- Today’s Hurricane Season Flood Alerts
- Current Streamflow Conditions
- Hurricane Season Forecast and Post-Season Reports
- Hurricanes, Flood Damages and Climate Change
- The Hurricane Season Flood Alert System
Today’s Hurricane Season Flood Alerts
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:
- An alert for “Areas with Flood Risk Mapping and Precipitation Induced Flooding” indicates a potential of flooding based on our flood risk mapping studies. The flood alerts are based on FRMS. All of the studies and mapping for the 1:20 and 1:100 AEP flood events are available on our Department’s webpage: www.mae.gov.nl.ca/waterres/flooding/frm.html. The studies defined the 1:20 and 1:100 Annual Exceedance Probability (AEP) flood event and associated precipitation events.
- An alert for “Areas with EC IDFs but no Flood Risk Mapping” is based on the IDF curves from Environment Canada for that specific area. Consequently, it does not reflect any historical flooding but indicates a historically rare event.
Today’s Hurricane Season Flood Alert (260 KB)
Current Streamflow Conditions
Existing conditions on rivers and lakes can impact whether a precipitation event leads to flooding. If water levels are already high the chance of a precipitation event leading to flooding will be increased. The map in the link below represents current streamflow conditions. The colored dots on this map depict streamflow conditions as a percentile, which is computed from the period of record for the current day of the year. Only stations with at least 20 years of record are used. A percentile is a value on a scale of one hundred that indicates the percent of a distribution that is equal to or below it. For example, on the map of daily streamflow conditions a river discharge at the 90th percentile is equal to or greater than 90 percent of the discharge values recorded on this day of the year during all years that measurements have been made. In general:
- a percentile greater than 75 is considered above normal
- a percentile between 25 and 75 is considered normal
- a percentile less than 25 is considered below normal
Hurricane Season Forecast and Post-Season Reports
The NOAA’s 2021 Atlantic Hurricane Seasonal Outlook predicts an above-normal season (60%), followed by a 30% chance of near-normal season and a 10% chance of a below-normal season. Colorado State University (CSU) predicts above-normal activity. It is worth noting that the NOAA uses a 30-year (1981-2010) based-climatology and the CSU has updated their 30-year climatology to include (1991-2020). Meanwhile, Tropical Storm Risk (TSR) predicts that the 2021 Atlantic hurricane season is expected to be 25-30% above the long-term (1950-2020) normal and 5-10% above the recent (2010-2020) ten-year normal.
Wood anticipates an above-normal Atlantic Hurricane season and a normal to slightly above-normal storm track across Atlantic Canada, specifically affecting Newfoundland and Labrador with extratropical storms. There is a moderate risk of a tropical storm and a low risk of a hurricane making landfall in Newfoundland.
Detailed Documents
- 2023
- 2022
- 2021
- 2020
- 2019
- 2018
- 2017
- 2016
- 2015
- 2014
Hurricanes, Flood Damages and Climate Change
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.
Season | Flood Damage Estimates ($) |
---|---|
Winter | $15,530,308 |
Summer | $15,589,602 |
Spring | $32,388,278 |
Fall | $101,014,638 |
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
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) | ||||
---|---|---|---|---|---|---|
# | Community (Area) | Watercourse | 12h | 24h | 12h | 24h |
FRMS | ||||||
1 | Appleton/Glenwood | Gander River | 60 | 78 | 75 | 99 |
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 | Happy Valley-Goose Bay (GOOSE A) | Otter Creek and Seven Other Creeks | 50 | 62 | 62 | 75 |
13 | Heart’s Delight-Islington (Heart’s Delight) | Heart’s Delight Brook, Brook No. 1, Brook No. 2 | 74 | 95 | 95 | 117 |
14 | Hickman’s Harbour-Robinson Bight (Hickman’s Harbour) | Tween Bridge Pond to harbour | – | 85 | – | 115 |
15 | Hodges Cove | tidal basin behind causeway | – | 85 | – | 115 |
16 | Logy Bay-Middle Cove-Outer Cove | Outer Cove, Coakers River, Drukens River, Kennedy’s Brook, Outer Cover Brook | 96 | 110 | 121 | 137 |
17 | Portugal Cove-St. Philip’s | Main River, Murray’s Pond River, Broad Cove River | – | 112 | – | 136 |
18 | Salmon Cove | Salmon Cove River | 74 | 95 | 95 | 117 |
19 | Clarenville (Shoal Harbour) | Shoal Harour River | – | 82 | – | 115 |
20 | Stephenville | Noel’s Pond, Warm Creek, Blanche Brook | 79 | 105 | 102 | 136 |
21 | Stephenville Crossing, Black Duck Siding | St. George’s River, Harry’s River | 79 | 105 | 102 | 136 |
22 | Bay Roberts (Shearstown) | Shearstown Brook | 76 | 90 | 108 | 132 |
23 | Trout River | Trout River | 75 | 93 | 93 | 116 |
24 | Victoria | Salmon Cover River | 74 | 95 | 95 | 117 |
25 | Whitbourne | Hodge River | 74 | 95 | 95 | 117 |
26 | Winterton | Western Pond Brook | 74 | 95 | 95 | 117 |
IDF | ||||||
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 | La Scie (LA SCIE) | NA (IDF location) | 66 | 78 | 84 | 96 |
9 | Mary’s Harbour (MARY’S HARBOUR A ) | NA (IDF location) | 51 | 71 | 64 | 92 |
10 | Nain (NAIN A) | NA (IDF location) | 52 | 63 | 64 | 78 |
11 | Channel-Port aux Basques (Port Aux Basques) | NA (IDF location) | 92 | 115 | 133 | 145 |
12 | St. Alban’s (ST ALBANS) | NA (IDF location) | 95 | 142 | 116 | 183 |
13 | St. Anthony (ST ANTHONY) | NA (IDF location) | 58 | 78 | 70 | 97 |
14 | St. Lawrence (ST LAWRENCE) | NA (IDF location) | 93 | 108 | 114 | 134 |
15 | Wabush (WABUSH LAKE A) | NA (IDF location) | 43 | 54 | 53 | 67 |
The HSFAS Alerts are based on site specific weather forecasts that are generated by Wood as a result of examining many of the available models from Environment Canada, the US National Oceanic and Atmospheric Administration, and WOOD’s in-house implementation of the Weather and Research Forecast model. Examining maximum precipitation predictions from many different dynamic models allows Wood 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, Wood also examines the various model precipitation outputs within a given radius of each community/area. This allows Wood 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 Wood with water flow rates in the province’s river systems. This information is sent to Emergency Services Division who then alert the affected communities and coordinate responses
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