Okay. I found some data on Dec 2, 2005. Plot attached. I remember seeing the lennies on that Friday during lunch hour at work, so I pulled up the sounding data from 20:00 UTC. Clearly, the wind gradient was there, but winds were pretty strong (hard for serious XC?). Wind actually didnít increase much above a certain altitude, it stayed constant. Wave would have been stronger with a higher altitude gradient? Also there was instability below 10-11k MSL in the temperature profile. That seems to be a characteristic of every single GREAT wave day. The wave likes to bounce on top of a layer of unstable air.

Other observations?




I was unable to find the met data for the day in retrospect. But I do recall the winds at 12kft being in the 40 to 60 k range straight west. I feared that it would blow out the wave but clearly not. The wind was blowing 25 to 35 on the ground, so while the wave was good, it had some safety issues. I watched Garret and Mr. Hill from Washington take off in an S10 and attached are photos therefrom. Note the dust being stripped up off the ground by the wind in the distance of the takeoff photo. The lennies in the photos were stacking 3 deep by 9 am.




Excellent report and a great job of logging XC miles. I suspect that under certain circumstances, that is, wind direction and velocity, the relative alignment of the topography cancels out the wave and although there area areas of lift, there are far more areas of sink. This seems to occur more often when the wave is a blue one. Perhaps this only this only seems to be the case since there is little or no moisture to support the development of clouds to mark the existence of lift or the lack there of. If we can find a way to go back and dig up the maps for Friday the 2nd, I think there is much to be learned about what might be an "ideal" day for a wave XC.



-----Original Message-----

Hi All,

Having worked the weekend, I took off yesterday and flew in what I hoped would be good wave. Winds were forecast to be of the right velocities but showing W by NW and annoying near 300 degrees ? which I felt would be beyond the limit of N/S trending landforms to produce wave. And I think that is what happened. As a result only a couple of places produced any lift, and I think the lift correlated to WNW facing landforms especially Oso canyon in the Sandias.

The day was completely blue by the time I launched and the wind as predicted appeared to be around 290 at 30 at 12000. This direction was constant throughout both time and altitude throughout a 4 hour flight, varying less than 4 degrees. (Ain?t SeeYou grand?) Overall the sensation was one of finding lift working it to the top along a seemingly narrow ridge, then charging out into the blue only to find that the sink varied between -6 and -10. Actually I did see some minus 13 on the averager. I understand that this must happen sometimes, but this seemed to me to defy the laws of physics. No matter which direction I went, the sink was pervasive and strong.

The air must have been being exported to China ?cause it was going down fast and coming up rarely. From my little islands of lift, I tried forays North, West, and South all with the same result. At one point I figured the little Rincon between Mosca and Guadalupe Peaks might be cooking some lift SW of Estancia, as it sometimes does. But no, instead I found 10 kt sink and no change in direction would make it better. If I had had time, a foray east from a lift island would have at least been interesting, but duty called.

From this I am inclined to conclude two things. First, clouds are more important for wave days even than for thermal days because the sinking regions of air are stronger so you have less time to hunt. Second, while days like this can be fun and even rack OLC miles, the chance of going far seems limited. The gaps are too large and the sink too strong. I think long distance cross country wave days seem to me to need wind flows perpendicular to the mountain chains ? I suspect it needs to be as close to 270 as possible. I would like to know what your thoughts are regarding this latter conclusion.

As a side note, today looks like the kind of day we are describing. See attached image.

Mike Abernathy