Prog Charts

[aloft]

Anyone know what the little yellow tick marks across the fronts over WV and offshore of NorCal are?

http://aviationweather.gov/data/products/swl/ll_12_2_cl_new.gif

 

[Alchemy]

From AC 00-45E

[ QUOTE ]
Two short lines across a front indicate a change in classification

[/ QUOTE ]

Basically, its the point where the type, intensity, and/or character of front the changes. This quote was taken from a section about surface analysis charts, but the same publication states that "Fronts used (on prog charts) are the standard symbols and three digit characterization code used on the surface analysis chart."