Microbursts, tornadoes and straight-line winds

April 14, 2012 tornado in Kansas

I was asked to write about what a microburst is. I thought I would take it one more step and talk about microburst, tornadoes and straight line winds.

A microburst is a small yet very intense downdraft that descends to the ground resulting in a strong wind divergence. The size of a microburst is typically less than 4 kilometers across. In miles that is between 2 to 3 miles. 2 miles is 3.218688 kilometers. Microbursts are capable of producing winds of more than 100 mph causing significant damage. EF 1 tornado speeds range between 86 and 109 MPH.

For more information on wind speeds or tornadoes go to http://www.spc.noaa.gov/faq/tornado/ef-scale.html . Most microbursts don’t last longer than about 8 minutes.

Derechos are common in the Midwest and they are found a lot in fast-moving band of severe thunderstorms in the form of a squall line usually taking the form of a bow echo. Derechos blow in the direction of movement of their associated storms. Severe derecho wind is anything over 57 MPH, however winds can reach over 100 MPH at times. I chased a severe wind event this year near Kirksville, MO that caused a lot of damage in its wake. I saw trees down signs blown off buildings windows broken and more in a few small towns northwest of Kirksville and in Kirksville itself. Damage was also reported form spotters in and around Hannibal MO.

A tornado is a powerful column of winds spiraling around a center of low atmospheric pressure. The winds inside a tornado spiral upward and inward with a lot of speed and power, winds inside a tornado can spin around at speeds up to 500 miles an hour, but usually travels at roughly 300 miles an hour. This makes the tornado one of the most dangerous storms.

Most tornadoes are small and have a short life span lasting only a few minutes if not a few seconds/ however some grow large and be on the ground for over a hour!

Tornadoes are not only one of the most amazing storms in the US they are also one of the most dangerous. Not only are tornadoes hard to predict, they can be hard to see. In high precipitation supercells, tornadoes can become “rain wrapped”, where the rain is so heavy it makes the tornado very hard to see if not impossible and yet the tornado is still there. That is why it is so important that you NOT go outside and wait until you see it to take cover.

Several conditions are required for the development of tornadoes. Abundant low level moisture is necessary to contribute to the development of a thunderstorm, and a "trigger" (perhaps a cold front or other low level zone of converging winds) is needed to lift the moist air aloft. Once the air begins to rise and becomes saturated, it will continue rising to great heights to produce a thunderstorm cloud, if the atmosphere is unstable. An unstable atmosphere is one where the temperature decreases rapidly with height. Atmospheric instability can also occur when dry air overlays moist air near the earth's surface. Finally, tornadoes usually form in areas where winds at all levels of the atmosphere are not only strong, but also turn with height in a clockwise or veering direction.

A tornado watch means conditions are favorable for the formation of a tornado in and around the watch area. During a tornado watch people should keep apprised of rapidly changing weather conditions.

A tornado warning means that a tornado is imminent or occurring within the specified area. A tornado warning can be issued either because of a Doppler radar indicated threat or because a tornado was reported by trained weather spotters or storm chasers, as well as emergency management personnel.

A tornado emergency is enhanced wording used by the National Weather Service (NWS) during significant tornado occurrences in highly populated areas. Although it is not a new warning type from the NWS. Tornado emergency generally means that significant, widespread damage is expected to continue and a high likelihood of numerous fatalities is expected with a large, strong to violent tornado.

~ Cody

Joplin Tornado: May 22, 2011

The day of the Joplin tornado started off like any other day of chasing. I spent about a hour looking at forecast models and talking to people about good target areas. We decided that due to time and money we were going to chase close to home instead of driving to southern Missouri.

So we started our chase going north toward Moberly, MO. We chased a storm around in Randolph County for an hour or so and then jumped over to a warned cell in Howard County, where we saw a very nice rope tornado.

It very quickly moved behind the trees and we were unable to capture video. We tried every road we could find to get back to the tornado but were unable to get there in time.

We got on a couple more warned cells in the area but they were both HP cells and if there was a tornado it was much too rain wrapped to tell.

We decided to find a gas station and fuel up and regroup. At this point we made a heart sinking discovery. We pulled up the radar image of the cell just west of Joplin and our hearts went into our guts we saw a very strong hook and reports from Twitter that debris ball was showing up on radar.

Seconds later we saw reports of a very strong and damaging tornado on the ground and moving toward a direct hit on Joplin, MO.

I can still remember the feeling. I lost all desire for chasing. All I wanted to do was push the pedal to the floor and drive south and not stop until I got to Joplin.

We decided to make one more run at a warned cell east of Moberly, but just a few minutes into the chase we all realized that two things were true.

Number one, we had fallen too far behind and with darkness settling in the chase was over. xx Number two was that our want and drive was no longer on chasing; it was on helping the people of Joplin that needed the help more than ever. As soon as I was in Columbia I started rounding up anyone who wanted to go to Joplin to help. My friend Chris T. said to pick him up in Kansas City, MO, and he would go. I told him to pack a bag and I would be there in 2 hours. I went home. And as soon as I walked in the door I threw my bag on the bed and packed a change of clothes, a few snacks, water and my vest. I walked out the door and was on my way.

We stopped at a Wal-Mart on our way to Joplin and bought cases and cases and cases of water, because the reports on the radio said they needed that the most.

When we got into Joplin, at first I saw normal damage such as power lines and down tree limbs broken. But the further we got into Joplin, the worse it got. The only way I can describe what I saw is complete devastation! I looked like a bomb had gone off and I couldn’t even speak there was no words to express how I felt.

We drove past Lowes to Home Depot, where we were told a command post was. The Home Depot was 100% destroyed! They told us the command post was moved to Lowes, so we returned there, only to be told we were yet again sent to the wrong place. This time they told us since we were medical trained that we needed to go to the 911 Command Post by the fire station.

On our way to the new location we passed buildings that were gone, cars thrown into buildings, trees uprooted out of the ground, power lines down and random stuff scattered everywhere.

I had been a firefighter for five years and have seen a lot of things, things I would not wish my worst enemy to see. But this was one of the worst if not the worst thing I had ever seen.

We arrived at the 911 command post and met some of the nicest people ever! One young lady walked us up to the fire station where we made contact with the guy in charge of search and rescue.

The fire chief told us that at dawn we would start search and rescue again and until then to nap and rest up. We walked outside and saw easily 100-plus firefighters sleeping on the grass, using anything from arms to shirts to soda bottles as pillows.

By morning there were hundreds of firefighters standing in a two-bay garage waiting to find out the grid area they would be searching. Breakfast was made for everyone but almost nobody ate. We were just ready to do what we came to do and try to find anyone alive.

We were teamed up with five more firefighters and started a house-to-house search for anyone alive that might be trapped. We spent all day looking at house after house, doing everything from cutting people out from where they were trapped to kicking in doors to check on elderly people who hadn’t been seen.

I personally worked two medical emergencies on my own, one on an older lady with back pain and a helping a lady who thought she saw a child having seizure.

After hours of searching, we saved people from being trapped and helped many people that got hurt, and worse I saw many things I hope I never see again! We worked for hours, only stopping briefly to drink water.

After working all of daylight and into the night they moved us off the search for food and rest and replaced us with fresh bodies. I would have loved to stay for days to continue helping, but I had a job to return to, and I wasn’t at all sure they would understand. So we had to call it a job well done and head home.

We stopped at Taco Bell for food half way home, and then I napped for the first time in over 24 hours, until we arrived at Kansas City.

From KC it was pedal to the metal to my own home where I took a nice warm shower and lay down. I should have fallen right to sleep but I was up for a couple hours thinking about how a person might have a warm bed now but in a matter of seconds, by a force of nature we can’t control, that can be taken from us, along with your family and friends who you love and care about.

So I want everyone to do two things:

One, tell your friends and family how much they matter to you and that you love them, because as much as we hate to admit it, in a matter of seconds you may not be able to tell them again. So tell them as much as you can, so that if the dreadful time comes you don’t have that regret.

The second thing is to ask you to please, every time you hear the tornado siren or you hear of a tornado warning close by, don’t blow it off. Take cover! I can tell you that while I was in Joplin, every time I found someone I asked where they were when it hit. Every one of them said they were taking cover. It might have been just in a hallway or in a basement, but my point is that the ones who took cover lived to rebuild the life that could have been taken from them in one second if they had not listened and taken cover.

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