Pacific Northwest DEWS Drought & Climate Outlook Webinar: December 19, 2022

Webinar Introduction

Speaker: Britt Parker, NOAA's National Integrated Drought Information System (NIDIS) and University of Colorado-Boulder/Cooperative Institute for Research in Environmental Sciences (CIRES)

• This bi-monthly webinar is co-hosted by NIDIS, the USDA Northwest Climate Hub, and the Oregon Climate Change Research Institute (OCCRI).
• Introduction of today's speakers:
  • Zach Hoylman, Montana Climate Office/University of Montana
  • Andrea Bair, National Weather Service Western Region
  • David Hoekema, Idaho Department of Water Resources
  • Karin Bumbaco, Office of the Washington State Climatologist/University of Washington
  • Larry O’Neill,  Oregon Climate Office/Oregon State University
• Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS)

Climate Recap & Current Conditions

Speaker: Zach Hoylman, Montana Climate Office/University of Montana

• Temperatures: It's been cooler than normal over the last 90 days across the south-central portions of the region, and warmer than average across the western portions.
  • The last 30 days have been well below normal across the entire region.
• Precipitation: 90-day precipitation conditions generally followed temperature—it has been drier than normal in the western portions and wetter than normal in the southeastern portions.
  • The last 30 days show a similar story.
• These conditions and recent deficits are contributing to:
  • Reduced soil moisture.
  • Reduced streamflow, especially along the Washington/Oregon Cascades.
  • However, snowpack is showing an encouraging start to the accumulation year! 

Seasonal Conditions & Climate Outlook

Speaker: Andrea Bair, National Weather Service Western Region

• This is the third consecutive winter in a row with La Niña conditions, which does not occur often when looking back at past events.
• La Niña is expected to continue into the winter, with equal chances of La Niña and ENSO-neutral during the January–March 2023 season. In February–April 2023, there is a 71% chance of ENSO-neutral.
• La Niña winters tend to bring cooler and wetter conditions to portions of the Pacific Northwest, but it is important to remember that no two La Niña winters result in exactly the same impacts.
• The January–March 2023 seasonal outlooks favor below-normal temperatures and above-normal precipitation for much of the northern Pacific Northwest, with drought improvement likely.

State Specific Conditions and Outlook Highlights as We Head Into Winter

Idaho

Speaker: David Hoekema, Idaho Department of Water Resources

• The Boise reservoir system is in good shape going into the winter. 
• The large reservoirs on the Snake River system are near empty and would need an estimated 120% of snowpack this winter in order to recover.
• The Snake River system is 1 million acre-feet short of normal, and this is representative of most of southern Idaho.
• When there have been consecutive La Niñas, they have tended to get drier for southern Idaho, so this is a concern going into the winter months—though it is impossible to predict how any La Niña year will play out. 

Washington

Speaker: Karin Bumbaco, Office of the Washington State Climatologist/University of Washington

• The recent temperature swing from the warm October to cold November in Washington was the largest temperature anomaly swing seen during fall going back to 1895. 
• While snowpack has generally been above normal so far for Washington (with the exception of the northern Cascades), we need about 150% of normal precipitation by April to recover from the drier-than-normal summer and fall. On the other hand, the Yakima basin reservoirs are currently near-normal. 
• The lack of fall rains didn't allow the soils to saturate, which could be problematic in the spring when our snowpack begins to melt. One example is Burnt Mountain on the west slopes of the Washington Cascades, which has much below normal soil moisture at 8-inch depth but above-normal snow water equivalent (SWE). 

Oregon

Speaker: Larry O’Neill, Oregon Climate Office/Oregon State University

• There is relatively little carryover in many of Oregon’s reservoirs into Water Year 2023.
• Much of the state has had a dry start to the water year.
• Despite the lack of precipitation thus far, consistently cool temperatures have fueled a good start to the seasonal snowpack across Oregon.
• Much of the state is experiencing very dry soil moisture conditions.

Conclusion and Q&A

Speaker: Britt Parker, NOAA/NIDIS; CU Boulder/CIRES

• Register now for the next webinar on February 27, 2023.