The mean horizontal age strophic wind speed within an atmospheric column extending from 300 hPa to 250 hPa increases from 1.5 knots to 3.5 knots over a distance of 75 kilometer to the east. At all other levels the age strophic wind speed is zero. Assuming an equivalent bar tropic environment at all levels with no thermodynamic forcing, Determine what is the estimated vertical velocity at 300 hPa?