Review of the past hurricane season reports of hurricanes, tropical storms, tropical disturbances and related flooding during



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WORLD METEOROLOGICAL ORGANIZATION

___________________________________________

RA IV HURRICANE COMMITTEE


THIRTY-THIRD SESSION
GRAND CAYMAN, CAYMAN ISLANDS
8 TO 12 MARCH 2011




RA IV/HC-XXXIII/Doc. 4.2(2)

(31.I.2011)

________

ITEM 4.2


Original: ENGLISH


REVIEW OF THE PAST HURRICANE SEASON

REPORTS OF HURRICANES, TROPICAL STORMS, TROPICAL

DISTURBANCES AND RELATED FLOODING DURING 2010

(Submitted by Canada )
1. Introduction
1.1 Three tropical cyclones entered the Canadian Hurricane Centre (CHC) Response Zone (RZ) in 2010. The CHC issued bulletins on 4 storms – one (Tropical Storm Colin) which dissipated before entering the RZ. The second storm requiring activation of the CHC forecast desk was Hurricane Danielle which affected the southernmost portion of the Grand Banks off Newfoundland on August 30th. Long-lived Hurricane Earl tracked over Nova Scotia on September 4th. Hurricane watches and tropical storm warnings were posted for a large portion of the Maritime Provinces. About two weeks later Hurricane Igor struck Newfoundland on September 21st with severe impacts. Hurricane watches and tropical storm warnings were issued for the island portion of the province. The CHC issued a total of 79 information statements during the 2010 Hurricane season.
1.2 Although the CHC did not issue any official bulletins after Hurricane Igor, Tropical Storms Nicole and Tomas contributed moisture to long, stationary frontal systems over the eastern U.S. and Canada in late September and early November. Remnants of Nicole brought major flooding and caused two fatalities in the southern portion of the province of Quebec while Tomas’ remnants over parts of New Brunswick and Nova Scotia provinces spawned serious flooding that washed away roads and bridges. The Hurricane Season was essentially the most damaging and costly for Canada in over 50 years.


BULLETIN SUMMARIES

2010

2009

2008

2007

2006

2005

2004

2003

2002

Hurricane Information Statements (WOCN3X/7X CWHX)

79

37

90

48

93

87

104

113

68

Number of Storms Represented by these Bulletins

4

2

6

4

5

7

8

8

8



2. Colin
2.1 Storm
Colin was a weakening tropical storm as it approached Bermuda from the south on August 8th. The storm dissipated to a tropical depression near Bermuda and did not enter the CHC RZ. Eleven bulletins and track forecasts were issued by the CHC in anticipation of Colin crossing the offshore marine forecast district.

3. Danielle
3.1 Storm
Originally expected to travel south of the Response Zone, the center of Hurricane Danielle tracked just south of the Southern Grand Banks marine forecast district off Newfoundland on August 30th. It was a category-1 storm at the time but had once been at category-4 intensity. An upper-level trough of low pressure was responsible for maintaining Danielle on a more northerly heading on the 29th. The trough was also responsible for an earlier beginning to extratropical transition than was expected on Friday the 27th. Although the maximum winds associated with Danielle were decreasing as it passed the Grand Banks, its central pressure underwent a final period of deepening as it moved away from the Banks.
3.2 Conditions
The only conditions related to the storm over Canadian territory were in the form of gale-force winds at buoy 44140 at 42.9N, 51.5W. Significant wave heights near 7 m were measured by the buoy. Much of this was from previously-generated swell from Danielle as it travelled northeastward. Ocean swell also reached southern Newfoundland but no adverse effects were reported. There was a trough extending north of the hurricane as it passed by the buoy, with winds originally veering as the hurricane drew near, then backing quickly as it passed by to the south.

3.3 Impacts
There were no obvious impacts over land.
3.4 Warnings & Information Statements
Gale warnings were issued for the southern halves of the Southeast and Southwest Grand Banks marine forecast district at 2230Z August 29th (8:00 p.m. local time). Given that buoy 44140 straddles the boundary between these forecast regions, and that its winds were near gale-force, we can consider the gale warnings as being successful forecasts. Wave height forecasts were very good, mentioning 5 to 7 m Monday morning, August 30th. Significant wave heights near 7 m were reported from 09 to 12Z on August 30th at buoy 44140. A total of 12 information statements were issued on Danielle, including a pre-emptive one on Friday, August 27th at a point where it was appearing that Danielle would not require activation of the desk.
3.5 Coordination and Communications Effort

The CHC originally contacted the Newfoundland and Labrador Weather Office – NLWO in Gander on Friday the 27th to discuss a pre-emptive bulletin regarding Danielle and that the track of the storm would be monitored that weekend. Late on Saturday the 28th, with the trough affecting Danielle’s course, the desk was activated, and on Sunday the 29th there were some communication calls between the CHC and the NLWO, as well as one with the Canadian Meteorological Centre to discuss the numerical models. The CHC and the National Hurricane Center (NHC) in Miami had a final coordination call Monday morning, August 30th. There were a few calls coming in to the CHC from media over the course of Danielle’s life, primarily inquiring about possible impact of the storm in eastern Canada and explanation of why the season had been so quiet up until that point.



4. Earl
4.1 Storm
Earl formed in a traditional manner off the Cape Verde Islands on August 27th and moved westward for several days, attaining hurricane strength not Far East of the Leeward Islands of the Caribbean. Earl moved west-northwest brushing the northeastern Caribbean Islands while attaining category-4 intensity. From September 1st to 3rd, the hurricane brushed past Cape Hatteras, NC then Cape Cod, MA while rounding the western flank of the Subtropical High. As Earl moved northeast late on the 3rd its intensity dropped to category-1 status, while the wind field expanded significantly. The central pressure of Earl remained in the low 960-millibar range as it made landfall as a 120-km/h category-1 hurricane about 35 km southwest of Liverpool, Nova Scotia at 10:30 am ADT, September 4th. Earl was a 100-km/h tropical storm as it moved across eastern Prince Edward Island between 3 and 4 pm. The forward speed of motion was 75 km/h while crossing central Nova Scotia and into the Gulf of St. Lawrence. There was a significant slow-down in forward speed and rapid weakening in intensity as Post-Tropical Storm Earl approached southeastern Labrador.
4.2 Conditions
Earl brought high winds to much of southern and eastern Nova Scotia with gusts over the threshold for a hurricane (>120 km/h) and sustained overland wind speeds of mid tropical-storm force. Several stations in and around Halifax (urban area) registered peak winds near 110 km/h. Rainfall was not significantly heavy with this storm, although when it was accompanied by the high wind gusts, conditions were certainly indicative of a hurricane. The faster forward motion (faster than initially expected) helped reduce the rainfall amounts for many areas. The most rain fell left of the storm track over central and northwestern New Brunswick where up to 75 mm (3 inches) was measured, enhanced slightly by the presence of a weak front that was approaching that province. Ocean conditions were turbulent and consistent with a category-one hurricane or strong tropical storm. Significant wave heights of 10 to 13 m (33 to 43 feet) were recorded with peak waves up to 23 m (75 feet) at the Halifax Harbour buoy. Storm surge in Bedford Basin (head of Halifax Harbour) reached 120 cm or 4 feet. A listing of some of the highest rainfall and strongest wind data is shown below:


Station

WindGusts (km/h)




Station

Rainfall (mm)

Beaver Island, NS

135 (104 sust.)




Edmundston, NB

76

McNabs Island, NS

130 (104 sust.)




Florenceville, NB*

67

Wreckhouse, NF

129




St. Stephen, NB

55

Osborne Head, NS*

128




Halifax Airport, NS

52

Drum Head, NS*

127+




Kejimkujik Park, NS

46

Halifax Airport, NS

120




Charlottetown, PEI

30

Shearwatter Jetty, NS

117










Stephenville, NF

115










Antigonish, NS*

110










* Private or volunteer observation


Buoy

Max wind **

Sust./gust (kts)

Significant

Wave Height (m)

Maximum Wave Height (m)

Halifax Harbour 44258

46/67

10.1

23.3

LaHave Bank 44150

45/66

13.1

25.1

NE Channel 44024

45/60

9.0

N/A

East Scotian Slope

37/48

10.3

18.3

** Sustained wind is a 10-minute mean at the 5-m level above water surface


4.3 Impacts

The primary impact from Earl was wind damage to trees, and related problems. Numerous trees were uprooted or snapped-off over central and eastern Nova Scotia as well as parts of western Newfoundland. There were many large limbs falling onto the streets in the Halifax area which resulted in power failures on a large scale. There were up to 200 000 Nova Scotia power customers that were without power at some point during the storm. It was a few days before power was restored for the hardest-hit areas such as eastern Halifax County and Guysborough County in Nova Scotia. Corner Brook in Newfoundland suffered major tree damage as the Tropical Storm Earl passed to the west over the Gulf of St. Lawrence. Trees and large branches were also reported downed in New Glasgow and Antigonish, Nova Scotia. Winds also caused minor damage to roofing and cladding materials. Light to moderate damage to signage was also observed.
There was no significant surge or wave-related damage owing to the low tide at the time of the hurricane’s arrival. The high winds did blow sea spray inland which caused deciduous/hardwood foliage and vegetation to suffer salt burn which consequently shriveled and turned brown. High winds also shredded and thinned-out foliage well inland on trees that were highly exposed to the winds. Little in the way of rainfall impacts were reported in Nova Scotia, Prince Edward Island and Newfoundland. There was some minor street flooding in PEI and New Brunswick.
4.4 Warnings & Information Statements
The CHC first issued a preliminary statement on Earl Monday morning (August 30th – 5 full days prior to the event). Media interest was very intense for this event and it began on Monday. The first regular bulletin was issued at 3 pm Atlantic Daylight Time (ADT) Tuesday, August 31st, 2010. Bulletins were issued every 6 hours thereafter, with 3-hourly intermediate bulletins from midnight Thursday night, onward.
Tropical storm watches were first posted for southwestern Nova Scotia early on Thursday the 2nd. The first hurricane watches were issued for southwestern Nova Scotia around 3 pm Thursday. Tropical Storm warnings were issued early Friday morning for much of Nova Scotia and Prince Edward Island, followed by parts of southern New Brunswick that afternoon. A Hurricane Watch was extended eastward at 9 am Friday to include Lunenburg and Halifax Counties. Tropical Storm warnings were issued Saturday afternoon at 4 pm NDT for western Newfoundland once it became apparent that Earl was retaining tropical characteristics farther north than earlier thought. This was a result of the storm’s rapid forward motion on Saturday.
Lead times for the tropical storm warnings for the Maritime Provinces averaged about 24 hours ahead of the storm’s arrival. The tropical storm warnings for western Newfoundland were in the 8- to 12-hour range.
Out of the eight official public forecast regions under the hurricane watch, 4 of them experienced hurricane-force gusts and 1-minute-adjusted sustained wind speeds were not far below hurricane-force (Halifax and Guysborough Counties for instance). There were 34 information statements issued by the CHC. The regional weather offices (the Atlantic Storm Prediction Centre (ASPC) and the NLWO) also issued 34 Marine wind warnings during the event.
4.5 Coordination and Communications Effort
With Earl having been a long-lived storm, media interest began very early – a full 5 days prior to its impact. The NHC track maps which extend out to 5 days marked the beginning of this heightened level of interest starting on Monday, August 30th. Over the days that followed there were numerous coordination efforts conducted with the Atlantic Storm Prediction Centre, Newfoundland and Labrador Weather Office, the Canadian Meteorological Aviation Centre – East (CMAC-E), the media, and other government departments including the emergency management offices.
Three technical media briefings were arranged during the week (Wednesday (September 1st), Thursday (2nd) and Friday (3rd)) from 1 to 2 pm. A fourth teleconference-style briefing was held on Saturday (4th) morning (day of the event) to communicate latest storm conditions and impacts. About 100 questions were answered during the technical briefings with about 220 individual media requests filled throughout the event and leading up to it. A Warning Preparedness Meteorologist (WPM) from the CHC was situated at the Emergency Operations Centre during the hurricane to aid in coordination and messaging. Teleconference calls were held with other forecast offices (such as the CMAC - E office in Montreal) and for the WPMs after each CHC forecast issuance. Coordination between the CHC and the NHC occurred as watches and warnings were put in place on Thursday. Key coordination calls occurred late Friday and throughout Saturday, Sept 4th as the storm accelerated.

There was a period of approximately 10 hours prior to the landfall where the NHC was posting Earl as a tropical storm, while the CHC was messaging on it as a hurricane (5 knots difference). This generated some confusion, and the discrepancy was not intended. Discussions after the season concluded with Earl being classified as a hurricane landfall, but a strong tropical storm in the hours leading up to landfall. Since the overall motion of the storm was accelerating, this small increase in wind at landfall is reconcilable, although 5 knots of maximum sustained wind speed estimate is certainly within observational uncertainty.


5. Igor
5.1 Storm
Igor formed near the Cape Verde Islands off Africa on the 8th of September, 2010 and moved on a general westward course across the tropical Atlantic in typical fashion. It did not attain hurricane strength until early on September 12th. The most intense state of the storm occurred early on the 15th when its minimum central pressure fell to 925 mb and maximum winds reached 250 km/h – just below category-5 intensity. Thereafter while on a northwestward heading, the hurricane weakened to category-1 but greatly expanded and maintained a very low central pressure in the 940-mb range. Igor tracked just west of Bermuda early on the 20th delivering category-1 wind conditions. Beyond Bermuda Igor tracked northward then north-northeastward and began to accelerate. A sharp frontal system over Newfoundland became stationary on September 20th and acted as a conduit for moisture and extremely heavy rainfall streaming northward from the hurricane. Igor responded to an upper-level trough of low pressure associated with the front early on the 21st, consequently undergoing re-intensification throughout the day while tracking toward (then passing just east of) Newfoundland’s Avalon Peninsula. The central pressure fell to near 950 mb and winds increased by about 20 km/h to near 140 km/h as it slammed eastern Newfoundland. The trough interaction imparted a more northerly trajectory to the storm which eventually merged with another large area of low pressure on September 23rd.
A detailed operational storm summary (AWCN16 CWHX) was prepared within 2 days following the event serving as a meteorological assessment and historical perspective for the media and ensuring consistent data communication internally and with partnering agencies. This summary in its original form appears online HERE.
5.2 Conditions
Hurricane Igor and the associated front and trough were the story behind the intensity of this combined, extratropical transition event. Rainfall was the greatest issue with Igor with well over 200 mm (8 inches) falling over the Burin and Bonavista Peninsulas. A large area of 100+ mm rainfalls (4+ inches) occurred over the eastern half of the island. Winds were also particularly strong in the north to northwesterly “baroclinic jet” that accompanied the passage of the knife-edge front and Igor’s center during the morning and afternoon of September 21st. Sustained hurricane-force winds (~120 to 130 km/h) were recorded with gusts in the 150- to 165-km/h range. Over the marine forecast district, 13-m (~43-ft) maximum wave heights were reported east of the storm track, with 12-m (~39-ft) maximum significant wave heights reported at the Hibernia oil platform, about 250 km east of the track. Peak wave heights of 25 m (~80 feet) occurred to the east of the track. Also at Hibernia, maximum sustained winds of 174 km/h were reported by the 140-m level (459-ft) anemometer. Storm surge of 70 to 100 cm (~2 to 3 feet) was measured by tide gauges around the eastern portion of Newfoundland.

Station

WindGusts (km/h)




Station

Rainfall (mm)

Cape Pine*

172 (122+ **)




St. Lawrence

238

Sagona Island

163 (113 **)




Bonavista

235 ***

Bonavista

155 (122 **)




Lethbridge *

194

Pouch Cove*

147




St. Pierre/Miquelon (FR)

160

Pool’s Island

146 (104 **)




Pouch Cove *

142

St. John’s (CYYT)

137 (92 **)




St. John’s (West)

134

Grates Cove

135




Gander

124

St. Pierre (France, Isl.)

135 (91)










Argentia

132










* Private or volunteer observation

** 10-minute sustained



*** Rain gauge failed/overflowed around the 200-mm mark, radar-based rationale thereafter


Buoy

Max wind **

Sust./gust (kts)

Significant

Wave Height (m)

Maximum Wave Height (m)

Banqureau Bank 44139

59/75

8.9

16.9*

Nickerson Bank 44251

54/73

8.1

16.2

Tail-of-the-Bank 44140

53/70

12.5

21.0

SW Grand Bank 44138

53/68

12.5

25.5

NE Burgeo Bank 44255

38/49

4.2

6.5

* Data record from this buoy actually indicated a maximum of 28 m (92 feet) which will require further analysis to verify.
5.3 Impacts
There was extensive damage to roads, bridges and some buildings over a large portion of eastern Newfoundland from excessive rainfall runoff and swollen rivers. The impacts were most serious on the Bonavista and Burin Peninsulas where over 150 communities were cut off from the principle road network due to road washouts. These washouts were severe, requiring complete bridge replacements and rebuilding of roadbeds. One person was killed when the road he was driving on washed away beneath him. Torrents of water from overflowing rivers destroyed some buildings and changed the course of some rivers. Large portions of river banks and roads were removed by the extreme river flows which set new records. In some cases, full-grown trees were felled by the surging water flow. The Canadian military was brought to Newfoundland along with federal financial aide to help with the recovery efforts. Temporary bridges had to be erected to reconnect communities with essential services such as fuel and food. This took a couple of weeks in some cases. A portion of the Trans-Canada Highway in Terra Nova National Park was washed away creating a giant ravine about 30 metres (~100 feet) across. This was the most important road connection to be restored since it resulted in complete disconnection of Newfoundland’s main population from land.
In addition to the flooding, very high wind speeds were witnessed over the eastern peninsulas of Newfoundland toppling many trees (especially in urban areas), and causing minor to major structural damage which included complete roof loss and curtain wall collapse.
Damage was estimated by to be in excess of $200 million.
Two important quotes from Dennis Shea, Manager, Plans and Operations, Fire and Emergency Services, Newfoundland and Labrador:
Igor has been described as the worst storm in memory. It was unparalleled in that there are no records of hurricanes/post tropical events of this magnitude striking the Province in the modern era.”
Hurricane Igor changed the mindset of the people of the Province; no longer can we look at hurricanes as something that happens elsewhere. The storm will serve as the benchmark against which all future storms will be measured.”
5.4 Warnings & Information Statements
The CHC first issued a preliminary statement on Igor Friday afternoon, September 17th which was 4 days prior to the main event (Tuesday the 21st). The intention of this early bulletin was to officially begin Hurricane Centre monitoring of the storm prior to the weekend as a heads-up. Media interest was much less than for Hurricane Earl in the Maritime Provinces two-and-a-half weeks earlier. This lower level of media (and public) interest was likely due in part to the different track scenarios. With Hurricane Earl, the likelihood of impact somewhere in Atlantic Canada was greater further ahead in time than was the case for Igor which was much further out in the Atlantic Ocean.
Regular CHC bulletins began in the afternoon of Saturday, September 18th. Track forecasts were consistent with Igor passing through the central portion of the Grand Banks from Saturday thru till Monday evening, September 20th. During the early part of Tuesday the 21st, it was becoming more apparent that Igor was going to track farther to the northwest and closer to Newfoundland. However, even during the day of the event, the position and track forecast had to be continually adjusted closer to land as the details of the upper-level trough influence was evolving. Intensity forecasts were highly consistent during the days leading up to the event for Igor’s passage past Newfoundland, indicating a transitioning hurricane with 120- to 140-km/h winds. Early on Monday the 20th, forecasts began to reflect a possible re-intensification trend during the extratropical transition process over the Grand Banks.
Although the rainfall threat of this event was anticipated 2 to 3 days in advance, the wind threat was not specifically expected to be an issue over land until the day before Igor’s arrival (Monday the 20th). Computer models on Monday began to indicate an increased likelihood of a very strong wind jet on the cold side of the interacting front north of Igor. Correspondingly, tropical storm warnings and wind warnings were posted Monday afternoon for eastern Newfoundland, which falls within the target lead time of about 24 hours. Hurricane watches were issued early on Tuesday the 21st as it became even more apparent that the vigorous trough-hurricane interaction was going to bring high winds across the eastern peninsulas.
There were 22 information statements issued by the CHC on Hurricane Igor.
5.5 Coordination and Communications Effort
There was much less media interest leading up to the Igor event than for Hurricane Earl. Media is often more interested in the major wind events versus rainfall events, which was also part of the lesser level of interest with this storm. The CHC and the NLWO began to raise the alert for very high winds on Monday, September 20th. Media interest ramped-up during the event, and in the days after the extreme impacts became known. There were about 35 specific media requests for the CHC, some of which were directly to the NLWO were later handled by the CHC. One teleconference-based technical media briefing was arranged by the CHC and Environment Canada’s Communications Department Tuesday morning (the 21st – day of event) for media and representatives in Emergency Management.
Interoffice communication between the NLWO and the CHC began early on Friday the 17th. This was prior to the CHC desk being staffed, and was important for establishing early communication to decide what would be the best way to describe the event in the long-range weather forecasts. Over the weekend (September 18th and 19th) there was little media interest. Communication between the CHC and the NLWO continued throughout the weekend. At 11 am ADT on Monday, September 20th, a conference call briefing by the CHC for the Canadian Government Operations Centre (GOC) took place. Another was held Tuesday morning at 11 am ADT.
The WPMs worked closely with Fire and Emergency Services of Newfoundland and Labrador who were primarily responsible for alerting municipalities and other sectors of possible threats. The CHC and the NHC in Florida communicated on the issuance of watches and warnings and the designation of Igor’s post-tropical status on September 21st.
__________


Directory: pages -> prog -> www -> tcp -> documents
documents -> Review of the ra IV hurricane operational plan
documents -> Cyclone programme
documents -> World meteorological organization technical document
documents -> World meteorological organization ra IV hurricane committee thirty-fourth session
documents -> World meteorological organization ra IV hurricane committee thirty-third session
documents -> Review of the past hurricane season
documents -> Ra IV hurricane committee thirty-fourth session ponte vedra beach, fl, usa
documents -> World meteorological organization ra IV hurricane committee thirty-second session
documents -> World meteorological organization ra IV hurricane committee thirty-fifth session
documents -> English only review of the tropical cyclone operational plan for the south pacific and south-east indian ocean

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