Review of June Tropical Cyclone Activity in the Atlantic

Since the official start of the Atlantic hurricane season, June 1, two tropical storms have formed and impacted land areas. In June, the area with the greatest risk of tropical development is the Gulf of Mexico, Bay of Campeche and western Caribbean.

Origins and Tracks of June Tropical Cyclones

Contradicting climatology, Tropical Storm Bret formed 108nm East of Trinidad on June 19th. This area is typically unfavorable in June due to the amount of dry air and wind shear in the region. Bret was the earliest storm to form this far south in the Atlantic since official records began in 1851.

Bret originated as a rather unimpressive African wave, which progressed westward across the Atlantic in a marginally favorable tropical environment. A weak tropical wave to its west moistened the atmosphere over the eastern Caribbean, assisting in making conditions more favorable for Bret to develop. Here is a look at the moisture content over the tropical Atlantic in the days leading up to Bret’s formation:

noaa-goes-wv-animated-june15-16

While Bret was causing alarm in Trinidad in northern South America, Tropical Storm Cindy began to develop over the northern Gulf of Mexico. Cindy originated as an area of disturbed weather over the western Caribbean and Central America, and became Invest 93L East of the Yucatan Peninsula on June 17th.

This broad, disorganized low became difficult to track over the next five days. The ECMWF model maintained a forecast for landfall over Mexico or southern Texas. On the other hand, the GFS model favored a landfall near the Florida Panhandle. The discrepancy between the global model tracks continued through landfall on June 22. Higher resolution, regional forecast models eventually offered a more accurate middle-ground solution near the upper-Texas coast.     

NAM Wind Forecast for Cindy valid 00z June 21, 2017

Weak steering flow in the region contributed to the poor model performances. Another complexity was the close proximity to an upper level low over the northwest Gulf of Mexico. This feature provided high wind shear, resulting in a disorganized and asymmetrical storm. As a result, Cindy appeared to be subtropical rather than purely tropical through its duration. Southwesterly upper level winds from the trough pulled dry air into Cindy, restricting deep convection to the East side of the storm. Cindy’s battle with dry air on June 20th is seen in the brown coloring in the NOAA water vapor animation below.

WV Cindy Tues

High pressure from the western U.S. eventually built eastward over Texas, forcing Cindy to move northward. Air Force Reserve reconnaissance aircraft and a nearby ship confirmed a maximum intensity of 50kts the evening of June 20. Despite being a weak tropical storm, Cindy produced a large area of gale force winds and storm force gusts across the northern Gulf of Mexico. Cindy weakened to 40kts before making landfall near Sabine Pass, Texas on June 22nd.

NASA IMERG Data Cindy 2017
Cindy Estimated Total Rainfall from NASA

Both storms were short-lived with the primary threats of heavy rainfall and flash flooding. The Trinidad & Tobago Meteorological Service forecast 2-6 inches of rain for Trinidad and Tobago, Grenada and its Dependencies during the passage of Bret. NASA’s Integrated Multi-satelliE Retrievals for GPM (IMERG) data estimated rainfall totals over the eastern Gulf of Mexico and southeastern U.S. for the duration of Cindy. Notably, rainfall in excess of 10 inches occurred well east of Cindy’s center over the northeastern Gulf of Mexico and along the Gulf coast from southeastern Louisiana to the western Florida Panhandle.

The peak of the Atlantic hurricane season is still to come, so it’s important to remain vigilant for any approaching tropical storm. Whether you are concerned with a tropical storm tracking toward the eastern Caribbean, or a major hurricane developing in the Gulf of Mexico, our meteorologists are available 24/7 to keep you ahead of the storm.

Contact us to learn more about our online and mobile interactive tracking tools.

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