Tag Archives: doppler

Tornado Quest Science Week In Review For May 1 – 8. 2017 #HurricaneStrong

Hurricane Preparedness Week #HurricaneStrong has started for the USA. This week’s focus will be on preparing for these powerful storms. If you live in a hurricane prone region, now is the time to prepare. There are numerous websites from the National Weather Service, the American Red Cross, and FEMA that have helpful information.

For your consideration, here are this week’s links…


With the current USA’s Environmental Protection Agency now out of the climate science business, here are some good resources to keep yourself informed.

Here’s some very good renewables news. According to the American Wind Energy Association (AWEA), a new wind turbine was installed every two and a half hours in the United States during the first quarter of 2017.

Arbor Day may only officially be celebrated once a year, but in reality every day can be arbor day.

In spite of improvements in many countries, air pollution still is a substantial public health issue round the world with developing countries having the most troubles.

The contentious atmosphere (no pun intended) surrounding the current presidential administration, the USA’s Environmental Protection Agency (EPA) continues with nefarious overtones.


It’s Hurricane Preparedness Week in the USA from May 7 – 13, 2017. Now is the time to get prepared if you live in a hurricane prone region. The National Weather Service has a comprehensive hurricane preparedness website with all the information you need. On Twitter, you can also follow @NWS along the #hurricanePrep #HurricaneStrong & #ItOnlyTakesOne hashtags for more information.

Here’s a very nice infographic from the National Weather Service with a plethora of information on the WSR-88D weather radars that are an invaluable part of the forecasting and warning process.

NOAA has a very useful tool you can use to find out how climate change will affect your neighborhood.

Taking into consideration the recent changes in the Antarctic ice shelves, a major break could be imminent.

A slower rise in global temperatures from 1998 to 2012 has been hailed by climate change denialists as proof that Earth’s climate isn’t changing and future projections are irrelevant. In fact, new data show that the “hiatus” has no impact on long-term climate change projections.

Big changes in the broadcast meteorology field with the minority finally becoming the majority. Broadcast meteorologists are coming to the inevitable conclusion that they’re not only the only scientists their viewers will ever see on television, but that climate change is now a part of the essential information they must convey to their viewers.

The recent drought in California may be linked to a newly identified climate pattern.

This past week marked the eighteen anniversary of the 3 May 1999 Kansas and Oklahoma tornado outbreak, the largest outbreak to date in the history of Oklahoma. The National Severe Storms Laboratory in Norman, OK has a comprehensive retrospective with a wealth of information. And yes, it can and will happen again.

This past week also marked the tenth anniversary of the Greensburg, KS EF-5 tornado. Thanks to fast and effective warnings from the Dodge City, KS National Weather Service and good coverage by broadcast meteorologists, many people had plenty of warning. A few decades ago, a tornado of this magnitude would have resulted in dozens of fatalities.

We’ve not heard the last of this for a long, long time. “New York Times Wants To Offer Diverse Opinions. But On Climate, Facts Are Facts.”

Finally, some helpful lightning safety information courtesy the National Weather Service office in Burlington, VT. Every year approximately thirty people are killed and hundreds injured in the USA alone from lightning. Most if not all of these deaths and injuries are avoidable.

That’s a wrap for this post…see you next time!


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Tornado Quest Science Links And More For July 29 – August 5, 2016

Greetings to everyone! I hope the weather’s being good to you no matter where you live. The most responses this week have come from the article on the current “hurricane drought” in the USA. Complacency could breed a nightmare scenario. There’s plenty of other interesting topics to explore out there, so let’s get started.

For your consideration, here are this weeks links…


A nice essay on how anyone (yes, that includes you) can be a part of citizen science. It’s easy, often costs little to nothing, and covers a myriad of interests.


This has been a long time coming. The USA’s Environmental Protection Agency (EPA) has finally realized that jet aircraft exhaust is not good for our planet.

A sobering graphic that shows the almost unbelievable growth of garbage dumps across the United States in the past century.

Here’s some good renewables news! The world’s largest floating wind farm is set to open in 2021 off the coast of California.


2015 was without a doubt the warmest year on record for Earth. Here’s a look at the ten most startling facts about yet another record year for climate change.

The National Oceanic and Atmospheric Administration has just released a 300-page State Of The Climate report documenting the historic warmth of 2015 as well as scores of other aspects of last year’s climate.

The hefty report, State of the Climate in 2015, was produced by more than 450 scientists from 62 countries around the world — more than any previous edition.

What this amazing video of a lightning bold obliterating a telephone pole…then watch it again in slow motion.

Check out these amazing images. “180,000 forgotten photos reveal the future of Greenland’s ice.”

The USA hasn’t seen landfall from a hurricane since 2015. That could induce complacency…and a potentially deadly scenario. It’s only a matter of time before this “hurricane drought” and our luck runs out.

Being an atmospheric scientist and studying climate often involves working in extreme weather conditions. Do you think you’ve got what it takes? Check this out.

Thanks to climate change, a new public health hazard can’t be ignored. “Hot and humid summer weather across the U.S. brings with it the rise of the mosquito season, and this year the threat of the Zika virus makes that more than a minor nuisance.”

The “fingerprints” of climate change can be found on every corner of the globe.

A very thought-provoking essay on a infrequently discussed but irrevocable climate and global economies link.

NBC’s new storm chasing vehicles sporting doppler radars are quite interesting…and more likely a gimmick than of scientific value.


Senator Jim Inhofe’s (R-OK) granddaughter gets science and wants to know why, unlike 64 percent of the American population which have climate change concerns, Inhofe does not understand the science.

That’s a wrap for this post! I’d like to welcome my new followers in social media, glad you’re along for the fun!



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Tornado Quest Science Links And More For July 22 – 29, 2015

For much of North America, it’s been summer as usual. One notable exception is the ridge of high pressure that has parked itself over the southern plains and, for the time being, has no intentions of moving. With a rich supply of Gulf moisture, the dew points combined with temperatures in the upper 90’sF have created potentially dangerous heat indexes near or above 110F. In conditions like that, the body can easily be overcome by heat…even in people who are in the best of physical condition. As for the tropics, the Atlantic and eastern Pacific are quiet for the time being. But, it’s still very early in the hurricane season. We’re nowhere close to reaching the climatological peak. While the tropics are quiet, this is an excellent time to make sure your emergency kit is in order.

Here’s a big “thank you” to all the folks who’ve given me positive feedback about this blog and my decision (for the time being) to make it a more concise post. Like many of you, I’ve many simultaneous projects in progress, each with its own unique demands, requirements, and deadlines. On that note…

For your consideration, here are this week’s links…


Watch Neil deGrasse Tyson explain literally everything in the universe…and, in under 8 minutes!


A fascinating read on a brutal fact of injuries suffered in the 22 May 2011 Joplin, MO tornado: Soil Dwelling Fungus Rode Joplin Tornado To Unexpected Human Home.


A very interesting and eye-opening look at many modes of social media and/or messaging from the Electronic Frontier Foundation. To no one’s surprise, many of the most popular items are to be trusted the least.

One of the most annoying facts of online culture is the tendency of website designers to block password managers. “Websites, Pleas Stop Blocking Password Managers. It’s 2015.” Trust me, if there’s anything that will induce me to not revisit your site, it’s the blocking of password managers.


When the storm has passed and it becomes yesterday’s news, most of the populace assumed things are back the normal. If anything, the contrary to that delusion is the long-term truth. Hurricanes, floods, earthquakes, tornadoes, blizzards, et al. all have the same brutal psychological effects on many of the people dealing with the aftermath.


Oklahoma has a new claim to fame…and it’s nothing to do with tornadoes. Shake, frack, and roll!


A very good read from the USGS: “How Much Water Is There On, In, And Above The Earth?” Interesting to note that, “The vast majority of water on the Earth’s surface, over 96 percent, is saline water in the oceans.”


This was quite a popular story this past week, but the phenomenon isn’t uncommon. In fact, bugs, bats, birds, smoke, cold fronts, outflow boundaries, etc. are easily picked up on doppler radar and, depending on the time of day and season, is quite commonly seen.

If you missed the Tornado Forecasting Workshop this spring with Rich Thompson, you can watch them on YouTube here.

Is asking “How much rain will it take to end the drought?” too simplistic? Quite often it is.

Tornadoes occur round the world on many continents. They’re no stranger to Sweden, but it’s very rare for the Lapland region to see tornadoes in a region this far north.

Finally, I’d like to welcome my new followers…I’m really glad you’re along for the fun. Tornado Quest covers a plethora of geoscience topics that will be of interest to many. We’re here for the long haul too…so stick around for some very cool things we have in the works.


Tornado Quest Science Links And Much, Much More For April 20 – 28, 2015

After several days of active severe weather, the contiguous 48 USA states get a bit of a respite. For the most part, it will be welcome. There’s still plenty of time left to get your emergency kit for home or work in order…and this quiet period is a good time to make sure everything is in check. May is the most active tornado month (from a climatological standpoint) for North America…so we’ve still many weeks of severe weather potential ahead. With the recent spate of severe weather and several crucial deadlines garnering my time and energy, I’ve had to carefully delegate my time…ergo the brevity of this post.

For your consideration, here are this week’s posts…


Food for thought. “Can We Trust Scientists Self-Control?” In general, yes.

An excellent essay that hits the spot in “Inoculating Against Science Denial.”


A “must-read” for anyone who is online from Ghostery (which I can’t recommend highly enough). Trolls…aka online bullies…don’t just live for the change to make sophomoric comments, some lust for private data too.


A very comprehensive list of about one hundred books that cover a wide spectrum on the history of science.


The recent devastating Nepal earthquake was, by some accounts, a “nightmare waiting to happen.”

This doesn’t surprise me at all. We’re so good at causing earthquakes, the U.S. Geological Survey wants to start forecasting them.

Oklahomans feel far more earthquakes than Californians do…and the reason isn’t a surprise. Shake, frack, and roll.


This is the kind of good news I love seeing. “Like Shale Oil, Solar Power Is Shaking Up Global Energy.”

This is Air Quality Awareness Week. For many folks (depending on their local climate patterns) with health issues, this is far more important than even severe weather awareness.

2015 could be a very rough year for wildfires across the contiguous USA…and California in particular.

Our dependency on Amazon rainforests is much greater than we are aware of.

Some surprising survey results of American’s opinions on regulating CO2 and renewable energy research.


Nice overview of the current California drought and its connection to climate change.

California’s drought isn’t the end of the world, but it will change the lifestyles of people who are affected by it. Welcome to a new and permanent way of life.

Are recent extremes in weather events tied to climate change? Some studies say, “yes.”

It’s been almost a decade (October, 2005) since a major (Category 3 or stronger) hurricane has made landfall in the USA. How much longer will our luck hold out?

I couldn’t have said it better myself. “Climate change eats away at the foundation of virtually every issue Americans worry most about today: the economy, national security, good jobs and public health.”

Could seasonal tornado forecasts be on the horizon? If this is feasible, it will be interesting to see how well it works over the long term.

There’s quite a storm brewing over the National Weather Service in Birmingham, AL installing a television studio. Personally, I welcome the concept and think it’s a cracking idea!

Can doppler radar detect birds? Absolutely. It can also detect smoke from wildfires, insects, bats…and much more!

Ft Worth TX NWS GraphicA very informative graphic from the National Weather Service in Fort Worth, TX explaining why an impressive velocity couplet on radar doesn’t mean “wedge.” A long-lasting cyclic supercell moved across central TX on 26 April 2015 and produced all modes of severe weather including large hail, tornadoes, and flash flooding. Damage surveys revealed all the tornadoes that occurred were of EF-0 intensity. Evaluation of real-time storm chaser reports also reveal 1) the difficulty in accurately deciphering what chasers are seeing with only lightning to illuminate the storm and 2) the hazards for the general public of getting your warning information from unofficial (non NWS and media outlet) weather information sources.

Ft Worth TX NWS Graphic2Yes, it was a remarkable supercell with impressive fluid dynamics and behavior, but rather normal in the number of and intensity of tornadoes.


Can you put a price on the opinion of Pope Francis? Apparently some delusional opportunists think so…which is a shame. Unethical also comes to mind.

And on that note, this is a wrap! See you good folks next time!


National Institute of Standards & Technology (NIST) Technical Investigation of Joplin, MO Tornado (492 page PDF File) #mowx

There’s no doubt that the Joplin, MO tornado of 22 May 2011 was a watershed event in 21st century USA weather history. A triple digit death toll had not been seen in the USA since 1953. Since then, spotter networks, improvements in radar and warning technology had reduced the overall death tolls dramatically. In light of the 3 May 1999 Bridge Creek/Moore/OKC tornado, much speculation was generated about the potential death tolls that could result from a violent, long-track EF-4 or EF-5 moving through a large metropolitan area such as Dallas/Ft. Worth. Many people, including yours truly, assumed it would take a direct hit for a triple digit death toll to occur in contemporary society. Only then, the death tolls could possibly top 100 or more. The Joplin, MO event was a dramatic wake up call that it didn’t take a large metropolitan area suffering a direct hit from a violent tornado for a 100+ fatality death toll to occur. The Joplin metro has a population of roughly 50,000 yet had a death toll of 161 from a violent EF-5 that moved through the city during a late Sunday afternoon.

The NIST has released a technical investigation of the Joplin tornado event. While rather technical, I highly recommend it to anyone interested in the atmospheric or earth sciences. A word of caution; this is a large 492 page PDF file. The download time, depending on your internet connection and computer, may take some time. Regardless, it’s a worthwhile read with a wealth of information.

Tornado Quest Gee-O-Science Links For Oct. 12 – 20, 2013

The crispness of cool Autumn air is beginning to settle in across the Northern Hemisphere. Some areas in the contiguous 48 states have seen significant snowfall amounts. In the tropical Atlantic, one of the least active hurricane seasons in over 40 years continues. And with the US government shutdown over (for the time being), NOAA, NASA, USGS, the EPA, and other agencies are getting back into the swing of things. Unfortunately, a great deal of scientific research was put on the back burner. So, with all that in mind, lets take a look at this weeks links…


Many folks in tornado prone areas pine for public shelters. Chuck Doswell doesn’t think they’re a good idea and I very much agree.

The folks at the Capital Weather Gang wrote a very interesting article that (in spite of its unpopularity) I feel is quite valid: Beware the flaky forecasts.

National Geographic has a very nice multi-media feature on the El Reno, OK tornado of May 31, 2013 with a great overview of the Twistex team.

Here’s a very interesting read (with journal reference) on how the Earth’s rotation affects vorticies (hurricanes, tornadoes, ocean currents, etc.) in nature.

Wind energy is great and I hope becomes more the norm. Unfortunately, those spinning blades can play havoc with National Weather Service radars.


The World Health Organization has now included air pollution as a major health hazard.


Project FeederWatch is a great way to get involved in citizen science during the cold winter months. Think of it as keeping track of miniature dinosaurs!

NASA has a very cool cloud spotter app for all of you folks out there who, like me, spend a lot of our outdoor time looking at clouds.

Here’s a great article with a plethora of citizen science projects that has almost something for everyone.


When I was awestruck at the size of the Tyrannosaurus in NYC’s Museum of Natural History, I naturally assumed it was probably the largest in the world. Nope…there are bigger ones!

And that’s a wrap for this post! Hope everyone has a great week!


Tornado Quest Gee-O-Science Links For Sept. 23 – Oct 12, 2013

After a few week on hiatus due to several ongoing projects, I’ve decided to trim the Gee-O-Science weekly post down to ten links per week. Even with the best of intentions, time management can go awry. Having said that, here we go…

Here’s an excellent account of the El Reno, OK tornado of May 31, 2013: “Chasing The Beast” which no only goes into the tragic events of fatalities, but several other storm chaser accounts of events during this particularly violent tornado.

Another good read from the American Meteorological Society is this preliminary report on the role of multiple vortex structures (44 page PDF file) in the El Reno, OK tornado and it’s connection with storm researcher fatalities.

Building homes to withstand hurricane force winds is one thing, but tornadoes are something else…unless you’d like living in a steel-reinforced concrete pillbox.

NOAA is embarking on a very cool concept, using underwater robots to improve hurricane science.

The Latest IPCC Climate Change report has been out for many days, but there’s still some uncertainty on the contents. Here’s a good overview from Scientific American that was posted before the latest report was issued.

The National Snow and Ice Data Center (NSIDC) reports that Arctic sea ice minimum for 2013 is the sixth lowest on record.

Sadly enough, evolution isn’t the only science topic that’s being ostracized. Add climate change to the list.

Though not an official NOAA weather product, this ever-changing wind map is one of the coolest sites online.

Check out these amazing black and white images of the red planet.

When possible, I’ll try to include a citizen science link with every weeks post. Here’s a cool one you can try out and all you need is a computer to gather 19th century weather data.

As you can tell, some article will not be strictly related to specific geoscience topics and will often contain information on other areas of interest. Variety, especially in science, is the spice of life.

Have a great week folks….cheers!

Tornado Quest Gee-O-Science Links For July 22 – 28, 2013

With the aftermath of a derecho causing a great deal of headaches for yours truly, this has been a hectic week…so this post will be a bit on the brief side. Still, it was another interesting week in science with almost something for everyone.  Here’s a look at a few select items I managed to gather together while being without power (and air conditioning) in July.


Very well said…in comic strip form: What Science Does.

Here’s an enjoyable video on 10 unanswered science questions. Certainly food for thought.

My fellow map lovers will enjoy this: a fun look at Buckminster Fuller’s Dymaxion map updated for the 21st century.

Speaking of maps, here’s a look back on ten beautiful medieval maps.

Inspired by the Voyager 1 photo of Earth taken in 1990, Carl Sagan reflects on the pale blue dot in a 1994 interview with NPR’s Science Friday.


Sprites and blue jets, atmospheric phenomenon associated with lightning, has fascinated me for years. Here’s a great story on how a citizen scientist detected Britain’s first “lightning into space.”


What happens when phone lines are destroyed in storms? The solutions won’t be easy to find.

I highly recommend the search engine DuckDuckGo. Here’s some background info from it’s builder, Gabriel Weinberg.


Earthquakes can have devastating effects far from where they originally occurred.


The National Hurricane Center has a very nice page on Tropical Cyclone Climatology with everything you’ve ever wondered about and more.

NASA will utilize drones to gather data on tropical cyclones and related weather phenomenon.

Global warming is making life hell (literally) for firefighters.

Sub-arctic forests have recently been experiencing an increase in wildfires.

A view into the challenges of predicting sea ice cover…a daunting forecast challenge that’s often overlooked.

Interesting read on how new knowledge about permafrost can lead to more accurate climate models in the future.

Here’s a very interesting photo essay; “Adapting to climate change in arid Chile

Shortly before midnight on July 23, a derecho blasted through the Tulsa, OK metro leaving over 100,000 electricity customers without power. What is a derecho and what makes them a very unique type of thunderstorm?

Math isn’t just the universal language of science, it helped forecast the path of Hurricane Sandy.

Here’s a very interesting read on weather radar gaps and downtime. It’s a topic that has concerned me for quite some time.

Interesting read on dual radar storm analysis techniques using one radar.

Worth revisiting: The American Meteorological Society’s 2012 information statement on climate change.

Here’s an outstanding “behind-the-scenes” video overview of the devastating May, 2013 tornado events in Oklahoma from KWTV (News9) in Oklahoma City.

Finally, one of the most dramatic videos of the El Reno, Oklahoma tornado of May 31, 2013 I’ve seen. Of particular interest is the twin multiple suction vorticies at 00:42 seconds. This was previously noted by Dr. Ted Fujita in a film of the Xenia, OH tornado of April, 3, 1974. This is an incredible display of the complex nature of fluid dynamics that takes place in large & intense tornadic events. But a word of warning…being this close to any tornado is very dangerous…I never condone that behavior under any circumstances.

And that’s a wrap…have a great week everyone.


A Remarkable March Tornado Outbreak

What will likely be one of the largest (if not the largest since record keeping began in 1950) March tornado outbreaks took place on 2 March 2012. The forecast, synoptic setup, and SPC product details can be found at this link. What I have for this post are a few examples of base reflectivity (BR) and storm relative velocity (SRV) that I captured during the event. At the height of the outbreak, it was very difficult to keep up with the multiple warnings, special weather statements, spotter reports, and multiple radar sites simultaneously. In fact, my Twitter feed on Hootsuite was probably posting an incredible 150-200 ‘tweets’ per minute making it almost impossible to keep up with the flow of info. During the outbreak, I was fortunate enough to capture a few radar images and two tornado warnings.

This scan, taken at 2019Z shows two tornadic supercells back-to-back. The supercell on the right produced the Henryville, IN tornado which resulted in significant damage and several fatalities. A classic ‘hook echo’ configuration can be seen as well as what’s often referred to as a ‘debris ball.’ This results from the radar beam hitting a large amount of airborne debris that results in a high reflectivity signature.

This scan, taken at 2023Z shows the same two tornadic supercells a few minutes later. Two tornadoes were still in progress and substantial damage was taking place.

The above scan taken at 2023Z shows the Storm Relative Velocity product for the two tornadic IN supercells. Two substantial couplets can be seen at the location of the mesocyclones. On the eastern supercell, high velocity data to the right of the couplet (pink colors) may be indicative of a very strong Rear Flank Downdraft (RFD) which, according to some research, instrumental in tornado genesis.

The Severe Weather Statement issued by the Louisville, KY NWSFO expresses the nature of the situation with a Tornado Emergency.

The same sense of urgency is expressed in this Tornado Warning issued by the Wilmington, OH NWSFO for the same tornadic supercells as they moved further east.

This reflectivity scan, taken at 2301Z, shows the supercell that produced a tornado that damaged a large portion of West Liberty, KY. The scan shows a classic supercell reflectivity image with a well defined hook echo and a “debris ball” just east of West Liberty.

Once again we see very strong wording in a tornado warning…this one being from the NWSFO in Jackson, KY with emphasis on a Tornado Emergency for the warned area.

The second base reflectivity image is from 0001Z and shows a more pronounced debris ball with 70dBZ at the precipitation core as well as high values at the center of the mesocyclone.

Tornado outbreaks in March are not unheard of and there are several events in the past that have made the “top ten” lists of March events including the Tri-State tornado of 1925. This event was certainly no exception and is likely to remain in the record books for some time to come. Fortunately, with doppler radar and spotter networks, the storms were well observed which no doubt kept the death toll from being much higher. Unfortunately, a significant portion of the fatalities occurred in mobile homes…deaths that could have easily been prevented…but only when a full understanding of the dangers of remaining in fragile and cheaply built structures is finally comprehended by the public.

A Record Breaking April Tornado Outbreak

During the afternoon & evening of April 3-4, 1974, approximately 148 tornadoes occurred in an unprecedented outbreak. Tornadoes formed in thirteen states and killed approximately 330 people. Many records were set during this event including the number of tornadoes during a 24 hour period and the number of F-5 (using the old Fujita scale) tornadoes that formed in one event. It was truly a remarkable event in many ways. Information devoted to that event can be found here and here. An event that would be equal to or surpass the Superoutbreak was inevitable. That event took place on April 27, 2011 as part of a three day episode of severe weather that began in TX & OK and spread over the next two days to the east coast.

Day 1 Outlook Tornado Probability Map at 10:29 a.m. on April 27, 2011

The image above is the Day 1 Outlook Tornado Probabilities map issued by the Storm Prediction Center (SPC) at 10:29 a.m. on April 27, 2011. The map shows the likelihood of a tornado within 25 miles of a point. The hatched area, running from MS & AL to KY, shows the risk of a EF-2 tornado or higher within 25 miles of a point. As you can see, the probability of a tornado was very high in a widespread area. The area with the greatest threat at the time this product was issued was over east-central MS through central AL. For all of the forecast products issued this day, the SPC was ‘spot on’ in every instance.

Moving ahead a few hours, the visible satellite image above shows numerous supercells from MS and AL northward to KY. Cumuliform overshooting tops can be seen over the most intense updrafts and large anvils have been spread downstream by the upper level winds. Most of the storms were moving at speeds up to 50 mph. In some cases, the storms even exceeded this speed. Storms moving at such speeds leave people little time to react if they’re in the path and need to take shelter.

Now let’s take a look at several doppler radar images, both in base reflectivity (BR) and storm relative velocity (SRV) from several sites during the height of the outbreak.

Base Reflectivity Image From Birmingham at 2215 UTC

The first image was a scan from the Birmingham, AL (KBMX) National Weather Service doppler radar taken at 2215 UTC. The supercell structure is clearly evident. At this time, the tornado has just passed through the Tuscaloosa, AL metro. In the hook echo, a significant “debris ball” can be seen (purple area) as the tornado lofts tremendous amounts of debris and vegetation thousands of feet in altitude. There is a significant inflow notch visible and the flanking like has developed enough to become a substantial thunderstorm. At this point in the outbreak, there were 29 tornado warnings in effect.

Tuscaloosa Tornado From The KBMX Doppler BR & SRV At 2219 UTC

The next image is from a few minutes later. The tornado has moved further to the northeast at a speed of at least 55 kts. The debris ball is still visible on the BR image. The Storm Relative Velocity (SRV) scan shows a significant couplet with velocities of +97kts & -117kts. A couplet this substantial can almost pinpoint the location of the tornado in spite of low clouds and/or precipitation that may prevent visual confirmation of the existence of the condensation vortex.

Tuscaloosa Tornado from Birmingham KBMX doppler radar at 222 UTC 27 April 2011

By 2228, we can see the supercell has maintained a well defined hook echo. The SRV couplet is still striking in appearance. The tornado was likely at EF-4 intensity at this point and was closing in on the Birmingham metro.

KBMX Doppler Radar at 2233 UTC on 27 April 2011

A few minutes later, the tornado is northeast of Brookwood, AL and has a very well defined ‘debris ball’ on the BR image. The SRV couplet is still very pronounced with +112 kts/-110 kts of shear.

Tulsacaloosa Tornado BR & SRV at 2224 UTC 27 April 2011

A wider view at 2224 UTC shows the overall storm structure and very strong couplet moving to the northeast. The next series of scans show the storms progress towards the Birmingham, AL metro where the same tornado did a considerable amount of EF-4 damage.

Tulscaloosa/Birmingham Tornado BR & SRV from KBMX doppler radar at 2233 UTC 27 April 2011

Tulscaloosa/Birmingham tornado from KBMX BR & SRV at 2242 UTC 27 April 2011

Birmingham tornado from KBMX BR & SRV at 2255 UTC 27 April 2011

In the above scan, the ‘debris ball’ is still very clear as the tornado has maintained its intensity upon approaching Birmingham.

Tornado warnings across MS/AL/TN from KBMX BV & SRV at 2255 UTC 27 April 2011

Taking a wider view, there’s an astounding number of tornado warnings in effect. At least four distinct couplets can be seen in the SRV scan.

Birmingham tornado from KBMX BR & SRV at 2309 UTC 27 April 2011

By 2309, the tornado was making its way through the northern parts of the Birmingham metro. A strong couplet and hook echo are still visible.

Birmingham tornado from KBMX BR & SRV at 2323 UTC 27 April 2011

Birmingham-Ashville tornado from KBMX BR & SRV at 2350 UTC 27 April 2011

Birmingham-Gadsen tornado from KBMX BR & SRV at 0013 UTC 27 April 2011

Birmingham-Centre tornado from KBMX BR & SRV at 0022 UTC 27 April 2011

As the Birmingham tornado continued to the northeast, it maintained strength and a very strong SRV couplet. When the supercell reached a point southwest of Centre, AL, the storm structure had the appearance of the textbook supercell thunderstorm with a large precipitation core and a very pronounced hook echo.

The next three scans show BR & SRV from KBMX as another tornadic supercell approached the Birmingham metro at approximately 2323 UTC. Both the BR & SRV show tornadic characteristics.

Centreville/Birmgham AL tornado from KBMX doppler radar at 2323 UTC 27 April 2011

Centreville/Birmingham tornado from KBMX doppler at 2341 UTC 27 April 2011

Centreville/Birmingham tornado from KBMX doppler radar at 2355 UTC 27 April 2011

In the last scan from KBMX, it’s interesting to note that the structure is more difficult to discern in the BR scan the closer the supercell moves to the doppler radar site. Fortunately, with doppler radar, the couplet can still be clearly seen.

Brooks, GA tornado from KFFC BR & SRV doppler radar at 0412 UTC 27 April 2011

The last scan is from the Atlanta, GA doppler radar site of a tornadic supercell near Brooks, GA. This was one of several tornadic supercells that formed in GA & the Carolinas as part of this outbreak.

It’s obvious to see that the advancements made in doppler radar have made the tornado warning process more accurate. From a scientific perspective, it’s also interesting to observe the structural changes and levels of intensity some storms can maintain for very long periods of time.

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