Radar image of Hurricane Eta at 11 p.m. EST Sunday, November 8, 2020, as the storm was making landfall in the Florida Keys. (Image credit: Mark Nissenbaum/Florida State University)

Tropical Storm Eta made landfall on Lower Matecumbe Key in the Florida Keys around 11 p.m. EST Sunday, November 8, with maximum winds of 65 mph and a central pressure of 991 mb. Eta was the record 12th named storm to make landfall in the U.S. in 2020, and the first in Florida. Near the time of landfall, a WeatherFlow station at Carysfort Reef Light in the Florida Keys reported a sustained wind of 52 mph with a gust of 63 mph, and another Weatherflow station in Key Largo reported a wind gust of 53 mph.

Over a foot of rain in Florida

Persistent rainbands from Eta set up over portions of southern and central Florida this past weekend, resulting in torrential rains that caused widespread urban flooding. The heaviest rains, in excess of a foot, fell in Broward County, where Fort Lauderdale is located (see the tweet from National Hurricane Center forecaster Eric Blake). Some top 48-hour rainfall amounts reported by the National Weather Service for Florida, as of 6 a.m. EST Monday, November 9:

15.79 inches, Miramar;
14.24 inches, Hollywood;
12.95 inches, Pembroke Pines;
9.40 inches, Fort Lauderdale;
6.57 inches, Boca Raton;
6.21 inches, Miami Beach; and
5.48 inches, Miami.

Figure 1. Rainfall amounts for the 48-hour period ending at 7 a.m. EST Monday, November 9. Eta dumped over 14 inches of rain (turquoise colors) in southern Florida. (Image credit: NOAA)

Eta’s winds and gusts

Strong winds from Eta affected much of the southern Florida coast on Sunday, knocking out power to over 200,000 customers at various times. As of 11 a.m. EST Monday, power had been restored to all but 40,000 customers, according to poweroutage.us. Here are some of the top wind gusts as of 6 a.m. EST Monday, November 9, according to the NWS:

69 mph, Diana Beach;
66 mph, Fort Lauderdale;
56 mph, Pompano Beach;
55 mph, Boca Raton;
54 mph, Naples;
53 mph, West Palm Beach;
53 mph, Pembroke Pines; and
51 mph, Miami.

Moderate coastal flooding from a two-foot storm surge

Eta generated a modest storm surge along the southeast Florida coast near Miami, where onshore winds piled up a storm surge of about two feet. The peak storm flooding occurred near the 2 a.m. EST Monday high-tide cycle, when a storm surge of 2.1 feet brought moderate coastal flooding at Virginia Key, the barrier island to the east of Miami. To the north of Miami, in Broward County, a storm surge of 1.73 feet was observed at South Port Everglades during the Monday morning high tide, resulting in minor coastal flooding. Moderate coastal flooding occurred in the Florida Keys at Vaca Key from a storm surge of 1.68 feet.

Figure 2. Continental U.S. landfalls in 2020. (Image credit: Steve Bowen, Aon)

Eta is record-extending 12th named storm of a season to hit U.S.

Eta is the 12th named storm to make landfall in the U.S. in 2020, leaving the old record of nine U.S. landfalls in a single year, set in 1916, far in the rearview mirror. Third place is jointly held by 2004 and 1985, with eight. Remarkably, Eta was the first of the 2020 landfalls to occur 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.

Forecast for Eta

The counter-clockwise flow of air around an upper-level low pressure system to its southwest will steer Eta to the west-southwest, away from Florida, on Monday. This low is expected to merge with Eta by Tuesday. During this process, wind shear will fall from the high to moderate range, potentially allowing Eta to intensify into a category 1 hurricane. Fueling that intensification, Eta will be over the warm waters of the Loop Current in the southeastern Gulf of Mexico, where ocean temperatures are near 29 degrees Celsius (84°F). However, there is also dry air associated with the trough, and that dry air will continue to affect Eta, potentially putting the brakes on any rapid intensification.

Figure 3. Track forecasts out to eight days for Eta from the 6Z (1 a.m. EST) Monday, November 9, run of the GFS ensemble model (GEFS). The black line is the mean of the 31 ensemble members; individual ensemble member forecasts are the thin lines, color-coded by the central pressure they predict for Eta. After curving west-southwest into the southern Gulf of Mexico, the long-term motion of Eta was highly uncertain. (Image credit: Tropical Tidbits)

Steering currents will be weak once Eta merges with the upper level trough on Tuesday, and it’s not yet clear whether Eta might meander in the Gulf of Mexico all week, as suggested by the GFS model, or be tugged to the north and then northeast later in the week by a trough of low pressure passing to the north, as predicted by the European model. The 10 a.m. EST Monday NHC forecast was a compromise between these extremes. The cone of uncertainty for Eta for its four- to five-day forecast should be considerably larger than the default cone depicted on the official forecast, and substantial changes to the long-term track forecast for Eta are likely by Tuesday.

Figure 4. GeoColor satellite image of Tropical Storm Eta at 11:30 a.m. EST Monday, November 9, 2020. (Image credit: RAMMB/CIRA/Colorado State University)

What if the name Eta needs to be retired?

Hurricane Eta caused a catastrophe in Central America, where at least 130 deaths are being blamed on the storm, with over 100 missing, according to a Monday morning write-up from weather.com. Eta is surely deserving of having its name retired because of its impact on Nicaragua, where it made landfall on November 3 as a category 4 hurricane with 140 mph winds. In addition, Honduras (57 dead), Guatemala (31 dead, over 100 missing), and Panama (17 dead, 62 missing) all suffered enormously from Eta’s rains. However, since the Greek alphabet will likely be needed again in a future Atlantic hurricane season, the name “Eta” cannot be retired.

According to the World Meteorological Organization, if Eta 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 “Eta 2020” and Eta would continue to be used when the Greek alphabet is needed again.

Two other “Greek” named storms from 2020 are already candidates to have their names retired in this fashion. Hurricane Delta made landfall in western Louisiana on October 9 as a category 2 storm with 100 mph winds and killed six people. Insurance broker Aon is estimating that Delta did at least $4 billion in damage to the U.S. Hurricane Zeta, which made landfall in Louisiana on October 28 as a category 2 storm with 110 mph winds, did over $4.4 billion in damage, according to catastrophe risk modeling company Karen Clark & Company. Historically, the names of every hurricane doing at least $3 billion in damage (2020 dollars) 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!).

Figure 5. MODIS visible satellite image of 97L on Monday morning, November 9. (Image credit: NASA Worldview)

Invest 97L in the northeastern Atlantic close to tropical storm status

A non-tropical low-pressure system that developed on Sunday in the central Atlantic, several hundred miles southwest of the Azores Islands, has been designated 97L by NOAA’s National Hurricane Center. The system was headed east-northeast at about 5 – 10 mph, and had marginal conditions for development, with sea surface temperatures (SSTs) near 25.5 degrees Celsius (78°F), high wind shear of 30 – 45 knots, and a dry atmosphere with a mid-level relative humidity of 50%.

However, temperatures in the upper atmosphere were quite cold – about seven degrees Celsius colder than what Tropical Storm Eta is currently experiencing, creating high instability for 97L and increasing the system’s heavy thunderstorm activity. Satellite images early Monday afternoon showed that 97L had a well-defined surface circulation, and a modest amount of heavy thunderstorm activity near its center of circulation, suggesting that the system was close to tropical storm status.

The top three models for predicting tropical cyclone genesis gave 97L modest support for development, and predicted an east-northeast motion through the end of the week, taking 97L between the Azores Islands and Canary Islands, toward Portugal. In a 1 p.m. EST Monday Tropical Weather Outlook, NHC gave 97L two-day and five-day odds of development of 70% and 80%, respectively. The next name on the Atlantic list of storms is Theta, the eighth letter in the Greek alphabet. Theta would be the 29th named storm of the 2020 Atlantic hurricane season, breaking the record of 28, currently shared by the 2020 season with the 2005 season.

Eta regains tropical storm status, heads for Florida after causing devastation in Central America

Another area of concern the NHC is monitoring for development is in the central Caribbean, where a tropical wave is expected to merge with a larger area of low pressure later in the week. The top three models for predicting tropical cyclone genesis were giving this future disturbance modest support for development. In a 1 p.m. EST Monday Tropical Weather Outlook, NHC gave this future system two-day and five-day odds of development of 0% and 50%, respectively.

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Posted on November 9, 2020(1:56pm EST).

Jeff Masters, Ph.D.

Jeff 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 safer passion -...