Hurricane Zeta made landfall at 4 p.m. CDT Wednesday, October 28, 2020, in southeastern Louisiana near Cocodrie as a high-end category 2 storm with 110 mph winds and a central pressure of 970 mb. Zeta is the strongest hurricane to make a U.S. landfall this late in the year since an October 31, 1899, hurricane (also a category 2 storm with 110 mph winds) hit Myrtle Beach, South Carolina.

At least three deaths are being blamed on Zeta. The hurricane did extensive roof, tree, and power pole damage well inland along its path. See this video of a home losing its roof in the New Orleans suburb of Chalmette, and a video from WDSU taken on Grand Isle, a barrier island near where Zeta made its initial landfall, showing large homes with their roofs torn off, a crumpled gas station canopy, and downed utility poles and wires.

A few collapsed buildings were reported in Louisiana from Zeta’s winds, including an apartment building that partially collapsed in Terrytown, injuring one person. For more detail on Zeta’s impacts, see the weather.com story on the storm.

Zeta’s winds and gusts

The primary damage from Zeta’s landfall was due to the hurricane’s winds, which gusted over 100 mph at numerous locations, helping cause the second largest power outage of the year in the U.S.: About 2.6 million customers were without power Thursday morning. The top power outage of 2020 occurred in August, when Hurricane Isaias knocked out power to 6.8 customers, including 400,000 in PUerto Rico. According to the National Weather Service in New Orleans, these were the top winds recorded during Zeta’s landfall:

112 mph – Bayou Bienvenue, LA;
104 mph – Bay Waveland Yacht Club, MS;
101 mph – Gulfport, MS;
101 mph – Shell Beach, LA; and
100 mph – Laplace, LA.

An oil rig maintained by Louisiana Offshore Oil Port recorded a wave height of 49.9 feet on Wednesday afternoon during the passage of Zeta’s eyewall; an automated camera on the rig caught the impressive waves in this video.

Limited rainfall amounts

With Zeta’s very rapid forward speed of 24 mph at landfall and subsequent acceleration, the hurricane dumped relatively low amounts of rain along its path: just two to five inches, with one small area of six inches near the Mississippi-Alabama border. As of 1 p.m. EDT Thursday, just two river gauges along Zeta’s path were reporting minor flooding, and there were no reports of moderate or major flooding.

A significant storm surge

Zeta generated a significant storm surge along the Louisiana, Mississippi, and Alabama coasts near and to the right of where the center came ashore, and also in Lake Pontchartrain, to the north of New Orleans. The live storm surge tracker at Trabus Technologies (https://surge.trabus.net/) documented these top storm surge heights from Zeta:

Waveland, MS: 8.7 feet;
Pascagoula, MS: 7.4 feet;
Bayou La Batre, AL: 7.2 feet; and
Mobile, AL: 6.2 feet.

Zeta is record-breaking 11th named storm of a season to hit U.S.

Zeta is the 11th named storm to make landfall in the U.S. in 2020, beating the record of nine U.S. landfalls in a single year, set in 1916. Third place is jointly held by 2004, and 1985, with eight. Remarkably, none of the 2020 landfalls have occurred in Florida, which is the most hurricane-prone state. From 1851 through 2019, the U.S. averaged 3.2 named storm landfalls per year, 1.6 hurricane landfalls, and 0.5 major hurricane landfalls.

What if the name Zeta needs to be retired?

The price tag for Hurricane Zeta’s impact in the U.S. will undoubtedly be in the billions of dollars, making Zeta deserving of having its name retired. However, since the Greek alphabet will likely be needed again in a future Atlantic hurricane season, the name “Zeta” cannot be retired.

According to the World Meteorological Organization, if Zeta needs to be retired from the list of hurricane names as a result of its impact on Mexico and the U.S., it would be retired as “Zeta 2020” and Zeta would continue to be used when the Greek alphabet is needed again.

Delta, which made landfall in western Louisiana on October 9 as a category 2 storm with 100 mph winds, is already a candidate to have its name retired in this fashion. Insurance broker RMS is estimating that Delta did up to $5 billion in insured damage to the U.S. and Mexico, and additional billions in uninsured damage may yet add to that hefty price tag. Historically, the names of every hurricane doing at least $3 billion in damage have been retired.

Since the Greek alphabet has 24 letters, it is highly unlikely that 2020 will reach “Omega” and exhaust the list of Greek names (45 named storms!). If that does happen, Randall Munroe, who creates the xkcd comic (https://xkcd.com/944/), proposes that we use random dictionary words.

Expect an active November in the Atlantic

While many no doubt are eager for the 2020 Atlantic hurricane season to be done, it is not ready to be done with us. Three factors point to a potentially active November:

1) Ocean temperatures are about 0.6 degrees Celsius (1.0°F) above average in the Caribbean, southern Gulf of Mexico, and waters near the Bahamas, the primary breeding grounds for late-season tropical cyclones.

2) La Niña conditions strengthened during October, and crossed the threshold for a “strong” event early this week. Strong La Niña conditions typically reduce wind shear over the tropical Atlantic, favoring tropical cyclone formation.

3) The Madden-Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the equator that moves around the globe in 30 – 60 days, now favors tropical cyclone formation in the Atlantic. The MJO will propagate eastwards, and will continue to favor tropical cyclone formation in the Atlantic until mid-November (Figure 8).

*The amount of rising or sinking air in the atmosphere can be inferred from the 200 mb velocity potential (VP) departure from average (also called the anomaly). Negative 200 mb VP anomalies mean that upper-level winds at the 200 mb level are diverging, causing rising air from below to replace the air diverging away at high altitudes. This rising air helps nurture thunderstorm updrafts, and favors low pressure and increased chances of tropical cyclone formation. Conversely, positive 200 mb VP anomalies imply converging air aloft, where sinking air, high pressure, and dry conditions will be unfavorable for tropical cyclone formation. In this plot, negative 200 mb VP anomalies (divergence) are cool-colored contours (the scale shows the departure from average in standard deviations); positive 200 mb VP anomalies (convergence) are warm-colored contours.

Watching a tropical wave moving into the Caribbean

A tropical wave entering the Lesser Antilles Islands on Thursday will be moving west at 10–15 mph through the Caribbean over the coming days. The wave is producing a moderate amount of disorganized heavy thunderstorms, and it is not likely to develop through Friday because of high wind shear.

Forecasts from the GFS and European models have consistently predicted that when this tropical wave pushes into the central Caribbean early next week, it will interact with a large area of low pressure and spawn yet another Caribbean tropical storm. The waters offshore from Nicaragua are predicted to be the most likely formation area.

Also see: September 2020 was the warmest September on record, NOAA reports

The current model consensus is that this potential storm would be trapped to the south of a strong ridge of high pressure and steered westward, with a potential landfall in Nicaragua or Honduras between Monday and Wednesday. However, about 10% of the members of the Thursday morning runs of the European and GFS ensemble models showed that the system could move northwards and be a threat to Cuba late next week.

In a 2 p.m. EDT Thursday Tropical Weather Outlook, NHC gave this system 2-day and 5-day odds of development of 20% and 60%, respectively. The next name on the Atlantic list of storms is the seventh letter in the Greek alphabet, Eta.

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Posted on October 29, 2020 (3:51pm EDT). Edit made on October 30.