Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Tracking an Uncertain Climatefor Water Supply

Phillip Pasteris

Natural Resources Conservation Service

National Water and Climate Center

Portland, Oregonwww.wcc.nrcs.usda.gov

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

WY-2001 - One for the Books!

• Lowest Columbia streamflow since 1977

• Lowest snowpacks since 1977

• Record peak power prices

• Record drought in many areas

• Significant forest fires in CA, WA, MT

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

The Dalles Hydrograph

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Columbia Snowpack

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Columbia Snowpack

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Record Drought

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

WY-2002 - Uncertainty

• Summary provided by George Taylor, Oregon State Climatologist - www.ocs.orst.edu

• National Centers for Environmental Prediction (NCEP) coupled ocean/atmosphere model shows a weak El Nino developing in the next six months.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

WY-2002 - Uncertainty

• The Scripps / Max Planck Institute (MPI) hybrid coupled model include a moderate El Nino developing this fall, followed by a return to near-normal conditions in mid-winter.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

WY-2002 - Uncertainty

• The Climate Diagnostics Center (CDC) predictive model takes a contrary viewpoint, indicating the development of much stronger La Nina conditions in the next several months, continuing throughout the winter.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

WY- 2002 - Where Are We Now?

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

WY- 2002 - Tracking Uncertainty

• Real-time climate data from SNOTEL

• Real-time climate data from BC network

• NWS COOP climate data through UCAN

• Streamflow from the USGS

• Reservoir data from operators

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

The SNOTEL Network - OR

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

The SNOTEL Network - WA

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

The SNOTEL Network - ID

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

The SNOTEL Network - MT

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Snow Network in BC

http://www.elp.gov.bc.ca/rib/wat/rfc/river_forecast/spdcolumbia.html

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Snow Plots In British Columbia

Molson Creek - Upper Columbia

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Snow Plots In British Columbia

East Creek - W. Kootenay R.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Snow Plots In British Columbia

Morrissey Ridge - E. Kootenay R.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Typical SNOTEL Data Plot

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Typical SNOTEL Data Plot

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Typical SNOTEL Data Plot

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Typical SNOTEL Data Plot

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Typical SNOTEL Data Plot

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Sub-Monthly Water Supply Forecasts

• Production of sub-monthly water supply forecasts (WSFs) is driven by user needs for more frequent assessments of water supply availability based on real-time SNOTEL information.

• Users include NRCS Water Supply Specialists; private, state, and federal reservoir owners/operators; dam safety engineers and hydrologists; Montana Fish Wildlife and Parks; Montana Power; irrigation companies; and NRCS field offices that distribute our streamflow forecasts to local irrigators, reservoir operators, and conservation district boards.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Sub-Monthly Water Supply Forecasts

• The concept is to “capture the trend” using daily SNOTEL data and provide users with more frequent forecasts that reduce risk.

• Because the WSF procedures selected for this process primarily use SNOTEL data, we can use the current SNOTEL observations and project forward to the 1st of the month.

• The only "unknown" in these procedures is the next month's SNOTEL snow water equivalent value; the only other data in these procedures (until June 1) is fall precipitation, which is already known.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Sub-Monthly Water Supply Forecasts

• Flat-line scenario:

• We can simply take the value from SNOTEL today and use it as is, thus assuming no additional accumulation for the rest of the month.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Sub-Monthly Water Supply Forecasts

• Add/subtract some portion of a normal (average) increment:

• If we think the precipitation during the remaining period of the month is going to be below normal, then we could add, say, 75% of a normal increase (prorated for the days left until the first of the month) to the current observed value.

• Likewise, we could add, say, 125% of the normal increase if we saw that the weather forecasts called for major storms in the coming days or weeks.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Sub-Monthly Water Supply Forecasts

• Use the same rate of change that has occurred so far this month.

• For example, if the February 1 snow water equivalent was 10" and the value on February 22 was 12", that is a 2" increase over the first 22 days of the month, or 2/22 = or 0.0909" per day.

• The process would then add 0.0909 * 7 (days left in the month [leap year]) = 0.6 to obtain 12.6" as the estimated value for March 1.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

Preliminary Results

• Montana responses were very favorable.• Recognized the deteriorating snowpack

conditions.• Captured the trend on a weekly basis.• Provided opportunities to ingest late season

snowfalls and reduce hope for drought reduction.

• Further analysis underway.

Long-range Forecasting of Climate and Water Resources in the Pacific Northwest , October 2001, Kelso, WA

In Summary

• Climate trends and variability are something we need to learn to live with.

• Using climate networks, like SNOTEL, on a daily basis helps all resource managers and the public cope.

• “The future ain’t what it used to be.” - Yogi Berra