Move the areas of 24-hour height rises and falls at the speed of the short waves, and note at several key points the amount and direction of the height change from the current chart. Adjust the advected height changes, and, in turn, adjust these for positions of the long waves, pressure systems, and short waves. When the contributions from advection and time differentials are not in agreement with convergence and divergence, adjust the contribution of each and use accordingly. Adjust the height values to the forecasted intensities of the systems. One factor washes away the contribution made by another, and the system remains at or near its present state of intensity. .
All factors point toward weakening of the system.
Sketch the preliminary contours, connecting the forecast positions of the long waves, short waves, and the pressure systems with the values determined by steps 1 through 5 above. The chart should follow continuity from the existing pattern. . The chart should be vertically consistent and rational in the horizontal. . The chart should not deviate from the seasonal pattern unless substantiated beyond a doubt. . Unless indicators dictate otherwise, it should follow the normal patterns.