01:38 - Source: CNN
How are hurricanes named?

Story highlights

Alberto formed Friday as a subtropical storm

Heavy rain and flooding are the biggest threats, with dangerous surf conditions possible

Tropical storm watches issued for portions of the Gulf Coast

CNN —  

Sorry to rain on your beach barbecue: There is a 90% chance of tropical development in the Gulf of Mexico over Memorial Day weekend and an even better chance of soaking rains across the eastern Gulf Coast.

Although hurricane season doesn’t begin until June 1, a tropical system off the Yucatan Peninsula has become Subtropical Storm Alberto as of 11 a.m. Friday, according to the National Hurricane Center.

Click here to track the storm

For holiday beachgoers flocking to the US Gulf Coast looking for their first taste of summer sun, Alberto is making the forecast look pretty grim.

Subtropical storms are low pressure centers that have characteristics of both tropical storms (which have warm cores and get their energy from warm ocean water) and more traditional storm systems (which have cold cores that get their energy from clashes of warm and cold air) that occur in the midlatitudes with cold and warm fronts.

The threats associated with subtropical and tropical storms are largely the same: heavy rainfall, gusty winds and rough surf.

Given that Alberto has a couple of days to traverse warm waters in the Gulf of Mexico, it could become fully tropical.

Forecast models, which were showing very different possible scenarios earlier in the week, are now in agreement in bringing the storm north into the Gulf Coast by the latter half of the three-day weekend.

A hurricane hunter aircraft is scheduled to fly through the system Friday to provide more information on the structure, according to the National Hurricane Center.

What to expect with Alberto

The National Hurricane Center issued a tropical storm watch, which means tropical storm conditions are possible within the watch area within 48 hours, from Indian Pass, Florida, westward to Grand Isle, Louisiana, including Lake Pontchartrain, Lake Maurepas and metropolitan New Orleans.

Conditions along the coast from Florida to Louisiana will begin to deteriorate on Saturday afternoon as the system builds over the central Gulf.

Things will worsen on Sunday as the rain becomes heavier and more frequent and is accompanied by stronger winds of 40 miles per hour or more.

In addition to the tropical-storm-force winds and storm surge along the coastline, beachgoers who brave the conditions will also need to be on high alert for rip currents.

The American forecast model has been very wishy-washy on the location. Most of its runs showed the storm moving across the Florida peninsula. Thursday’s shift aligns it more with a track similar to the European model, which has been a little more consistent, showing a tropical or subtropical storm drifting ashore near New Orleans.

Alberto is likely to make landfall Monday between New Orleans and Destin, Florida, before moving into Mississippi and Alabama by Tuesday.

No matter where this storm moves or how strong it becomes, it will continue to bring tropical moisture into the South from Louisiana to North Carolina. The heaviest rain will fall near the Gulf, with Florida, Georgia, Louisiana, Mississippi and Alabama seeing seven-day rainfall totals of 4 to 7 inches.

Flash flood watches are posted for portions of Florida, Alabama, Mississippi and Georgia, extending to Atlanta, with rainfall totals expected between 3 and 5 inches through Tuesday.

Early storms

As we have seen in years past, environmental conditions sometimes allow for development before the hurricane season begins. The last time a tropical cyclone was named Alberto was in 2012; it also formed before the season began, on May 19. It became a tropical storm that meandered off the cast coast of Georgia and South Carolina.

Just last year, we had a named storm – Tropical Storm Arlene – east of Bermuda in April.

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This early development doesn’t necessarily mean we are in for a busy hurricane season. The official National Hurricane Center forecast released Thursday says the season is likely to be near or above normal.

CNN’s Judson Jones contributed to this story.