Refer to figure.
London to Munich: The CAT area (1) is North of our planned routing. Additionally, it would only affect flights between FL310 and FL420 => we are planning to fly at FL210 (check "CAT AREAS" legend on the left corner of the chart).
Keflavik to Oslo: CAT area 3, which could possibly affect our flight (between FL190 and FL410), is situated south of our route and, therefore, will not affect us.
Madrid to Lisbon: There is a CAT area (4) covering most of this flight. However, it only affects flights between FL230 and FL340 => which means we will be flying right under it and will not experience CAT.

• OSLO - PARIS: As you can see in the graph, the flight between Oslo and Paris crosses 2 CAT areas: CAT area 1 and 3. CAT area 1 does not affect our flight because it's lower limit is FL310 and we will be flying at FL210. However, CAT area 3 (occuring between FL190 and FL410) will affect us. For that reason, we might experience moderate CAT at FL210.