The SSTA pattern is very warm. Easterly component of wind will increase the amount of moisture flowing into the developing storm. Heavy rain causing a flood risk is likely in east/northeast Virginia to southeast Maryland while well inland where temperatures stay cold over-achieving snowfalls will occur.

The Nino34 SSTA cool peak for La Nina was late last October. Since that time La Nina is less intense and choppy. Subsurface water in the equatorial East Pacific is not quite as cool as October.

A vigorous negative phase of the arctic oscillation (-AO) is ahead. In the Dec. 11-25 period, forecast models agree on a -2.2 signature of the AO. The GFS identifies the attendant high-pressure block near the polar region. Interestingly, the polar vortex split which results in 4 northern mid-latitude upper troughs are all located farther north than usual for a full-throttle -AO episode.

In North America nearly the entire continent trended drier during SEP/OCT/NOV most notably across the Southwest U.S., Great Basin and California. Additional drying took place in Alaska and much of Canada. The catalyst to the drier climate is the warm SSTA pattern either side of North America promoting anomalous dry/warm high pressure. The Southeast U.S. wet pattern was fueled by tropical cyclone activity. Central America also reversed much wetter due to late season tropical cyclones.