Hurricane Elsa, first Atlantic hurricane of 2021, rumbles across the Lesser Antilles » Yale Climate Connections

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The first Atlantic hurricane of the year, Hurricane Elsa, hit the Lesser Antilles in the Caribbean on Friday morning. Elsa intensified into a Category 1 storm with winds of 75 mph as it passed south of Barbados at 7:15 a.m. EDT Friday. Elsa’s winds increased 35 mph in the 24 hours ending at 8 a.m. EDT Friday met the National Hurricane Center’s minimum definition of rapid intensification.

The Barbados Meteorological Service reported continuing winds of 74 mph, gusting to 86 mph, near 7:30 a.m. EDT as Elsa’s northern eye passed over the southern part of the island. Barbados Airport reported strong winds of 63 mph, gusting to 86 mph, at 7:18 a.m. EDT. Elsa brought torrential rain to the island; The highest amount of rainfall from the personal weather station Weather Underground network in Barbados was 4.68 inches as of 11 a.m. EDT.

At 2 p.m. EDT on Friday, Elsa was centered 95 miles west-northwest of St. Vincent Island, accelerating from west to northwest at 29 mph across the eastern Caribbean. Hurricane Hunters found that Elsa was continuing to condense, with a maximum wind speed of 85 mph and a central pressure of 991 mb.

Elsa has gained some latitude since Thursday, and was set at 13.7 degrees north latitude. This location far from the equator will aid development, as will warm sea surface temperatures near 28 °C (82 °F), moderate wind shear of 10 to 20 knots, and humid weather with an average level relative humidity of 65% (although That water vapor satellite imagery showed dry air on the northwest side of the storm being wrapped in Elsa’s rotation.) The main factor holding back development until Saturday will be Elsa’s fast forward speed, which will make it difficult for the Storm to stay upright.

Wind and flood damage is a concern of Elsa in the Lesser Antilles. Elsa’s heavy rain is of particular concern on Saint Vincent Island, where ash from a series of April 9-22 eruptions from Soufriere volcano is likely to collect in dangerous mudflows. Radar-estimated precipitation amounts over the island from Barbados’ radar were 1-4 inches as of 2 p.m. EDT Friday.

Because of Elsa’s rapid advance, Tropical Storm force winds were mostly confined to the north 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 on July 2, 2021, as the cyclone’s northern eyewall was impacting Barbados. (Photo credit: Barbados Weather Service) An unusually early Caribbean cyclone

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

#Elsa became the first hurricane of the season on July 2, the first hurricane since 2012. This graph shows the formation dates of the first hurricane over the past 50 years (1972-2021) as well as the trend. (I’m not including Alex on purpose in January 2016 here) pic.twitter.com/xVxKKla9VT

Brian McNoldy (@BMcNoldy) Jul 2, 2021 Herald of an active hurricane season?

Of concern is that Elsa formed early in the season in the main cyclone development zone (MDR) (between the coasts of Africa and Central America, including the Caribbean). Typically a tropical cyclone (the general term for all cyclones, tropical storms, and tropical depressions) that forms in this region early in the season is a harbinger of an active peak portion of the season, showing that the atmosphere and oceans lead to activity. In the comments from our previous article, NCHurricane2009 provided a detailed analysis of this, examining the last 13 seasons in the Atlantic where the MDR tropical cyclone developed in June or July. Of these thirteen seasons, 10 were active, and only three could be described as inactive. 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: Brit 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 two hurricanes, and there are no major hurricanes); – 2008: Bertha formed in July (16 specific storms, 8 hurricanes, 5 major hurricanes; Dolly, Gustav, Ike, Omar and Paloma were high impact hurricanes); – 2005: Dennis and 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, George and Mitch were high impact hurricanes); – 1997: TD5 formed in July (9 named storms); And – 1996: Bertha and Caesar formed in July (13 named storms; Fran and Hortense were hurricanes of great impact).

Figure 2. Trajectories of all hurricanes observed in the Caribbean in March and July from 1851 to 2020. A total of 20 hurricanes were observed at the beginning of the season. (Image credit: NOAA)

The tropics are usually 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 Ocean—an average of one storm every 1.5 years, and one every two years. and a major hurricane every 14 years (thanks to Tony Bright for those stats). Since 1851, a total of 20 hurricanes have been observed in the Caribbean in March and July – only about one every eight years (Fig. 2).

Figure 3. Projected wind speed (colors) and sea level pressure (black lines) for Tropical Storm Elsa at 8 a.m. EDT (12 Z) Sunday, July 4, starting at 12Z on Friday, July 2, HWRF model run. The model predicted Elsa would affect Haiti, Jamaica, and Cuba as a low-level 3 hurricane with winds of 115 mph and a central pressure of 969 mb. This predicted intensity is close to the maximum of what intensity prediction models predict. (Image credit: Tropical Tales) Elsa’s Predictions

As it advances from west to northwest at 20-30 mph from Friday to Saturday, Elsa will remain mostly dry air south of the desert air layer, although water vapor images have shown that some of the dry air on the northwest side of Elsa can that interferes with development. Conditions will be favorable for development, according to Friday’s 12Z track of the SHIPS model, with moderate wind shear of 10 to 20 knots and steadily rising sea surface temperatures. Elsa’s development will also be favored by an extensive region of rising air over the Atlantic, due to Friday’s passage of an atmospheric turbulence called the Kelvin Double Wave, as explained in a tweet by Eric Webb.

However, Elsa’s forward speed is likely to prevent development, as fast-moving storms have trouble keeping their core vertically aligned. The 12Z Friday run of SHIPS gave a 28% chance that Elsa would intensify at 35 mph into a developing Category 2 hurricane with winds of 110 mph, in a 24 hour period ending at 8 a.m. EDT Saturday. The National Hurricane Center expected little change in Elsa’s strength through Saturday.

Figure 4. Tracking the eight-day forecast for Elsa from 6Z (2AM EDT) on Friday, July 2, GFS (GEFS) ensemble model run. The black line is the average of 31 members of the group; The predictions of individual group members are the thin lines, color coded by the central pressure they expect for Elsa. Guidance has shifted further west than it was 24 hours ago, anticipating a greater threat to western Cuba and the US Gulf Coast than before. But there was a great deal of uncertainty about Elsa’s future trajectory after Monday morning (72 hours). (Image credit: Tropical Tales)

As Elsa approaches southwest Haiti, Jamaica and eastern Cuba Saturday night, the storm’s forward speed will slow to about 20 mph, which may help intensify Elsa by allowing the storm to align vertically. However, the storm will begin to interact with the higher terrain of Hispaniola at this time, which will likely hamper development. At some point, Elsa will likely cross one or more mountainous islands in Hispaniola, Jamaica or Cuba, which will likely disrupt the storm significantly. Southern parts of Haiti and the Dominican Republic are likely to experience 4 to 8 inches of severe flooding rain from Saturday through Sunday, and this heavy rain will spread to Jamaica and eastern Cuba starting Saturday evening.

On Monday, a drop in low pressure north of Elsa is expected to shift the storm north, making landfall on the US Gulf Coast, most likely in Florida. It is difficult to assess the extent of the threat facing the United States until it is clear how much Elsa interacts with the high mountains of Hispaniola, Cuba and Jamaica.

Bob Henson contributed to this post.

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