CW3E AR Outlook: 14 December 2017 Ridge Update

CW3E AR Outlook: 14 December 2017 Ridge Update

December 14, 2017

Click here for a pdf of this information.

Dry Conditions Expected to Persist over CA for the Foreseeable Future

  • Persistent high pressure and ridging over the northeast Pacific and USWC is directing moisture transport towards AK and resulting in long periods of dry conditions over the USWC
  • The lack of precipitation over the southern USWC is increasing drought conditions and has resulted in the Northern Sierra 8-station index dropping below normal accumulations to date
  • While ridging is forecast to persist, AR conditions are currently forecast to impact the West Coast but the unfavorable north/northwesterly orientation of IVT will result in little or no precipitation over CA
  • Click IVT or IWV image to see loop of 0-180 hour GFS forecast

    Valid 1200 UTC 14 December – 0000 UTC 22 December 2017

    Click 500-hPa Geopotential Height & Vorticity image to see loop of 0-180 hour GFS forecast

     

     

     

     

     

     

    Summary provided by C. Hecht, J. Cordeira B. Kawzenuk, J. Kalansky, and F.M. Ralph; 1 PM PT Thursday 14 December 2017

    *Outlook products are considered experimental

CW3E AR Update: 17 November 2017 Outlook and Summary

CW3E AR Update: 17 November 2017 Outlook and Summary

November 17, 2017

Click here for a pdf of this information.

Strong AR recently made landfall over northern California

  • The AR reached its strongest magnitude of ~750 kg m-1 s-1 at ~6 PM PST over northern California making this a strong AR
  • IWV values within the AR ranged from 34–40 mm during the event
  • A second AR is forecast to make landfall over the USWC between 19 and 21 November 2017
  • The AR is currently over Southern California bringing precipitation to the Los Angeles area
  • Another AR is forecast to impact the USWC in the next several days

SSMI/SSMIS/AMSR2-derived Integrated Water Vapor (IWV)

Valid 0000 UTC 15 November – 1600 UTC 17 November 2017

Images from CIMSS/Univ. of Wisconsin

Click IVT or IWV image to see loop of GFS Analysis

Valid 0000 UTC 15 November – 1200 UTC 17 November 2017


 

 

A potentially extreme AR is forecasted to make landfall over the U.S. West Coast next week

  • The current AR impacting Southern California is forecast to end by later tonight
  • Multiple systems are forecast to bring potentially strong to extreme and prolonged AR conditions to the USWC
  • As much as 19 inches of precipitation could fall over the Olympic Mountains over the next week
  • Multiple rivers in Washington are currently forecast to rise above flood stage

Click IVT or IWV image to see loop of 0-180 hour GFS forecast

Valid 1200 UTC 17 November – 0000 UTC 25 November 2017

 

 

 

 

 

 

Summary provided by C. Hecht, B. Kawzenuk, J. Kalansky, and F.M. Ralph; 3 PM PT Friday 17 November 2017

*Outlook products are considered experimental

CW3E AR Update: 8 November 2017 Outlook

CW3E AR Update: 8 November 2017 Outlook

November 8, 2017

Click here for a pdf of this information.

Two ARs Forecasted to Make Landfall over the U.S. West Coast in the Next Week

  • A strong AR is currently making landfall over the U.S. West Coast
  • This AR is expected to produce up to 6 inches of precipitation over northern CA
  • The southerly orientation of this AR will result in the heaviest precipitation over the north Central Valley
  • A second, moderate strength, AR is forecasted to make landfall over northern CA, OR, and WA on 12 November 2017
  • The second AR is expected to make landfall further north resulting in the highest precipitation over the Olympic and Cascade

Click IVT or IWV image to see loop of 0-168 hour GFS forecast

Valid 1200 UTC 8 November – 1200 UTC 15 November 2017


 

 

 

 

 

Summary provided by B. Kawzenuk, J. Kalansky, and F.M. Ralph; 12 PM PT Wednesday 8 November 2017

*Outlook products are considered experimental

CW3E AR Update: 3 November 2017 Outlook

CW3E AR Update: 3 November 2017 Outlook

November 3, 2017

Click here for a pdf of this information.

Two systems expected to produce precipitation over the U.S. West Coast in the next week

  • AR conditions (IVT >250 kg m-1 s-1 and IWV >20 mm) are expected over most of CA over the next four days
  • While AR conditions are forecast for some locations of the USWC, this event is not necessarily an AR due to geometric and spatial structure, but could produce up to 5 inches of precipitation and some snow over the Sierra Nevada
  • A potentially strong AR is expected to make landfall over CA, OR, and WA on 8 November 2017
  • The highest amounts of precipitation are expected over the coastal ranges of CA and OR
  • The AR is currently expected to have a southerly orientation which will result in less extreme precipitation

Click IVT or IWV image to see loop of 0-180 hour GFS forecast

Valid 1200 UTC 3 November – 0000 UTC 11 November 2017


 

 

 

 

 

 

 

Summary provided by B. Kawzenuk, J. Kalansky, C. Hecht, and F.M. Ralph; 3 PM PT Friday 3 November 2017

*Outlook products are considered experimental

CW3E AR Update: 18 October 2017 Outlook

CW3E AR Update: 18 October 2017 Outlook

October 18, 2017

Click here for a pdf of this information.

Multiple ARs forecast to Impact U.S. West Coast

  • A potentially extreme AR is forecast to make landfall over the Pacific Northwest today
  • NWS precipitation forecasts show accumulations of ~10 inches for the Olympic Mountains in northwest Washington
  • A second AR is forecast to make landfall on Saturday, though forecast uncertainty is currently high
  • Total 5-day precipitation accumulations could be as high as 15.5 inches
  • Current soil conditions are dry which could lead to less runoff and lower flooding potential

Click IVT or IWV image to see loop of 0-141 hour GFS forecast

Valid 0600 UTC 18 October – 0300 UTC 24 October 2017

For more information on the satellite imagery and the configuration click here

 

 

 

 

 

 

Summary provided by C. Hecht, B. Kawzenuk, and F.M. Ralph; 1 PM PT Wednesday 18 October 2017

*Outlook products are considered experimental

CW3E Publication Notice: The Chiricahua Gap and the Role of Easterly Water Vapor Transport in Southeastern Arizona Monsoon Precipitation

CW3E Publication Notice

The Chiricahua Gap and the Role of Easterly Water Vapor Transport in Southeastern Arizona Monsoon Precipitation

Spetember 13, 2017

Click here for personal use pdf file

This study is a collaborative effort between CW3E and University of Arizona that identifies a terrain feature along the Arizona-New Mexico border just north of Mexico that is potentially important to the weather and climate of the southeast Arizona summer monsoon. The terrain feature is a “gap” that is approximately 250 km across and 1 km deep and represents the lowest terrain elevation along the 3000-km length the Continental Divide from 16-45°N. The name “Chiricahua Gap” is introduced to identify this key terrain feature, which reflects the name of a nearby mountain range in southeast Arizona and the region’s Native American history. The importance of the Chiricahua Gap is that it represents the primary pathway in which low altitude atmospheric water vapor is transported across the Continental Divide.

Motivated by identification of the Chiricahua Gap, upper-air observations from a wind profiling radar in Tucson, model reanalyses (Climate Forecast System Reanalysis), and gridded daily precipitation data (NCEP Stage-IV) are used to construct a case study and 15-year climatology to link summer monsoon rainfall events in southeast Arizona to low-altitude water vapor transport within the Chiricahua Gap. The results show that 76% of the wettest summer monsoon days in southeast Arizona during 2002-2016 occurred in conditions of low-altitude easterly water vapor transport in the Chiricahua Gap on the previous day. This result highlights how low-altitude water vapor associated with the wettest summer monsoon days in southeast Arizona originates from the east side of the Continental Divide, which differs from previous studies published since the 1970s. Much of the recent scientific literature points to southwesterly surges of low-altitude water vapor from over the Gulf of California as the primary driver of rainfall over southern Arizona during the summer monsoon. The current study by F. M. Ralph and T. J. Galarneau shows that the source region of low-altitude water vapor in southeast Arizona during the summer monsoon is potentially more complex, and is significantly influenced by source regions east of the Divide.

The paper is an example of CW3E expanding its research to examine the dynamics of the North American monsoon. Because monsoon is an important source or water for the US southwest and can cause flooding events, particularly flash floods, better understanding and improving forecasts of the North American monsoon is and important component of CW3E achieving its goal of revolutionizing the physical understanding, observations, weather predictions, of extreme events in Western North America and their impacts on floods, droughts, hydropower, ecosystems and the economy.

Figure 1: Terrain height (shaded in m) over Arizona, New Mexico, western Texas, and northern Mexico. Key terrain features are labeled in black. The location of Tucson, Arizona, is labeled by the black-filled circle. Low-altitude easterly water vapor transport through the Chiricahua Gap is shown by the blue arrows. This figure is modified from Fig. 1b in Ralph and Galarneau (2017).

CW3E Undergraduate Researcher, Cody Poulsen, Awarded a SDEP Excellence Award

CW3E Undergraduate Researcher, Cody Poulsen, Awarded a SDEP Excellence Award

June 28, 2017

Cody Poulsen, an undergraduate student at UC San Diego pursuing a degree in Environmental Chemistry in the Environmental Systems (ESYS) Department and a minor in Digital Media, has collaborated on a research project with CW3E post-doc Scott Sellars. The project began during the summer of 2016 and was focused on using a program created by the Monterey Bay Aquarium Research Institute (MBARI) named Video Annotation Reference Systems (VARS) to produce useable meteorological metadata. VARS was created by MBARI to aid researchers in cataloguing the occurrences of biological species and geological formations in the large amounts of underwater footage collected by their ROVs. The research continued as part of Cody’s senior thesis during which he created an Atmospheric River metadata set with VARS. During the process, he learned more about the system and its capabilities. The metadata set is comprised of annotations for the location of AR landfall and center of AR events during the Water Years (WYs) 2001 and 2011. In addition, annotations for ARs with an associated Lower Level Jet (LLJ) structure where produced for both WYs. In the case study of WYs 2001 and 2011, the metadata depicted an anomalously high amount of landfalling AR events in California/Oregon for December 2010 juxtaposed to zero landfalling events along the North American West Coast excluding Alaska for December 2000. 500-hPa average wind speeds, heights, & direction plots for the two months where created to discern the general first principal flow that might explain the different AR trajectories. With these plots, it was found that a high-pressure ridge at 180° and low pressure trough at 140°W funneled ARs onto the California/Oregon coast for December 2010. Where December 2000 had a slight high pressure ridge along the coast to produce an insignificant blocking action leading to the assumption that some other synoptic features must be at play to produce the zero-event period.

For his senior thesis, Cody produced a poster on the VARS research project and presented it at the ESYS senior symposium. The symposium was comprised of poster presentations from each of the ESYS seniors that participated in research projects/ internships over their senior year. Cody and his research were selected by San Diego Environmental Professionals (SDEP) as one of the two projects to win an excellence award.

CW3E undergraduate researcher, Cody Poulsen, presents his research using VARS at the ESYS senior symposium.

CW3E AR Update: 06 June 2017 Outlook

CW3E AR Update: 06 June 2017 Outlook

June 06, 2017

Click here for a pdf of this information.

Update on Late Season AR Forecast to Impact West Coast This Week

  • Little change from yesterday’s forecast
  • Ensemble GFS members are still in good agreement of the onset, duration, and maximum magnitude of coastal IVT
  • NOAA WPC precipitation forecasts are predicting as much as 4.2 inches over the Coastal Mountains of Northern CA and OR
  • A few rivers in the Cascade Range of WA and OR are forecast to rise to action or flood stage due to melting snow and the landfalling AR

Click IVT or IWV image to see loop of 0-114 hour GFS forecast

Valid 1200 UTC 06 June – 0600 UTC 11 June 2017


 

 

 

 

 

 

Summary provided by C. Hecht and F.M. Ralph; 12 PM PT Tuesday 06 June 2017

CW3E AR Update: 05 June 2017 Outlook

CW3E AR Update: 05 June 2017 Outlook

June 05, 2017

Click here for a pdf of this information.

Late Season AR Forecast to Impact West Coast

  • An unseasonably strong AR is forecast to impact the Pacific Northwest and Northern CA over the next couple of days
  • As much as 4.1 inches of precipitation is forecast to fall over the higher elevations of the Coastal Mountains in CA and OR over the next week
  • With higher freezing levels forecast during landfall, there is a potential for rain on snow and increased runoff
  • Due to the combination of snowmelt and the landfalling AR, several rivers in the Pacific Northwest are forecast to rise above flood stage

Click IVT or IWV image to see loop of 0-114 hour GFS forecast

Valid 1200 UTC 05 June – 0600 UTC 10 June 2017


 

 

 

 

 

 

Summary provided by C. Hecht and F.M. Ralph; 1 PM PT Monday 05 June 2017

CW3E Update: Flood Risk From Snow Melt

CW3E Update: Flood Risk From Snow Melt

May 23, 2017

Click here for a pdf of this information.

Anomalously Warm Temperatures Expected to Contribute to Melting Snowpack and Elevated Runoff

  • High temperatures of 60–80˚F (16–26˚F) are forecast for the higher elevations of the Sierra Nevada Mountains over the next several days
  • The higher than normal water year to date precipitation over much of the West Coast has created snow packs that are much greater than normal over most of the Sierra Nevada Mountains
  • The combination of anomalously high temperatures and snow pack is forecast to lead to increased runoff and potential flooding
  • The National Weather Service has issued flood watches and warnings for several locations in California
  • Loop of GFS Forecast Surface Temperatures

    Valid 1200 UTC 23 May – 1200 UTC 30 May 2017


     

     

     

    Summary provided by C. Hecht B. Kawzenuk and F.M. Ralph; 12 PM PT Tuesday 23 May 2017