Tropical Storm Polo has formed off Mexico’s southwestern Pacific coast and is being closely monitored as forecasters warn it could strengthen quickly over the next few days.

The storm developed late Sunday and, according to the latest available data, had maximum sustained winds of around 40 mph (65 km/h) while located several hundred miles south of Manzanillo and southwest of Zihuatanejo.

Polo is moving slowly, but its forecast path and the atmospheric conditions surrounding the system have raised concern because the storm could intensify significantly during the first half of the week.

Polo could strengthen rapidly

One of the main concerns is the possibility of rapid intensification.

Forecast models indicate that Polo may become a hurricane and could potentially reach major hurricane strength by midweek if favorable conditions persist.

Rapid intensification can occur when a tropical cyclone moves over very warm ocean waters while encountering low wind shear and sufficient atmospheric moisture. Under those conditions, a storm can strengthen considerably in a relatively short period of time.

For that reason, Polo is expected to remain under close observation as its structure becomes better organized.

Heavy rain threat for southwestern Mexico

Even while remaining offshore, Polo could bring significant rainfall to parts of southwestern Mexico.

The states of Michoacán, Colima and Jalisco are among the areas that could see periods of heavy rain through the middle and latter part of the week.

In mountainous areas, prolonged or intense rainfall can quickly increase the risk of flash flooding, swollen rivers and landslides.

Coastal communities may also experience rough seas and increasingly dangerous surf as the storm strengthens.

Forecast track remains important

Polo is expected to change direction during the next few days.

The storm is forecast to initially move eastward before turning more sharply toward the north and northwest later in the week.

This expected turn will be closely monitored because relatively small changes in Polo’s track could significantly alter which parts of Mexico experience the heaviest rainfall, strongest winds and highest waves.

At this stage, there is still uncertainty over how close the center of the storm will come to the Mexican coast.

One of several active tropical systems

Polo is developing during an active period in the tropics.

Other tropical systems are also being monitored in both the eastern Pacific and Atlantic basins, making late September an increasingly busy period for tropical weather.

However, Polo is attracting particular attention because of its proximity to Mexico and the possibility that it could strengthen quickly.

What happens next

The next 24 to 48 hours will be critical for Polo.

Forecasters will be watching how quickly the storm organizes, whether a well-defined inner core develops and how closely it follows the projected track.

If rapid intensification occurs, Polo could become a much more powerful cyclone within a short period of time.

Residents and visitors along Mexico’s southwestern coast should continue to monitor official weather updates, especially in areas vulnerable to flooding, landslides and dangerous coastal conditions.