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ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Hurricane Aletta Discussion Number 12 NWS National Hurricane Center Miami FL EP022018 900 AM MDT Fri Jun 08 2018 The remarkable intensification of Aletta has continued through this morning. The eye has become clear and at times has been surrounded by a closed ring of cloud tops colder than -70 deg C. The initial intensity of 120 kt is based on a blend of subjective and objective Dvorak estimates. It is noteworthy that the intensity of Aletta has increased by an estimated 60 kt in just 24 hours since yesterday morning. The short-range intensity forecast is particularly difficult since there are no obvious reasons why Aletta should cease intensification. Although the deep-layer wind shear is currently very low and SSTs are warm enough to support further intensification, nearly all of the intensity guidance indicates that Aletta should have reached its peak. Recent microwave imagery does indicates that a secondary eyewall has not yet formed, however the resolution of the instruments could limit our ability to detect such a feature. Given the low bias of the guidance for Aletta so far, the new forecast allows for some slight additional strengthening during the day today. By 24 hours, moderate shear should cause the hurricane to begin weakening steadily, with rapid weakening occuring between 36 and 72 h while Aletta traverses a strong SST gradient. Due to the higher initial intensity of Aletta, the official forecast is a little higher than the previous one for the first 24 hours, but very similar thereafter. Almost no change has been to the track forecast. A broad upper-level trough over the eastern Pacific should cause Aletta to turn more toward the northwest in 24 to 36 h. After Aletta rapidly weakens over the weekend, the lower-level trade winds will become the dominant steering flow, forcing the cyclone to turn back toward the west. Excluding the ECMWF which does not have a realistic depiction of the major hurricane, the guidance has come into somewhat better agreement today and confidence in the track forecast has increased since yesterday. FORECAST POSITIONS AND MAX WINDS INIT 08/1500Z 15.8N 111.2W 120 KT 140 MPH 12H 09/0000Z 16.3N 111.9W 125 KT 145 MPH 24H 09/1200Z 17.0N 112.9W 110 KT 125 MPH 36H 10/0000Z 17.9N 113.8W 85 KT 100 MPH 48H 10/1200Z 18.6N 114.8W 65 KT 75 MPH 72H 11/1200Z 19.5N 116.7W 35 KT 40 MPH 96H 12/1200Z 20.0N 118.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 13/1200Z 20.0N 119.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Zelinsky NNNN