The severe weather season finally kicks in

Weather patterns are back on track across the eastern US, but the risk of seasonal storms increases.

Last Modified: 08 Apr 2013 10:08
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Tornadoes occur in every month across the US, but last months tornadoes were 81% lower than average [Al Jazeera]

When we talk about severe weather across the United States, we normally think of the months from March to August when thunderstorms that bring damaging winds, hail and tornadoes are almost a weekly occurrence.

For this year though, the active severe weather season is only beginning. The activity that would normally start in March was dampened by a very persistent weather pattern.

A deep trough located on the eastern side of the country meant that most of the region stayed much cooler. In order to develop the transitional severe weather, the atmosphere needs to be more fluid, allowing the warm moist air from the south to meet the cold dry air from the north.

Not until last week has the locked weather pattern finally started to move. Based on a three year average the month of March would normally see 87 tornadoes. But this year, March only had 17.

All that is now changing and we are currently in the middle of a three day severe weather outbreak. As our newest storm moved out of the Rockies, it helped to usher in cold air from the north. With each day that it moves east, warmer, more moist air is pulled in from the Gulf of Mexico. These ingredients are essential for violent thunderstorms to develop.

Every day the threat will move. On Sunday the threat was greatest over the states of Kansas, Oklahoma and Arkansas. Out of these storms golf ball-sized hail caused destruction in Kansas.

The danger areas will move slowly east each day, so on Monday potential of damaging winds, large hail and tornadoes is in northern Missouri, southern Iowa and central Kansas.

It will be on Tuesday that the weather system will have the greatest threat. Cities such as Oklahoma City and Wichita in Kansas could see dangerous and damaging weather conditions.

April tends to be the most active month for tornadoes and on average we see 368.


Al Jazeera
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