Bobby’s Sunday Meteorological Voice Volume 2, Episode 10 #njweather #BSMV
The Rarity of Seeing a Crossover Tropical Named System from the Pacific to Atlantic
Good Sunday Morning! I am Chief Meteorologist Bobby Klark of @Bobby’s Weather and Meteorologist apart of the NorCast.tv family here with my “almost getting back to” weekly blog about the good, bad, and ugly about our weather/media profession. But first…
Who would think the first weekend of June we would be seasonable and have low humidity… both days! That’s what we continue to have today, though fly in the ointment, the Shore will see cooler temperatures and battle the clouds, especially in the afternoon.
When tropical storm Agatha formed in the Pacific last week, it was the first time in 5 years that a storm was named before an Atlantic storm, though have to put an asterisk next to this since out of those 5 years, 4 were “sub-tropical” storms that the NHC decided we were going to name (Nor’Easters). It also became the strongest hurricane to make landfall in the month of May. Right there, you may scratch your head. Most tropical systems in both oceans, tend to move from east to west and yet for Agatha to make landfall, it moved west to east.
So how rare is it to see a system move west to east? Well, let’s start with the overall tropical season pattern. Most of us think of the hurricane season as systems moving off the African coast and heading west across the Atlantic, etc. Those more in depth with the season that follow the Pacific, most storms form somewhere off the Central American coast or south of the Baja and head west. However, with the season roughly starting mid-May through the end of November, that thinking shifts. Why? because the flow is different. From mid-May through roughly mid-June and from early October through the end of November, the flow is different. It trends more west to east. It’s also the time outside of when most tropical development occurs. Case in point, you may notice if you ever been on a cruise, most ports are always on the western side of the islands. this is for the fact most tropical systems move east to west. Of course, in the mid to late ’00s, that did little to help as we had several strong hurricanes late in October, specifically, that did major cruise port damage.
So why rename this system? It was Agatha. What is now Alex was still moisture and leftover circulation of Agatha. According the NHC, when a system loses total circulation (post-tropical or remnant low) it loses its features as that specific tropical system. So, as it crosses over to the other ocean, and reforms, it is like a brand-new system which gets renamed. Now, if it were to do this in the same ocean, it would get named the original name. So, if Agatha were still in the Pacific, fell apart, but reformed, it would be Agatha again.
Now the catch is what if Agatha never lost circulation heading over land? Well, then she would still be Agatha. The last time this happen is when Hurricane Otto (Cue: “Airplane!” Automatic Pilot) curtailed through Central America in 2016 and went on into the Caribbean, it kept its name. So as long as the system itself stays as a named tropical system, then it keeps its name going into each other’s ocean.
What Agatha to Alex did is a rare feat. The last time a storm completely fell apart in the Pacific and regenerated in the Atlantic was in 202 when Amanda in the Pacific became Cristobal in the Atlantic. Before that, since record keeping in 1851, only 4 storms have done it.
So, what we are seeing in Alex is one for the ages. It did dump nearly 15-20″ of rain over central and southern Florida as “Potential Tropical Cyclone #1” (That’s another debate for a later date), but overall will not go down as some major catastrophic event. Just some water cooler talk among meteorologists that we witnessed something rare in the field.
Thank you for joining me this week. Any comment, questions, or a topic you would me to tackle? You can comment below or email me firstname.lastname@example.org
Have a wonderful day everyone and I’ll see you next Sunday