The system may become Tropical Storm Idalia
Forecasters are watching the Atlantic for further tropical storm development as Franklin strengthens
Even as Tropical Storm Franklin gains strength after hitting Hispaniola, meteorologists have their eyes on a new development threat in the Gulf of Mexico.
Accuweather, Accuweather
◀ Updated forecast for Sunday: IDALIA FORECAST: Florida faces high hurricane threat; Get ready now
A few weeks ago, a “time-traveling psychic” announced on a platform that I’m not online enough to be a part of, that Florida would be hit by a “Category 6” hurricane in September. Since social media views are inversely proportional to reality, this video has been viewed about 11 billion times.
Despite the invisible upvote of the great and powerful algorithm, the tropical threat facing Florida next week will not be a Category 6 hurricane, because such a thing does not exist. However, the state is increasingly likely to experience widespread rain, coastal flooding and wind impacts from the tropical system crossing the eastern Gulf of Mexico between Monday and Wednesday.
Here’s what we can say with some confidence today: First, the abusive disorder isn’t much to look at now, so nothing will happen right away. As of midday Friday, the area of interest was a widespread area of cyclonic transition in the northwestern Caribbean Sea, with scattered, disorganized thunderstorm activity. This circulation and convection will slowly merge near or over the Yucatan Peninsula and move slightly through Monday.
Tropics Update: Tropical Depression 10 forms in the Gulf of Mexico. Hurricane Idalia could hit Florida
Early next week, a strong dip in the jet stream extending from the Great Lakes far south will bring south-to-north directional streams into the Gulf. These guiding winds will pick up any lurking tropical system and push it toward Florida, with stormy weather starting Tuesday and the same storm crossing the Gulf Coast around Wednesday.
There is better agreement among leading weather models today than at the beginning of this week on this general scenario, and a named storm is more likely to develop in the Gulf by Tuesday than not. However, there is still a wide range of outcomes on the table regarding the potential strength of this storm and where its effects will be felt most acutely in Florida.
There are three main considerations that will tell the story, so let’s go through them one by one.
Key Consideration #1: Where will the position be formed and how will it be tracked?
The biggest source of uncertainty expected at this point relates to where a consolidated trading position forms over the weekend. Currently, the area of circulation and compact pockets of faster circulation extend over Central America, the Caribbean, and the southern Gulf. This is likely to intensify with the help of convection into one cycle by Sunday or Monday.
What we don’t know is whether this circulation will form over the Yucatán Peninsula, the northwestern Caribbean Sea, or the southernmost Gulf.
This is important, as models show that the ultimate path of the storm that might become Idalia depends on where it forms; Development to the north and east would shift the risk toward the Florida peninsula, and a turn to the west would favor a path toward the Panhandle.
In addition, because tropical cyclones derive their energy from warm ocean waters, circulation over the marshy lands of Yucatán would slow development until the circulation moves offshore. The time in water will matter a lot to how strong this thing is, so as little as possible is better. If the system is already a tropical depression over water by late Sunday, the odds of a hurricane are higher.
Key Consideration #2: The Role of Dry Air
While the models agree well on which steering currents will be present, there is a greater spread in how much mid-level dry air will influence the storm. Overall, the European model was more optimistic about the possibility of a stronger system, maintaining a dry air mass west of the developing core.
In contrast, the US GFS model was washing this dry air on top of a lot of turbulence as it moved across the Gulf of Mexico, creating an unbalanced mess of a storm – though the final round keeps it away from the center. Both outcomes are reasonable, and this also depends on where the trade actually takes shape. There is also the possibility of another wave of dry continental air reaching the storm midweek as it approaches Florida.
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Key Consideration #3: Gulf Water Temperatures
The unbridled heat in the Gulf is a major factor. Water temperatures range from 86 degrees to 90 degrees F all the way from the Yucatan Channel to Big Bend, which is two to five degrees warmer than normal. This heat deepens, providing tropical cyclones crossing the East Bay with a huge reservoir of potential energy to tap.
Extreme water temperatures alone cannot make a storm viable, but if other components such as low wind shear and mid-level humidity are present, they compress the timeline for intensification. The day and a half to two and a half days it will take this thing over near-90-degree water is plenty of time to jump from tropical depression to super-hurricane if the environmental stars align.
Don’t expect the models to do this right because fast boosting is not something they expect well.
An impact tornado is possible, so prepare now
While it’s too early to make a specific prediction for how this will play out next week, Florida is seeing some severe weather in the Tuesday through Thursday time frame.
Depending on where the center forms, how much dry air the storm draws in, and how much time it spends above water, the most likely outcomes range from a rainy, lopsided tropical storm to something more like Hurricane Hermine or even a little stronger.
This doesn’t look like Ian’s situation due to the lack of time above the water and the underlying dry air.
“Stay alert and prepare”: A tropical depression could develop in the Gulf of Mexico
One historical storm worth looking at as a rough guide is Hurricane Gordon in 2000, which also meandered near Yucatán and then sped northeast toward Florida’s Big Bend under a similar steering pattern. Gordon peaked as a Category 1 hurricane in the eastern Gulf, but dry air weakened it into a tropical storm upon landfall.
However, Gordon caused significant confusion and delays along Florida’s Gulf Coast, including 3 to 5 feet of water, up to 5 inches of rain, and power outages.
In conclusion, it would be a good idea to travel back in time to see how it will end, and then verify those predictions when you return home using psychic powers.
However, in the real world, Florida will have to live in uncertainty for a few more days as the chaotic process of tropical cyclone formation continues. An impactful hurricane is certainly a possibility, so use this time to identify and fill gaps in your disaster kit. I’ll be covering this storm from start to finish, so stay tuned and keep watching the skies.
Dr. Ryan Truchalot is the chief meteorologist at WeatherTiger, a Tallahassee startup that offers forensic meteorology, expert witness consulting services, and agriculture and hurricane forecasting subscriptions. Contact us at ryan@weathertiger.com, and visit Weathertiger.com for an enhanced, real-time version of our seasonal forecast.
