The next two weeks or so will likely be characterized by quite a bit of unsettled weather across a good deal of the Caribbean Sea and southwest Atlantic Ocean. The reason? The arrival of the wet phase of the MJO or Madden-Julian Oscillation and the resulting increase in convection across the Caribbean.
As I have been alluding to for some time now, the MJO was forecast to arrive in the western portions of the Atlantic Basin by mid to late October. Well, that seems to be happening now as we are beginning to see an increase in convection from the southeast Pacific to the Caribbean Sea. Over the next several days, a broad area of low pressure at the surface, also known as the monsoon trough, will set up across the southwest Caribbean, extending back to the west in to the east Pacific.
This pattern is very complex and often results in a lot of rain fall for the tropical areas. The result is usually a series of low pressure areas or depressions that form from this “grape vine” that is literally snaking its way across hundreds of miles of the tropics. As such, development is likely to be fairly slow but it is possible that we could have an east Pacific system followed by one in the Atlantic Basin, probably in the western or central Caribbean Sea.
My concern right now is for the heavy rain that seems almost a certainty of taking place. Reading the various NWS forecast discussions gives the notion that several days of heavy rain are possible for areas such as Hispaniola and possibly Cuba and as far east as Puerto Rico. Interests in the region should closely monitor the weather over the next five to ten days as this pattern begins to take shape.
It is also interesting to see how the various global models handle the upcoming pattern with regards to potential impacts to Florida. The GFS shows next to nothing really while the ECMWF forecasts a broad low pressure area to affect much of the peninsula with wind and rain by day ten. Obviously, this is quite far out in time and a lot can change between now and then. I think the bottom line here is that we are about to enter a two week period where a marked increase in convection and associated rain will take place for a wide swath of the Caribbean and southeast Pacific. Beyond that, we’ll just have to wait and see how the monsoon trough plays out and if any single low pressure center can take over and bundle all of the energy that is building across the region.
I’ll have regular updates each day here followed by the daily video blog posted to our iPhone app.