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Hurricane Norman Discussion Number  20
NWS National Hurricane Center Miami FL       EP162018
800 PM PDT Sat Sep 01 2018

Norman looked a little ragged in satellite imagery near 0000 UTC.
Since that time, though, the hurricane looks better organized, with
the eyewall convection better defined in visible and infrared
imagery.  Satellite intensity estimates have changed little since
the past advisory, so the initial intensity remains a possibly
generous 90 kt.

The initial motion is now 280/11.  The hurricane is expected to be
steered by a strong deep-layer subtropical ridge to the north,
resulting in a generally west-northwestward motion with an increase
in forward speed during the next 2-3 days.  After that time, a
decrease in forward speed is expected as Norman approaches a
weakness in the ridge.  There is some spread in the guidance at
days 4-5, with the HWRF on the north side of the guidance envelope
showing a northwestward turn and the GFS on the south side showing a
more westward motion.  The new forecast track is similar to the
previous track and lies just to the south of the center of the
guidance envelope.

Norman is expected to be in a light shear environment for 48-72 h.
However, during this time the cyclone will be moving over cooler
sea surface temperatures and into a drier air mass.  Based on the
guidance, the intensity forecast calls for little change in
strength for 24 h followed by a gradual weakening from 24-72 h.
After 72 h, increasing southerly shear should cause a faster
weakening.  It should be noted that there is a chance that Norman
could get stronger than forecast while over warm water during the
next 12-18 h as indicated by the HWRF and HMON models.

FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 16.7N 126.0W   90 KT 105 MPH
 12H  02/1200Z 17.1N 128.3W   90 KT 105 MPH
 24H  03/0000Z 18.0N 131.4W   90 KT 105 MPH
 36H  03/1200Z 18.9N 134.7W   85 KT 100 MPH
 48H  04/0000Z 19.8N 137.8W   80 KT  90 MPH
 72H  05/0000Z 21.0N 143.5W   70 KT  80 MPH
 96H  06/0000Z 21.5N 147.5W   60 KT  70 MPH
120H  07/0000Z 23.0N 150.5W   55 KT  65 MPH

$$
Forecaster Beven

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