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.