A large scale severe weather event began Saturday April 26 and ended Tuesday April 29th. This system produced several waves of severe weather. Strong and violent tornadoes, very large hail, flash flooding, and damaging straight line winds accompanied this dynamic storm system. This severe weather started in the Central and Southern Plains and moved eastward into the Midwest and Lower Mississippi Valley on April 27th. The most tornadoes occurred across the Deep South as the system moved into Mississippi and Alabama on April 28th. The event finally subsided on April 29th, but not before producing significant flooding and tornadoes along the Gulf Coast, tornadoes in the Carolinas, and severe weather into the Ohio Valley and Great Lakes. The was the largest tornado outbreak in Central Alabama since the infamous weather back in April 2011.
Thunderstorms development needs the proper combination of moisture, instability and lift. If these values are combined with high enough values, severe thunderstorms can develop. Then we add wind shear, which is the directional turning of the winds with height, and tornadoes are possible. Conditions over central Alabama on Monday April 28th had the perfect mixture of these ingredients to produce tornadoes, some of which were strong.
Supercell thunderstorms developed during the late Monday afternoon over eastern Mississippi and northwest Alabama. This activity developed well ahead of a cold front in the warm sector. The activity slowly proceded east and southeast and the threat ended early Tuesday morning.
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