Window of development opportunity coming up?

It’s still early June and typically this time of the hurricane season means that things are usually quiet. Every once in a while we will get a June tropical storm or hurricane, but it’s not the norm. As most of you know, the season really begins to ramp up from about mid-August on. Usually….

This season might not be usual.

I am seeing the beginnings of signs that may point to a development window opening over the next week to ten days and beyond.

GFS and its ensemble members indicating a more favorable MJO state coming up for portions of the Western Hemisphere over the next couple of weeks

GFS and its ensemble members indicating a more favorable MJO state coming up for portions of the Western Hemisphere over the next couple of weeks

For starters, the Madden-Julian Oscillation or MJO is forecast by the GFS and Euro models to be moving in to the phase that often supports development somewhere within the Atlantic Basin. The MJO phenomenon is easy to think of as a period of fertility in the tropics, when deep convection can form and blossom, not just fizzle out and dissipate. While the MJO helps to enhance development it does not necessarily mean that development is a certainty.

The upcoming signal from the MJO is not especially strong but it is there (forecast to be there anyway) and could lead to better upper level winds over parts of the southeast Pacific and extending in to the western Caribbean and western Gulf. With water temps plenty warm in the region, all we need is a kick and it could lead to development in one basin or the other, maybe both. We will have to just wait and see.

If we look at the GFS operational model at the 850 millibar level which is about 5k feet up, we can see one week out from today that a wind shift or monsoonal trough begins to set up from the southeast Pacific, across Central America and in to the western Caribbean. This would act like a focusing mechanism for the air to come together or converge, probably leading to enhanced convection (thunderstorms) across the region.

GFS model at 168 hrs showing (yellow area) a wind shift and overall troff of low pressure stretched out over a large area, we call this a "monsson trough" and it can lead to development if conditions allow

GFS model at 168 hrs showing (yellow area) a wind shift and overall troughof low pressure stretched out over a large area, we call this a “monsoon trough” and it can lead to development if conditions allow

This large counter-clockwise “gyre” is so spread out that in and of itself it wouldn’t develop. We would need to see if an area of concentrated energy or vorticity breaks off and tries to develop out of this larger area of energy. If so, then a low pressure area could get going either in the Pacific or the western Caribbean – leading to the chance of a tropical depression or storm at some point.

As you can tell, the process is long and complex. I am not going to dwell on it day after day for two weeks but it is something to keep an eye on. At the very least, more rainfall than normal may be setting up for portions of Central America and it may lead to a named storm on one side of Central America or the other. Time will tell.

Then there is this interesting set up taking shape: The ECMWF (Euro) is indicating the possibility of an easterly wave (tropical wave) trying to develop way out in the deep tropics between Africa and the Lesser Antilles. Remember, water temps out this way are running above the long term average. If we do in fact see a strong area of energy emerge from Africa, it could take advantage of the warmer water and more favorable conditions overallĀ  and try to develop some. This would be highly unusual and a significant sign in my opinion that this season could be quite busy. Again, time will tell.

We live in an age when computer guidance and satellite information allows us to see in to the future of weather forecasting better than ever before. These early warning signs are helpful since we should no longer be totally caught off guard. It may not prevent a “Labor Day hurricane of 1935” scenario in which case we saw a TS become a Cat-5 hurricane in a very short amount of time but the advances in technology now allows us to be more aware than ever that a threat from the tropics is looming (or could be looming). My point is, do not be alarmed or worried. There’s no reason for that. Instead, be aware. We were told the season could be busier than average and these are possible signs of that happening. So just take note and pay attention a little more than normal perhaps. Applaud the fact that we have such tools at our disposal and as long as we know how to interpret them, it can be a good thing. After all, with such much at stake along our coastlines (all of us, not just the USA), the more lead-time the better; at least I think so anyway.

I’ll have more on Monday during my video discussion.

M. Sudduth 1:20 pm ET June 9


Complex weather pattern shaping up for the end of October as MJO arrives

GFS shows chance of heavy rain for portions of the Caribbean islands next week

GFS shows chance of heavy rain for portions of the Caribbean islands next week

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.