Live updates: Tropical Storm Watch issued for Texas as first storm of season threatens millions

While Potential Tropical Cyclone One is already packing 30 mph winds and could easily lash the immediate Gulf Coast with gusts over 40 mph on Wednesday, it doesn’t automatically get the name Arthur just by getting stronger.

The National Hurricane Center follows a strict set of meteorological rules before upgrading a disturbance into a named tropical storm.

To earn the name Arthur, it isn't just about wind speed—it's about structural organization.

Stages of tropical development

Right now, the system is a broad, elongated area of low pressure. For an official upgrade, Hurricane Hunter aircraft flying directly into the system early Wednesday must find a well-defined, closed center of circulation.

This means the winds must be spinning in a complete, uninterrupted counterclockwise circle around a definitive low-pressure core, with deep thunderstorms wrapped directly around that center.

If the reconnaissance flights find wind speeds matching the tropical storm threshold (40 mph or greater) but those winds are just blowing in a straight line or an open wave format without that closed loop, the NHC will keep it classified as a Potential Tropical Cyclone.

This serves as a vital reminder for coastal residents: a system doesn't need to be officially named "Arthur" to pose a severe hazard, as dangerous winds and catastrophic flooding will happen regardless of its structural title.

Now that the National Hurricane Center has officially designated the system as Potential Tropical Cyclone One, all eyes are on whether it can successfully organize into Tropical Storm Arthur before running out of time.

The broad area of low pressure is currently sitting inland over South Texas, but it is forecast to slide northeastward and emerge over the northwestern Gulf of America tonight.

Once it hits the water, a meteorological tug-of-war begins between atmospheric ingredients favoring and hindering its development.

FOX Weather exclusive tropical threat map showing where Potential Tropical Cyclone One is most likely to produce tropical storm conditions this week.

There are two major checkboxes working in the system's favor. First, sea-surface temperatures in the northwestern Gulf are sizzling in the mid-80s, providing plenty of raw thermal energy to fuel the storm.

Second, favorable large-scale lift aloft—provided by its close proximity to a sharp dip in the jet stream—is helping to exhaust air away from the center, encouraging thunderstorms to bloom.

However, the system faces two massive roadblocks.

It is running into moderate wind shear, which acts like an atmospheric blender, tearing at the storm's vertical structure and preventing it from stacking up efficiently.

Furthermore, its timeline is incredibly restricted. The system will only spend roughly 24 hours over the open ocean before steering currents drag it back inland over the upper Texas or southwestern Louisiana coast on Wednesday night.Because of these limiting factors, there is absolutely no indication that this system will become a hurricane.

Even in a worst-case scenario, we are looking at a mid-tier tropical storm.

Regardless of whether it officially earns the name Arthur, the main impacts remain unchanged: peak wind gusts over 40 mph will lash the immediate coast from Matagorda Bay to central Louisiana on Wednesday, alongside a life-threatening flash flooding disaster across the wider Gulf Coast.

When we talk about tropical storms and hurricanes, wind speed usually gets the most attention, but it is actually water that poses the greatest threat to life and property.

Storm surge is the abnormal rise of water generated by a storm, over and above the predicted astronomical tides.

Storm surge is the abnormal rise of water generated by a storm, over and above the predicted astronomical tides.

This dangerous phenomenon occurs when the powerful, swirling winds of a tropical system literally scoop up the ocean water and push it ahead of the storm's path, forcing a massive wall of water onto the shore.

Storm surge is uniquely dangerous for three major reasons:

• Immense power: A single cubic yard of water weighs nearly 1,700 pounds. When that weight is moving inland at high speeds, it easily demolishes buildings, sweeps away vehicles, and destroys coastal infrastructure.

• Rapid rises: Surge isn't like a slow-moving tide; it can cause water levels to rise by several feet in just a matter of minutes, trapping residents who delayed their evacuations.

• Battering waves: The surge acts as a elevated platform for large, destructive waves. These waves ride on top of the higher water level, acting like a battering ram against structures that would normally be safely out of reach of the surf.

What is storm surge?

As hurricanes churn over the ocean, the powerful winds actually push water to pile up on the coast. NOAA defines storm surge as the abnormal rise of water generated by a storm, over and above the predicted astronomical tide. The tide and storm surge together can reach up to 20 feet, according to the National Hurricane Center.

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Because storm surge can sweep miles inland through bays, rivers, and coastal inlets, you should never underestimate a 2-to-4-foot forecast.

It takes less than two feet of rushing water to sweep away most vehicles, making it vital to heed local evacuation orders long before the water begins to rise.

Along with the threat of torrential rain, Potential Tropical Cyclone One is bringing a dangerous coastal flood and storm surge threat to a wide stretch of the northwestern Gulf Coast. The National Hurricane Center warns that the combination of a storm surge and the natural tidal cycle will drive rising waters into normally dry areas near the shoreline.

Official storm surge forecast from the National Hurricane Center for the Gulf Coast

Water could reach 2-4 feet above ground from Port Bolivar, Texas to Morgan City, Louisiana if the peak surge hits at the exact time of high tide.

The deepest, most dangerous inundation will occur along the immediate coastline near and directly to the east of where the storm makes landfall late Wednesday night.

In these zones, the rising surge will be accompanied by large, destructive waves capable of causing significant beach erosion and flooding low-lying coastal roads.

Because surge-related flooding depends heavily on local geography and the exact timing of the tidal cycle, water levels can vary drastically over short distances.

People living in vulnerable waterfront communities from eastern Texas through southern Louisiana should monitor local National Weather Service updates closely and prepare for sudden, rapidly rising coastal waters over the next 24 to 36 hours.

A "Potential Tropical Cyclone" (PTC) is a special designation used by the National Hurricane Center to issue life-saving watches and warnings before a tropical system has officially formed.

Historically, forecasters had to wait until a storm developed a closed center of circulation and achieved tropical depression status before they could issue formal alerts, often costing coastal communities valuable preparation time.

Potential Tropical Cyclone is a term used by the National Hurricane Center before tropical storms or hurricanes form.

Under the PTC protocol, if a disorganized area of low pressure is not yet a tropical depression but poses a direct threat of bringing tropical-storm-force winds to land within 48 hours, the NHC can initiate full advisory packages.

This allows local officials to trigger early tropical storm watches or warnings, ensuring residents can secure their property and prepare for incoming hazards well before the storm wraps itself together.

The National Hurricane Center has announced it will officially initiate advisories on Potential Tropical Cyclone One at 11:00 a.m. ET (10:00 a.m. CDT) today as the system triggers widespread flash flooding risks over southern Texas.

This crucial designation allows forecasters to issue official tropical storm watches and warnings for the Gulf Coast ahead of the system fully organizing into a named storm.

Doppler radar showing tropical downpours approaching the Houston metro area this morning.

Heavy tropical rain bands are tracking inland off the Gulf this morning, heading directly toward the Houston metropolitan area.

The FOX Forecast Center is monitoring a thick shield of tropical downpours that is already bringing heavy rain to coastal communities like Galveston and is now pushing steadily north into the heart of the city.

Because these individual storm cells are loaded with deep tropical moisture and are moving relatively slowly, they are capable of dropping 1 to 2 inches of water in a very short amount of time.

While the primary tropical flood threat remains focused well east of the area along the Gulf Coast, emergency management officials in the Texas Hill Country are using this period of quiet weather to finalize critical public safety upgrades.

Following last year's devastating July 4th flash flooding along the Guadalupe River, Kerr County Emergency Management Coordinator Shorey Harmon announced that officials are actively establishing the strict Standard Operating Procedures (SOPs) that will govern the county's massive new outdoor siren network.

Built in partnership with the Upper Guadalupe River Authority (UGRA), the Guadalupe River Flood Warning System will feature high-powered, 50-foot siren poles capable of broadcasting both alerts and voice messages to vulnerable low-lying areas and youth camps.

To ensure there is no breakdown in communication during future severe weather events, the automated sirens will be linked directly to real-time river gauges and the UGRA’s "RiverHub" watershed dashboard, giving emergency managers immediate, data-backed authority to trigger the system the moment a National Weather Service Flash Flood Warning is declared.

Photos, videos reveal disastrous damage across Kerr County, Texas after deadly flash flood

As a deadly "flood wave" swept through Kerr County, Texas, on the Fourth of July, miles and miles of damage were left behind.

EXTREME WEATHER

While the primary threat from Invest 90L remains the relentless, multi-foot deluge of rain, residents across the Deep South need to keep an eye on the sky for a secondary hazard today: tornadoes.

The Storm Prediction Center has highlighted a zone from the Gulf Coast of Texas to Georgia for the threat of tornadoes today.

Tropical systems are notorious for creating highly sheared environments, meaning that wind speed and direction change rapidly with height in the atmosphere.

As the outer rainbands of Invest 90L rotate inland over parts of Texas and Louisiana and interact with a stalled front, localized wind shear can easily cause individual thunderstorms to spin, occasionally dropping brief, rain-wrapped tornadoes with very little warning.

Unlike the massive supercell tornadoes typical of the Plains in the spring, tropical tornadoes tend to form quickly and end fast, making it critical for residents under any severe weather watches today to have a reliable way to receive alerts even while focusing on the ongoing flood threat.

While the National Hurricane Center has raised development odds for Invest 90L to 60%, the clock is ticking loudly for this system to officially become Tropical Storm Arthur.

FOX Weather meteorologists emphasize that the disturbance has a very narrow geographical and temporal window to organize. Because the broad low-pressure center is currently hugging the Texas coastline, it needs to drift far enough offshore over the warm, 83°F waters of the open Gulf late Wednesday into Thursday to establish a tight, closed circulation.

Computer forecast models are in alignment over the future track of Invest 90L and its narrow window for tropical development over the Gulf of America this week.

However, atmospheric steering currents are expected to pull the system back inland over Louisiana relatively quickly.

This fast-moving trajectory back over land, combined with only marginally favorable upper-level winds, means Invest 90L only has about 24 to 36 hours to wrap itself together before it loses its warm ocean fuel source entirely.

While southeastern Texas bears the brunt of the initial tropical deluge today, the FOX Forecast Center warns that the core of the catastrophic flood threat will shift progressively eastward starting Wednesday.

As Invest 90L tracks along the upper Texas coast and pushes inland, the core of the steering currents will pull that massive, Pacific-fed moisture plume right along with it.

The Weather Prediction Center has highlighted where the threat of flash flooding will shift east over the next few days.

This environmental shift places Louisiana, Mississippi, and eventually coastal Alabama directly in the crosshairs for the latter half of the week.

Because atmospheric winds remain incredibly sluggish, these new areas face the exact same danger Texas is experiencing now: heavy tropical rain bands "training" over the same communities for hours on end.

Residents across the central Gulf Coast should prepare now for rapidly expanding Flood Watches, as several days of unrelenting downpours threaten to drop a widespread 5 to 10 inches of rain, triggering life-threatening flash and river flooding.

The Weather Prediction Center has highlighted multiple areas where the the threat for flash flooding is increasing this morning.

The FOX Forecast Center is working around the clock this morning, actively tracking multiple high-risk corridors along the Gulf Coast as an intense tropical deluge expands across state lines.

Our team of meteorologists is continuously monitoring real-time radar data, local gauge heights, and incoming National Weather Service alerts from eastern Texas, across southern Louisiana, and deep into coastal Mississippi.

Deep tropical moisture colliding with a stalled weather pattern means these dangerous, slow-moving downpours are hitting communities that are already dealing with completely saturated soils.

FOX Weather hurricane specialist Bryan Norcross joined Weather Command this morning to provide his expert analysis on Invest 90L as its development odds climbed to 60%.

When the Atlantic hurricane season kicks off in June, forecasters don’t typically look toward the coast of Africa where late-summer monsters are born. Instead, historical data from the National Hurricane Center shows that early-season development relies on warm waters closer to home.

Climatology maps highlight two primary hotspots for June tropical genesis: the Gulf of America and the western Caribbean Sea, with a secondary area extending just off the southeast coast of the United States into the warm Gulf Stream.

Historical maps show that most tropical storms form close to the U.S. and the Caribbean during the month of June.

Because the deep central Atlantic ocean takes much longer to heat up, early-season systems almost always spin up in these shallow, coastal basins where sea-surface temperatures can quickly reach the necessary 79°F threshold.

Because these storms form so close to land, they frequently bring a much shorter warning time for residents along the Gulf Coast and southeastern seaboard, often manifesting as slow-moving, heavy rainmakers exactly like the current system over the western Gulf.

The specialized crews of the Hurricane Hunters are prepping their aircraft today for their very first data-gathering mission of the Atlantic season into Invest 90L.

The National Hurricane Center has tasked the 53rd Weather Reconnaissance Squadron (Hurricane Hunters) with investigating Invest 90L in the Gulf of America early Wednesday morning.

The reconnaissance flight is scheduled to take off shortly before midnight ET tonight from Keesler Air Force Base in Biloxi, Mississippi, charting a course directly toward the western Gulf of America.

Crews expect to be inside the target area by 2:00 a.m. ET on Wednesday morning to investigate the broad area of low pressure.

By flying directly into the disturbance, the meteorological team will drop specialized sensors to measure exact wind speeds, central pressure, and search for a closed surface circulation.

The real-time data collected during this overnight flight will be fed directly into tropical computer models, giving forecasters critical insights into whether a defined tropical depression or Tropical Storm Arthur has officially formed.

The exclusive FOX Weather Threat Zone shows where life-threatening flash flooding is most likely through the workweek.

The FOX Forecast Center has highlighted a massive Threat Zone across the Deep South this week, mapping out exactly where the risk for life-threatening flash flooding is highest.

The high-risk corridor currently blankets a sweeping portion of the Gulf Coast—concentrated heavily along the Texas Gulf Coast through Louisiana—before stretching eastward across Mississippi and Alabama.

Because deep tropical moisture is slamming into a stalled front, thunderstorms are expected to repeatedly stall and dump immense amounts of water over these highlighted areas.

Residents inside this designated threat zone should expect rapid runoff, blinding downpours during their daily commutes, and a heightened risk for localized river flooding through the end of the week.

People are closely watching the northwestern Gulf to see if Invest 90L will officially organize into Tropical Storm Arthur, but the atmospheric reality on the ground is simple: the name ultimately does not matter.

While a tropical storm designation triggers headlines and flags wind thresholds, it is not a metric for rain potential.

The FOX Forecast Center says 5-8 inches of rain is expected across the South, with some places picking up more than 15 inches of rain this week.

The FOX Forecast Center warns that this system is drawing from a highly energized pool of deep tropical moisture—originating all the way from the Pacific—and it is tracking straight into a stalling weather pattern over the South.

Because the steering winds aloft are incredibly weak, these massive moisture bands are going to "train" or repeat over the same exact communities from Texas to Mississippi for days on end.

What’s the difference between a tropical depression, tropical storm and hurricane?

Every hurricane season, which officially runs from June 1 to Nov. 30 in the Atlantic Basin, a number of tropical depressions, tropical storms and hurricanes form. And there is a distinct difference between each type, like their surface and wind speed.

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Whether the National Hurricane Center clocks a 40 mph sustained wind speed to name the storm or leaves it as a disorganized depression, the primary hazard of this event has always been, and remains, a life-threatening, multi-foot deluge capable of widespread flash and river flooding.

As Invest 90L inches closer to the coast, the National Hurricane Center (NHC) has noted that Tropical Storm Watches or Warnings could be required later today.

To stay ahead of the alerts, it helps to understand the NHC’s strict, clockwork schedule.

The agency releases its full, primary advisory packages every six hours at 5:00 a.m., 11:00 a.m., 5:00 p.m., and 11:00 p.m. CT.

However, the moment that official coastal watches or warnings are actively placed into effect, the NHC steps up their schedule, rolling out intermediate public updates every three hours to provide continuous tracking information.

Coastal residents from Texas to Mississippi should closely monitor the late-morning and late-afternoon advisory times today, as these windows are the most likely targets for forecasters to initiate a "Potential Tropical Cyclone" designation and drop initial coastal alerts.

Texas Game Wardens and local first responders worked tirelessly from Sunday night into Monday morning, battling dangerous conditions to answer numerous swift-water and flooding rescue calls across multiple counties in central and east-central Texas.

During the chaotic night, game wardens successfully rescued five people whose vehicles had been swept entirely off the roadways by powerful currents.

Texas Game Wardens/Facebook

While emergency crews remain staged and ready to respond to ongoing calls for service, officials are issuing an urgent plea for the public to do their part to stay safe as the tropical deluge continues.

Drivers are reminded to monitor the forecast, obey all barricades, and never attempt to walk or drive through standing water, which can easily conceal washed-out roads and deadly debris.

If you encounter a flooded roadway, remember the life-saving rule: Turn around, don’t drown.

A soaking Tuesday morning is underway across the Deep South as a massive shield of tropical moisture unleashes heavy rain from eastern Texas all the way to Mississippi.

Doppler radar image showing where heavy rain is falling this morning from South Texas to Mississippi.

The National Weather Service has already issued a handful of Flash Flood Warnings for low-lying areas in Texas and Louisiana, where the initial rounds of rain are quickly pooling on saturated roads.

FOX Weather meteorologists warn that this is only the beginning; as daytime heating takes over and deep tropical downpours continue to regenerate over the same areas, the flash flood threat is expected to escalate rapidly through the afternoon, likely triggering widespread warnings across the entire coastal corridor.

A highly energized setup brought torrential downpours and early street flooding across parts of Southeast Texas on Monday as emergency officials finalized high-water rescue preparations.

For a complete look at how this dangerous system developed yesterday, check out our previous live blog coverage from Monday, June 15, which recaps the National Hurricane Center designating Invest 90L and the initial flash flooding reports.