I successfully climbed Lightning Peak via Great Western Trail on Nov 3, 2019. Based on my experience, I would revise the route description as follows:
From the GWT parking area, pass the gate at the west end of the parking lot. Walk up the small dirt road for .8 miles, and before you get to the second gate take a left onto a smaller hiking trail. There is no sign at the beginning of the trail. But it is easy to figure it out. The trail splits soon after the beginning. Take the left one. Follow the trail for another 3.5 miles (This distance may be from the trailhead). There is a junction where you need to take the left fork toward Windy Pass. There is no sign at the junction but is a rock in the middle. After another 2 miles you are on top of the pass. There is a sign of the trail number at the pass but no sign of Windy Pass. Turn right (west) and try to stay on the ridgeline (do not go down).
Via the Great Western Trail. About 1/4 mile before Windy Pass where the GWT makes a right angle bend, we took off for the ridge up some steep snow. From the top we went down to Windy Pass, mostly on snow, climbed Point 9474 on the other side of the pass, and then took the GWT back to the start.
I've wanted to climb Lightning peak since 2007 when I first noticed it on a map. I made my first attempt December 2009, on snowshoes, but when I got knocked down by an alvanche I decided to turn around. This spring I got rained out.
August 13, 2010 I rode, and mostly pushed, my bike up the GWT from the Telford ranch parking area 3.5 miles to the sign that points to Windy Pass 2.0 miles. I hiked up to Windy Pass, and unsuccessfully tried to find water. Then I bush whacked up the east ridge to the peak. On the peak I found a cartridge box housing a summit registry which I signed. I forgot my camera, and so I don't know how long it took to summit, but I'd guess 4 hours. Round trip was 6.5 hours (car to car).
We took the GWT and then pealed off at about the 3 mile mark and directly ascended the mile long bowl on the East side of the peak rather than go all the way to Windy Pass. This was long and steep but a far superior route. The views at the summit are the best in the Wasatch with a 360 degree panoroma of Shingle Mill Peak, Freedom Peak, Provo Peak, Nebo, Loafer, Spanish Fork Peak, the High Uintas, Little Cottonwood Peaks, Timp, and Cascade. The slide down was awesome. Much better on snow than in the summer.
Can't say I'd really recommend this hike. It's a dry, hot one. My dog got sick, I think due to dehydration, and threw up a lot on the way down and in my car on the way home.
I ran into so much brush from the saddle to the top of the peak that I nearly gave up several times. Perhaps if people are better at finding trails than me, an easier way can be found.
This hike is amazing, the views from the top are spectacular. I definitely want to do this hike again in the winter. Watch out for horse poop.