We continue to monitor Invest 99-L, tracking west to west-northwest over the Tropical Atlantic, and Tropical Storm Ernesto in the North-Central Atlantic.
Invest 99-L: Overall, 99-L continues to be disorganized. Convective (shower/thunderstorm) activity has become less robust since yesterday. There also is still only weak vorticity associated with 99-L, and there are no signs of a surface circulation.
Some development of 99-L remains possible over the course of tomorrow and Saturday, as wind shear will remain favorable in the 5 – 15kts range. Dry air is also not an issue and will remain a non-issue, and sea surface temperatures (SST) are warm in the 27 – 28 degree (C) range. There is still no support for development of 99-L from the three reliable global models used for predicting tropical cyclone genesis — the ECMWF, GFS, and UKMET. The 00Z ECMWF ensembles (EPS) have also backed off on the prospect of at least a tropical depression developing from 99-L.
In their 2:00 PM EDT tropical weather outlook the National Hurricane Center (NHC) did bump up the chance of development from 10% to 20% within the next two days, and kept the five day development chance at 20%.
Conditions still look to become unfavorable by the second half of this weekend as 99-L moves into the Caribbean, and should result in whatever 99-L is by then dissipating. Nonetheless, we will continue to monitor 99-L over the coming days.
Subtropical Storm Ernesto: Subtropical Depression Five attained subtropical storm status yesterday, becoming the fifth named storm of the 2018 Atlantic Hurricane Season — Ernesto — and the 4th subtropical storm.
As of the 11:00 AM EDT advisory, Ernesto is currently positioned 585 miles east-southeast of Cape Race Newfoundland, heading Northeast with max sustained winds of 45 mph.
Ernesto has begun to encounter colder SST, and is expected to become post-tropical/extratropical tomorrow.
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