GFS pressure, wind and adiabatic omega on the 300 K isentropic surface

isentropic lift

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This slide indicates that the GFS was forecasting near neutral pressure advection across central New York on the 300 K isentropic surface (as opposed to positive advection by the NAM). Note that the flow at this level (near 500 mb) is forecast to be southerly, as opposed to southeasterly on the NAM forecast. Note also that some upward motion is still being indicated, as the northeastward movement of the upper-level wave over the central Appalachian Mountains is producing a negative local pressure tendency, which is resulting in a negative (upward) total pressure tendency (upward motion).

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