Hurricane Simon nears Mexico’s coast, where small track shifts matter

People along Mexico’s west-central coast face dangerous wind, flooding and waves even if Hurricane Simon’s eye stays offshore. The storm’s path also holds a less visible consequence: moving closer to the coast’s mountains could weaken it rapidly, while remaining farther out could preserve much more of its strength. That is the dilemma described in the National Hurricane Center’s Sunday forecast discussion.

In its noon CST advisory on Sunday, October 11, the NHC estimated Simon’s maximum sustained winds at 140 mph (220 km/h), making it a Category 4 hurricane. Its eye was about 65 miles (100 kilometers) south-southeast of Cabo Corrientes. The center was moving north-northwest, roughly parallel to the coast, and was expected to pass very near it that afternoon and night and remain close on Monday. Hurricane conditions were likely already occurring in the southern part of the warning area, the agency said, with those conditions spreading northward later Sunday into Monday. NHC advisory

The eye’s position marks the center of a much wider storm. Hurricane-force winds extended up to 25 miles from that center, and tropical-storm-force winds up to 80 miles. The NHC also forecast dangerous storm surge along the immediate coast near and east of where the center approaches land, accompanied by large, destructive waves. An eye at sea can therefore coexist with serious hazards onshore. NHC advisory

The noon hurricane warning covered the coast from Punta San Telmo to El Roblito, as well as Las Islas Marías. A hurricane warning means hurricane conditions are expected somewhere within the designated area; it does not predict identical conditions in every community.

Mexico’s national civil protection agency separately listed six municipalities in Colima and 22 in Jalisco under red alerts warning of very high danger. They included Manzanillo and Tecomán in Colima, and Puerto Vallarta and Cabo Corrientes in Jalisco. Those named communities give residents a more local reference than the eye’s position alone. Civil protection bulletin

The Sierra Madre mountains help explain why the forecast of Simon’s strength was unusually uncertain. In its morning discussion, the NHC said a path closer to shore or inland would likely allow the high terrain to disrupt the hurricane’s circulation—the organized flow of air around the storm—more severely, leading to rapid weakening. A path farther offshore could leave Simon substantially stronger than forecast. NHC discussion

A small eastward or westward shift thus affects two questions at once: where the center goes and how powerful the hurricane remains. The NHC had moved its predicted path farther west as some of its most reliable computer forecasts shifted that way. With unusually wide disagreement among the models, it expressed low confidence in predictions of both Simon’s path and its strength. Its forecast of weakening was a compromise between possible outcomes, with the pace depending partly on how closely the storm encounters the terrain. NHC discussion

The rainfall forecast contains another distinction that matters for understanding the danger. Through Monday, October 12, the NHC expected:

• 8–16 inches of additional rain across portions of southwestern Mexico.
• Isolated maximum totals of 30 inches for the whole storm across portions of Michoacán, Colima and Jalisco.

“Additional” describes rain still forecast to fall; a storm total covers the entire event. The two figures should not be added together, and the isolated maximum is not a prediction for every town. Neither is an observed rainfall accumulation. The agency warned of life-threatening flooding and mudslides, especially in steep terrain. Swells could also bring dangerous surf and rip currents over the next few days. NHC rainfall and coastal hazards forecast

In a Sunday notice, President Claudia Sheinbaum urged residents of coastal municipalities in Jalisco, Colima, Nayarit and Michoacán to remain sheltered until authorities announced that the danger had passed. She said precautionary evacuations toward safer areas were continuing, and asked people to follow civil protection recommendations and avoid public streets. Sheinbaum’s protection notice