Jeff Masters Weather Blog

Nicholas brings debris, storm surge to Texas as Cat 1 hurricane » Yale Climate Connections

Hurricane Nicholas made landfall along the central Texas coast at 1:30 a.m. EDT Tuesday, September 14, as a category 1 storm with 75 mph winds. In the 24 hours ending at 11 p.m. EDT Monday, Nicholas intensified by 35 mph, meeting the National Hurricane Center’s minimum definition of rapid intensification (a 35 mph increase in winds in 24 hours).

Five out of six of this year’s Atlantic hurricanes have rapidly intensified by at least 35 mph in 24 hours, with only Hurricane Henri missing the mark:

Nicholas: 35 mph ending at 3Z Sep. 14
Larry: 45 mph ending at 3Z Sep. 4
Ida: 65 mph ending at 15Z Aug. 29
Grace: 55 mph ending at 6Z Aug. 21
Elsa: 35 mph ending at 12Z Jul. 2

Nicholas is 19th U.S. landfalling storm in two years, 8th of 2021

With hurricane season just half over (September 10 is the climatological half-way point of the season), Nicholas is already the eighth named storm and second hurricane to make landfall in the contiguous U.S. this year. Since May 2020, the U.S. has experienced a truly astonishing 19 landfalls by named storms (including Nicholas). Seven of these landfalls were in Louisiana.

The U.S. landfall pace in 2021 is now ahead of the record year of 2020, when a remarkable 11 named storms made landfall in the contiguous U.S. The eighth landfall of 2020 (Tropical Storm Beta in Texas) occurred on September 21.

From 1950 through 2020, the U.S. averaged three land-falling tropical storms (with one a hurricane) per year, so 2021 already has more than two average seasons’ worth of land-falling storms.

Here are the 2021 U.S. landfalls, with deaths and preliminary damages from Aon (except for Ida, where the preliminary damages are from Core Logic):

Nicholas: landfall in Texas on September 14 with 75 mph winds; no deaths yet reported;
landfall in Florida on September 9 with 45 mph winds, no deaths and negligible damage;
 landfall in Louisiana on August 29 with 150 mph winds, killing 66 and causing $43-$64 billion in damage;
Henri: landfall in Rhode Island on August 22 with 60 mph winds, killing two and causing over $550 million in damage;
Fred: landfall in Florida on August 16 with 65 mph winds, killing seven and causing $1.1 billion in damage;
Elsa: landfall in Florida on July 7 with 65 mph winds, killing one and causing $775 million in damage;
Danny: landfall in South Carolina on June 28 with 45 mph winds, no deaths or damages reported;
Claudette: landfall in Louisiana on June 19 with 45 mph winds, killing 14 and causing $350 million in damage. (One could argue Claudette did not count as a landfall, since it wasn’t named until it was centered over land.)

Figure 1. Radar-estimated rainfall from Nicholas as of 11:32 a.m. EDT Tuesday, September 14. Widespread rainfall amounts of five to eight inches (orange and red colors) had fallen along the central and northeast Texas coast. (Image credit: Weather Underground, an IBM business)

Nicholas brings wind gusts to 95 mph, rains of 9”, and storm surge of 5’ to Texas

According to the 11 a.m. EDT Tuesday NOAA storm summary, the top wind gust from Nicholas was 95 mph at a WeatherFlow station at Matagorda Bay, which also reported sustained winds of 76 mph – apparently the only report of hurricane-strength sustained wind received from Nicholas over land. It is not uncommon for minimal hurricanes to produce few (if any) reports of hurricane-strength sustained winds at landfall, for a variety of reasons detailed in this 2018 analysis.

Three other wind gusts in excess of hurricane force were also recorded: 81 mph at the Brazos 451 Oil Platform, 78 mph 13 miles east-southeast of Magnolia Beach, and 77 mph at Palacios.

The heaviest rains from Nicholas have fallen along the central Texas coast, with 9.85 inches reported at the Houston suburb of Deer Park as of 11 a.m. EDT Tuesday. Downtown Houston received 6.60 inches.

According to the storm surge tracker page at the Southern Regional Climate Center, the top storm surge at any NOAA tide gauge was 5.58 feet at Manchester, the fourth-highest water level on record there, dating back to 1995. Twelve gauges along the Texas coast recorded a storm surge between three and six feet. As of 11 a.m. EDT Tuesday, storm surge levels had fallen below three feet at all but one tide gauge (3.14 feet at Rollover Pass, Texas).

At 11 a.m. EDT Tuesday, Nicholas was centered about 10 miles southeast of Houston, Texas. Nicholas was moving northeast at 6 mph with top sustained winds of 45 mph, bringing heavy rains to most of the central Texas and southwest Louisiana coasts. Nicholas will likely weaken to a tropical depression Tuesday night, and become a rainy remnant low over southern Louisiana on Wednesday. Additional heavy rains of 5-10 inches over portions of coastal Texas and Louisiana are likely to cause damaging flash flooding and river flooding through Wednesday. Nicholas has caused power outages to over 500,000 customers in Texas.

Disturbance 95L near Africa one to watch

A tropical wave off the coast of Africa, about 400 miles southeast of the southern Cabo Verde Islands at 8 a.m. EDT Monday morning, was headed west at 15 mph. This wave, which NHC designated as 95L, has good model support for development, though not as strong as on Monday. Satellite imagery showed that 95L was well-organized, with a developing surface circulation and modest area of heavy thunderstorms.

Figure 2. MODIS visible satellite image of 95L along the coast of Africa on Tuesday morning, September 14, 2021. (Image credit: NASA Worldview)

95L will have favorable conditions for development this week, with warm sea surface temperatures near 28 degrees Celsius (82°F), mostly moderate wind shear of 10-20 knots, and a moist atmosphere with a mid-level relative humidity of 60-75%. However, 95L is expected to face a major obstacle to further intensification early next week, when it approaches the Leeward Islands, as a result of a large upper-level trough of low pressure. This trough is predicted to have high wind shear and dry air, and many model forecasts have 95L weakening significantly by early next week when it encounters the trough.

There is much uncertainty with forecasts this far in advance, and the impacts 95L might pose to the Caribbean islands or North America remain to be seen. In its 8 a.m. EDT Tuesday Tropical Weather Outlook, the NHC gave 95L 2-day and 5-day odds of development of 70% and 90%, respectively. The next name on the Atlantic list of storms is Odette.

Figure 3. Infrared satellite image of disturbance 96L at 1450Z (10:50 a.m. EDT) Tuesday, September 14, 2021. (Image credit: RAMMB/CIRA/CSU)

Disturbance 96L bears watching over northwestern Atlantic

Models are showing increased support for a potential tropical depression or tropical storm that could be scooting across the northwestern Atlantic over the next few days. On Tuesday morning, the NHC designated disturbance 96L, placing it about 200 miles north of the Turks and Caicos Islands. 96L encompassed a broad area of showers and thunderstorms (convection) that was gradually increasing in extent. The first run to be carried out by the SHIPS statistical model on 96L (12Z Tuesday) showed 96L developing into a robust tropical storm over the next couple of days, and conditions do appear quite favorable for development through at least Thursday once 96L has a low-level center of circulation around which it can consolidate. Wind shear is projected to be low (less than 5 knots), with very warm SSTs (around 30 degrees C or 86°F) and a moist mid-level atmosphere (relative humidity around 65-70%). Satellite imagery Tuesday afternoon showed 96L was poorly organized, but there was a steady increase in the intensity and areal coverage of its heavy thunderstorms.

In its 8 a.m. EDT Tuesday Tropical Weather Outlook, the NHC gave 96L a 30% chance of becoming at least a tropical depression by Thursday and a 60% chance through Sunday. We expect those odds to rise. The first hurricane hunter aircraft is scheduled to investigate 96L on Wednesday afternoon.

Both the European and GFS ensemble runs now have a few members bringing 96L to at least tropical storm strength. As has been the case with this system for days, the GFS ensemble is more bullish on the likelihood of development. The ensembles are most emphatic on development from Thursday onward, when they project 96L will be moving northward and northeastward, remaining several hundred miles off the U.S. East Coast. Wind shear will be increasing by this point, though, and eventually 96L will reach cooler waters. Weak westerly flow at upper levels across the northeastern U.S. this weekend should be sufficient to keep 96L offshore. However, 96L could linger southeast of New England for several days next week as a strong upper ridge builds across the area, blocking the system from recurvature to the northeast.

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