BOARD01836

• Board Meeting Date: 3/22/2005
• Description: Flood Section - Report on the CWCB Enhanced Snowpack Assessment Project for Water Year 2004-2005
• Board Meetings - Doc Type: Memo

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STATE OF COLORADO

. Colorado Water Conservation Board

Department of Natural Resources
1313 Sherman Street, Room 721
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
www.cwcb.state.co.us

MEMORANDUM

Bill Owens
Governor

Date:
Re:

Colorado Water Conservation Board Members
Larry Lang, Chief, Flood Protection Program
Joe Busto, Flood Protection Program & Weather Modification Program
Michelle Garrison, Water Supply Protection Program
March 14, 2005
Agenda Item 23- Report on the CWCB Enhanced Snowpack Assessment
Project for Water Year 2004-2005

Russell George
Executive Director

To:
From:

Rod Kuharich
CWCB Director

Dan McAuliffe
Deputy Director

Background
CWCB staff and the USBR River Systems & Meteorology Group presented an overview ofthe Enhanced
Snowpack Assessment Project (project) at the January 2005 CWCB Meeting in Denver. The major
features ofthe Project are: SNODAS (modeled snowpack on llan grid), QPE-SUMS (Bureau's
precipitation accumulation algorithm), and in Phase III linking SNODAS to a hydrologic model to
produce streamflow forecasts for the State of Colorado (model yet to be chosen). The Project Managers
. are Steve Hunter-USBR and Michelle Garrison and Joe Busto-CWCB.

The April I snowpack is key for decision makers. The significant snowpack in southwestern Colorado is
prompting flooding concerns. The snowpack in the northern and eastern parts of the state remains near or
below average, making water storage a priority issue. CWCB staff and Steve Hunter will present the
SNODAS modeling results for Colorado's 2004-2005 snowpack.

SNODAS
The Snow Data Assimilation System (SNODAS) is a recent model operated by the National Operational
Hydrologic Remote Sensing Center (NOHRSC). The input components of SNODAS include:
. SNOTEL and snow course data
. satellite data
. radar data
. numerical weather model (incorporating gridded solar radiation, air temperature, relative
humidity, and wind speed)
The model is physically scaled to 1 Ian resolution using multiple atmospheric layers and a digital
elevation model.

Outputs from the SNODAS model include:
. snow depth
. snow water equivalent (SWE)
. snowpack temperature
. snowmelt at base of snowpack
. sublimation

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Colorado Water Conservation Board
Flood Protection. Water Supply Planning and Finance. Stream and Lake Protection
Water Supply Protection. Conservation and Drought Planning