Tropical Forecast Suddenly More Active

Still three weeks from the peak of hurricane season (September 10), the tropical forecast has suddenly become more active. The latest seven-day outlook from the National Hurricane Center (NHC) shows four areas of concern. Two will not affect the Texas Gulf Coast. Eventually, the other two could get close.

Chances of Tropical Formation

According to the NHC 8 a.m. update:

The red area at the right currently has a 70% chance of tropical formation in the next seven days.
The orange area has a 40% chance. Environmental conditions are only marginally conducive for further development of this system, but a tropical depression could still form during the next couple of days while it moves west-northwestward at 10 to 15 mph across the central tropical Atlantic.
Neither of those systems poses a threat to Texas.
The yellow area in the middle approaching the Lesser Antilles has a 30% chance of formation.
The yellow area on the left will move toward the Gulf of Mexico by early next week. It also has a 30% chance of tropical formation.

The NHC updates its website several times a day during hurricane season. So bookmark it and check back often for the latest forecasts.

Local Impact Felt by Next Tuesday

Jeff Lindner, Harris County’s meteorologist, has been sending out updates all week long on the last system. Here’s what he had to say on Friday morning, 8/18/23. “A low chance of tropical cyclone formation remains possible over the western Gulf early to mid next week.”

“A tropical wave will reach the eastern Gulf of Mexico late this weekend. As high pressure over Texas lifts northward and centers over the Midwest early next week, this wave will continue westward and approach the Texas coast by Tuesday or Wednesday,” said Lindner.

Possibilities include a tropical wave, tropical depression, or weak tropical storm moving inland along the lower or middle Texas coast. Conditions appear to be generally favorable for some slow development, but dry air is lurking along the U.S. Gulf coast that could wrap into any developing system. Also any developing system could encounter wind shear over the western Gulf from the outflow of powerful Hurricane Hilary in the eastern Pacific Ocean.

Any Development Most Likely Near Coast

“With that said, the system will be moving over warm sea surface temperatures and systems, especially in the NW Gulf under the right conditions can tighten up just prior to landfall. This may be a situation where whatever is going to happen with any development occurs very near the coast,” said Lindner.

Most Moisture Near Coast and West of Houston

Lindner concludes, “Regardless of development, tropical moisture will surge into the Texas coast as early as late Monday, but more likely Tuesday or Wednesday. For now, the greatest moisture looks to remain along and south of the I-10 corridor with areas north of I-10 still under the influence of the high pressure ridge over the Midwest. There will likely be a strong gradient in rain chances from south to north over the area next week with the potential for some desperately needed rainfall across the coastal locations.”

Subsiding air from the high to the north will determine how far inland the moisture and rain/bands reach. This map from the National Weather Service (NWS) helps visualize what the situation will look like by Monday, August 21.

Flood Risk Less than 5%

The risk of excessive rainfall that could cause flash flooding is less than 5% according to the NWS.

It’s pretty sad when you start wishing for a tropical storm. But we sure could use something to break the drought and cool us off. Yesterday’s high of 105 was the highest temp recorded in Houston since 1909, according to ABC13. And it could get close to that again today.