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.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Recent Rainy Week in San Diego County

Recent Rainy Week in San Diego County

January 8, 2016

El Nino-fueled storms over the last few days, including a land-falling atmospheric river on 5 January (see cw3e.ucsd.edu for more details), have brought San Diego county’s accumulated winter precipitation to well above normal for this time of year. These numbers are tracked by the California-Nevada Applications program (cnap.ucsd.edu) and the Center for Western Weather and Water Extremes (cw3e.ucsd.edu) at UCSD’s Scripps Institution of Oceanography, in association with KPBS. The precipitation tracking tool shows the impact of the recent storms on the accumulated winter precipitation:

In the last three days, San Diego county has received almost 17% of the amount of precipitation it receives in an entire year, on average.

Precipitation gauge records compiled by the California Nevada River Forecast Center show accumulations of 3-5″ over much of the Los Angeles basin in the 72 hour period, reaching 7″ in some locations in the surrounding mountains. San Diego county accumulations are 1-3″ over much of the city, and 4-5″ in the North County interior:

These storms bring San Diego county’s running total accumulated precipitation so far this winter to 42% of the total typically received over an entire average year. This is an above-average value for the first time since the winter started; typically, by this point in the winter, San Diego will have accumulated 32% of the average year-end total precipitation.

Before the recent storms hit, the accumulated precipitation in the Los Angeles region since the winter started was only 11% of the typical end-of-winter total, far below the average value of 29%. In three days the accumulation has jumped to 27%. This rapid increase is more than is experienced in 95 out of 100 wet periods of 3-day duration in the region, leading to strong flows in the normally quiescent Los Angeles river and localized flooding in Southern California coastal areas.

Precipitation during the week was widespread, with rain and snow delivered from Washington to Northern Mexico. California statewide totals also were boosted during the Jan 4-7 period (cnap.ucsd.edu), although amounts were not as heavy in Northern California as they were in Southern California.

These accumulated precipitation totals can be tracked in real time from the California-Nevada Applications Project (CNAP) and Center for Western Weather and Water Extremes (CW3E)’s “San Diego Precipitation Page”. This includes monitoring of how current winter precipitation compares to that during the last 5 strongest El Nino winters (1982-83, 1997-98, 1957-58, 1972-73, and 1965-66), shown as the colored lines in the upper panels:

The current El Nino event is is one of the three strongest in records that go back to 1950, with a broad area of unusually warm ocean surface waters in the tropical Pacific ocean and highly anomalous winds and other atmospheric conditions in the region. El Nino events can alter the North Pacific winter storm track, producing unusually wet winters in Southern California about 60% of the time, compared to about 11% of the time during years when no El Nino or its opposite, La Nina, is present. Forecasts indicate that El Nino conditions are likely to persist through the spring of 2016, before fading in the early summer of 2016.

Points of contact: David Pierce (dpierce@ucsd.edu), Dan Cayan (dcayan@ucsd.edu), and Marty Ralph (mralph@ucsd.edu) at the Scripps Institution of Oceanography, UCSD.

For a PDF version of this information click here.

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.

Pacific Northwest Storm of 13-15 November 2015: A Synopsis of Landfalling Atmospheric River Conditions

Pacific Northwest Storm of 13-15 November 2015: A Synopsis of Landfalling Atmospheric River Conditions

November 25, 2015

CW3E researcher Brian Kawzenuk provides an analysis and synopsis of an Atmospheric River that made landfall along the U.S. Pacific Northwest over the 13-15 November 2015 period. The AR made initial landfall along the Washington coast and lead to significant precipitation for nearly three days throughout western Oregon, Washington, and British Columbia. The AR initially developed near Japan and propagated across the entire North Pacific Ocean before making landfall.


 

Above is a sequence of 30-minute NEXRAD radar composite imagery from 12-15 November 2015 which shows precipitation throughout the Pacific Northwest during nearly the entire period.


 

 

The above loop shows SSMI Integrated Water Vapor during 10-15 November 2015.


 

 

 

 

 

 

Improving Understanding of Atmospheric Rivers: Legislation Authorized by California Governor Brown

Improving Understanding of Atmospheric Rivers: Legislation Authorized by California Governor Brown

October 12, 2015

The Center for Western Weather and Water Extremes (CW3E) is grateful for the approval of legislation that will improve California’s ability to respond to major precipitation episodes. This legislation, recently approved, will aim to allow the state of California to better manage water supplies by expanding climate and weather research that is focused on the causes of drought and flood.

The two images below show an example of research aimed at improving forecasting ability. The two maps show the integrated water vapor (IWV) forecast from February 9, 2014. The top panel shows a CW3E simulation by a regional model (called West-WRF). The bottom panel shows a national forecast by the Global Forecasting System (GFS). The CW3E simulation offers a resolution of 9km while the national forecast is at 0.5 degrees (approximately 100km). This improved model forecast horizontal resolution will allow forecasters to better pinpoint heavy precipitation events aimed at the west coast.

westwrf_forecast_comparison

Please find more at the Scripps Institution of Oceanography news page: https://scripps.ucsd.edu/news/legislation-improve-understanding-atmospheric-rivers-authorized-governor

Test Beds Linking Research and Forecasting

Test Beds Linking Research and Forecasting

September 10, 2013

TestBeds Linking Research and Forecasting

A new article written by Marty Ralph and colleagues was recently published in the Bulletin of the American Meteorological Society focusing on the emergence of weather-related test beds. The paper provides a brief background on how these test beds successfully bridged the gap between research and forecasting operations; summarizes test bed origins, methods and selected accomplishments; and provides a perspective on the future of test beds. A personal use copy of the paper can be obtained here.

Publication Notice: An Airborne Study of an Atmospheric River over the Subtropical Pacific during WISPAR: Dropsonde Budget-Box Diagnostics and Precipitation Impacts in Hawaii

CW3E Publication Notice

An Airborne Study of an Atmospheric River over the Subtropical Pacific during WISPAR: Dropsonde Budget-Box Diagnostics and Precipitation Impacts in Hawaii

Satellite image swath at 1921 UTC 3 Mar 2011 of IWV (cm; color scale at bottom) from the SSMIS. The unadjusted G-IV flight track is superimposed, along with dots marking the positions and times of the dropsonde releases late on 3 Mar (2007–2343 UTC) and early on 4 Mar (0003–0302 UTC) 2011. The operational rawinsonde locations at Lihue (LIH) and Hilo (ITO) on Hawaii are shown. Manually smoothed satellite-derived sea surface temperatures (8C; contours) from the Reynolds et al. (2007) daily 0.25830.258 resolution optimally interpolated infrared product are also shown. (From Neiman et al. 2014.).

The upcoming CalWater-2 experiment, which is organized by CW3E scientists and others from NOAA, NASA, DOE, USGS and elsewhere, will be using research aircraft to observe atmospheric rivers over the Northeastern Pacific Ocean and U.S. West Coast. This presents an opportunity to measure atmospheric river (AR) structure and embedded physical processes that control the water vapor transport budget. This paper develops some of the key diagnostic tools needed and demonstrates them using a flight pattern and dropsondes designed to calculate the vertical profile of water vapor flux divergence (and other key parameters) in an AR. These tools and associated flight strategies will be critical to future airborne field campaigns that will enable CW3E and colleagues to diagnose key AR-relevant physical processes and to then assess in detail their representation in weather and climate models.

In 2011 a short airborne campaign was conducted to demonstrate the ability of an unmanned aircraft (Global Hawk) to fly over ARs and sample them using dropsondes. As part of this successful demonstration of UAS technology – WISPAR – a special flight of the NOAA G-IV aircraft was also conducted. The paper presents a summary of this flight, including use of drospondes from a box pattern over an AR to calculate vertical profiles of divergence, water vapor flux divergence, sensible heat flux divergence and vertical air motions. The same AR studied here also produced over 10 inches of rain on the normally dry side of the Hawaiian Islands due to the anomalous water vapor transport conditions associated with the AR hitting the region.

Abstract

The Winter Storms and Pacific Atmospheric Rivers (WISPAR) experiment was carried out in January–March 2011 from the National Aeronautics and Space Administration (NASA) Dryden Flight Research Center as a demonstration for utilizing unmanned aerial systems in meteorological research and operations over data-sparse oceans. One of the campaign’s three missions was coordinated with a manned National Oceanic and Atmospheric Administration Gulfstream-IV (G-IV) flight out of Honolulu, Hawaii, on 3–4 March 2011. The G-IV, which flew through a developing atmospheric river (AR) west of Hawaii, represents the cornerstone observing platform for this study and provided the southernmost dropsonde observations of an AR published to date in the subtropical Northern Hemisphere. The AR exhibited characteristics comparable to those observed in previous studies farther north in the subtropics and midlatitudes, save for larger integrated water vapor and weaker winds in the AR core and stronger equatorward vapor fluxes in the shallow post-cold-frontal northeasterly flow. Eight dropsondes released in a ~200-km-wide box formation provided a novel kinematic assessment of tropospheric vorticity, divergence (mass, water vapor, sensible heat), and vertical velocity in the AR region, as well as sea surface fluxes. The budget-box diagnostics were physically consistent with global-gridded reanalysis datasets, while also providing useful additional kinematic and thermodynamic information on the mesoscale. Meteorological impacts of the AR were assessed on Hawaii’s island of Kauai, where the state’s heaviest rainfall was observed for this case. Rainfall on Kauai was modulated significantly by its steep orography, including on the normally dry side of the island where heavy rains fell.

A personal use copy of the article is available here.

Publication Notice: Chemical properties of insoluble precipitation residue particles

CW3E Publication Notice

Chemical properties of insoluble precipitation residue particles

Jessie Creamean posing for a photo while clearing snow from the top of the NOAA trailer at Sugar Pine Dam after the storm on 2/25/11.

This article provides an in-depth analysis of resuspended residues from precipitation samples collected at a remote site in the Sierra Nevada Mountains in California during the 2009-2011 winter seasons. These residues may be used as a benchmark for classification of insoluble precipitation. Knowledge of the precipitation chemistry of insoluble residues coupled with meteorological and cloud microphysical measurements will ultimately improve our understanding of the link between aerosols, clouds, and precipitation.

This paper represents a significant milestone from the CalWater experiment, which is led by members of UCSD/Scripps’ new Centers on aerosols (CAICE) and extreme events (CW3E), as well as NOAA, DOE, NASA, USGS. It also highlights the multi-disciplinary research stimulated by CalWater, and the partnerships between key researchers across organizations. The lead author, Jessie Creamean, received her PhD in atmospheric chemistry from UCSD under Kim Prather using CalWater data, and is now bringing that expertise to a primarily meteorological group in NOAA as she pursues emerging topics in aerosol-precipitation interactions in collaboration with CW3E scientists.

A personal use copy of the article is available here.

CalWater-ACAPEX 2015 Planning Workshop

CalWater-ACAPEX 2015 Planning Workshop

Scripps Institution of Oceanography

La Jolla, California

CalWater 2 Co-Leads: Marty Ralph, Kim Prather, Dan Cayan (Scripps)

Organizing Committee: Chris Fairall (NOAA), Ruby Leung (PNNL), Andrew Martin (Scripps), Ryan Spackman (NOAA/STC)

CalWater2 – ACAPEX Observational Strategy Winter 2014-15

CalWater-2 took major steps from vision to reality on 22-24 April 2014 at Scripps Institution of Oceanography when roughly 40 key individuals (scientists, engineers, aircraft and ship managers, and students) met to plan for major field deployments in 2015. The following facilities are committed (or nearly so) to a field campaign between roughly 10 January and 10 March 2015:

  • DOE – G-1 aircraft
  • DOE AMF-2 ocean-atmosphere facility on the NOAA Research Vessel (ship) Ron Brown
  • NOAA G-IV aircraft
  • NOAA P-3 aircraft
  • ATOFMS mobile, land-based aerosol-sensor suite
  • EFREP hydrometeorological Mesonetwork in California

The DOE facilities are part of the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) experiment addressing (1) aerosol impacts on clouds and precipitation and (2) atmospheric rivers. The NOAA facilities were requested also based on the CalWater vision, with an emphasis on atmospheric-river science questions.

The workshop concluded with a plan for specific start and end dates for each facility, narrowed options for where to operate them, a plan for a field operations center (and a specific possible location), strategies for developing coordinated ship and aircraft operations, and plans for the forecasting capabilities needed to guide missions. In addition, the 12-member CalWater Core Scientific Steering Group met afterword and reviewed plans for 2016-2018 and strategies to advance the longer term Calwater Vision. The Steering Group committed to organizing two special sessions and a side meeting (for last minute coordinations of the 2015 CalWater and ACAPEX activities) at the Fall Meeting of AGU in December 2014, and a journal article describing the program. The proposed AGU sessions are:

  1. CalWater Theme 1: Cloud-Aerosol-Precipitation Interactions in California (Conveners: Daniel Rosenfeld, Kimberly Prather),
  2. Atmospheric Rivers: Observations, Dynamics, Modeling, Impacts and Applications (Conveners: Marty Ralph, Duane Waliser, Jason Cordeira).

The presentations from the Workshop are available here.

Workshop Sponsored by:

  • Scripps, Center for Western Weather and Water Extremes (CW3E)
  • Scripps Center for Aerosol Impacts on Climate and the Environment (CAICE)
  • Science and Technology Corporation (STC)

Workshop Sponsored by:Workshop Participants

Photo of most workshop participants at the CalWater 2015 – ACAPEX workshop at Scripps, April 2014.

CalWater2 Workshop Participants