Noticing, that it is gray in Pantone this year, I have questioned myself, is it clear for everyone, what is this color about?
And you know that gray is even not a color - it is achromatic color meaning literally that it is a color "without color" ;)
Is it black with plenty of water? Good try. If you paint a dark illustration or halloween greeting card for your friend :)
Seriously, artists refuse from this method for one reason - black (even with white together) has a masking pigment, and your artwork will be heavy, not clear, not light.
Breath out, I know it's too much for today.
Deal with the fact - there exists a grayish shadow only on your painting, it contrasts with the nearest colors to show IT IS GRAY.
To get this shadow mix opposite colors from the color wheel, and you'll get different grays!
Take colors and play this watercolor game!
In watercolor technique my favourite mix is cobalt blue and quinacridone sienna, which I used for gray this painting.
Have a colorful weekend and do not forget, that the sky will be never gray for you from this day!