Caribbean depression is a hurricane threat to Central America this weekend

The tropical disturbance sliding along the Colombian coast has now been designated Tropical Depression Thirteen. The system's circulation became well enough defined for the disturbance to get the upgrade. A defined circulation is an attribute a tropical system needs if it is going to strengthen in the future.

The depression's westward trajectory south of the ABC Islands – Aruba, Curaçao, and Bonaire – is very unusual. Only a handful of systems in the record book going back to 1851 took that track. The most recent one was Joan in 1988. It ended up becoming a Category 4 hurricane before it hit Nicaragua.

The Caribbean waters between Nicaragua and South America are very warm, and storms can rapidly strengthen when the atmospheric environment is conducive. We saw this in November 2020 when Hurricanes Eta and Iota hit the Nicaraguan coast back-to-back as Category 4 storms.

This year, the upper-level winds are forecast to be conducive enough for the system that will become Tropical Storm Julia to strengthen into a hurricane, but the environment is not expected to be pristine. If the forecast is correct, likely-Julia will be held to Category 1 or maybe 2 strength when it makes landfall in a couple of days.

After landfall, the danger becomes flash flooding and mudslides in the mountains of Nicaragua, Honduras, and the surrounding countries.

Likely-Julia is expected to die over the tall Central American mountains. A week from now, we'll watch in the extreme southern Gulf of Mexico in case a part of likely-Julia's remnants combines with a cold front to spin up a low-pressure system. A couple of long-range computer models indicated that's a possibility, but it's a long way off, and lots can happen.

Otherwise, nothing is cooking in the tropics.