Local Weather Radar Picks up Cars traveling 130 mph

[Bru]

http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=17311&source=0

National Weather Service Doppler Radar Detecting Cars

Atmospheric conditions were right early Tuesday morning across north central Illinois for the NWS doppler radar in Romeoville to be able to pick up on traffic on Interstate 55 and 57. The doppler radar typically measures the motions of rain and water droplets toward and away from the radar, just like how a police officer's radar can pick up on a car's speed. But when a low level inversion (a layer of warmer air up above the surface) develops, it can cause the beam to be re-directed toward the ground and pick up on dense objects like buildings or traffic on highways. In this instance, the radar was able to pick up on traffic across Livingston County along I-55 as well as Iroquois County along I-57. The specs of higher returns are where the beam is being deflected back to the radar off of traffic. It may be hard to make out, but the green and blue specs along I-57 near Danforth show some in-bound velocities of 115 knots (~130mph)...hopefully this was just noise and not someone driving too fast!!! Click here for more information on how doppler radar works.

Personally, I think it's a fluke. What are the chances of two cars on the same latitude going the same speed on two different highways?

Click to read more...

 

[Mook]

you sure these just arent like radar images from a loch ness monster search?

 

[pkracing03]

i really dont think that would happen

 

[Bru]

I'm just trying to cover my tracks. It was me, sorry.

 

[Ricky]

i hit close to 130 on my way home from work once i get out of the construction area on 88... so it's not that far fetched.

 

[RebelGTP]

It's a common occurrance and it is true. It is called "Radar Ducting." Temperature inversions in the lower atmosphere can cause the NEXRAD radar beam to refract down onto the Earth's surface and report precipitation where traffic is located or where tall objects are. The windmills along I-39 in Lee and LaSalle Counties are seen on Chicago WSR-88D NEXRAD a lot. Sometimes you can see the Chicago Skyline. Normally the Radar Beam is anywhere from 1300 feet to 2300 feet up in the air (at 5% tilt, the lowest tilt available). The Beam is higer the farther you get away from the radar itself. Here in the Rockford Area, the beam is a mile up.

I know quite a few meteorologists via TheWeatherBoard.com and this oddity is common country-wide. In Cheyenne, WY, the owner of TheWeatherBoard is an Air Force Meteorologist and he says that the Semis driving through the valleys South and Southwest of Cheyenne on I-80 trip the "tornado alert" algorithm in the radar (even in clear weather). I have seen this in my Weather Radar Program myself too...

 

[RebelGTP]

BTW, here is an image I took in my $80 weather radar program. This shows the windmills along I-39 north of Mendota. This was screenshot in 2005 before they built more of those things...

 

[Scgoaty]

I think it's Panda on his vacation trying to mess with my weather forecast.

 

[ChrisRac]

Its probably two people tryin to get to the same places using various routes.

 

[Bru]

Gumballers?