BIRMINGHAM, Ala. — Strong storms pushed into northwest Alabama from Mississippi with possible twisters and heavy rains Monday during the opening round of what forecasters said would be waves of severe weather lasting until mid-week.
No major damage was reported immediately, and officials tried to reduce the chances of injuries and deaths by closing many schools and offices before storms arrived.
Police said dozens of people gathered in a community storm shelter in Haleyville, about 80 miles northwest of Birmingham, as storms approached. A scientific team from the University of Alabama in Huntsville tweeted a photo of an apparent tornado forming in Russellville.
Tornado warnings began popping up on weather maps in Alabama as soon as storms crossed the Mississippi state line from Tupelo, where the weather service said a twister touched down.
The National Weather Service issued a tornado watch for most of north Alabama, and the entire state was under a flash flood watch.
Afternoon temperatures reached the low 80s, adding energy to the atmosphere and potentially more fury.
More than 50 school systems shut down early in the state's northern half as a precaution against having children and workers on the road in buses and cars when the storms arrived. Several cities closed municipal offices early, and some schools in east-central Alabama plan to delay opening on Tuesday morning, when storms are forecast there.
Forecasters said there was a high risk of tornadoes, damaging straight-line winds, hail and flooding.
The threat of dangerous weather jangled nerves a day after the three-year anniversary of the historic outbreak of more than 60 tornadoes that killed more than 250 across the state on April 27, 2011.
George Grabryan, director of emergency management for Florence and Lauderdale County in northwest Alabama, said 16 shelters opened before storms moved in and people were calling nervously with questions about the weather.
"There's a lot of sensitivity up here," said Grabryan. "I've got a stack of messages here from people, many of them new to the area, wanting to know where the closest shelters are."
Twisters killed at least 15 people in Arkansas and Oklahoma on Sunday, and forecasters said the system moving into Alabama could generate tornadoes with strength ratings of EF-3 or higher and damage tracks 30 miles long or worse.
"Northwest Alabama is the area of the highest threat. That doesn't mean there's not a threat in other areas," said John De Block, a meteorologist with the National Weather Service office in central Alabama.
While the severe weather might not be as widespread as the April 27 outbreak, the possibility of twisters after nightfall made the threat particularly ominous.
"From my perceptive the nighttime tornadoes are the worst-case scenarios," said De Block, in charge of warning coordination in the Birmingham-area weather service office.