These maps break down January tornadoes based on where they begin.

january-tornado-touchdown-conus-grid

There have been about 100 more tornadoes in January than December throughout modern history. But as with most of the winter, the overall story is a quiet one.

Our most active zones during the month typically reside across the South and Mississippi Valley.

The present-day average for twisters during January is about 3 dozen. Even the coldest times of year often contain at least a handful of tornadoes.

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Tornadoes sweep through the Pilger, NE area in June 2014. (Aaron Rigsby via Flickr)

Tornadoes sweep through the Pilger, NE area in June 2014. (Aaron Rigsby via Flickr)

This is the first of a three part series that covers the basics on how to forecast tornadoes. In this post I’ll concentrate on the general necessary ingredients needed for a tornado to form.

Part two will examine the surface and low-level features in the horizontal layers (mostly meaning boundaries), and part three will discuss what you can look for that might hurt tornado development.

NOTE: This is NOT a guide to storm chasing. It is meant for forecasting purposes only. The series reflects what is needed for a typical supercell tornado, and does not necessarily match what is needed for landspouts or waterspouts.

Wind Shear

Wind shear creates spin. Tornadoes spin. So naturally, you want more wind shear to create more spin. However, there are a lot of subtleties to how the wind changes with height that can drastically alter how favorable a setup is for producing tornadoes.

In the most general sense, you want wind speeds to increase with height, and you want them to veer — change direction — with height. Veering in the northern hemisphere means the wind direction moves clockwise (i.e. south to west to north) as you gain altitude. Wind shear helps shape a thunderstorm’s updraft and gives it rotation. It is the most critical ingredient to creating a tornadic supercell.

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A nightmare before Christmas arrived in the form of deadly tornadoes across parts of the South on Tuesday.

It appears that Mississippi, where several deaths have been reported, was hardest hit.

Weird to have damaging and deadly tornadoes around the holidays? Or at all during winter for that matter… right? Sort of, but not too weird.

winter-tornado-deaths

The area of southern Mississippi where at least four likely tornado deaths occurred is part of a zone where December tornadoes are expected more often than other spots across the country during the month.

It’s also not far removed from specific tracks of prior deadly winter tornadoes. Quick note: In all cases here, winter refers to December-February — meteorological winter, and coinciding with the lowest three months of tornado activity on average. 

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2014 was not your normal year when it comes to tornadoes. In fact, early counts put it down there — hand-in-hand with 2012 and 2013 — among the least active on record.

On the whole, that’s a good thing for those who may face threats from these beasts of nature, though several high-impact events still did unfortunately occur.

Related: Top tornado videos of 2013 | Top tornado videos of 2012

Despite the lack of numbers, 2014 will be remembered for a long time to come, largely thanks to three days in June. Additional memorable tornadoes were peppered throughout the year.

February 20, 2014 – EF0 near Jacksonville, Illinois
by Dan Robinson

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These maps break down December tornadoes based on where they begin.

december-tornado-touchdown-conus-grid

Though tornado season lasts all year, it’s often hard to remember that in December. The monthly average is only about two dozen twisters across the entire country.

Numbers remain very low through the winter months as moisture-laden air is often hard to come by. Like other cool-season months, the most regular tornado activity during December resides close to the relative warmth of the Gulf of Mexico.

The areas of greatest concentration — spanning mainly parts of the mid-South — are not too different than November. But as with November seeing a contraction of land coverage compared to October, we see additional shrinking of “tornado country” during December.

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These maps break down November tornadoes based on where they begin.

november-tornado-touchdown-conus-grid

There’s a slight uptick in overall tornadoes moving from October to November, though numbers remain meager compared to the heart of the season in spring and early summer.

The month is often hit-or-miss outside some normal activity nearer the Gulf. However, some of the second season attributes can be seen on the grid map above.

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These maps break down October tornadoes based on where they begin.

october-tornado-touchdown-conus-grid

Often considered part of the “second season” which sometimes occurs in fall, tornado activity is significantly down by October when compared to the yearly peak in spring and early summer.

By October, tornado territory is dwindling with the encroachment south of colder and drier air, plus tropical season peak is behind us.

Outside larger outbreaks that occur at random, a trend of fairly few tornadoes generally closer to the Gulf of Mexico becomes the norm around this time of year. U.S. tornadoes never really fully disappear, they just wane significantly.

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First, let’s call Into the Storm what it is: A low-budget, CGI heavy, summer disaster flick meant to draw those seeking a relatively cheap thrill.

(Warner Brothers)

A wedge tornado slams Silverton High School as students race away in buses. (Warner Brothers)

On that basis, the movie delivers.

If you’re a tornado aficionado, you might be left wanting to see more action, less side story, and perhaps a little more in the way of realism.

In essence, your ultimate view really depends on what you’re in the theater for and perhaps additionally what kind of weather nerd you might be.

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Weather Geeks hosts Chris Warren (left) and Dr. Marshall Shepard (right) pose with the show's first guest, Dr. Charles Doswell (center) on the Weather Geeks set.

Weather Geeks hosts Chris Warren (left) and Dr. Marshall Shepard (right) pose with the show’s first guest, Dr. Charles Doswell (center) on the Weather Geeks set. Source

My first reaction upon hearing about the premiere of a new weather-based talk show on The Weather Channel (TWC) was a mix of shock, excitement and skepticism.

The long-standing trend of TWC to shoehorn content with little to no weather focus into their TV programming and their web site has been really off-putting for me, and to have a show like this seemingly pop up out of nowhere was a shock to the system.

For those of you who are familiar with the online show WeatherBrains, Weather Geeks can mostly be boiled down to a nationally-televised version of that.

Could this new show be a sort of redemption for TWC in the eyes of weather enthusiasts like myself who have grown leery towards what TWC has become in recent years? In some ways, that’s how it was seemingly advertised: “A show produced by Meteorologists, for Weather Geeks.” That is the tagline on their Twitter account. Welly, welly, well! We shall see about that.

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On June 16, 2014 a family of tornadoes dropped from a parent supercell moving over northeast Nebraska. It was only the beginning of a multi-day tornadic event in the region. But the supercell near Pilger, NE was the most dramatic of the event and arguably the supercell of the tornado season.

First let’s talk about the large scale meteorological setup. On the 16th, an upper level storm system moving in from the pacific ocean fueled an area of lower pressure on the east side of the Rocky mountains. These two systems, combined with their slow movement, made for a mix of atmospheric ingredients that was favorable for supercells and tornadoes for multiple days. These ingredients, namely instability and wind shear we’re known well in advance and were highlighted by National Weather Service forecast offices, the Storm Prediction Center and our tornado threat forecast.

The Setup
On Monday morning the Storm Prediction Center, known as the SPC, issued their morning outlook for the day ahead. They mentioned a moderate risk for the Eastern Nebraska area saying that

“The severe threat ultimately may be greatest from Northern Kansas into Central/Eastern Nebraska…” and “Given the potent combination of buoyancy and shear in this region…significant hail and tornadoes could occur.”

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