Tropical Depression Six-E Discussion Number 1

Wiki-Hurricanes Forecast Center

200 PM PDT Wed Jun 27 2018

The area of low pressure centered about 600 miles south-southwest of Manzanillo, Mexico, has become sufficiently organization to be designated a tropical depression. The newly-formed cyclone is not particularly well organized at the current time, with most convection weighted to the west of its center. The initial intensity is set at 25 kt in accordance with earlier ASCAT data and a T1.5 classification from TAFB.

The depression is moving swiftly west-northwest and the initial motion estimate is 290/15. A weak mid-level ridge over northwestern Mexico is shifting into the eastern Pacific waters, which should keep the system on a west-northwest heading for the next 36 hours. Thereafter, a cut-off low is expected to dig southward from California and erode the eastern periphery of a larger mid-level ridge extending across the open Pacific. This low should continue to drift southwest in the medium range and direct the depression on a slightly more poleward course.

The environment over the next few days is not particularly conducive for development. CIMSS maps and model guidance analyzes moderate easterly wind shear of 15-20 kt near Six-E, and these upper-level winds are only forecast to gradually slacken over the next 96 hours. In the meantime, ocean temperatures are expected to fall from 29C to under 27C by 48 hours, and further decrease to near 23C by the end of the forecast period. Both the GFS and ECMWF barely show the depression attaining tropical storm strength, while the HWRF and LGEM depict a low-end tropical storm, and the SHIPS forecasts a strong tropical storm. Given the broad nature of the cyclone currently, as well as the marginally favorable environment, the forecast calls for Six-E to attain tropical storm strength by 36 hours and began to weaken after 72 hours. Degeneration to a remnant low is likely by the end of the period.


INIT  27/2100Z 25 KT  30 MPH

 12H  28/0600Z 30 KT  35 MPH

 24H  28/1800Z 30 KT  35 MPH

 36H  29/0600Z 35 KT  40 MPH

 48H  29/1800Z 40 KT  45 MPH

 72H  30/1800Z 35 KT  40 MPH

 96H  01/1800Z 30 KT  35 MPH...POST-TROP/REMNT LOW

120H  02/1800Z 25 KT  30 MPH...POST-TROP/REMNT LOW