Hydrologic Predictability and Water Year 2009 Predictions in the Columbia River Basin
Andy Wood
Matt WileyBart Nijssen
Climate and Water Resource Forecasts for the 2009 Water YearUW Climate Impacts Group
October 2, 2008, Vancouver, WA
Presentation Outline
1. Introduction
2. Current Conditions
3. Predictability in the Columbia R. Basin
4. Climate Predictions
5. Water Year 2009 Streamflow Outlook
Average annual water cycle
The PNW hydrologic cycle
PNW
* Where we are now on average
soil moisture near annual low
runoff near low
nearly all water year precipitation yet to come
snow season not really underway
evaporation waning
Hydrologic Model-based Forecasting
ICs*Spin-up Forecast
obs
recently observedmeteorological data
ensemble of met. datato generate forecast
hydrologicstate
IC = initial conditions
ENSO subset
196019611962……
1999
ESP
Can adjust IC by assimilatingsnow or other observations
a forecast hastwo key elements- initial conditions- climate forecast
Werner et al. (2003) weightingscheme for tracesrather than a subset
Initial Conditions – Soil Moisture
Soil Moisture Projections
Soil Moisture Projections
Current Soil Moisture Conditions
Is it dry in the Columbia R. Basin? Last year’s snowpack was good to great, but wasbased on normal or below precipitation in places
USDA/NRCS
Then, late summer was fairly dry…
Is it dry in the Columbia R. Basin?
What do the streamflows say? ID
What do the streamflows say? BC
What do the streamflows say? BC
What do the streamflows say? BC
What do the streamflows say? BC
What do the streamflows say? BC
What do the streamflows say? BC
But how much do ICs matter in Fall? 3TIER was recently funded by NOAA (SBIR) to run a massive set
of ensemble hindcasts.
56 years (1949-2005) of 56-member ESP forecasts for 72 locations in the PNW
archived streamflow, climate and water balance variables at a daily timestep
1-year lead time forecasts
6 start dates: 1st day of Nov, Dec, Jan, Feb, Mar, Apr
Many applications: measure model-based prediction skill calculate forecast corrections
Nov. 1Forecast
For every combination of historical IC with met. forecast…
what fraction of normal runoff was produced?
driest obs IC + driest met year
wettest obs IC +wettest met year
Nov. 1Forecast
Early in the water year,
wet IC adds < 10% dry IC removes < 10%
from April-July flow forecast
Dec. 1Forecast
As water year progresses, ICs become more importantprecip forecasts less important
Jan. 1Forecast
By January 1, knowing ICs is becoming as important as knowing future climate, for Apr-July flow prediction
Feb. 1Forecast
In February – April, the shift to the dominance of ICs (snow and soil moisture) progresses.
Mar. 1Forecast
In February – April, the shift to the dominance of ICs (snow and soil moisture) progresses.
Apr. 1Forecast
On April 1, the difference between the wettest & driest Spring met for forecast Apr-Jul flow is minor.
Given average precipitation in October, where will The Dalles forecast be on Nov. 1this year?
Climate Prediction
THIS YEAR
2008 La Nina versus Normal conditions: Oct-Dec
oct
nov
dec
precip temperature SWE soil moist runoff
2008 La Nina versus Normal conditions: Jan-Mar
jan
feb
mar
precip temperature SWE soil moist runoff
2008 La Nina versus Normal conditions: Apr-Jun
apr
may
jun
precip temperature SWE soil moist runoff
http://iri.columbia.edu/climate/ENSO/currentinfo/figure3.html
Current ENSO Forecasts…
….mostly point toward a neutral winter:
http://www.cdc.noaa.gov/people/klaus.wolter/MEI/
Yet a few are turning toward La Nina…
US and Europe agree on something?
NCEP
ECMWF
A number of forecasts update within the next week – worth checking at:
http://iri.columbia.edu/climate/ENSO/currentinfo/modelviews.html
Where NOAA fears to tread…
http://www.almanac.com/weather/index.php
Water Year 2009 Forecasts
2009 Natural Runoff Volume Forecasts
Columbia River at Mica Dam
percent of normal (‘71-’00) for period
Jan-Jul Apr-Jul Apr-Sep
97 97 98
2009 Natural Runoff Volume Forecasts
Pend Oreille River at Albeni Falls Dam
percent of normal (‘71-’00) for period
Jan-Jul Apr-Jul Apr-Sep
99 99 99
2009 Natural Runoff Volume Forecasts
Columbia River at Grand Coulee Dam
percent of normal (‘71-’00) for period
Jan-Jul Apr-Jul Apr-Sep
97 97 97
2009 Natural Runoff Volume Forecasts
Snake River below Lower Granite Dam
percent of normal (‘71-’00) for period
Jan-Jul Apr-Jul Apr-Sep
89 89 90
2009 Natural Runoff Volume Forecasts
Columbia River at The Dalles, OR
percent of normal (‘71-’00) for period
Jan-Jul Apr-Jul Apr-Sep
95 95 95
percent of normal (71-00) for period
Name Jan-Jul Apr-Jul Apr-Sep
Columbia River at The Dalles, OR 95 95 95
Columbia River at Grand Coulee Dam 97 97 97
Snake River below Lower Granite Dam 89 89 90
Pend Oreille River at Albeni Falls Dam 99 99 99
Columbia River at Mica Dam 97 97 98
2009 Natural Runoff Volume Forecasts Summary
questions?awood @ 3tiergroup.com
thank you!