Invest 99L Slowly Becoming More Organized
Placed Tuesday, July 31, 2012 5:55 am
by Rob Lightbown www.crownweather.com
Invest 99L, which is an area of low pressure, is located about 1200 miles or so to the west-southwest of the Cape Verde Islands this morning. The latest satellite loops indicate that this disturbance is gradually becoming more organized as deeper thunderstorm activity seems to be firing near the low pressure system. I do think that we will see 99L continue to slowly develop over the coming days and I do think that we will see it become a tropical depression on Wednesday and then strengthen into Tropical Storm Ernesto as early as late Thursday.
Looking at the forecast guidance this morning: The GFS model seems to have backed off some on how much this system will develop in the coming days. It does forecast 99L to become a low-end tropical storm before it tracks across the Leeward and Windward Islands on Friday, but then forecasts it to fall apart as the low-level center outruns the mid and upper level center due to strong trade winds in the Caribbean.
The latest European model forecasts that 99L will develop into a tropical storm before affecting the southern Leeward Islands, the Windward Islands and Barbados during the day Friday. After that, the European model forecasts that this system will fall apart due to the aforementioned strong trade winds in the Caribbean. It should be noted that the 10 day European model forecast, valid for August 9th forecasts some reorganization and development of this system once it reaches the southern Gulf of Mexico.
The Canadian model continues to be the most aggressive and forecasts 99L to become a hurricane before it affects the northern Leeward Islands by Friday and forecasts this system to approach the Bahamas by late this weekend. The longer range Canadian model forecasts this system to affect the east coast of Florida right around next Wednesday and next Thursday. At this point, the Canadian model is the odd-man out and will be disregarded for now, however, as we saw with Debby and the correct forecast by the GFS model (also the odd-man out at the time), you can never rule out any one model forecast.
At this point looking at all of the environmental factors and weighing in the latest forecast guidance and the most recent satellite imagery, I think that we will see development into a tropical depression during the day Wednesday and then intensify into a tropical storm by later Thursday afternoon or during the night Thursday night. I currently expect that this system will track very near the island of Barbados on Saturday morning as a tropical storm and then affect the southern Leeward Island and the Windward Islands during Saturday afternoon with tropical storm conditions, including strong winds with gusts to 50 mph, heavy rainfall and rough seas.
Beyond that, the future of this system becomes very murky as strong trade winds in the Caribbean may cause future Ernesto to fall apart very quickly and dissipate. So, at this point, we should concentrate on the fact that we do have a slowly organizing tropical disturbance that has a fairly good chance of becoming a tropical storm in the next few days.
I am monitoring Invest 99L closely and I will keep you all updated on the latest.
The next tropical weather discussion will be issued by 7 am EDT/6 am CDT Wednesday Morning.
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