Inside chrome editor, under !advanced attributes!, click on !map settings! button.
Then open the !sky! settings field and change the time settings in the textboxes under H,M,S(=Hours,Minutes,Seconds).
To have the sun at the top, it's H=0, M=12, S=0,
or it is H=12, M=0, and S=0.

(If you deleted the weather script, you still can change the sun direction in map settings under varlist field type 0, 12,0 in the sun direction settings to put the sun at the top.)

You can move the sun where you want with the varlist settings.

Now if you restart chromed and your custom sun or weather settings are back to the default settings,
you'll have to disable or delete the weather script.

To disable the weather script, look in this tutorial under Environment:
But sometimes, this method will mess up with the weather settings.

The other way to enable varlist weather changes is to delete the weather script manually.
To do this,open your source map folder then delete the map weather.scr file and you'll be able to change varlist settings by yours.

One thing is that the weather.scr seems to be a dynamic weather script, it means that the weather is changing during the daytime but i'd not tested if coj2 supports the dynamic daytime.
I never seen any weather change while i was playing in coj 2.
All i know is that dead island and coj the cartel supports the dynamic daytime script.
I guess coj 2 was'nt finished enough to support this nice feature.
I'll test further but there's so many things to set in chromed that i forget the half part of interesting things...

One more thing, if you plan to add rain into any new map, you'll have to put the sun at the top because the raindrop's fx were build
with the sun at the top.