Truth or Urban Legend: Does Florida Get More Tornadoes at Night?

[Miriam Lawrence]

Over in Chase Reports, in the Florida tornado thread, Mark Farnik posted the following as part of a longer post:

I take some small comfort in the fact the tornado missed Orlando this time. Sooner or later, though, the Orlando metro will get hit by a significant tornado; the city lies right smack dab in the middle of a mini tornado alley prone to violent, nighttime tornado outbreaks. It's not a matter of if, just a matter of when...

Is this in fact true? And if so, what is the exact meteorological explanation? I've heard it more than once, from at least semi-reliable sources. For example, this comes from the Florida Division of Emergency Management page on tornadoes (http://www.floridadisaster.org/hwa03/tornado.htm), emphasis mine:

Over most of the nation large killer tornadoes tend to occur in the late afternoon and early evening hours. This is due to the afternoon buildup of heat in the lower atmosphere that lingers into the early nighttime hours. Florida is different. Tornado climatology shows us that strong to violent tornadoes are just as likely to occur after midnight as they are in the afternoon. This unique feature makes these tornadoes more dangerous, because most people are asleep after midnight and do not receive warnings relayed by commercial radio or television.​

Is this premise true? Are there really more strong tornadoes at night in Florida than elsewhere in the country? And if so, why?

I'm typically a lurker here, most definitely NOT a meteorological expert, so I'm sure this is an overly simplistic or just plain wrong explanation, but the only thing I can think of is that because Florida is so narrow, humid, and tropical, that air doesn't cool as much at night as it does elsewhere, and therefore the night air is more capable of fueling strong tornadoes. Is this correct?

 

[Justin E. Reed]

YES

Florida is well-known for nighttime tornadoes. Yes, many come ashore as former waterspouts almost every week in the state. Many ingredients that cause the large tornadoes in the plains during the day, are persistent over night due to it being surrounded by water, warm at that. Overall, if you look at the large outbreaks in Florida's history, you find many things in common. They seem to occur during moderate to strong El Nino years, (i.e. this year and 1998). The strongest ones, also follow this trend, although a few rare renigades break away, mainly due to hurricanes. The biggest outbreaks have almost entirely occur in the Tampa, Orlando, and Dayton Beach metro areas, all due to the motion of the parent storm system. Usually, a low pressure develops along the coast of LA the day before, then sweeps ENE/NE thru out the day, and by night, the dynamics move over Florida. The air over Florida, is almost always warm and moist, which is a important ingredient in this process, along with a crap load of others. 3 F-4's have struck Florida, all in Central Florida, ironically in the vicinity of the Orlando Metro, and most F-3s as well. This just happens to be the most heavily struck area of the state, due to location, ingredients, and timing.

I storm spotted the last outbreak, it broke my heart seeing debris fall outta the sky at I-4 & 1-95. I simply called NWS Melbourne, telling my report, and this is a direct quote," Melbourne, I am a spotter at 95&4 and I have debris literally falling out of the sky, leaves insulation, metal and bits of boards, I think a touchdown happened just west of my location." "Yes we have had many reports of funnels, this confirms a touchdown somewhere near DeLand, we appreciate this very much, big sigh, this is not a good situation, I';m sure we'll have fatalities, thank you very much"