Creating a chart with critical zones

E.g., if you have data like this:

To create the chart with broken data, do the following:

   1.   Add additional data for this chart - in this example:

• column E  to show data before broken line
• column F  to show data after broken data
• column G  to show the biggest data
• column H  for the broken line.

   2.   Select all necessary data - in this example, C5:C14, E5:H14.

   3.   On the Insert tab, in the Charts group, select launch or click on the Recommended Charts button:

   4.   In the Insert Chart dialog box, on the All Charts tab, select the Combo group and then choose Custom Combination:

• For all series, choose Scatter with Smooth Line chart type
• For Series3 and Series4, check Secondary Axis:

   5.   Double-click in the primary vertical axis, and then in the Format Axis task pane, make all changes you prefer for this series. For this example:

   6.   Double-click in the secondary vertical axis, and then in the Format Axis task pane, make all changes you prefer for this series. For this example:

   7.   To hide parts of the lines, select the part of the line, and choose Gradient Fill for it:

   8.   Make adjustments for Vertical Axes; do one of the following:

• To show both Axes, hide non-used data - see more how to hide points on the chart axis:
  
• To hide values of both Axes, on the Format Axis task pane, on the Axis Options tab, in the Labels group, for Label Position choose None for every axis:
  

  Instead of hidden values, you can add a text box to the data you want.

Make any other adjustments to get the look you desire.

See also this tip in French: Comment démontrer les zones critiques du graphique.