Wavelengths -
Shortwaves indicate near events, a high short spike usually means a short term major event is about to happen in that area.
Longwaves and steady increases usually mean a large scale change is developing in the area that will effect a large area's upper level jet stream.

M1 - M2 - Slight change is expected, but overall the weather pattern is not being affected.

M3 - M5 - Change is expected and the reading indicates between then and and a few days it will happen. This is considered a moderate reading, which if a short spike can be a nearby event such as severe weather, unexpected lightning, or a tornado.

M6 - M9 - Significant change is expected. Anything over M7 is rare and special attention must be directed when readings go seven and higher. Severe storms are associated with this reading, which if a short spike can be a nearby event and a long duration and slow build being a large scale change.

M10 - Associated with tornado outbreaks. This also can be strong hurricanes and blizzards