▁EF 3 ▁that ▁moved ▁across ▁areas ▁of ▁Mississippi ▁and ▁an ▁EF 2 ▁that ▁moved ▁through ▁Mobile , ▁Alabama . ▁The ▁Mobile ▁torn ado ▁dam aged ▁many ▁homes , ▁business es , ▁a ▁hospital , ▁and ▁a ▁high ▁school , ▁with ▁estimated ▁dam ages ▁total ing ▁$ 1 . 3 5 ▁million . ▁ ▁Meteor ological ▁syn opsis ▁ ▁On ▁December ▁ 2 4 , ▁the ▁Storm ▁Pred iction ▁Center ▁( SP C ) ▁issued ▁a ▁moder ate ▁risk ▁of ▁severe ▁weather , ▁valid ▁for ▁the ▁following ▁day , ▁as ▁conditions ▁became ▁favor able ▁for ▁severe ▁weather . ▁The ▁moder ate ▁risk ▁covered ▁an ▁area ▁stretch ing ▁from ▁west - central ▁Louisiana ▁to ▁west - central ▁Alabama ▁and ▁was ▁expanded ▁south ▁and ▁west ▁on ▁December   2 5 ▁to ▁include ▁cities ▁such ▁as ▁Port ▁Arthur , ▁New ▁Orleans , ▁and ▁Mobile . ▁ ▁From ▁a ▁meteor ological ▁stand point , ▁the ▁out break ▁was ▁caused ▁by ▁a ▁vig orous ▁upper - level ▁tr ough ▁that ▁moved ▁sout heast ▁into ▁Texas ▁from ▁the ▁Rock y ▁Mountains ▁on ▁the ▁evening ▁of ▁December ▁ 2 4 , ▁becoming ▁a ▁powerful , ▁neg atively - til ted ▁short wave ▁tr ough ▁on ▁December   2 5 . ▁In ▁response ▁to ▁the ▁short wave ▁tr ough , ▁a ▁surface ▁low ▁formed ▁over ▁south - central ▁Texas ▁by ▁ 1 2 0 0 ▁UTC ▁that ▁morning . ▁W arm , ▁mo ist ▁air ▁near ▁the ▁surface ▁flow ed ▁north ward ▁along ▁a ▁warm ▁front ▁extending ▁east ▁from ▁the ▁surface ▁low