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HURRICANE ORLENE DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP162016
200 AM PDT TUE SEP 13 2016

Recent microwave images suggest that there has been some erosion of
the southern portion of the eyewall overnight, and the overall
satellite presentation of the hurricane has continued to gradually
degrade.  The eye has become cloud filled in infrared satellite
pictures and the convective tops surrounding the eye have warmed
overnight.  Despite the recent loss of organization, a blend of the
subjective and objective Dvorak T- and CI-numbers yields an initial
intensity estimate of 90 kt.  The leveling-off of Orlene's intensity
appears to have been caused by 15-20 kt of south-southwesterly shear
as diagnosed by a UW/CIMSS shear analysis.  The shear conditions are
not expected to change much today.  Meanwhile, Orlene is forecast to
move very slowly during the next 36 h, which is likely to cause
upwelling of cooler waters. These conditions are expected to cause
gradual weakening during the next day or so.  After that time, the
shear is expected to decrease, but less favorable thermodynamic
conditions are likely to continue to contribute to weakening. The
new NHC intensity forecast shows a little more weakening during the
next 2-3 days, but is close to the previous advisory thereafter.
This is in good agreement with the latest Florida State
Superensemble and close to the IVCN consensus model.

It appears that the hurricane is beginning to slow down as
anticipated, with an estimated initial motion of 360/4 kt.  Orlene
will be within an area of light steering currents during the next
day or so, and only a slow northward motion is anticipated today.
By Wednesday, a subtropical ridge to the north of the hurricane is
forecast to strengthen, which should begin to steer Orlene westward
at a faster rate of speed.  Near the end of the forecast period,
the models begin to diverge, with the latest GFS now taking a
stronger system more poleward, while the ECMWF shows a weaker Orlene
moving more westward.  Since this is a flip-flop in the models from
the previous runs, the NHC track maintains the more westward
solution, and is close to the GFS ensemble mean and the multi-model
consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0900Z 19.2N 118.9W   90 KT 105 MPH
 12H  13/1800Z 19.7N 118.9W   80 KT  90 MPH
 24H  14/0600Z 20.1N 119.0W   70 KT  80 MPH
 36H  14/1800Z 20.2N 119.7W   60 KT  70 MPH
 48H  15/0600Z 20.2N 121.1W   55 KT  65 MPH
 72H  16/0600Z 19.9N 125.6W   45 KT  50 MPH
 96H  17/0600Z 19.7N 130.5W   45 KT  50 MPH
120H  18/0600Z 20.0N 134.3W   40 KT  45 MPH

$$
Forecaster Brown

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