(Adds details on hurricane, power outages)
By Devika Krishna Kumar
MOBILE, Ala., Sept 16 (Reuters) - Hurricane Sally made landfall on Alabama's Gulf Coast on Wednesday morning as a Category Two hurricane, spreading strong winds inland across the region, shaking windows and throwing debris into roadways.
The storm is expected to cause extensive flooding, dumping nearly three feet (90 cm) of rain in some spots along the Gulf Coast, as it is moving at a glacial 3 mph (6 kph) pace.
Upon landfall at Gulf Shores, Alabama, winds were clocked at 105 miles per hour (165 km per hour), able to cause extensive damage, according to the five-step Saffir-Simpson scale. The hurricane also poses the risk of "catastrophic and life-threatening" flooding along portions of the northern Gulf Coast, the National Hurricane Center said in an advisory around 7 a.m. CDT (1200 GMT).
More than 430,000 homes and businesses were without power in Alabama and Florida early Wednesday, according to local utilities, with more outages expected.
In Mobile, Alabama, strong winds shook windows while trees and power lines swayed. The storm reminded some residents of Hurricane Ivan, which touched down near Gulf Shores exactly 16 years ago as a Category Three hurricane.
Ivan, however, was "stronger and bigger," said John, a 22-year-old resident of Mobile who was working at a hotel on Wednesday during Hurricane Sally. He wished to remain anonymous because his employer did not give him permission to speak.
Officials across the South had called on residents of low-lying areas to shelter away from the winds and rain. But for some, Hurricane Sally's slow approach brought a chance to relive childhood memories of storms past, and to witness the power of nature first-hand.
Thomas Harms braved the wind and rains on Tuesday to watch the waves crash into the Fairhope Municipal Pier, and reminisced about past storms. As a child, he went with his grandfather to see storms arrive, and he did the same on Tuesday for his son.
"It kind of takes a little bit of the fear out of it and also help you understand the dangers of it too," said Harms. "I've been kind of passing that on to my son in doing the same thing."
Damage from Sally is expected to reach $2 billion to $3 billion, said Chuck Watson of Enki Research, which tracks tropical storms and models the cost of their damage. That estimate could rise if the heaviest rainfall happens over land, Watson said.
Ports, schools and businesses were closed along the coast as Sally churned. As the storm track shifted east, ports along the Mississippi River were reopened to travel on Wednesday. But they were closed to vessel traffic from Biloxi, Mississippi, to Pascagoula, Florida.
Energy companies also shut more than a quarter of U.S. Gulf of Mexico offshore oil and gas production and some refiners halted or slowed operations. (Reporting by Devika Krishna-Kumar in Mobile, Alabama, Catherine Koppel in Fairhope, Alabama, and Jennifer Hiller in Houston; additional reporting by Stephanie Kelly and Scott DiSavino in New York; Editing by Chizu Nomiyama and Nick Zieminski)