Beryl slowly reorganizing over the Gulf or Mexico » Yale Climate Connections

Tropical Storm Beryl is gradually reorganizing over the warm waters of the Gulf of Mexico, after a 15-hour trek over the Yucatan Peninsula on Friday knocked the stuffing out of the former category 5 hurricane. At 11 a.m. EDT Saturday, Beryl was a tropical storm with 60 mph winds and a central pressure of 997 mb, located about 460 miles southeast of Corpus Christi, Texas, headed west-northwest at 12 mph. Hurricane watches, storm surge watches, and tropical storm warnings were up for a large swath of the Texas and northeastern Mexico coasts.

Waking up Saturday morning to see Beryl not overachieving (for a change!) was a welcome sight. Beryl’s disorganization greatly reduces the chances of a worst-case scenario of landfall as a major hurricane.

Overnight, Beryl gulped in a large helping of the dry air which lies over the southwestern Gulf of Mexico. This dry air was driven into the core of Beryl by strong upper-level winds from the south-southwest, which were creating a high 15-25 knots of wind shear. Also keeping Beryl subdued were some of the coolest waters the storm has seen on its long traverse of the Atlantic: the shelf waters of the Yucatan Peninsula, running about 28.5 degrees Celsius (83°F) with a low oceanic heat content.

Satellite imagery early Saturday afternoon showed that Beryl’s heaviest thunderstorms were on the northwest side of the center, away from the dry air to the south. These thunderstorms were growing in intensity and areal coverage, a sign of intensification. However, the Hurricane Hunters found that Beryl’s central pressure was remaining roughly constant late Saturday morning, and the 11 a.m. discussion from NHC commented that the blow-up of thunderstorms may subside later on Saturday.

Track forecast for Beryl

There is increased confidence this afternoon in the forecast of Beryl’s upcoming track. The models are in better agreement on how the storm will respond to a change in steering currents imparted by a broad trough of low pressure sweeping across the central U.S.; the south-to-north upper-level winds along the eastern edge of this trough will turn Beryl to the northwest on Saturday night and then north-northwest by Sunday night, resulting in the storm making landfall on the Texas coast on Monday morning.

The 6Z Saturday runs of the four high-resolution hurricane models, plus the GFS and Europeans models, predicted a landfall could occur as far south as Corpus Christi or as far north as Matagorda Bay. A stronger storm will tend to make a landfall farther to the north. This occurs because a stronger hurricane is taller and will feel a more northward pull from the upper-level winds of the trough.

Intensity forecast for Beryl

Conditions in the Gulf of Mexico are expected to grow more favorable for intensification over the next two days. Wind shear is forecast to drop from 15 knots on Saturday afternoon to the low range, 5-10 knots, by Sunday. This drop in shear should allow Beryl to wall off the dry air to its south by Sunday and rebuild an eyewall. Sea surface temperatures along Beryl’s path will increase from 29 degrees Celsius (84°F) on Saturday to 30 degrees Celsius (86°F) on Sunday, as Beryl approaches Texas. However, the total heat energy of the ocean waters is much lower than what Beryl had to work with in the western Caribbean – mostly around 40 kJ/cm^2, compared to as high as 150 kJ/cm^2 near Jamaica.

The official NHC forecast from 11 a.m. EDT Saturday calls for Beryl to make landfall in Texas Monday morning as an intensifying high-end category 1 hurricane with 85 mph winds. However, this intensity forecast probably has an uncertainty of plus or minus one Saffir-Simpson category.

As of Saturday morning (6Z), NOAA’s four hurricane-tailored intensity models showed a variety of landfall intensities for Beryl (see Tweet above), ranging from a strong tropical storm to a strong category 1 hurricane. The 12Z Saturday SHIPS model gave a 14% chance of Beryl becoming a category 3 hurricane with 120 mph winds by Monday morning. Beryl is not a large storm, which increases its odds of making rapid intensity changes.

Bottom line: It is likely that Beryl will make landfall in Texas on Monday as a rapidly intensifying hurricane, most likely as a Cat 1 or Cat 2, but landfall as a major Cat 3 is looking less likely.

Flood threat

Torrential rains (perhaps a foot or more locally) will spread into central Texas late Sunday into Monday, with a corridor of 8-12 inches likely (Fig. 1), with localized totals of 15 inches. Unfortunately, the heaviest rains will miss the drought-parched areas of southwest Texas, and will impact areas with wet soils prone to flooding.

One specific concern is Lake Livingston Dam, on a reservoir about 90 miles north-northeast of Houston that provides the majority of the city’s water. The surrounding watershed is predicted to receive 4-6 inches of rain from Beryl (Fig. 1). This dam was placed under a “potential failure watch” by the Trinity River Authority on June 28 following weeks of heavy rain. The agency reported no immediate danger of a failure or breach as of Tuesday while repairs proceeded. On Thursday, based on satellite imagery, a London-based firm reported detecting “significant deformation” of two areas of the dam.

Wind, tornado, and riptide risk

High winds will likely be the main damaging threat from Beryl. As usual, the most damaging winds will occur along the coast near and to the right of where the eye crosses the coast. Two potential mitigating factors are at hand with Beryl: it is not expected to arrive as an especially large hurricane, and its predicted angle of approach to the curved coastline means that the area of strongest winds to the right of the center would remain largely offshore until after landfall, as opposed to a more perpendicular and direct landfall.

In its two- and three-day severe-weather outlooks issued Saturday morning, NOAA’s Storm Prediction Center called for a Slight Risk of tornadoes (level two out of five on their five-tiered risk scale) on both Sunday and Monday. The main risk would be to the right of where the center makes landfall, where the wind shear supportive of rotating storms and tornadoes will be maximized.

High surf and rip currents can be expected to develop well north of Beryl along the western U.S. Gulf Coast this holiday weekend.

Storm surge threat

Since Beryl is starting out as a medium-sized tropical storm with only two days until landfall, it will not be able to pile up a huge storm surge. NHC is calling for a peak surge of 3-5 feet near and to the right of where the eye crosses the coast. While a surge of this magnitude will cause moderate coastal flooding, beach erosion, and some damage, it will be a far cry from the devastating 17-foot storm surge that category 2 Hurricane Ike of 2008 brought to the coast northeast of Galveston.

Tidal range between low tide and high tide near the expected landfall location is only about 0.5 feet, so the timing of Beryl’s arrival with respect to high tide will be relatively unimportant. NOAA’s Tides and Currents website showed that water levels at Rockport, located about 20 miles northeast of Corpus Christi, were running about 0.25 feet above normal on Saturday afternoon. Rockport, which has records extending back to 1948, experienced its second-highest water level on record on August 26, 2017, during the landfall of category 4 Hurricane Harvey. Their record of 3.73 feet above mean higher high water (MHHW) was set on August 10, 1980, during Hurricane Allen.

For more coverage of Beryl, we recommend The Eyewall, written by Texas-based editors Matt Lanza and Eric Berger.