The disturbance is on the cusp or becoming Bonnie in the Caribbean as the tropics start to calm down
Caribbean Tropical Disturbance #1 is looking like it finally might be organized enough to be designated Tropical Storm Bonnie. The winds have been strong enough on the northern side of the system for days. But up to now, Hurricane Hunters flying through the system have not been able to find the required west winds on the bottom of the circulation to meet the definition of a tropical storm.
Almost-Bonnie seems to be surrounded by pristine atmospheric conditions and is over very warm water, so it’s not obvious why it’s taken this long. It appeared that some dry air, perhaps originating over South America, was gumming up the works yesterday. That might still be slowing things down.
The nighttime satellite pictures look like a tropical storm, but it’s easy to be fooled in a just-developing system. Once the sun comes up over the system and we get the morning data from the Hurricane Hunters, we’ll know if a full circulation has formed.
The storm is not far from the southern Nicaraguan and northern Costa Rican coast. It will bring heavy rain and very gusty winds across Central America later today and tomorrow.
This part of Central America is quite narrow, so almost-Bonnie is expected to survive the trek over the mountains into the Pacific with its circulation intact. Assuming is gets a name while it’s still in the Caribbean, the storm will still be called Bonnie as opposed to getting a Pacific-storm name. This is unusual because relatively few storms cross that narrow part of Central America. They usually track farther north and get tangled up in the big mountains. It’s only happened once this century when Otto pulled it off in 2016.
Almost-Bonnie is forecast to track north just offshore of the Pacific coast of Mexico and intensify, so they’ll be watching the storm over the next few days.
Tropical Disturbance #2 is approaching the Caribbean islands. Its atmospheric environment is not conducive to development, so it is forecast to pass across the islands over the next few days bringing heavy rain and some gusty winds as it moves east to west.
The disturbance we were watching yesterday in the Gulf of Mexico has moved ashore bringing very heavy rain to the Houston metro area and southwestern Louisiana. Some localized flooding is possible.
Overall, the tropics are calming down. Once almost-Bonnie is in the Pacific, the only active system will be the disturbance pushing across the Caribbean, and development of that system is unlikely. We should be good well into next week.