| Above: Radar composite of Tropical Depression Alberto at 11:25 am EDT May 29, 2018. The center of the storm was in northern Alabama, and Alberto was headed north at 12 mph. |
Alberto was downgraded to a subtropical depression on Tuesday morning after making landfall at 5 pm EDT Monday afternoon in the Florida Panhandle near Laguna Beach as a subtropical storm with maximum sustained winds near 45 mph. Alberto peaked with 65 mph sustained winds while it was still well offshore in the Gulf of Mexico. The highest wind gust over land from Alberto was 59 mph at Tyndall Air Force Base, 12 miles east of Panama City, Florida. A number of coastal locations in South Florida and the Florida Panhandle recorded gusts of 40 – 45 mph.
Subtropical Storm #Alberto about to make landfall in #Florida - #GOES16 VIS pic.twitter.com/FAlJDYmz3H
— Dan Lindsey (@DanLindsey77) May 28, 2018
According to weather.com, Alberto’s winds were responsible for toppling a tree in Polk County, North Carolina, which killed a news anchor and photojournalist who were covering the impact of the storm’s rains. The storm also caused power outages in Alabama that affected at least 22,000 customers.
As of Tuesday morning, Alberto had dumped rainfall amounts of 2 – 4” over a large area of the Southeast U.S., with isolated areas of Florida, Georgia, and Alabama receiving over 6”. However, these rains were causing little in the way of river flooding. According to the National Weather Service, fewer than 5% of the river gauges in the Southeast U.S. were at minor flood stage on Tuesday, and no gauges were at moderate or major flood stage. According to the 11 am EDT Tuesday National Weather Service storm summary for Alberto, here were the highest rainfall amounts for each state:
9.88”: Morland, Alabama
8.69”: Okeechobee, Florida
6.10”: Louisville, Georgia
5.53”: Highland, North Carolina
5.21”: McComb, Mississippi
3.35”: Mount Leconte, Tennessee
2.96”: Anderson County Airport, South Carolina
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Figure 1. Observed precipitation for the 7-day period ending at 8 am EDT May 29, 2018. Alberto brought widespread rainfall amounts of 2 – 4” to the Southeast U.S., with isolated areas of Florida, Georgia, and Alabama receiving over 6”. Image credit: National Weather Service. |
Record amounts of atmospheric moisture from Alberto
Alberto was bringing record to near-record amounts of water vapor along its path. The 8 am EDT Tuesday upper air sounding from Birmingham, Alabama recorded 2.33” of precipitable water—their highest amount of moisture ever recorded in May, in records going back to the 1940s. The nearby Atlanta sounding had 2.15” of precipitable water at 8am Tuesday--tied for the highest amount of moisture ever recorded in May.
Early Tuesday afternoon, Alberto was a subtropical depression in northern Alabama, churning its way northward at 12 mph. Alberto was expected to dump additional heavy rains of 2 – 6” from North Florida through Alabama, the southern Appalachians and into the Great Lakes on Tuesday through Thursday. Flash flood watches were posted for portions of Alabama, Tennessee, Georgia and Kentucky on Tuesday.
Morning view of Subtropical Depression #Alberto as it makes its way through central Alabama. @NOAA #GOESEast pic.twitter.com/nSbmjZtafe
— NASA SPoRT (@NASA_SPoRT) May 29, 2018
What’s next?
The long-range predictions from the GFS and European models are not showing any tropical cyclones developing in the Atlantic over the next ten days. Both models are predicting that the Eastern Pacific could see something develop off the southeast coast of Mexico late next week, but that is too far in the future to be a reliable forecast. On Thursday, Colorado State (CSU) releases their latest Atlantic seasonal hurricane forecast, and we’ll have more to say on what the rest of the hurricane season might hold then.
Bob Henson contributed to this post.
