Lake Mendocino Forecast-Informed Reservoir Operations (FIRO) Workshop Summary

Lake Mendocino Forecast-Informed Reservoir Operations (FIRO) Workshop Summary

July 5, 2016

Experts from multiple disciplines and organizations came together for the third annual FIRO workshop, which was held at UC San Diego/Scripps Institution of Oceanography (SIO) from 27-29 June 2016. This workshop was hosted jointly by the Sonoma County Water Agency (SCWA) and SIO’s Center for Western Weather and Water Extremes (CW3E). It was organized by the FIRO Steering Committee, co-chaired by CW3E’s Marty Ralph and SCWA’s Jay Jasperse. There were a total of 52 attendees from organizations including the US Army Corps of Engineers (USACE), California Department of Water Resources (CA DWR), National Oceanic and Atmospheric Administration (NOAA), US Geological Survey (USGS), US Bureau of Reclamation (USBR), SCWA and CW3E.

During the workshop, participants shared recent updates on FIRO activities, discussed reservoir conditions during water year 2016, summarized progress toward goals identified in the FIRO Workplan and identified issues to address regarding development of the Lake Mendocino FIRO “Preliminary Viability Assessment.” Progress was summarized on defining FIRO information requirements (e.g., forecast parameters and lead times), assessing current forecast skill, exploring the origins of forecast errors, advances in atmospheric river science, results of preliminary estimates of FIRO implications on Lake Mendocino water supply, and discussion of potential additional reservoirs for which FIRO may hold promise. Individual task groups (Preliminary Viability Assessment, Science, and Communications/Outreach) conducted break-out sessions in order to discuss progress and next steps towards meeting project goals (see photos below). In addition, the 11-member Lake Mendocino FIRO Steering Committee met afterward to review the workshop outcomes and plans. In short, the initial goals of year-1 of the 5-year FIRO Workplan are on track to be met, including development of the Preliminary Viability Assessment. Longer-term actions supporting the Full Viability Assessment are beginning and transferability is being discussed.

Lake Mendocino FIRO is summarized at http://cw3e.ucsd.edu/firo/.

Contacts: F. Martin Ralph (CW3E Director; mralph@ucsd.edu) and J. Jasperse (SCWA Chief Engineer; Jay.Jasperse@scwa.ca.gov)

Mesoscale Frontal Wave AR during CalWater-2014

CW3E Publication Notice

An Airborne and Ground-Based Study of a Long-Lived and Intense Atmospheric River with Mesoscale Frontal Waves Impacting California during CalWater-2014

May 10, 2016

Neiman, P.J., B.J. Moore, A.B. White, G.A. Wick, J. Aikins, D.L. Jackson, J.R Spackman, and F.M. Ralph, 2016: An Airborne and Ground-Based Study of a Long-Lived and Intense Atmospheric River with Mesoscale Frontal Waves Impacting California during CalWater-2014. Mon. Wea. Rev., 144, 1115-1144.

This study provides the most comprehensive observations to date of a mesoscale frontal wave associated with an atmospheric river, including its structure offshore, landfall characteristics and impacts on precipitation. It utilizes research aircraft, a unique array of coastal hydrometeorological measurements and inland data. This paper reflects the broader scientific collaboration between CW3E and NOAA/PSD, and adds to the knowledge of phenomena that are critical to creating extreme precipitation on the U.S. West Coast – a major thrust of CW3E. Dr. Ralph contributed to this paper by proposing the experiment (Ralph et al. 2016 BAMS), identifying the science objective for the flights (i.e., mapping out the structure of a mesoscale frontal wave with dropsondes and airborne radar), laying out the flight tracks, guiding the mission onboard, having been the PI of the major projects that created the unique land-based observing network (NOAA HMT- Ralph et al. 2013 BAMS, and the DWR-sponsored EFREP mesonet – White et al. 2013 JTech) used in the study and contributing to the analysis and interpretation of the measurements in this paper.

Contacts: Paul Neiman (paul.j.neiman@noaa.gov) and F. Martin Ralph (mralph@ucsd.edu)

Abstract

The wettest period during the CalWater-2014 winter field campaign occurred with a long-lived, intense atmospheric river (AR) that impacted California on 7–10 February. The AR was maintained in conjunction with the development and propagation of three successive mesoscale frontal waves. Based on Lagrangian trajectory analysis, moist air of tropical origin was tapped by the AR and was subsequently transported into California. Widespread heavy precipitation (200–400 mm) fell across the coastal mountain ranges northwest of San Francisco and across the northern Sierra Nevada, although only modest flooding ensued due to anomalously dry antecedent conditions. A NOAA G-IV aircraft flew through two of the frontal waves in the AR environment offshore during a ;24-h period. Parallel dropsonde curtains documented key three dimensional thermodynamic and kinematic characteristics across the AR and the frontal waves prior to landfall. The AR characteristics varied, depending on the location of the cross section through the frontal waves. A newly implemented tail-mounted Doppler radar on the G-IV simultaneously captured coherent precipitation features. Along the coast, a 449-MHz wind profiler and collocated global positioning system (GPS) receiver documented prolonged AR conditions linked to the propagation of the three frontal waves and highlighted the orographic character of the coastal-mountain rainfall with the waves’ landfall. Avertically pointing S-PROF radar in the coastal mountains provided detailed information on the bulk microphysical characteristics of the rainfall. Farther inland, a pair of 915-MHz wind profilers and GPS receivers quantified the orographic precipitation forcing as the AR ascended the Sierra Nevada, and as the terrain-induced Sierra barrier jet ascended the northern terminus of California’s Central Valley.

CW3E represented in recent policy and program meetings

CW3E Represented in Recent Policy and Program Meetings

June 8, 2017

During the last few weeks CW3E’s perspectives have been highlighted at three science policy-oriented meetings. The connection between CW3E’s scientific activities, practical applications and water policy implications is a common theme among them. The meetings and a brief synopsis are provided below:

1) AGU Congressional briefing on role of basic Geoscience in American Security May 2016

AGU invited three speakers to a Congressional briefing they organized to communicate to staff supporting a number of elected officials and policy committees. The goal was to make the connection between basic science advances (and the funding that has supported them), and benefits to American Security. CW3E’s Director, Dr. Ralph, represented the role of basic geoscience research in advancing water security in the Western U.S. His presentation emphasized the critical roles of key science funding strategies, from standard grants programs, to directed research efforts, cooperative agreements and federal labs. And in the end concluded that many breakthrough advances result not from a systems engineering approach to deciding what to do, but from ideas that are “outside the box.” He also highlighted that science, at its core, is fundamentally a creative endeavor that requires long-term support for people in their careers and for the organizations that host them. AGU has posted a video of the briefings here.

2) NOAA Water Information “Listening Session” in Sacramento May 2016

NOAA invited water management stakeholders from across the West to hear about the National Water Center they are creating in Alabama and to listen to stakeholders interests and needs for weather and water information to support water supply, flood mitigation and endangered species restoration in the West. CW3E was represented by Dr. Ralph, who brought Scripps science into the discussion, and supported major points presented by water managers concerning the vital role of atmospheric rivers in western water decisions. NOAA held one other regional “listening session” – in Alabama, and is holding one more “National” session in July. They will be considering input from these meeting as they develop their agency’s strategies in the coming years to support water information needs for the nation.

3) WSWC S2S Workshop San Diego June 2016

The National Academies of Science recently released a report on the subject of science needed to enable subseasonal-to-seasonal predictions to support decisions. The Western States Water Council (a group supporting the Governors of 17 Western States) organized a regional Workshop in San Diego in early June to discuss both the user requirements for better forecasts and the science opportunities to achieve them. CW3E was represented well, including participation by Sasha Gerhunov, Tamara Shulgina and Marty Ralph, including a presentation by Marty on observing system needs to support the goals.

CW3E AR Update:Post-Event Summary: 7-10 April 2016

CW3E AR Update: 7-10 April 2016 Post Event Summary

April 13, 2016

CW3E and WRCC give a post-event storm summary about two cutoff lows that made landfall over Southern California during 7-10 April 2016. Precipitation was widespread throughout the Southeastern United States with 72-hr accumulations generally ~0.5-3 inches. While the low pressure system entrained moisture from the tropics, spatial characteristics of IWV >20 mm and IVT >250 kg m-1 s-1 did not meet the necesarry requirements to be considered an Atmospheric River.

Click here for a pdf file of this information.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Odds of Reaching 100% Water Year Precipitation – April Update

Odds of Reaching 100% of Normal Precipitation for Water Year 2016 in California (April update)

April 10, 2016

Contribution from Dr. M.D. Dettinger, USGS

March is over (and the precipitation totals are in), so here is the update to the historical odds of getting to normal (and other fractions of normal) precipitation this year. Notice that the odds from the March 1 situation (in parens; click here for March report) are included alongside the April 1 odds, so that you can see whether March wetness made much difference. In fact, the odds haven’t changed too much in most areas because, although March was wettish (except down south), those additions were balanced in these April odds by the fact that we have almost run out of time this year to get much more precipitation.

Bottom lines (both of which you probably already know): We’re not going to fill the precipitation deficits we accumulated over the past 5 years with this year’s precipitation (except, long-odds, maybe in eastern NV). In southern California, the precipitation situation is especially grim and even the odds of making it to 75% of normal this year are well less than even.


 

How these probabilities were estimated:

At the end of a given month, if we know how much precipitation has fallen to date (in the water year), the amount of precipitation that will be required to close out the water year (on Sept 30) with a water-year total equal to the long-term normal is just that normal amount minus the amount received to date. Thus the odds of reaching normal by the end of the water year are just the odds of precipitation during the remaining of the year equaling or exceeding that remaining amount.

To arrive at the probabilities shown, the precipitation totals for the remaining months of the water year were tabulated (for all years, for only El Ninos, or for only La Ninas) and the number of years in which that precipitation total equaled or exceeded the amount still needed to reach normal were counted. The fraction of years that at least reached that threshold is the probability estimate. This simple calculation was performed for a full range of possible starting months (from November thru September) and for a wide range of initial (year-to-date) precipitation conditions. The calculation was also made for the probabilities of reaching 75% of normal by end of water year, 125%, and 150%, to ensure that the resulting tables of probabilities cover almost the full range of situations that will come up in the future. Contact mddettin@usgs.gov for more information.

[One key simplifying assumption goes into estimating the probabilities this way: The assumption that the amount of precipitation that will fall in the remainder of a water year does not depend on the amount that has already fallen in that water year to date. This assumption was tested for each month of the year by correlating historical year-to-date amounts with the remainder-of-the-year amounts, and the resulting correlations were never statistically significantly different from zero, except possibly when the beginning month is March, for which there is a small positive correlation between Oct-Mar and Apr-Sept precipitation historically.]

Contact: Michael Dettinger (USGS)

Odds of Reaching 100% Water Year Precipitation – March Update

Odds of Reaching 100% of Normal Precipitation for Water Year 2016 in California (March update)

March 10, 2016

Contribution from Dr. M.D. Dettinger, USGS

The Febraury 2016 precipitation observations are now in, and have allowed for an update to the calculation of the odds of reaching 100% of normal for the water year across three key climate divisions of California and Nevada. These odds have decreased slightly across all of California and Nevada as a result of a very dry February. The odds of reaching 100% of normal Water Year precipitation in the key northern California climate division that encompasses the Sacramento River, and the State’s largest water supply reservoirs, decreased from 52% as of the end of January 2016, to 38% as of the end of February 2016. A series of Atmospheric Rivers have made landfall over Northern California and produced heavy precipitation throughout early March and will most likely cause changes in these odds when updated at the end of March.


How these probabilities were estimated:

At the end of a given month, if we know how much precipitation has fallen to date (in the water year), the amount of precipitation that will be required to close out the water year (on Sept 30) with a water-year total equal to the long-term normal is just that normal amount minus the amount received to date. Thus the odds of reaching normal by the end of the water year are just the odds of precipitation during the remaining of the year equaling or exceeding that remaining amount.

To arrive at the probabilities shown, the precipitation totals for the remaining months of the water year were tabulated (for all years, for only El Ninos, or for only La Ninas) and the number of years in which that precipitation total equaled or exceeded the amount still needed to reach normal were counted. The fraction of years that at least reached that threshold is the probability estimate. This simple calculation was performed for a full range of possible starting months (from November thru September) and for a wide range of initial (year-to-date) precipitation conditions. The calculation was also made for the probabilities of reaching 75% of normal by end of water year, 125%, and 150%, to ensure that the resulting tables of probabilities cover almost the full range of situations that will come up in the future. Contact mddettin@usgs.gov for more information.

[One key simplifying assumption goes into estimating the probabilities this way: The assumption that the amount of precipitation that will fall in the remainder of a water year does not depend on the amount that has already fallen in that water year to date. This assumption was tested for each month of the year by correlating historical year-to-date amounts with the remainder-of-the-year amounts, and the resulting correlations were never statistically significantly different from zero, except possibly when the beginning month is March, for which there is a small positive correlation between Oct-Mar and Apr-Sept precipitation historically.]

Contact: Michael Dettinger (USGS)

Odds of Reaching 100% Water Year Precipitation – February Update

Odds of Reaching 100% of Normal Precipitation for Water Year 2016 in California (February update)

February 8, 2016

Contribution from Dr. M.D. Dettinger, USGS

The January 2016 precipitation observations are now in, and have allowed calculation of the odds of reaching 100% of normal for the water year across three key climate divisions of California. These odds have increased slightly in Northern California, and decreased slightly in Southern California. The previous estimate had been based on observations only through December 2015. The state was affected by a series of storms in January, including atmospheric river events, such as the one highlighted in an earlier CW3E storm summary (see the storm summaries posted on 5, 8 and 15 January 2016 under “What’s New” on the CW3E web page – cw3e.ucsd.edu). The odds of reaching 100% of normal Water Year precipitation in the key northern California climate division that encompasses the Sacramento River, and the State’s largest water supply reservoirs, increased from 32% as of the end of December 2015, to 52% as of the end of January 2016.


AR storms impact northern California: January 12-15

AR storms impact northern California: January 12-15

January 15, 2016

DRI/CW3E researcher Nina Oakley, CW3E researcher Scott Sellars and other CW3E team members evaluate two storms that had an impact on northern California as well as the Pacific Northwest from 12-15 January 2016. Fresh Sierra snow can be seen in the cover satellite image from Friday, January 15 (courtesy NWS Sacramento). The approaching clouds from the next series of storms can be seen approaching the coast as well as valley fog in the Sacramento region. The first storm event leading to this fresh snow was a moderate atmospheric river (AR) storm with 1 to over 4 inches of precipitation from northern California to the Canadian border. The second storm event was weaker and ahead of a larger scale AR that will impact the same region from 15-18 January 2016. The weaker event spun off the Aleutian Low and produced some areas of heavy snowfall in the Sierra Nevada. An outlook for the upcoming AR event for 15-18 January is also briefly examined.

Click here for a pdf file of this information.

 

 

 

 

 

 

 

Above is a sequence of SSMI water vapor imagery from 10-13 January 2016 which shows the AR propagating towards northern California and making landfall.


 

 

 

 

 

 

Above is a sequence of SSMI water vapor imagery from 12-15 January 2016 which shows the first AR making landfall and the dissipation of the second AR as it approaches land.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

California Storm of 5 January 2016: A Preliminary Synopsis of a Marginal Landfalling Atmospheric River

California Storm of 5 January 2016: A Preliminary Synopsis of a Marginal Landfalling Atmospheric River

January 5, 2016

CW3E researchers Brian Kawzenuk and Scott Sellars and DRI researcher Nina Oakley provide a preliminary analysis and synopsis of a weak Atmospheric River that made landfall over southern California on 5 January 2016. The AR was the first event in what will be an active week over the North Pacific and brought significant precipitation throughout central and southern California. The AR initially developed near Japan and propagated across the entire North Pacific Ocean before making landfall. A brief forecast for the rest of the week is also provided by the San Diego National Weather Service Forecast Office, courtesy Roger Pierce.

Click here for a pdf file of this information.

 

 

 

 

 

 

Above is a sequence of SSMI water vapor imagery from 01-05 January 2016 which shows the Atmospheric River propagating towards California and making landfall.

-Atmospheric River intially developed over the northwestern Pacific Ocean
-AR propagated eastward and strengthened
-AR became disconnected with its parent low and began to dissipate prior to landfall
-Secondary cyclogenesis occurred just off the California/Oregon coast north of the AR shortly before landfall
-AR made landfall over southern California at ~0600 UTC 5 January 2016

 

Above is a sequence of integrated vapor transport (IVT) from the GFS analysis during 31 December 2015 to 5 January 2016 which shows the Atmospheric River propagating towards California and making landfall.


 

 

 

Above is a sequence of Jason Cordeira’s AR Landfall tool initialized between 0600 UTC 29 Dec 2015 and 0600 UTC 5 Jan 2016. The sequence shows how the forecast developed over the previous eight days and shows the skill this tool had in forecasting the AR. For more information on this product visit the AR Forecast page.

– Greater than 50% of ensemble members predicted the landfall of the AR ~8 days in advance
– Greater than 85% of ensemble members predicted the landfall of the AR ~3 days in advance
– AR conditions were not forecasted over southern CA until ~5 days in – advance
– Between days 8 and 3 duration of AR conditions forecasted ranged from ~18–48 hours
– Duration and location of AR conditions remained constant and accurate during days 0–3 forecasts

The following forecast is from the San Diego National Weather Service Forecast Office

The weather pattern in SoCal will be very active this week with several storm systems moving through the region. This afternoon through Wednesday morning will bring moderate to heavy rainfall over the coast, valleys, foothills and deserts, with heavy snowfall occurring in the mountains above 5,500 ft. Total snowfall for the through Wednesday morning will be around a foot for elevations above 5,500 ft, with lesser amounts between 4,500 and 5,500 ft. Rainfall totals through Wednesday morning will be 1 to 1.5 inches west of the mountains with local amounts near 2 inches in the foothills. If you have travel plans at anytime during the week, especially in the mountains, check local conditions and be prepared for inclement weather. Another storm with moderate to high impacts will affect the region Wednesday afternoon through Wednesday night. A third system on Thursday will bring additional rain and mountains snow, but it appears to be less intense than the first two.

A Preliminary Summary of Highway 58 and I-5 Flooding Event of October 15, 2015

A Preliminary Summary of Highway 58 and I-5 Flooding Event of October 15, 2015

October 27, 2015

Nina Oakley (WRCC/DRI), Jeremy Lancaster (CGS), John Stock (USGS), Brian Kawzenuk (CW3E), and Mike Kaplan (DRI) provide an analysis and synopsis of the meteorological and geological conditions that produced alluvial fan flooding over portions of Highway 58 and Interstate 5 in southern California. A weakening cutoff low that had entrained subtropical moisture moved onshore over southern California, initiating convection and localized heavy precipitation. Hillslope runoff concentrated in steep valleys where it entrained debris. The debris then flowed onto steep alluvial fans at the base of these valleys, inundating portions of I-5 and State Hwy 58.

Click here for pdf file of this information.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Click here for pdf file of this information.