What is going on with US weather radar today? | Hacker News Reader

What is going on with US weather radar today?

atlas.niu.edu

19 pointsJimmc41414 comments

Here's the loop from today

https://atlas.niu.edu/analysis/radar/midwest/midwest_radar_b...

The NEXRAD weather radar system has multiple modes of operation (Volumetric Coverage Patterns) configurable for each antenna site. Each of these is optimized for different weather conditions. The light-blue returns represent humidity in the air (not quite rain or fog) and is usually tuned below the “noise floor”.

Current operating modes: https://www.roc.noaa.gov/branches/operations-branch/current-...

I haven't seen enough history to know if that's normal or not, but I can tell you that the center of each of those blue "clouds" is a nexrad radar station. It's view is a wide cone from the ground upwards (technically a set of cones from each of the radar's tilt angles).

It's quite possible there is some lower altitude fog/precipitation/something that is only visible to the radar at it's lower tilt angles. But that's just speculation.

One of my weird hobbies is radar chasing storms, and all of that stuff is completely normal. NEXRAD is very sensitive, especially when it's in clear air mode (it has different modes depending on if it's raining in the area) and can pick up things like dust, birds, bats, and insects. There's also ground clutter from things like buildings, wind farms, and even cars.

The National Weather Service has a good brief explainer: https://www.weather.gov/iwx/wsr_88d

They also have an interesting PDF covering some of the more unique signatures you might see, though it's not exhaustive: https://www.weather.gov/media/btv/research/Radar%20Artifacts...

Does clear air mode pick up wildfire smoke? There has been an awful lot of that lately over the US from Canada and the West Coast.

These are base reflectivity images. Composite reflectivity products reduce the noise from around the radar stations. The old NWS Java site used to let you select between them. Raw base images seem to be unavailable on the modern moving maps.

https://www.wunderground.com/wundermap?lat=44.059&lon=-121.3... - I don't see that artifact or whatever it is on this radar view...

I just wish we even had a radar where I live.

Looks normal to me, for a poorly filtered NEXRAD mosaic anyway. What's the issue?

Commenter is either:

(a) early in their radar-watching journey, and starting to notice the finer details in radar products, or;

(b) looking to stir unfounded panic by exaggerating a pattern that’s filtered out or not noticed by others, in light of current events.

Unlike the NEXRAD images in question, the noise floor on the Internet this is quite high and hard to differentiate between the two.

Or they had a good faith question about an unfamiliar phenomenon.

I wouldn’t say I was on a radar watching journey nor did I exaggerate any details.

I have an idea. If you have a question, just ask a question. Otherwise we have to guess at what your question is.

I assumed good faith, I just don't know what part of the image you're referring to. Feel free to tell us :)

That’s a fair point.

The line between concern (GUYS WEATHER RADAR IS SHOWING END TIMES) and curiosity (check out this neat radar image I saw) can be pretty thin in technical spaces.

Creative minds in the community are very good at filling in the blanks, no matter the accuracy.

Radars uniformly set on high sensitivity. You're looking at the noise floor within [x] miles of the radar. The sudden smaller size of a couple was a manual dbm adjustment. They seem more common these days, I think because when you saw sharp cutoffs it was usually a threshold cutoff setting some human had to twiddle and humans don't bother anymore. This stuff drives some Boomers crazy and sets them to babbling about HAARP, especially the pacman shapes that represent a metallic obstruction near the center of the radar.

Insects?

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