Clear Skies Before the Storm

We're expecting 2-3 inches of snow tomorrow, but tonight the sky is crystal clear for a few more minutes. Both images were taken on a Nikon D750 using the Tamron SP 150-600MM F/5-6.3 Di VC USD with a Tamron 2X teleconvertor for an equivalent magnification of 1200mm. The first image below is a a composite of 9 images, stacked in Registak 6.0

Waxing Crescent Moon - 04 Jan 2017 18:51:00 EST Nikon D750  ISO 320 1200mm f/10 1/160 sec. 9-image stack using Registak 6.0

Below is the lead single-frame image. Can you see a difference? 

Waxing Crescent Moon - 04 Jan 2017 18:51:00 EST Nikon D750  ISO 320 1200mm f/10 1/100 sec.