Pacific Northwest DEWS Drought & Climate Outlook: February 22, 2021

Climate Recap and Current Conditions Summary

Speaker: Karin Bumbaco, Office of the Washington State Climatologist

• This water year remains on the warm side, despite the recent cold February.
• Water year precipitation is below normal in central Oregon and southern Idaho, and near normal to above normal in the rest of the region.
• Mountain snow greatly improved in recent weeks, but some areas are still below normal.
• The U.S. Drought Monitor continues to reflect the dry conditions of the 2020 water year and continued dryness during this water year.

Seasonal Conditions and Climate Outlook Summary

Speaker: Andy Bryant, National Weather Service Weather Forecast Office - Portland

• La Niña moderates to ENSO-neutral this summer.
• Temperatures: Below-average temperatures are likely for spring, and above-average likely for summer.
• Precipitation: Near to above-average precipitation is likely for spring, and below-average likely for summer.
• Mountain snowpack is likely to build through mid-spring.
• Drought is likely to persist for much of Oregon, southern Idaho, and parts of western Montana.
• Water supply forecasts are near to above-average in the north and below-average in the south.

Soil Management for Dry Farmed Vegetable Production

Speaker: Amy Garrett and Matthew Davis, Oregon State University

Big Takeaways for Farmers

• Diligent weed management is especially important for dry farmers!
• Don’t over-fertilize dry-farmed tomatoes. Too much fertility (from compost or nitrogen fertilizers) may result in increased BER.
• Dust mulching (6 to 8 inches) did not significantly increase yield or quality of dry-farmed tomatoes compared to surface cultivation (2 to 3 inches).
  • Weed management and surface protection.
  • Less soil disturbance can improve soil health over time.
• Leaf mulch had negative impact on dry-farmed tomato production.
  • This was only a one-year study,
  • Mulch was applied shortly after transplanting.
  • Two inches of rain fell after mulch was applied.
  • Multi-year studies and other mulches should be explored.

Winter Melt Trends Portend Widespread Declines in Snow Water Resources

Speaker: Keith Musselman, Institute for Arctic and Alpine Research, University of Colorado-Boulder

• Three times more stations have increasing winter snowmelt trends than snow water equivalent (SWE) declines.
• Winter melt trends are highly sensitive to temperature and an underlying warming signal, while SWE trends are more sensitive to precipitation variability, which has a weaker climate change signal.
• Recent stability of western U.S. SWE (since ~1980) will be followed by a period of accelerated decline once the current mode of natural climate variability subsides.
• More winter snowmelt will complicate future water resources planning and management efforts.
• We’re interested to hear what stakeholders are observing. How might more winter snowmelt affect operations?