Surprising tropical disturbance formed in Yucatan Channel on February
An unseasonably disturbance developed over the northwestern Caribbean Sea on early February. It has recently been classified as Invest 90L by the National Hurricane Center (NHC). In addition, this disturbance has a chance of becoming a rare February subtropical depression or storm. I’m quite surprised that this disturbance formed on February. This similar event had happened on February 1952, when a tropical storm formed from a disturbance on the western Caribbean Sea; and subsequently moved northeastward and struck southwestern Florida. The 1952 Groundhog Day tropical storm is currently the only Atlantic tropical cyclone to form on February. Invest 90L’s convective structure remains organized, from satellite imagery. Surface observations suggest that the disturbance has a closed surface circulation, which is located just near the western tip of Cuba. In addition, surface pressure of 90L is falling. The system is currently moving stationary.
Figure 1. Infrared satellite image of Invest 90L. Image courtesy: RAMMB imagery.
Forecast of 90L
The small disturbance is predicted to move northeast towards South Florida. It has an opportunity to develop into a subtropical cyclone before merging with a cold front. Conditions are currently marginal for development. SHIPS model shows the shear around 90L remains marginal. Sea surface temperatures in its region are roughly 26 °C, which is also marginal. However, dry air in the west and south of 90L is likely hindering further organization of it, as seen on water vapor loops. Computer models depict the disturbance will barely become a subtropical or tropical storm. The NHC gives 90L 30% chance of becoming a subtropical cyclone during the next 48 hours. For now, we will keep a close eye on the system during the next several days, in case of significant changes. Regardless of development, the disturbance will bring strong winds and heavy rains to Western Cuba and South Florida.