Post-tropical Hurricane Sandy in Ontario

Hurricane Sandy was an exceptionally large storm which displaced thousands of birds to the lower Great Lakes, some of which were unprecedented in their rarity or number. This note covers the events leading up to Sandy, and its aftermath as it passed through Ontario from both meteorological and ornithological viewpoints.
(B. Holden) 

What would eventually become Sandy was labeled as a tropical depression by the National Hurricane Center (NHC) at 1200 UTC on 22 October 2012, roughly 300 nautical miles south-southwest of Kingston, Jamaica. The system organized quickly and was deemed a tropical storm six hours later, receiving the name Sandy. Further development was gradual but progressed steadily. Sandy became a hurricane at 1200 UTC on 24 October and made initial landfall seven hours later in Jamaica as a 75kt category one hurricane. As Sandy emerged over open water north of Jamaica, the storm intensified rapidly, reaching category three just prior to its second landfall in Cuba. After weakening across Cuba due to interaction with land Sandy continued northwards into the Bahamas. It was during this period, from 25 – 27 October, that a complex series of meteorological events began, setting the stage for the final track of Sandy. 

The interaction with a trough of cold air arriving from mainland North America provided energy in the form of baroclinic forcing and began processes associated with an extratropical transition, allowing Sandy’s wind field to expand dramatically. Extratropical transition was ultimately incomplete, and Sandy was able to maintain full tropical storm status as a warm-core system. The complex series of events caused frontal structures to form within the cyclone away from its warm core, which is highly unusual and gave Sandy the appearance of a hybrid tropical/extratropical system. 

Sandy continued to grow in size as the cyclone moved northwards from Bermuda to offshore North Carolina. On 29 October, Sandy reached an anomalous blocking pattern (high pressure) in the North Atlantic, perhaps the defining moment from an Ontario birding standpoint, causing a highly unusual change in track to the north and then northwest as Sandy began final course towards the coast of New Jersey. This blocking allowed a second trough over the southeast US to provide a notable boost to the baroclinic forcing of energy into the hurricane while the change in direction moved Sandy again over warm Gulf Stream waters allowing to intensify to secondary peak of an 85kt category two hurricane on 1200 UTC 29 October 2012. 

Over the next several hours, Sandy began to transition to an extratropical cyclone once again. This time the process was accelerated by the additional injection of cold air and cooler water near the coast of New Jersey (i.e., to the west of the Gulf Stream). When only 45 nautical miles northeast of Atlantic City, New Jersey, the NHC declared Sandy a fully extratropical system at 2100 UTC on 29 October. Post-tropical Sandy made final landfall at 2330 UTC in New Jersey with an estimated intensity of 75kt winds. Sandy weakened steadily and moved slowly west-northwest to north before losing a defined centre over northeast Ohio around 1200 UTC on 31 October. Following this event, the remnants of Sandy moved northwest to northeast over Ontario in the days before eventually merging with a low-pressure system over eastern Canada. 

Prior to the arrival of the storm, I postulated the potential impacts Sandy could have on avian migration and vagrants into southern Ontario. The basic premise was that migrants and vagrants would occur from the direction of origin of the wind field impacting an area. As the storm progressed, the impacts would compound as new and stronger winds directed birds to southern Ontario from different locations. They were informally dubbed Phases 1, 2, 3 and 4. A brief overview is presented below: 

Phase 1: Initially strong north winds associated with a trough of cold air would draw migrants and potential vagrants southwards (i.e. from James Bay) into the southern Great Lakes region.

Phase 2: As the centre of the storm approached, the counter clockwise motion of the cyclonic storm would then bring northeast winds into southern Ontario and potentially birds from the St. Lawrence Seaway and nearby areas. 

Phase 3: An unusual frontal boundary-like feature was present within Sandy. As the remnants of Sandy pushed closer to Ontario, somewhat resembling a “back door warm front”, winds came directly from the east coast of the US into southern Ontario (specifically Lake Ontario). 

Phase 4: If any birds were trapped within the eye (or remnant core), the passage of this portion of the storm (and any accompanying southerly winds) could displace them. 

Beyond the predicted Phases it was also noted that storm conditions can lead to observers detecting noteworthy birds that were already present prior to the storms arrival. 

My personal bird watching notes include:

28 October: Several hours lake watching at Van Wagner’s Beach, with notable sightings being single flocks of Brant and Sanderling, which correlated to the predicted effects of Phase 1. 

29 October: I remarked at the general lack of interesting observations during the morning hours at Van Wagner’s Beach before 10 Black-legged Kittiwakes were recorded from mid-afternoon to dusk. This is contrasted by observers at the Point Edward Lighthouse in Sarnia who had a notable day with sightings of Brant, Black-legged Kittiwake, Red Phalarope, Parasitic Jaeger and Franklin’s Gull. These observations indicate that the effects of Phase 1 were being felt at all around southern Ontario; and that the effects of Phase 2 were likely just starting on Lake Ontario by mid- to late-afternoon. 

30 October: powerful north-northwest to north-northeast winds continued in the morning; however, they eventually shift northeast by mid-morning. The remnant core of Sandy was much closer to Ontario than the previous day and many observers around southern Ontario reported remarkable numbers and exciting vagrants, including record high counts of Black-legged Kittiwake. This was likely attributed to the continuing and compounding effects of Phases 1 and 2 in southern Ontario. Perhaps the most notable observations of Sandy occurred on this day, as multiple Leach’s Storm-Petrels were reported on Lake Ontario as well as a single Wilson’s Storm-Petrel. The observations of storm-petrels strongly correlated with the passage of an abnormal frontal-boundary feature within Sandy — bearing some resemblance of a “back door warm front”. The passage of this feature came with a change in wind direction from north-northeast to east-northeast at Van Wagner’s Beach. This is strongly linked to the beginning of Phase 3 and also likely indicates why these species were not recorded by other observers on Lakes Erie or Huron this day (which stayed within the effects of Phases 1 and 2). 

31 October: the enlarged and weakening core of the system moved over a large area of southern Ontario. Many observers took to the field in hopes of relocating the remarkable birds recorded on 30 October, yet few were successful, likely due to calm conditions. If any birds were to occur in Ontario under the effects of Phase 4, the passage of this feature over lakes Erie and Ontario would have made it the ideal location to drop any noteworthy individuals. 

1 November: the core of the system was pulling away from Ontario, and powerful west-northwest winds pushed through southern Ontario. This dramatic change in direction meant that locations previously watched vigorously (e.g., Van Wagner's Beach and the Point Edward Lighthouse) were either unmanned or did not produce sightings of note. I moved to Waverly Beach in Fort Erie believing it would be the best location to record birds associated with Phase 4. While no species were recorded that would be associated with displacement in this manner, several remarkable birds were recorded, the most notable being an adult Ross’s Gull (Phase 1 origin?). The lingering effects of Phases 1 through 3 were evident with continued sightings of Brant, Black-legged Kittiwake and Pomarine Jaeger.