Although the trough near the Bahamas did not develop into a tropical or subtropical cyclone, there is a strong model consensus that the first tropical cyclone of the 2018 Pacific hurricane season may form next week. An area of low pressure is expected to form over the open Pacific near 10°N 120°W, and this system will need to be watched for potential development next week as it moves west-northwestward or northwestward. The National Hurricane Center (NHC) has not yet mentioned this system in their Tropical Weather Outlook, but if current trends continue, I expect a mention by Monday.

Of the Saturday 12z model runs – the GFS, UKMET, and CMC models all predicted a weak tropical cyclone would form over the eastern Pacific far from land by next Thursday. The 12z Saturday ECMWF model run trended closer to the other models, predicting a weak closed surface low to develop in the same area. None of the models predicted the system would become a hurricane. Wind shear is expected to be low to moderate, and sea surface temperatures are near 28°C (82.4°F).

It should be noted that if this system forms into a tropical cyclone, it would be unusually far west for a May tropical cyclone in the East Pacific basin. If this system becomes a tropical storm (winds of at least 34 knots/39 mph), it would be named Aletta. I give this system a 40% chance of development within the next five days.

The Eastern Pacific hurricane season does not officially begin until May 15 – ten days from now. However, tropical cyclones may form before or after the season, but this is rather uncommon. Just last season, Tropical Storm Adrian became the earliest forming named storm in the Eastern Pacific proper when it formed on May 9. It does not appear likely that this system will beat Adrian’s record for earliest formation, but it cannot be ruled out entirely.