A synoptic climatological approach to the identification of January temperature anomalies in the United States

For several decades a singularity phenomenon known as the “January thaw” (most likely originating out of New England folklore) has engaged the scientific community. To date a causal mechanism for the thaw has not been determined, which consequently, has led to the widespread dispute and uncertainty of the January thaw’s existence. The lasting intrigue surrounding the thaw is attributed to the apparent recurrent, anomalous warm spells associated with an event that invades during the coldest time of year.

Considering the uncertainty surrounding the physical mechanisms, and even the existence of the thaw, this research utilizes a synoptic climatological approach to identify the January thaw signal across the US from 1948-2001. Specifically, this research addresses the inter- and intra-regional variability of the January thaw’s presence through an assessment of air mass frequency. This methodology contributes to understanding whether abrupt changes in air mass types over a several day period are contributing to systematic thaw conditions. In addition, as initial observations indicate that a possible “January freeze” occurs across the western US, this anomalously cold singularity is also examined.