Tropical Thursdays, July 18th, 2019

Weather Headlines

Chief Meteorologist Noel Rehm and Dr. Athena Masson discuss activity in the tropics. Hurricane Barry made an official landfall along Marsh Island and Intracoastal City, Louisiana during the early morning hours on June 13. It briefly reached Category 1 status on the Saffir-Simpson Hurricane Wind Scale with winds of 75 mph before quickly weakening back to a Tropical Storm as it pushed inland.

Louisiana was sparred thanks to dry air wrapping into the system and the majority of the precipitation remaining offshore as Barry moved inland. 14 inches of rain was reported in Lake Charles and leeves across the state were overtopped. Terrebonne and Plaquemines parishes experienced heavy flooding which required some emergency evacuations during the height of the storm.

Arkansas saw an unconfirmed maximum rain value of 16.17 inches making Hurricane Barry the wettest tropical system to impact the state of Arkansas. The previous record was 13.91 inches of rain set back in 1989 from Tropical Storm Allison.

Barry has since transitioned into an extratropical cyclone and is moving through the northeast and parts of Canada delivering heavy rain and flash flooding across the province of Ontario. Meanwhile the Atlantic and Gulf of Mexico remains quiet. A few systems could spawn off the west coast of Africa in the next week but so far the National Hurricane Center does not see any potential for a developing tropical system over the next five days.

Wind shear values in the North Atlantic and Gulf of Mexico. Areas marked with an (*) are favorable for tropical cyclone development.

Wind shear is one of the main ingredients that contributes to tropical cyclone formation. The less wind shear, the better chance for a storm to develop. Prime areas for development this week include central parts of the Gulf of Mexico, north of Bermuda, and east of the Turks and Caicos. Water temperatures are also a prime ingredient for tropical cyclone formation. Many locations across the North Atlantic and Gulf of Mexico are recording sea surface temperature values in the mid to high 80’s. The only ingredient missing at this time is a well developed disturbance over these areas.

Current sea surface temperatures in the Gulf of Mexico, Caribbean, and western Atlantic

Typically for the month of July we start to see our first named system form in the North Atlantic. Most of the time we see the Gulf of Mexico to be the primary breeding ground for these tropical systems due to the warm sea surface temperatures. We generally see an increase in activity in the western Caribbean sea, which on occasion pushes these disturbances into the Gulf of Mexico. The month of July is also when we could see some formation out in the open Atlantic, usually off the east coast of Florida where the warm Gulf Stream helps to fuel these systems. Finally, the tropical Atlantic, to the east of the Lesser Antilles, could produce a tropical cyclone.

Typical breeding grounds for Tropical Cyclones during the month of July

We are about two weeks away from August and this is generally when we see our first active month of Hurricane Season as well as the first major hurricane form (Category 3-5). August is generally the same as the month of July with the Gulf of Mexico and western Caribbean seeing activity. However, the Atlantic begins to become more favorable for tropical development as wind shear lessens and sea surface temperatures continue to rise. Systems will begin to come off of Africa and have ample time to strengthen in the open Atlantic, growing sometimes to major hurricanes before reaching the shores of North America, Central America, and the Caribbean Islands.

Typical breeding grounds for Tropical Cyclones during the month of August

The Atlantic remains quiet but we are watching two disturbances in the eastern Pacific that have a fairly good chance of strengthening and becoming Tropical Storms. The one furthest from shore is showing less organization due to its location in a strong wind shear environment. The National Hurricane Center is giving this one a 40% chance of becoming a named system within the next 5 days. Following right behind is a second disturbance area which looks to be more healthy and in a more favorable environment. The National Hurricane Center is giving it a 50% chance of development over the next several days.

Areas of potential development in the East Pacific

Hurricane Season officially ends November 30th. There is plenty of more time for tropical systems to form and impact land. This is only the tip of the iceberg as we get ready to enter into the active months of the season, August, September and October. Join us next week for another Tropical Thursdays.

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