I'm just a 23 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.
By: KoritheMan , 4:29 AM GMT on August 08, 2011
A tropical wave in the far eastern Atlantic midway between Africa and the Cape Verde Islands ("92L") poses no immediate threat for development. Despite afternoon estimates of a center along 11N, satellite animations and an earlier ASCAT pass indicate that the actual center might be closer to 8N. Assuming this is correct, the model consensus will have to shift south, perhaps significantly.
Figure 1. Statistical model consensus as of 2:00 PM EDT. Again, notice the time frame. These models are old, and we are anxiously awaiting newer ones.
Even supposing the center is at 11N, I don't see such a large poleward turn like these models are indicating. Yes, synoptic data does support a weakness in the Atlantic ridge along 35W in association with a trough digging southward. However, this trough is fairly zonal in nature, which will allow for the ridge to remain relatively persistent. On top of that, 92L is a very shallow system, with water vapor animations showing a large area of subsidence to the west, associated with the Saharan Air Layer (SAL). This should effectively curb any significant development until the system reaches 50W, when more atmospheric moisture could be available.
None of the models are very enthralled about development, likely out of reverence of this dry air. Also, if the center is closer to 11N, vertical shear profiles will be less favorable, as southwesterly upper flow associated with the aforementioned trough would likely encroach on the system from the west. On the other hand, if the center is farther south like synoptic data suggests, 92L could avoid the shear, although dry air would still be a large problem.
Having said all of that, I am not anticipating significant development of this wave over the next five days. However, as the wave gets closer to the Lesser Antilles, conditions may become more favorable. Assuming there is enough left of the wave by that time, it could try to sneak up on us in the Caribbean.
The tropical wave behind this system may pose a bigger threat.
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