The center has already been watching an area over the North Atlantic, east of Bermuda. Meteorologists have designated this area with the name Invest 90L, which indicates a particular area of disturbed weather that is being monitored by the NHC. This storm system has a high chance of developing on Friday or Saturday.
On Thursday evening, the NHC added a different area in the Gulf of Mexico. This area of stormy weather currently has a medium chance at becoming a tropical depression or a named, tropical storm before tracking into the Deep South on Saturday.
If these storms form, they will have originated in parts of the Atlantic or Gulf of Mexico that have never had a tropical cyclone develop in May. Typically, storms during this month form over the eastern Gulf of Mexico, western Caribbean Sea and near the southeastern US coast.
As of Friday afternoon, the NHC gives Invest 90L a 90% chance of forming into a subtropical storm within the next 48 hours near Bermuda. The center says the storm could be named later on Friday if thunderstorm activity increases. Invest is short for investigation.
A subtropical storm has similar characteristics of a tropical storm but is not considered fully tropical because it doesn’t depend on warm water temperatures to fuel its development.
If winds reach at least 39 mph, then the storm will be named “Ana.”
This would make it the seventh season in a row with a named storm forming before the official June 1 start date of hurricane season in the Atlantic basin.
Out of the past six years (2015-2020), there have been eight preseason named storms, four of which made landfall in the US, including Ana in 2015.
Even if this storm doesn’t get named, gusty rain showers are expected in Bermuda from Friday to Sunday before the storm races east and away from any land by early next week.
Monitoring the Gulf of Mexico for development, too
There is an area of thunderstorms located over the western Gulf of Mexico that the NHC is also monitoring for tropical cyclone development.
The center gives this area to watch a 60% chance of tropical cyclone formation by Saturday. Whether or not this system remains disorganized, or becomes a tropical depression or a tropical storm, it will move north and over Texas and Louisiana this weekend and into early next week.
“The associated shower and thunderstorm activity remains limited, but any increase in this activity may result in the formation of a short-lived tropical depression or storm before the system moves inland over the northwestern Gulf coast tonight, and potential tropical cyclone advisories may be needed as early as this afternoon,” the National Hurricane Center said.
The concern for flash flooding will thus remain in place, with flash flood watches in effect for over five million people from the coast through southeastern Oklahoma and southwestern Arkansas.
“Soils are saturated and many rivers in flood or rising across western Louisiana. As such, this additional rainfall could worsen flooding or easily initiate new flash flooding,” the Weather Prediction Center said.
Coastal flood advisories are also in effect for portions of Texas, Louisiana and Mississippi for Friday and possibly Saturday. Water levels may rise 1 to 2 feet higher than normal high tide levels.