• Bryan Norcross

The pause in tropical development will continue this week

The tropical atmosphere continues to be inhospitable for systems to develop. The tropical Atlantic is loaded with Saharan dust, which dries out African disturbances preventing them from generating the tall thunderstorms they need to develop. Meanwhile the upper-level winds over the Gulf of Mexico and the Caribbean Sea are hostile to any system that would try to get going.



A robust disturbance is forecast to move off the coast of Africa later today. It’s following another area of disturbed weather that’s already over the ocean moving in the general direction of the Caribbean.


Neither system is expected to organize, though a slight tropical moisture surge related to one or both of these systems might affect the eastern Caribbean islands late in the week.


The long-range computer forecast models don’t show any development at least into next week, which is encouraging.



There’s a broad pulse that slowly moves around the earth over the tropics called the MJO that alternately supports and suppresses tropical development. This is why hurricanes tend to come in clumps in a season.


Currently the MJO is supportive of tropical development over the Atlantic, but the dusty air and hostile upper winds are fighting back and winning. So storms aren’t forming. The timing of all of this might be fortuitous. Once this supportive phase of the MJO moves on, normally a suppressed phase move in.


It’s impossible to forecast these things precisely, but the suppressed phase might take us into August when the other negative factors tend to dissipate. Tropical storms and hurricanes sometimes develop during the suppressed phase, but generally there are fewer, and they are not as strong.


But don’t count your chickens yet. Most of hurricane season is still to come, even if August starts out slow.