Precipitation and Storms

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Motions of Extratropical Storms

Four (4) varieties of motion occur:



Life Cycle of an Extratropical Storm

1) Smooth frontal surface

  • fronts meet along linear zone of discontinuity
    • two different air masses meet
    • lifting begins along fronts

Satellite Images & Graphics:
2) Cyclonic wave appears
  • bend in jet stream to begin forming wave
    (Rossby Wave)
  • cold front begins to outpace warm front
  • linear squal line forms (intense, heavy precip.)
  • unstable air follows

Satellite Images:

3) Occlusion

  • fronts overlaps in center
  • warm sector increasingly squeezed and displaced
  • finally cold air completely catches up to warm front
  • eventually all air is aloft - no more "buoyancy" or lifting energy
  • storm dissipates

Satellite Images & Graphics:


Development of Extratropical Anti-cyclone (High)

Physical Index