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Tropical Storm ALETTA
ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm Aletta Discussion Number 6 NWS National Hurricane Center Miami FL EP022018 300 AM MDT Thu Jun 07 2018 The cloud pattern has become a little better organized and the low-level center appears to be more embedded within the deep convection than several hours ago. Although the outflow is fair, there are still shear at some level affecting the cyclone by observing the motion of the cirrus clouds. T-numbers from all agencies including the UW-CIMSS objective values have increased to 3.5 on the Dvorak scale, so the initial intensity has been increased to 55 kt. Guidance suggests some modest intensification, although there is a difference between the GFS-based SHIPS model and the ECMWF-based one. The latter is less aggressive and barely forecast Aletta to become a hurricane. The NHC follows the intensity consensus and the FSU super-ensemble, and calls for Aletta to become a hurricane within the next 12 to 24 hours. After 3 days, the environment becomes unfavorable and a gradual weakening should then begin. Aletta is moving toward the west or 280 degrees at about 6 kt around the periphery of a subtropical ridge over Mexico. This pattern should continue to steer the cyclone on a general westward course for a day or two, and then the cyclone sould turn to the west-northwest or northwest toward a weakness of the ridge. The NHC forecast is very close to the FSU super-ensemble, and is in the middle of the wide guidance envelope bounded by the GFS to the north and the ECMWF to the south. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 14.6N 109.2W 55 KT 65 MPH 12H 07/1800Z 14.7N 110.0W 65 KT 75 MPH 24H 08/0600Z 14.9N 111.0W 70 KT 80 MPH 36H 08/1800Z 15.3N 111.7W 75 KT 85 MPH 48H 09/0600Z 15.7N 112.5W 75 KT 85 MPH 72H 10/0600Z 17.0N 114.0W 65 KT 75 MPH 96H 11/0600Z 18.0N 116.0W 45 KT 50 MPH 120H 12/0600Z 18.0N 117.5W 30 KT 35 MPH $$ Forecaster Avila NNNN