CW3E AR Update: 28 February 2024 Outlook

CW3E AR Update: 28 February 2024 Outlook

February 28, 2024

Click here for a pdf of this information.

AR and Low Pressure-System to Produce Heavy Rain and Snow over USWC

  • An atmospheric river (AR) and low-pressure system will bring widespread precipitation to the US West Coast over the next several days, including very heavy snowfall in the Sierra Nevada.
  • The AR has made landfall over the PNW and is forecast to move down the USWC through Fri 1 Mar.
  • Behind this AR, the associated low pressure system and a mid-level trough will help continue this precipitation event over CA through Sun 3 Mar.
  • There is potential for a pulse of IVT from the central Pacific to reach the USWC and extend AR conditions and precipitation duration over northern and central CA.
  • The NWS Weather Prediction Center (WPC) is forecasting significant precipitation over the next 5 days along the WA through N. CA coasts and over the Cascades and Sierra Nevada.
  • The National Blend of Models (NBM) is showing very high probabilities (>90%) of snowfall exceeding 48 inches for portions of the Sierra Nevada, with accumulations forecast to potentially exceed 80 inches.
  • West-WRF Ensemble meteograms are also showing very high probabilities of significant snowfall (totals > 48 inches) in the Sierra Nevada.
  • The WPC Excessive Rainfall Outlooks include a Marginal Risk (level 1 of 4, or at least 5% chance) for flooding for the WA/OR/N. CA/S. CA coasts and the Sierra Nevada foothills with the the AR as it moves down the coast.
  • Stay alert to official NWS forecasts, watches, and warnings at weather.gov and follow guidance from local emergency management officials.

Click images to see loops of GFS IVT and IWV forecasts

Valid 1200 UTC 28 February 2024 – 1200 UTC 3 March 2024

Summary provided by M. Steen, C. Castellano, P. Iniguez, and S. Bartlett; 28 February 2024

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*Outlook products are considered experimental

For any unfamiliar terms, please refer to the American Meteorological Society Glossary.

CW3E AR Update: 26 February 2024 Outlook

CW3E AR Update: 26 February 2024 Outlook

February 26, 2024

Click here for a pdf of this information.

AR and Low Pressure System Fuel Precipitation Event Over USWC

  • An atmospheric river (AR) and low pressure system forecast to make landfall over the USWC will help fuel a multi-day precipitation event that is likely to bring heavy snowfall to the Cascades and Sierra Nevada.
  • The AR makes landfall over the PNW late on Tue 27 Feb and moves down the USWC through Fri 1 Mar.
  • There is potential for a pulse of IVT from the central Pacific to reach the USWC and extend AR conditions over northern and central CA when it interacts with AR.
  • Behind this AR, the associated low pressure system and a mid-level trough will help continue this precipitation event over CA through Sun 3 Mar.
  • The NWS Weather Prediction Center (WPC) is forecasting significant precipitation over the next 7 days along the WA/OR coasts and OR/CA border and over the Cascades and Sierra Nevada.
  • The National Blend of Models (NBM) showing very high probabilities (>90%) of snowfall exceeding 36+ in. for portions of the Cascades and Sierra Nevada.
  • West-WRF Ensemble Meteograms are also showing very high probabilities of significant snowfall (totals > 24 in.) in the Sierra Nevada.
  • The WPC Excessive Rainfall Outlooks include a Marginal Risk (level 1 of 4, or at least 5% chance) for flooding for the WA/OR/N. CA coasts and the N. Sierra Nevada with the the AR as it moves down the coast.
  • Stay alert to official NWS forecasts, watches, and warnings at weather.gov and follow guidance from local emergency management officials.

Click images to see loops of GFS IVT and IWV forecasts

Valid 1200 UTC 26 February 2024 – 0000 UTC 3 March 2024

Summary provided by M. Steen, P. Iniguez, S. Bartlett and G. Lewis; 26 February 2024

To sign up for email alerts when CW3E post new AR updates click here.

*Outlook products are considered experimental

For any unfamiliar terms, please refer to the American Meteorological Society Glossary.

CW3E AR Update: 16 February 2024 Outlook

CW3E AR Update: 16 February 2024 Outlook

February 16, 2024

Click here for a pdf of this information.

Pair of Storms to Bring Precipitation to California

  • A pair of storms are forecast to impact the US West Coast during the next several days.
  • The first storm is an atmospheric river (AR) that makes landfall across the USWC on Fri 16 Feb.
  • The landfall orientation of the this AR is likely to be suboptimal for orographic precipitation, potentially limiting the precipitation potential of this system.
  • The second storm is a second AR that is forecast to make landfall alongside a low pressure system into central CA on Sun 18 Feb.
  • The second system taps into remnant moisture from the first system, which combined with the persistence of the stationary low pressure system off the CA coast, will result in a multi-day precipitation event for the state.
  • The NWS Weather Prediction Center (WPC) is forecast significant precipitation over the next 7 days along the northern and central CA coasts and in the Sierra Nevada.
  • The WPC Excessive Rainfall Outlook (ERO) indicates a Slight Risk (level 2 of 4, or at least 15% chance) for flooding over the northern CA coast with the first storm and along the northern and central CA coasts with the second storm.
  • The WPC ERO also indicates a Marginal Risk (level 1 of 4, or at least 5% chance) for flooding across broader areas.
  • The second storm is likely to bring heavy snowfall to the Sierra Nevada. The National Blend of Models (NBM) indicates very high probabilities (>90%) of snowfall accumulations exceeding 24”.

Click images to see loops of GFS IVT and IWV forecasts

Valid 1200 UTC 16 February 2024 – 1200 UTC 21 February 2024

Summary provided by M. Steen, P. Iniguez, S. Bartlett and C. Castellano; 16 February 2024

To sign up for email alerts when CW3E post new AR updates click here.

*Outlook products are considered experimental

For any unfamiliar terms, please refer to the American Meteorological Society Glossary.

CW3E Researcher Agniv Sengupta selected for AMS ECLA

CW3E Researcher Agniv Sengupta selected for AMS ECLA

February, 15 2024

CW3E scientist, Dr. Agniv Sengupta, was selected as a member of the American Meteorological Society’s Early-Career Leadership Academy Class of 2023. “The American Meteorological Society’s (AMS) Early Career Leadership Academy (ECLA) aims to build and sustain a diverse network of early career leaders in weather, water, and climate science. ECLA will bring together a select group of early career individuals—in particular, women and underrepresented minorities—for an immersion experience in leadership, such as creative problem-solving, conflict resolution, building trust, and enhancing communication skills. We seek early career individuals from a wide range of professions, interests, perspectives, cultures, and experiences.” (from AMS’s website ).


Group photo of the members of the 2023 AMS ECLA Cohort

This professional development program included four virtual leadership webinars and several peer mentoring calls, leading up to a three-day, in-person summit in Phoenix, Arizona. Webinars for the 2023 ECLA program began with participants taking an individual leadership assessment using the CliftonStrengths test. This assessment helped them identify personalized traits in strategic thinking, influencing, relationship building, and executing. The webinars also covered conflict management and resolution, as well as providing comprehensive diversity, equity, and inclusion (DEI) training with dedicated reading and writing exercises.

During the in-person workshop, participants heard from several invited keynote speakers who shared their leadership journeys and how they navigated various societal and professional challenges. The workshop also included sessions on constructing personal leadership styles, research ethics, team building, enhancing communication skills, and bystander practice and intervention using real-life scenarios.

Dr. Sengupta expresses his appreciation to the AMS for developing ECLA and to the Planning Committee for their hard work in creating an immersive experience for the cohort. He found the overall experience enriching as it provided fresh perspectives, insights into unique leadership styles, and a high-quality, diverse network of peers and mentors. Dr. Sengupta highly recommends this career development opportunity to early-career scientists interested in leadership positions in the future.


Photo of the peer-mentor group of Dr. Sengupta from the ECLA workshop

CW3E AR Update: 14 February 2024 Outlook

CW3E AR Update: 14 February 2024 Outlook

February 14, 2024

Click here for a pdf of this information.

Trio of Storms to Bring Precipitation to California

  • A trio of storms are forecast to make landfall over the US West Coast in the next 7 days.
  • The first storm is driven by a low pressure system that brings a burst of IVT to the USWC on Wed 14 Feb. This low pressure system persists off the PNW coast through Thu 15 Feb as the second AR propagates toward the USWC.
  • The second storm is an atmospheric river (AR) that makes landfall across the USWC on Fri 16 Feb. The landfall direction of the AR is likely to be suboptimal for precipitation, potentially limiting the precipitation potential of this system.
  • The ECMWF EPS is forecasting greater probabilities of IVT > 250 kg m-1 s-1 making landfall over the PNW with the second AR than the GEFS.
  • The third storm is a second AR that is forecast to make landfall alongside a low pressure system into central CA on Sun 18 Feb.
  • There is uncertainty amongst GEFS and EPS ensemble members regarding the duration and strength of AR conditions with the second and third ARs across CA.
  • The WPC is forecasting significant 7 day precipitation over the northern and central CA coasts and the Sierra Nevada.
  • The WPC Excessive Rainfall Outlook indicates a Slight Risk (level 2 of 4, or at least 15% chance) for flash flooding over the northern CA coast for the 24 hour period ending 4 AM PT Sun 18 Feb with the second AR.
  • The NWS WPC has issued Excessive Rainfall Outlooks highlighting the potential for flash flood conditions in various locations along the coast of California in association with precipitation during each of the three storms during this period.

Click images to see loops of GFS IVT and IWV forecasts

Valid 1200 UTC 14 February 2024 – 0000 UTC 22 February 2024

Summary provided by M. Steen, S. Bartlett and P. Iniguez; 14 February 2024

To sign up for email alerts when CW3E post new AR updates click here.

*Outlook products are considered experimental

For any unfamiliar terms, please refer to the American Meteorological Society Glossary.