This graphics shows how wind shear, or the twisting of the winds in the atmosphere, contribute to tornadic development.

A major severe weather outbreak is forecast to affect much of the middle and lower Mississippi Valley on Monday.

April 2011 has already been a month to remember in terms of severe weather outbreaks and the damage they have caused.

Just last Friday, an EF-4 ripped through the northern side of the St. Louis metro area.

So far this month, 11 of the first 23 days have each featured over 200 preliminary reports of severe weather across the country. Two of those days had over 1,000 reports of severe weather!

AccuWeather.com meteorologist Kristina Pydynowski has already warned of the multiple tornado outbreaks expected early this upcoming week from the southern Plains through the Ohio Valley.

A strong disturbance will dive into the southern Plains on Monday interacting with warm, moist air in place across the southern portion of the country. This will set the stage for a major outbreak of severe weather.

Monday’s outbreak will begin during the afternoon hours with thunderstorms firing up from eastern Oklahoma and northeastern Texas through Arkansas and the southern half of Missouri. Cities in line for dangerous weather Monday afternoon include Tyler, Texas, Little Rock, Ark., and Springfield, Mo.

Widespread damaging winds, hail to the size of baseballs, and tornadoes will all be possible. There may even be a couple of strong, long track tornadoes due to the amount of wind shear, or twisting of the winds, present in the atmosphere.

Thunderstorms will then expand into portions of the lower Ohio Valley on Monday evening and during the overnight. Severe weather will be possible across Paducah and Louisville, Ky., along with already hard-hit St. Louis, Mo.

By the evening and nighttime hours, thunderstorms will evolve into more organized lines producing widespread wind damage and large hail. Along with these threats, flooding downpours will prevail as many areas will receive multiple thunderstorms throughout the day.

Residents living from the southern Plains through the Ohio Valley should check back with AccuWeather.com frequently as this severe weather outbreak evolves on Monday.