Figure 7. Low level (925-mb) vector wind anomalies and total precipitable water anomalies (shading, units are mm) for specified periods. The top and bottom panels correspond to heavy precipitation events in the northwestern United States, while the middle panel corresponds to a cool, relatively dry period in the Northwest. The wet periods are characterized by abnormally large amounts of moisture extending from the subtropics into the northwestern United States. Note the extremely strong fetch of moisture extending from the subtropical North Pacific during 24-30 December. This subtropical moisture fetch is notably absent during the cool dry period.