CROSSOVERS

Tropical Storm Alex is one of the rare systems that was 1st a named system in the east Pacific, crossed over into the Atlantic basin, and became a named system there as well. So rare that there's only been 5 others on record that have done so.

It should be noted that these systems all degenerated to remnants/areas of disturbed weather while over land, before re-emerging into open water in another basin and regenerating into a tropical cyclone. When this happens where the system then regains tropical storm intensity, it gets a new name, which is whatever the next name on the list in that particular basin is. This used to be the case for all systems, including those that maintained a low level circulation, which is more rare, as well. In 2000, the WMO (World Meteorology Organization) changed the naming policy where if a storm's core holds together on it's journey from one basin to another, it would retain the same name. This last happened in 2016 when category 3 Hurricane Otto crossed Central America from the Caribbean to the Pacific, retaining the name Otto in the Pacific.

Pacific crossovers into the Atlantic are more rare than those going from the Atlantic to the Pacific, by an almost 1:5 ratio. Since 1900 there have only been 6 Pacific to Atlantic crossovers, while there's been 29 Atlantic to Pacific crossovers. This is mainly due to the fact that most storms in the northern hemisphere, particularly those in the deep tropics (nearer to the equator), travel from east to west.

On May 28th, tropical storm Agatha formed in the east Pacific in the Gulf of Tehuantepec, off the southern coast of the Mexican state of Oaxaca. Just a day later it became Hurricane Agatha that eventually struck Oaxaca as a cat 2 blow. The mountainous region quickly transformed Agatha's small, compact center of circulation into remnants as it crossed the Isthmus of Tehuantepec, the shortest distance across Mexico (about 125 miles). The system eventually re-emerged over water in the eastern Bay of Campeche in, of course, the Atlantic basin. The remnants combined with a complex low pressure area in the western Caribbean and merged together north of the Yucatan Peninsula. Faced with a ton of shear in the Gulf of Mexico, the system struggled to develop as it started making it's way towards Florida. Because of it's expected development to a depression or storm, and it's proximity to land, the NHC designated it Potential Tropical Cyclone #1 (PTC1), so that watches and warnings could be issued. PTC1 never got it's act together in the Gulf of Mexico, as shear pretty much blew it apart.

It wasn't until PTC1 crossed Florida, with the help of a trough allowing this system to form a more solid center, that it attained the necessary requirements to become Tropical Storm Alex, the 1st storm of the 2022 Atlantic season. So it took longer than expected, but the Agatha-Alex crossover officially becomes the just the 6th Pacific-to-Atlantic crossover on record. 

Though rare, it's only been 2 years since we had our last Pacific-to-Atlantic crossover system. In the record breaking season of 2020, Tropical Storm Amanda formed off the western coast of Nicaragua in the Pacific. Amanda lasted just 3 hours before making landfall in southeastern Guatemala. The system degenerated into a remnant low as it crossed the Yucatan peninsula from south to north, and reemerged in the Bay of Campeche where it regenerated into Tropical Storm Cristobal. Cristobal did a loop, making an initial landfall on the southwestern coast of the Yucatan, then made a beeline straight north across the Gulf making a 2nd landfall near Grand Isle, LA as a moderate tropical storm with 50 mph winds.

6 years earlier (2014), Tropical Storm Trudy formed south of Acapulco, making landfall just east of there, and it's remnants re-emerged in the Bay of Campeche where it became a tropical depression, heading due east and making landfall in the Yucatan. The system crossed the Yucatan, splashed down in the Caribbean and became Tropical Storm Hanna. Hanna did a loop coming back west and made landfall near the Honduras-Nicaragua border. A year prior (2013) Hurricane Barbara made landfall in the Mexican state of Chiapas, the easternmost landfalling Pacific hurricane ever. It then crossed into the Bay of Campeche and became Tropical Storm Andrea, striking the big bend of Florida.

In 1989, Hurricane Cosme formed south of Acapulco, made landfall just east of there, and it's remnants traveled nearly 800 miles overland to near Brownsville.

The system then entered the Gulf of Mexico just east of Brownsville and became Tropical Storm Allison. This Allison (not the one in 2001) made landfall with 50 mph winds near Freeport.

Speaking of 2001 Allison, that system formed from a tropical wave that crossed South America and the southwestern Caribbean and entered the Pacific where a low level circulation formed. That circulation moved inland into Mexico, dissipated, and it's remnants crossed into the Gulf of Mexico and regenerated, becoming a tropical storm also striking Freeport with 50 mph winds, and eventually parking over southeast Texas dumping 35+ inches of rain and flooding Houston like had never been see before. Until Harvey, that is. This is one of several crossover systems where the system didn't gain at least tropical storm strength in at least one basin.  

Cosme/'89 Allison was the first of the named storms to do the Pacific-to-Atlantic jump. For the one prior you'd have to go back 66 years to 1923, long before storms were given names. In 1923 there was a tropical storm that formed southwest of San Salvador, made landfall in Oaxaca, crossed into the Bay of Campeche, became a cat 1 hurricane, and made landfall in Cocodrie, LA. This is technically the 1st official Pacific-to-Atlantic crossover of what would have been named storms (at least tropical storm strength) in recorded history.

At least 3 other developed systems made the Pacific-to-Atlantic crossover, but all 3 were tropical depressions in the Pacific, crossing over to become stronger in the Atlantic. In 2010 a tropical depression formed in the Gulf of Tehuantepec (Pacific). This system made landfall as a depression, meaning it did not get a name. The system crossed the Isthmus into the Bay of Campeche, where it regenerated into Tropical Storm Hermine, which made landfall near Matamoros, near the Texas-Mexico border.

In 1949 a tropical depression formed in the Pacific just south of El Salvador, made landfall as a depression, crossed over and entered the Bay of Campeche, and eventually strengthened into a strong category 2, almost cat 3 hurricane. This system made landfall just east of Bay City, TX, with the eye eventually going right over Houston. This hurricane is one of just 3 on record, to ever make Texas landfall in the month of October.

Finally, in 1902 a tropical depression formed south of Chiapas and made landfall as a depression in Oaxaca, crossed over and became a cat 2 hurricane in the central Gulf of Mexico, before weakening and making landfall as a tropical storm near Pensacola, FL.

So that's the list of the Pacific-to-Atlantic crossovers. Again, Agatha-Alex is just the 6th on record, but of those 6, 4 have now happened just since 2013.