Strange radar echoes

[Gabou971]

I was tracking hurricane mickael over the USA and noticed strange cloud shapes over the country. I crosschecked with aviation website providing radar imagery for the USA and those clouds were not there. Very strange! Look at the picture, you can see the dying hurricane on the right and those "fake clouds with an eye in the middle" all over the USA:

Is someone playing with the radar data? Or trying to create fake hurricanes echoes ahaha

[Gkikas LGPZ]

@gabou971
The same "fake echoes" on the original imagery of National Weather Service

Those echoes in the immediate area of the radar are "ground clutters".

According to https://www.weather.gov/jetstream/radarfaq#everything
(General questions, No. 2)
" Though surface echoes appear in the base and composite reflectivity images, special automated error checking generally removes their effects from precipitation accumulation products. The national reflectivity mosaic product is also automatically edited to detect and remove most non-precipitation features. ".

You say: "I crosschecked with aviation website providing radar imagery for the USA and those clouds were not there."

It seems that this website is filtering ground clutters.

[Gkikas LGPZ]

Same image, filter off - filter on.

[Gabou971]

Ahhh interesting. I thought ground clutter was removed during radar calibration or something. Is there a way to have automatic ground clutter filter on Windy ?

It is strange that it's not a constant problem though, because now it's gone, even on Windy. I wonder if temperature, moisture or other phenomenom can increase the ground clutter.

EDIT:

Well, it's well explained with also other info on the website you provided, thanks.

"Under highly stable atmospheric conditions (typically on calm, clear nights), the radar beam can be refracted almost directly into the ground at some distance from the radar, resulting in an area of intense-looking echoes."