Outlook: 15 named storms ahead for Pacific hurricane season
Meteorologist, PhD
Wednesday, May 16, 2018, 2:18 PM - May 15th marks the beginning of the hurricane season in the east Pacific Ocean and all eyes are set on the west coast of Mexico and Hawaii, which are common destinations for many of the storms that form in the region.
(Related: Are you ready? Hurricane preparedness starts now)
Mexico's National Weather Service is predicting 15 named storms, 8 of which will become hurricanes with three of those exploding into major hurricanes; that is a a storm of category 3 or higher.
Last week we saw the first tropical depression (90E) forming far away from the west coast of Mexico. As the storm moved northwest, greater wind shear and overall unfavorable atmospheric conditions brought it to a stall and eventually it dissipated.
In 2017, with a lingering El Niño, the season turned out to be very active, with 20 storms developing, 18 of which developing into named storms. Nine reached hurricane status but only 4 made landfall in Mexico: Beatriz, Calvin, Lidia, and Max.
This year the timing of the transition between La Niña and El Niño will have a lot to say about the number and intensity of storms in the region. With La Niña gone and a weak El Niño developing we should expect a close to average season, which is reflected in the current forecast. If El Niño does form and intensify faster than anticipated, we could have a more active season, but that update will have to come later in the season.
La Niña, the cooling of the Pacific equatorial waters, tends to increase wind shear in the tropical east Pacific, which tears apart many of the storms that form and move northward. With El Niño, the warming phase of the equatorial Pacific, conditions are opposite, as wind shear relaxes and the clusters of thunderstorms that form around tropical cyclones tend to grow with ease and eventually develop into larger more powerful systems.
Actual sea surface temperature anomalies in mid-May 2018.
In an average year, we should see 15.4 named storms, with 7.6 becoming hurricanes, and 3.2 reaching major hurricane status.
