Tropical weather analysis - May 25, 2010

Invest 90L

I have officially ceased monitoring 90L. It will still come close to the Carolinas within the next day or so, but will gradually weaken as it does so. Ultimately, it will be picked up by a large and powerful upper-level trough swinging southward from the north Atlantic. The system will also eventually be absorbed into this trough, losing its identity over the next several days. Impacts will be minor, though Bermuda may receive some tropical storm force winds, rough seas, and brief periods of heavy rainfall over the next couple of days as the system meanders in the general area.

Caribbean disturbance

The models have been less aggressive in recent runs over the possibility of a tropical disturbance in the western Caribbean. Vertical shear will still be quite low, however. Any culprit for a potential system in this area will come from Invest 90E, currently in the Eastern Pacific located over the Gulf of Tehauntepec. All of the models, save the CMC, unanimously bring this system to tropical storm status in about 48-72 hours, bringing the system across southeastern Mexico. In about four to five days, a weakness is forecast to develop in the Caribbean ridge, forcing the remnants of the system eastward into the western Caribbean. This is a very similar situation to Alma/Arthur in May of 2008.

Until I see some model consistency with this, however, I will not buy into it, though it's certainly possible, and definitely worth keeping an eye on. Vertical shear will be more than sufficient for organization of any system in this area, so it will need to be watched.

On one final note, the models have also recently been forecasting a gradual relaxation of the vertical shear across the Gulf of Mexico over the next week or so, as well as the eastern Atlantic Ocean. While I wouldn't expect any development in either of the aforementioned areas at the moment, it's certainly an indicator that La Nina is finally beginning to dominate. I suspect that we could see two to three storms in June, depending on the timing of the next upward MJO pulse.