Hurricane Simon was sitting about 80 miles west of Cabo Corrientes, Mexico, on the evening of Oct. 12, creeping west-northwest at just 3 mph with maximum sustained winds of 100 mph. That is the position and intensity in the National Hurricane Center’s Intermediate Advisory 22A, issued at 5 p.m. MST on Oct. 12 (0000 UTC on Oct. 13), and every figure below is tied to a named advisory because the numbers shift with each update.
A hurricane that barely advances is dangerous in a different way from one that races ashore. The wind matters, but the larger threat along this stretch of the Pacific coast is rain falling on the same steep terrain for days, and a landfall that the forecast places in Sinaloa rather than at the resort towns now under the closest watch.
A hurricane that has weakened but not moved
As of advisory 22A, Simon’s center was near 20.3 degrees north, 106.9 degrees west, about 205 miles south of Mazatlan, with sustained winds of 100 mph, a minimum central pressure of 969 millibars and a motion toward the west-northwest at 3 mph. Earlier, in advisory 20, issued at 0900 UTC on Oct. 12, the storm carried 100-knot winds, equal to 115 mph, gusts to 120 knots and a pressure of 958 millibars, moving northwest at 4 knots.
Between those two products Simon lost roughly 15 mph of wind and gained 11 millibars of pressure, which is the signature of a hurricane that is filling in. Forward speed barely changed, so the storm has had no chance to leave its own wake behind. Advisory 20 had already indicated the weakening, and the later advisory shows it continuing through the day on Oct. 12, with Simon still well offshore of Cabo Corrientes and still over very warm water that keeps it a hurricane.
A distant ridge, a coming trough and a stalled track
The forecasters on duty for the forecast discussion, Katz and Blake, wrote that Simon is drifting northwest under the influence of a distant mid-level ridge over the south-central United States. They expect it to stay slow near the Mexican coast for the next few days, said track uncertainty is higher than normal, and noted that some computer models leave it nearly stalled in light steering. Later, a trough approaching from the northwest is expected to turn the storm northeast and speed it up, though the timing of that turn is uncertain.
The same discussion tied the weakening to mountainous terrain and easterly wind shear, while noting that sea-surface temperatures of about 31 to 32 degrees Celsius later in the week could slow the decline. The forecast discussion put landfall at around 72 hours, followed by rapid weakening over the high terrain of the Mexican interior, which is why the official outlook shows a hurricane dwindling to a remnant low within a day or two of reaching the coast.
The rain that a slow storm leaves behind
Advisory 22A calls for 5 to 10 inches of rain across coastal west-central Mexico, with isolated totals near 15 inches over Sinaloa by Thursday, Oct. 15. The discussion warned of life-threatening flooding and mudslides, especially in steep terrain, and of large swells producing life-threatening surf and rip currents along the southwestern and west-central coasts.
Dwell time is the reason a slow hurricane is an outsized rain threat: a fast storm delivers its water in hours, while one crawling at 3 mph keeps feeding bands of rain onto the same hillsides. Advisory 22A also said a dangerous storm surge is possible along the immediate coast near Las Islas Marias, with large, destructive waves near shore.
The official track and the alerts in force
As of advisory 22A, a Hurricane Warning was in effect for Las Islas Marias and a Hurricane Watch for Cabo Corrientes to Bahia Tempehuaya, with no changes made in that update. The advisory said hurricane conditions were likely in Las Islas Marias from Monday night into Tuesday, and possible in the watch area on Wednesday, with tropical storm conditions possible there by Tuesday night.
The track below comes from advisory 20 and may already have been updated. It had Simon at 22.3 degrees north, 107.2 degrees west with 80-knot winds by 0600 UTC on Oct. 14, then inland near 23.4 degrees north, 106.6 degrees west at 70 knots by 0600 UTC on Oct. 15. That is a forecast, not an observation, and no landfall had occurred at the time of the advisories cited here. The same advisory carried Simon as a post-tropical, inland remnant by Oct. 16 and dissipated by Oct. 17.
Readers should treat the figures above as a snapshot. The hurricane center’s Eastern Pacific page lists the newest advisory, and the Saffir-Simpson hurricane wind scale explains what a 100-mph storm can do to structures. Meanwhile, the center’s tropical weather outlook, issued the morning of Oct. 12, gave a separate disturbance south of Guatemala an 80 percent chance of becoming a tropical depression within 48 hours, which is a different system from Simon.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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