![](media/image1.jpeg){width="1.7798611111111111in"
height="1.3333333333333333in"}**Update on West-Wide Hydrologic
Forecasting at the University of Washington**

Alan Hamlet

Andy Wood, Dennis P. Lettenmaier

*Department of Civil and Environmental Engineering*

*University of Washington*

**1. Introduction: UW Experimental Hydrologic Forecasting System**

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height="2.3041666666666667in"}

This just describes the framework for simulations -- how the forecasts
are made.

Note that the update cycle is typically monthly, with forecasts
initialized on day 1 of the month, although we occasionally do twice
monthly forecasts if changing conditions warrant.

![](media/image3.png){width="3.2444444444444445in"
height="2.2847222222222223in"}

Here I typically say the system is implemented using VIC (wat/nrg
balance model, etc.), and the spinup simulation produces an initial
condition for snowpack and soil moisture over a domain of about 18,000
cells.

![](media/image4.png){width="3.3513888888888888in"
height="2.379166666666667in"}

Our framework has allowed the use of climate forecast information from a
number of sources -- ESP & derivatives, climate model (NCEP/NSIPP), and
CPC probabilistic outlooks. Currently we are re-implementing the climate
model forecasts, and the CPC forecast approach is also evolving as we
try to improve the temporal disaggregation step.

**2. Water Year 2006: Current Conditions and Outlook**

Now, we'll just show a few slides showing current conditions and the
streamflow outlook for this year.

![](media/image5.png){width="3.1930555555555555in"
height="2.3409722222222222in"}

SWE also reflect this reverse of moisture gradient -- last year was
record setting, both dry in NW and wet in the SW, whereas this year is
much nearer normal in the PNW, albeit with below avg snow at low
elevations, and below avg in the SW (particularly rio grande).

![](media/image6.png){width="3.35625in" height="2.4784722222222224in"}

This bubble plot shows the streamflow outlook for summer runoff for
about 90 locations in the domain. The anomalies are consistent with
those shown in the spatial plots, with the lowest outlooks for the SW
streams nearest that very low SM pattern we saw 2 slides back, and
normal outlooks in the PNW.

Note, this west-at-a-glance display, with both mouse-overs that show
various anomalies for the locations, and clickable points that launch
more details, is something we have only recently added.

**3. Current research activities:**

Now that we're talking about new features, we'll continue with a quick
summary of recent features or developments related to the west-wide
system.

-   Daily SWE observation west-wide roundup

-   Multi-model forecast approach

-   Daily nowcast update (from SW Monitor)

-   Interaction with NRCS Water & Climate Center

-   Basin-average water balance analyses

-   Pilot basin operational efforts

![](media/image7.png){width="3.1951388888888888in"
height="2.3847222222222224in"}

In addition to the streamflow hydrographs that we've had for a while,
the clickable streamflow map now brings up the current water year
conditions for P,T,SM,SWE, RO -- which are helpful in showing where we
are with respect to climatology. These are averaged over the drainage
basin contributing to streamflow at each location.

![](media/image8.png){width="3.1951388888888888in"
height="2.3930555555555557in"}

Another new feature is that we're now plotting up several analyses of
snow observations, and these update on a daily basis. We've been
automatically downloading the data for a long time for use in our
assimilation, and the goal here was to show the west-wide conditions at
a single glance, something that's hard to find elsewhere.

Note, in addition to the NRCS snotel points, we also have the California
DWR snow pillows, and the Env. Canada snow pillows in the Columbia R.
drainage.

There are about 5 plots -- some of which are for changes during the last
week or two.

![](media/image9.png){width="3.1930555555555555in"
height="2.307638888888889in"}

Another effort is related to evaluating a multi-model land surface
ensemble. One of the conclusions of the LDAS initiative is that there
might be some value to running algorithms from a number of models -- see
quote.

![](media/image10.png){width="3.198611111111111in"
height="2.295138888888889in"}

This is the test case in Idaho

![](media/image11.png){width="3.1993055555555556in"
height="1.7229166666666667in"}

Here are the long term average results for the 3 models, none of which
have been extensively calibrated. VIC is best, although the SAC model is
not bad. The NOAH model has real problems with its snow simulation.

![](media/image12.png){width="3.1951388888888888in"
height="1.7868055555555555in"}

This is the result from a validation period for an ensemble combination
of a single run of the each model. It's clear that the model averaging
process greatly reduces the error in the long term mean error & RMSE.

![](media/image13.png){width="3.19375in" height="2.370833333333333in"}

Another area of current research relates to the surface water monitor
developed last year by A. Wood. This system, applied at coarse (1/2
degree) resolution over the entire CONUS, is completely automated
(free-running) and updates every day. It's just a prototype, demo
project that have been unable to get funding to extend, and the main
products are maps of current soil moisture & SWE, and an monthly archive
that extends back to 1915, that also has SM & SWE maps.

Anyway, we are now adapting the daily update approach for use in the
westwide forecast system, and should have the first basin (PNW) land
surface conditions updating daily (at 1/8 degree) within the month.
After that we'll move on to other basins, and probably extend the 1/8
nowcast eastward to the Mississippi R.

**Current Activities:** Interaction with NRCS NWCC

**Since last year, we have exchanged nowcast / forecast results with the
NRCS National Water and Climate Center (head: Phil Pasteris)**

-   Under a Memorandum of Understanding between NRCS & UW:

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-   UW provides forecast results and data as NRCS requests

-   NRCS provides access to stream flow and climate data (primarily via
    NOAA ACIS)

-   NRCS has created a place for links to "experimental water supply
    forecasts" from its official website. ***Currently the UW is the
    only one, and they would like more!***

-   We generally attempt to schedule a "pre-forecast" conference call
    just prior to NRCS coordination of forecasts with NWS RFCs, in which
    we summarize our forecast outlooks and compare notes.

-   In addition, there is a fair amount of informal exchange.

We also have an on-going interaction with the NWCC, and exchange results
and comments on a routine basis during the forecast season. Credit Phil
Pasteris, Tom Pagano, Tom Perkins, Jolyne Lea.

Note that NWCC is experimenting with a modeling capability based on the
USGS PRMS model.

![](media/image14.png){width="3.1930555555555555in"
height="2.379861111111111in"}

These are just the domains of the studies -- for some of this 4 state
area, we're moving to a 1/16 of a degree resolution because the forecast
points have smaller drainage areas than we're comfortable with at 1/8
degree.

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height="1.8194444444444444in"}

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