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Snow Survey Bulletin
Snowpack and Water Supply Outlook for British
Columbia
June 15, 2008
Every
effort is made to ensure that data reported on these
pages are accurate. However, in order to update the graphs
and indices as quickly as possible, some data may have
been estimated. Please note that data provided on these
pages are preliminary and subject to revision on review.
The June 15th snow survey is now complete.
Data from 5 snow courses and 56 snow pillows around the province
have been used to form the basis for the following reports.
This is the final Snow Survey Bulletin for the 2007/08
snow season.
Snowpack
The 2008 spring snowmelt is well
advanced. The snow water indices for most basins are above
normal for the date, reflecting the cool spring weather and
slow melt. In most areas, low and mid elevation snow is gone,
and approximately one-quarter to one-half of the high elevation
snow remains to melt. The largest amount of snow still being
recorded is on Vancouver Island (snow water index = 1090 mm,
151% of normal) and the South Coast (index = 852 mm, 121%
of normal). High elevation portions of the Thompson and Columbia
still retain about one-half of their peak late winter snow.
Weather
Weather over the past three weeks
has been dominated by a series of weak frontal systems moving
off the Pacific and through the province. Weather has been
consistently cool and damp. Precipitation has generally been
near normal for most of the province, with the north-east
corner (e.g., the Liard basin) being notably wetter than normal.
Temperatures have been near or slightly below normal. The
cool weather has allowed snowmelt to proceed in a subdued
and orderly manner.
Most mainstem rivers in the province experienced
their freshet peak flows in late May or early June. Since
then, most rivers have been receding. Rainfall during late
May and early June has moderated the flow recession in some
areas.
Rapid snowmelt during a hot period in mid-May
produced high flows (in the 2-5 year return period range)
in small and mid-sized rivers in portions of the Interior
(South Thompson, Nicola, mid-Fraser, Upper Fraser, elsewhere).
No significant flooding (in the 20+ year return period range)
occurred this spring.
Most gauged rivers in the province are near
or above median flows for mid-June.
Outlook
There are no water supply issues
for the province evident at this time.
June 15
The upper Fraser snow index is 116% of normal at June 15,
with about 30% of high elevation snow remaining to melt. The
Nechako index is 68% of normal, with about one-quarter of
high elevation snow left to melt.
Precipitation in the Upper Fraser was near normal for May
and early June.
The Fraser River at Shelley (at Prince George)
peaked on May 22, near 4300 cubic metres per second..
Hydrograph of the Fraser River at Shelley
June 15
Snow water equivalencies throughout the Middle Fraser are
very low, with all the plateau snow melted completely. For
the Lower Fraser, the June 15 index is 108% of normal, with
about one-half of the high elevation snow remaining to melt.
The Fraser River at Hope experienced a peak
discharge near 10,200 on May 25. Flows are currently receding,
and are near normal for mid-June.
Hydrograph of the Fraser River at Hope
June 15
The North Thompson snow water index is 117% of normal for
June 15. Low and mid elevation snow has melted off. The South
Thompson snow water index is at 121%. In both basins, about
one-half of high elevation snow remains to melt.
The North Thompson River at McLure peaked
on May 22 at 1920 cms, while the Thompson River near Spences
Bridge peaked on May 25 at 2720 cms. They are currently receding
and are near normal for the date.
Hydrograph of
the North Thompson River at McLure
Hydrograph of the Thompson River near Spence's Bridge
June 15
Relatively very few snow surveys are conducted in the Columbia
basin at this sampling date. Based on the limited sample,
snowpacks in Columbia are near 50% of normal.
Streamflows in the region, as represented
by the mean monthly flow in the Columbia River at Donald,
are currently receding, after experiencing their freshet peaks
in early June.
Hydrograph
of the Columbia River at Donald
June 15
Based on a limited sample, the Kootenay snow
water index is 88% of normal on June 15. All low and mid elevation
snow throughout the Kootenays is gone, with about one-third
of the peak high elevation snow remaining.
Most rivers throughout the West and East Kootenay
experienced high flows in late May. No significant flooding
occurred this spring.
.
June 15
Most snow in the Okanagan, Kettle and Similkameen has melted,
and most areas are snow free, with the exception of remnant
patches at high elevation.
Small streams in the Okanagan basin experienced
their high flows in mid-May, and are now receding. They are
generally near seasonally normal discharge levels for mid-June.
The Similkameen, Tulameen and Kettle rivers
experienced their freshet peak flows in mid-May. They are
currently slightly near normal for mid-June.
Hydrograph
of the Similkameen River near Hedley
June 15
Vancouver Island and the South Coast continue with significant
high elevation snow. The Vancouver Island index is 151%
of normal, while the South Coast index is 121%. About one-half
of high elevation snow remains to melt.
May and the first half of
June were cool and damp throughout the coast. The rain and
continuing snowmelt have maintained streamflows at above normal
levels as of mid-June, and provides a positive outlook for
summer streamflows.
June 15
Based on a limited survey, the Peace River basin snow index
is 151% of normal for June 15, with about one-third of high
elevation snow remaining to melt.
June 15
The Skeena/Nass basin snow water index almost snow free, with
just a portion of high elevation snow remaining to melt.
Regional stream flows, as
reflected by the mean monthly flows in the Skeena River at
Usk, were above normal during early June. The Skeena River
experienced a freshet peak of 4950 cms on May 28.
Hydrograph for
the Skeena River at Usk
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