Tropical Storms Laura and Marco headed into Gulf, will threaten US next week

Atlantic tropical activity ramped up again this week, with Tropical Storm Laura forming east of the Northern Leeward Islands and Tropical Storm Marco forming in the Western Caribbean. Both systems are expected to enter the Gulf of Mexico in the coming days, and threaten the United States next week.

The uptick in Atlantic tropical activity was well forecast. A developing MJO wave and a CCKW propagating from the Pacific to the Atlantic gave meteorologists almost three weeks of warning. Now that tropical storms have developed, the uncertainty resides in where the systems will track and how they will behave as they do so.

Tropical Storm Laura

Tropical Storm Laura is currently 70 miles northwest of Port Au Prince, Haiti. It has maximum sustained winds at 50mph and is moving to the west-northwest at 21 mph. Tropical Storm Warnings are remain in effect for Cuba, Haiti, the Dominican Republic, the Southeast Bahamas and the Turks and Caicos Islands.

Laura has maintained it’s intensity so far, despite moving over Hispaniola. Favorable atmospheric condtions and orographic enhancement from the mountains of Hispaniola, has resulted in more intense-banding of convection just south and east of the low-level center. Laura’s track has shift slightly further south, closer to the southern coastlines of Haiti and Cuba. Thus Laura is more likely to maintain it’s intensity until it emerges into the Gulf of Mexico by Monday night or Tuesday.

Laura is currently forecast by NHC to track further south over the Hispaniola and Cuba coastline with little strengthening expected through Monday. It will then emerge over the Gulf of Mexico, where it could strengthen into a major hurricane before impacting the Texas and Louisiana coasts by Wednesday and Thursday.

There is some concern for rapid strengthening of Laura once it arrives in the Gulf of Mexico. If the storm does emerge into the Gulf of Mexico next week, the environment which it encounters could be characterized by very low shear and very warm waters – rocket fuel for tropical systems.

Interests along the Gulf of Mexico coastline should carefully watch the evolution of Laura in the coming days.

Tropical Storm Marco

Tropical Storm Marco is currently located in the South-Central Gulf of Mexico. It has maximum sustained winds at 70mph and is moving to the north-northwest at 12mph. Hurricane Warnings are now in effect for much of Southeast Louisiana. Marco is expected to become a minimal hurricane later today and impact Southeast Louisiana and Mississippi coasts on Monday.

As with Laura, there is uncertainty as to how Marco will behave once it enters the Gulf. The storm is generally expected to turn westward as a result of an upper level ridge, and may encounter more wind shear as a result. The official NHC forecast actually calls for the system to weaken back to tropical storm strength as a result. But when this happens is uncertain. Marco is small tropical cyclone, which can fluctuate in intensity quickly. Thus hurricane-force winds could still reach the coastline.

Uncertainty abound with both systems in Gulf

Both tropical systems are on a path towards the Gulf of Mexico over the next few days. This creates a tremendous amount of uncertainty, and forecast model guidance is struggling greatly to discern how each system will behave.

With both systems in the Gulf of Mexico, the tropical systems will almost certainly influence one another in some way. If they are close enough, it is possible that one tropical cyclone could grow stronger, negatively impacting the other – and vice versa.

The strengthening or weakening of individual storms can also cause changes to the systems tracks and steering currents – commonly referred to as the Fuijiwhara effect, which is the binary interaction that can cause tropical systems to circle around each other or even merge. However, with Marco now expected to make landfall on Monday and Laura tracking further south and west over the Gulf of Mexico, chances of this interaction occurring have decreased.

There is a lot to consider with these possible interactions, and its worth noting that the tracks of the systems could change dramatically from the current forecast. If you live along the Gulf Coast of the United States, now is the time to prepare in advance. Do not focus on the exact forecast tracks of the systems at this time. Instead, make preparations in advance for a tropical system and adjust accordingly as the event draws closer.