2026-02-21 Spring Diatom Bloom Forecast
The current best estimate of the first spring diatom bloom in the Strait of Georgia is 2026-03-19. That estimate is based on a run of the SOG biophysical model for deep estuaries [1] with the following parameters:
- Run start date/time: 2025-09-19
- Actual wind, meteorological, and river flow forcing data to 2026-02-20, and historical data from 1990 thereafter
1990 has the median bloom date in an ensemble of SOG runs that use historical wind, meteorological, and river flow data from 1980 through 2010 as future forcing data after 2026-02-20.
Best estimate bounds on the bloom date are:
- No earlier than 2026-03-08 based on using actual forcing data to 2026-02-20, and data from 2004/2005 thereafter. 2005 has the 5th centile bloom date in the ensemble of SOG runs.
- No later than 2026-04-07 based on using actual forcing data to 2026-02-20, and data from 2008/2009 thereafter. 2009 has the 95th centile bloom date in the ensemble of SOG runs.
[1] Allen, S. E. and M. A. Wolfe. (2013). Hindcast of the Timing of the Spring Phytoplankton Bloom in the Strait of Georgia, 1968-2010. Progress in Oceanography, volume 115, pp 6-13. https://dx.doi.org/10.1016/j.pocean.2013.05.026
Data Sources
The forcing data used to drive the SOG model is obtained from several sources:
- Hourly wind velocities at Sand Heads Lightstation from the historical data web service at climate.weather.gc.ca/ Hourly air temperature, relative humidity, and weather description (from which cloud fraction is calculated) at Vancouver International Airport (YVR) from the historical data web service at climate.weather.gc.ca/
- Average daily river discharge rates for the Fraser River, and the Englishman River (as a proxy for the fresh water sources other than the Fraser) from wateroffice.ec.gc.ca
Disclaimer
This site presents output from a research project. Results are not expected to be a robust prediction of the timing of the spring bloom. At this point, we believe such a prediction is not possible before mid-February using any model and this model is not yet tested.
Time Series
Profiles at 2026-02-20 12:00 from Median Prediction
Bloom Date Evolution
| Actual to Ensemble Forcing Transition Date | Median | 5th Centile Early Bound | 95th Centile Late Bound | Earliest Ensemble Result | Latest Ensemble Result | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Bloom Date | Ensemble Member | Bloom Date | Ensemble Member | Bloom Date | Ensemble Member | Bloom Date | Ensemble Member | Bloom Date | Ensemble Member | |
| 2026-02-20 | 2026-03-19 | 1990 | 2026-03-08 | 2005 | 2026-04-07 | 2009 | 2026-03-08 | 2005 | 2026-04-14 | 1999 |
| 2026-02-19 | 2026-03-19 | 1983 | 2026-03-08 | 2001 | 2026-04-07 | 2009 | 2026-03-07 | 2005 | 2026-04-14 | 1999 |
| 2026-02-18 | 2026-03-20 | 1990 | 2026-03-08 | 2001 | 2026-04-07 | 2009 | 2026-03-07 | 2005 | 2026-04-14 | 1999 |
| 2026-02-17 | 2026-03-20 | 1983 | 2026-03-08 | 2001 | 2026-04-07 | 2009 | 2026-03-04 | 2005 | 2026-04-14 | 1999 |
| 2026-02-16 | 2026-03-20 | 1983 | 2026-03-08 | 2001 | 2026-04-07 | 2009 | 2026-03-04 | 2005 | 2026-04-14 | 1999 |
| 2026-02-15 | 2026-03-20 | 1983 | 2026-03-08 | 2008 | 2026-04-07 | 2009 | 2026-03-04 | 2005 | 2026-04-14 | 1999 |
| 2026-02-14 | 2026-03-20 | 1990 | 2026-03-08 | 2001 | 2026-04-07 | 2009 | 2026-03-04 | 2005 | 2026-04-14 | 1999 |