Look at winds speeds at 250 mb and below (10.5 km). If wind speeds are 20.5 meters per second (m/s) (40 knots) or less there is a better chance for good seeing. If speeds are around 30.8 m/s or higher the seeing is poor. When the jet stream is overhead wind speeds can be over 100 knots.
Image from http://www.profiler.noaa.gov/jsp/profiler.jsp
An alternate site is: http://www.rap.ucar.edu/weather/upper/plt_wp.gif
From Kevin Brose, fellow FRAC member.
1) The maximum wind speed at any level is less than 50 knotsBack to my page | NCAS | January 19, 2006
The 250mb wind speed is usually close to the maximum.
http://laps.fsl.noaa.gov/cgi/laps/domains/co/laps_anl_co_liw_latest.cgi
2) There is no convection occurring (especially if the lifted index > 0)
The CAPE is positive and may exceed 1000 J/K when the L.I. is < 0.
http://laps.fsl.noaa.gov/cgi/laps/domains/co/laps_anl_co_pbe_latest.cgi
3) There are upslope winds at low-levels
http://laps.fsl.noaa.gov/cgi/laps/domains/co/laps_anl_co_wd0_latest.cgi
Here is a turbulence model .