The disturbance designated Invest 94L – an area of low pressure moving westward between Africa and the Caribbean – is in no hurry to organize, but over the coming days, a conducive environment is expected to promote development as it nears the Lesser Antilles by late week.
The big question remains how much organization occurs before it makes its closest approach to the islands by Friday into the weekend. The European model and its many ensemble members maintain 94L will stay weak and continue westward into the eastern Caribbean as either a low-grade tropical depression or undeveloped tropical wave.
On the other hand, the American GFS model and its ensembles suggest a stronger storm or potential hurricane that curves northward toward the open Atlantic before reaching the islands later this week.
The differences in model forecasts highlight the forecast factors that lie ahead for 94L. The European model shows a more amplified upper-level pattern, with a bigger jet stream dip over the eastern U.S. that in turn pumps up the high pressure steering north of 94L. This sends the disturbance farther west toward the islands but also into a zone of higher wind shear and a less conducive area for strengthening.
On the other hand, the weaker subtropical steering shown by the American GFS allows the system to move farther north into a region of lower wind shear that encourages more strengthening.
The upshot is that a stronger system is favored north of the islands, with a weaker system more likely if 94L takes a more westward trajectory into the eastern Caribbean. Regardless, given the forecast uncertainty, interests in the eastern Caribbean – including both the Windward and Leeward Islands – should closely follow 94L’s progress.
Given the transition to a more fall-like pattern over the eastern U.S. in the week ahead, 94L will not make it far enough west to pose a concern for Florida.
Tropical Atlantic quiet otherwise for the foreseeable future
Other than 94L, the Atlantic should stay mostly quiet into next week. The upper-level pattern and water temperatures will be most conducive in the western Caribbean and extreme southern Gulf next week, but for now, models are keeping storminess and potential tropical activity confined to the eastern Pacific.