The 2018 eastern Pacific hurricane season has been off to a very active start and has approached record levels in terms of activity through early-June. There have been two named storms that have formed so far: Aletta and Bud. Aletta rapidly-intensified into a category four hurricane on June 7th. On the heels of Aletta was Bud, and five days later he also became a category 4 hurricane.
Let’s talk climatology first. On average, the first two named storms develop on June 10th and June 25th, respectively. This year, both of the first two named storms formed earlier than their respective average dates. Now that may be impressive, but we have some even more interesting statistics. The first hurricane in the eastern Pacific basin usually is designated on June 26th, but not this year. There have been two hurricanes already, over one month ahead of the average second hurricane date (July 14th). Aletta and Bud also became major hurricanes (category three-plus) in a rather short period of time since they first became tropical cyclones (less than 48 hours). The first two major hurricanes typically form on July 19th and August 19th, respectively. This means that the eastern Pacific hurricane season’s activity can be considered to be over two months ahead of schedule.
We mentioned how Hurricane Bud formed shortly after Aletta. Their formation actually breaks the record for the shortest time period between category four hurricanes forming in such close proximity to each other. The below chart from Sam Lillo illustrates the time and distance between eastern Pacific category four hurricanes.
Going back to 1949, here’s the time and distance between some of the spatiotemporally closest category-4 hurricane formations in the East Pacific.#Aletta and #Bud is one of the closest pairs on record. pic.twitter.com/RL8GQLdIJX
— Sam Lillo (@splillo) June 12, 2018
There’s only been one other occurrence in recorded history that has had a more active start of intense hurricanes in this basin. That was during the 2015 season, when Hurricanes Andres and Blanca, who both reached category four strength, formed on May 28th and May 31st, respectively.
This year’s hurricane season in the eastern Pacific Ocean has been unusually active to start, and signs show that the season as a whole will feature an above-normal number of storms. According to NOAA (National Oceanic and Atmospheric Administration), there is “an 80% chance of a near-normal or above-normal season. An above-normal season is most likely (45% chance), followed by a 35% chance of a near-normal season and a 20% chance of a below-normal season.”