The remnants of the storm system that forecasters worried might grow into the 2021 Atlantic hurricane season's first tropical storm steadily disintegrated on Saturday after making landfall north of Corpus Christi and moving into Central Texas.
The National Weather Service warned that the San Antonio area could receive up to an inch and half of rain through Tuesday as the storm system — originally designated Invest 91L — slowly fell apart over the region. Slightly higher rainfall amounts were expected during the same timeframe to the north and east of the city.
Forecasters said there was a very low risk of isolated tornadoes through 6 p.m. Saturday, east of the weakening storm system or north of a line from Fredericksburg to New Braunfels to La Grange.
Downtown San Antonio resembled a humid Caribbean city on Saturday, quickly alternating between warm sunshine and springtime breezes to dark-gray skies and heavy downpours.
Scattered showers & isolated thunderstorms tonight, mainly east of I-35. Low temps in the upper 60s to low 70s. Rain chances remain high through Tuesday, especially for areas east of I-35, before tapering off Wednesday. Dry weather sets in on Thursday. pic.twitter.com/nD5CsSkE1O
— NWS Austin/San Antonio (@NWSSanAntonio) May 22, 2021
Rivers and creeks southeast of San Antonio swelled because of the latest rainfall. The Guadalupe River was expected to crest around six feet above flood stage at Victoria by Saturday night, causing minor lowland flooding near a golf course and events center.
Forecasters added that cattle along some stretches of the the river could be cut off by floodwaters and need to be fed from boats. The river was expected to dip below flood stage at Victoria early Monday.
The weather service also warned dangerous rip currents were expected to continue through Sunday off the Gulf Coast.
Interesting last 24 h w/ Invest #91L in the Gulf of Mexico.
— Philippe Papin (@pppapin) May 22, 2021
The system had a closed llvl vortex & 25-30 kt winds, but it lacked sufficient organized deep convection to be classified as a TC.
Now well inland over Texas, but still has skeletal low-level banding on radar. pic.twitter.com/CiXhneieio
The sudden emergence of the Gulf storm system on Friday, less than two weeks before the 2021 hurricane season begins on June 1, was an ominous reminder of the 2020 hurricane season, the most active season on record.
Weather experts on Friday warned that 91L could briefly grow into a tropical storm before making landfall on Saturday, thereby earning the first name from the National Hurricane Center.
Instead, that distinction went to Invest 90L, a storm in the Atlantic that grew northeast of Bermuda. Subtropical Storm Ana formed overnight and swirled further into the ocean, posing no threat to land.
The National Weather Service's Houston office tweeted, "This makes the 7th consecutive year of a system forming before the official start of the Atlantic hurricane season (June 1st)."
As of Saturday, Ana had winds of 40 mph, and it was expected to weaken in the coming days as it moved over cooler waters.
The National Hurricane Center explained, "Unlike tropical cyclones, subtropical cyclones derive a significant proportion of their energy from baroclinic sources, and are generally cold-core in the upper troposphere, often being associated with an upper-level low or trough."
A tropical storm is typically born over warm waters, forms a tight warm core and has the potential to grow into a hurricane.
A subtropical storm, like Ana, is usually at first just a swirling element of a larger weather system that sees a clash of cold and warm air, which fuels its development. It typically has little storm activity at its cold center and is much more spread out, but it comes with strong and dangerous winds.
It earns the "tropical" part of its name when it draws strength from warmer waters and thunderstorms begin to grow at its center. It begins to resemble the better-known tropical storms.
Subtropical Storm #Ana latest satellite view near #Bermuda pic.twitter.com/E3BQWL9fZv
— Zoom Earth (@zoom_earth) May 22, 2021
The storms emerged only a day after the National Oceanic and Atmospheric Administration, or NOAA, issued its outlook for the 2021 season.
Following the drama of the 2020 season, the NOAA predicted more storms than usual in 2021.
Forecasters anticipated 13 to 20 named storms with top winds at least 39 mph. Of that number, they expected 6 to 10 would become hurricanes with top winds of least 74 mph.
"This includes 3-5 major hurricanes ranked as category 3, 4 or 5 with top winds of at least 111 mph," explained Ben Friedman, the acting NOAA administrator.
NOAA added that climate change has not been linked to the frequency of named storms, but has been linked to an increase in intensity of storms and increased rainfall.
Jerry Clayton contributed to this report.
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