Bogus NEXRAD?

scottd said:
The green stuff on the 496 image is definitely 100 percent from ground clutter (except for the real precip near Laredo). Take a look at the NWS regional radar image that I posted for the same time.

The folks at WxWorx (XM) do filter some of that "sparkliness" out of the raw product you may see using the NWS website such as the one I posted. Any of the returns that are less than 10 dBZ are filtered out. This will cut much of the ground clutter out, but when the clutter is strong as it was in this case, it's hard to get rid of it all. It may appear to move at times or may appear to develop and dissipate. And in the extreme cases (as I show in my workshop), the false returns may even look like thunderstorms.

I can't vouch for your other product since I don't know its source. But the 496 image is definitely ground clutter.
Click to expand...

The other product is ADS-B weather, provided free of charge by your FAA, as displayed (using Garmin Pilot) on the Asus Nexus 7 Android tablet.

Both independent sources showed the same green returns, which looked unlike any ground clutter I've ever seen. I suppose ground clutter is their excuse, but it doesn't change the fact that this sort of weather non-reporting is misleading and can lead to the development of a "boy who cried wolf" attitude amongst pilots.

Sent from my Nexus 7
 
Gosh, you have a singularly unpleasant way of making a point. Did you write the radar filtering software, or are you taking personal ownership of its failings for some other reason?

Let me try this again, for the virtue of those of us not as smart as you: The NEXRAD radar doesn't always work right, and cannot be trusted for accuracy. It's a good idea to double check it against other, more reliable sources. Someone should try to improve it, because it's misleading in its current form.

Sheesh.

Sent from my Nexus 7
 
Jay Honeck said:
Gosh, you have a singularly unpleasant way of making a point. Did you write the radar filtering software, or are you taking personal ownership of its failings for some other reason?

Let me try this again, for the virtue of those of us not as smart as you: The NEXRAD radar doesn't always work right, and cannot be trusted for accuracy. It's a good idea to double check it against other, more reliable sources. Someone should try to improve it, because it's misleading in its current form.

Sheesh.

Sent from my Nexus 7
Click to expand...

Jay, its not misleading or unreliable, if you know something about the mechanics behind it. For those who know what they are looking at, it can show very informative information that would otherwise be filtered out.

I'd suggest rather than complaining about the radar and how you think it's unreliable, that you go educate yourself on the radar systems and how they operate.
 
KSCessnaDriver said:
Jay, its not misleading or unreliable, if you know something about the mechanics behind it. For those who know what they are looking at, it can show very informative information that would otherwise be filtered out.

I'd suggest rather than complaining about the radar and how you think it's unreliable, that you go educate yourself on the radar systems and how they operate.
Click to expand...

And I would suggest that a system that displays false returns (such as I showed in the pictures, a few pages back) as often as this is flawed and less than useful.

I suspect that in our litigious world, where risk managers rule the roost, we will never see any effective filtration applied to these depictions, since to do so would be to "risk" not showing some precip, somewhere in the U.S.

In our modern hand-wringing times, it's considered far better to be wrong 50% of the time (but show false returns) instead of improving accuracy to 95%, but perhaps miss 5% of the precip. After all, no one is going to sue them for showing precip where it's not, but they will easily and quickly be sued if it doesn't show precip where it is -- even if that means setting the gain on their radars so high that it's displaying crap most of the time.
 
Jay Honeck said:
And I would suggest that a system that displays false returns (such as I showed in the pictures, a few pages back) as often as this is flawed and less than useful.

I suspect that in our litigious world, where risk managers rule the roost, we will never see any effective filtration applied to these depictions, since to do so would be to "risk" not showing some precip, somewhere in the U.S.

In our modern hand-wringing times, it's considered far better to be wrong 50% of the time (but show false returns) instead of improving accuracy to 95%, but perhaps miss 5% of the precip. After all, no one is going to sue them for showing precip where it's not, but they will easily and quickly be sued if it doesn't show precip where it is -- even if that means setting the gain on their radars so high that it's displaying crap most of the time.
Click to expand...

Technology has it's limits -- go build filtering software and better radars if you think that the current companies are doing a poor job. You'll make a killing.
 
jesse said:
Technology has it's limits -- go build filtering software and better radars if you think that the current companies are doing a poor job. You'll make a killing.
Click to expand...

I doubt it's the radar manufacturing companies that are doing a poor job. I suspect it's the risk managers who are telling the operators to keep the gain set too high so as to "miss nothing". But that's just a guess.

Sent from my Nexus 7
 
Jay, now that you're in Texas you need to know that Next ad will show swarms of bats as precip. New Braunfels is one such area...

Sent from my Galaxy Nexus using Tapatalk 2
 
Well said Scott, appreciate your insight.
 
I think Scott did a great job of explaining this.

If somebody who is uninterested in the science that underlies technology just wants to whine about technology, then they'll do it. And there's nothing that can be done except ignore them.
 
I had nexrad blotches tuesday near fort worth and indeed came through some rain en route to san antonio
 
NoHeat said:
I think Scott did a great job of explaining this.

If somebody who is uninterested in the science that underlies technology just wants to whine about technology, then they'll do it. And there's nothing that can be done except ignore them.
Click to expand...

So pointing out the failings of NEXRAD technology is now the same as being "uninterested in science"? Methinks you have a thing (or three) to learn about the scientific method.

Technology is wonderful. I have two forms of "live" weather on board, and love it. This, however, does not blind me to its limitations, nor does it make me afraid to call a spade a spade.

I have posted photographic evidence from a flight when NEXRAD was utterly, 100% inaccurate -- and the best response I've received is "that's normal", while the worst response is being accused of "whining". Brilliant.

I sincerely hope better minds are working on the problem. :rolleyes:

Sent from my Nexus 7
 
Jay Honeck said:
So pointing out the failings of NEXRAD technology is now the same as being "uninterested in science"? Methinks you have a thing (or three) to learn about the scientific method.
Click to expand...

It's not a failing Jay. I think what you fail to recognize here, is the vast area that a single radar site covers. If it's beneficial to be running a certain mode to look at something in a certain direction, while showing clutter in other areas, so be it.

Educate yourself on how the whole thing works, what having all that extra clutter in certain areas can show you in others, and I bet in the long run it will benefit you.
 
Jay Honeck said:
So pointing out the failings of NEXRAD technology is now the same as being "uninterested in science"? Methinks you have a thing (or three) to learn about the scientific method.

Technology is wonderful. I have two forms of "live" weather on board, and love it. This, however, does not blind me to its limitations, nor does it make me afraid to call a spade a spade.

I have posted photographic evidence from a flight when NEXRAD was utterly, 100% inaccurate -- and the best response I've received is "that's normal", while the worst response is being accused of "whining". Brilliant.

I sincerely hope better minds are working on the problem. :rolleyes:

Sent from my Nexus 7
Click to expand...
What you fail to recognize Jay..is you keep saying that NEXRAD was inaccurate. NEXRAD was *NOT* inaccurate.. the PRODUCT you received was inaccurate and your understandings of it were inaccurate.
 
You could just move back to Iowa where the problem is less pervasive.
Jay Honeck said:
Gosh, you have a singularly unpleasant way of making a point. Did you write the radar filtering software, or are you taking personal ownership of its failings for some other reason?

Let me try this again, for the virtue of those of us not as smart as you: The NEXRAD radar doesn't always work right, and cannot be trusted for accuracy. It's a good idea to double check it against other, more reliable sources. Someone should try to improve it, because it's misleading in its current form.

Sheesh.

Sent from my Nexus 7
Click to expand...
 
And they are hoping better minds (at least those more open to listening and learning rather than railing) are using it.

Jay Honeck said:
So pointing out the failings of NEXRAD technology is now the same as being "uninterested in science"? Methinks you have a thing (or three) to learn about the scientific method.

Technology is wonderful. I have two forms of "live" weather on board, and love it. This, however, does not blind me to its limitations, nor does it make me afraid to call a spade a spade.

I have posted photographic evidence from a flight when NEXRAD was utterly, 100% inaccurate -- and the best response I've received is "that's normal", while the worst response is being accused of "whining". Brilliant.

I sincerely hope better minds are working on the problem. :rolleyes:

Sent from my Nexus 7
Click to expand...
 
I am going to apologize for my rant first. Sorry. Now for the rant.

I was led to believe that NEXRAD is just one tool in a large toolbox of devices and methods to help me avoid bad weather. I personally am getting somewhat tired of some of these threads where pilots have abandoned our training and have become totally dependent on the magic of electronics. To talk about Nexrad being inaccurate so that they are not sued because the incompentent pilot(and he/she is truly incompentent) utilized only Nexrad data to avoid bad weather and crashed as a result of the data ignores the basis of at least my pilot training. I fly in southwest florida where the weather changes more often than not. It would stupid of me to depend only on Nexrad. In addition, to Nexrad, Stormscope, XM weather, Metars, TAF's, PIREPS, ATC, (add to my list), I utilize my ability to look out my windshield to see where the bad weather is. In IMC sure it is more difficult, and I have to depend on the adjuvant methods, but in VMC there is no excuse for getting into trouble by not avoiding bad weather, if you are concentrating on flying the plane and looking out the windshield and analyzing what you are seeing you should be able to avoid the bad weather 100% of the time.

Maybe I am wrong. I hope not.

One other rant. Flying is inherently a dangerous activity. As a result we should be (as my contractor friends often tell me) measuring twice (and maybe three times), and cutting once. I have seen way too many NTSB reports that start out with the words "...the pilot's failure to..." My first job when I fly is to make sure that I do everything possible and utilize everything available to avoid that. I owe that to myself, my family, my friends, and my fellow pilots. If I cannot do at least that then my plane should not be leaving the hangar that day. Thus I have a low threshhold for scrapping flights.

Again sorry about my rants.

Doug
 
I'm not a radar or weather guy, but some engineering one liners come to mind:

* There are entire populations who devote their careers to improving any given piece of technology. Avoid hubris; do you really think you're the first person to notice a given problem?
* All of the easy problems have already been solved.
* There are no solutions, only tradeoffs.
* Making marginal Pareto improvements is hard; making revolutionary improvements is harder.
* Balancing sensitivity vs. specificity is hard.
* Balancing spatial and temporal resolution is hard.
* Dealing with noise is hard, particularly when you need results in real time and you won't know what the "right" answer was until later, if ever.
* Sensor fusion is hard, especially across different grids and time scales, and especially when sensors can disagree.
* There is value in knowing which solutions work well, but there is also value in knowing which solutions work poorly, as this helps you from exploring unfruitful paths or going in circles.
* When something that should be easy seems hard, you're probably doing it wrong. Conversely, beware simple solutions to complex problems.
* A poor workman blames his tools.
 
You guys are HILARIOUS! Thanks for a good morning chuckle.

Of COURSE the radar is reporting exactly what it is seeing! Did you really think that I believed otherwise? Golly, maybe it sees dead people, too? :rolleyes:

And then there is the usual guy that goes off on a rant about how we pilots shouldn't rely on a single weather source, blah, blah, blah. Ya think? ;)

Doesn't the fact that what NEXRAD is seeing (in my examples) is deceptive and not really precipitation bother you? Let's not talk about THAT. "That's entirely normal. Nothing to see here...".

Well, of COURSE it's "entirely normal" -- that's my point. But, here, let me say it again, slowly, for all you engineering types: If you've got a radar system where it's "entirely normal" to show stuff that isn't really there, you've got a less-than stellar radar system.

(Cue the savants who will now cry "But it IS really there!". :rolleyes:)

Yes, we can work around this problem by cross-checking with other weather sources (which is exactly what we do every time we fly, over 100 times each year), but the point of the thread is to highlight NEXRAD's inherent problems. Saying these problems are "normal" is obvious and unhelpful -- not that I actually expected anyone to have a solution. But I did expect a more intelligent and less condescending conversation.

Sent from my Nexus 7
 
Jay Honeck said:
You guys are HILARIOUS! Thanks for a good morning chuckle.

Of COURSE the radar is reporting exactly what it is seeing! Did you really think that I believed otherwise? Golly, maybe it sees dead people, too? :rolleyes:

And then there is the usual guy that goes off on a rant about how we pilots shouldn't rely on a single weather source, blah, blah, blah. Ya think? ;)

Doesn't the fact that what NEXRAD is seeing (in my examples) is deceptive and not really precipitation bother you? Let's not talk about THAT. "That's entirely normal. Nothing to see here...".

Well, of COURSE it's "entirely normal" -- that's my point. But, here, let me say it again, slowly, for all you engineering types: If you've got a radar system where it's "entirely normal" to show stuff that isn't really there, you've got a less-than stellar radar system.

(Cue the savants who will now cry "But it IS really there!". :rolleyes:)

Yes, we can work around this problem by cross-checking with other weather sources (which is exactly what we do every time we fly, over 100 times each year), but the point of the thread is to highlight NEXRAD's inherent problems. Saying these problems are "normal" is obvious and unhelpful -- not that I actually expected anyone to have a solution. But I did expect a more intelligent and less condescending conversation.

Sent from my Nexus 7
Click to expand...
The problem Jay isn't that the NEXRAD is reporting things that aren't there..THEY ARE THERE. The NEXRAD is doing what its supposed to be doing. You don't want the government filtering things..you want them to just provide the most raw data they can.

THEN companies take that data and apply whatever filtering they want. You should be mad at XM for providing you wiht a radar feed you don't like. It's not the fault of NEXRAD..it's the fault of the XM not filtering to the degree you personally want.
 
scottd said:
Yeah, he doesn't appreciate the valid reasons why other users want to see that clutter. It was designed to identify more than just real precipitation. When you eliminate the clutter you filter out useful information in some cases. Personally, I don't want them to filter out a gust front...that's kind of an important detail.
Click to expand...

I'm sure glad you guys aren't in the medical profession.

Me: "Doctor, I think I'm dying!"

Doctor: "Why yes, so you are. But don't worry about it -- it's normal."

:D



Sent from my Nexus 7
 
scottd said:
The thing is that we're not talking about the medical profession. We're discussing weather which IS my profession. I have tried to make it easy for you to understand the underlying issue, but you are not making ANY attempt to open your mind to a different reality. The reality is simple...the product you want exists. There are lots of websites that do a fantastic job filtering out all of the returns you think are bogus. Some may be free and others may require a fee.

The key element that you don't seem to understand is that the WSR-88D NEXRAD Doppler radar itself is designed to provide just about everything it sees because there are indeed many users (not just aviation interests and meteorologists) that rely on that data (even the data you see as bogus). From a trained eye, insect, bat and bird population/migration can be tracked in that clutter. As I've said a number of times, gust fronts, sea breezes and outflow boundaries can be tracked using that bogus data. All of this data is important and filtering it out at the radar site would produce an inferior product. As I said above, if you only want just the real precipitation, there are sites that provide this kind of image. But understand that no filtering algorithm is perfect and there is a risk that real precipitation will be filtered out and some clutter still may slip through.

If you can accept this, I'll be more than happy to answer other questions. If not, then as they say on the Shark Tank, "I'm out."
Click to expand...

I understand your "reality" perfectly. It just sucks, especially if you want to use NEXRAD for weather avoidance.

No one I know much cares to track bat migration whilst trying to navigate to brunch. If its a filtration problem with both XM and ADS-B, as you state, well we need to be aiming our suggestions toward those two entities. Thanks for pointing me in the correct direction.

Sent from my Nexus 7
 
Jay Honeck said:
I understand your "reality" perfectly. It just sucks, especially if you want to use NEXRAD for weather avoidance.

No one I know much cares to track bat migration whilst trying to navigate to brunch. If its a filtration problem with both XM and ADS-B, as you state, well we need to be aiming our suggestions toward those two entities. Thanks for pointing me in the correct direction.

Sent from my Nexus 7
Click to expand...

A gust front sounds like some weather I might like to avoid or at least know about. :dunno:
 
JoeSelch said:
A gust front sounds like some weather I might like to avoid or at least know about. :dunno:
Click to expand...

I, for one, have no idea what a gust front would look like on my 496 nor have I ever heard of or met anyone who would use in-cockpit XM weather for such avoidance. You're grasping at straws, now.

Sent from my Nexus 7
 
As long as my XM weather doesn't filter out the yellow or red stuff I'm happy.
 
scottd said:
I hate to break the bad news, but it can and does filter high dBZ returns including severe thunderstorms. I have captured dozens of cases like this. That is the risk of aggressive filtering.
Click to expand...

Well that doesn't make a whole lot of sense to filter so much that significant returns get filtered out. Hopefully whoever is deciding the level of filtering has more commonsense than to do that.
 
Scott,

I think we all know this is all your fault, just as Jay is obviously at fault for all of the problems you've had with motels.

Jay Honeck said:
So pointing out the failings of NEXRAD technology is now the same as being "uninterested in science"? Methinks you have a thing (or three) to learn about the scientific method.

Technology is wonderful. I have two forms of "live" weather on board, and love it. This, however, does not blind me to its limitations, nor does it make me afraid to call a spade a spade.

I have posted photographic evidence from a flight when NEXRAD was utterly, 100% inaccurate -- and the best response I've received is "that's normal", while the worst response is being accused of "whining". Brilliant.

I sincerely hope better minds are working on the problem. :rolleyes:

Sent from my Nexus 7
Click to expand...

scottd said:
Well, if you re-read my post (#80) carefully you'll notice I don't say you can see a gust front on XM weather - that's because a gust front is filtered out (like my words seem to be filtered out when you read them). That's the problem with a highly filtered image...you lose these very valuable details.

You can see them on the NWS radar mosaic in some cases because they don't filter it out.
Click to expand...
 
Jay Honeck said:
So pointing out the failings of NEXRAD technology is now the same as being "uninterested in science"? Methinks you have a thing (or three) to learn about the scientific method.

Technology is wonderful. I have two forms of "live" weather on board, and love it. This, however, does not blind me to its limitations, nor does it make me afraid to call a spade a spade.

I have posted photographic evidence from a flight when NEXRAD was utterly, 100% inaccurate -- and the best response I've received is "that's normal", while the worst response is being accused of "whining". Brilliant.

I sincerely hope better minds are working on the problem. :rolleyes:
Click to expand...

The condescension and arrogance in this post could only come from one person....

Scott, thank you for helping the rest of us understand Nexrad...
 
scottd said:
You are welcome.
Click to expand...

Let me also add my thanks to you Scott. Great information and well presented. For what it's worth, Jay is just doing the only thing that gets him attention: p***ing people off. (sigh)
 
scottd said:
You are welcome.
Click to expand...

I'd add my thanks as well. I was fortunate enough to take a class a couple years ago, in the course of my applied meteorology minor course of study, that was nothing but satellite and radar interpretation. I'm familiar with some of the basics of clutter that one can see, but had never seen anything quite like that indianapolis radar image set you posted.
 
I have a link on the home page of my website http://www.stormscopes.com for the NTSB saftey alert regarding the potential amount of time difference between actual radar observed conditions and the age displayed in the cockpit.
 
You must log in or register to reply here.
Back
Top