A stalled cold front was drawn northwards into the approaching front that was moving off of the United States East coast. This stalled front transformed into a trough that paralleled the approaching cold front from the United States. It then was pulled northwards over Bermuda and enhanced by jet stream winds.
Behind the front, a trough of low pressure began to develop along the United States East coast and move out to sea with the front. It was enhanced by an upper atmospheric pocket of colder air. The storm center stayed relatively far south and drove the front forcibly through the Bermuda area including several thunderstorms that exhibited severe characteristics warranting a Severe Weather Watch from the Bermuda Weather Service.
The trough of low pressure stayed far enough south that the southern end of the trough axis was able to pass just to the north of Bermuda. The trough had rapidly deepened in the time it took to get here and the associated low pressure was only just beginning to pull northwards. Bermuda was therefore on the southern periphery of the core of strongest winds and the Bermuda Weather Service managed to record sustained winds of 46mph with gusts to 64mph during the height of the storm between 9 and 10pm January 3rd.
The winds came from an unusual direction to usher in such cold air – the west-southwest. In fact, the trough that created the strong winds in the first place was also affecting the wind direction; after all a trough is only a notable shift in wind direction along a line or axis resulting in convergence, lift, and therefore convection and precipitation. The gales subsided throughout the day on the 4th, but cold air was indeed ushered in by them. Despite ocean temperatures remaining in the mid 60s, air temperatures struggled to reach 61F as reported by the Bermuda Weather Service for January 4th. No record low temperatures were reported by the Bermuda Weather Service.
In fact, it was this same storm that brought the coldest air of the season to the United States East as well. It brought blizzard conditions and lake effect snows to the Great Lakes region (including Canadian sections), and record hard freezes all the way to Northern Florida where temperatures reached the upper 10s and low 20s ending the growing season. However, unlike the last few years, this cold air doesn’t appear to be here to stay and should modify or be replaced for next week.