Atlantic Hurricane Season

Will Tropical Storm Elsa be the first Atlantic Hurricane in 2021?

01 Jul 1150Z Nesdis image courtesy NOAA

During what has already proven to be a fairly active early season for tropical activity in the Atlantic, Tropical Storm Elsa has become the fifth system of the year and the first to affect the Caribbean Sea.  Elsa has been named as of July 1st, making it the earliest named 5th storm for the North Atlantic basin on record, even beating Edouard on July 06th last year’s record setting season.

The National Hurricane Center (NHC) began issuing warnings for the system late Wednesday afternoon, as then Potential Tropical Cyclone Five started to become better organized.  The conditions that allowed the system to develop were warm sea surface temperatures and decreasing vertical wind shear. At the time of NHC’s first advisory, the system’s eastern semi-circle was being impacted by a pocket of adverse upper-level westerly shear (20-25kts) which inhibited convection in that region.  A few hours later, the system moved west into a lower shear environment which allowed the already warm sea surface temperatures (27-28C) to fuel more sustained thunderstorms to the east. The NHC subsequently upgraded the system to Tropical Depression Five with their second advisory as of July 01/0300Z, so becoming the fifth system of the season. 

Above Image courtesy of the National Hurricane Center

Under the influence of a strong subtropical ridge to the north, newly upgraded Tropical Storm Elsa is currently moving westward at 22kts with maximum sustained winds of 35kts and gusts to 45kts.

Intensity – first hurricane of the year?

This latest development poses some important questions. How strong is Elsa expected to become and who will be affected? Taking a look at the above graphic from NHC, we can generally infer that Elsa is expected to maintain its status as a tropical storm, with near-term impacts to the Lesser Antilles and potentially northern Leeward Islands.

While some models are hinting at TS Elsa becoming a hurricane, the probability of this occurring remains relatively low for now. If we examine the below intensity analysis, we can see most models agreeing on the system remaining a tropical storm, which coincides with NHC’s latest forecast. Although frictional effects from Elsa’s rapid forward speed and the system’s potential to interact with multiple land masses will act to curtail rapid intensification, it is still early to completely rule out the several category 1 outliers in the below analysis. 

Tropical Storm Elsa – Model Intensity courtesy of tropicaltidbits.com

Who will be impacted by Tropical Depression Five?

The NHC has issued Tropical Storm Warnings for the Lesser Antilles and Tropical Storm Watches for the northern Leeward islands. Looking at the latest ensemble track guidance in the image below, we see the European and GFS are in good agreement through the first 48-60hrs before diverging. It should be noted that the GFS is the stronger of the two models with a couple ensemble members strengthening the system to a Category 1 hurricane just prior to landfall near Barbados and more members trending stronger once the system encounters the warm waters of the Caribbean.

ECWMF and GFS Ensembles Image courtesy of weathernerds.org 

Given the potentiality of Elsa affecting multiple land masses, interests in the above areas mentioned should pay close attention to subsequent forecasts and advisories, especially given the system’s fast forward movement. 

Lastly, Elsa will likely have a large impact on shipping, with the system’s expected track crossing several choke points for ships entering/exiting the Caribbean Sea from the Western Atlantic and Gulf of Mexico. This could lead to an increase of en-route alterations, transit delays, or delays in departure for vessels at or near affected ports. More particularly, ships transiting through Old Bahama Channel should pay close attention as well. 

Stay connected and safe.

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