Tropical rainstorms could affect Texas and the Southeast this week

The stronger of the two, which the National Hurricane Center estimates has a 70 percent chance of development, is located in the southwest Gulf of Mexico. It will likely become a depression or tropical storm and make landfall in Mexico, but its greatest impacts could be in the United States: a moist flow on the north side of the circulation could dump excessive rain in Texas, with Double-digit totals possible in places, including Houston. The National Weather Service has already placed much of coastal Texas in a Level 3 of 4 risk zone for flash flooding and excessive precipitation.

Then there is a sneakier disturbance over the northwest Bahamas. This one could end up in a tropical depression or weak storm and sweep inland between northern Florida and the Carolinas by the end of the work week. Weather conditions with gusty winds and showers are possible, but exactly where they might land is still uncertain.

Hurricane season doesn’t peak in the Atlantic until mid-September on average, and experts are calling for a potentially hyperactive season this year. A combination of above-average water temperatures and an incipient La Niña – which will produce upper-altitude winds favorable for tropical development – ​​makes for a particularly busy season.

System 1 in the Gulf of Mexico

In satellite images, a large counterclockwise eddy is evident over the southwest Gulf of Mexico, the Caribbean, and the Yucatán Peninsula. This is a CAG, or Central American Gyre – essentially a large-scale low-pressure system with diffuse rotation. Scattered showers and thunderstorms surround its weak circulation.

It is possible that a more concentrated vortex lobe, or spin, will consolidate and move toward Mexico. This could lead to the formation of a short-lived tropical storm. If so, it would deserve the name Alberto.

What may have more impact, however, is the persistent moist flow that will wind northwestward into Texas. around the broader low pressure system. An incredibly moisture-rich air mass will rush into the Lone Star State Tuesday through Friday. This will bring heavy showers and thunderstorms with the potential for significant localized flooding.

Showers will reach the Texas coast Tuesday evening or Wednesday morning before dawn. Brownsville, Corpus Christi, Rockport and Houston-Galveston will all likely be affected. Showers will move north and west Wednesday and Thursday, likely dissipating Thursday and Friday as showers reach west toward the Permian Basin. In a given area, showers will likely last 18 to 24 hours.

Widespread totals of 4 to 7 inches are likely across South Texas, including coastal Texas near and south of Houston. It is unclear how much moisture is moving northeast toward the Golden Triangle. This area has been hit repeatedly by rains and storms since spring and is vulnerable to flooding.

It is also unclear how far north the precipitation will reach. The greatest chances for heavy rain are south of Interstate 20. A few locations in the Texas Hill Country or along the coast could see rainfall totals above 10 inches.

System 2 — Atlantic Ocean, Bahamas, Florida and Southeast

A large spin pocket exists over the northwest Bahamas. This pocket of rotation will continue to be deflected west-northwestward by a broader eastward anticyclonic force field over the central Atlantic.

Weather models have difficulty simulating where in this area a more focused rotation zone will develop. On Sunday, for example, weather models hinted at the possible formation of a tropical depression heading toward Florida; Monday morning, conversely, painted a picture of a system having more time to organize and making landfall Saturday in the Carolinas as a tropical storm.

It is therefore impossible to determine potential impacts or determine when hazards will occur. For now, the National Hurricane Center estimates a 30% chance of possible tropical development.