Hurricane Polo intensifies into rare category 5 storm off the coast of Mexico

Hurricane Polo has rapidly intensified off the coast of Mexico to become one of the most powerful storms of the season in the Pacific Ocean.

Key points

• NOAA's Miami-based National Hurricane Center called the storm "extremely dangerous" and remarked its intensification over 24 hours was "truly remarkable".
• Rainfall totals of up to 6in (15cm) are forecast, with 8in feasible in some areas.
• Sheinbaum highlighted the states of Jalisco, Colima and Michoacan as being at risk.
• Trade winds that typically blow from east to west throughout the Pacific Ocean can weaken or even reverse, allowing warm water to spread eastwards.
• The storm is predicted to skirt the coast of south-western Mexico, but is not projected to produce landfall, a warning from NOAA noted.

Meanwhile, a Hurricane Hunter aircraft, operated by the US National Oceanic and Atmospheric Administration (NOAA), flew into the storm on Tuesday and recorded sustained wind speeds near 180 mph (285 km/h), with stronger gusts.

In practice, the slow-moving storm is fuelling up on extremely warm waters caused by the El Niño climate phenomenon and is the season's third category 5 storm, the highest level on the Saffir-Simpson scale.

Meanwhile, the storm is predicted to skirt the coast of south-western Mexico, but is not projected to produce landfall, a warning from NOAA noted.

As it gradually drifts northwest, Polo will drive torrential rainfall in parts of Mexico's south-west coast – which could lead to deadly flooding and mudslides, NOAA stated.

Rainfall totals of up to 6in (15cm) are forecast, with 8in feasible in some areas. Residents have additionally been cautioned of sizeable ocean swells and life-threatening surf conditions for the next few days.

"So far, the information we have is that (Polo) will not make a direct landfall on the coast, " Mexico's President Claudia Sheinbaum remarked on Tuesday, but she cautioned residents along the Pacific coast to be vigilant. Sheinbaum highlighted the states of Jalisco, Colima and Michoacan as being at risk.

As of what NOAA called a "very conducive" environment of extremely warm ocean waters feeding the storm, data from the Hurricane Hunter aircraft indicated that Polo could still strengthen and would probable stay a category 5 storm for the next few days.

Scientists monitoring the ocean temperatures say the current El Niño climate phenomenon is now the strongest on record.

Daily sea surface temperatures in a key region of the central-eastern Pacific were 3.05C above average on 19 September – exceeding the previous record of 3.02C set during the particularly robust El Niño of 2015.

Some longer-term measures of El Niño have not yet hit record levels but this is projected to change, with the peak not anticipated until afterwards this year.

Warmer ocean waters mean storms can pick up more energy, leading to higher wind speeds.

El Niño is a naturally-occurring pattern. It happens regarding every two to seven years and tends to last for around a year.

Heat is then published from the ocean into the atmosphere which can boost global temperatures and drive changes in weather patterns worldwide.

Taken together, the developments around hurricane Polo intensifies into rare category 5 storm off the coast of point to a situation that is still moving, and the coming days should bring more clarity.