FIG. 4: August through October anomaly values of: (a) the vertical shear magnitude (contour interval is 1.5 m s^-1, with weaker (stronger) than average shear values dashed (solid) and shear that is at least 3 m s^-1 weaker than climatology is shaded); (b) the vertical shear vector (contour interval is 2 m s^-1, with values larger than 4 m s^-1 shaded); (c) the 200 mb streamlines and zonal wind speeds (contour interval is 2 m s^-1, with positive (negative) values solid (dashed) and any easterly component greater than 2 m s^-1 is shaded); and (d) the 850 mb streamlines and zonal wind speeds (contour interval is 2 m s^-1, with positive (negative) values solid (dashed) and any westerly component greater than 2 m s^-1 is shaded). Anomalies are departures from the 1979-1995 base period monthly means.