Tropics About to Wake Up As We Finish June?

Lead Forecaster Daniel Crawley

Let’s talk about the tropics…the month of June has been pretty quiet compared to what we have seen in recent years. Alex did form off the East Coast of the United States and that was all.

In terms of global oscillations, the Atlantic Basin has been in negative phases, the Madden-Julian Oscillation (MJO) was in 6 during Alex and has been in the null phase for a while. That has likely played a role in the quiet month overall. That could be changing though as we get to the end of the month as the MJO will exit the null phase, briefly enter Phase 2 and work into Phase 1. Much like the winter time, Phases 8, 1 and 2 are favorable phases of the MJO for North American tropical impact.

We do currently have an African Wave that has exited into the Atlantic Ocean and for late June this is an impressive wave. This is really something that’s more likely a month from now instead of now…

The National Hurricane Center has outlooked the open Atlantic for potential development over the next five days…

The European Ensembles are already quite aggressive with this feature and developing it next week. You can see the probabilities of a tropical system are quite high nearing the Islands.

Looking at the 500 mb weather pattern for next week, there is a sprawling ridge across a good part of the Atlantic Basin, once again a pattern more reminiscent of later in the hurricane season and not late June. This should allow any feature to move generally west into the Caribbean. Once we get outside the current 7-Day forecast range the upper levels of the atmosphere could become quite supportive for a tropical system strengthening. There is a massive anticyclone at 200mb by next weekend.

The European is quite bullish in the long range of a storm in the Caribbean, in fact some probabilities of a hurricane are showing up as far as 7-10 days out in the Western Carrib.

Summary:

1. Madden-Julian Oscillation becoming supportive of increased tropical activity in the Atlantic Basin over next 5 Days and Beyond…
2. Any tropical impacts would begin near the Lesser Antilles by the middle of next week.
3. Western Caribbean impacts would be 7-10 Days out…
4. Abnormally strong signal of a feature lies in the model ensembles…