Guidance from recent runs of the Global Forecasting System (GFS) model indicate that a tropical cyclone could form southwest of Mexico during the next few days.  A tropical wave will move into the Eastern North Pacific Ocean south of Mexico.  The wave will move over water where the Sea Surface Temperature is between 29°C and 30°C.  Vertical wind shear caused by an upper low near the west coast of Mexico will initially inhibit development of the wave.  The GFS model is forecasting that the tropical wave will move into a region where the upper level winds are light and there will not be much vertical wind shear.  If that scenario occurs then a tropical cyclone could develop during the weekend near latitude 10°N and longitude 105°W.

If a tropical cyclone forms, a ridge of high pressure to the north of the cyclone would likely steer it in a generally west-northwesterly direction which would move it away from Mexico.  The environment would be favorable for intensification.  Rapid intensification may be possible and the system could become a major hurricane next week.

The development of this tropical wave could also be a signal that the Eastern North Pacific is getting active.  Although it has been a bit of a slow start to the hurricane season in that basin, the formation of a hurricane during the next week or so would be consistent with the long term climatology for that region.