By: Civicane49 , 2:33 AM GMT on May 25, 2013
There are two tropical disturbances in the eastern Pacific today. One is Invest 91E located several hundred miles south of the Pacific coast of Mexico. The other one is the low pressure system located roughly 150 miles southwest of the coast of Costa Rica. This should be tagged as “Invest 92E” soon. Both of these systems are producing disorganized showers and thunderstorms on the latest satellite imagery. While two systems remain poorly-organized, I believe that the Costa Rica disturbance will stand a better chance of becoming the second tropical storm of the season.
Forecast for the Pacific disturbances
91E is not expected to organize significantly as it would continue to interact with the monsoon trough. I give this system a 10% chance of becoming a tropical cyclone in the next 48 hours. The system should move slowly in weak steering currents. The Costa Rica disturbance should continue to organize gradually in the next several days as it is expected to remain in favorable environmental conditions. It should become a tropical cyclone by Tuesday or so, and I give this disturbance a 20% chance of developing into a tropical cyclone in the next 48 hours. The system is predicted to move westward and then move west-northwestward as it will be steered along the southern periphery of the high pressure ridge over the Gulf of Mexico. The system would then move northward to the Mexican coast as the trough will amplify over the western United States by four or five days. The disturbance would bring a threat for heavy rains and strong winds for parts of the Mexican coast by next week.
Figure 1. Evening infrared satellite image of Invest 91E and the tropical disturbance near Costa Rica. Image credit: Mauna Kea Weather Center (MKWC).
Possible development in the western Caribbean on early June
The GFS as well as its ensembles are continuing to show a large area of low pressure developing over the northwestern Caribbean in few days after hurricane season starts in the Atlantic, which is June 1. The upward Madden Julian Oscillation (MJO) pulse is currently in the eastern Pacific and should move into the western Atlantic soon and would remain in that area until early June. The upward MJO pulse will help enhance convection across much of the western Atlantic. In addition, shear is forecast to decrease gradually across the Caribbean by early June, allowing development to occur. The models are depicting this system to move northward and affect the western Caribbean islands and the southeastern United States, especially Florida. Although high uncertainty remains for tropical cyclone formation, development is still not out of the question yet.
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