Tropical Storm Rachel is dumping up to 12 inches on four Mexican states on its way to major hurricane strength

Tropical Storm Rachel is spreading rain that the National Hurricane Center (NHC) expects to total 4 to 8 inches, with isolated maximums of 12 inches, across the coastal Mexican states of Guerrero, Michoacán, Colima and Jalisco. At 6 p.m. CST on Tuesday, September 29, the storm was 285 miles west-southwest of Lázaro Cárdenas with sustained winds of 70 mph, and forecasters expect it to reach hurricane strength that night and major hurricane strength by Thursday.

The center of Rachel is forecast to stay offshore. The rain and the surf are what will reach the coast.

Rainfall on steep ground in four states

The NHC’s Intermediate Advisory 11A puts the storm at 16.6 degrees north, 106.3 degrees west, moving northwest at 12 mph, with a minimum central pressure of 989 millibars. The agency warns that the rainfall could cause life-threatening flooding and mudslides in areas of steep terrain, which describes much of the coast between Acapulco and Puerto Vallarta, where mountains rise close to the shoreline.

Mexico’s own forecasts run in metric and are more granular. Citing the national weather service, the outlet Infobae reported that the Servicio Meteorológico Nacional classified the Michoacán coast as torrential, at 150 to 250 millimeters (roughly 6 to 10 inches), and the Guerrero coast as intense, at 75 to 150 millimeters, with Colima and the Jalisco coast in the very strong band of 50 to 75 millimeters.

Jalisco moved before the storm did, and the scale of its closures shows how seriously local officials read the forecast. State authorities suspended classes on Wednesday, September 30, in six regions of the state, and Governor Pablo Lemus Navarro urged residents to “avoid going out, remain alert to alerts and real-time updates,” according to El Informador. The University of Guadalajara suspended in-person activity at 31 campuses in the affected municipalities. The same report, citing Mexico’s national weather service, put Rachel about 485 kilometers southwest of Acapulco and south of Manzanillo, with sustained winds of 95 kilometers per hour and gusts to 120, and said officials anticipated it could strengthen into a Category 1 hurricane before affecting western Mexico’s central and southern Pacific coast.

Mexico’s Comisión Nacional del Agua, known as Conagua, is monitoring the system because of its proximity to the Michoacán, Colima and Jalisco coasts, according to the same report, and civil protection guidance urged people to stay out of flooded streets, riverbeds and unstable slopes. Coastal and mountain communities face the highest risk from river flooding, lightning, hail and strong gusts, and port authority closures are to be respected.

A forecast of rapid intensification

The rain outlook has grown with the storm. UPI reported earlier Tuesday a range of 3 to 6 inches, isolated 8, at 60 mph.

The NHC’s forecast discussion, written by forecaster Papin at 3 p.m. CST, put Rachel at 60 knots after aircraft reconnaissance found peak flight-level winds of 66 knots and dropsonde readings supporting about 60 knots at the surface. The discussion calls for “a period of rapid intensification from 24-48 h,” reaching 105 knots, roughly 120 mph, at the 48-hour mark before the storm reaches cooler water and weakens.

That number is what “major hurricane” means in practice. Under the Saffir-Simpson scale, hurricanes rated Category 3 and higher, with sustained winds of 111 mph or more, are called major hurricanes. The NHC’s own caveat on the scale applies here: it does not account for rainfall flooding, which is the hazard the advisory leads with for Rachel.

The warning line and the weather that follows

A tropical storm warning covers the coast of southwestern Mexico from Punta San Telmo to Playa Perula, and a tropical storm watch extends north from there to Cabo Corrientes. The advisory expected tropical storm conditions in the warning area within 12 to 24 hours and said the watch zone could see them overnight or on Wednesday. Rachel is following a track close to the one used the previous week by Hurricane Polo, UPI noted, which means the same stretch of coast is absorbing a second system in short order.

Dangerous surf and rip currents are forecast to spread along the coast and northward through the end of the week. The moisture will not stay in Mexico either. Fox Weather reported that moisture from Rachel is expected to feed a secondary wave of flooding across the Southern Plains and Midwest late in the week, after remnants of Polo helped set off flash flooding in the Southwest.

The figure to watch is the 105-knot peak, the NHC’s projection for two days out, made while Rachel was still a 70 mph tropical storm. Forecasters expect the storm to turn more westward after 48 hours at a slow forward speed, and the discussion attaches no landfall to it; how much of the rain reaches Guerrero, Michoacán, Colima and Jalisco depends on how close the outer bands pass to shore.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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