Erik, don't take this the wrong way but that jpeg I linked to I opened in Photoshop and applied +20 Sat in Hue/Sat and it really made the sun's affect pop on just the green hill highlights with a luminance increase that complimented the soft fog portions of the distant background. I don't know if its my calibrated sRGB gamut display that's making it look chalky & subdued or if that was your intended look.
I'm guessing the subdued hill highlights are from the sun going behind the cloud which I'm assuming you're trying to portray.