Notes:
This slide shows a time-height diagram of upward vertical motion (yellow contours, upward vertical motion dashed) and EPV (negative values shaded blue), from the NAM run on October 28, 00z. Note that large areas of negative EPV can be seen at mid-levels during the first half of the event, co-located with significant lift. After a large burst of mid-level negative EPV centered around 12z, the negative EPV diminished, disappearing almost completely by 18z.
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