You spy out a cave a few hundred feet off of the path with the old stones. It is quite roomy and you all can get out of the rain, which with the dark clouds rolling in now, will be falling soon.

Asariel will move ahead of the cart to the cave to try and check if it's empty or occupied. Stealth 13, perception 17)

The cave is empty.

Kaelen ritual casts alarm on the cave entrance to go off with an audible sound if anyone other than the party and kobolds comes through.

You get settled in the cave just as big drops of water begin crashing down from the sky. The wind kicks up, knocking over any loose objects near the mouth of the cave.
Lightning flashes, thunder crashes, and the sky grows quite dark. You begin wondering how long it will keep up this intensity when you hear a terrible scream from the direction of the path.

Perception check to discern details from the scream:
DC 10:

DC 15:

 DC 20:

(Perception 10)

Arista had been crouched just inside the cave mouth, shoulder against the stone, watching the rain sheet down like a gray curtain while she finished cinching the mule-tack beneath the overhang. A sudden, ragged cry knifed through the thunder—definitely a man, and close. She straightens at once, staff tapping the rock, voice carrying over the roar of rainfall: “That was a man’s scream—someone’s in trouble.” She slings her shield onto her forearm, glances at each companion in turn, and nods toward the storm-blotted treeline. “I’m going. Who’s with me?”

Perception: 15

"I heard two male voices," Kaelen states, frowning slightly, "The kobolds have never seen any travelers get this far. It could be a trick to lure us out." He crosses his arms. "But it could also be another 'sacrifice' like at the pillar...If so, perhaps we can save them. Don't rush in until I can sneak ahead and confirm the situation."

[[Perception 11]]

"Two? I could only discern one, but I suspect your ears are keener than mine." Mathias says to Kaelen, while touching the ranger on the shoulder.  "The weather is fierce out there, if you are going out I figured you could use any aid available." the druid says casting a simple cantrip on Kaelen. [[Guidance for Perception]]

As Kaelen heads out, Mathias readies his staff, empowering it with primal energy. [[Shillelagh]]

Arista gives a terse nod. “Scout, then—I’ll shadow you at bow-shot,” she says, adjusting her grip on her staff. “I stay within sixty feet and I can pull you back from the brink if it’s a trap.” Without further delay she steps into the rain behind Kaelen, keeping low and matching his pace, ready to surge forward with healing magic the instant he signals.

(perception 17) "I can confirm there was two male voices there." Asariel gets up quickly and follows Kaelen closely. But not as quietly as he would like as he slips in the rain (stealth 7)

Brekka hears only one the scream, but he's not one to argue with his more perceptive companions. He just gets to business. The shield emblazoned with an eye is strapped to his arm while he hefts his longsword in the other.

"Lead the way. I'll hang back. Just make sure you yell loud enough if you find trouble!"

Kaelen raises his hood and moves ahead of the others out into the darkness, heading in the direction the screams seemed to be coming from.

Stealth: 22, Perception: 22+1 guidance= 23

Kaelen's effective vision range is reduced due to the weather, but he is able to see what has transpired. Two travelers, coming from the keep have been attacked and slain.

Four avian, mostly, predators have apparently slain them and are consuming them, seemingly concentrating on their chests. The creatures have the bodies of eagles the size of a man, but the heads of fanged stags.

They have not noticed you.

Kaelen returns to the others and reports what he saw, including a description of the unnerving monsters. "They're already dead, but we might be able to find something useful on their bodies. What do you think?"

"Honestly, it sounds like they are eating and then will leave. We will probably be able to get any information without fighting just by waiting. But if we can get the surprise on them and take them out, it's one less threat to try and surprise us later on."

Asariel has no objections either way, he's just laying out the options he sees for the others to decide. 

Arista tightens the strap on her shield and nods to Kaelen and Asariel. “If they’re beyond saving, I say we let the carrion finish and move in once the storm slackens—less risk of a blind fight in this downpour.” She glances back toward Arglen and the others, jerking her chin toward the rain-blurred treeline. “You dragon-folk range these hills: ever see great eagle-bodies with stag heads and fangs? Tell us what we’re dealing with while we wait.”

"There is more than one Peryton? That's a bad omen. They usually leave kobolds alone, we should go perform a ritual to ward them off the cave." She pulls out a little yew wand with a bird skull attached to it and heads for the opening of the cave.

Kaelen, I'd like a Survival check or a Stealth check with disadvantage.

Kaelen stealth with disadvantage: 10

Kaelen: Perception check [Flat - Technically you have advantage, but the storm is giving disadvantage]

Everyone else: Perception check [disadvantage]

After about a half an hour the storm slackens to a light rain, but the air is more comfortable.