It’s official: the Eastern Pacific hurricane season is upon us as today, May 15th is the official start of the 2012 season. Since the beginning of the 1970s the season has averaged fifteen named storms, eight hurricanes and three major hurricanes of Cat 3 or higher. The season starts two weeks earlier than normal this year because of warmer Pacific waters and weaker wind shears earlier in the season compared to the Atlantic.
The Atlantic hurricane season gets a lot of attention and press coverage in the U.S. However, the Pacific hurricane season which can whip up some powerful tropical storms and hurricanes is a major source of worry for those people living in the southwestern portion of the country. While it’s true that most of the tropical storms and hurricanes which occur during the Pacific hurricane season do not affect landmass and are mostly of concern to those in the shipping industry, the weather patterns at the start and end of the season are capable of producing tropical storms and hurricanes which can impact Mexico and the southwestern United States.
Arizona is the state in the U.S. that has seen the most storms during the Pacific hurricane season. The National Weather Services tells us that eight tropical storms have make their way into that state since the mid 1960s. Five of these storms were significant including Tropical Storm Nora in ’97 that caused widespread, significant flooding and which packed winds of over 50 miles per hour.
Flooding is the biggest threat to the southwest during the Pacific hurricane season. Even when a tropical storm has dissipated before reaching U.S. soil, it’s moisture can dump heavy, drenching rains on the coastline as it moves along on its course. Serious flash floods can and have occurred during this season which have resulted in some fatalities across central and southern Arizona. This is what happened with Tropical Storm Norma in 1970 as heavy flooding occurred – resulting in two dozen people losing their lives.
Right on schedule is the first tropical depression that has formed in the eastern Pacific, more than 600 miles off the coast of Mexico. The storm, named Aletta, took shape yesterday from a thunderstorm cluster in the Pacific. This storm is only packing winds of 40 miles per hour and is forecast to weaken before it breaks apart in the open ocean in a day or two. The development of Aletta is a sure sign that more storm activity in the Pacific is coming. The stirred-up appearance in the clouds in the eastern Pacific do suggest that there may be a new storm developing there over the next few days.