Tropical Depression Six-E Discussion Number 2

Wiki-Hurricanes Forecast Center

800 PM PDT Wed Jun 27 2018

Six-E is gradually becoming better organized. Convection is developing closer to the center, and additional banding features are becoming established within the storm’s western semicircle. Latest satellite classifications were T1.5/25kt from SAB and T2.1/31kt from UW-CIMSS ADT, so the initial intensity has been nudged upward to 30 kt. Hopefully an ASCAT pass around 5z gives us a better understanding of the storm’s organization.

The depression continues to move swiftly west-northwest, and the initial motion estimate is 285/13. A mid-level ridge over northwestern Mexico extending into the eastern Pacific is steering the cyclone, and this should be the primary steering mechanism for the next several days. After 72 hours, a cut-off low moving southwest should provide an opportunity for Six-E to briefly take on a more poleward trajectory. However, given its expected weakening and degeneration to a remnant low by the end of the period, easterly trade winds should direct the system back west.

Moderate easterly wind shear around 15 kt continues to plague the depression given its current satellite appearance. This shear is expected to lessen over the coming days, but this trend will likely be negated by a steady decline in sea surface temperatures, as well as the potential for dry air entrainment. Most guidance – the LGEM, ECMWF, FV3-GFS, and HWRF – continue to show a weak to moderate tropical storm at peak. The GFS, which it should be mentioned is the best-performing model thus far in the season, makes Six-E a strong Category 1 hurricane within 72 hours. However, this appears unlikely and a symptom of an unrealistically intense simulated convective appearance over the next few hours. The intensity forecast has been nudged upward to better match 0z guidance.


INIT  28/0300Z 30 KT  35 MPH

 12H  28/1200Z 35 KT  40 MPH

 24H  29/0000Z 40 KT  45 MPH

 36H  29/1200Z 45 KT  50 MPH

 48H  30/0000Z 50 KT  60 MPH

 72H  01/0000Z 45 KT  50 MPH

 96H  02/0000Z 35 KT  40 MPH

120H  03/0000Z 25 KT  30 MPH...POST-TROP/REMNT LOW

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