The Highline Trailhead is located along State Highway 150 33.2 miles east and north of Kamas, or you could drive south from Evanston. You could also start at Mirror Lake, but you must pay to park there, and there isn't as much room to park.
Blue = Final section of the Rock Creek-South Face Route.
This is the easiest route to the summit of Priord Peak, but it is a longer hike than the other routes.
From the trailhead at 10,347 feet, follow the Highline Trail .8 miles to the junction with the Mirror Lake Trail. The trail continues south and east and drops to 9900 feet. Scudder Lake is passed after 2.2 miles (from the trailhead). After another .8 miles, pass a junction with the Wilder Lake Trail. Stay left on the Highline Trail. After another 1.3 miles, stay right at the junction where the Naturalist Basin Trail branches left.
Continue on the Highline Trail towards Rocky Sea Pass, passing the junctions with the Pinto Lake Trail after 1.5 miles and the 4-Lakes Basin Trail after another 1.2 miles. Rocky Sea Pass is another 1.2 miles along a steady up hill grade. The pass is 8.2 miles from the trailhead. Enjoy the spectacular views.
Continue east and down the steep east side of the pass for 1.9 miles to a junction. Leave the Highline trail here, turning left on the head of Rock Creek Trail. After another mile, take a right at the junction with the Lightning Lake Trail. The lake is another mile beyond. This trail isn't shown on the topo map, but is in good condition. There are two other forks, and take a left at each one. Along the way you will jump a deep, but narrow and small fish filled stream before the trail climbs to Lightning Lake which makes a good basecamp to explore the area and climb the nearby peaks (the best campsite is on the south side of the lake). A nice waterfall is not too far east of the lake. There are actually many, many lakes in the area and you can always find a fairly large lake to have all to yourself and all are filled with trout as well.
From the north end of Lightning Lake, follow the Head of Rock Creek Trail east and past Helen Lake. At any location between Helen Lake and the stream crossing just to the east, you can scramble up the steep slope to the north and to the summit of Priord Peak. There is much boulder-hopping and the route is steep, but this is still the easiest route to the summit. You will enjoy a fantastic view from the summit.
This route is 27 miles round trip and usually takes three days, but many days or weeks can be spent exploring the area and climbing the peaks along the way as this is some real wilderness country surrounded by countless peaks and lakes.
Note: For a really great side trip, climb to the pass located to the NW of Helen and Lightning Lakes. This is West Ostler Pass. The views straight down on Amethyst Lake are incredible.
The south face of Priord Peak is the left side of this photo of the peak as taken from "South Yard Peak".
A good pair of boots is needed. Rocky Sea Pass often requires an ice axe before mid-July.