Ministry of FLNRO

Snow Survey and Water Supply Bulletin - February 1st, 2016

The February 1st snow survey is now complete. Data from 118 snow courses and 56 automated snow stations around the province and climate data from Environment Canada have been used to form the basis for the following report.

Click here for the Snow Survey and Water Supply Bulletin as a PDF file.
Click here for the complete February 1, 2016 Snow Survey Data.
Click here for the Basin Snow Water Index Map.

Weather
Weather through January was mixed, with dry periods, particularly in the beginning of the month, interspersed between more active storm cycles in the second half of the month. Overall, January temperatures were above normal across the province, with daily minimum temperatures being 3-5˚C above normal for many areas in south-east, central and northern BC. Temperatures in south-west BC were closer to normal, or slightly above normal.

January precipitation patterns have also varied across the province. South-west BC experienced near-normal to below-normal precipitation. Much of the rest of southern BC, including the southern Interior, Okanagan, Kootenay and Columbia, experienced above normal January precipitation. Central and northern BC experienced below to well-below normal precipitation.

Snowpack
Snow basin indices range from a low of 56% in the Stikine to a high of 122% in the Okanagan (Table 1). In general, most of the province has near normal or slightly below normal (80-110%) snow packs for February 1st, 2016, with a provincial average of 91% from all survey locations. A strong south to north gradient of snow pack levels exists, with normal or above normal snow pack in southern BC, lower than normal snow packs beginning in central BC, and extending to well below normal conditions in the north (Figure 1). Snow packs are below normal (70-80%) in the Upper Fraser West, Upper Fraser East, Nechako and Central Coast basins, and well below normal (<70%) in the Peace, Skeena-Nass, Stikine, and Liard basins. Above normal snow pack (>110%) is present in the Okanagan and Boundary.

Table 1:  BC Snow Basin Indices – February 1, 2016


Basin

% of Normal

Basin

% of Normal

Upper Fraser West

79

Boundary

114

Upper Fraser East

70

Similkameen

103

Nechako

80

South Coast

93

Middle Fraser

94

Vancouver Island

85

Lower Fraser

92

Central Coast

80

North Thompson

105

Skagit

64

South Thompson

102

Peace

66

Upper Columbia

102

Skeena-Nass

62

West Kootenay

101

Stikine

56

East Kootenay

99

Liard

64

Okanagan

122

Northwest

NO DATA

Outlook
Fall and early-winter has seen the dissipation of warm water in the northern Pacific Ocean (i.e. the “Blob”) which has been present over the past two winter seasons, and was likely the key driver in the very warm winters and extremely low snow packs that occurred in southern BC in 2014-15. Strong El Niño conditions that developed over the equatorial Pacific regions over the past few months have likely peaked, and are now declining. The Climate Prediction Centre (CPC) at the U.S. National Weather Service/NOAA is forecasting a high likelihood of El Niño conditions persisting through until late-spring or early summer 2016.

In general, BC experiences warmer than normal winter and early-spring temperatures during strong El Niño events. Precipitation during historic El Niño events has been highly variable, with no strong trends across BC. Snow packs during El Niño events tend to be slightly below normal across BC, however there has been significant historic variability and regional variation to this general trend. The effects of El Niño tend to be more pronounced during the mid- to late-winter and into spring. Snow and weather conditions so far this season have been typical for an El Niño year, with the exception of northern BC, which is experiencing lower snow pack than is typical. In southern BC, snow packs are much better developed than the extremely low conditions that were experienced last year.

Seasonal forecasts from Environment Canada are indicating a high likelihood of above-normal temperatures across British Columbia over the February to April period, and an increased chance of warmer than normal temperatures through the extended forecast period into the summer months. Seasonal forecasts from NOAA are suggesting a more southern path for the Pacific jet stream through the February-April period, with increased precipitation for California, and decreased precipitation for British Columbia and the Pacific Northwest. Seasonal precipitation forecasts tend to have much lower forecast skill than seasonal temperature forecasts, and therefore should be used with caution.

Seasonal volume runoff forecasts (see below) are near normal for most basins across the province. Below normal seasonal runoff is forecast in the Kalamalka-Wood basin, and well above normal in the Nicola River and Similkameen River systems.

By early February, nearly two-thirds of the annual BC snowpack has typically accumulated. At this stage in the season, there are two emerging snow pack trends of note. First is the higher than normal snow packs that are being observed in the Okanagan which are trending towards the potential for elevated seasonal flood risk. Localized areas with high snow pack, such as locations in the Nicola River system, may also be following this trend. The second trend is in well below normal snow packs in northern BC (Peace, Skeena, Stikine, Liard and to a lesser extent Upper Fraser basins). With these low snow packs, combined with the increased likelihood of a warmer than normal spring melt season, there is an increased chance of below normal stream flow, particularly in the late-spring and into summer.   

For both spring flood risk and summer low flows, snow pack is just one of the important elements that determine whether or not extreme conditions will emerge. Weather, through the remaining portion of the snow accumulation season, the melt season, and into the summer, is also a key driver on whether or not flooding or low streamflows will occur.

The River Forecast Centre will continue to monitor snow pack conditions and will provide an updated seasonal flood risk and stream flow forecast in the March 1st 2016 bulletin, which is scheduled for release on March 8th.

BC River Forecast Centre
February 9, 2016