Tropical Cyclone Formation Likely over Gulf

According to the National Hurricane Center, a large area of disorganized showers and thunderstorms centered around the Yucatan has a 70% chance of turning into a tropical cyclone in the next two days. NHC gives it an 80% chance of formation within five days.

Environment Becoming Conducive for Development

Although upper-level winds are not currently conducive for tropical cyclone development. However, they should become more favorable during the next day or so. A tropical depression is likely to form on Sunday or Monday while the disturbance moves northwestward and then northward near the coast of northeastern Mexico. Further development will be possible through the middle of next week if it remains over water. However, because the storm has no organized center at this time, where it will make landfall is hard to predict.

“Global forecast models agree that a surface low will form, but where exactly remains in question,” says Jeff Lindner, Harris County Meteorologist.

The majority of the models predict the storm will focus on the western Gulf coastline. However, some models bring the storm closer to the Houston area.

Regardless, counter-clockwise rotation around any tropical cyclone should put Houston on the dirty side.

Heavy Rains Could Produce Flash and Urban Flooding

People along the western and northwestern Gulf coast should monitor the progress of this system. This disturbance should produce heavy rain across portions of Central America and the Yucatan Peninsula through today which may lead to flash flooding and mudslides.

According to Lindner, “By late this weekend, heavy rain will likely reach portions of the western Gulf coast. Expect rain over most of coastal Texas and Louisiana through the middle of next week. Localized significant rainfall amounts will be possible, potentially resulting in areas of flash and urban flooding.”

“Significant rainfall will be possible from Monday through Wednesday with excessive short-term rainfall rates of 2-4 inches per hour under any banding, training, or clustering of stronger cells.”

Jeff Lindner, Harris County Meteorologist

Expect very wet days early next week, especially near the coast. How far inland the heavy rains extend will depend on the degree of tropical cyclone development and the track of the storm. At this time, with high uncertainty, forecasters expect the heaviest rains near the coast with lower amounts inland.

Widespread rainfall amounts of 2-4 inches will be common over much of the area with much higher totals of 5-10 inches near the coast. Isolated totals in certain areas could exceed 10 inches.

While grounds are generally dry over the area, the magnitude of the rainfall in a short period of time could result in significant run-off generation especially over urban areas. Flooding concerns will increase as grounds become saturated early next week.

Winds/Seas/Tides

The high degree of uncertainty on where where any tropical cyclone will strike also affects winds, seas, and tides. But at the present, Lindner predicts easterly and southeasterly winds today into Sunday. He sees them increasing into the 20-30 mph range with seas building 6-10ft offshore by late Sunday into Monday.

Larger swells moving onto the coast will likely lead to some wave run-up and minor coastal flooding during high tides from late Sunday into early next week. 

Posted by Bob Rehak on 9/11/2021 based on information from NHC and HCFCD

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