Significant Gales on the 8th


2016-01-08-1738_250km_sri
Bermuda Weather Service radar imagery for Bermuda showing spiral bands of showers around the deep low as it made its closest point of approach on the afternoon of the 8th. 

A deep low passed to the near north of Bermuda on Friday brining gale force southwesterly winds to the island for several hours before veering to the west and northwest and diminishing into the evening. This followed a day of steady, moderate rains that accumulated around an inch islandwide. The low responsible had a minimum central pressures below 990 mb and maximum sustained winds around 55 kts.

Peak gusts officially reached 51 kts (59 mph) at the airport. Other unofficial gusts were measured at 75 kts (86 mph) at Commissioner’s Point WindGuru Spot, 59 kts (68 mph) at MARops via Skylink-Pro, and 37 kts (43 mph) at my PWS. These winds resulted in some isolated power outages and transportation disruption.

Following the Shapiro-Keyser Cyclone evolution model, the low fits the mature “warm seclusion” stage. This is fairly common in ocean cyclones but is more typical further north in the Atlantic.

2016-01-08-1745UTC-ir4-l
Infrared Satellite imagery showing the clouds associated with the low near Bermuda and accompanying fronts to the north and east.

However, because the low formed so far south and was headed east it is remaining over fairly warm sea surface temperatures. Its thermal structure, plus a detachment from fronts and continued convection around the center of the low could allow a transition to it being sustained by more tropical processes. This would allow the low to become a subtropical or tropical cyclone. Fortunately, it is tracking into the depths of the Central Atlantic and isn’t expected to pose further threat to land for at least five days. The National Hurricane Center is monitoring this low for a 40% chance that it transitions to a subtropical or tropical cyclone in the next 48 hours as it continues to produce storm force winds over the open Atlantic.

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