Localized flooding possible as two tropical storms form off Mexico
The eastern Pacific hurricane season is off to the races as Barbara and Cosme form off the coast of Mexico
Two tropical storms formed off the coast of Mexico this weekend, at least one of which could strengthen into the season’s first hurricane to kick off the new workweek.
Forecasters are tracking Tropical Storm Barbara and Tropical Storm Cosme as they swirl west of Mexico. Periods of heavy rain could lead to flooding and mudslides around some major tourist destinations.
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Barbara could become a hurricane
Hurricane season is in full swing across the eastern Pacific, and a favourable environment off the western coast of Mexico allowed two tropical storms to form this weekend.
Barbara is the healthiest of the two systems, developing into a solid tropical storm during the day Sunday. The system is close enough to land that its heavy rain could spread across Puerto Vallarta, Manzanillo, and Acapulco.
The U.S. National Hurricane Center (NHC) calls for widespread rainfall totals of 25-50 mm throughout the region, with totals of 50-100 mm possible toward Acapulco. Locally higher totals are possible, bringing along the risk for flash flooding and mudslides.
While the system is close enough to spread rain over land, the centre of the storm should remain safely out to sea. The NHC expects Barbara to briefly strengthen into a hurricane before gradually weakening through the middle of the week.
Tropical Storm Cosme formed to Barbara’s west on Sunday afternoon. Forecasters predict that the small system could approach hurricane strength before encountering cooler waters and drier air by the middle of the week, forcing the system to quickly weaken and fall apart.
Eastern Pacific season runs through November 30
Hurricane season in the eastern Pacific basin runs through the end of November.
NOAA’s seasonal outlook called for 12-18 named storms, with 5-10 of those systems growing into hurricanes, and 2-5 of those hurricanes achieving Category 3 status or stronger. This is close to the eastern Pacific’s seasonal average of 15 named storms, 8 hurricanes, and 4 major hurricanes.
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This season’s activity is influenced by the lack of El Niño and La Niña, as well as a negative phase of the Pacific Decadal Oscillation (PDO), a pattern that can lead to cooler-than-normal ocean temperatures. Cooler waters can suppress tropical cyclone development.
Most storms in the eastern Pacific head out to sea and don’t affect land. Those that do affect land frequently hit the mountainous communities of western Mexico, often triggering widespread flooding and mudslides.
Header satellite image courtesy of NOAA.