Monday, November 9, 2015

Midwest Severe Weather Outbreak Due Wednesday

NOAA's Storm Prediction Center outlines areas under
threat for severe weather Wednesday. 
Parts of the Midwest, especially Missouri, southern Illinois and northern Arkansas, are bracing for an outbreak of tornadoes and severe thunderstorms on Wednesday.

This could be the biggest round of nasty twisters and storms the nation has seen in weeks or months.

The typical height of the tornado season is the late spring and early summer, when strong sun energizes the atmosphere, and hefty storm systems can add spin, suck up hot, humid air from the Gulf of Mexico, and pull down chilly, wintry air from Canada.

These are most of the ingredients you need for a severe weather outbreak.

Once you get into the summer, the contrasts of air masses isn't so great, and you don't get big, strong low pressure systems moving into the Plains to set off tornado outbreaks.

You still get tornadoes in the summer, but usually not many big ones at once.

In the fall, we start to get strong low pressure systems moving into the middle of the country again. The sun's strength is much weaker, and that's one reason why these autumn storms don't usually cause a lot of tornadoes.

Still, some of these autumn storms are pretty damn dynamic, and can cause big severe weather outbreaks. Forecasters are worried that one such developing storm has the potential to do this.

Autumn tornado and severe weather outbreaks can be deadly. Just two years ago, on November 18, 2013, a huge outbreak of tornadoes - as many as 81 of them - swept the Midwest. One, an EF4, destroyed about 250 or so homes in Washington, Illinois.

The tornadoes and a squall line that race to the East Coast in this outbreak killed 11 people and caused a bit over a billion dollars in damage.
Aerial view of damage in
Washington, Illinois after
 a November, 2013 EF4 tornado. 

You can watch the terror inside one of these homes destroyed by one of the November, 2013 tornadoes in Washington, Illinois in the video at the bottom of this post.

There have been other immense November tornado outbreaks in recent years, including 105 tornadoes in November, 1992 and 93 tornadoes in November, 2004. 

We have a strong El Nino this year, and that can encourage unusually dynamic and strong storm systems across the southern United States this fall and winter.

This gives us the potential for more tornadoes - more than the small numbers we usually get - along the Gulf Coast states and Florida over the winter.

As for Wednesday's expected storm outbreak, the devil as always, is still in the details.

As is the case with many of these types of storms, especially in the autumn, the storms could rapidly form into a squall line, which could possibly reduce the number of tornadoes but still cause widespread wind damage.

A number of the storms within such a squall line could maintain rotation, and continue to spin off tornadoes.

If you live anywhere in the Midwest and Tennessee Valley, keep an eye to the sky and an ear to NOAA weather radio or other reliable media to listen for tornado or severe storm warning.

If they tell you to hide in your basement, get into a sturdy building or take any similar precautions, just do it. The life you save might be your own.

The two people in this scary tornado video from November, 2013 survived exactly because they fled to the basement. You see the guy filming the tornado, then joining his daughter in the basement, the screen goes black as you hear them terrified in the basement, then they emerge after the tornado passes to see what's left of the house:

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