Can radar be deceiving at times

[STurner]

When it comes to chasing most of you look for a classic hook echo on a supercell when chasing tornadoes . I know very little about CAPE, LLC's, and SRH etc. I only know numerically what would make a good setup for a chase but do not understand when it comes to reading graphs, hodographs, and other maps that you chasers use to catch storms. I am just wondering if there have been several occassions when a storm did not look so great on radar but turned out to be a very catastrophic event. It may have even been deceiving enough to fool experts. Is there any tornado events that you can think of that were strong/violent even though it may have not been obvious on radar.

 

[rdale]

We actually look more for rotation within the velocity pattern, the "hook echo" is something used in the past before Doppler.

 

[Aaron Kennedy]

ya.. in my thesis work, only ~20% of hook echoes had a tornado associated with them at the time. Many other storms are completely rain wrapped or embedded in lines (the SE US comes to mind) and it's often hard to even distinguish any sort of appendage.

 

[Jason Harris]

So then, conversely, what percentage of storms producing tornadoes had a hook echo? Statistically also what's the record for storms that produce EF/F 0-5 to be detectable in terms of TVS, strength of rotation, etc.? Has anyone determined a likely strength of doppler-detectable rotation-to-tornado strength ratio? Also, how often has the radar worked as a reliable indicator for storms producing non-meso tornadoes or satellite tornadoes? Will we eventually have more vehicles around like the DOW in the fire depts. or homeland security or skywarn or ____ depts. for major cities? Expensive no doubt. How about flying a drone with radar. Ok, all over the place. Blame the headcold.

 

[Ryan McGinnis]

When it comes to chasing most of you look for a classic hook echo on a supercell when chasing tornadoes . I know very little about CAPE, LLC's, and SRH etc. I only know numerically what would make a good setup for a chase but do not understand when it comes to reading graphs, hodographs, and other maps that you chasers use to catch storms. I am just wondering if there have been several occassions when a storm did not look so great on radar but turned out to be a very catastrophic event. It may have even been deceiving enough to fool experts. Is there any tornado events that you can think of that were strong/violent even though it may have not been obvious on radar.

I can't think of any catastrophic examples, but I can think of one instance when I saw large, rotating, high-based LP storm with a large wall cloud and a small funnel -- that barely even registered on radar. As in, the entire storm was nearly invisible to radar until it split and transitioned into a classic supercell. If I were chasing based on radar alone and not camping on a field of congested cumulus I noticed on the sat images, it's a storm I would have missed altogether.

 

[Doug Raflik]

May 15th, 1999, Stockton, KS comes to my mind. A large tornado was on the ground for 14 minutes. 2 minutes after it lifted, a warning came out. This was not due to lack of anyone reporting it, as the road was lined with chasers, and I remember many reports of chasers calling the tornado in. I speculate that based on radar, NWS wrote off the first couple reports thinking there was no way this storm had a tornado on it. Here is what the storm looked like during the time of the tornado...

I was not shooting pictures at this time, but you can see what this tornado looked like and read a bit about it on Roger Edwards page here...
http://www.stormeyes.org/tornado/SkyPix/stktn05.htm

Here is a picture from his page...

And as Roger writes, the storm was GONE 30 minutes after the tornado was gone.

Doug Raflik

 

[craig buchanan]

One of the things that you have to remember about Radar is that there are only a few of them nation wide. Due to the fact that the beam spreads as it leaves the dish and the Earth curves, the further the radar is from the storm, the less detail and the higher up you see. To see the classic hook echo, you have to be close enough for the radar to see the rain whipping around the tornado itself. Also, if you are far away, you are looking higher up the storm and up there you may not have rotation since a tornado happens in the lower parts of the storm.
In general, for a chase, it is all that boring math stuff that keeps so many people out of meteorology that makes a good chaser. A good chaser has to be a good forecaster, because if you waited until radar indicated even a bad storm, chances are you will not be able to drive to it.

 

[rdale]

One of the things that you have to remember about Radar is that there are only a few of them nation wide.

About 150 (180ish when all the TDWR's are online, plus probably 150+ TV radars) but what's 10000% difference between friends

To see the classic hook echo, you have to be close enough for the radar to see the rain whipping around the tornado itself.

No, that's not what the hook echo is.

In general, for a chase, it is all that boring math stuff that keeps so many people out of meteorology that makes a good chaser.

In the words of the great Britney Spears...

"HUH?"

A good chaser has to be a good forecaster, because if you waited until radar indicated even a bad storm, chances are you will not be able to drive to it.

...and to be a good forecaster, you need a knowledge of meteorology. Knowing math actually improves your abilities to forecast. It's not the determining factor by any stretch, but to say that having a meteorology education actually makes you a worse forecaster and bad chaser is WAY off base.

 

[Bob Hartig]

Craig, good points about distance, curvature of the earth, and resolution. To clarify, though, radar rarely reveals the actual tornado. When you see radar couplets, what you're viewing first and foremost is a mesocyclone, which may or may not contain a tornado. There are times when reflectivity indicates a debris knob, but my understanding is that such instances are uncommon. Moreover, circulation at higher tilts as well as lower is important for establishing deep circulation, which is one of the hallmarks of a mesocyclone.

 

[John Wetter]

I think to sum up everything here... Radar is an awesome tool and can tell you a lot about a storm. But, as with all tools, there are a specific set of caveats that the radar operator must be aware of when interrogating a storm. I don't think it's fair to state the question as 'Can radar be deceiving at times?'. Of course it can! But more times than not it is giving you crucial information that you couldn't otherwise get from a storm... Is it fallible? Of course it is! Can things be on the radar but may not be apparent to the operator? Of course! I would hope that everyone looks at it as just another tool. Remember the three main inputs to the warning process? Radar-Environment-Spotters.

As far as chasing, I don't think you can ever be a really successful chaser without having at least a decent understanding of the main environmental characteristics. As far as a hook echo, when I see that on radar, I more or less think it just looks cool. It's more about the velocity image than anything at that point and after you've looked at storms visually enough, you can tell what it's generally doing out in the field.

There have been plenty of events where it wasn't 'obvious' on radar... Most cold core events are tough to spot on radar, especially if there is any distance at all from the radar site. Environmental characteristics have to be watched there. Warn on forecast anyone? Also, if you're just looking at reflectivity, you'll miss nearly all tornadoes from QLCS's. You can spot them on velocity and even more so now with super resolution. I can think of a decent number of instances where radar didn't tell the whole story. Was it necessarily wrong? No. It just didn't give enough information for the whole situation.

 

[Terry Tyler]

rdale is right, while hooks may give away alot as far as tornado potential there is not always a hook present especially in situations such as doug explained...ive seen some storms with incredible hooks that i could not believe werent tornado warned, but they didnt have what it took to make a tornado...sometimes, close to the center of a low you can get weak thunderstorms to form that dont look too appealing on radar but are producing tornadoes because of the extreme level of shearing in the atmosphere...sometimes, you cant even see them on velocity which is why its extremely critical for spotters to be on such events...

a classic example of why you cant always rely on seeing a hook would be 12/9/08 near yazoo city...storms were beggining to form a squall line and were embedded in rain and stratus extremely hindering visual observations and the ability to view hooks out of reflectivity images...take a look at the reflectivity below...you can barely see a notch, and definatly no hook...however, if you take a look at the cooresponding SRV image you will see a couplet that was turned out to be a 29 mile EF-2...

as im sure you are aware, the brighter colors indicate stronger winds...when you get a cluster of bright pixels next to eachother, that is called a couplet...it reveals alot more then meets the eye, especially in a situation with HP storms or ones that are embedded in rain like this...sometimes, its wise to use a higher level scan...there are 4 scans, 0.5, 1.5, 2.5, and 3.5 degrees above the horizon...if you keep it at the default scan of 0.5 you are seeing the lowest "slice" of the atmosphere...if you scan a notch above you can sometimes scan above the radar clutter, or rain and look for features in the mid and upper levels of the storm...

assessing the environment of the storm, monitoring reports coming in from EMA and spotters in the field, looking at different elevation scans, and being aware of the expected potential of severity will help you better interpret the data for each individual cell...

radar can be extremely deceiving, but with some good education on what you see out there they arent that hard to discern...you can see anything from dust, birds, smoke, buildings, mountains, bats or anything else that beam hits...thats why spotters are a critical part of the warning decision process...

 

[STurner]

I believe a tornado emergency was issued for Yazoo City. Is this because experts believed this tornado from looking on radar may have been capable of EF3+ damage. There were some discussion in other threads on the Breckenridge, Texas tornado from April 9, 2008. I but know very little but that looked like a classic definition of a hook echo that looked like it had a violent tornado in it even though it was rated EF1. I also did not get to follow the entire Super Tuesday Outbreak because I was so tired and went to bed around 1:00am. Did any of those nighttime EF4 tornadoes come out of an embedded squall lines or did they come out of classic supercells as well?

 

[craig buchanan]

About 150 (180ish when all the TDWR's are online, plus probably 150+ TV radars) but what's 10000% difference between friends

Even adding in all the WD88's owned by TV/Radio stations and terminal Dopplers, I would argue there are still relatively few radar's installed nation wide when you consider how big this country is. Perhaps I am more sensitive since I live in one of these holes...

My point about math and meteorology is that when you ask high school students about majors they think a met. degree sounds pretty cool. Then they see the math lineup and head for something less math intensive... Like engineering... lol

And, lastly, I was not meaning to say that having a meteorology degree was a determent at all. Just the opposite. Almost every great chaser I know has at least a Bachelors in Meteorology and several have a PHD.

I will admit, I phrased things very poorly in this post. Have to remember to not post before at least one dose of coffee.

 

[craig buchanan]

To clarify, though, radar rarely reveals the actual tornado. When you see radar couplets, what you're viewing first and foremost is a mesocyclone, which may or may not contain a tornado.

Good point. This is why I used to have a rule about never posting to any forum first thing in the morning. Things come out all wrong.

There are times when reflectivity indicates a debris knob, but my understanding is that such instances are uncommon.

One of Dr. Kloesel's presentations I saw actually did have debris you could detect in the radar image. I think it was from one of the Moore tornado's that got close to the Twin Lakes tower. I will definitely consed that this would be the only true way of using radar to detect a tornado.

Moreover, circulation at higher tilts as well as lower is important for establishing deep circulation, which is one of the hallmarks of a mesocyclone.

Again, very true. I know there is money being pumped in to a couple of projects to try and find a good way to display this type of information effectively just for this very reason.