SAN ANTONIO – The National Hurricane Center now forecasts a stronger tropical storm before landfall Tuesday, while San Antonio remains outside the primary impact area.

Tropical Depression Five is becoming better organized over the northern Gulf of Mexico, and forecasters now expect the system to strengthen more than previously anticipated before reaching the Upper Texas Coast.

As of the National Hurricane Center’s 4 p.m. CDT Monday advisory, Tropical Depression Five was centered about 185 miles southeast of Port Arthur, Texas. Maximum sustained winds remained near 35 mph, with the system moving west-northwest at about 6 mph.

But the more important development Monday afternoon was not its current strength. NHC now expects Tropical Depression Five to become a tropical storm Monday evening and strengthen to around 60 mph Tuesday afternoon, shortly before reaching the northwestern Gulf Coast. That is a significant increase from earlier forecasts that showed a weaker tropical storm approaching the coast.

A Small Storm With Time to Strengthen

Hurricane Hunter aircraft investigating the depression have found its low-level circulation has become better defined. Satellite and radar imagery also showed increasing organization, including a more prominent curved band of thunderstorms south of the center.

Conditions over the Gulf are expected to remain favorable enough for additional strengthening before landfall.

There’s an important wrinkle, however. This is a relatively small tropical system and it does have much room to work with. Small tropical cyclones can sometimes respond quickly to changes in their surrounding environment, allowing their intensity to rise—or fall—faster than with larger systems. That’s one reason the National Hurricane Center increased its intensity forecast Monday afternoon.

Some hurricane-specific forecast models indicate even greater strengthening could occur before landfall. NHC says that is not currently the most likely scenario, but say that the possibility cannot be completely ruled out. The window for strengthening is short. But it isn’t closed.

Tropical Storm Warning Expanded

A Tropical Storm Warning is now in effect from Port Bolivar, Texas, eastward to the Vermilion/Iberia Parish line in Louisiana. Tropical-storm conditions are expected to begin reaching portions of the warning area Tuesday morning. That means preparations along the Upper Texas and southwestern Louisiana coasts should be completed before conditions begin deteriorating.

The system is expected to move generally west-northwestward through Tuesday before turning more toward the west and moving inland across Southeast Texas Tuesday night.

Storm Surge Is Becoming Part of the Story

There was another significant change Monday afternoon. A Storm Surge Watch was issued from High Island, Texas, to the Cameron/Vermilion Parish line in Louisiana. If the peak surge occurs around high tide, NHC says water could reach approximately 2 to 4 feet above normally dry ground in portions of that area. Farther east, from the Cameron/Vermilion Parish line toward Morgan City, Louisiana, approximately 1 to 3 feet of inundation is possible.

The amount of coastal flooding at any particular location will depend on the storm’s exact track, wind direction and timing relative to the tidal cycle. Residents in vulnerable coastal locations should follow instructions from local emergency management officials.

Heavy Rain May Still Be the Biggest Threat

Whether Tropical Depression Five eventually reaches 45, 50 or 60 mph isn’t necessarily what will determine its greatest impact. Rainfall remains a major concern. The National Hurricane Center forecasts generally 3 to 6 inches of rain from the Upper Texas Coast into portions of east-central Texas, with isolated totals approaching 9 inches. That could produce flash flooding, particularly where tropical rainbands repeatedly move across the same locations. Urban areas and locations with poor drainage will be especially vulnerable to high rainfall rates.

The rainfall threat will also travel inland with the system after landfall. That means this won’t necessarily stop being a flooding concern once the center crosses the coastline Tuesday.

What About San Antonio?

Despite the increased intensity forecast, the message for San Antonio has changed very little. Tropical Depression Five is not currently expected to produce direct tropical-storm impacts in San Antonio. The primary wind, storm-surge and flooding threats remain well east of the city.

South-Central Texas will, however, begin feeling the influence of increasing Gulf moisture associated with the system. That could produce scattered showers and thunderstorms Tuesday, with the better opportunities generally favoring locations east of Interstate 35 and especially toward the Coastal Plains. Rain chances decrease farther west.

For San Antonio, this remains primarily a moisture and rain-chance story rather than a tropical-storm threat. That’s an important distinction even as the system strengthens.

Why the Forecast Changed

Tropical systems close to the Gulf Coast can create a difficult forecasting problem. There isn’t much time between development and landfall.

Tropical Depression Five demonstrates why forecasters continue watching these systems until they actually move inland.

Earlier Monday, the circulation remained broad and poorly defined. Hurricane Hunter observations indicated that a better-defined center had developed this afternoon. Thunderstorm organization was improving, and the National Hurricane Center responded by increasing the intensity forecast.

None of that means rapid intensification is inevitable. It means the atmosphere is allowing the system to organize while it still has warm Gulf water beneath it. How efficiently it takes advantage of those conditions during the next 18 to 24 hours will determine how strong it becomes before landfall.

What We’re Watching Tonight

Three things deserve especially close attention through Monday night:

Intensity: Does Tropical Depression Five strengthen at approximately the rate NHC expects, or does its small circulation allow more rapid changes?

Track: Even relatively small adjustments could shift the corridor experiencing the strongest winds, greatest surge and heaviest rainfall.

Rainbands: Where persistent tropical rainbands establish themselves may ultimately matter more for flooding than the precise location of the center.

The National Hurricane Center’s next intermediate advisory is scheduled for 7 p.m. CDT, followed by the next complete advisory at 10 p.m. CDT.

For the Upper Texas Coast, the message Monday evening is increasingly clear: The time for preparation is running short.

For San Antonio, the message is equally important: We’re watching a strengthening tropical system in the Gulf—but its primary impacts remain well east of us. That distinction will remain important as Tropical Depression Five approaches the coast Tuesday.

Coastal Texas and Louisiana warned of tropical storm, while another storm moves toward Hawaii

MIAMI (AP) — The National Hurricane Center issued a tropical storm warning on Monday for the Gulf of Mexico coast from the Galveston and Houston, Texas, area to the western parishes of Louisiana.

As of Monday evening, the storm was classified as a tropical depression, an early stage of a tropical cyclone with swirling winds and thunderstorms over warm ocean waters. Forecasters expect it will strengthen into a named storm by Monday night and make landfall in Texas on Tuesday.

Texas Gov. Greg Abbott said the biggest problem expected from the storm is flooding. Forecasters are anticipating 3-6 inches (7-15 centimeters) of rain in the greater Houston area, with some areas of the state’s upper coast getting up to 9 inches (22 centimeters). More than 4 inches (10 centimeters) per hour could fall and will likely cause flash flooding in low-lying and urban areas, according to the National Hurricane Center.

“This is our first big storm of the season, and I’ll tell you, Texas is prepared,” Orlando Alanis of the Texas Division of Emergency Management said during a news conference.

The tropical depression was centered Monday evening about 105 miles (170 kilometers) south of Morgan City, Louisiana, and 185 miles (300 kilometers) southeast of Port Arthur, Texas, with maximum sustained winds of 35 mph (55 kph).

Crews worked Monday to clear dry vegetation that could ignite from a lightning strike and cause fast-spreading fires, Abbott said.

Meanwhile, the remnants of Hurricane Dolly brought rain and thunderstorms to parts of Haiti and the Dominican Republic, the Turks & Caicos, and the Bahamas, the hurricane center said.

In the Pacific Ocean, Tropical Storm Lowell was about 740 miles (1,190 kilometers) southeast of Hilo, Hawaii, and moving west with maximum sustained winds of 65 mph (100 kph). Forecasters said Lowell could rapidly intensify by Monday night or Tuesday and reach the vicinity of the Hawaiian Islands later this week.

Elsewhere in the Pacific, Hurricane Karina strengthened Monday into a powerful Category 4 storm, but isn’t threatening land, forecasters said.

Karina has intensified quickly since becoming a hurricane Sunday, fueled by warm waters far from any shore. It was centered about 1,055 miles (1,700 kilometers) west-southwest of the southern tip of the Baja California peninsula of Mexico and moving west, with maximum sustained winds of 140 mph (220 kph), the center said.

There were no coastal watches or warnings in effect, but waves were expected to affect Mexico and likely Southern California. Additional strengthening was possible on Monday, followed by fluctuations in intensity, the Miami-based center said.