Analysis from COOP daily precipitation
observations.
-Each site uses at least 30 years of data
-The top 10 daily precip dates are found
-The season for which most of these
top-10 dates occurred at that site is
color coded.
-The affect of the southwest Monsoon
is seen in yellow dots in AZ, CA, UT,
NM, and CO (yellow sites in the Great
Plains are not monsoon dominated)
-The affect of atmospheric rivers is
highlighted by blue and red dots,
including almost all of each coastal
state, plus inland penetration of AR
impacts into AZ, Western CO, SW and
Central UT, and ID.
-Great Plains convective events focus in
spring (light blue dots) and summer
(yellow).
-Colorado front range is mostly spring.
-Nevada is a mixture.
Seasonality of Annual Peak Streamflow
Seasonality of annual peak
daily stream flows highlighting
the preponderance of ARdominated regions (blue dots)
and Spring-melt dominated
regions (red dots in mountains)
Spring-Summer snowmelt
Atmospheric rivers
Fall-Winter
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Team Contributing to The “Western Obs’ Vision”
M. Ralph1, M. Dettinger2, A. White1, D. Reynolds3, D. Cayan2,
T. Schneider4, R. Cifelli5, K. Redmond6, M. Anderson7, F. Gherke7,
K. Mahoney8, L. Johnson1, S. Gutman9, V. Chandrasekar10, A. Rost11,
J. Lundquist12, N. Molotch13, L. Brekke14, R. Pulwarty15, J. Horel16,
L. Schick17, A. Edman18, P. Mote19, J. Abatzoglou20, R. Pierce21, G. Wick1
1NOAA/Earth
System Research Laboratory/Physical Sciences
Division, Boulder, CO
2U.S. Geological Survey, Scripps Institution of Oceanography, La
Jolla, CA
3NOAA/National Weather Service/Monterey Weather Forecast
Office, Monterey, CA
4NOAA/NWS/Office of Hydrologic Development, Boulder,
Colorado
5Cooperative Institute for Research in the Atmosphere, Fort
Collins, CO
6NOAA/Western Region Climate Center, Reno NV
7California Department of Water Resources, Sacramento, CA
8Cooperative Institute for Research in Environmental Sciences,
Boulder, CO
9NOAA/Earth System Research Laboratory/Global Systems
Division, Boulder, CO
10Colorado State University, Department of Electrical and
Computer Engineering, Fort Collins, CO
11NOAA/NWS/
National Operational Hydrologic Remote Sensing
Center, Chanhassen, MN
12University of Washington/Dept. of Civil and Environmental
Engineering, Seattle, WA
13University of Colorado at Boulder, Geography Department,
Boulder, CO
14U.S. Bureau of Reclamation, Technical Services Center, Denver,
CO
15NOAA/OAR/Climate Program Office, Physical Sciences Division,
Boulder, CO
16University of Utah, Department of Meteorology, Salt Lake City,
UT
17.S. Army Corps of Engineers, Seattle, WA
18NOAA/NWS Western Region Headquarters, Salt Lake City, UT
19Oregon State University, Oregon Climate Change Research
Institute, Corvallis, OR
20University of Idaho, Department of Geography, Moscow, ID
21NOAA/NWS/San Diego Weather Forecast Office, San Diego, CA
3
Schematic illustration of regional variations in the primary weather phenomena
that lead to extreme precipitation, flooding and contribute to water supply in the Western U.S.
Atmospheric
Rivers
(fall and winter)
Key
Weather
Phenomena
Great Plains Deep
Convection
(spring and summer)
Spring Front
Range Upslope
(rain/snow)
Southwest
Monsoon
(summer & fall)
When atmospheric rivers strike coastal mountains (Ralph et al. 2003)
Details (e.g., wind direction) of the atmospheric river determine which
watersheds flood
Schematic “strawman” network of new sensors to improve monitoring, prediction and climate
trend detection for hydrometeorological conditions that create extreme precipitation & flooding.
6
Existing SNOTEL sites color coded to their altitude range. Red ovals highlight regions where a subset of the
existing SNOTEL sites would have additional sensors emplaced to support better spring snow melt monitoring
and prediction, or where new sites would be needed to broaden the altitude range of coverage.
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California has begun
implementation of key
land-based elements of
this Obs’ Vision
An AR-focused long-term observing
network is being installed in CA as part
of a 5-year project between CA-DWR,
NOAA and Scripps Inst. of
Oceanography
- Installed 2008-2012
- 93 field sites
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Core Observing System Concepts
• The lower 5,000 feet of the atmosphere is where much of
the “action” takes place, but is poorly observed
• Mountains complicate use of radars in the West,
requiring special attention to siting, scanning and profiles
• Many important storms initially take form over the Pacific
Ocean, where satellites help, but major gaps remain
• Soil and snowpack conditions in mountains impact floods
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Sensor List
• 100 new low-mid altitude soil moisture observing
sites
• 125 existing high-altitude sites with new snowrelated data
• 100 new GPS-met observing sites
• 25 snow-level radars
• 25 wind profiling/ARO sites
• 14 C-band scanning radars
• 10 X-band scanning radars or mini CASA networks
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