Not sure what formula is right as some times the Cd ratio is included and other times it is not. Here is a quote and a link to a page that discusses it and presents the formulas for different wind loading on flats rounds etc on an antenna tower.
http://www.arraysolutions.com/Products/windloads.htm
The Generic Formula
For using the actual sustained wind speed expected (were we to actually determine it) :
Force, F = A x P x Cd
A = The projected area of the item
P , Wind pressure (Psf), = .00256 x V^2 (V= wind speed in Mph)
Cd , Drag coefficient, = 2.0 for flat plates. For a long cylinder (like most antenna tubes), Cd = 1.2.
Note the relationship between them is 1.2/2 = .6, not quite 2/3.
Hope this next link muddies the water even more. It seems there are two formulas floating out there and many use this next formula which is from Bernoulli.
http://mohandes.net/eng/lds/index.php?pg=wloads
The cart below taken from a link on the above website would seem to go with DanB and gives about half of the psf of the chart posted in an earlier post.
Wind Stagnation Pressure (qs) at Standard Height of 33 Feet
Basic Wind Speed (mph)1 (X 1.61 for km/hr) 70 80 90 100 110 120 130
Pressure qs (psf) (X 0.0479 for kN/m2) 12.6 16.4 20.8 25.6 31.0 36.9 43.3
Does the main formula from Bernoulli take into account the drag (reduced air pressure)seen behind the object or just the air pressure on the front?
Finis