"real time" or "live" Doppler radar

[dtobin123]

It seems that every weather radar feed seems to claim to be either live or in real-time, but its never quite that way. It seems that you have to wait between 2-15 minutes to get a refreshed image of a given radar feed.

Why is this the case? I remember old analog radars with their characteristic sweeping line that would constantly update the radar feed. It seems to me that newer radar systems could easily do the same thing albeit without the line. So then why on every radar feed that I can find is there minutes delay in the feed? Whether using a program like GR2/3 and other dedicated radar software, or just viewing feeds off of a TV station's Doppler it is never quite live.

Does this stem from the radar technology or does this have something to do with drawbacks in how data from the radar is transmitted?

Maybe I'm too demanding, but it just seems that when decades ago weather radar actually seemed live, weather radar of today (at least that which is accessible to the public) has taken a step backwards in its "refresh rate". Or am I just horribly wrong where the past radars with the sweeping lines weren't live as I had always though

As you can tell I'm pretty uniformed when it comes to weather radar as I've just started to get interested in all of this, but I've been really curious over this issue.

Thanks!
-Daniel

[Joe-Nathan]

Part of the reason for the "delay" is that the newer radar systems do multiple scans at multiple angles. The standard NWS doppler takes about six minutes to do this. The local TV do this also. In order for the weather peeps to get a good understanding on what is happening, they need the mutliple scans of the storm. Does this help?

Good question and first post.

Welcome to HCW!

[steve]

dtobin123 Wrote:It seems that every weather radar feed seems to claim to be either live or in real-time, but its never quite that way. It seems that you have to wait between 2-15 minutes to get a refreshed image of a given radar feed.

Why is this the case? I remember old analog radars with their characteristic sweeping line that would constantly update the radar feed. It seems to me that newer radar systems could easily do the same thing albeit without the line. So then why on every radar feed that I can find is there minutes delay in the feed? Whether using a program like GR2/3 and other dedicated radar software, or just viewing feeds off of a TV station's Doppler it is never quite live.

Does this stem from the radar technology or does this have something to do with drawbacks in how data from the radar is transmitted?

Maybe I'm too demanding, but it just seems that when decades ago weather radar actually seemed live, weather radar of today (at least that which is accessible to the public) has taken a step backwards in its "refresh rate". Or am I just horribly wrong where the past radars with the sweeping lines weren't live as I had always though

As you can tell I'm pretty uniformed when it comes to weather radar as I've just started to get interested in all of this, but I've been really curious over this issue.

Thanks!
-Daniel

I don't know about present day TV radars, but as far as Weather Service radars are concerned, you may find this link helpful. Remembering those old radars you are talking about, (I actually worked at a television station then) they did not have the capability that the present ones do, that is to look into storms. So perhaps the scan did not need to be as long.

http://www.srh.noaa.gov/srh/jetstream/do...cp_max.htm

[crossdresser]

I don't think there is such a thing called live radar.......Please correct me if I'm wrong.

[SevereWxEnthusiast]

There is such a thing as live radar, but only when one level is being scanned and displayed. This is the case with the normal view on WKRG's radar here in Mobile. However the only "live" part is what is immediatly displayed at the scan line that rotates around the screen. /aliensilv

The problem is that that method will only show info at that one level in the sky. To really see what is going on the NWS radar first does a complete rotation at about .5 degrees above the horizon, then a number of additional rotations (scans) at incrementally higher angles. As said earlier this takes about 6 minutes. Then there is a little processing time as all the echos are turned into data and crunched by the radar computer and made into meaningfull displays like base reflecitivity, doppler shift, VIL and etc. /aliensilv

one tidbit: radar does not scan straight up therefore there is a "cone of silence" around each radar station. /aliensilv

[Southernbelle]

Welcome and thanks for the great question!!