CW3E partners with California Department of Water Resources, California Geological Survey, US Geological Survey, and the Western Regional Climate Center to assess post-fire debris flow hazards in northern California

CW3E partners with California Department of Water Resources, California Geological Survey, US Geological Survey, and the Western Regional Climate Center to assess post-fire debris flow hazards in northern California

December 2, 2016

Highlights

Atmospheric River knowledge and tools support post-fire debris flow hazard mitigation and fast-response studies of debris flow-meteorology linkages

An important consequence of the recent record drought in parts of California is the occurrence of major wildfires. The Butte, Valley and Soberanes fires occurred in the last 18 months and have been some of the largest in California history. These tragic burns caused many adverse impacts at the time, and continue to create natural hazards due to the increased risk of damaging debris flows that can occur after the rains return.

California’s burned steeplands are prone to hazardous debris flows during winter storms. Wildfires remove vegetation and alter soil properties, increasing the likelihood of debris flows, even for relatively low intensity storms. When rainfall of sufficient intensity and duration impacts recently burned steeplands, landslides and surface runoff can mobilize ash, rocks, and other material into debris flows that devastate life and property.

California’s Department of Water Resources (DWR) is sponsoring work to examine the role of Atmospheric Rivers on flooding and landslide occurrence and magnitude. The project is led by the Center for Western Weather and Water Extremes (CW3E) at Scripps Institution of Oceanography and includes a team of experts from Scripps, California Geological Survey (CGS) and the U.S. Geological Survey (USGS) Landslide Hazards Team.

Within these burn areas, the geology team, led by Jeremy Lancaster of CGS, is deploying sensors and making measurements in the burn areas when conditions warrant. Doing so requires making decisions on whether to make observations at a study site following a storm event. In support of this, CW3E Graduate Student researchers Nina Oakley and Meredith Fish are using new knowledge of weather systems capable of producing intense precipitation, especially Atmospheric Rivers, to evaluate the potential for high-intensity precipitation over the Soberanes Fire, Butte Fire, and Valley Fire burn areas to advise Lancaster. Key to these preparations and day-to-day decisions are the new Atmospheric River forecasting tools at CW3E. Additionally, post-storm, CW3E scientists will compile meteorological data relevant to the storm event such as maximum precipitation intensity, storm total precipitation, radar imagery, an evaluation of Atmospheric River variables, and any information unique to that storm. For events that produce a debris flow response, a more in-depth case study will be conducted combining both geologic and atmospheric information.

Figure 1: Map of three burn areas that we propose to assess: Soberanes, Valley, and Butte wildfires.

Synthesis of the information collected through these storm and debris flow response logs will provide insight to post-fire debris flow triggering rainfall thresholds across northern California and the meteorological conditions that produce such rainfall. This integrated approach of meteorologists and geologists working together to address the post-fire debris flow issue will help advance our knowledge of these potentially hazardous events. This knowledge will be incorporated into landslide/debris flow hazard outlooks that factor in both landscape conditions (e.g., fire) and meteorology (e.g., extreme precipitation from Atmospheric Rivers)

Figure 2: Debris flow deposits stopped by cement barriers outside the Big Sur Lodge in California. This event was triggered by rain falling on burned steeplands in 2009, near an area now burned again by the Soberanes wildfire. (credit: David Longstreth, CGS).


Figure 3: During Fall 2016, USGS and CGS researchers install a rain near Pfeiffer Falls in the Soberanes Fire burn area to measure the rainfall intensities that trigger post-fire debris flows.

Contacts: Jeremy Lancaster (CGS), Nina Oakley (DRI and CW3E), John Stock (USGS), F.M. Ralph (CW3E)

Congressional Briefing on “A New Frontier in Water Operations: Atmospheric Rivers, Subseasonal-to-Seasonal Predictions and Weather Forecasting Technology”

Congressional Briefing on “A New Frontier in Water Operations: Atmospheric Rivers, Subseasonal-to-Seasonal Predictions and Weather Forecasting Technology”

July 27, 2016

An interagency, cross-disciplinary team of experts recently convened in Washington to provide Congressional staff with a briefing on atmospheric rivers, subseasonal-to-seasonal precipitation prediction needs, and the benefits of enhanced predictive forecasting technology to the future of water management.

Attendees heard from a diverse panel of experts representing a broad spectrum of perspectives, including government engagement by the National Weather Service and the U.S. Army Corps of Engineers, scientific findings presented by the Scripps Institution of Oceanography, and regional impacts to stakeholders represented by the Western States Water Council.

This briefing highlighted CW3E’s major effforts on atmospheric river science, monitoring and predictions, and their application to possible new water management strategies, such as Forecast-Informed Reservoir Operations (FIRO; http://cw3e.ucsd.edu/FIRO/), which is co-led by CW3E’s Director, F. Martin Ralph. Roughly 40 people attended, including representatives of congressional offices, committees, ACWA, federal agencies and other groups.

Click here for a summary.

Contact: F. Martin Ralph (mralph@ucsd.edu)

Publication Notice: CalWater Field Studies Designed to Quantify the Roles of Atmospheric Rivers and Aerosols in Modulating U.S. West Coast Precipitation in a Changing Climate

CW3E Publication Notice

CalWater Field Studies Designed to Quantify the Roles of Atmospheric Rivers and Aerosols in Modulating U.S. West Coast Precipitation in a Changing Climate

November 28, 2016

Ralph F.M., K. A. Prather, D. Cayan, J.R. Spackman, P. DeMott, M. Dettinger, C. Fairall, R. Leung, D. Rosenfeld, S. Rutledge, D. Waliser, A. B. White, J. Cordeira, A. Martin, J. Helly, and J. Intrieri, 2016: CalWater Field Studies Designed to Quantify the Roles of Atmospheric Rivers and Aerosols in Modulating U.S. West Coast Precipitation in a Changing Climate. Bull. Amer. Meteor. Soc. 97, yyy-zzz. doi: 10.1175/BAMS-D-14-00043.1.

This paper summarizes the 8-year-long CalWater program of field studies, from planning to field operations and analysis efforts. It also summarizes the major motivations for the program as well as science gaps addressed, and serves as the standard reference for future CalWater analysis papers.

Contact: F. Martin Ralph (mralph@ucsd.edu)

Abstract

Quantifying the roles of atmospheric rivers and aerosols in modulating U.S. West Coast precipitation, water supply, flood risks and drought in a changing climate.

The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region’s economy and environment, as evidenced by the recent California drought. This variability is strongly influenced by atmospheric rivers (AR), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, and by aerosols (from local sources and transported from remote continents and oceans) that modulate clouds and precipitation. A better understanding of these processes is needed to reduce uncertainties in weather predictions and climate projections of droughts and floods, both now and under changing climate conditions.

To address these gaps a group of meteorologists, hydrologists, climate scientists, atmospheric chemists, and oceanographers have created an interdisciplinary research effort, with support from multiple agencies. From 2009-2011 a series of field campaigns (CalWater 1) collected atmospheric chemistry, cloud microphysics and meteorological measurements in California and associated modeling and diagnostic studies were carried out. Based on remaining gaps, a vision was developed to extend these studies offshore over the Eastern North Pacific and to enhance land-based measurements from 2014-2018 (CalWater 2). The data set and selected results from CalWater 1 are summarized here. The goals of CalWater-2, and measurements to date, are then described.

CalWater is producing new findings and exploring new technologies to evaluate and improve global climate models and their regional performance and to develop tools supporting water and hydropower management. These advances also have potential to enhance hazard mitigation by improving near-term weather prediction and subseasonal and seasonal outlooks.

October 2016 Summary

October 2016 Summary

November 23, 2016

CW3E provides a summary of October 2016, one of the wettest Octobers on record for the Western United States. Several Atmospheric Rivers (ARs) made landfall along the U.S. West Coast and led to record setting precipitation production. For specific details on AR events refer to the CW3E AR Summaries, found on the CW3E News page.

Click here for a pdf file of this information.



 

 

 

 

 

 

 

 

 

Summary provided by C. Hecht, B. Kawzenuk, and F.M. Ralph

Publication Notice: Forecasting Atmospheric Rivers during CalWater 2015

CW3E Publication Notice

Forecasting Atmospheric Rivers during CalWater 2015

November 22, 2016

Cordeira, J., F. Ralph, A. Martin, N. Gaggini, R. Spackman, P. Neiman, J. Rutz, and R. Pierce, 0: Forecasting Atmospheric Rivers during CalWater 2015. Bull. Amer. Meteor. Soc., 0, doi: 10.1175/BAMS-D-15-00245.1.

As part of CW3E’s mission and goals a new set of atmospheric river (AR)-focused diagnostic and prediction tools have been created, in close partnership with Plymouth State University’s Prof. Jason Cordeira, and building upon work done earlier at NOAA under the HMT Program (see Ralph et al. 2013 BAMS, Wick et al. 2013 Wea. Forecasting). These developments were accelerated and focused by the needs for specialized AR forecast displays to support the CalWater field campaigns in 2014 and 2015 (see Ralph et al. 2016, BAMS). CalWater used research aircraft to observe atmospheric rivers and carried out aerosol science. These developments are summarized in a paper on the forecasting tools that were used in the CalWater field campaign by CW3E researchers and collaborators (Cordeira et al.) that was recently published in Bulletin of the American Meteorological Society (BAMS). The paper details some of the new AR forecasting tools developed using NCEP Global Forecast System and Global Ensemble Forecast System. A novel AR landfall detection forecast tool illustrates the probability of AR conditions at different locations along the western coast of the US. Another new forecast tool that used the various ensemble members illustrates the possible range of integrated water vapor transport (IVT) at a specific location using each of the ensemble members. In addition, the high quality plots of forecasted IVT and observed integrated water vapor supported the CalWater field campaign. Beyond supporting the CalWater Field Campaign, these new forecasting tools will likely improve AR forecasting throughout the West Coast. All these and more of the new forecasting tools can be found on the CW3E website under “Atmospheric River Resources.”

84-h NCEP GFS gridded forecast of IVT magnitude (kg m-1s-1 and direction; initialized at 1200 UTC on 3 February 2015; (b) as in (a), except for the verifying analysis of IVT magnitude and direction at 0000 UTC 7 February 2015 with overlaid draft flight track of the NOAA G-IV aircraft (c) GPS-derived IWV (mm) at 0015 UTC 7 February 2015.


Abstract

Atmospheric Rivers (ARs) are long and narrow corridors of enhanced vertically integrated water vapor (IWV) and IWV transport (IVT) within the warm sector of extratropical cyclones that can produce heavy precipitation and flooding in regions of complex terrain, especially along the U.S. West Coast. Several field campaigns have investigated ARs under the “CalWater” program of field studies. The first field phase of CalWater during 2009–2011 increased the number of observations of precipitation and aerosols, among other parameters, across California and sampled ARs in the coastal and near-coastal environment, whereas the second field phase of CalWater during 2014–2015 observed the structure and intensity of ARs and aerosols in the coastal and offshore environment over the Northeast Pacific. This manuscript highlights the forecasts that were prepared for the CalWater field campaign in 2015 and the development and use of an “AR portal” that was used to inform these forecasts. The AR portal contains archived and real-time deterministic and probabilistic gridded forecast tools related to ARs that emphasize water vapor concentrations and water vapor flux distributions over the eastern North Pacific, among other parameters, in a variety of formats derived from the NCEP Global Forecast System and Global Ensemble Forecast System. The tools created for the CalWater 2015 field campaign provided valuable guidance for flight planning and field activity purposes, and may prove useful in forecasting ARs and better anticipating hydrometeorological extremes along the U.S. West Coast.

Click here for personal use PDF file

Points of contact: Jason Cordeira, F. Martin Ralph, Brian Kawzenuk

CW3E Hosts Winter Outlook Workshop with California DWR

CW3E Hosts Winter Outlook Workshop with California DWR

November 18, 2016

The California Department of Water Resources (CDWR) and CW3E led a working meeting with researchers at the Scripps Institution of Oceanography in La Jolla, November 16-18, 2016. The workshop focused on efforts to improve sub-seasonal to seasonal prediction of precipitation, which could help agencies better manage water resources.

“We’d all like to know if 2017 will be wet or dry, but determining that is scientifically difficult. We’re trying to emphasize the need for prioritizing this research in the science community,” said Jeanine Jones, Interstate Resources Manager at CDWR.

Participants from the following agencies were in attendance: CW3E/Scripps, CDWR, Sonoma County Water Agency (SCWA), National Center for Atmospheric Research (NCAR), Natonal Weather Service (NWS), Western States Federal Agency Support Team (WestFAST), National Oceanic and Atmospheric Administration (NOAA), Plymouth State University (PSU), Oregon State University (OSU), University of California, Los Angeles (UCLA), Salt River Project (SRP), Climate Assessment for the Southwest (CLIMAS), Desert Research Institute (DRI), and Metropolitan Water District of Southern California (MWD).

Images courtesy DWR Photography – Florence Low

Water Year 2016 Summary

Water Year 2016 Summary

October 15, 2016

CW3E provides a summary of the top ten precipitation events based on the Northern Sierra 8-Station index during Water Year 2016 (Oct. 1 2015 – Sep. 30 2016). The top ten events occurred over a total of 27 days, and resulted in 30.09 inches of precipiation representing 51.89% of total water year precipitaiton and 60.2% of normal water year precipitation. All events were associated with an Atmospheric River (AR), with 6 considered strong ARs (IVT >750 kg m-1) s-1. For event specific reports refer to the CW3E News Page. For up to date AR forecasts and analysis visit the CW3E AR Portal.

Click here for a pdf file of this information.


 

 

 

 

 

Summary provided by B. Kawzenuk, and F.M. Ralph

CW3E AR Update: 4-9 November 2016 Outlook

CW3E AR Update: 4-9 November 2016 Post Event Summary

November 4, 2016

Two consecutive ARs are expected to make landfall over the Northwest U.S. and Southwest British Columbia. Current forecasts show both ARs with moderate strength, although there is high uncertainty in the forecast of the second AR. Despite high values of integrated vapor transport (IVT) forecasted precipitation values of the Northwest U.S. are modest due to the southwesterly orientation of the ARs. However, this orientation is favorable for precipitation production over Vancouver Island, where 5-day precipitation forecasts are >12 inches. For up to date AR forecasts visit the CW3E AR Portal.

Click here for a pdf file of this information.


 

 

Summary provided by C. Hecht, B. Kawzenuk, and F.M. Ralph; 3 PM PT Fri 05 Nov. 2016