Tropical Update: August 5th, 2017

In case you missed our Facebook updates, we now have Invest 90L in the Caribbean in addition to Invest 99L in the far Eastern Atlantic.

Invest 99L

Satellite images this afternoon show that 99L is still moving west, has some disorganized convective activity, and is still embedded in a decent envelope of moisture. Further more, data from CIMSS still shows that 99L has a decent amount of vorticity or “spin,” but that it is elongated (this is important, as it indicates that 99L is not all that well organized at this time, and that any development will take some time).

Latest track guidance for 99L.

Chance of Development: Despite 99L’s current lack of organization, it still has a chance to gradually consolidate and develop into a tropical cyclone over the next two to five days.

Sea surface temperatures and upper-level winds remain conducive for development, and there is still little dry air in close proximity to or immediately ahead of 99L, with the southern extent of the Saharan Air Layer (SAL) well to the north 99L. These favorable environmental conditions are still expected to persist over at least the next two to three. However, by Monday or Tuesday, dry air will increase and upper-level winds will likely become less conducive for development.

In their 2pm EDT tropical weather outlook the National Hurricane Center gave Invest 99L a 30% chance of developing over the next two days, and a 50% chance of developing over the next five days.

Model Guidance: Of the three reliable models used for predicting tropical cyclone genesis — the GFS, UKMET, and ECMWF — only the GFS and UKMET are forecasting development of 99L in their latest runs.

Potential Track and Intensity: 99L is still expected to track generally west to west-northwest towards the Lesser Antilles over the next five days, potentially becoming a tropical depression or storm as it does so. However, it is still too early to speculate on the potential future intensity of 99L if it does develop.The same goes for the track beyond the next five days.

Invest 90L

Satellite images this afternoon show that 90L is moving west-northwest, and that it has a decent amount of deep convective activity. Data from CIMSS shows that 90L has some vorticity or “spin.”

GOES-16 satellite image of 90L.

Chance of Development: At this time, development of 90L over the next two to five days appears very possible.

Upper-level winds are conducive for development, and sea surface temperatures are between 84 – 86 degrees Fahrenheit in the Western Caribbean and 86 – 89 degrees Fahrenheit in parts of the Southwest Gulf of Mexico. There is also plenty of moisture available in both the West Caribbean and Southwest Gulf of Mexico to aid development.

In their 2pm EDT tropical weather outlook, the National Hurricane Center gave Invest 90L a 40% chance of developing over the next two days, and a 60% chance of developing over the next five days.

Model Guidance: Of the three reliable models used for predicting tropical cyclone genesis — the GFS, UKMET, and ECMWF — only the GFS and ECMWF are forecasting development of 90L in their latest runs.

Potential Track and Intensity: If 90L develops, it is to early to pin down where it will track and how strong it might become. At this time, 90L is expected to track on its current west-northwest trajectory, towards the Yucatan Peninsula and Southwest Gulf of Mexico over the next four to five days — potentially becoming a tropical depression or storm as it does so.

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Caleb Carmichael
Caleb Carmichael

Caleb is the owner of Gulf Coast Storm Center. He is currently an undergraduate student at Mississippi State University majoring in geoscience with a concentration in broadcast and operational meteorology. While not yet a meteorologist, Caleb has been providing weather updates, news, and analysis for the Gulf Coast since 2014.

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