Long Description:

Eta 12-hr 500 mb heights and 290 K local pressure derivative valid 1/28 00z.

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Speaker Notes:

Recall, however that to diagnose the total large-scale upward motion, you also need to consider the local pressure derivative. In this case, the negative of the local pressure derivative is positive, indicating upward motion (the mid-level wave is approaching). Another way of looking at this would be to say that warm advection is weak to negative across the area at 00z on the 28th, but vorticity advection is strongly positive.