1 - It's a beautiful day. The sun is shining, the sky is blue, the clouds are puffy and white, and everything is as nice as nice can be. In the middle of the panel would be Rainbow Dash's house (which I guess is a floating cloud castle with rainbows?).
2 - Same as panel 1, except the weather is starting to turn. The sun and sky darkens and the clouds are turning stormy.
3 - Same as panel 2, except the weather has completely turned. The day is stormy and windy and awful as awful can be.
4 - Interior shot. Rainbow Dash looks down at a handwritten note, crying. Her tears fall onto the page. The note reads (in handwritten writing):
We came by to invite you for a picnic at Puffy Puff Park, but since we couldn't find you, we decided to go without you. Hope you're getting up to some fun stuff on your own!
- The Gang