Tropical wave headed to the hurricane graveyard

A tropical wave off the coast of Africa called 94L has the low potential of becoming Tropical Storm Bonnie next week, but the hurricane graveyard stands in its way.

First, any potential development would not threaten Florida due to another blocking ridge expected to build over Florida by the end of June.

Second, even if it could get close to the States, the timeline would be around the July 4th holiday weekend with ample time to plan accordingly.

There is a spot in the Caribbean Sea where tropical systems fall apart nicknamed the hurricane graveyard. Tropical development over the eastern Caribbean is so rare that it happened only 10 times from 1851–2008.

As 94L tracks into the hurricane graveyard, it will be interesting to see whether it suffers the same fate as most nascent tropical cyclones that pass through the low latitudes of the eastern Caribbean Sea.

What causes the Hurricane Graveyard?

It has to do with an increase of east winds in the central Caribbean that leads to a domino effect of detrimental conditions for storms.

1. Faster surface winds draw down sinking upper air that weakens thunderstorms.
2. The vertical change in winds called shear disrupts circulation in tropical systems.
3. Sea surface temperatures drop from the breezy ocean surface conditions mixing up cooler water.

All these factors culminate as winds pick up in June and peak in July south of Hispaniola. Winds peak in those months because the northern part of South America heats up and the contrast with cooler Caribbean sea temperature intensifies a thermal gradient and thereby boosts the zonal jet stream of winds.

But the protection does not last all season and some of the strongest hurricanes have ripped across the area later in the season. Eventually, the jet maximum shifts eastward and weakens as the hurricane season progresses into the most active months of August and September. The timing coincides with increased tropical development toward the latter part of the hurricane season throughout the Caribbean basin.

The climatology does not favor 94L becoming much of a storm but the GFS forecast model gives the easterly wave a 17% chance of developing in the Caribbean Sea next week. We’ll see if it overcomes the statistical odds.