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Tropical Storm Norman Forecast Discussion


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Tropical Storm Norman Discussion Number  47
NWS Central Pacific Hurricane Center Honolulu HI   EP162018
1100 AM HST Sat Sep 08 2018

Norman is quickly losing the characteristics of a tropical cyclone 
as strong vertical wind shear is taking its toll. The low-level 
circulation center (LLCC) has been exposed for the better part of a 
day now, with sporadic deep convection in the northern semicircle 
remaining well removed from the center. Visible satellite imagery 
shows the LLCC becoming increasingly elongated, now marked by a 90
nm X 30 nm wide clear area. Intensity estimates support lowering the
initial intensity to 45 kt for this advisory as Norman continues to
spin down.

The track forecast takes Norman generally toward the north through 
day 3 before briefly turning it northwestward before dissipation on 
day 5, in line with GFEX. It appears that Norman will still produce 
at least gale force winds for the next couple of days as it 
interacts with a developing cold-core low to its northwest, with
GFS indicating winds in excess of 50 kt in 24-36 hours. While this
seems a little extreme, the official intensity forecast indicates
little change in intensity through day 2, with gradual weakening
thereafter.

This will be the last advisory issued by CPHC on this system. 


FORECAST POSITIONS AND MAX WINDS

INIT  08/2100Z 26.9N 154.6W   45 KT  50 MPH
 12H  09/0600Z 28.4N 154.6W   40 KT  45 MPH...POST-TROPICAL
 24H  09/1800Z 30.2N 154.4W   40 KT  45 MPH...POST-TROPICAL
 36H  10/0600Z 32.0N 154.1W   40 KT  45 MPH...POST-TROPICAL
 48H  10/1800Z 33.5N 154.2W   35 KT  40 MPH...POST-TROPICAL
 72H  11/1800Z 35.0N 155.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  12/1800Z 35.5N 157.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  13/1800Z...DISSIPATED

$$
Forecaster Birchard

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