Heavy rains slam Texas coast as PTC One forms

A slow-moving tropical disturbance just inland along South Texas has already dumped heavy rain in a flood-prone area, and the risk is rising again as Potential Tropical Cyclone One (Invest 90L) could move over Gulf waters and intensify later this week.

By Tuesday morning, the Texas Gulf coast was already soaked—before the storm even truly started.

Tropical Storm Watches were issued for portions of the Upper Texas and southwestern Louisiana coasts as a slow-moving tropical disturbance lingered just inland along the south Texas coast. The system’s path matters: it could move offshore and develop into a tropical storm before turning back over land later this week. But the rain has not waited.

“Heavy rains have already drenched this flood-prone area. ” the latest tropical update said. adding that additional totals could exceed 10 inches by late this week. Flooding is the central threat. and it can become life-threatening quickly—especially in areas already saturated by recent storms and downpours.

At 11 a.m. EDT Tuesday, the disturbance known as Invest 90L was officially designated Potential Tropical Cyclone One by the National Hurricane Center. The designation is used when a system is close enough to land to bring significant impacts even though it is not yet a tropical depression or tropical storm with a well-defined center of circulation.

The timing carries a clear consequence for residents: the Potential Tropical Cyclone label allows tropical storm watches and warnings to be issued now. rather than waiting for a stronger classification. And while the system’s eventual name may not matter as much as what it delivers. forecasters noted that it is possible it could bring a named-storm label—potentially “Arthur”—if it develops. even before the average first Atlantic named storm arrives by June 20 (based on 1991–2020).

Satellite imagery showed the disturbance’s center remained over land near South Texas early Tuesday. While that limits its chance of developing into a tropical system while it stays inland. forecasters said it could move over Gulf waters later Tuesday or Wednesday near the Texas coast. Warm water and supportive atmospheric conditions could then allow development, even if it proves brief.

Sea-surface temperatures near South Texas were cited at 83.5°F (29°C). The forecast track along the coast would also pull in abundant tropical moisture—bringing heavy rainfall and gusty winds to areas that are already waterlogged.

Forecast models are not fully aligned on the details. The GFS model depicts a brief closed circulation developing later Tuesday just southwest of Corpus Christi. with the deepest convection spreading along the southeast Texas coast and into southern Louisiana through Thursday morning. Rainfall projections in that scenario concentrate the highest totals across parts of southern Louisiana and southern Alabama. with isolated locations receiving more than nine inches of rain.

The European model, in contrast, suggests greater organization. It keeps convection impacting much of the Texas coast while holding a broad circulation near the central and southeastern Texas coastline through Wednesday afternoon. It also points to the most intense thunderstorms striking much of the Deep South later in the week. with rainfall totals potentially exceeding six inches across many areas from Southeast Texas through Louisiana. Mississippi. and Alabama—again on top of what has already fallen.

That added layer is not hypothetical. Flash flooding struck central Texas on Sunday night, June 14–15, closing Interstate 35 in both directions in Waco.

And the atmosphere is primed for more. One indicator cited was moisture in the air above Corpus Christi: a weather-balloon sounding measured precipitable water in an imaginary column at 2.74 inches (6.97 centimeters) on Monday night. The update said this was the ninth highest value measured in more than 50. 000 soundings collected in the Corpus Christi area over the past 73 years. and the highest on record there outside of the core summer window from late June through late September.

It is not only local conditions. The disturbance is drawing on an incoming stream of very rich atmospheric moisture flowing northward from Central America and the eastern tropical North Pacific. Sea surface temperatures in the latter region were described as at record seasonal highs—linked to a months-long marine heat wave off the Pacific coast of Mexico combined with equatorial warming from El Niño’s arrival.

The Gulf coast has lived through repeats of this kind of setup: slow-moving tropical systems and tropical moisture can overwhelm drainage systems and turn routine storms into disasters.

In August 2017. Hurricane Harvey—after crashing into southern Texas as a Category 4 powerhouse—weakened into a slow-moving tropical storm that lingered for days near the upper Texas coast. The storm dumped an estimated 24.5 trillion gallons of rain in Texas and Louisiana. The update said the storm total of 60.58 inches at Nederland. near the Texas-Louisiana border. was the largest on record for any tropical cyclone in the 48 contiguous U.S. states.

Even when storms never reached hurricane status, the consequences were still immense. In July 1979. Tropical Storm Claudette produced the heaviest 24-hour rainfall on record for the contiguous U.S.—42 inches—deluging Alvin. Texas. just southwest of Houston. Slow-moving Tropical Storm Allison in June 2001 flooded some 70. 000 homes in the Houston area. taking 50 lives and causing $8.5 billion in damage (USD 2001).

In September 2019, Tropical Storm Imelda peaked with sustained winds of only 45 mph before coming ashore and weakening across southeast Texas. Yet it dumped more than 40 inches of rain in some areas. triggering massive rescue efforts and producing about $5 billion in damage (USD 2019). And in August 2016. the “no-name” tropical disturbance over Louisiana delivered over 31 inches of rain. killing 13 and leaving $14 billion in damage (USD 2026).

The same region that remembers those disasters is also, in another way, desperate for relief—if it can be delivered safely.

While the coming rains would ideally not be extreme, the update said they offer drought relief. Short-term drought data were described as showing much of the region has pulled out of a months-long drought that peaked in March. But a years-long precipitation deficit has depleted groundwater and reservoirs.

That depletion has already pushed water decisions. The city of Corpus Christi, the update said, considered emergency water restrictions this summer. As of June 13. the central and upper Texas coast needed 19–20 inches of rain in just one month to pull out of intense long-term drought conditions. according to NOAA. Florida—outside of the Panhandle—needed 20–26 inches.

A May 20 story in Inside Climate News was cited for details about reservoirs: it reported that Corpus Christi’s largest water source. the Choke Canyon Reservoir. hasn’t been full since 2008. and that it “has received three minor inflow events and zero major inflow in the last 15 years. ” according to Texas state climatologist John Nielsen-Gammon. The next-largest reservoir. Lake Corpus Christi. “hasn’t logged inflows in five years.” The two reservoirs combined are about 8 percent full.

In contrast, further south and west, Mexico’s drought outlook is improving. The update said that in recent weeks the fraction of Mexico experiencing abnormal dryness or drought dropped to around 15 percent—its lowest value since 2015—after generous rains so far this year brought drought relief.

Back along the Texas coast. the immediate message remains the same: residents should prepare for heavy rainfall and the real risk of fast-developing flooding as Potential Tropical Cyclone One—Invest 90L—moves from a near-land disturbance toward a possible brief time over Gulf waters later Tuesday or Wednesday.

Texas coast Potential Tropical Cyclone One Invest 90L tropical storm watch flooding Corpus Christi Gulf Coast NOAA drought relief Waco I-35