Gonzalo a hurricane risk to Caribbean (maybe US), Hanna a rainfall risk to Texas

Two tropical storms, Gonzalo and Hanna, each of which has broken records as the earliest seventh and eighth named storms to form of the Atlantic tropical storm and hurricane season, are threatening impacts in the coming days.

The 2020 Atlantic hurricane season is following true to forecasts for a very active season in terms of number of storms, as it is currently running ahead of records.

Of course, these forecasts for high levels of activity do not necessarily mean high levels of insurance and reinsurance market losses, as it is landfalls that matter, in highly urbanised locations by strong storms and hurricanes.

Update, Saturday 25th July, 09:00 BST:

Tropical storm Gonzalo has defied the forecasts and weakened considerably, now expected to dissipate as it passes the Windward islands.

Meanwhile, tropical storm Hanna has intensified more than expected and could reach hurricane status before making landfall later today on the southern Texas coastline. We’ve published a new update on hurricane Hanna here.

Tropical storm Gonzalo is forecast to become hurricane Gonzalo in the coming day or so, as it tracks towards the southern Caribbean windward islands.

Gonzalo was the earliest seventh named storm of a tropical season and is now heading for the Caribbean with sustained winds of over 60mph and higher gusts.

Expected to reach hurricane status, Gonzalo could then weaken slightly and head into the eastern Caribbean Sea, before then regaining strength on its passage northwest.

Gonzalo is a relatively small tropical storm, with tropical-storm-force winds only extending outward up to 25 miles from the centre, which should save some islands from as strong a hit as it passes.

Once through the Caribbean Gonzalo could enter the Gulf of Mexico and while there is significant uncertainty in precisely where the storm will track to, a U.S. Gulf Coast landfall is in the forecast for certain model runs.

The below is taken from TropicalTidbits.com and shows a GFS model run for storm Gonzalo.

At the moment tropical storm Gonzalo’s intensity remains uncertain as well, as it has so far to track across the Caribbean and Gulf before it would come close to the United States.

Forecast model intensity outputs from TropicalTidbits.com can be seen below.

Other models show a weak hurricane Gonzalo tracking into Mexico, some show it recurving and others show a relatively strong hurricane landfall in the United States, making this a storm in need of monitoring for the insurance, reinsurance and insurance-linked securities (ILS) communities.

Tropical storm Hanna has also now formed, becoming the earliest eighth named storm of the Atlantic season on record.

Tropical storm Hanna is destined to make landfall in the United States, as it is tracking across the Gulf of Mexico towards southern Texas.

Tropical storm Hanna is currently packing 40mph sustained winds with higher gusts. Strengthening is expected until Hanna makes landfall on Saturday, so there is a chance Hanna could reach low hurricane strength by landfall, although at this time it seems a stronger tropical storm landfall is the more likely scenario.

The modelled intensity forecast from TropicalTidbits.com shows the spike in wind speeds expected prior to landfall.

However, storm Hanna’s main threat to the southern Texas region is likely to be rainfall totals, with isolated amounts of 12 inches or more forecast as the storm tracks ashore.

More widely, 3 to 8 inches of rain is expected across a wide swathe of the western Gulf Coast region.

Hanna is unlikely to pose much of a threat, in terms of insurance or reinsurance market losses it seems.

Gonzalo meanwhile will pose a threat of damage and loss of life to the Caribbean islands it passes close to, but it’s potential for insurance and reinsurance market losses is less certain at this time.

It will all come down to the route Gonzalo takes across the Caribbean Sea and into the Gulf of Mexico, if it makes it that far. With the U.S. in its sights currently, according to some model runs, there is a possibility of Gonzalo maintaining hurricane strength over the warm waters it will travel across and that means all eyes will be on the tropics over the coming days.