A Vision for Future Observations for Western U.S.

Extreme Precipitation and Flooding

Dr. Marty Ralph Center for Western Weather and Water Extremes (CW3E)

UCSD/Scripps Institution of Oceanography

24 June 2014

“Workshop on Hydroclimate Monitoring and Measurement Needs”

Western States Water Council

San Diego, California 1

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California has deployed key land-based sensors

An Atmospheric River-focused long-term observing network is being installed in CA as part of a 5-year project between CA Dept. of Water Resources (DWR), NOAA and Scripps Inst. Of Oceanography - Installed 2008-2014 - >100 field sites

¼-scale 449-MHz wind profiler with RASS

FM-CW snow-level

radar

GPS receiver for

integrated water vapor

Soil Moisture and

Temperature Probes

White et al. 2013, J.Tech.

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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Background • The WSWC passed a Resolution in 2011 that

– “supports development of an improved observing system for Western extreme precipitation events, to aid in monitoring, prediction, and climate trend analysis associated with extreme weather events”

• NOAA’s Hydrometeorology Testbed (HMT) and other

efforts have improved understanding of how extreme events occur, have identified gaps and prototyped solutions, which are the foundation of this Vision

• The “Western Obs’ Vision” was recently published in the

Journal of Contemporary Water Research and Education (April 2014).

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Key reports, papers and other sources used to inform the development of this Vision

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Source Description and references

NRC reports Flooding in Complex Terrain; Network of Networks; GPM Satellite system

Needs assessments Workshop on non-stationarity…(2010), USBR Science and Technology Program (2011),

NOAA’s Water Cycle Science Challenge Workshop (2012), USWRP Workshop (2005)

IWRSS USACE, USGS, NOAA formal agreement and coordination; National Water Center

NOAA/HMT 10-year effort on extreme precipitation causes and predictions (Ralph et al. 2005; 2013a)

Atmospheric rivers Understanding of the joint roles of atmospheric rivers in extreme events and water

supplies in the west (Dettinger et al. 2011)

ARkStorm USGS-led emergency preparedness exercise in California focused on atmospheric rivers

NOAA/RISA Regional Integrated Science and Assessment (RISA) studies on climate change

State Climatologists Regional expertise and deep experience in states’ needs for climate information

Unmanned Aircraft NOAA UAS Program observing system gap analysis for atmospheric rivers over Pacific

NOAA Radars Cross-NOAA Radar planning team reports

NOAA Science Plans NOAA held interagency workshops on water cycle and climate science that produced

detailed recommendations for future science directions nationally (NOAA 2012a, 2012b)

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.

Ralph et al. 2014 (JCWRE)

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. (Ralph et al. 2014)

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Atmospheric Rivers

(fall and winter)

Southwest Monsoon

(summer & fall)

Great Plains Deep Convection

(spring and summer)

Front Range Upslope

(rain/snow)

Key Weather Phenomena

Figure from an article in

Scientific American by Dettinger and

Ingram (January 2013)

A Major Result from 10-years of Research

Atmospheric rivers – what they are, how they work, and their

crucial role in both water supply and flooding across much of the

U.S. West Coast

Atmospheric rivers: Two recent examples that produced extreme rainfall and flooding

From Ralph et al. 2011, Mon. Wea. Rev.

These color images represent satellite observations of atmospheric water vapor over the oceans. Warm colors = moist air Cool colors = dry air ARs can be detected with these data due to their distinctive spatial pattern. In the top panel, the AR hit central California and produced 18 inches of rain in 24 hours. In the bottom panel, the AR hit the Pacific Northwest and stalled, creating over 25 inches of rain in 3 days. 10

Overview of Scientific Findings from a Decade of Research $50 M invested over 10 years (Federal, State, Local)

Table 1. Overview of findings from 10 years of atmospheric river research

ARs can… Quantitative results Formal reference

Cause heavy rain 90% of California’s heaviest 1-3 day rain events are from ARs Ralph et al. 2010

Fill reservoirs 40-50% of northern California rain and snow Dettinger et al. 2011

Bust droughts 40% of droughts in northern California ended with an AR Dettinger 2013

Help fish 77% of Yolo Bypass inundations of fisheries/eco. significance Florsheim & Dett.2013

Cause floods 100% for key coastal watersheds (and many in Central Valley) Ralph et al. 2006

Break levees 81% of Central Valley levee breaks were AR related Florsheim & Dett.2013

Catastrophes “ARkStorm” flood scenario found >$500 Billion impact in CA Porter et al. 2011

Can be monitored Simple & complex tools can help, e.g., radar, aircraft, satellite White et al. 2013

Partly predictable Can be seen >5 days ahead; landfall position error is large Wick et al. 2013

Partly predictable Of 16 AR storms that caused 5 in of rain, 2 were predicted Ralph et al. 2010

1895-2010

Dettinger, Michael D., 2013: Atmospheric Rivers as Drought Busters on the U.S. West Coast. J. Hydrometeor, 14, 1721–1732.

Droughts, on average, end with a bang (and begin with a whimper) all over the U.S.

• Atmospheric rivers provide the bang in a large fraction of the west coast drought breaks, especially in winters

Methodology for AR duration data analysis: 13 Nov. 2004 – 8 Aug 2010

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. 20

02

)

BBY 915 MHz wind profiler: 27 Dec 2005

Russian River flooding: Feb. 2004 photo courtesy of David Kingsmill

915 MHz wind profiler GPS receiver ARO

Alt

itu

de

MSL

(km

)

0

1

2

3

GPS satellite

GPS-met receiver

Wind profiler (915 or 449 MHz)

10-m surface meteorology

tower

Wind profiler beam with 100-m vertical resolution

Atmospheric River

“Controlling layer” (upslope winds)

Surface friction and barrier jet

S-PROF precipitation

profiler; surface met; disdrometer

Snow level

Orographic cloud and precipitation

Atmospheric River Observatory

0-50 km between wind profiler/GPS-met site and S-PROF precipitation profiler

Ocean

Rain shadow

Plan view Rain

shadow

Wind direction

in AR Mountains

S-PROF data up to 10 km MSL

ARO

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Defining an AR event using three thresholds: (1) The IWV has to meet or exceed

2 cm (as in Ralph et al. 2004 and subsequent studies).

(2) The upslope IWV flux (Neiman et al. 2009) has to meet or exceed 15 cm m s-1.

(3) Both variables had to simultaneously meet or exceed those thresholds for at least 8 consecutive hours.

Example: Case 26 From: 12/26/05 08z To: 12/30/05 08z

The ending time occurs when either IWV or upslope flux falls below its respective threshold. Each case was then uniquely defined by a 96 h time interval with the 24th hour representing the start of the period for which IWV ≥ 2 cm and IWV flux ≥ 15 cm m s-1 for at least 8 h.

96 hours

At least 8 hours

ATMOSPHERIC FORCING

Storm-total upslope water vapor flux at BBY (cm m/s)

Sto

rm-t

ota

l rai

nfa

ll at

CZD

(m

m)

91 AR events observed

over 6 years

From Ralph et al. 2013, J. Hydrometeorology

Storm-total upslope water vapor flux at BBY (cm m/s)

Storm-total upslope water vapor flux at BBY (cm m/s)

Sto

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ff o

n A

ust

in C

k (m

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of

m3)

Sto

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ll at

CZD

(m

m)

91 AR events observed

over 6 years

Neiman, Hughes, Moore, Ralph, and Sukovich (MWR 2013)

The Sierra Barrier Jet is

key to regional

precipitation

Seasonality of Annual Peak Streamflow

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Seasonality of annual peak daily stream flows highlighting the preponderance of AR-dominated regions (blue dots) and Spring-melt dominated regions (red dots in mountains)

Spring-Summer snowmelt

Atmospheric rivers Fall-Winter

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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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Schematic “strawman” network of new sensors to improve monitoring, prediction and climate trend detection for hydrometeorological conditions that create extreme precipitation & flooding.

Validation of AR Forecasts - Approach

• AR features in model fields compared with satellite observations from SSMIS

• 5 models tested: NCEP, ECMWF, UKMO, JMA, & CMC

• Evaluated at lead times to 10 days

• 3 cool seasons in NE Pacific from 2008-9 to 2010-11

• Compared frequency of occurrence, width, IWV content, and landfall location

Automated Atmospheric River Detection Tool (ARDT) applied to evaluate ability of operational NWP models to predict AR events

NCEP

Satellite Observations January 7, 2009

UKMO

1-Day Fcst 7-Day Fcst

Evaluation of Atmospheric River Forecasts in Operational Ensemble Forecast Systems

G. A. Wick, P. J. Neiman, F. M. Ralph, & T. M. Hamill

NOAA ESRL/PSD, 2013

AR Landfall Position Forecast Errors While overall occurrence well forecast out to 10 days, landfall is less well predicted

and the location is subject to significant errors, especially at longer lead times

• Errors in location increase to over 800 km at 10-day lead

• Errors in 3-5 day forecasts comparable with current hurricane track errors

• Model resolution a key factor

• Models provide useful heads-up for AR impact and IWV content, but location highly uncertain

• Location uncertainty highlights limitations in ability to predict extreme precipitation and flooding

• Improvements in predictions clearly desirable

RMS Error in Forecast AR Landfall Location

From Wick et al., 2013 (Weather and Forecasting)

500 km forecast error at 5-day lead

time

Doyle, James D., Clark Amerault, Carolyn A. Reynolds, P. Alex Reinecke, 2014: Initial Condition Sensitivity and Predictability of a Severe Extratropical Cyclone Using a Moist Adjoint. Mon. Wea. Rev., 142, 320–342

Uncertainty in predicted extreme surface winds found to be associated with an AR

“The sensitivity maxima are found in the low- and midlevels, oriented in a sloped region along the warm front, and maximized within the warm conveyor belt. The moisture sensitivity indicates that only a relatively small filament of moisture within an atmospheric river present at the initial time was critically important for the development of Xynthia.”

Adjoint sensitivity valid at the initial time of 1200 UTC 26 Feb 2010 at 700 mb for water vapor (color coded). Hatched area is water vapor mixing ration >4 g kg-1.

CalWater-2* “Early Start” field campaign 3-25 February 2014

Summary Courtesy of Marty Ralph UCSD/Scripps/Center for Western Weather and Water Extremes

Up to > 12 inches of rain – some drought relief

This AR increased precipitation-to-date from 16% to 40% of normal in < 4 days in key Northern California watersheds, but runoff was muted due to dry soils.

*CalWater-2 is a 5-year program (from 2015-2019) proposed to focus on West Coast precipitation processes and how a changing climate will affect them. It is led by UCSD/Scripps with partners from DWR, CEC, NOAA, NASA, DOE and others.

SSM/I satellite observations of water vapor on 8 Feb 2014 (Courtesy G. Wick, NOAA)

Russian River’s highest flow in > 1 year

Flight area for NOAA’s G-IV aircraft on 8 Feb 2014 Goal: developing AR flight method to sample a

“frontal wave” that can cause an AR to stall over one area at landfall (G-IV PI: Chris Fairall –

NOAA; Mission Scientists: Marty Ralph – Scripps, Ryan Spackman – STC)

Hawaii

The NOAA Unmanned Aircraft Systems (UAS) Program:

Status and Activities

Gary Wick

Robbie Hood, Program Director

NASA Global Hawk during Test flight for NOAA-led Winter Storm and Pacific Atmospheric River

“WISPAR” dropsonde demonstration project

January 2011

*Courtesy Dr. Gary Wick (WISPAR Mission Scientist) 26

Benefits

Flood damages

• Western US averages $1.5 B/year

• Mitigation of 2% of this damage (or $30 M/yr) is likely

• This does not account for potential water supply benefits

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Cost Comparisons

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Scanning NEXRAD Radar on WA coast $13 M (operating Sept 2011)

California AR Network >90 sites, 4 sensor types $10 M (underway)

Operate, Maintain and Optimize - $35 M/year

Offshore Buoy and Aircraft Network $40 M to develop, acquire and deploy - 5 buoy-mounted AROs - 1-2 reconnaissance aircraft

Complete Western Network $65 M to develop, acquire and deploy - 325 new surface obs - 25 Atmospheric river observatories - 25 precipitation profiling radars - 24 new C- or X-band scanning radars

Co

mb

ine

d: $

21

0 M

ove

r 6 ye

ars

Next Step: Implementation Planning

Some alternative funding approaches

• Master Plan with Integrated Federal Appropriation(s)

• Federal, State, Local (each agency supports what it can)

• Private sector (users buy data)

Some alternative execution strategies

• Use and better support existing expertise

• Develop Regional Centers coordinated across agencies

• A single center coordinates and fills remaining gaps

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Thank You • CW3E web page

http://cw3e.ucsd.edu

Ralph, F. M., M. Dettinger, A. White, D. Reynolds, D. Cayan, T. Schneider, R. Cifelli, K. Redmond, M. Anderson, F. Gherke, J. Jones, K. Mahoney, L. Johnson, S. Gutman, V. Chandrasekar, J. Lundquist, N.P. Molotch, L. Brekke, R. Pulwarty, J. Horel, L. Schick, A. Edman, P. Mote, J. Abatzoglou, R. Pierce and G. Wick, 2014: A vision for future observations for Western U.S. extreme precipitation and flooding– Special Issue of J. Contemporary Water Resources Research and Education, Universities Council for Water Resources, Issue 153, pp. 16-32.

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Backup slides

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• Flood Preparedness

and Response

• Flood Planning

• Reservoir Coordinated

Operations

• Water Supply

Forecasting

• Monitoring

Climate Change

DWR Program

Applications of

Atmospheric Rivers

Network Data

Courtesy of Mike Anderson

- CA Dept. Water Resources

- CA State climatologist

Conceptual Observation Network and Forecast Lead Time of AR Development/Impacts

(courtesy of Dave Reynolds)

Recurving West Pacific Tropicals 5-7 days

Amplifying Jet Stream

G-IV

Profilers MJO 7-10 days

Ensemble MJO Fcst

Frontal wave stalls AR over CA - AROs

Tropical Tap?

UAVs

Landfall

Offshore Monitoring- Gap Filling Radar Demonstration in HMT

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NEXRAD precipitation estimation errors and error sources quantified

Matrosov, S.Y., F.M. Ralph, P.J. Neiman, A.B. White, 2014: Quantitative assessment of operational weather radar

rainfall estimates over California’s Northern Sonoma County using HMT-West data. J. Hydrometeor, 15, 393–

410.

Sensor List

• 100 new low-mid altitude soil moisture observing sites

• 125 existing high-altitude sites with new snow-related 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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Monitoring Atmospheric Conditions That Fuel Extreme Precipitation & Flood

New Snow and Streamflow Monitoring for Better Snow Melt Forecasts

Atmospheric River Observatories to Fill Largest Single Monitoring Gap

Offshore Monitoring to Extend Forecast Lead Times for Extreme Precipitation

Mission

Provide 21st Century water cycle science, technology and outreach to support effective policies and

practices that address the impacts of extreme weather and water events on the environment, people and

the economy of Western North America

Goal

Revolutionize the physical understanding, observations, weather predictions and climate projections of

extreme events in Western North America, including atmospheric rivers and the North American summer

monsoon as well as their impacts on floods, droughts, hydropower, ecosystems and the economy

Atmospheric

Rivers

(fall and winter)

Southwest

Monsoon

(summer & fall)

Great Plains Deep

Convection

(spring and summer)

Spring Front Range

Upslope

(rain/snow)

Center for Western Weather and Water Extremes Where: UCSD/Scripps Inst. Oceanography La Jolla, California When: Start - 2013 Who: Dr. F. M. Ralph (Director) Dr. Dan Cayan Dr. Mike Dettinger Dr. Ryan Spackman

Scripps Institution of Oceanography

CalWater 2 - Science White Paper

HMT-West innovations were key elements in NOAA’s rapid response to a flood risk crisis

• USACE was considering taking over operation of a dam in Washington State during a recent storm.

• Using the HMT ARO at the coast and NWS forecasts, USACE saw the back edge of the AR was coming ashore and thus heavy rain was about to end, so they did not take over operation from the local water agency.

• See recent journal article by White et al. (February 2012; Bulletin of the American Meteorological Society). Dept. of Commerce

Bronze Medal 2012

Courtesy of Larry Schick, US Army Corps of Engineers - Seattle

“During this current AR rain event, I have found the Westport ARO (for Wynoochee dam) and Spanaway ARO (for HH dam) very useful in short range forecast information which I needed to consult our water management people.

The question was whether to take over the dam and operate for flood control today. We were right on the threshold of taking over Wynoochee today for flood control, but had high confidence we didn't need to with the ARO info that the rain would taper off quickly -- and it did.

The Spanaway ARO is currently catching the brief heavy ran increase for HHD, but we remain confident it will move on as per forecast. Clearly the ARO info with radar, sat pix and precip trends gave us good confidence today. “

Reservoir Operation Decision - example

Background image: Integrated Water Vapor from the Global Forecast System, 30 hour forecast, Valid 0600 UTC 12 Feb

2 dropsonde transects by the Global Hawk drone across tropical tap region of an AR -37 sondes -16 h flight versus 24 h goal

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profiler

• Coastal and marine weather prediction suffers from a relative sparseness of coastal and offshore observations.

• USWRP Report No. 2 noted that “the most serious gap in the current observing system for 1-5 day forecasts is the absence of wind profiles, especially over the northeast Pacific Ocean.”

Buoy-mounted wind profilers

Examples of - Surface Observing Systems

Precipitation gauges

Surface

meteorology

& snow depth Stream level Soil moisture

Precipitation disdrometers

Real-time data access

Rain

Snow

Surface-Met

Soil and Stream

Remote Sensing Observing Systems

915-MHz wind profiler with RASS ¼-scale 449-MHz wind profiler with RASS

S-band precipitation

profiling radar (S-PROF)

FM-CW snow-level radar

X-band polarimetric, scanning

Doppler radar (HYDRO-X)

C-band scanning Doppler

radar (SKYWATER)

GPS receiver for

integrated water vapor

Profiling

Scanning

Precipitation

Boundary Layer

Scanning C-band radars (2 new)

Scanning X-band radar (1 new)

Atmos. River Observatory (1 new plus 1 from DWR)

Precipitation profiling radars (7 new plus 1 from NOAA)

Atmospheric Rivers, Floods and the Water Resources of California by Mike Dettinger, Marty Ralph, , Tapash Das, Paul Neiman, Dan Cayan

Water, 2011 (in Press)

25-35% of annual precipitation in the

Pacific Northwest fell in association with

atmospheric river events

35-45% of annual precipitation in California

fell in association with atmospheric river events

An average AR transports the

equivalent of 7.5 times the average discharge of the

Mississippi River, or ~10 M acre feet/day

4 Jan 2008, 1500 UTC

5 Jan 2008, 0300 UTC

4 Jan 2008, 2100 UTC

Time of max AR bulk flux at BBY: 1500 UTC 4 Jan

Time of max AR bulk flux at GLA: 0300 UTC 5 Jan

Time of max AR bulk flux at PPB: 2100 UTC 4 Jan

AR Propagation: ~12 m s-1.

½-day lead time for SoCal