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ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM 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 NNNN