Hurricane Polo Becomes Category 4 Storm in the Eastern Pacific as Heavy Rain Threatens Southwestern Mexico

Polo strengthens into a major hurricane

Hurricane Polo strengthened into a Category 4 storm in the eastern Pacific late Monday, becoming a powerful hurricane off the coast of Mexico.

The storm was forecast to bring heavy rain to southwestern Mexico while remaining offshore, according to the U.S. National Hurricane Center in Miami, FL.

Polo had maximum sustained winds of 130 mph, or 215 kph, late Monday. Forecasters said the hurricane could intensify further and reach Category 5 strength on Tuesday or Wednesday.

The storm is strong. It may become stronger.

Category 5 strength possible

On the Saffir-Simpson scale, Category 4 hurricanes have sustained winds of 130 to 156 mph, or 210 to 250 kph.

Category 5 hurricanes have winds exceeding 157 mph, or 250 kph.

Polo was already at the lower end of Category 4 intensity late Monday, and the forecast allowed for additional strengthening over the following one to two days.

Even if the center remains offshore, a hurricane of this strength can still produce dangerous rain, rough coastal conditions and hazardous surf along nearby coastal areas.

Storm expected to turn near the Mexican coast

As of late Monday, Polo was centered about 330 miles, or 530 kilometers, south-southeast of Manzanillo, Colima, Mexico.

The hurricane was moving east-southeast at 5 mph, or 7 kph. It was forecast to make a sharp turn toward the northwest and then west-northwest.

On that track, Polo would skirt the Mexican coast for several days without directly making landfall.

The center may stay over water. The rain risk still reaches land.

Tropical storm watch issued along part of the coast

A tropical storm watch was issued for part of Mexico’s Pacific coast, from south of Manzanillo, Colima, Mexico, to Tecpan de Galeana, Guerrero, Mexico.

A tropical storm watch means tropical storm conditions are possible in the area within two days.

The watch reflects the risk that Polo’s outer wind field and rain bands could affect coastal communities even if the hurricane center does not cross the shoreline.

Heavy rain threatens Guerrero and Michoacán

Heavy rain was forecast for coastal Guerrero, Mexico, and Michoacán, Mexico, through Thursday.

The main hazards from that rain are flooding and landslides, especially in coastal and mountainous terrain where water can run quickly down slopes and into low-lying communities.

Smaller rainfall amounts were possible in coastal portions of Oaxaca, Mexico, Colima, Mexico, and Jalisco, Mexico.

Rain bands can arrive in pulses. A coast may see breaks in the weather, then another round of heavy rain as the storm tracks offshore.

Why the offshore track still matters

The forecast keeps Polo from directly making landfall, but an offshore hurricane can still create serious impacts.

When a strong hurricane parallels the coast, its outer bands can push tropical moisture inland. That can lead to heavy downpours, rapidly rising streams and unstable slopes.

For southwestern Mexico, the greatest concern in the forecast is not a direct landfall. It is the combination of prolonged coastal rainfall and terrain that can quickly turn saturated.

Odalys also strengthening farther west

Farther west in the Pacific Ocean, Tropical Storm Odalys was far from land Monday.

Odalys had maximum sustained winds of 50 mph, or 85 kph, and was expected to become a hurricane by midweek.

The system remained over open water, but its expected strengthening added to the active pattern in the Pacific basin.

Fay weakens in the Atlantic

In the Atlantic Ocean, Tropical Storm Fay weakened to 40 mph, or 65 kph, southwest of the Azores, Portugal.

Fay was forecast to become a remnant low by late Tuesday.

No Atlantic hurricanes have formed so far this year, and the season has set a record for the longest start without a hurricane. The effects of this year’s El Nino have been suppressing storms before they can strengthen.