For almost a week, we have been watching a cluster of showers and thunderstorms in the Caribbean for signs it might develop into something more menacing. Now it seems that is likely within the next five days as it tracks north over the Yucatán Peninsula into the Gulf of Mexico. When it arrives, forecast models suggest it will spin up into at least a tropical depression and maybe even the hurricane season’s first named tropical storm.
At the very least, several inches of torrential rain are likely across the Gulf states east of Texas.
On Thursday morning, the National Hurricane Center gave the seemingly-disorganized cluster of thunderstorms a 40 percent chance of developing in the next 48 hours and an 80 percent chance in the next five days.
Forecast models like the ECMWF and the GFS predict the system will be approaching the northern Gulf Coast by Sunday. So far, none of the models suggest it will strengthen into a hurricane. The main threat from this system continues to be its heavy, flooding rain.
Even if the storm does not develop, the circulation is going to pull moisture out of the Gulf of Mexico and toward the southeast. More than 6 inches of rain are in the forecast for parts of the Gulf Coast. The heaviest rain will probably stretch across Florida, Alabama and Georgia.
Widespread #heavy_rain will likely move across Florida, the Southeast and westward to the central Gulf coast as a low pressure system is forecast to develop over the Gulf of Mexico during the Memorial Day weekend. https://t.co/v8QovElKmf pic.twitter.com/J2OEkfwYKC
— NWS WPC (@NWSWPC) May 24, 2018
There are a few notable factors that would limit the development of this system in the Gulf. The sea surface temperature is not actually that warm right now. It is only around 80 degrees, which is generally considered the lower limit for these things to form — it does not make it impossible, but it is not that favorable.
Volatile upper-level winds are also preventing this system from developing into something stronger. However, models expect this will subside a little by Saturday and Sunday, leaving a window for the system to form in the Gulf.
Even though June 1 is generally the start of hurricane season, early storms are not uncommon. In fact, as I wrote this week, it seems as if hurricane season is starting earlier each year. In 2017, the first storm formed April 19. In 2016, the first storm formed in January and managed to reach hurricane status. Tropical Storm Bonnie followed in late May. In 2015, Tropical Storm Ana formed in early May.