The relationship of anomalously-strong transports of water vapor from the subtropics to cyclogenesis and significant precipitation in extratropical and arctic latitudes has been demonstrated. The transports are due to a combination of planetry-scale and synoptic-scale (individual storm scale) flows. The former may be interpreted as a combination of Peixoto and Ort's mean meridional flow and the contribution from the mean stationary eddies, and the latter term is a representation of the transient eddy contribution. Continuing work concerning the devastating Ice Storm of January 1998 reveals the planetary-scale character of the water vapor □ransports (Figure 6) that extends from the subtropical regions of the North Atlantic Ocean into the Gulf of Mexico and northward into the northeastern United States and southeastern Canada. Cases such as this illustrate the river effect discussed earlier in this chapter in reference to Newell and Zhu's work.
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