ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Hurricane Aletta Discussion Number 15 NWS National Hurricane Center Miami FL EP022018 300 AM MDT Sat Jun 09 2018 Aletta's cloud pattern has continued to gradually degrade overnight. The eye is no longer apparent in infrared satellite pictures and the overall cloud pattern has become less symmetric due to the effects of southerly wind shear. Recent microwave imagery also shows that the southwestern portion of the inner core has eroded and most of the convective banding is located over the northeastern portion of the circulation. Subjective and objective Dvorak T-numbers have decreased and a blend of the Final-T and CI-numbers yields an initial intensity estimate of 95 kt. Aletta should continue to weaken during the next day or two as the vertical wind shear increases and the cyclone moves over gradually decreasing sea surface temperatures. These conditions are expected to cause a rapid decrease in intensity during the next 24 to 36 h. After that time, Aletta is forecast to move over SSTs below 26 degrees Celsius and into a less favorable thermodynamic environment, which should result in a continued spin down and degeneration of the system to a remnant low within 72 hours. The intensity guidance is in fairly good agreement and the NHC intensity forecast is close to the ICON consensus. The initial motion estimate remains 285/5 kt. There has been no significant change to the track forecast reasoning since the previous advisory. Aletta should continue to move around the southwestern portion of a mid-level ridge over northwestern Mexico during the next day or so. After Aletta weakens and becomes a more vertically shallow system, it should turn westward, then southwestward in the low-level trade wind flow. The overall guidance envelope has once again shifted southward and the updated NHC track forecast has been moved in that direction to be closer to the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 16.2N 112.7W 95 KT 110 MPH 12H 09/1800Z 16.6N 113.5W 80 KT 90 MPH 24H 10/0600Z 17.0N 114.6W 60 KT 70 MPH 36H 10/1800Z 17.2N 115.6W 45 KT 50 MPH 48H 11/0600Z 17.2N 116.9W 35 KT 40 MPH 72H 12/0600Z 17.0N 119.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 13/0600Z 16.6N 120.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 14/0600Z 16.0N 121.8W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown NNNN
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