Subtropical Storm Alberto Recap: The Second Memorial Day Landfalling Named Storm Along the Southeast Coast This Decade

Subtropical Storm Alberto became the first named storm of the 2018 Atlantic hurricane season just before midday May 25 east of Mexico's Yucatan Peninsula, eventually making landfall three days later on the Memorial Day holiday along the Florida Panhandle.

(NEWS: News Anchor, Journalist Killed Covering Alberto)

Alberto was classified as a subtropical storm, basically a hybrid between a tropical storm and a low-pressure system you would find in higher latitudes.

(MORE: What is a Subtropical Storm?)

Alberto initially battled wind shear, then as wind shear diminished in the Gulf of Mexico on May 27, Alberto ingested dry air, which kept the system from developing enough convection surrounding its core to become a tropical storm before its Memorial Day landfall.

Alberto made landfall near Laguna Beach, Florida, between Panama City Beach and Destin, late afternoon on Memorial Day 2018, becoming the second Memorial Day landfalling named storm along the Southeast coast this decade. 

Colorado State University tropical meteorologist Phil Klotzbach said Alberto was the longest-lived Atlantic named storm that formed in May in 65 years. 

(MORE: 2017 Hurricane Season Produced Most Reported Tornadoes in Nearly a Decade)

Outer rainbands from Alberto produced flash flooding in the Myrtle Beach, South Carolina, and Wilmington, North Carolina, areas on Memorial Day, when 2 to 4-plus inches of rain fell in a short period across the coastal Carolinas.

Heavy rainfall from the remnants of Alberto triggered multiple landslides and caused waterways to swell across western North Carolina's Blue Ridge Mountains on May 29, the National Weather Service reported, triggering the most significant flooding since Hurricane Frances in 2004 in McDowell County.

(MORE: Evacuations Ordered Below North Carolina Dam)

On May 30, a training band of torrential rain triggered a flash flood emergency in western Alabama, where flooding prompted evacuations of an apartment complex in the town of Eutaw.

Heavy rainfall triggered a landslide on May 30, which collapsed a home with two people inside in Boone, North Carolina. Farther north, flash flooding swept away two vehicles in Albermarle County, Virginia and two people are missing as of the morning of May 31.

Almost 10 inches of rainfall was reported in Alabama and North Carolina. Here were the highest rainfall totals by state from May 25 to May 31, according to NOAA's Weather Prediction Center:

• Alabama: 9.88 inches near Morland; 3.41 inches in Huntsville; 2.26 inches in Mobile
• Florida: 8.69 inches near Okeechobee; 4.37 inches in Key West; 3.71 inches in Miami and Fort Lauderdale; 3.61 inches in Destin/Ft. Walton Beach
• Georgia: 6.33 inches near Louisville; 4.26 inches in Augusta; 3.39 inches in Savannah
• Illinois: 6.01 inches in Glencoe; 5.0 inches in East Peoria
• Indiana: 3.75 inches near Poseyville; 3.07 inches in Evansville
• Kentucky: 3.78 inches near Cadiz; 3.77 inches in Fort Campbell; 2.73 inches in Louisville
• Louisiana: 2.63 inches in Covington; 1.24 inches in New Orleans
• Michigan: 3.57 inches near Luzerne; 2.88 inches in Belding; 2.07 inches near Kalamazoo
• Mississippi: 5.21 inches near McComb; 2.13 inches in Pascagoula
• North Carolina: 9.86 inches near Black Mountain; 6.41 inches in Wilmington; 5.04 inches in Bryson City
• South Carolina: 7.93 inches near Tryon; 4.65 inches near Walterboro; 2.33 inches in Charleston
• Tennessee: 5.82 inches near Graysville; 5.14 inches in Parsons
• Virginia: 3.12 inches in Wakefield; 2.23 inches in Norfolk
• Wisconsin: 2.68 inches near New London; 2.58 inches near Ogdensburg

The WeatherSTEM observing station at the Florida State campus in Panama City recorded a sustained wind of 43 mph on May 28. A sustained wind of 38 mph with a gust of 44 mph was observed near Apalachicola, Florida, ahead of landfall.

Several trees were downed in Montgomery and Shelby counties, Alabama, on May 29, including a tree on a home in the city of Montgomery.

Water levels north of Tampa Bay and westward to the Mississippi River Delta in Louisiana rose to 1 to 3 feet above normal tide levels ahead of and around the time of landfall.

A peak storm surge of around 3 feet was observed at Apalachicola, Florida, early to mid-afternoon on May 28.

Beaches on the Gulf side of St. George Island, east of Apalachicola, were underwater at the time of high tide on May 28, and some streets were flooded due to this storm surge. Storm-surge flooding was also reported early May 28 in St. Marks, a village on the coast south of Tallahassee, Florida. 

May Storm Origins

Tropical or subtropical storms can occasionally develop in the Atlantic Basin during May.

The Caribbean, Gulf of Mexico and the southwestern Atlantic Ocean are the most likely areas for development in May. This is illustrated on the map below, which shows the origin points for tropical storms that have formed in May since 1851, including a few that became hurricanes.

What's more unusual is to have a storm form in the Gulf of Mexico in May. That's happened only three other times in NOAA's historical database, last occurring in 1976.

Since 1950, 20 Atlantic Basin storms have developed before the start of June, according to NOAA's historical hurricane database. That's an average of roughly one storm developing before June 1 every three to four years.

Since 2012, preseason storm activity has been an outlier from the norm.

Four of the past six years have featured named storms before June 1 in the Atlantic, including 2012, 2015, 2016 and 2017. Two of those years – 2012 and 2016 – featured the genesis of two named storms before June 1.

Wind shear is generally too strong for storms to strengthen and even form during May and even into early June in the Gulf of Mexico.