Analysis: The Dalles water supply forecast reaches highest level of season, remains well above last year

The Dalles water supply forecast has continued to increase, reaching the highest level so far this season and 24% higher year on year on increased precipitation, according to Northwest River Forecast Center data.

The Dalles water supply forecast is currently at 106% of normal for the April-September season, 16 percentage points higher than a year ago, according to NRFC data, indicating a stronger forecast for hydro conditions during runoff season year on year. The forecast reached a high of nearly 109% on February 11.

The forecast has averaged 106% month to date, up from an average of nearly 100% in January, the January 2019 average of 90% and the February 2019 average of 89%, according to NRFC data.

Overall, January had above-normal precipitation for most river basins. Portland has received nearly 6 inches of precipitation month to date, 1.5 inches above normal, which followed January precipitation that was nearly 8 inches above normal at more than 18 inches, according to the US National Weather Service.

In comparison, January 2019 precipitation was 5.27 inches below normal, while February 2019 was 0.47 inches above normal, according to NWS data.

The three-month outlook probability indicates equal to above normal chances for precipitation across the Pacific Northwest region, according to NWS.

Power forward prices have trended down as the hydro forecast increased.

The Mid-C on-peak April package has averaged $13.36/MWh so far this month, down 20% month on month and down 49% from where the 2019 package averaged a year ago, according to S&P Global Platts data.

Mid-C on-peak May has averaged $11.29/MWh month to date, a decrease of 16% month on month and down 41% from the 2019 package average a year ago, while on-peak June has averaged $16.38/MWh, down 17% month on month and a drop of 38% from the 2019 package average last year at the same time.

Hydro output in January was up 19% month on month to average 201,213 MWh/day, while February's month-to-date hydro output is up nearly 27% month on month to average 254,714 MWh/d, according to Bonneville Power Administration data. In comparison, BPA hydro output decreased 1.4% month on month for December to average 169,332 MWh/d.

The Dalles power generation averaged 843 MW in January, up 18% from an average of 716 MW in December and up 7.4% from January 2019, according to US Army Corps of Engineers data.