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Tropical Storm ALETTA
ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm Aletta Discussion Number 18 NWS National Hurricane Center Miami FL EP022018 900 PM MDT Sat Jun 09 2018 Aletta's downfall has been remarkable. All associated deep convection has dissipated due to 25 kt of southerly shear and marginally warm sea surface temperatures, leaving a swirl of low- to mid-level clouds. Dvorak estimates are falling as fast as they can based on rules, and the advisory intensity is being set at 50 kt. The latest SATCON numbers support this estimate. Aletta has been losing latitude through the day, moving west-southwestward since this morning. Recent satellite images seem to suggest that the cyclone is now moving westward, and the motion estimate is 270/6 kt. The dynamical and simpler Trajectory and Beta Models (TAB) have been insisting that Aletta will turn generally northwestward, but that obviously hasn't happened. The models seem to be assuming that Aletta is still producing convection, with the deeper modeled vortex being steered toward the northwest. With no deep convection, the shallow circulation is likely to continue generally westward or south of due west, and the NHC forecast is along the southern edge of the guidance, roughly between the ECMWF model and the skill-baseline Trajectory-CLIPER (TCLP) model. The new NHC intensity forecast now makes Aletta a remnant low in 36 hours, but if deep convection doesn't redevelop, that transition will occur on Sunday. Fast weakening is expected to continue, and the official forecast closely follows the HCCA model and the intensity consensus during the first 24-36 hours. After that, the remnant low's winds are based on the GFS and ECMWF forecast wind fields. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 15.9N 114.3W 50 KT 60 MPH 12H 10/1200Z 15.9N 115.2W 35 KT 40 MPH 24H 11/0000Z 15.9N 116.4W 30 KT 35 MPH 36H 11/1200Z 15.8N 117.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 12/0000Z 15.8N 118.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 13/0000Z 15.8N 120.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 14/0000Z 15.5N 121.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 15/0000Z 15.0N 121.5W 15 KT 15 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg NNNN