The first Atlantic hurricane of the year, Hurricane Elsa, roared through the Caribbean’s Lesser Antilles islands on Friday morning. Elsa intensified into a category 1 storm with 75 mph winds while passing just south of Barbados at 7:15 a.m. EDT Friday. Elsa’s 35-mph increase in winds in the 24 hours ending at 8 a.m. EDT Friday met the National Hurricane Center’s minimum definition of rapid intensification.

The Meteorological Service of Barbados reported sustained winds of 74 mph, gusting to 86 mph, near 7:30 a.m. EDT, as the northern eyewall of Elsa passed over the southern portion of the island. The Barbados airport reported top sustained winds of 63 mph, gusting to 86 mph, at 7:18 a.m. EDT. Elsa brought heavy rains to the island; the highest rainfall amount from the Weather Underground personal weather station network on Barbados was 4.68” as of 11 a.m. EDT Friday.

At 2 p.m. EDT Friday, Elsa was centered 95 miles west-northwest of the island of St. Vincent, speeding west-northwest at 29 mph across the eastern Caribbean. The Hurricane Hunters found that Elsa was continuing to intensify, with top winds of 85 mph and a central pressure of 991 mb.

Elsa had gained some latitude since Thursday, and it was positioned at 13.7°N. This position farther from the equator will help aid development, as will warm sea-surface temperatures near 28 degrees Celsius (82°F), moderate wind shear of 10-20 knots, and a moist atmosphere with a mid-level relative humidity of 65% (though water vapor satellite images showed dry air on the northwest side of the storm getting wrapped into Elsa’s circulation). The main factor discouraging development through Saturday will be Elsa’s rapid forward speed, which will make it difficult for the storm to stay vertically aligned.

Wind damage and flooding are both a concern from Elsa in the Lesser Antilles. Elsa’s heavy rains are particularly a concern on the island of St. Vincent, where ash from a series of eruptions April 9-22 from the Soufrière volcano could potentially mobilize into dangerous mud flows. Radar-estimated rainfall amounts on the island from the Barbados radar were 1-4 inches as of 2 p.m. EDT Friday.

Because of the fast forward speed of Elsa, tropical storm-force winds were mostly confined to the northern side of the center, and areas to the south of the center likely received little wind damage.

Figure 1. Radar image of Elsa at 7:40 a.m. EDT July 2, 2021, as the hurricane’s northern eyewall was affecting Barbados. (Image credit: Weather Service of Barbados)

An unusually early Caribbean hurricane

Elsa is the first hurricane of the 2021 Atlantic hurricane season, and its formation comes more than a month before the average August 10 appearance of the season’s first hurricane (the 1991-2020 average date for the first Atlantic hurricane formation was August 14, according to Phil Klotzbach). Elsa is the earliest-appearing hurricane in nine years, since Hurricane Chris formed 700 miles southeast of Newfoundland on June 21, 2012, according to Brian McNoldy (he doesn’t count Hurricane Alex of January 2016, seeing  that anomalous hurricane as a left-over from the 2015 season). Elsa is the earliest hurricane observed in the Caribbean since Hurricane Alma of May 20, 1970.

A harbinger of an active hurricane season?

It is concerning that Elsa formed early in the season in the main development region (MDR) for hurricanes (between the coast of Africa and Central America, including the Caribbean). A tropical cyclone (the generic term for all hurricanes, tropical storms, and tropical depressions) forming in this region early in the season is typically a harbinger of an active peak part of the season, as it shows the atmosphere and ocean are conducive for activity. In the comments from our previous post, NCHurricane2009 provided a detailed analysis of this, studying the last 13 Atlantic seasons where a tropical cyclone developed in the MDR in June or July. Of these 13 seasons, 10 were active, and only three could be characterized as inactive. The active seasons are highlighted in bold below:

2020: Gonzalo formed in July (30 named storms);
2018: Beryl formed in July (16 named storms; Florence and Michael were high-impact storms);
2017: Bret formed in June; TD 4 and Don formed in July (17 named storms; Harvey, Irma, and Maria were high-impact storms);
– 2014: TD2 formed in July (9 named storms);
– 2013: Chantal formed in July (14 named storms, but only 2 hurricanes, and no major hurricanes);
2008: Bertha formed in July (16 named storms, 8 hurricanes, 5 major hurricanes; Dolly, Gustav, Ike, Omar, and Paloma were high-impact hurricanes);
2005: Dennis, Emily formed in July (28 named storms; Dennis, Emily, Katrina, Rita, Stan, and Wilma were high-impact hurricanes);
2003: TD2 formed in June (16 named storms; Isabel was a high-impact hurricane);
2001: TD2 formed in July (15 named storms)
2000: TD2 formed in June (15 named storms)
1998: Alex formed in July (14 named storms; Bonnie, Georges, and Mitch were high-impact hurricanes);
– 1997: TD5 formed in July (9 named storms); and
1996: Bertha and Cesar formed in July (13 named storms; Fran and Hortense were major-impact hurricanes).

Figure 2. Tracks of all hurricanes observed in the Caribbean in the months of March-July from 1851-2020. A total of 20 early-season hurricanes have been observed. (Image credit: NOAA)

The tropics typically are quiet in July: Since the beginning of the satellite era (1966), there have been 71 tropical storms, 28 hurricanes, and four major hurricanes during July in the Atlantic – an average of one named storm every 1.5 years, one hurricane every two years, and one major hurricane every 14 years (thanks go to Tony Brite for these stats). Since 1851, a total of 20 hurricanes have been observed in the Caribbean in the months of March-July – only about one every eight years (Figure 2).

Figure 3. Predicted wind speed (colors) and sea level pressure (black lines) for Elsa at 8 a.m. EDT (12Z) Sunday, July 4, from the 12Z Friday, July 2, run of the HWRF model. The model predicted Elsa would be affecting Haiti, Jamaica, and Cuba as a low-end category 3 hurricane with 115 mph winds and a central pressure of 969 mb. This intensity forecast is near the high end of what the intensity forecast models are predicting. (Image credit: Tropical Tidbits)

Forecast for Elsa

As it progresses west-northwest at 20-30 mph Friday through Saturday, Elsa will mostly stay south of the dry air from the Saharan Air Layer, though water vapor imagery showed that some dry air on the northwest side of Elsa could interfere with development. Conditions will be favorable for development, according to the 12Z Friday run of the SHIPS model, with moderate wind shear of 10-20 knots and steadily rising sea surface temperatures. Development of Elsa will be favored also by a large-scale region of ascending air over the Atlantic, caused by the passage Friday of an atmospheric disturbance called a Convectively Coupled Kelvin Wave, as explained in a Tweet by Eric Webb.

However, the fast forward speed of Elsa is likely to inhibit development, as fast-moving storms have trouble keeping their cores vertically aligned. The 12Z Friday run of the SHIPS model gave a 28% chance that Elsa would rapidly intensify by 35 mph into a high-end category 2 hurricane with 110 mph winds, in the 24 hours ending at 8 a.m. EDT Saturday. The National Hurricane Center predicted little change in Elsa’s strength through Saturday.

Figure 4. Track forecasts out to eight days for Elsa from the 6Z (2 a.m. EDT) Friday, July 2, 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 Elsa. The guidance has shifted more to the west than was the case 24 hours earlier, and it predicts a greater threat to western Cuba and the U.S. Gulf Coast than before. But there was high uncertainty on the future track of Elsa beyond Monday morning (72 hours). (Image credit: Tropical Tidbits)

As Elsa approaches southwestern Haiti, Jamaica, and eastern Cuba on Saturday night, the storm’s forward speed will slow to about 20 mph, which may aid Elsa’s intensification by allowing the storm to get more vertically aligned. However, the storm will begin interacting with the high terrain of Hispaniola at this time, which will likely inhibit development. At some point, Elsa is likely to cross over one or more of the mountainous islands of Hispaniola, Jamaica, or Cuba, which is likely to significantly disrupt the storm. Southern portions of Haiti and the Dominican Republic are likely to receive dangerous flooding rains of 4-8 inches Saturday through Sunday, and these heavy rains will spread into Jamaica and eastern Cuba beginning on Saturday evening.

On Monday, a trough of low pressure passing to the north of Elsa is expected to turn the storm to the north, resulting in landfall on the U.S. Gulf Coast, most likely in Florida. The magnitude of the threat to the U.S. is difficult to assess until it is apparent how much interaction Elsa will have with the high mountains of Hispaniola, Cuba, and Jamaica.

Bob Henson contributed to this post.

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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...