The approach employed has been to plot on maps sector vectors and vector resultants that express the directional trends of migration in the eastern United States and the Gulf region, and to compare the data on these maps with data supplied by the U.S. Weather Bureau regarding the directions and velocities of the winds, the location of high and low pressure areas, the movement of cold and warm fronts, and the disposition of isobars or lines of equal pressure.
"A Quantitative Study of the Nocturnal Migration of Birds. Vol.3 No.2"
George H. Lowery.
One of the maps shows the actual isobars as they were recorded by the Weather Bureau.
"The Right Time"
Walter Bupp
The other moving map is the same isobars as predicted by you, Pheola.
"The Right Time"
Walter Bupp