Does anybody know what the icon inside the circle mean ?
Found at aviationweather.gov
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It seems to be the symbol "M" for "missing cloud information". Note that CWIJ has a circle for cloud coverage that is slightly bigger than the standard circle size used for most other airports.
Southeast of CWIJ, there is CWIC which has the symbol M as well, but there the edge of the circle coincides with the lower part of the symbol shown in the CWIJ circle.
There is another station towards the east (CYBK) that has a bigger circle as well, and it has a 6/8 cloud coverage symbol that does not fully fill the circle. For comparison, PAUM has a standard circle size with the same 6/8 cloud coverage symbol filling all the way to the circle's edge.
This leads me to believe that the software behind aviationweather.gov has a symbol library which includes cloud coverage symbols designed for a certain standard circle size. Some airport are represent by a circle which is bigger than the standard, and this leads to the strange representation of the symbol 'M' seen at CWIJ.