Update #3 – September 28

Highlights from Environment Canada September weather bulletin

Following a record warm spring, summer 2016 was much closer to normal in terms of temperature with most of the region reporting slightly warmer than normal conditions.

  • The Interior of B.C. saw near normal rainfall this summer while the Coast and Southern Vancouver Island were significantly drier than normal.
  • The Kelowna weather station recorded one of its warmest Augusts on record.
  • The Okanagan Lake windstorm on August 21st was listed among the four “significant meteorological events” in B.C. this summer.

Hydrological Review by B.C. River Forecast Centre

A very warm spring season led to an early snow melt in B.C. This resulted in extremely low (<50% of normal) June 1st snow packs for most of B.C. Water supply forecasts indicated potential for earlier than normal summer low streamflow conditions and/or potential for very low streamflow conditions in some basins in southern B.C. The early melt and low snow pack also resulted in low magnitude peak flows for most of the major streams in the province. The Fraser River, for example, peaked in early May below the 2-year return period flow. This was one of the earliest peaks and lowest peak flows on record. Several streams in the Southern Interior experienced very low streamflows through August.

Fall Outlook 2016 (September-October-November)

Pacific sea surface temperatures (SST) off the coast of B.C. and much of the northeastern Pacific continue to be significantly warmer than normal. The large area of abnormally warm water that
appeared over the northeastern Pacific during the fall of 2014 and became known as “the Blob” returned this summer after a brief hiatus last spring. Seasonal forecast models are suggesting a
persistence of the warmer than normal waters and the associated Blob which inevitably contributes to a warmer than normal seasonal forecast. The most recent seasonal forecast issued on September 1st, 2016 indicates moderate chances (40-70%) of warmer than normal conditions through this fall.

El Niño conditions have finally returned to neutral for the first time since August 2014. Currently, the majority of seasonal forecast models indicate a borderline or a weak La Niña developing during the Northern Hemisphere fall and persisting through winter 2016-17. La Niña conditions only begin to affect our weather once we enter the winter season, and typically bring cooler and wetter conditions.

The forecast for neutral or weak La Niña conditions indicates a transition to cooler temperatures later this fall. However, the continued warm water of the B.C. coast may cause enhanced convective storm activity and higher intensity rain events for coastal B.C. This may result in flashy streamflow responses and rapidly developing flood events. At this time, it is unclear whether conditions this fall will be wetter than normal.