Ministry of Environment
Current Snow Survey and Water Supply Bulletin
The January 1st, 2012 snow survey is now complete. Data from 99 snow courses and 51 snow pillows around the province and out-of-province sampling locations, and climate data from Environment Canada, have been used to form the basis for the following reports.
The entire document including text and data can be viewed as an Adobe pdf file.
The detailed snow survey data can be viewed as an Excel file or PDF file.
Weather
Weather across British Columbia on average was near normal for October and November. December was drier than normal and 1-3 ̊C warmer than normal across the province. However, persistent high pressure ridging, particularly in the southern portion of the province, led to a fairly distinct difference in seasonal weather between the north half and south half of the province. The combination of high pressure in the south and low pressure systems off the Gulf of Alaska created a more northerly flow to the movement of Pacific storm systems. This led to much wetter than normal conditions in the north, and drier than normal conditions in the south. The breakdown of the high pressure ridging in mid-December brought the return of a more southerly track to storm systems, and more typical seasonal weather patterns to southern British Columbia.
Snowpack
Basin snow water indices across British Columbia reflect the seasonal weather pattern of wetter conditions in the north and drier conditions in the south. Basin indices are above normal through the Upper Fraser, Nechako, Middle Fraser, North Thompson, Columbia, Skeena-Nass and Peace, with a high of 170% of normal in the Upper Fraser basin. Snow basin indices for the southern portion of the province is normal through the south and south-east (Similkameen, Kootenay) and below normal through most of the south Interior (Okanagan-Kettle, South Thompson) and south-west (Lower Fraser, South Coast, Vancouver Island). The lowest observed snow basin index is 77% of normal for the Lower Fraser.
BC Snow Basin Indices – January 1, 2012
Basin |
% of Normal |
Basin |
% of Normal |
Upper Fraser |
170% |
Kootenay |
101% |
Nechako |
124% |
Okanagan-Kettle |
72% |
Middle Fraser |
114% |
Similkameen |
107% |
Lower Fraser |
77% |
South Coast |
82% |
North Thompson |
109% |
Vancouver Island |
88% |
South Thompson |
80% |
Peace |
147% |
Columbia |
117% |
Skeena-Nass |
137% |
Outlook
Last year’s snow season was influenced by a strong La Niña event (cooler than normal sea surface temperatures in the equatorial Pacific Ocean), which may have contributed to higher than normal snow packs, a cool spring, and a delayed and prolonged snow melt season. La Niña conditions have re-emerged over the past few months. The Climate Prediction Centre with the U.S. National Weather Service (NOAA) is predicting a weak to moderate La Niña event to persist into the spring of this year. In combination with La Niña, cool-phase Pacific Decadal Oscillation (PDO) conditions are present in the north-west Pacific with cooler than normal temperatures in the Gulf of Alaska. In-phase La Niña and PDO conditions tend to enhance seasonal climate effects. Current seasonal weather forecasts from Environment Canada are similar to what would be expected under La Niña and cool-phase PDO conditions, with cooler than normal and normal to wetter than normal conditions throughout most of British Columbia. Temperature anomaly outlooks tend to have greater forecast skill than precipitation anomaly outlooks.
By this date, generally about one-half of the annual BC snowpack has accumulated, with another 3 or more months of accumulation still to come. At this stage the two main issues in snow pack are the below-normal snow packs in the south Interior and south-west BC (and the potential for water supply issues into the summer of 2012), and the above-normal snow packs in the Upper Fraser, Peace and Skeena-Nass regions (and potential for increased spring flood risk). The current seasonal climate outlook is favourable for the development of above-normal snow packs through most of the province. This would assist in further developing the snow pack in regions that are currently below-normal, but may exacerbate snow pack in areas that are currently above-normal. It is currently too early in the snow accumulation season to be able to predict snow pack evolution over the remainder of the season with a high degree of certainty. The development of the snow pack through January and February will give a clearer picture on how these potential concerns evolve.
The next snow bulletin, for the month of January, will be available on or after February 7, 2012.
Produced by: BC River Forecast Centre
January 9, 2012
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