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Hurricane Rosa Forecast Discussion Number 14
2018-09-28 17:18:13| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Fri Sep 28 2018 903 WTPZ45 KNHC 281517 CCA TCDEP5 Hurricane Rosa Discussion Number 14...Corrected NWS National Hurricane Center Miami FL EP202018 800 AM PDT Fri Sep 28 2018 Corrected typo in second paragraph. Cloud tops surrounding the distinct eye of Rosa have warmed considerably over the past few hours. A recent SSMI overpass showed a distinct double eyewall structure, and this is likely the reason for the degradation of Rosa's appearance. Dvorak intensity estimates from TAFB and SAB have decreased as a result, and the initial intensity has been therefore decreased to 120 kt. Given the continued warming of cloud tops since 1200 UTC, it is possible that Rosa has weakened a little more than this. Since an eyewall replacement cycle is ongoing, Rosa is no longer expected to intensify. In the short term, some additional weakening is likely, typical of major hurricanes undergoing eyewall replacements. If this process completes within the next 24 hours, there will be some opportunity for the hurricane to re-intensify while the shear is low and the hurricane remains over warm SSTs. However, steady weakening is anticipated beginning Saturday night since the cyclone is forecast to cross over much cooler SSTs. By 96 h, a weaker Rosa will likely approach the northern west coast of the Baja California peninsula and the resulting interaction with land will likely cause the cyclone to dissipate. It is worth noting that a farther northwest track would likely result in Rosa weakening faster than currently indicated, while a farther southeast track could allow Rosa to maintain a slightly stronger circulation as it crosses the northern Gulf of California. Rosa has begun its long-anticipated turn toward the northwest, and the initial motion estimate is 315/6 kt. The track models remain in good agreement that Rosa will gradually turn toward the north, and then north-northeast over the next few days ahead of an approaching mid- to upper-level trough to the northwest. No significant changes were made to the official track forecast, but it has been adjusted slightly to the left (or northwest) at most times, in line with the latest consensus guidance. Even though the NHC forecast calls for the surface circulation of Rosa to dissipate after making landfall along the northern Baja California coast, its associated moisture is expected to spread northeastward through parts of the southwest United States. For more information about potential rainfall in that area, please see products from the Weather Prediction Center and your local NWS forecast office. FORECAST POSITIONS AND MAX WINDS INIT 28/1500Z 17.2N 117.5W 120 KT 140 MPH 12H 29/0000Z 17.8N 118.1W 110 KT 125 MPH 24H 29/1200Z 19.2N 118.6W 105 KT 120 MPH 36H 30/0000Z 21.0N 118.9W 95 KT 110 MPH 48H 30/1200Z 23.0N 118.8W 80 KT 90 MPH 72H 01/1200Z 26.7N 117.4W 55 KT 65 MPH 96H 02/1200Z 31.6N 115.0W 35 KT 40 MPH...INLAND 120H 03/1200Z...DISSIPATED $$ Forecaster Zelinsky
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