The next task is to ensure that the sky is cloudless for the festivities, so that everypony has a clear view of the morning sky. Like all other weather conditions, this is managed by local pegasi. A pegasus named Rainbow Dash is head of the Ponyville weather team, and wherever she is, whatever she's doing, the sky is not clear. Twilight, despite all her magical prowess, is grounded, so she's reduced to simply wandering around with her head turned to the sky. She quickly realizes that's no way to find somepony, so she musters the resolve to ask the first pegasi she meets—on the ground. Celestia's counting on her. She tells Spike, who seems excited at the prospect of Twilight initiating a conversation.
So when she encounters a gray-coated, platinum blond-maned mare eating a muffin on a cafe patio, she swallows and approaches. Walks up and starts talking, just like that. "Excuse me, do you have a second?"
The pegasus finds it necessary to introduce herself: "Oh, sure! I'm Derpy Hooves! Who're you two?" Her voice is considerably more sultry than Twilight had expected, but nevertheless she can sense the cheer and good will oozing out of her mouth. Like she's never met a unicorn before.
"I'm Twilight Sparkle, emissary of Princess Celestia. I'm overseeing festival preparations," says Twilight. "And this is my assistant, Spike."
Derpy motions to shake Twilight's hoof, but forgets there's a table in the way. She jostles the table, knocking off a set of unused silverware on the other side. The clatter seems to startle her, as she begins to rear up on her hind legs, but there hasn't stopped being a table in the way. This time the empty plate is close enough to the edge to fall, but this time, Twilight is poised to catch it.
"Oh, sweet catch! Sorry about that. But it's great to meet you! Take a seat! Would one of you like the other muffin?" she asks. You don't see that in Canterlot.
Twilight, reluctant to inspire Derpy to further motion and in general wary of accepting gifts, pointedly would not like the other muffin. She'll never understand how other ponies do it. How do you show your gratitude? How much do you reimburse? Too much of a puzzle, or at least not the right kind. "No, thank you."
Spike hops up onto the spare chair and takes the second muffin from Derpy's hoof. "Thanks, Derpy!"
Some ponies have figured it out. Twilight asks, "Are you on the weather team, by chance?"
Derpy says, "Oh, sure! I mostly just deliver mail, but I can help out in a pinch. Why?"
So are you on the team or aren't you?, Twilight thinks. "Have you seen a pony named Rainbow Dash today? The clouds need to have been cleared for the Summer Sun Celebration tomorrow, but it almost looks like rain."
"Oh, no, not today I haven't. Have you checked by the lake near the schoolhouse? I see her relaxing there all the time. Make sure to check on top of the clouds, she might be napping," Derpy says, embedding the remnants of the muffin in her mouth. Spike almost beats her—almost.
That brings the conversation to a natural close. Twilight feels a dirty mixture of independence and indulgence; she has all there is to get, but has nothing to give. As the silence presses down, she starts fidgeting with closings in her mind, trying them on one by one.
"So what do you like to do, Twilight?"
"Uh." Uh. "I, um, I read a lot." Don't scrounge for the scalpel, just get out the sledge. "I'm really in a hurry, so... Thanks for the advice, Derpy." Twilight starts walking away.
Spike hops off the chair and follows her, saying, "See ya later!"
Derpy stops licking the crumbs off her plate long enough to wave goodbye. "Oh, see you later!" she says, wet bits of muffin spewing out.
Pegasi, being largely unenthused with gravity, rarely deign to take naps on the ground when they could doze on much fluffier clouds. So it's no surprise when Twilight spots the head of a supine pony atop a cumulus, above the center of the lake. It's almost certainly Rainbow Dash, assuming her parents took a glance at her hair before naming her. What does surprise Twilight, however, is that Rainbow Dash is neglecting a crucially important task to do literally nothing instead.
"Hello? Are you Rainbow Dash?" she calls out. But her voice isn't carrying well enough to wake up the sleeping pegasus; the lake is fairly wide, and so half the lake is too. "Hellooo?" Nothing.
"It looks like she's out, Twilight," Spike says, helpfully. "Can you do something with your magic?"
Why yes, Spike, I can. She reaches out for her magic, and picks up a stone. She pulls it back, imagining an oversized slingshot strained to its snapping point—and stops. There's surely a less confrontational way to do this. She needs something less physical; it wouldn't do to agitate somepony so critical to the Celebration. How do normal ponies wake somepony up, without rocks? Spike looks at her, expectantly.
It's nontrivial to get any certain timber or tone out of a sonic illusion; ponies make careers out of it. Twilight's spent some time training her visual illusion skills, so she's moved beyond colors and shapes, but she's never devoted any time to sound. She has read Thunderclap's seminal treatise, though: she knows that for any precision, you need quantitative spectrographic data, but she thinks she can pull off a crude cymbal crash offhoof. Percussion should be comparably easier than a string instrument, she thinks; it's just things banging together, right? And so her mind fills with the conception of cymbals' sound, like it's the only sensory input she's ever known, the grassy lakeside fading into darkness, all but the noise slipping away...
As her horn's pink glow infringes on the crown of her vision, she hears the mess she's made. The cacophony indeed sounds like cymbals—maybe a couple hundred pairs of them at once, along with snares, hi-hats, toms, and a platoon of basses, all playing a brutal polyrhythm. Twilight doesn't even want to imagine what a trainwreck the Fourihay decomposition would look like. Know your limits, Twilight. She entertains the thought of making a run for it, but thinks of the Princess. Instead, she just gulps, and contemplates whether she should hope Rainbow Dash woke up or not.
It doesn't matter—Twilight sees Rainbow Dash's limbs flail, but the startled pegasus quickly composes herself. She turns onto her stomach and dangles her forehooves off the edge of her cloud. "Hey! What the buck didja do that for?" she yells, voice cracking.
"I'm sorry! I really need to speak to you. I didn't know that would sound so... grating," Twilight says, fighting not to paw the ground.
"Couldn't you just toss a rock at me or something? What are you doing here, anyway?" asks Rainbow Dash.
"I'm in charge of festival preparations for tomorrow." Twilight blinks, and Rainbow dash is standing before her, throwing her a suspicious side-eye. The rainbow lightning strike on her flank almost declares its own indignation.
"You sure? Because I've never seen you around before..."
Twilight feels a private relief at meeting a pony not so blindly trusting, although it's not making anything easier for her. "That's because I've never been here before. I'm Twilight Sparkle, and I live in Canterlot. This is my assistant, Spike." She pulls him out of the nearby bush he's cowering in. "We're here by order of Princess Celestia." Rainbow Dash leans back out of her personal space, and Twilight lets herself breathe out.
"Okay, I guess," Rainbow Dash says, "but couldn't you think of something smarter?"
Twilight should have run away. "I..."
"Sorry, I guess that's pretty mean of me." She leans back a little more, ears drooping a little. "I'm Rainbow Dash, by the way, but I guess you knew that. You can call me Dash. Or Rainbow, I guess."
Spike nudges Twilight. She feels the ground beneath shift a bit more towards level, and so she extends her hoof. "Glad to meet you, Dash." She is; there's still plenty to do. Should she bring up the weather yet, or—
"You too. So, anyway... why were you looking for me?"
You haven't figured it out? "I wanted to ask about all the clouds, since, as you know, the Summer Sun Celebration starts tonight..."
"Oh, right. Yeah, I just haven't gotten around to it yet," Dash says.
"I see. Uh, well, it's important to get it done sooner rather than later, so..."
"Yeah, I get it. I'll do it after my nap," she says, now trotting towards the lakeside.
"If you insist on napping, can't you ask the team to get started first?"
Rainbow's left ear twitches, and she turns back around. "I'm just gonna do it myself."
No you're not. "Is cloudbursting for the whole town really a one-pony job?"
Something connects in Rainbow Dash's head; she realizes what's missing: Twilight doesn't know who she is. Not really. "Of course not! Unless that pony is Rainbow Dash!"
Twilight's patience is swirling around the drain, any second to bottom out. "Prove it!" she finds herself saying.
"You got it!" And just like that, she's in the sky, kicking clouds out of existence. She starts with her disowned napping spot. Twilight feels a twinge of loss, for forsaken things, but then it's gone.
Spike says, "I guess we just leave her to it?"
"...I guess so. We'll keep in eye on the cloud cover and come back later if we need to," says Twilight, as she walks away.