Forecasting Ida In The Gulf


Tropical Depression 9 formed Thursday morning southwest of Jamaica and has strengthened into Tropical Storm Ida Thursday afternoon. On Friday afternoon, Ida became a hurricane.

Intensity Forecasting

This tropical storm will have some land interaction over the course of the next 36 hours, but despite this, conditions will remain favorable for strengthening into a hurricane over the weekend. Conditions once this storm passes Cuba and enters the Gulf of Mexico will be incredibly favorable for strengthening and development.

Water in the Central Gulf of Mexico is incredibly warm right now, and that warm water extends deep below the surface. In some locations, water is over 86°F more than 125 feet below the surface, meaning even as the storm churns deeper water to the surface, it’s still warm enough to support strengthening.

Upper-level winds would look to support development as well, with an upper-level high helping to “vent” Ida as it moves over the warmest, deepest water in the Gulf.

There remain possible limiting factors for Ida in this environment, although at this point, neither look overly likely. Ida could feel some northwesterly shear from Tropical Storm Nora as it approaches landfall, which could help to disrupt development some.

Latest model data suggests Nora’s shear would remain too far west of Ida to have significant impact, but a further westerly track by Ida, or a larger wind field than forecast for Nora could lead to some slight disruption in strengthening, although not enough to prevent Ida reaching hurricane status. Additionally, we have been watching some Saharan dust in the Atlantic basin.

At this point, it appears Ida will split the difference between a couple of batches of dusty air moving into the Gulf, but if the storm were able to ingest enough dry air, that could also slow, but not totally inhibit development.

Neither of these scenarios seem overly likely now, and there don’t appear to be any major inhibiting factors in the development of Ida once the storm enters the Central Gulf. Latest model intensity guidance suggests a hurricane at landfall, and perhaps a major (Cat. 3 or higher) hurricane.

Given the current forecast parameters we have, Ida has the potential to strengthen towards the high end of this guidance.

Forecast Track

Ida’s forecast track is northwest towards the Central Gulf Coast, with a north turn at landfall, which according to the National Hurricane Center forecast could be between Houston and Gulfport. Forecast models have honed in on Louisiana for landfall in recent runs, but there remains some uncertainty until the system develops further. Steering flow for the storm right now is out of the southeast, leading to northwest movement at around 15 mph. A strong upper-level ridge will help keep Ida from escaping east, but as Ida moves into the Gulf and strengthens, there remain some questions about how far west the system will move.

As the storm enters the Gulf, lower level steering is still out of the southeast, but upper-level steering winds are more southerly. That would mean that the stronger Ida becomes, the more likely it is to track further to the east. While we don’t anticipate direct landfall along the Alabama Gulf Coast, landfall in South-Central or Southeast Louisiana or even Southwest Mississippi would be possible if Ida became particularly strong in the Gulf, with a weaker Ida more likely to make landfall in Southwest Louisiana or Southeast Texas. The forecast models have been trending stronger and more eastward with Ida in previous runs, but uncertainty in exact track will remain until the storm becomes better organized.

Local Impacts

We will likely see impacts from the remnants of Ida here in North Alabama next week. Outer bands could move through Monday and Tuesday, and it’s possible that the remnant low of Ida could move directly over us. There’s still a good bit of uncertainty regarding the exact impacts Ida’s remnants could have here, but outer bands on the eastern side of tropical systems can produce heavy rain and tornadoes, and depending on the exact track of Ida, gusty pressure gradient winds would also be possible early next week. The greatest impacts from Ida in the Tennessee Valley would likely be felt Monday evening into Wednesday.

This can change quite a bit as we fine-tune the forecast for Ida in the coming days. be sure to check back for forecast updates over the weekend.

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