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Hurricane NORMAN


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Hurricane Norman Discussion Number  14
NWS National Hurricane Center Miami FL       EP162018
800 AM PDT Fri Aug 31 2018

Norman appears to be undergoing an eyewall replacement cycle.
Although a lack of earlier microwave imagery hasn't helped to
support this speculation, enhanced infrared BD-Curve images,
however, revealed a collapse of the inner core in the northeast
quadrant several hours ago.  Currently, that portion of the
eyewall has begun to fill in with a solid ring completely
surrounding the eye, albeit, rather thin.  Consequently,
subjective and objective T-numbers, as well as an earlier SATCON
analysis, support a slight decrease of the initial intensity to 115
kt.

Further slow weakening is forecast through the entire period,
although there could be fluctuations in the short-term due to the
aforementioned inner core structure evolution.  There also appears
to be some modest northeasterly shear impinging the northeast
portion of the cyclone, which could hamper strengthening. The Decay
SHIPS intensity model indicates that the shear will persist during
the next couple of days.  Through the remaining part of the
forecast, decreasing SSTs and the intrusion of a more stable/drier
environment from the north should lead to further weakening.  The
NHC forecast is similar to the previous one, and follows the
NOAA-HCCA and IVCN intensity consensus models.

The initial motion is estimated to be west-southwest, or 245/7 kt.
The cyclone's motion is currently influenced by a
northeast-southwest oriented mid-to-upper tropospheric ridge
residing between Hurricane Miriam to the west, and Norman to the
east. This current motion is expected to continue for
the next 36 hours, or so.  Afterward, the ridge between the two
tropical cyclones is expected to weaken as Miriam continues on a
generally northward track.  This change in the synoptic steering
pattern should cause Norman to turn to the west and then
west-northwest with an increase in forward speed.  The official
forecast has changed little over the past 6 hours and is based on a
blend of the HCCA and TVCN consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT  31/1500Z 16.7N 120.8W  115 KT 130 MPH
 12H  01/0000Z 16.4N 122.0W  105 KT 120 MPH
 24H  01/1200Z 16.2N 123.8W  100 KT 115 MPH
 36H  02/0000Z 16.3N 125.9W   95 KT 110 MPH
 48H  02/1200Z 16.8N 128.6W   90 KT 105 MPH
 72H  03/1200Z 18.3N 134.4W   80 KT  90 MPH
 96H  04/1200Z 19.5N 140.0W   70 KT  80 MPH
120H  05/1200Z 20.5N 144.0W   60 KT  70 MPH

$$
Forecaster Roberts

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