Ocean Effect Snow
**The above radar shows the strong ocean effect snow band over Essex County, MA in the afternoon on January 2nd**
The January 2nd coastal storm was certainly an interesting event, especially for folks in Massachusetts. While most in eastern parts of the state generally received 8 - 13 inches of snow, localized spots of Essex County were buried under 20 - 25 inches! So what caused this isolated swath of nearly 2 feet? Ocean effect/enhanced snow is the answer. With winds set up out of the northeast, single digit air was flowing over ocean temperatures in the low 40's, creating an unstable atmosphere. In fact, the temperature difference between the air mass and the water was nearly 30 degrees! This combined with the coastal storm pumping in plenty of moisture off the ocean enabled isolated but very intense snow bands to develop in Essex County which lasted for multiple hours. Actually, a very similar scenario occurs during lake effect snow as strong instability develops when cold Canadian air passes over the relatively warm lakes. Ocean effect snow is not terribly common for coastal Massachusetts but when it does occur, extremely heavy snow can bury parts of the coastline.