Welcome to WeatherTiger’s hurricane hub, providing weekly video discussions of active storms and potential threats in the Tropical Atlantic each Wednesday afternoon between June 1 through October 31. Look for more frequent updates when storms threaten the continental United States, with a particular focus on Florida. A weekly written forecast column can also be found in full below the video player.
Full discussion column below.
Also, don’t forget to read our August update to our 2019 Hurricane Season outlook for free right now!
WeatherTiger Weekly Tropical Outlook for September 11, 2019, issued 5:30PM
The middle of the second week of September marks the halfway point of hurricane season. On average, this week is the single most tropically active frame of the entire year; last September 12th, four named storms were roaming the Atlantic contemporaneously, including formidable Florence.
Today, following Tropical Storm Gabrielle’s dissipation on Tuesday, there are no active storms. This season’s peak days are instead a tropical intermission and opportunity to all go to the lobby and get ourselves a treat. Hopefully, it’s one of those classy theaters that sells $8.50 single-serve wine cups, because the first half of the season has been a white-knuckle ride.
This brief respite from checking satellite loops more often than Wilford Brimley checks his blood sugar is unfortunately coming to an end, and there are worrisome trends for the continental U.S. in both the shorter and longer terms.
Two disturbances in the Atlantic at present are worth monitoring closely over the next week to ten days, as both have at least some chance of impacting the U.S. coast.
The first and more immediately threatening of these is a trough of low pressure over the eastern Bahamas, Invest 95L.
Wednesday afternoon visible satellite imagery reveals this disturbance getting slightly better organized, with a sharp low-level wind shift and expanding area of deep convection close to the area of strongest rotation. The disturbance is interacting with an upper-level low over Florida, which is keeping development trends in check with 15 to 20 knots of southerly wind shear.
Moderate shear is expected to continue for the next several days as the system moves generally west-northwest around the southern periphery of Southeast U.S. high pressure, on a path through the southern Bahamas and towards the east coast of Florida over the next 48-72 hours. This shear means Invest 95L will be slow to organize, despite traversing untapped warm waters to the south of Dorian’s path.
Nevertheless, odds are increasing that a tropical depression or tropical storm develops prior to reaching southern Florida early in the weekend, and my guess is one does. The precise track is immaterial here, as the main impacts on the Florida peninsula even if the system becomes Tropical Storm Humberto will be 2-5” or more of rainfall.
The steering environment and the structure of Invest 95L both closely resemble Tropical Storm Gordon, which developed over the Keys and crossed the Mississippi and Alabama Gulf Coasts with 70 mph winds early last September. Like Gordon, Invest 95L is expected to arc west-northwest to northwest across the eastern Gulf Sunday and Monday. Exactly how long the disturbance has over the Gulf depends on whether the surface circulation consolidates further north (less time) or south (more time) over the next few days.
At this stage, 95L is certainly worth watching for the Gulf Coast from central Louisiana to the Big Bend. Though model reflections of this system in the Gulf are mostly weak, that doesn’t preclude further strengthening if the disturbance winds up having sufficient time to organize. Models generally underestimated and handled Gordon poorly, and the environment may be a little more favorable in the northern Gulf than early guidance suggests. We’ll be watching this short-fused sleeper threat to the Florida peninsula and eastern Gulf closely. Stay tuned.
Invest 95L probably will not be the only tropical system developing in the next 5-7 days. A tropical wave in the far eastern Atlantic is likely to become better organized by early next week on approach to the Lesser Antilles and may well intensify further in the western Caribbean or southwestern Atlantic by the end of next week.
Overall, we are much too far out to discuss specific tracks or threats from this possible system. Models, even good ones, don’t handle potential hurricanes skillfully eight or ten days ahead of time. However, guidance is in solid agreement on strong, high-latitude ridging being centered over the U.S. East Coast in the middle of next week, something models can predict well.
Historically, this is a steering current regime associated with elevated hurricane risks to the Southeast or Gulf Coasts. Given the potential for a front to push east out of the Plains in roughly ten days, the fate of this system could wind up being yet another question of pattern change timing, and thus a thorny forecast. That is a long, long ways off, however.
In short, tropical halftime is winding up. Bon Jovi might summarize our predicament by saying, “Whoa, we’re halfway there; whoa-oh, livin’ on a prayer,” before ham-fistedly changing keys and repeating the same thing again and louder. I’ll just say that I hope you enjoyed intermission, Weather Fans, because the lobby lights are dimming and the second act of Hurricane Season 2019 is about to begin. Keep watching the skies.
Dr. Ryan Truchelut is co-founder and chief meteorologist at WeatherTiger, a Tallahassee-based start-up providing advanced weather and climate analytics, consulting, and forecasting solutions to enterprises large and small. Get in touch at ryan@weathertiger.com or follow along on Twitter (@wx_tiger) or Facebook.