Severe Weather: Second Season

Storms started before the sun rose Wednesday morning and continued to push east as a cold front sweep across the south and into the southeast.  A preliminary 16 tornadoes were reported yesterday killing at least 5 and injury many more.

Typically when we think of 'severe weather season' the spring time comes to mind, not November.  But, did you know that there is actually a second spike in severe weather towards the end of October and during the month of November?  That's right!  The southern states typically see a 'bump' in severe weather during this time...just like what was experienced Wednesday.

The jetstream tends to get a little stronger during the late fall as it shifts further south pulling down colder air from the north.  This causes strong fronts and upper air systems to move across the U.S. and when you have the contrast between the warm, moist air to the south and the cold, dry air moving in from the north that's usually when you see the strongest of the storms. 

When looking at the year as a whole you will see a greater number of severe weather outbreaks during the spring than in the fall.  The days are longer in the spring and summer and there is more time for daytime heating (creating instability) to occur.  In the fall, the days grow shorter cutting off the max afternoon heating.  Second, warmer air aloft is typically found in the fall because the months leading up to October and November have warmed the atmosphere  In the spring we're coming out of winter and that's when you usually find the cold air several thousand feet above.  And you need that cold air above to get storms to rapidly develop.  Warmer air above usually limits thunderstorm potential.  It will be interesting to see how things play out going into the winter season with a strengthened La Nina once again.