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.
Focus shifted to California for the Western US readings, but the strongest is out east.
The Eastern USA now has a 9.1 Magnitude frequency, a highly rare event. Keep in mind this has been building in longwave form for about a week now.
Do feel it was the signal that was foreseeing the destruction of what is Hurricane Sandy.
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