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Science Tropical Weather

Invest 92L (Pouch 14L) , Invest 93L (Pouch 15L)

It seems that that Cape Verde season has begun in the Eastern Atlantic.
Two Invests, 92L and 93L have been tagged and designated.
92L had been designated on 8/7 but the next day it was deactivated only to be activated again on 8/9. 93L on the other hand has just been activated late yesterday. This is the time of the year where most of the tropical waves come off the edge of Africa and possibly develop into tropical cyclones.

Invest 92L
Invest 92L is a no longer a well defined low pressure system. Instead it now is negatively tilted system that looks very ragged. Although there is dry air entrained into the system, 92L may become at least a tropical depression once the system begins to create a lot more convection within the center, assuming it survives. This may take a few days due to the SAL or dry air that is wrapping around the system from the NW and W of the center, thus inhibiting development. As 92L gets much further west the SST’s will be increasing allowing further development.

As for the track of 92L, this all depends on some of the timing, but a lot of the models are forecasting a trough that will be over the eastern seaboard which should allow a recurve once it lifts out and sending 92L out to sea. The problems with that is the long term and the models will change. 92L will probably recurve, but how close to the eastern seaboard is still early to predict.

Invest 93L
93L who came off the edge of Africa yesterday afternoon and is a large system but it is somewhat linear and not looking like a well developed system with excellent cyclonic turning. Gradual development of this system is forecast. Because Invest 92L cleared the “path” of the SAL, 93L will not have the problems of dry air entrainment, at least for the next several days.
As 93L tracks WNW, the long term track is uncertain. The long term forecast, assuming that 92L will lift out due to a trough, a more zonal flow will develop somewhat in the area of central to SE Canada. (A zonal flow is more west to east and somewhat straight, whereas a meridional flow has more north and south). This will leave a weakness in the eastern seaboard because of the high pressure ridge that has been over Texas for several weeks now and the high pressure ridge in the Atlantic. Once there is that weakness, the Atlantic ridge will want to “fill that area of weakness”and expand the ridge westward. Depending on how deep the ridge develops will be the steering current for 93L. This weakness may allow 93L to get very close to the eastern seaboard or even have landfall as 93L starts a recurve due to a trough that is forecasted by the long term models. As usual, there is plenty of time for things to change, but all interests should begin to monitor 93L.

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