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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 dats indicate that Orlene
is drifitng northward or 360/01 kt. The cyclone is expected to
remain nearly stationary overnight, embedded within a large dreak 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 expected to steadily stengthen,
forcing the cyclone on a general westward direction and at a much
faster forward speed. The new forecast track is again similar to
the previous track and lies near the center of the cluster of the
consensus and
dynamical models.

Orlene is experiencing 15-20 kt of southwesterly vertical wind
shear, and this is likely to continue for about another 24 hours.
After that time, the dynamical models forecast the shear to decrease
while the cyclone moves near and parallel to the 26C sea surface
temperature isotherm.  These conditions, combined with abundant dry
air seen west of the cyclone in water vapor imagery, should lead to
gradual weakening through the forecast period.  The new intensity
forecast is an again an update of the previous forecast, and it lies
near the upper edge of the envelope of intensity guidance.



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

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