Forecast Models Come Into Focus as Development Odds Tick Up for Next Week

A tropical system could form over the southern Gulf next week and threaten the northern Gulf Coast into next weekend

Saturday morning satellite showing storminess over the western Caribbean, the early stages of a system that could develop next week. Credit: Colorado State University/CIRA

Author’s note: This is a special Saturday edition of the tropical newsletter to discuss a tropical system that could develop and threaten the Gulf Coast later next week.

The early stages of a tropical system increasingly likely to form next week over the Gulf of Mexico will slowly congeal over the western Caribbean this weekend. Models have gradually come into focus with a growing threat to the northern Gulf Coast headed into next weekend, but important details – including future strength and areas at greatest risk – remain murky.

Odds of at least a tropical storm (39+ mph winds) moving within 150-200 miles of a given location from next Friday, September 27^th through next Saturday, September 28^th, according to the European forecast model ensemble system. Credit: Weathermodels.com

Interests from southern Louisiana to the west coast of Florida should follow the forecasts closely into next week.

Though we’ll continue to watch the trends here in South Florida, forecast models for now suggest any direct threat next week should stay to our west.

Slow organization into the first half of next week

As we’ve discussed in newsletters all week, the system will form within a broad area spin and storminess stretching from the eastern Pacific to the western Caribbean known as the Central American Gyre or CAG.

The CAG is firmly in place today across Central America, with a sharp dip in the upper-level jet stream helping to enhance storminess on its eastern side over the western Caribbean this morning.

This disorganized region of storminess is the formative stage of the system we’ll be following next week. The unsettled weather will persist and build this weekend into early next week as a more concentrated area of low pressure forms around the Yucatán Peninsula for the middle part of next week.

Growing threat to the northern Gulf by late next week

Overnight forecast models have come into focus, with our most reliable forecast models suggesting a growing threat to the northern Gulf Coast headed into next weekend.

Though the European forecast model and its ensembles continue to lean left with development over the central Gulf of Mexico and the GFS forecast model and its scenarios leaning right into the northeastern Gulf of Mexico, the distance between the two camps has shrunk considerably since yesterday.

Low pressure forecast from the European forecast model ensemble system (top pane) and American GFS forecast model ensemble system (bottom pane) for next Saturday, September 28^th. Both modeling systems show a strong low-pressure signal approaching the northern Gulf Coast. The European model favors a western track toward the central Gulf and the American GFS favors a course toward the northeastern Gulf. While the forecast is still 7 days out (translation: expect things to change), models generally agree on a growing threat to the northern Gulf headed into next weekend. Credit: TropicalTidbits.com

Forecast models have generally slowed the development and progression of the system for next week, now pushing possible impacts back into next weekend. This has increased the chances the system gets picked up by a jet stream dip digging into the southern U.S. late next week, which would bring any developing storm toward the northern Gulf.

The models are in good agreement right now with high pressure steering remaining over the southern half of Florida peninsula, which would essentially block any system from tracking directly into South Florida. Because tropical storms and hurricanes have a wide footprint, even periphery effects can be impactful, so we’ll continue to follow the forecasts, but at least for now forecast models suggest whatever comes of this stays to our west.

There’s still a chance the system doesn’t come together next week, stays broad and underdeveloped, and gets stuck in the southern Gulf or moves toward Mexico, but today that scenario is looking increasingly less likely.

I encourage everyone living along the north-central and northeastern Gulf, including along the west coast of Florida, to check back a little more frequently on the forecasts next week.

A few areas to watch over the open Atlantic but no threats to land

The National Hurricane Center is marking three areas over the open Atlantic for possible development.

The two areas over the central Atlantic – the easternmost system being the remnants of Tropical Storm Gordon – have a very narrow window for development this weekend but are headed out to sea and are no threat to land.

The newest area to watch between Africa and the Caribbean islands is associated with a tropical wave that’ll be pushing off Africa to start next week. Though models indicate some development possible with this disturbance deeper into next week, it’ll stay far away from land areas for now.