CNN
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Parts of Central America are facing the worst thunderstorm threat in months on Wednesday as the second major storm season kicks off.

A cold front from the West will collide with extreme autumn warmth in the central and eastern US, likely producing severe thunderstorms and potentially strong tornadoes.

As a result, a Level 3 of 5 threat for severe thunderstorms has been issued by the Storm Prediction Center. More than 4 million people, including those in Kansas City and Tulsa, Oklahoma, are in this greatest threat area.

This is the first Level 3 or higher threat for Kansas City and other areas in the region since mid-July.

The storms will begin early Wednesday afternoon, but will become stronger and more widespread in the late afternoon and early evening. Potential threats include damaging winds, large hail and a few tornadoes, some of which could be EF2 or stronger.

A less significant, but more widespread level 2 of 5 The threat of severe thunderstorms is spreading from northern Texas to southern Iowa and includes Dallas and Oklahoma City. The tornado threat is lower here, but isolated tornadoes can still form and damaging winds and large hail remain a serious threat to more than 12 million people.

There is increased concern about the tornado threat given the productive year for twisters in the US. The number of tornadoes reported so far this year is the second highest on record, behind just 2,156 in 2011.

Wednesday’s tough lineup is typical of fall. Severe thunderstorms are most common in the spring and summer, but a second wave of dangerous storms and tornadoes occurs during the fall and winter, as cold air from the north often collides with warmer, moist air coming from the Gulf of Mexico flows.

But the tornado threat so far this fall has been anything but typical. The majority of the tornadoes came from Hurricanes Helene and Milton.

Milton produced dozens of tornadoes in Florida – an extraordinary number for a tropical system and the state – including the state’s strongest tornado in more than half a century and an EF3 tornado that killed several people in Polk County.