Map illustrating the trajectories of atmospheric rivers (ARs) that made landfall along the U.S. West Coast between October 2025 and March 2026. The arrow endpoint indicates the coastal location where the highest integrated vapor transport (IVT) within each AR was observed based on ERA5 reanalysis. The color shading indicates the maximum IVT magnitude [in kg/(ms)] of each AR along the coast.

56 #AtmosphericRivers made landfall along the U.S. West Coast during the first 6 months of Water Year 2026. There were stark differences in AR activity between October-December (14 strong or greater ARs) and January-March (3 strong ARs).

Read the full summary here: cw3e.ucsd.edu/the-atmosphe....

A graphic including the title of Bartlett et al. 2026, Figure 4 from Bartlett et al. 2026, and a bottom bar with the CW3E, UCSD, and SIO logos.

CW3E Publication Notice: "A Climatological and Keyword-Based Analysis of National Weather Service Mesoscale Precipitation Discussions" was recently published in the @nwas.org Journal of Operational Meteorology.

Read more about this research here: cw3e.ucsd.edu/cw3e-publica...

Left: NWS Stage IV total estimated precipitation for the 4-day period ending 5 AM PDT 13 April 2026. Right: NWS total estimated snowfall for the 4-day period ending 5 AM PDT 13 April 2026.

A late-season storm brought low-elevation rain and heavy mountain snow to northern and central California last weekend.

See our latest Quick Summary for more details: cw3e.ucsd.edu/wp-content/u....

Comparison of vertical velocity differences and topographic features (low-resolution). (a) Vertical velocity difference: adaptive mesh refinement (AMR) mesh–Fixed mesh; (b) Vertical velocity difference: AI mesh–Fixed mesh; (c) Elevation at y = 80 km and (d) Slope difference (AMR–Fixed) at y = 80 km comparing results from the fixed mesh and adaptive mesh. From Figure 9 in Gan et al. (2026).

CW3E Publication Notice: "Tibetan Plateau Mountain Wave Simulation Using AI-Driven 3D Adaptive Mesh Refinement" in @agu.org's Journal of Geophysical Research: Atmospheres.

For a summary of this paper, visit cw3e.ucsd.edu/cw3e-publica....

Antarctic air temperature trends from station temperature reconstruction (RECON) and CMIP6. Spatial map of annual and seasonal surface air temperature (SAT) trends from 1958 to 2022 based on station temperature reconstruction (RECON; a,c,f,h,e) and CMIP6 multi-model Mean (MMM; b,d,g,i,j). The dot pattern represents trends that are significantly different from zero at P < 0.05 after removing the impact of autocorrelation from the residuals. From Figure 1 in Bromwich et al. (2026).

CW3E Publication Notice: "Interior Antarctica is undergoing marked climate change" in @nature.com's Communications Earth & Environment.

For a summary of this paper, visit cw3e.ucsd.edu/cw3e-publica....

Three-dimensional trajectories of temperature and moisture for two representative atmospheric river events. Nine-hour backward trajectories that initialized 2 m above the Larsen C Ice Shelf (LCIS) surface of (a,c) zonal-perpendicular and (b,d) convex events, occurring in Dec 2008 and Feb 2013 respectively, and based on PWRF simulations. (a,c) trajectories showing temperature (°C) and water vapor mixing ratio changes (g/kg) from 00Z to 09Z on 3 Dec. (b,d) as (a,c) but from 00Z to 09Z on 3 Feb. LCIS in (a) refers to the Larsen C Ice Shelf. All values are archived in the source data. From Figure 6 in Zou et al. (2026).

CW3E Publication Notice: "Föhn-Induced Melting over Larsen C Modulated by Atmospheric River Shape, Direction, and Landfall Location" in @nature.com's Nature Communications.

For a summary of this paper, visit: cw3e.ucsd.edu/cw3e-publica....

Page one of the quick look featuring forecast highlights.

Page two of the quick look. On top are 500-hPa vorticity forecasts from the CW3E's West-WRF initialized with the ECMWF. On the bottom left are model forecast plumes for precipitation over the Upper Yuba watershed for the next 10 days. Bottom right are two streamflow forecasts from the CNRFC for gauges along the Cosumnes River.

Page three of the quick look. On top are 24-hour precipitation forecast from the WPC and a 72-hour accumulation period ending early Monday 13 April from the WPC. On the bottom left is the day 3 categorical severe weather outlook from the WPC. On the bottom right is a simulated reflectivity forecast from CW3E's West-WRF initialized with the ECMWF.

Page four of the quick look. On the top left is EPS probability of total snowfall greater than or equal to 12 inches by early Monday 13 April. On the top right are EPS freezing level forecasts for the Upper San Joaquin watershed. On the bottom right is basin snow water equivalent with respect to the climatological mean. On the bottom right is three month precipitation as the percent of normal.

A cutoff low and shortwave trough are forecast to bring rain and potential snowfall along with cooler temperatures to California between Friday 10 April and Monday 13 April.

See our latest quick look for more details: cw3e.ucsd.edu/wp-content/u...

CW3E has prepared an event summary detailing the series of named storms and #AtmosphericRivers that fueled well above normal precipitation to the Iberian Peninsula between January and February, 2026. Read our analysis here: cw3e.ucsd.edu/cw3e-event-s...

Top Panel: A short-range X-Band radar is installed on Rocky Ridge in western Contra Costa County, California on December 8, 2022. It’s one of six new radars that form the foundation for a forecast system designed to improve prediction of heavy rainfall and runoff in the Bay Area. Credit: Contra Costa County Public Works, Flood Control Division Bottom Panel: A map that depicts the coverage offered by the AQPI radar array over the San Francisco Bay area.

CW3E Works With Partners to Make Advanced Quantitative Precipitation Information (AQPI) System Fully Operational. Read the full @noaa.gov Press Release here: research.noaa.gov/groundbreaki...

The main body page of the Quick Look containing bulleted points on the forecast discussion.

The second page of the Quick Look containing forecast graphics for the Northeast Pacific

A third page of forecast graphics containing AR Scale forecasts and precipitation forecasts.

A fourth page of graphics containing watershed precipitation forecast graphics and freezing level forecast graphics.

Check out our latest Quick Look at the pattern shift forecast to occur next week over the Western US, with the potential for cooler and wetter conditions. Read more here: cw3e.ucsd.edu/wp-content/u...

An advertisement for a seminar by CW3E Director Marty Ralph at the University of Maryland featuring his photo and details about the seminar.

CW3E Director Marty Ralph will present a seminar at the Earth System Science Interdisciplinary Center at the University of Maryland on Monday, March 30 titled “Atmospheric Rivers: From Science to Solutions.” To attend this seminar in person or virtually, visit: essic.umd.edu/events/marty...

Left: GEFS maximum observed coastal AR Scale analysis for the 7-day period ending 5 PM PDT 21 Mar 2026. Center: GEFS control AR Scale and IVT analyses for the 7-day period ending 5 PM PDT 21 Mar 2026 at 46.5°N, 124°W. Right: NWS Stage IV total estimated precipitation for the 6-day period ending 5 AM PDT 21 Mar 2026.

A long-duration #AtmosphericRiver produced moderate-to-heavy rainfall and flooding in portions of Washington last week.

See our latest Quick Summary for more details: cw3e.ucsd.edu/wp-content/u....

Page 1 of Quick Look. Summary of key forecast information.

Page 2 of Quick Look. Top: GFS 500-hPa geopotential height (contours) and 500-hPa geopotential height standardize anomaly (shading) forecasts valid at 5 AM PDT Fri 20 Mar (left) and 11 PM PDT Tue 24 Mar (right). Bottom: National Weather Service (NWS) experimental HeatRisk forecasts valid for Fri 20 Mar (left) and Wed 25 Mar (right).

Page 3 of Quick Look. Top: PRISM month-to-date (1-19 Mar) daily mean temperature anomalies. Middle: Basin snow water equivalent percent of 1991-2020 median valid on 1 Mar (left) and 19 Mar (right). Bottom: California-Nevada River Forecast Center (CNRFC) forecast peak runoff date for water year 2026 (left), average peak peak runoff date for 1991-2020 (center), and water year 2026 departure from average in days (right).

Page 4 of Quick Look. Top: West-WRF GFS integrated vapor transport (IVT; shading) and sea-level pressure (SLP, contours) forecasts valid at 11 PM PDT Sun 22 Mar (left) and 11 PM PDT Mon 23 Mar (right). Bottom: Comparison of IVT and SLP forecasts from West-WRF GFS (left) and West-WRF ECMWF (right) valid at 11 AM PDT Tue 24 Mar.

Unseasonably warm and dry conditions will persist over much of the southwestern US into next week, while another #AtmosphericRiver is forecast to impact the Pacific Northwest.

See our latest Quick Look for more details: cw3e.ucsd.edu/wp-content/u....

A page with bulleted text describing the forecast atmospheric river over the Pacific Northwest and it's associated impacts in the coming days.

A page including figures that describe the progression of the AR using IVT maps and CW3E's AR Scale graphics describing the ensemble AR Scale forecasts associated with this event.

A page including CW3E's AR Landfall graphic highlighting the probability of AR conditions along the US West Coast and CW3E's QPF graphics highlighting 24-hour and 72-hour QPF forecast from the NWS WPC, with excessive rainfall outlooks overlaid on top.

A page including graphics from the NWS Northwest River Forecast Center highlighting locations forecast to experience flood conditions over the next 10 days. Also included are a median snowpack graphic and a forecast temperature map, highlighting the impacts of warm temperatures on the overall Western US snowpack.

A long-duration #AtmosphericRiver will continue to impact the Pacific Northwest through early Saturday, with flooding expected in western Washington. Check out our latest Quick Look for additional information or visit: cw3e.ucsd.edu/wp-content/u...

A slide including the title of the article and Figure 5 from Tallapragada et al. 2026 in the Journal of Geophysical Research: Atmospheres

CW3E Publication Notice: "Evaluation of GFSv16 for Near-Real-Time Data Impact Studies During the Atmospheric River Reconnaissance Program 2022" in the @agu.org Journal of Geophysical Research: Atmospheres.

To read a summary of this article, visit: cw3e.ucsd.edu/cw3e-publica...

A long-duration #AtmosphericRiver will bring moderate-to-heavy rainfall to portions of western Washington this week. Riverine flooding is possible due to the combination of snowmelt and rain at higher elevations.

See our latest AR Outlook for more information: cw3e.ucsd.edu/cw3e-ar-upda....

Ensemble guidance is showing high confidence in a prolonged period of #AtmosphericRiver conditions over the PNW beginning this weekend and continuing through next week, with potential for heavy rain in WA from this event.

See our latest AR outlook for more details: cw3e.ucsd.edu/cw3e-ar-upda...

Page 1 of Quick Look. Summary of key forecast information.

Page 2 of Quick Look. Top Left: West-WRF integrated water vapor transport (IVT; shading), and sea-level pressure (SLP; contours) initialized 5 AM PT 11 Mar - F006. Top right: Same as top left but for F024. Bottom left: Same as top left but for F042. Bottom right: Same as top left but for F060.

Page 3 of Quick Look. (Top) GEFS ensemble probability of AR conditions [IVT≥250 kg/(ms)] along the West Coast of North America for the 16-day period valid 5 AM PT Wed 11 Mar through 5 AM PST Fri 27 Mar. (Bottom) CW3E 200-member West-WRF 7-day control and ensemble AR Scale and IVT forecasts for 46.5°N, 124°W (coastal southern Washington).

Page 4 of Quick Look. Top: NWS Weather Prediction Center (WPC) excessive rainfall outlooks (EROs) valid for the 24-hour periods ending 5 AM PT Thu 12 Jan, Fri 13 Jan, and Sat 14 Jan. Bottom left: WPC Total quantitative precipitation forecast (QPF) valid for the 7-day period ending 5 AM PT Sat 14 Mar. Bottom right: GEFS ensemble freezing level and WPC 6-hourly QPF forecasts in the Duwamish watershed for the 7-day period ending 11 PM PST Wed 18 Mar.

A long-duration #AtmosphericRiver is forecast to bring heavy rain and snow to portions of the Pacific Northwest this week with additional AR activity possible next week. See our latest Quick Look for more information: cw3e.ucsd.edu/wp-content/u...

Multiple #AtmosphericRivers are forecast to bring heavy rain and snow to the Pacific Northwest this week into early next week.

See our latest AR Outlook for more details: cw3e.ucsd.edu/cw3e-ar-upda....

A title slide depicting the graphical abstract for Gan et al. 2026 in the Journal of Computational Physics.

CW3E Publication Notice: "HyMeshAI: Deep learning enabled three-dimensional adaptive mesh generator for high-resolution atmospheric simulations" was recently published in the Journal of Computational Physics.

Read more about this research here: cw3e.ucsd.edu/cw3e-publica...

A title slide displaying Figure 1 from Giglio et al. 2025, published in the AGU's Geophysical Research Letters.

CW3E Publication Notice: "Adaptive Sampling of the Upper Ocean by Autonomous Floats During Atmospheric River Precipitation" in @agu.org's Geophysical Research Letters.

Visit our website to read more about this research: cw3e.ucsd.edu/cw3e-publica...

An introductory slide for this article highlighting Figure 3 from Taylor et al. 2026 as published in the Journal of Water Resources Planning and Management

CW3E Publication Notice: "Comparing the Robustness of Forecast-Informed Reservoir Operating Policies under Forecast Uncertainty and Hydrologic Extremes" in the Journal of Water Resources Planning and Management.

Read more about this research on our website here: cw3e.ucsd.edu/cw3e-publica...

A introductory slide showing the title of this article and Figure 14 from Gibson et al. 2026

CW3E Publication Notice: "Emerging trends in landfalling atmospheric rivers over the South Pacific" was recently published in npj Climate and Atmospheric Science.

Visit our website to read more about this research: cw3e.ucsd.edu/cw3e-publica...

A cover slide including the title of the article and the graphics for Figure 2 from Zou et al. (2026), Frontiers in Earth Science.

CW3E Publication Notice: "Antarctica’s uncertain future: sea-level rise from oceanic and atmospheric forcing, with a focus on atmospheric rivers" in Frontiers in Earth Science.

To read more about this research visit: cw3e.ucsd.edu/cw3e-publica...

CW3E Publication Notice: Several papers investigating the impacts of #AtmosphericRivers on cloud radiative effects in both the Arctic and Antarctic have recently been published.

Read more about these publications here: cw3e.ucsd.edu/cw3e-publica...

CW3E Publication Notice: "Antecedent moisture enhances early warning of atmospheric river flood hazards" in Nature Communications.
Read more about this research here: cw3e.ucsd.edu/cw3e-publica...

A low pressure system and an #AtmosphericRiver brought heavy precipitation to western Oregon and Northern California and snow over the Cascades and Bitterroot Ranges.

See our latest Quick Summary for more information: cw3e.ucsd.edu/wp-content/u....

North American Universities Support Global Expansion of Atmospheric River Science Program A program focused on key storm systems, known as atmospheric rivers, that provides students with hands-on research experience, launched its second season in January.

🌎 1️⃣ 6️⃣ teams represented by students from universities across North America are teaming up to collect observations to improve global #AtmosphericRiver forecasts. Learn more about the initiative led by @cw3escripps.bsky.social. ⤵️

Left: Total estimated precipitation for the 5-day period ending 4 AM PST Fri 20 Feb based on the National Weather Service (NWS) Stage IV product. Center: Total estimated snowfall for the same period based on the NWS National Operational Hydrologic Remote Sensing Center (NOHRSC) snowfall analysis product. Right: NWS local storm reports received during the same period, color-coded by category.

Multiple winter storms brought heavy rain and snow to California last week. Portions of the Sierra Nevada received more than 6 feet of total snow.

See our latest Quick Summary for more information: cw3e.ucsd.edu/wp-content/u....

Page 1 of Quick Look. Summary of key forecast information.

Page 2 of Quick Look. Top left: West-WRF integrated water vapor (IWV; shading), sea-level pressure (SLP; contours), and 850-hPa wind (barbs) forecasts valid at 10 PM PST Mon 23 Feb. Top right: West-WRF integrated vapor transport (IVT; shading and vectors) and SLP (contours) forecasts valid at 4 PM PST Mon 23 Feb. Bottom left: West-WRF IWV (shading), SLP (contours), and 850-hPa wind (barbs) forecasts valid at 10 PM PST Tue 24 Feb. Bottom right: West-WRF IVT (shading and vectors) and SLP (contours) forecasts valid at 10 PM PST Tue 24 Feb.

Page 3 of Quick Look. Top left: West-WRF control maximum AR Scale forecasts along the coast for the 7-day period ending 4 PM PST Sun 1 Mar. Top right: West-WRF control and ensemble AR Scale and IVT forecasts at 41°N, 124°W (Humboldt County) valid for the same time period. Bottom left: NWS Weather Prediction Center (WPC) Day 1 quantitative precipitation forecast (QPF) and excessive rainfall outlook (ERO) for the 24-hour period ending 4 AM PST Tue 24 Feb. Bottom center: NWS WPC Day 2 QPF and ERO for the 24-hour period ending 4 AM PST Wed 25 Feb. Bottom right: NWS WPC total QPF for the 48-hour period ending 4 AM PST Wed 25 Feb.

Page 4 of Quick Look. Top left: Map showing the percent of total 7-day precipitation forecast to fall as rain and/or snow (shading) in different watersheds based on forecasts from the GEFS ensemble. Top right: GEFS 7-day ensemble freezing level forecasts (lines) and WPC 6-hourly mean areal QPF (bars) for the Upper Yuba watershed. Bottom left: 10-day river stage forecasts issued by the Northwest River Forecast Center (NWRFC). Bottom right: 5-day river stage forecasts issued by the California-Nevada River Forecast Center (CNRFC).

A strong #AtmosphericRiver fueled by tropical and subtropical moisture will bring heavy rain to portions of the Pacific Northwest and California today and tomorrow.

See our latest Quick Look for more information: cw3e.ucsd.edu/wp-content/u....