RA IV/HC-35/Doc. 4.2(2), p. 1
WORLD METEOROLOGICAL ORGANIZATION______
RA IV HURRICANE COMMITTEE
THIRTY-FIFTH SESSION
WILLEMSTAD, CURAçAO
8 TO 12 APRIL 2013 / RA IV/HC-35/Doc. 4.2(2)
(28.II.2013)
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ITEM 4.2
Original: ENGLISH
REVIEW OF THE PAST HURRICANE SEASON
Reports of hurricanes, tropical storms, tropical disturbances and
related flooding during 2012
Report from Canada
(Submitted by Canada)
Five tropical cyclones entered the Canadian Hurricane Centre (CHC) Response Zone (RZ) in 2012 with two of those on the very edge of the zone. The CHC issued bulletins on four storms in total. Two storms affected land while two others were purely offshore events. Former Hurricane Leslie struck Newfoundland as a post-tropical storm on September 11th causing minor to moderate wind damage over the eastern peninsulas of the island. On October 29th and 30th the far-reaching influence of Post-Tropical Storm Sandy was felt over southern Ontario and other parts of Eastern Canada. Minor to moderate wind and wave impacts occurred over regions of Ontario near the Great Lakes.
The offshore events included cyclonically-looping Post-Tropical Storm Chris skirting the Southeastern Grand Banks on June 22nd, and Post-Tropical Storm Rafael racing across the southern fringe of the Grand Banks on October 18th. Tropical Storm Michael transitioned to post-tropical over the extreme southeastern portion of the RZ and did not require the issuance of bulletins owing to its small size and distance from the Canadian marine forecast district.
BULLETIN SUMMARIES / 2012 / 2011 / 2010 / 2009 / 2008 / 2007 / 2006 / 2005 / 2004 / 2003Unique Hurricane Information Statements (WOCN3X/4X CWHX) / 64 / 99 / 79 / 37 / 90 / 48 / 93 / 87 / 104 / 113
Number of Storms Represented by these Bulletins / 4 / 8 / 4 / 2 / 6 / 4 / 5 / 7 / 8 / 8
In addition to the conventional tropical events, there was one additional noteworthy cyclone which tracked over the outer fringe of the Grand Banks on July 25th. The low was not named, but exhibited sub-tropical characteristics on satellite (below) and a compact wind field as seen in scatterometer imagery. As a precaution, gale-force wind warnings were issued for a small portion of the marine forecast district in coordination with the CHC.
Unnamed tropical storm-force disturbance on the edge of the Grand Banks off Newfoundland
Below is a summary of the fourprimary events of tropical origin affecting Canadian territory in 2012.
“Chris”
Storm
Hurricane Chris was an earlybut short-lived storm that was active between June 19th and June 22nd. It formed around 35oN from a non-tropical low which was associated with a frontal system. It tracked toward the east then looped north and northwestward on the 21st and 22ndwhile undergoing Extratropical Transition (ET). A second non-tropical low formed to the south of Post-Tropical Storm Chris on the 22nd – interacting with it in a mannerwhich imparted an eastward motion on the post-tropical low followed by dissipation.
Conditions
Being a purely marine storm, there were no impacts over land. Only moderate north and northeast winds (15 kts) were measured at the Tail-of-the-Bank buoy at 42.9oN 51.5oW.
Impacts
There were no known impacts on land or offshore infrastructure.
Warnings & Information Statements
There were five unique information statements issued by the CHC for this event. Waves of 3 to 4 m were predicted and gale warnings were issued for the extreme southeastern portion of the Grand Banks off Newfoundland.
Coordination and Communications Effort
The CHC and Newfoundland and Labrador Weather Office (NLWO) maintained close communication during the short life of Hurricane Chris.
“Leslie”
Storm
Leslie formed from a disturbance in the deep tropical Atlantic in early September and travelled well northeast of the CaribbeanIslands. The tropical storm/weak hurricane spent a prolonged period of timemoving very slowly northward from September 4th to the 9th. Over a five-day period, Leslie travelled about 500 km with a forward speed of only 4-5 km/h, impeded by a large high pressure system to the north. Leslie finally began to approach Atlantic Canada when a front moved off the Eastern Seaboard of the U.S. on September 9th. The front stalled over Nova Scotia as it approached Leslie. Moisture converging along the front streamed across central Nova Scotia. On September 11th, the tropical storm and front merged and tracked into eastern Newfoundland. The official status of Leslie at landfall was ‘post-tropical’ with maximum sustained winds of 65 kts (120 km/h). The landfall of the very broad centre was over the southern tip of the BurinPeninsula. Minimum central pressure at landfall was 969 mb/hPa.
Conditions
Although not directly related to Leslie, the stalled front over Nova Scotia caused serious flooding with observed rainfall rates of 25 mm/hr. This resulted in flash-type flooding around Truro, Stewiacke and Shubenacadie. The rain fell in an area where flooding was exacerbated by return flow up the tidal rivers connected to the Minas Basin and Bay of Fundy. The greatest total rainfall from the Leslie-stalled front was 165 mm (6.5”) at Shubenacadie, Nova Scotia.
Wind impacts were felt over eastern Newfoundland. Wind gusts over hurricane-force from the south and southeast were measured at several stations. The highest gust of 137 km/h was observed at the very-exposed CapePineprivate station on the southern Avalon Peninsula. A summary of wind and rainfall data appears below.
Station / WindGusts (km/h) / Station / Rainfall (mm)CapePine, NL* / 137 / Cow Head, NL / 108
St. John’s, NL / 132 (94 sust.) / Englee, NL / 80
BellIsland, NL / 132 / Stephenville, NL / 77
Bonavista, NL / 124 / Upper Humber, NL / 72
Long Pond, NL / 124 / Daniel’s Harbour, NL / 64
Argentia, NL / 120 / Corner Brook, NL / 63
Storm surge was not an issue during Leslie’s landfall in Newfoundland. This was due to local low tide and a neap phase in the tidal cycle. The highest measured surge was 1.1 m in the communities of Argentia and St. Lawrence.
Impacts
Noteworthy impacts observed include uprooted trees, snapped power poles, damaged roofing and building cladding, broken signage, toppled fences and overturned trucks. Some flooding occurred over western Newfoundlandresulting in undermined roadways, lowland inundation and some stream overflows. Coastal impacts seemed to be related to over-wash and wave-breaking causing minor damage to breakwaters and small structures.
Warnings & Information Statements
The CHC issued 23 unique information statements for this long-lived event. Several of these statements were issued while Leslie was nearly stalled to the southeast of Bermuda. Tropical Storm and Hurricane Watches were posted for the eastern half of Newfoundland late September 9th. Tropical Storm Watcheswere upgraded to warning level during the morning of September 10th, while Hurricane Watcheswere held until the centre of the storm exited the northern coast of Newfoundland. There were 12 public forecast zones under the warning, with all but one verifying (~90%) successfully. Rainfall warnings verified correctly for 15 out of 19 (~80%) public forecast regions in Newfoundland.
Coordination and Communications Effort
The CHC and the NLWO maintained close communication during the long evolution of Hurricane Leslie. Media interest was elevated over a prolonged period given the slow pace of the storm, and it was a particular challenge to communicate the forecast given the much greater-than-normal uncertainty. The approach and subsequent stalling of a front well to the northwest of the hurricane also presented a communications challenge. Many were confused as to which weather system was affecting their area, despite clear descriptions of the differences in the CHC reports. This is a common challenge, given that the boundary between tropical and non-tropical systems is rarely well-defined.
“Rafael”
Storm
Rafael formed in the eastern Caribbean late on October 12thand moved slowly northward, attaining hurricane status late on the 15th. Extratropical transition commenced almost as soon as Rafael became a hurricane. Transition was complete by late on October 17th as the storm’s cloud shield rapidly fanned-out while tracking about 200 km east of Bermuda. Forward acceleration occurred on October 18th while the hurricane-strength post-tropical storm traversed the southern Grand Banks off Newfoundland.
Conditions
Heavy surf was experienced along the southern coast of the Avalon Peninsula of Newfoundland, generated by waves that travelled northward during a period of time when the storm was moving along a straight north-northeastward trajectory. Waves of 4 to 7 metreswith a 16-second period were measured at the Nickerson Bank Buoy about 35 km offshore south of Trepassey, Newfoundland. An elevated water level was witnessed in St. John’sHarbour, likely from the rapid-tide effect described in special bulletins issued by the CHC and the NLWO (see ‘Warnings and Statements’ section below).
There were few weather impacts over land. The high cloud shield from extratropically-transitioning Rafael overspread Nova Scotia and Newfoundland. The heavy rain associated with a front extending well north of Rafael passed not far offshore late on October 17th. Cape Race measured some moderate rainfall for a brief period, amounting to 6 mm.
Waves were estimated to have been above 10 metres well offshore to the right of Rafael’s track. No detailed information was available for analysis of the waves from this storm during the extratropical transition.
Impacts
Large waves and run-up were the primary impact along some southern coastline communities of Newfoundland. In Trepassey, about 110 km south-southwest of the capital city of St. John’s, heavy surf tore apart a 10-metre section of a breakwater connecting two parts of the community. An additional 500-metre portion of coastal roadway suffered heavy pavement damage. More than $1 million in damageswas estimated to have occurred in the area as a result of the far-reaching wave impacts.
Warnings & Information Statements
The CHC issued 18 unique information statements for Rafael. During its post-tropical phase, Rafael travelled rapidly across the southern Grand Banks with a forward speed near 45 kts (80-85 km/h). Special statements were issued to alert the coastal communities in southeastern Newfoundland of rapid changes in water levels and ocean currents. This unique effect is known to occur when sharp wind and pressure features rapidly cross shallow offshore waters. Fortunately these fluctuations occurred prior to the local high tide, so there were no reports of flooding. Hurricane-force wind warnings were posted for the southernmost portion of the Grand Banks. Because of the lack of satellite and weather buoy data, it is not certain whether these winds occurred within the forecast district.
Coordination and Communications Effort
Close coordination was maintained between the CHC and NLWO during this event. There was very little media interest in this event given the far-offshore track. However, there was some interest in St. John’swith the unusual water level alerts, and a local newspaper reported their occurrence on Thursday, October 18th.
“Sandy”
Storm
Sandy formed in the southern Caribbean Seafrom a very large area of cloudiness on October 22nd. Over the next two days the storm moved northward and became a hurricane as it approached eastern Jamaica. Early on October 25th, Sandy deepened to category-three intensity and made landfall in eastern Cuba. After exiting Cuba,Sandy tracked through the Bahamas in a weakened state, as a trough of low pressure approaching from the west created vertical wind shear and eroded convection near the storm center. This attempt at ET was suspended as vertical shear north of the Bahamas decreased and the convection returned to the center while the storm was over warm Gulf Stream waters. The very large storm system continued to be influenced by upper-level trough features that enhanced outflow over the storm environment on October 28th and 29th, resulting in further deepening. Eventually another trough penetrated the hurricane core of the large system leading to the final ET process with strong wind shear over the center and the development of surface fronts. This process occurred just before landfall near Atlantic City, New Jersey when the central pressure had risen slightly from a low of 940 mb to 945 mb. The post-tropical stormtracked west-northwestward into Pennsylvania on October 30th then dissipated on the 31st.
Conditions
The intense post-tropical storm caused extensive damage over a large portion of the Eastern Seaboard of the United States near and well outside of the landfall point in New Jersey. The circulation extended well into Eastern Canada and the Great Lakes. High winds gusted from the north and northeast over southern Quebec and Ontario. Warm southeast winds blew into Atlantic Canada. High waves and storm surge were experienced overLake Huron where the wind blew down the length of the lake. Seas of 5 to 7 metres were measured at buoy 45149 in the southern end of the lake.
Select wind and rainfall data from Canadaappear in the table below:
Station / WindGusts (km/h) / Station / WindGusts (km/h)Western Island, ON / 106 / Kitchener, ON / 87
Burlington, ON / 95 / Oshawa, ON / 87
Point Petre, ON / 93 / London, ON / 80
Toronto Island, ON / 91 / Toronto (Pearson), ON / 80
Quebec (Orleans), QC / 87 / Brier Island, NS / 78
Montreal (Laval), QC / 87 / Blue Water Bridge, ON* / 121
*Bridge connecting Canada and the U.S. at Sarnia, ON. Note however that the wind instruments are atop the bridge, around 60 m – 6 times higher than the accepted standard 10-metre height for wind measuring instruments.
Rainfall was not a significant issue in Canada. The greatest measured amount was 55 mm in Charlevoix, Quebec, while all other primary reporting stations received less than 50 mm.
Waves approaching the south shore of Nova Scotia were in the range of 5 to 8 metres (e.g. buoy 44150). These waves resulted in elevated water levels up to 60 cm along parts of the Atlantic coast in westernNova Scotia.
Impacts
High wind gusts downed tree limbs and whole trees leading to numerous power outages across southern Ontario. There were a few reports of trees falling on vehicles and homes causing significant damage. Sandy was to blame for two fatalities in Canada – one in Toronto when a large sign was blown down and struck a pedestrian. The second occurred in Sarnia, Ontario,when a hydroelectric worker was electrocuted during the post-storm cleanup. The Sarnia area was hit particularly hard as a result of strong north winds off Lake Huron in addition to storm surge and heavy surf. The city was littered with downed trees and power poles, with some reported structural damage to buildings including part of a roof blown off a hotel. Over $10 million in private property damage was estimated to have occurred. Fierce winds and record-high waves disrupted cargo ship travel through Lake St. Clair and the adjacent waterways connecting Lake Erie and Lake Huron.
Warnings and Information Statements
Wind warnings were posted for many portions of southern Ontario and parts of Quebecnear the St. Lawrence River. These warnings verified correctly in Ontario. Rainfall warnings were withheld except for the Charlevoix region of Quebec. Various marine warnings were issued including storm-force winds over Lake Huron.
The CHC issued 18 unique information statements for Sandy, commencing onthe afternoon of Thursday, October 25th. Another statement was issued on Friday, followed by regular statements issued every sixhoursbeginning on Saturday morning, well ahead of the worst of the weather(which arrived in Ontario during the early hours of Tuesday, October 30th). The final summary bulletin from the CHC was issued at 3 pm ADT on October 30th. There were no official tropical-type watches or warnings since much of Sandy’s transformation to a post-tropical storm began before landfall in the U.S.
Coordination and Communications Effort
Owing to the broad expanse of the storm’s impact, an unprecedented amount of media interest and interoffice communications took place. Thechallenge in Canadawas to effectively communicate the threat and how it differed from what was happening in the U.S. This was not unlike the challenge that existed in 1985 with Hurricane Gloria tracking into Canada from the U.S. – interestingly, the event that served as the catalyst for the creation of the CHC. Hurricane Sandy, its extratropical transition and uncharacteristic northwestward track into New England was very well predicted by the numerical weather models,well in advance. This permitted very early communication (5 to 7 days ahead of the event) to occur between the CHC, all of the Meteorological Service of Canada’s eastern and national centres and emergency management partners. The threat of rainfall was communicated earlier during the evolution of Sandy, but as time elapsed, the threat of rain-related flooding decreased. Details about wind impacts were emphasized nearer the event, and on Monday, October29th, the CHC and Ontario Storm Prediction Centre alerted areas around southern Ontarioof specific wind-related impacts such as falling trees and power outages.
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