(a)	(b)
(c)	(d)
Figure 2. 500 mb height (m) and absolute vorticity (shaded, 10^-5 s^-1) on 4 Jan at (a) 0000UTC, (b) 0600 UTC, (c) 1200 UTC, (d) 1800 UTC. Output is from the Eta model run of 1200 UTC 3 Jan.