The simplicity of the round hills and easy access makes for some great options in most any weather situation. Yet it is easy to overlook some more complex scenarios that may exist.
First and foremost is the LCR inversion.
The top of Sheba Crater is the same elevation as the 2 Bar 3, 6400 ft. the resturant/bar you passed on your way to the hill. The top of Merriam is 6800 ft. close to the average elevation of Flagstaff. If you continued out Leupp rd you would come to the town of Leupp which is a historic crossing point of the little Colorado River which lies at 4700 ft. From this point the road begins to climb up to the mesa's and mountains of the Hopi and Navajo reservations making for a 2300 ft. deep valley that gets deeper as it nears the Grand Canyon. Most nights this valley is filled with cool air and a thick inversion forms. The inversion usually builds up beyond the top of each hill each night. To better understand what is going on the locals look at the Winslow Skew-T to get an idea of what is going on in the LCR. We still look at the winds aloft in Flagstaff but the Winslow data usually shows us the inversion a little more clearly.
If it is a standard high pressure day with light winds aloft you'll find that the day will start out L&V and as the day progresses become more northerly, even if there are light winds aloft from another direction.
If there are strong winds aloft and you get to the hill to find light winds on the surface plan on calling it quits before the inversion breaks. When you start to see a light base flow become still and conditions become switchy the locals have learned this is a warning shot over the bow and you should go home to the wife even though it is your one day to fly.
Ground clearance mid-day.
For the aspiring p-3 or the hungry p-4 this has seemed to hurt more people at the Craters than any other issue I can recall. When thermalling mid-day remember you are not ridge soaring and the closer to the hill you are the smaller the thermals are as you are flying into the base of them. The best pilots at the Craters watch the cycle's cafefully, launch at the end of a lull and fly into the top of the thermals that have traveled up the valley and will be releasing from the top of the hill. They often pass up thermals near launch to get out away from the hill and into a more usable peace of lift. All too often we have had to call the rescue helicopter for the pilot that was scratching near the hill and left their own crater in the Craters.
