Calm Before The Storms

The recent severe weather in the southeast and midwest has subsided, at least for now. Here in Colorado, we have not seen many violent storms so far in 2011. What is the reason for this? One probable culprit is La Nina. While most of us meteorologists caution against blaming local weather patterns on global phenomena, in this case I feel the need to point to La Nina for our unusually calm and cool May.

NOAA and the National Weather Service do an amazing job of tracking the El Nino/La Nina pattern. The latest data shows that La Nina is continuing to weaken, and sea surface temperatures in the eastern Pacific are rising. For most of the early spring 2011, the Jet Stream was draped across California and on through the southern parts of the USA. This gave Colorado some much-needed moisture, and cool temperatures. All that is about to change.

As La Nina continues to weaken, we can expect the Jet Stream to be pushed farther north, with expanding high pressure over the Great Basin. For Colorado, this has several important implications. First, we should see temperatures begin to warm rapidly. This will melt the significant snowpack in the mountains, and could cause river flooding. Second, weather disturbances may dip across northeast Colorado from the Pacific Northwest, causing an increase in thunderstorms over the plains. This means wind, rain, hail and possibly tornadoes.

Colorado's peak severe weather season is late May through the end of June, however we can experience severe thunderstorms all the way into October. Most of the latest data on La Nina points to more precipitation over Colorado as we head into June.

This is good news for storm chasers, such as myself. Those of us who venture out onto the plains in the spring and summer to photograph and video severe weather are looking forward to the month of June. One important caveat to this is my personal hope for the safety of everyone on the plains. Most storm chasers do not want to see people hurt or killed, or property destroyed. I even worry about livestock exposed to hail and lightning.

If you've been intrigued about this year's EF-5 tornadoes in the south and midwest, you may be thinking about going out on your own to chase thunderstorms this summer. I'm going to repeat some information I posted here in 2009 about "Safe Chasing":

1.) Learn all you can about severe weather before you go out.

2.) Chase with an experienced partner.
3.) Do not stop on the road. Slow down and pull way off to the side.
4.) Use your flashers when stopped on the roadside.
5.) Do not speed through small towns. Besides the possibility of running over a
small child, local law enforcement is usually wary of storm chasers and they will bust you.
6.) Avoid eating while driving. This is an unnecessary distraction.
7.) Do not text or blog while driving. Yes, I have seen chasers doing this!
8.) Get a hands-free cell phone headset or earpiece. You need both hands to drive.
9.) Don't core punch your first time out.
10.) Save your camera and video recorder for when you stop.
11.) Watch the other chasers and drivers around you.

12.) If someone is driving recklessly, report them.

Those of us who have years of storm chasing experience are not trying to discourage new chasers. What we are trying to do is keep you, and everyone else, safe.

Whether you are interested in chasing storms or not, you should be very aware how fast Colorado's weather can change. If you check the forecast once a week, you are going to miss some important information. We at Channel 7 keep a very close eye on changing weather, and we encourage you to watch our weathercasts, and check our website every day for the very latest information and safety tips. I can be reached at steve.hamilton@mac.com if you have any questions at all.

Thanks!

What Happened In Joplin, MO?

The strength and violence of the Joplin, MO tornado that hit last Sunday raises some important questions for safety planners and residents who live in tornado-prone areas. These questions are: Finding adequate shelter, and believability of tornado warnings.

The National Weather Service issued a "Tornado Warning" for the Joplin area 23 minutes ahead of the first reported touchdown. This gave residents a decent amount of time to find adequate shelter. The questions then become, "What is adequate shelter?" and "Is this a real tornado, or another false alarm?"

In my opinion, the NWS did a great job of providing adequate lead time for the local residents. Sirens were blaring over 20 minutes ahead of the disaster. We can explore the above issues a bit further by simply looking at the images of the devastation. One challenge is, how often does this magnitude of tornado hit any one particular area? We haven't seen one single tornado do this kind of damage, with so much loss of life, since the 1950s. For every EF-5 tornado that hits a populated area, there are hundreds of others that pass harmlessly around big towns and cities. This fact can cause disbelief or denial amongst people in highly-populated areas. I saw one interview on CNN where the victim said "I never thought this could happen to me."

As a meteorologist, and a broadcaster, this is one of the most troubling things to hear from people. Now we know, these things can happen to anyone living in a tornado-prone area.

So, those of us who communicate severe weather warnings to the public have to keep in mind how we address the issue to those who are listening and watching on radio and TV. My observations have shown the range of human emotions in life-threatening weather, including fear, apathy, wonder, disbelief and denial. It's important that people facing powerful weather understand the dangers, and understand that tornadoes do not choose who they affect. Tornadoes are pure acts of Nature, indiscriminate in their destruction. Getting people to believe this fact is another story, and raises an entirely new set of issues, which I will address in my next posting.

The other point that has been on my mind is 'adequate' shelter. At least some of the broadcasters and meteorologists in the Joplin area were telling people that they must seek shelter underground. EF-5 tornadoes have wind speeds of over 200 mph. We are talking about winds that are moving debris at the speed of an Indy race car. Humans cannot survive such an environment without 'adequate' protection. What is adequate protection from an EF-5?

Tests have been done for years with cannons and 2x4s against various types of housing. A piece of wood propelled at 200 mph easily penetrates drywall, press-board, most housing siding and even brick walls. The typical home is constructed of exactly these same materials. Additionally, the power of EF-5 winds will often completely remove residential homes from their foundations and destroy them in-flight, along with anyone in them.

I personally had the chance to view the damage done by the Greensburg, KS EF-5 tornado from May 4-5, 2007. Even though the death toll was much lower, the damage was just as great. I saw many concrete pads completely scoured, houses thrown into the air and dropped many yards away with vehicles on top of them, coins buried deep into tree trunks. Again, EF-5 forces are not survivable by humans, unless there is adequate shelter.

Simply put, being above ground during such a powerful tornado is a death sentence. Generally 'adequate shelter' from an EF-5 means being under ground, supposedly in a basement. Even this is no sure-fire guarantee of safety because the structure above the basement can collapse into it if the roof is removed. So, then we are talking about a basement with some sort of heavy structure in it, allowing the occupants to crouch under and avoid the wind-driven debris, and then whatever falls into the basement following the tornado.

Trailer homes and automobiles of any kind, including large trucks and SUVs are completely unsafe in almost any strong tornado, let alone an EF-5.

Many homes in the Joplin area, to say nothing of the rest of the Midwest, do not have basements. Some have crawl-spaces, but due to the high water table, sometimes a basement is not practical. What then? There are companies now that make 'safe rooms' that are designed to withstand the forces of 200 mph winds and debris, yet are located above-ground. Some people without basements are having these installed. They essentially consist of a large concrete block with a steel door. People get inside and ride out the storm. I've seen images of a concrete foundation with nothing else on it except the safe room. Unfortunately, these types of structures are not affordable by everyone, to say nothing of folks who occupy trailer homes in parks that do not provide concrete or underground safety areas.

It may seem that all I've done here is raise a lot of questions and concerns. This, to me, is a good place to start. In my next posting, I'll share some research on safe rooms and the power of strong tornadoes, and what makes them tick. Thanks.

2011: The Year Of The EF-5

Greetings, storm chasing enthusiasts. I hope you will understand that my excitement for the new storm season is tempered with the ever-growing casualty lists from towns across the South and Midwest. When I chase storms and tornadoes, at the forefront of my mind are the people under those storms who are losing property, and sometimes their lives. We must remember to keep everything in perspective about what we are doing out there. While storm chasers are vital in documenting meteorological occurrences, in my opinion it is critical for all storm chasers to maintain a certain level of stoicism regarding the destruction wrought by storms. (Photo credit: www.tornadovideos.net)

There has been much criticism of a video released last week documenting the Joplin, MO tornado, where chasers are heard yelling profanity-laced descriptions in the background. Granted, that tornado was huge, and bound to generate excitement. However, many professional and scientific chasers thought the verbiage was inappropriate, considering how many people lost their lives in Joplin, (125 as of this posting). I will tell you from personal experience that it is difficult to control one's emotions in the presence of such violent weather, so I see both sides of the issue. As storm chasers, we have to decide what is, and more importantly what is not, appropriate behavior, when we release storm video.

2011 is on track to become a record tornado year for the United States, not only in the number of tornadoes, but also in the number of EF-5s being recorded. The Joplin tornado was upgraded to an EF-5 yesterday (May 24, 2011).

If you are unfamiliar with the "Enhanced Fujita" or EF scale, please hit this link:
http://www.spc.noaa.gov/faq/tornado/ef-scale.html

Several EF-5s were recorded in last month's outbreak across Alabama, Tennessee and Georgia.

Why are this year's tornadoes so violent? First, the interaction between storm systems and the Jet Stream has made for several outbreak situations in recent weeks. Often in the early to mid spring, the Jet Stream is still far enough south to coincide with the passage of low pressure and frontal systems. The Jet Stream is a major player in thunderstorm evolution. If we get an active Jet Stream flow (50 knots or higher) above an area primed for thunderstorm growth, some of the major storm elements become enhanced. Speed and directional shear, and lift, are increased by strong Jet Stream winds. In the case of the recent tornado outbreaks, the Polar Jet, which circles the Earth at 7-12 km (23,000 - 39,000 feet) and separates major cold and warm air masses, was present. Digging further into this phenomenon, there were significant "jet maxes" crossing the prime thunderstorm areas during the outbreaks. A jet max is an area of particularly strong winds, embedded within the Jet Stream itself, say over 110 knots. In meteorology, we divide jet maxes up into quadrants, so picture an oval divided into quarters. In the left-front and right-rear quadrants of a jet max, we often see enhanced lift and shear.

The recent weakening of the La Nina phenomenon in the Pacific may also be a contributor. During La Nina springs, a large ridge forms over the western USA, serving to push the jet stream farther north. La Nina has weakened significantly in recent weeks, and the Polar Jet Stream has stayed far to the south. This means the Jet has been crossing the Deep South and the Southern Plains, and interacting with thunderstorms more frequently than usual.

Strong Jet Stream winds in the vicinity of large thunderstorms serves to enhance lift by evacuating air from the top of the thunderstorm. This air must be replaced with something, and often air is pulled from below, thereby enhancing lift. Shear is also enhanced because the Jet Stream usually provides strong southwesterly winds in the mid and upper levels. Combined with adequate surface winds from the southeast, the two wind vectors cross each other and give a "twist" to the atmosphere within a thunderstorm, enhancing growth and severity.

Many storm chasers I speak with are expecting a very active June for Colorado's eastern plains. We will be out there, providing images, video and accounts of whatever takes place.

Okla-HAIL-Mo, May 16, 2010

Wow, what a wicked day for folks in the Oklahoma City area on Sunday 5/16. A massive hailstorm approached the area from the northwest in the mid-afternoon, dropping hailstones the size of softballs. Major damage was reported throughout the area, including smashed windows and windshields, large dents in vehicles, and some injuries.

My chase centered west of the hailstorm, in the Hinton and Binger, OK areas. The reason for this is I wanted to stay out of the huge hail, and photograph some interesting storm formations. The storms west of OKC were less-severe, but more photogenic.

Moving east from Amarillo, TX in the early afternoon, I was able to intercept a developing super-cell thunderstorm near Hinton around 3:30 p.m. This storm initially did not look threatening, however it quickly developed into a rotating super-cell, dropping golf ball sized hail, and a beautiful structure. I will be posting photos of this storm later today.

Today, Monday May 17, I will be chasing to the west of Amarillo, out toward Albuquerque, NM.

Stay tuned!

Chasing In Texas Oil Country

On Friday May 14, the chase centered around Kermit, Odessa and Midland, Texas with storms forming along a stationary front draped across the area along I-20 in the southwest part of the state. It was a good old fashioned Texas wild-goose-chase across the oil fields and several tornadoes were sighted by Roger Hill and Tony Laubach.

Coming in from the north, I had a long drive from Amarillo that morning so I positioned myself to catch the western-most storms in the line. Quite often, the storms forming at the end of the line can quickly produce tornadoes, and are sometimes quite photogenic as there are no storms behind them to interfere with light quality and contrast for photos and video.

This area of southwest Texas is dotted with oil drilling platforms and has the distinct odor of crude oil mixed with mesquite. An interesting smell, to be sure. The countryside is mostly flat, providing a great view of thunderstorm updraft bases for miles around.

Taking I-27 south to Lubbock and then proceeding southwest from there along smaller roads, I was able to intercept several thunderstorms. The weather situation in the area was dominated by a stationary front. North of the front, temperatures were in the 50s with fog and drizzle. South of the front, readings reached the upper 60s with high dewpoints. There was also a low-level jet of 30 knots crossing the front at a favorable angle. When you have dynamics like that, you can be fairly certain that storms will form.

Proceeding south toward Kermit, TX, I was able to navigate safely through one thunderstorm "hail core". A hail core is the part of a thunderstorm where the largest hail is falling, usually some distance away from the updraft. Hail was golf ball sized and my vehicle sustained several dings. Once south of the hail and rain, I sighted the storm's updraft base. I immediately recognized that the updraft was rotating and potentially tornadic. You can see the rotation in the images I've posted.

I encountered "chaser convergence" along Highway 115 near Kermit. The "TIV" or Tornado Intercept Vehicle (Tornado Tank) was there along with several of the Doppler-On-Wheels vehicles from various research teams including the National Science Foundation. Numerous amateur chasers were sighted along the roads as well. Fortunately, everyone played nice and I did not encounter any rude or unsafe chasers.

Locking in on the Kermit storm as the best looking one in the area, I decided to engage it. I positioned myself just north of I-20 and found good paved roads for a beautiful view of the storm structure, while staying out of the large hail that was falling. Visible to the northwest was the storm's rotating updraft which had "TVS" or Tornado Vortex Signatures embedded within the structure. A TVS is radar-indicated rotation. This was a classic super-cell updraft with strong inflow bands and beautiful sculpted striations, indicative of moderate wind shear.

After stopping four or five times at various points for photos, I disengaged around 4:30 p.m. CDT and began the long trek back up to Amarillo, where all my clothes were located! I arrived back at my hotel around midnight.

Folks, this is what serious storm chasing is all about. You get up early and forecast your target, then drive to get there, (four hours in this case). The chase lasted almost three hours, followed by a four hour drive back. Obviously, anticipation and positioning are key to avoiding long drives, but sometimes it cannot be avoided.

I've been out now since last Monday and running out of clean clothing. Today (Saturday May 15 will be a marginal day in the Amarillo area, however some storms may move out of New Mexico in the afternoon toward this area. Sunday 5/16 looks interesting east of here out toward Wichita Falls.

This has been a very successful week, however the weather pattern will be changing soon for the Great Plains. We are forecasting a high pressure ridge to move into the area next week, squelching the chances for severe thunderstorms.

Wild Day In Oklahoma, May 10 2010

Good Day Everyone. Monday May 10, 2010 will go down as an infamous day in Oklahoma tornado history. Thanks to a powerful low pressure system with strong dynamics, high dewpoints and good wind shear, we had numerous strong thunderstorms with tornadoes across northern Oklahoma. Unfortunately, several people lost their lives. My chase day began in Goodland, KS and ended in Wichita, KS. A five-hour drive out I-70 and then down I-35 brought me in range of one of the strongest storms by 4 p.m. I moved in from the north to get position in "The Notch", which is an area on the leading edge of the storm with strong air inflow. Since I was coming in from the north, my best chance to see any tornadoes would be in the notch.

I got there in the nick of time and found myself directly under the mesocyclone, or the strongest area of rotation. To my great relief there was only one other chaser there! The tornado was rain-wrapped by that time, and thus invisible. Finding myself in the perfect position to get run over by the tornado, I skedaddled to the south to try and get around the southern edge of the thunderstorm and perhaps glimpse a tornado from the south. Moving back off the country roads to I-35, I headed out of the storm just before ten tractor-trailers were blown off the roadway. I quickly turned to see the dissipating tornado and then started back north on I-35, stopping to assist several truckers whose rigs were overturned. Several trees had been uprooted as well. This damage was done either by a tornado, or the extremely strong rear-flank downdraft winds coming around the south side of the storm.

Needless to say, it was a very exciting 30 minutes! Fortunately none of the truckers I encountered were injured. Several trucks had blown over onto other vehicles, but everyone was fine. Today I head out of Wichita for the Tulsa area to play along the existing frontal boundary. There will be favorable conditions for a few super-cells today.

Stay tuned and stay safe!

The Hunt Begins 2010

Hello fellow storm enthusiasts. Here we are at the end of March, and storm chasers are eagerly outfitting their vehicles, scheduling time off and studying long-range forecasting models in anticipation for an active chase season. We don't actually know for sure what 2010 will hold in terms of the number of tornadoes we will experience, which brings up the main point of this post.

There are all kinds of storm chasers out there. Many are in the hobby exclusively to see tornadoes. Granted, tornadoes could be considered the holy grail of storm chasing. However, if you are considering investing in photography equipment, wireless internet, laptop computers and other gear, just to see tornadoes, I would suggest that you are missing out on many other fascinating aspects of storm chasing.

In my 10 years as a chaser, I've seen perhaps 30 tornadoes. By the standards of some chasers, that's not very many. However, I do not chase storms exclusively to see tornadoes. Severe thunderstorms hold many treasures for the chaser who can appreciate the storm as an entity unto itself.

When I locate a chase-worthy thunderstorm, I look forward to the wide variety of features that I am about to experience. Being a meteorologist, I am first interested in the structure of the storm. This is best observed from several miles away. Quite often you can see striations and rotation as the storm begins to take shape. The sheer enormity of some thunderstorms is enough to spark a huge thrill of amazement. I enjoy studying how each storm is "put together". That is, how the individual elements have come together to make this giant, booming convective engine.

No two thunderstorms have ever been, nor will ever be, identical. They're all different and hold their own unique treasures. One good-sized thunderstorm could supply all the electric power needed by the United States for three or four days. Watching nature's fireworks and attempting to comprehend the power behind a single lightning stroke can be an electrifying endeavor.

Then there's the hail, the wind, the sound and the feel of being in close proximity to one of the planet's most amazing displays of atmospheric aesthetics. Just standing in the wind as the air around you is being pulled up into a thunderstorm updraft makes your senses tingle. Seeing the rain pour down, drenching parched earth and returning life to a dried out cornfield is an exhilarating experience. And if you've ever held a grapefruit-sized hailstone in your hand and felt its weight, and realized where it's been and how many times it was lifted into the sky to attain that size, you know what I'm talking about. Thunderstorms are amazing, frightening and awe-inspiring.

I will tell you that there is nothing like the thrill of seeing a tornado close-up. But I will venture forth the suggestion that tornado-hunting should not be your sole endeavor if you're going out to chase thunderstorms. Tornadoes are rare and special, but so are the other aspects of severe weather, and thunderstorms should be appreciated in their entirety, for the powerful and beautiful phenomena they are.

Happy, and SAFE, chasing!

-Steve Hamilton 3/28/2010