Tropical Storm Frank and Tropical Storm Georgette have formed well off the coast of SW Mexico. Frank will likely intensify into a hurricane for Friday and the weekend, then back to a Tropical Storm as it moves northwest. Georgette will move southwest for a couple days, then turn to the north. These storms are no threat to land and few ships are active in that part of the Eastern Pacific Ocean.
There have been six named storms so far in the Eastern Pacific, two of note. Hurricane Agatha moved northeast into Mexico on May 30, becoming the strongest May hurricane to hit land during the month of May. Heavy rain brought by the storm triggered flash flooding and landslides in many parts of Oaxaca. Agatha killed nine people, all in the Sierra Madre del Sur, with six others buried in landslides remain missing.
Tropical Storm Bonnie moved across Central America from the Atlantic into the Eastern Pacific, crossing Nicaragua, and becoming the first tropical storm to survive the crossover from the Atlantic to the Pacific since Hurricane Otto in 2016.
Bonnie retained its name as it moved from the Atlantic to the Pacific, so this year we had two tropical systems whose names began with the letter “B”.
Other tropical systems included Hurricane Blas, Tropical Storm Celia, Hurricane Darby (pictured above) which weakened to a minimal tropical depression that passed harmlessly south of Hawaii and Hurricane Estelle.
The majority of tropical storms that form in the Eastern Pacific off the coast of Mexico and move WNW miss land areas. Occasionally, they turn toward the Baja Peninsula and they can kick up the waves a bit in Hawaii, but many Eastern Pacific hurricanes and tropical storms stay well offshore and their effects are minimal.
The table above shows the ACE Index values through July 25 evening (Mon.). The ACE Index is a measure of the number of and the strength of tropical storms and hurricanes. The ACE Index numbers are given for each each ocean sector with the average ACE to date in ( ).
With the notable exception of the Northeast Pacific – all sectors have a below average ACE Index so far this year. The Northwest Pacific gets the most tropical storms and hurricanes (called “typhoons” in that sector) and their total ACE of 22.4 is only 33.6% of average ACE to date. In the Atlantic/Caribbean/Gulf of Mexico sector, the ACE to date is 2.8, compared to an average to date of 9.0.
There have been no tropical storms or hurricanes in the Southern Hemisphere. Globally, there are significantly more tropical storms and hurricanes in the Northern Hemisphere than in the Southern Hemisphere.
Here’s the current sea surface temperature anomaly (difference from average). Blue areas indicate areas where the surface sea temperature is colder than average and yellow/orange/red areas are warmer than average. You can see the La Nina – colder than average water temperatures along the Equator in the Pacific Ocean, though the coldest water relative to average has shifted from the Eastern Pacific more toward the Central Pacific.
There is cool water off SE Alaska – it was cooler than average for my trip to Juneau. The water is a little warmer than average in the Gulf of Mexico and along the Atlantic Coast – which shows the potential for significant tropical storms in the main August-October hurricane season.
Since the current pattern hasn’t changed a great deal since last year, it’s interesting to note that both September and October were warmer than average in West Michigan last year.