Tracking the Tropics: Disturbance 97L Organizing - Possible South Florida Threat
By: cchsweatherman , 2:31 AM GMT on July 21, 2010
During the late morning and afternoon hours, a tropical disturbance designated as Invest 97L has been slowly organizing and appears destined to become the second named storm, Bonnie, later this week. According to the latest data from the NHC, the center of the invest is estimated to be at 19.8N and 68.5W which places just off and between the northern coasts of the Dominican Republic and Puerto Rico and currently has surface winds around 35 mph.
In viewing the latest shortwave satellite, convection in recent hours has begun developing and concentrating near the estimated center and a defined band continues to produce heavy rainfall across the Virgin Islands to the east. In addition, southerly shear continues to impede on the western side due to the presence of an upper level low to the north. Related to this upper level low, outflow has not become well established with the exception of the southern portion of the system where wind shear remains quite light. But most importantly, radar, satellite imagery, and surface observations currently do not support a CLOSED surface low in association with this system which is necessary for further organization and classification.
Going on in time, the system should continue moving to the west to west-northwest during the next few days as there will be little change to the current steering pattern over the next three to five days. Given this forecast, it seems like this could very well become a threat to South Florida by Friday and Saturday as most computer models this evening suggest. Now what remains uncertain is the future intensity for this system.
According to the latest GFS upper level forecast, the upper level low should continue moving south and west in tandem with the system while a weak upper level high forms near the system. This should provide some good conditions for some development to occur, but not rapid development. In addition, dry air continues to exist preceding the system and may have some minor effects limiting intensification. Overall, I expect this to become Tropical Storm Bonnie, but am still skeptical as to whether or not this would become a hurricane before a possible threat to South Florida.
Based upon my analysis, residents in the Bahamas and South Florida should keep an eye on this system as tropical storm conditions could be possible Thursday through Saturday in the region.
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.