in 12-24 hours.
After that time, the ridge is forecast to steadily stengthen,
forcing the cyclone on a general westward direction at a much faster
forward speed. The new forecast track is similar to the previous
advisory track, and lies close to the consensus model TVCN and a
beldn of the GFS and ECMWF model solutions.

Although moderate southwesterly vertical wind shear currently
affecting the cyclone is forecast to decrease to around 5 kt
throughout the forecast period, the cyclone will also be moving over
near 26 deg C SSTs and into a very dry and stable airmass. The
result sould be a gradual erosion of the inner-core convection,
causing the cyclone to slowly but steadily weaken. The new NHC
intensity forecast is similr to the previous intensity forecast, and
closley follows the SHIPS and LGEM intensity guidance, which is just
a little above the intensity consensus model IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 20.4N 118.6W   75 KT  85 MPH
 12H  14/1200Z 20.4N 119.0W   65 KT  75 MPH
 24H  15/0000Z 20.4N 120.0W   60 KT  70 MPH
 36H  15/1200Z 20.2N 121.7W   50 KT  60 MPH
 48H  16/0000Z 20.1N 123.9W   45 KT  50 MPH
 72H  17/0000Z 19.9N 128.7W   40 KT  45 MPH
 96H  18/0000Z 19.9N 133.4W   35 KT  40 MPH
120H  19/0000Z 20.8N 137.3W   30 KT  35 MPH

$$
Forecaster Stewart