A tropical wave nestled within a very large area of lower sea level pressure is tracking west through the Caribbean this weekend, and is in an area increasingly favorable environment for development. This feature has been tagged as Invest 99L, and NHC now gives it a 60% chance of becoming a tropical cyclone within 48 hours.

Invest 99L has an excellent blueprint for development, and this system has the potential to become a tropical cyclone that undergoes rapid intensification, which could take many by surprise heading into the new week.

In the lower levels, the circulation is already pretty well defined, with the blueprint for future spiral banding solidly in place. In the upper levels, winds are very light, and increasingly anticyclonic. Throughout the column, the air is moist, and relatively free of the dry air intrusions which have plagued so many other tropical features this season.

As of 3:00 AM Sunday October 21, 99L was centered near 15N 75W, with maximum sustained winds estimated at around 30 MPH.

This is where to put long range best guesses on intensity and forecast track. Long range model output discussions are also appropriate here.

At present, models are basically unanimous in developing Invest 99L within the next three days, but are very split with regard to its future track.