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Hurricane Norman Discussion Number  10
NWS National Hurricane Center Miami FL       EP162018
800 AM PDT Thu Aug 30 2018

Norman has rapidly strengthened during the past 12 to 24 hours,
with the development of a well-defined 20-nmi-wide eye and a thick
ring of cold cloud tops of -70 to -85C.  Dvorak constraints have
limited the amount of increase in the subjective and objective final
T-numbers, but the most recent raw data T-numbers are between T6.5
and T7.2, which yields an initial intensity estimate of 130 kt.
Norman's intensity has increased an estimated 70 kt from 1200 UTC
yesterday morning to 1200 UTC this morning- the fastest in the
basin since Patricia in 2015.  Norman has become the 5th category 4
hurricane in the eastern Pacific in 2018 and is also the strongest
hurricane in the basin so far this season.

The hurricane remains in a low-shear environment and will continue
to move over very warm waters of 29-30 degrees Celsius for another
24 hours.  These conditions are expected to allow for additional
strengthening and Norman is forecast to become a category 5
hurricane later today.  Eyewall replacement cycles are likely after
that time, which are difficult to predict, and should cause some
fluctuations in intensity during the next couple of days. Later in
the period, gradually decreasing sea surface temperatures and a
slight increase in shear are forecast to cause gradual weakening.
However, Norman is predicted to remain a hurricane throughout the
5-day forecast period.

Norman is moving westward or 270/7 kt. A strong subtropical ridge
that extends from the Baja California peninsula west-southwestward
into the eastern Pacific is expected to turn Norman
west-southwestward later today or tonight, with this motion
continuing over the next couple of days.  The global models shift
the orientation of the ridge in a few days which should cause
Norman to turn west-northwestward by early next week.  The
dynamical model guidance is tightly clustered, and the NHC track
forecast is close to the multi-model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT  30/1500Z 17.8N 118.0W  130 KT 150 MPH
 12H  31/0000Z 17.7N 119.1W  140 KT 160 MPH
 24H  31/1200Z 17.2N 120.7W  135 KT 155 MPH
 36H  01/0000Z 16.6N 122.3W  125 KT 145 MPH
 48H  01/1200Z 16.1N 124.1W  120 KT 140 MPH
 72H  02/1200Z 16.7N 128.0W  110 KT 125 MPH
 96H  03/1200Z 18.5N 133.2W   95 KT 110 MPH
120H  04/1200Z 20.2N 138.5W   70 KT  80 MPH

$$
Forecaster Brown

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