9:10 AM (Sunday) | ***Double-strike of tropical storms on the central/western Gulf of Mexico***

The latest IR satellite image features Tropical Marco (Gulf of Mexico) and Tropical Storm Laura in the northern Caribbean. Image courtesy NOAA, tropicaltidbits.com

Overview

The very active 2020 Atlantic Basin tropical season continues and there is likely to a “double-strike” of tropical storms on the central/eastern Gulf of Mexico by the middle of the week.  Tropical Storm Marco is now out over the open waters of the very warm Gulf of Mexico and is likely headed towards a landfall on Monday in the central Gulf region (Louisiana).  Tropical Storm Marco is now flirting with hurricane status and its trek over the very warm water of the Gulf could give it the boost needed to attain category one hurricane status.  Tropical Storm Laura is currently interacting with the island of Hispaniola and it too is likely to make a run towards the central Gulf region (Louisiana/Texas border region) by the middle of the week.  Tropical Storm Laura may also get a boost from the very warm waters of the Gulf of Mexico which could boost it to hurricane status before landfall later in the week. 

The Gulf of Mexico currently features some of the warmest water in the world and this will aid in the intensification of Marco and Laura. Map courtesy NOAA, tropicaltidbits.com

A key factor in intensification prospects: sea surface temperatures

Sea surface temperatures are crucial in both the formation and intensification of tropical cyclones in the Atlantic Basin and they tend to reach their peak during the latter part of August or the first half of September.  Typically, tropical activity ramps up during the latter stages of August and reaches a peak in mid-September and this is largely due to the correlation with the annual rise in sea surface temperatures. In fact, about 2/3rds of all Atlantic Basin hurricane activity occurs between August 20th and October 10th.  Current sea surface temperatures are plenty sufficient in the tropical Atlantic to support the generation and intensification of tropical cyclones with much of the Gulf of Mexico experiencing > 30° C - some of the warmest water anywhere around the world.

The predicted storm tracks of Marco (left) and Laura (right) by the 00Z run of the Euro ensembles. Maps courtesy ECMWF, weathernerds.org

Current tropical activity

Tropical Storm Marco

Tropical Storm Marco is a rather compact storm now situated over the open Gulf of Mexico with maximum sustained winds of 70 mph and movement towards the NNW at 13 mph.  While it wouldn’t take much of a boost in strength for Tropical Storm Marco to attain hurricane status, the intensity forecast remains somewhat tricky due to its rather small size and competing environmental conditions.  It is moving over some of the very warmest water anywhere around the world at this time which could give it the boost needed for reaching hurricane status, but there also is some wind shear in its vicinity.  In fact, some models suggest there will be quite an increase in wind shear as this tropical system approaches or reaches southern Louisiana on Monday and this could result in a rather quick weakening of the storm once it does arrive.  Nonetheless, residents along the central Gulf coast should continue with preparations today and expect a possible hurricane landfall later tomorrow.

Tropical Storm Laura

Tropical Storm Laura has maintained an impressive convective pattern as its center interacts with the southern part of the Dominican Republic on the island of Hispaniola.  Hispaniola often results in some weakening of a tropical system as its rugged terrain can disrupt the overall circulation pattern.  In an ominous sign, Tropical Storm Laura is holding its own and its outflow pattern has actually improved in all quadrants.  This is suggestive that its long-term prospects are quite good in terms of hurricane-level storm intensity. Tropical Storm Laura is moving WNW at 18 mph with maximum sustained winds of 45 mph and its next pass over will be of the island of Cuba before it pushes into the Gulf of Mexico.

After exiting Cuba and moving out over the open and very warm waters of the Gulf of Mexico, intensification could very well result in the attainment of hurricane status as it likely heads on a path towards the central Gulf coast (Texas/Louisiana border region).  This system is likely to make landfall by the middle of the week and its story may not be over at that time.  There are signs that the remains of Tropical Storm Laura will push northward through the south-central states and it ultimately could have an impact on the Mid-Atlantic region by late in the week or during next weekend.

Surface weather map from September 1933 which featured two tropical systems in the Gulf at the same time…one impacted Texas and the other Florida. Credit Philip Klotzbach (Colorado State University), Twitter.

Final notes

The most Atlantic Basin named storms to make landfall in the continental US (CONUS) by the end of August is six which happened in 1886 and 1916. This year the CONUS has already had five landfalling named systems: Bertha, Cristobal, Fay, Hanna and Isaias. While only two of the landfalling systems this year have been at hurricane strength (Hanna, Isaias), five of the six named storms that made landfall by the end of August in 1886 did so at hurricane strength, including the especially devastating Category 4 “Indianola” hurricane which was one of the most intense ever to strike the US. (Credit for this info to Philip Klotzbach of Colorado State University). One other note, while it is rare for there to be two tropical storms in the Gulf of Mexico at the same time, it is not unprecedented.  In 1933 for example, one hurricane had an impact on Texas while another impacted Florida at nearly the same time. In fact, the two landfalling hurricanes in 1933 hold the record for the shortest time between hits in the continental US which was 23 hours (Treasure Coast region of Florida and Brownsville, Texas).

Buckle up…the rest of August and at least the first part of September will be a very active period in the tropical Atlantic Basin.

Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com

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