Barbara expected to weaken as eyes shift to the next Pacific disturbance
With Barbara expected to weaken soon and Cosme forecast to reach hurricane status shortly, another disturbance is likely to come to fruition in the East Pacific basin in the next several days, possibly as early as late this week or on the weekend
Two named storms formed off the coast of Mexico on the weekend, with Barbara strengthening and becoming the season’s first hurricane on Monday.
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As Hurricane Barbara holds steady, with weakening expected soon, and Tropical Storm Cosme anticipated to become a hurricane soon, environmental conditions appear conducive for gradual development of a new low-pressure system south of Mexico.
Forecasters give the new disturbance a high, or 70 per cent, chance of formation within the next seven days, likely coming to fruition by late week or on the weekend.
Barbara threatens large swells over southwestern Mexico
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.
Hurricane Barbara strengthened southwest of Mexico on Monday morning, marking the first hurricane of the 2025 season.
According to the U.S. National Hurricane Center (NHC), Barbara's maximum, sustained winds are currently near 120 km/h with higher gusts.
There are no coastal watches or warnings in effect, but swells generated by Barbara will affect portions of the coast of southwestern Mexico during the next few days.
"These swells are likely to cause life-threatening surf and rip current conditions," the NHC warns. "Please consult products from your local weather office."
The 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 weaken on Monday night before becoming a remnant low by Wednesday.
Tropical Storm Cosme likely to become a hurricane soon
Cosme formed to Barbara’s west on Sunday afternoon.
Forecasters predict that Cosme could become a hurricane by Monday night or early Tuesday morning, as additional strengthening is expected in the short range. Maximum sustained winds have increased to near 110 km/h, with higher gusts.
Rapid weakening is expected late Tuesday and Wednesday. Cosme will likely become a post-tropical low in a couple of days.
Eyes turn to next possible disturbance
An area of low pressure is forecast to develop later this week south of southern Mexico. Environmental conditions appear conducive for some gradual development of this system, and a tropical depression is likely to form late this week or over the weekend.
Formation chance through seven days is hight (70 per cent). If it becomes a named storm, it will take on the Dalila moniker.
Eastern Pacific season runs through Nov. 30
Hurricane season in the East Pacific 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.
Thumbnail courtesy of NOAA.