FIG. 11. Interaction-relative composite analyses for (a),(c),(e) strong (N5 54) and (b),(d),(f) weak (N5 54) TC– extratropical flow interactions at the time of maximum interaction. Analyses show 250–150-hPa layer-averaged PV advection (shaded according to color bar, PVUday21), PV (contours, every 2 PVU), and wind (vectors, m s21). The TC symbol denotes the composite TC position. In (a),(b) the total and (c),(d) the nondivergent wind are used to compute PV advection and are plotted for values .18m s21, whereas in (e),(f), the irrotational wind is used to compute PV advection and is plotted for values .2m s21.
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