Early Start To The Season In The Deep Tropics

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Normally, threatening tropical waves for tropical cyclone development develop after August 1st. However, this year the deep tropics are looking active early! Tropical Disturbance 95L is approaching the Caribbean Sea and is encountering upper shear likely to prevent this system from organizing further.

Fig. 1: Morning satellite view of the North Atlantic basin.

Discussion: Normally, threatening tropical waves for tropical cyclone development develop after August 1st. However, this year the deep tropics are looking active early! Tropical Disturbance 95L is approaching the Caribbean Sea and is encountering upper shear likely to prevent this system from organizing further (Fig. 1). However, Tropical Disturbance 97L is following and currently located in the east-central tropics with a better chance of development drifting west-northwest the next several days. The system drifts into warmer water in 36-48 hours and with a low shear environment NOAA/NHC indicates a 70% chance of tropical storm development by Friday. Tropical cyclone models and the GFS take 97L west-northwest toward Cuba (as a tropical storm) in 5-6 days. The GFS turns this system into Florida mid-next week. ECM does not develop 97L. As always, forecast confidence is LOW until an organized system develops which could occur by tomorrow. The North Atlantic tropics/subtropics are mostly right at normal SST although the equatorial region is warming and the middle latitudes east of the Carolinas are very warm (Fig. 2).

Fig. 2: Current North Atlantic basin SSTA pattern.