Joe Lundberg

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Tropics Coming to Life

August 14, 2013; 9:37 AM ET

Wednesday, 11:30 a.m.

Outside of Tropical Storm Dorian, the past five weeks have been very quiet in the tropical Atlantic. That period of quietude may be coming to an end. There are two features that appear to be candidates for further organization in the next couple of days, one in the western Caribbean and another over the far eastern Atlantic. Here's a snapshot of the latest colorized water vapor image of the Atlantic:

In the case of the far eastern Atlantic wave, the dry air that has been so prevalent across the basin and deep into the low latitudes appears farther removed from the wave, and as such may have less of an impact on any potential development of the wave. If you recall in the case of Dorian, it was originally a very healthy and vigorous wave as it emerged off the African coastline, and initially it had little trouble in becoming better organized as it was properly shielded from all of the dry air. However, that only lasted for so long before it began to eat away at its circulation like a parasite, then any kind of upper-level shear all but ripped apart the low-level center.

The feature in the northwestern Caribbean is far more impressive looking. Here's the very latest enhanced IR image:

Several things come to mind at this point, all of which will have a bearing on what happens with this in the coming days. If you look at the various computer models, both tropical and non-tropical, you'll drive yourself nuts! Why do I say that? I say it because the solutions cover a multitude of options! Let me try my best to explain the various 'options' out there in an effort to try to hone in on a scenario, or at least a couple of scenarios, that would seem most plausible at this very moment given the fact we really don't have an organized low pressure in the northwest Caribbean.

1) System will move very slowly and is slow to develop in the next three days. Once clear of the Yucatan Peninsula and into the southern Gulf of Mexico, it will then develop, and if it stays far enough south to miss the upper-level trough ahead of it, it could make a run at Texas. This scenario is one played out by the 0z Aug. 14 Canadian model. Here's the 168-hour forecast valid next Tuesday evening:

The 12z NAM, for what it is worth, plays a similar card, only faster. Look at its latest 84-hour forecast for Saturday evening:

Of the two options offered up here in this slow development and, in particular, westward-tracking, trough-missing scenario, the NAM would seem more plausible simply by virtue of where this feature is already!

2) System will move more quickly and will be draw right up into the trough to its northwest. This would probably limit the development of any storm, as it would take the better part of the next two days to get the low-level center out from under sufficient to allow it become a system with tropical storm strength. Then, with the upper-level flow out of the south and south-southwest tugging on its cape, so to speak, it would both be draw right across the Gulf more or less south-to-north with some degree of speed, keeping it from getting too strong. If you look at the 0z Aug. 14 GFS model, it would lend support to that scenario:

That's the GFS for Saturday morning.

3) Development never really occurs, but the trough out ahead of it continually siphons moisture from the disturbance north across the Gulf and flings it at the central and eastern Gulf Coast and into the South and Southeast ink the coming days. This sort of idea has some support from the European model, and it would certainly lead to an extended period of excessive rains from the central and eastern Gulf Coast up into the Carolinas through the weekend.

I could present a number of other scenarios that would fit in between the broad ones I've outlined above, but suffice it to say most of the spray is integrated in these ideas. What will be critical to the eventual solution is how fast it actually does organize. With it already passing the tip of the coast of Honduras, and over open water, one would think it should get better organized fairly quickly in the next 24 to 48 hours. Should that be the case, the most logical solution would be for it to be pulled more toward the north and across the Gulf.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or


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Joe Lundberg
Joe Lundberg, a veteran forecaster and meteorologist, covers both short and long-term U.S. weather on this blog.