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Hurricane NORMAN


Hurricane Norman Discussion Number  21
NWS National Hurricane Center Miami FL       EP162018
200 AM PDT Sun Sep 02 2018

Norman's structure has continued to slowly improve this morning.  A
ragged, but fairly clear, eye has been apparent in shortwave and
longwave IR imagery for the past several hours, and cloud tops
around the eye have generally cooled.  The initial intensity has
been held at 90 kt, in agreement with the latest Dvorak fixes from
TAFB and SAB.  However, the most recent objective intensity
estimates from the UW-CIMSS ADT are slightly higher, suggesting this
estimate could be conservative.

Given that Norman appears to be on the upswing, the forecast now
allows for some slight re-strengthening over the next 12 h while the
hurricane remains over warm waters and the shear is expected to be
light.  Beyond that time, however, there has been no significant
change to the intensity forecast reasoning or the guidance.  The
cyclone is still expected to gradually weaken as it encounters a
marginal environment consisting of cool SSTs, fairly dry air, and by
the end of the forecast period, increasing shear.  At 24 h and
beyond, the NHC forecast is very close to the intensity consensus,
and has not been substantially changed from the previous advisory.

Norman is beginning to accelerate and the initial motion estimate is
290/11.  A strong deep-layer subtropical ridge to the north should
keep Norman moving generally westward to west-northwestward through
most of the forecast period, with a notable increase in speed for
the next day or two.  All of the models agree on this general
scenario, however there is still some north-south spread in the
guidance, with the GFS and ECMWF on opposite sides of the guidance
envelope.  Like the previous forecast, the official track forecast
generally splits these models and lies near the middle of the
guidance envelope and the consensus aids, FSSE and HCCA.


INIT  02/0900Z 17.1N 127.5W   90 KT 105 MPH
 12H  02/1800Z 17.7N 129.8W   95 KT 110 MPH
 24H  03/0600Z 18.6N 133.0W   90 KT 105 MPH
 36H  03/1800Z 19.4N 136.3W   85 KT 100 MPH
 48H  04/0600Z 20.1N 139.7W   80 KT  90 MPH
 72H  05/0600Z 20.8N 144.6W   70 KT  80 MPH
 96H  06/0600Z 21.5N 149.0W   65 KT  75 MPH
120H  07/0600Z 23.0N 152.0W   60 KT  70 MPH

Forecaster Zelinsky