Beta radar image
Radar image of Tropical Storm Beta at 12:38 p.m. EDT Monday, September 21, 2020, as the storm approached the Texas coast. (Image credit: Mark Nissenbaum/Florida State University)

Tropical Storm Beta was spreading heavy rains over coastal Texas and Louisiana on Monday as it trekked slowly west-northwestward at less than 7 mph toward an expected landfall in Texas on Monday night. Though Beta was not predicted to intensify, its slow movement will make it capable of bringing widespread torrential rains of 5 – 10 inches and damaging flooding to the coast.

Figure 1
Figure 1. The end of the 61st Street Pier in Galveston, Texas sheared off due to the storm surge and high waves of Tropical Storm Beta near 10 p.m. CDT Sunday, September 20, as seen in this video. (Image credit:

At 2 p.m. EDT Monday, September 21, Beta was 45 miles southeast of Port O’Connor, Texas, heading west-northwest at 7 mph with maximum sustained winds of 45 mph and a central pressure of 999 mb. Heavy rains from Beta were affecting much of the Texas and Louisiana coasts, with the heaviest rains of 4 – 8 inches having fallen over coastal Louisiana near the mouth of the Mississippi River. Rainfall amounts along the Texas coast were generally 1 – 3 inches.

The live storm surge tracker at Trabus Technologies showed Beta was bringing storm surge heights of two to four feet along much of the Texas and Louisiana coast. The maximum storm surge heights observed as of 2 p.m. EDT Monday were:

3.9 feet: Shell Beach, Louisiana (east-southeast of New Orleans);
3.5 feet: San Luis Pass, Texas (south of Houston);
3.5 feet: Matagorda Bay, Texas (southwest of Houston); and
3.1 feet: Rollover Pass, Texas (east of Houston).

Figure 2
Figure 2. GeoColor satellite image of Tropical Storm Beta (left) at 11:30 a.m. EDT Monday, September 21. NHC gave an area of disturbed weather off the southeast coast of Florida (right) five-day odds of development of 20%. (Image credit: RAMMB/CIRA/Colorado State University)

On Monday morning, a TCOON observing site at Port O’Connor, Texas, measured a wind gust of 40 mph in Beta, and a NOAA buoy located just east of Galveston, Texas, reported a sustained wind of 39 mph, gusting to 43 mph.

Beta was feeding off of very warm ocean waters in the western Gulf of Mexico that were 29 – 30 Celsius (84 – 86°F), about 0.6 Celsius (1°F) above average. Typically, such warm waters would provide Beta with an unusually high amount of moisture for producing heavy rains. However, satellite images showed Beta was fighting moderately high wind shear and dry air at upper levels, and this was keeping heavy thunderstorm activity limited.

Figure 3
Figure 3. Track forecasts out to six days for Tropical Storm Beta from the 6Z (2 a.m. EDT) Monday, September 21, run of the new version of the GFS ensemble model (which is not yet operational). The black line is the mean of the various ensemble members; the individual ensemble member forecasts are the thin lines, color-coded by the central pressure they predict for Beta. (Image credit: Tropical Tidbits)

Forecast for Beta

Conditions for further development are expected to be marginal through landfall, with moderately high wind shear of 15 – 20 knots and dry air continuing to hinder Beta.

The model consensus is that Beta will make landfall in Texas on Monday night and penetrate inland no more than 50 miles by Tuesday, as the ridge of high-pressure steering Beta weakens and puts the storm in an area of weak steering currents. A weak trough of low pressure to the north then is expected to take over steering Beta, inducing a slow east-northeast to northeast motion, roughly parallel to the coast.

Figure 4
Figure 4. Rainfall forecast for the five days ending at 7 a.m. CDT September 26. Beta is predicted to dump additional rains of six to ten inches over portions of Texas and Louisiana. (Image credit: NOAA/NHC)

Beta’s track during this period likely will be just inland. However, if Beta’s track takes it back over water near the upper Texas coast, it might rejuvenate slightly and dump heavier rains than currently predicted over coastal Texas and Louisiana. Given its very slow motion and the very warm Gulf waters feeding it, Beta could end up being a prodigious rainmaker, and flooding due to its heavy rains will be the chief damaging impact of the storm. Fortunately, the type of widespread biblical rainfall seen in this region with Hurricane Harvey is not expected.

Figure 5
Figure 5. GeoColor satellite image of Hurricane Teddy at 11:30 a.m. EDT Monday, September 21. (Image credit: RAMMB/CIRA/Colorado State University)

Category 1 Teddy brushing Bermuda; Nova Scotia and Newfoundland landfalls expected on Wednesday

At 2 p.m. EDT Monday, Hurricane Teddy had weakened to a category 1 storm with top sustained winds of 90 mph and a central pressure of 960 mb. Teddy was headed north-northeast at 18 mph as a large hurricane, with tropical storm-force winds extending out up to 230 miles from the center.

Figure 6
Figure 6. Hurricane Teddy as seen on Bermuda radar at 10:42 a.m. EDT September 21, 2020. (Image credit: Bermuda Weather Service)

Teddy’s gigantic wind field had created waves 12 feet high spanning an area of ocean 1,070 miles across, with waves 35 feet high near the center. The hurricane was generating big swells and dangerous surf conditions and riptides along much of the southeastern U.S. East Coast, with waves of 10 – 15 feet common in the offshore waters. Waves up to 20 feet high were battering Bermuda, along with heavy rain squalls and winds gusting to tropical storm-force.

Forecast for Teddy

As Teddy interacts with the trough of low pressure steering it to the north, the hurricane will absorb energy from the trough, and likely intensify by Tuesday night into a category 2 hurricane with 105 mph winds, despite an expected increase in wind shear. Teddy’s wind field will expand, and is predicted to extend out up to 450 miles from the center by Tuesday evening. Teddy’s wave field will expand and amplify in response, with NOAA’s WaveWatch 3 model predicting that Teddy on Tuesday will create waves over 50 feet high across an area over 100 miles in diameter. Dangerous surf conditions will intensify along the mid-Atlantic, New England, and Atlantic Canada coasts through Wednesday.

Also see: Unusually warm sea temperatures fueled Harvey’s devastating rains

Once Teddy encounters the cooler waters north of the Gulf Stream, at the latitude of New Jersey, steady weakening should occur, but Teddy will maintain a very large wind field as it transitions to an extratropical storm. Teddy is likely to pass near or over northeastern Nova Scotia on Wednesday morning, with a second landfall later on Wednesday expected in Newfoundland. Landfall in Nova Scotia likely will be as a strong extratropical storm with winds of 60 – 75 mph, with heavy rain and widespread gale-force winds likely the main threat.

Bob Henson contributed to this post.

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Posted on September 21, 2020 (2:52pm, EDT)

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...

11 replies on “Unusually warm ocean waters fuel Tropical Storm Beta’s torrential rains”

  1. So since Beta has now made landfall, any chance that will lessen the onshore flow and rain to points east? It’s been raining in New Orleans and southern Mississippi for 4 days.

  2. “Figure 1. The end of the 61st Street Pier in Galveston, Texas sheared off due to the storm surge and high waves of Tropical Storm Beta near 10 p.m. CDT Monday, September 21, as seen in this video. (Image credit:”

    Um, I’m reading this at 7:50 p.m. CDT Monday, September 21.

    ETA: Video says September 20, of course.

    Also, from followup on Twitter: “Owner says pier was already damaged, so they purposefully cut end to prevent further damage.”

  3. Landfall in Nova Scotia likely will be as a strong extratropical storm with winds of 60 – 75 mph, with heavy rain and widespread gale-force winds likely the main threat.”

    I bet the History Channel will get some mileage out of this on their “Curse of Oak Island” series!

  4. Thank You for the Update Dr. Masters; this issue of steering current collapse causing prolonged flooding underneath a slow moving storm coming ashore somewhere on the Gulf Coast from Texas to the Florida Panhandle is becoming a more frequent occurrence almost every season now with several storms at some point.

  5. Always informative! Thanks, Doc!

    (minor note: I think Figure 1 should be dated Sunday, September 20.)

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