Dissipating stage
Figure on left taken from Mesoscale Meteorology and Forecasting (pub. Peter S. Ray (1986)) and originally published by Byers and Braham (1949)
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| The final stage of a thunderstorm is the dissipating stage. Out
this point, the downdraft is dominating the storm and has cutoff the
warm moist inflow. This causes the storm to lose energy and it
begins to dissipate. For an ordinary thunderstorms, this stage is
reached approximately 30 minutes after the towering cumulus stage.
Notice that the cold outflow of the storm extends away from the storm and is relatively shallow. With such a shallow outflow boundary, the warm and moist air cannot be lifted enough to produce a towering cumulus cloud and initiate another thunderstorms. On radar, the storm in its dissipating stage will have the highest reflectivity at low levels with weak returns at mid-levels. Although not shown, an outflow boundary may also show up at the lowest levels moving away from the storm. This indicates that the storms updraft has weakened and cannot support hail nor is it feeding enough moisture into the storm to continue to produce heavy precipitation. In several minutes, no returns will be seen from this storm and only a few high clouds will remain. |
