Conditions for fog-filled canyons? Stan?

What conditions may be used to predit when a canyon like the Grand may be filled with fog? I was at the Canyon yesterday and was wondering what I might look for to predict it being filled with fog and being able to photograph above the layer from the rim. Since Flagstaff is only 2 hours away, a quick trip may be likely if conditions are right.

Doug,

You might want to check out the Clear Dark Sky website.

http://www.cleardarksky.com/c/GCNrtAZkey.html?1

Red in the humidity histogram indicates higher humidity and the possibility of fog. Click on it and you will see a high level map of the computer forecast.

Thanks Bill!

Put a homing beacon on my truck. HA! I wish! Fog-filled canyons are on my to-do list, from the Grand to Canyonlands.

Cloudman Todd, be cautious if you see an ugly bearded dog following you in a pick-up truck

I see that when I look in my rear view mirror, Doug!

When looking at the forecast, check both the temperature and the dew point. When they are within a couple of degrees of each other, you'll have fog.

Guy

Well, not always. But moisture is a good thing. Recent (as in, previous or current day) precipitation is a good sign, followed rapidly by building high pressure--a ridge moving in (and clearing conditions) is a signal of warmer air aloft, and that's a good recipe for valley fog because it creates a temperature inversion. The clearing conditions are good especially if they come before sunrise, that allows more radiational cooling, and the colder it gets the faster the fog comes. So, its never a 'given', but look for the post frontal or post rain/snow days.

Thanks all for the info. It'll help me keep me know when to keep tabs on the Canyon. Sedona would be cool that way also.