The Hurricane Season Flood Alert System (HSFAS) is based on forecasted precipitation amounts and seeks to provide communities with flood warning services as a key climate change adaptation and public safety tool. Alerts are provided to communities that have Flood Risk Mapping Studies (FRMS) or have published intensity-duration-frequency (IDF) curves from which precipitation based flood triggers can be derived. The HSFAS is to help communities in the province prepare for storms and avoid future high-cost expenditures in repairs and damages. The HSFAS is operational during the peak hurricane months of June to December. A list of the communities for which alerts are currently provided is shown below.
The report in the Adobe PDF file below has a table that is divided into two categories. These are:
"The National Hurricane Center’s 2016 Atlantic Hurricane Season Outlook (27 May, 2016) favors a near-normal Hurricane Season with a 70% likelihood of: 10-16 Named Storms (including Alex in January); 4-8 Hurricanes (including Alex in January), and 1-4 Major Hurricanes. Concurrently, the Dept. of Atmospheric Science at the Colorado State University (CSU) is calling for near-normal season (updated 1 July, 2016) with 11 Named Storms, 5 Hurricanes, and 2 Major Hurricanes. Major Hurricanes are defined as those reaching Category 3 or greater with winds of or exceeding 178 km/h. These estimates pertain to the formation of such tropical systems over the Atlantic Ocean and do not imply subsequent track or landfall. Track and landfall predictions depend on the concurrent state of the atmosphere and cannot be assessed reliably more than 7-10 days in advance.
This outlook is based on predictions of the main climate factors know to influence seasonal Atlantic hurricane activity and regional and global model predictions of atmospheric and oceanic conditions. The Atlantic Multi-decadal Oscillation (AMO) is considered a main climate factor that influences the Atlantic hurricane season as it sets the way to other climate phenomena such al El Nino or La Nina. The AMO is defined from sea-surface temperature (SST) patterns in the North Atlantic.
Given the current oceanic and atmospheric conditions in addition to the concurring forecasts of NOAA and CSU discussed above, there is a potential of 1 to 3 tropical/extratropical cyclones to affect Newfoundland and Labrador through the rest of this season with the highest impact expected to be along southern Newfoundland and Labrador"
Flooding is a natural event, but often has devastating effects on our lives and properties. These can be minimized by proper planning, state-of-the-art flood forecasting and flood alert systems and appropriate flood control strategies.
In Newfoundland and Labrador, floods in the fall of the year are the most costly in terms of flood damages.
Below is a graph with a seasonal breakdown of Disaster Financial Assistance Arrangements (DFAA) Damage Estimates. As illustrated, Fall events result in the greatest dollar value flood damages.
Total DFAA Flood Damage Estimates by Season from 2000-2010
|Season||Flood Damage Estimates ($)|
Flooding in the fall is typically caused by weather systems that originate as hurricanes. The damage path from hurricane based weather systems is typically widespread as was observed for Hurricane Igor in 2010.
Floods, public safety and climate change are integrally linked. Due to climate change, the frequency and intensity of extreme precipitation events such as hurricanes that result in flooding is expected to increase. Climate change altered precipitation patterns will result in new communities experiencing regular floods and communities with existing flooding issues experiencing more intense and extensive flooding incidents.
The Hurricane Season Flood Alert System (HSFAS) is based on forecasted precipitation amounts and seeks to provide communities with flood warning services as a key climate change adaptation and public safety tool.
Alerts are provided to communities that have Flood Risk Mapping Studies (FRMS) or have published intensity-duration-frequency (IDF) curves from which precipitation based flood triggers can be derived. The HSFAS is to help communities in the province prepare for storms and avoid future high-cost expenditures in repairs and damages.
The HSFAS is operational during the peak hurricane months of June to December.
The communities for which alerts are currently provided are listed in the Table below and depicted in the following map.
Communities / Areas with Precipitation Triggers for Hurricane Season Flood Alerts
|Precipitation-based flood triggers||1:20 (mm)||1:100 (mm)|
|2||Bishops Falls||Exploits River||60||78||75||99|
|3||Carbonear||Island Pond Brook, Powell's Brook||74||95||95||117|
|4||Great Codroy (Codroy Valley)||Grand Codroy River, South Branch||98||-||121||-|
|5||Cold Brook, Kippens (Gaudon's Brook)||Cold Brook, Gaudon's Brook||69||-||86||-|
|6||Corner Brook||Corner Brook Stream, Bell's Brook, Petrie's Brook||54||66||62||76|
|7||Deer Lake, Steady Brook (DEER LAKE A)||Deer Lake, Humber River||54||63||66||76|
|8||Glovertown||Terra Nova River||60||78||75||99|
|9||Petty Harbour, St. John's (Goulds)||Cochrane Pond Brook, Doyle's River, Raymond Brook, Third Pond, Petty Harbour River, Dirty Bridge River, Goulds Stream, Second Pond, Third Pond, Fourth Pond, Fourth Pond Brook||96||110||121||137|
|10||Mount Pearl, St. John's||Waterford River||77||91||95||111|
|11||Hant's Harbour||Halfway Brook, Short's Brook||74||95||95||117|
|12||Heart's Delight-Islington (Heart's Delight)||Heart's Delight Brook, Brook No. 1, Brook No. 2||74||95||95||117|
|13||Hickman's Harbour-Robinson Bight (Hickman's Harbour)||Tween Bridge Pond to harbour||-||85||-||115|
|14||Hodges Cove||tidal basin behind causeway||-||85||-||115|
|15||Logy Bay-Middle Cove-Outer Cove||Outer Cove, Coakers River, Drukens River, Kennedy's Brook, Outer Cover Brook||96||110||121||137|
|16||Portugal Cove-St. Philip's||Main River, Murray's Pond River, Broad Cove River||-||112||-||136|
|17||Salmon Cove||Salmon Cove River||74||95||95||117|
|18||Clarenville (Shoal Harbour)||Shoal Harour River||-||82||-||115|
|19||Stephenville||Noel's Pond, Warm Creek, Blanche Brook||79||105||102||136|
|20||Stephenville Crossing, Black Duck Siding||St. George's River, Harry's River||79||105||102||136|
|21||Bay Roberts (Shearstown)||Shearstown Brook||76||90||108||132|
|22||Trout River||Trout River||75||93||93||116|
|23||Victoria||Salmon Cover River||74||95||95||117|
|25||Winterton||Western Pond Brook||74||95||95||117|
|1||Argentia (ARGENTIA (AUT))||NA (IDF location)||141||153||198||210|
|2||Battle Harbour (BATTLE HARBOUR LOR)||NA (IDF location)||51||69||62||86|
|3||Burgeo (BURGEO NL)||NA (IDF location)||85||102||101||123|
|4||Churchill Falls||NA (IDF location)||44||52||55||64|
|5||Comfort Cove (COMFORT COVE)||NA (IDF location)||62||72||84||91|
|6||Daniel's Harbour (DANIELS HARBOUR)||NA (IDF location)||75||105||97||139|
|7||Gander (GANDER AIRPORT CS)||NA (IDF location)||61||77||76||98|
|8||Happy Valley-Goose Bay (GOOSE A)||NA (IDF location)||51||65||63||81|
|9||La Scie (LA SCIE)||NA (IDF location)||66||78||84||96|
|10||Mary's Harbour (MARY'S HARBOUR A )||NA (IDF location)||51||71||64||92|
|11||Nain (NAIN A)||NA (IDF location)||52||63||64||78|
|12||Channel-Port aux Basques (Port Aux Basques)||NA (IDF location)||92||115||133||145|
|13||St. Alban's (ST ALBANS)||NA (IDF location)||95||142||116||183|
|14||St. Anthony (ST ANTHONY)||NA (IDF location)||58||78||70||97|
|15||St. Lawrence (ST LAWRENCE)||NA (IDF location)||93||108||114||134|
|16||Wabush (WABUSH LAKE A)||NA (IDF location)||43||54||53||67|
Community Locations for Hurricane Season Flood Alerts
The HSFAS Alerts are based on site specific weather forecasts that are generated by AMEC Environment & Infrastructure as a result of examining many of the available models from Environment Canada, the US National Oceanic and Atmospheric Administration, and AMEC’s in-house implementation of the Weather and Research Forecast model. Examining maximum precipitation predictions from many different dynamic models allows AMEC Environment & Infrastructure to produce a better forecast of the maximum precipitation potential based on the strength of different models in handling the atmospheric physics of differing weather patterns. Furthermore, AMEC Environment & Infrastructure also examines the various model precipitation outputs within a given radius of each community/area. This allows AMEC Environment & Infrastructure to identify potential flood situations where a particular model may have accurately modeled precipitation amount or identified a flood situation but erred in the placement of its location.
These site specific precipitation forecasts are then directly linked to each site’s past flooding history through precipitation triggers. The precipitation triggers are derived from flood risk mapping studies and IDF curves. These precipitation triggers are summarized in Table 1.
The Water Resources Management Division correlates the HSFAS Alerts from AMEC Environment & Infrastructure with water flow rates in the province’s river systems. This information is sent to Fire and Emergency Services NL (FES-NL) who then alert the affected communities and coordinate responses.
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