Just as Americans care about swimming, archery, and badminton for exactly two weeks every four years, so too do predictable patterns shape tropical weather.
Easterly waves roll off the African coast several days apart; upper-level winds often switch from favorable to unfavorable and back every two or three months; even the Atlantic itself seems to warm and cool on a cycle spanning multiple decades.
This week, with Florida and the Southeast in the possible path of a tropical system for the first time in 2024, we’ll look at how those patterns are aligning to scaffold hurricane risks this year over the short, medium, and long terms.
The short-term risk from a storm that may become Debby
The immediate focus is on a sizeable tropical wave near the eastern Greater Antilles that may ultimately become the next named storm, Debby.
After a lonesome week of plowing westward through dry air and Saharan dust, the wave is finally beginning to generate respectable convection today within its broad area of cyclonic low-level winds.
Large waves are hard to kill, but they also are slow to organize. Realistically, it’ll take until early Saturday for deep convection to potentially sculpt this scruffy wave into a tropical depression, by which time it will be over Cuba or the western Bahamas.
Given current trends, there’s a fair chance that “something” forms over the weekend in the general vicinity of the Florida peninsula, though a wild card is how much the wave is disrupted by land interaction over the next few days.
If the circulation can consolidate on the northern side of its expansive region of rotation, that would favor less disruption and faster organization. Consolidating a little farther south means the developing center of circulation would contend with the mountains of Hispaniola and Cuba, delaying organization.
As of mid-day Wednesday, the most concentrated low-level spin seems to be headed for the islands, though that could change.
This matters because a depression or tropical storm that forms earlier over the Bahamas would likely connect with a dip in the jet stream over the eastern U.S., turn north, and remain east of Florida as it passes out to sea. If the wave stays disorganized, it should continue west-northwest into the eastern Gulf.
Models suggest the eastern U.S. trough ships out and upper-level high pressure redevelops over the Southeastern U.S. next week, so if the disturbance gets into the Gulf, weak steering currents mean it could meander for a while. With water temperatures in the eastern Gulf in the upper 80s and favorable outflow aloft, that would be something that we’d need to watch.
Storm tracker: Monitor tropical wave as it moves toward Florida
A ‘tricky’ forecast with two paths: A rainy Florida sideswipe or a festering Gulf tropical threat?
In scenario 1, a faster-to-develop but sloppy tropical low moves north just east of (or over) the Florida peninsula this weekend, possibly scraping the Carolinas as it turns northeast after that.
Whether this mess is named or numbered, impacts would be limited to elevated rain coverage across Florida and the coastal Southeast between Saturday and early next week. This outcome would be a shot over the bow, heralding an active season to come, but not a serious concern in and of itself.
In scenario 2, a land-disrupted wave doesn’t develop by Saturday, just boosts rain chances in South and Central Florida as it crosses into the Gulf by the end of the weekend.
The disturbance then festers over the eastern Gulf in a generally favorable environment through the middle of next week or more, though there’s no guarantee anything would actually develop. It’s less clear what the endgame of this situation is, though. The wave’s large size and mountain-related discombobulation probably means organization would be slow if it occurs, at least initially.
Overall, I wouldn’t be too concerned at this stage.
While guidance has shifted a bit in the direction of scenario 2, convection is also outperforming model expectations. The situation remains fluid until a more trackable center of circulation emerges.
All that can be said with confidence is that elevated rain chances are probable in the Florida peninsula this weekend. It’ll take a few more days to sort out what may become of this messy wave.
The Carolinas to the eastern Gulf Coast should continue to monitoring the situation in the meantime.
Medium and long-term forecast: A brief lull than a flip into high gear possible
In contrast to the short-term forecast agita of being in a NHC area of prospective interest, the next week or two in the tropics don’t look too alarming otherwise.
Airmasses one to four miles up over the tropical Atlantic look to remain much drier than normal through mid-month, putting the kibosh on the development prospects of most tropical waves. Slow organization of a disturbance or two in the western half of the Atlantic is possible, but it’ll likely continue to be an uphill battle in the medium term.
Unfortunately, conditions are likely to flip to favoring more tropical activity than normal in mid-August and afterward, including the peak weeks of hurricane season in late August and September.
While I’ll dig into WeatherTiger’s updated seasonal outlook once the current mishigas is off our desk, suffice to say we continue to project a most likely outcome for the hurricane season ahead of around twice of average hurricane activity.
Extremely warm waters across the tropical and eastern Atlantic, weaker than average wind shear and low-level Atlantic trade winds in July, and a recent shift toward the onset of La Niña in the Pacific all support this forecast.
In short, keep your emotions in check regarding the wave that’s out there now, because like a fencer, BMX racer, or modern pentathlete you’ll need to pace yourself to go the distance in 2024. Keep watching the skies.
Dr. Ryan Truchelut is chief meteorologist at WeatherTiger, a Tallahassee company providing forensic meteorology expert witness services, and agricultural and hurricane forecasting subscriptions. Visit weathertiger.com for more information.
This article originally appeared on Tallahassee Democrat: Hurricane forecast: How tropical wave could impact Florida, Southeast
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