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CW3E Scripps
@cw3escripps.bsky.social
720 followers 3 following 120 posts
The Center for Western Weather and Water Extremes of Scripps Institution of Oceanography at UC San Diego cw3e.ucsd.edu
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CW3E Scripps @cw3escripps.bsky.social · Nov 22
Hi there 👋 we're the Center for Western Weather and Water Extremes (CW3E) of @scrippsocean.bsky.social at @ucsandiego.bsky.social

We'll be posting our latest AR Outlooks, news items, and updates on our research into atmospheric rivers and precip extremes. For more info visit: cw3e.ucsd.edu
cw3escripps.bsky.social
We've posted a quick summary of the two storm systems that resulted in multi-day precipitation events over the Southwestern US between 16-19 Nov & 20-23 Nov. Read more here: cw3e.ucsd.edu/wp-content/u...
November 25, 2025 at 11:49 PM
cw3escripps.bsky.social
CW3E AR Update: Multiple weak #AtmosphericRivers and a low-pressure system are forecast to bring precipitation to the Pacific Northwest this week.

See our latest Quick Look 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: GFS integrated vapor transport (IVT; shading and vectors) and sea-level pressure (SLP; contours) forecasts valid at 10 AM PST Tue 25 Nov, 4 AM PST Wed Nov 26, and 10 PM PST Wed Nov 26. Middle: GFS versus ECMWF IVT and SLP forecasts valid at 10 PM PST Tue 25 Nov. IVT difference (green/blue = ECMWF higher; orange/red = GFS higher) shown on the right. Bottom: GFS versus ECMWF IVT and SLP forecasts valid at 10 PM PST Wed 26 Nov. IVT difference (green/blue = ECMWF higher; orange/red = GFS higher) shown on the right. Page 3 of Quick Look. Top: GEFS and ECMWF 7-day control member AR Scale (shading) and ensemble IVT forecasts at 45.5°N, 124.0°W. Bottom: NWS Weather Prediction Center (WPC) quantitative precipitation forecast (QPF) valid for the 72-hour period ending 4 AM PST Fri 28 Nov and QPF/excessive rainfall outlook (ERO) valid for the 24-hour period ending 4 AM PST Thu 27 Nov. Page 4 of Quick Look. Top: Deterministic and ensemble 10-day mean areal precipitation forecasts for the Duwamish watershed. Bottom: GEFS 7-day freezing level forecasts and 6-hourly WPC precipitation forecasts (bars) for the Snoqualmie watershed.
November 24, 2025 at 8:53 PM
cw3escripps.bsky.social
We've posted a quick summary of the strong #AtmosphericRiver that produced heavy rainfall, flash flooding, and landslides across California last week. Stay tuned for a more detailed summary that will examine forecast challenges associated with this event.

cw3e.ucsd.edu/wp-content/u...
Left: GEFS maximum observed AR Scale for the 7-day period ending 4 PM PST 16 Nov 2025. Center: GEFS control AR Scale and IVT analyses for the 7-day period ending 4 PM PST 16 Nov at 38.0°N, 123.0°W (top) and 33.0°N, 117.5°W (bottom). Right: NWS Stage IV quantitative precipitation estimate (QPE) for the 96-hour period ending 4 AM PST 16 Nov 2025.
November 19, 2025 at 10:32 PM
cw3escripps.bsky.social
CW3E Publication Notice: "Subseasonal-to-Seasonal Prediction: The Gap Between Weather and Climate Forecasting (2nd Edition)." Read more about this book, including a subsection on Subseasonal and Seasonal predictability of atmospheric rivers led by CW3E Researchers: cw3e.ucsd.edu/cw3e-publica...
November 19, 2025 at 8:54 PM
cw3escripps.bsky.social
A cutoff low and #AtmosphericRiver drive two separate precipitation events forecast to impact the US West Coast through this Mon 24 Nov.

Read the latest quick look for more details: cw3e.ucsd.edu/wp-content/u...
Page one of the quick look featuring forecast highlights. Page two of the quick look. On top are select model outputs showing the forecast progression of the cutoff low along the California coast. In the middle is the Weather Prediction Center precipitation forecasts for the cutoff. On bottom is a model forecast of Integrated Vapor Transport showing the AR impacting the PNW and the WPC forecast precipitation for this event. Page three of the quick look. Shown are AR Scale forecasts from the GEFS (top) and EPS (bottom) highlighting the uncertainty in the forecast of the AR.
November 19, 2025 at 8:02 PM
cw3escripps.bsky.social
The #AtmosphericRiver that drove heavy precipitation across CA is forecast to bring heavy precipitation and potential flash flooding to Southern CA through Sat 15 Nov.

Check out the forecast details in our latest AR Quick Look: cw3e.ucsd.edu/wp-content/u...
Page one of the quick look featuring forecast highlights. Page two of the quick look. On top are select GFS model time steps showing the propagation of the storm through Saturday. On bottom is a select AR Scale matrix created by CW3E showing the potential for stronger IVT later in the period over Southern CA. Page three of the quick look. On top are precipitation forecasts from the NWS Weather Prediction Center. On the left are QPF and EROs for the 24 hour periods on days 1 and 2 and on the right are the combined 48 hour total for the period. On bottom is a stream gauge forecast along the San Diego River exceeding Action Stage. Page four of the quick look. On top are WPC precipitation forecasts for days 3 and 4 and on the right a select model timestep for the GFS on Monday covering the next precipitation event. On bottom are snowfall forecasts through early Monday on the left and the Winter Storm Severity Index for a portion of the southwest through early Monday.
November 14, 2025 at 9:20 PM
cw3escripps.bsky.social
An impactful #AtmosphericRiver is forecast to make landfall over CA this evening and bring multiple days of heavy precipitation to the state through Sat. Forecasts have trended towards a slower AR, prolonging the event duration & increasing precip. totals. Read more cw3e.ucsd.edu/cw3e-ar-upda...
November 12, 2025 at 11:23 PM
cw3escripps.bsky.social
An #AtmosphericRiver is forecast to bring heavy rain and mountain snow to California this week. The NWS Weather Prediction Center has issued a marginal risk of excessive rainfall for much of coastal California.

See our latest AR Outlook for more information: cw3e.ucsd.edu/cw3e-ar-upda....
November 10, 2025 at 9:51 PM
cw3escripps.bsky.social
CW3E AR Update: Model guidance is showing the potential for #AtmosphericRiver activity along the US West Coast and heavy precipitation over California next week.

See forecast details here: cw3e.ucsd.edu/wp-content/u...
Page one of the quick look featuring forecast highlights. Page two of the quick look. On top are select model images showing the development of the cut-off and the moisture feeding the system. IN the middle is a IVT forecast comparison between the GFS (left) and ECMWF (middle) and the difference between the two (right). On the bottom is showing the difference in the GEFS members and GFS deterministic landfall timing of the AR. Page three of the quick look. On top is CW3E's landfall tool showing the difference in forecast probability of IVT > 250 kg m-1 s-1 in the EPS and GEFS for the next 15 days. On bottom is a select AR Scale matrix based on the GEFS forecast for a location in Northern California. Page four of the quick look. On top is CW3E's watershed precipitation tool showing the similarity in the forecast precipitation in the GEFS (left) and EPS (center) over the next 10 days. On bottom is the Climate Prediction Center's Days 8-14 Hazard outlook showing a moderate risk for Heavy Precipitation and Heavy Snow over California next weekend.
November 7, 2025 at 9:42 PM
cw3escripps.bsky.social
CW3E Publication Notice: "Improving Streamflow Simulation through Machine Learning-Powered Data Integration and Its Potential for Forecasting in the Western U.S." in the @egu.eu's Hydrology and Earth System Sciences. Read more about this research here: go.ucsd.edu/4qMBt27
November 7, 2025 at 7:33 PM
cw3escripps.bsky.social
CW3E AR Update: A pair of #AtmosphericRivers are forecast to impact the US West Coast the next two days. These AR are forecast to bring precip to the Pacific Northwest and Northern CA and snowfall to the Northern Cascades.

See forecast details here: cw3e.ucsd.edu/wp-content/u...
Page one of the quick look featuring forecast highlights Page two of the quick look. On top are select times of forecast Integrated Vapor Transport (IVT) from the GFS showing the propagation the two ARs in the next two days. On bottom are two observed and forecast IVT and AR Scale for coastal points in Northern California (left) and Washington (right) Page three of the quick look. On top is observed and forecast IVT and AR Scale for coastal point in Oregon. On bottom is Weather Prediction Center forecast precipitation for days 1 and 2 on the left and the 48 hour total precipitation on the right. Page four of the quick look. On top are forecast snowfall through Friday and GEFS forecast freezing levels for a watershed in Northern Washington. On bottom are streamflow forecasts with a gauge in Northwest Washington from the NWRFC on the left and a gauge in Northern California on the right.
November 5, 2025 at 8:29 PM
cw3escripps.bsky.social
CW3E AR Update: Back-to-back atmospheric rivers are forecast to bring precipitation and coastal impacts to the Pacific Northwest and N. California through this week, with more AR activity this weekend. Read our latest Quick Look here: cw3e.ucsd.edu/wp-content/u...
November 4, 2025 at 10:14 PM
cw3escripps.bsky.social
CW3E AR Update: An active weather pattern will continue this week, with multiple #AtmosphericRivers forecast to bring heavy precipitation to portions of the Pacific Northwest and northern California.

See our latest AR Outlook for more details: cw3e.ucsd.edu/cw3e-ar-upda....
November 3, 2025 at 10:02 PM
cw3escripps.bsky.social
CW3E Quick Summary:

An atmospheric river (AR) made landfall early Fri 31 Oct, bringing AR3 conditions the Pacific Northwest. The AR produced 5-8" of precipitation over the region during the 48-hour period ending at 5 am PDT Sun 02 Nov.

See the Quick Summary for more info:
go.ucsd.edu/3WBUx5i
November 3, 2025 at 6:20 PM
cw3escripps.bsky.social
CW3E AR Update: Multiple #AtmosphericRivers are forecast to impact the US West Coast and potentially bring heavy precipitation to portions of Washington, Oregon, and California over the next 7 days.

See our latest AR Outlook for more information: cw3e.ucsd.edu/cw3e-ar-upda....
October 30, 2025 at 9:00 PM
cw3escripps.bsky.social
Earlier this month, CW3E met with Colorado partners and stakeholders to celebrate the installation of a new hydrometeorological station at Colorado Mountain College. This is the 7th station in the Yampa Basin Atmosphere and Soil Moisture Integrated Network (Y-BASIN).

cw3e.ucsd.edu/ribbon-cutti...
(Left) Ribbon-cutting ceremony at the new Colorado Mountain College (CMC) Y-BASIN station. Photo credit: Scott Kimmey (CMC). (Right) CW3E staff and a local volunteer working on CMC Y-BASIN station install. Photo credit: Nathan Stewart (CMC).
October 29, 2025 at 7:27 PM
cw3escripps.bsky.social
CW3E AR Update: Pair of #AtmosphericRivers , one landfalling today and a second forecast early next week, are forecast to bring precipitation to the Pacific Northwest and Northern California.

Check out our latest AR Outlook for more information: cw3e.ucsd.edu/cw3e-ar-upda...
October 24, 2025 at 9:22 PM
Reposted by CW3E Scripps
scrippsocean.bsky.social
🌧️ Better #AtmosphericRiver forecasts 🤝🏽 smarter water storage

Lake Mendocino just became the first U.S. reservoir approved to use forecast-informed operations — a strategy pioneered by @cw3escripps.bsky.social Director Marty Ralph and partners to boost water supply while managing flood risk.
This Northern California reservoir has pioneered a way to store more water
After years of advocacy and experimentation, officials will celebrate the reservoir’s status as the nation’s first to get the go-ahead to adopt a flexible, forecast-based operations policy.
www.sfchronicle.com
October 22, 2025 at 7:38 PM
cw3escripps.bsky.social
CW3E AR Update: #AtmosphericRivers forecast to bring precipitation to the Pacific Northwest and Northern California later this week. Read more in our latest AR Outlook here: cw3e.ucsd.edu/cw3e-ar-upda...
October 22, 2025 at 9:44 PM
cw3escripps.bsky.social
CW3E AR Update: Multiple #AtmosphericRivers are forecast to impact the US West Coast later this week, with unsettled weather potentially continuing through next week.

See our latest AR Outlook for more details: cw3e.ucsd.edu/cw3e-ar-upda....
October 20, 2025 at 10:44 PM
cw3escripps.bsky.social
A strong upper-level trough and associated cutoff low moved southward along the California coast between 13-14 October 2025, bringing heavy rain, mountain snow, and severe weather to portions of Central and Southern California.

See our latest Quick Summary for more information: go.ucsd.edu/4qhoTYg
October 17, 2025 at 7:08 PM
cw3escripps.bsky.social
Moisture associated with Tropical Storms Priscilla and Raymond fueled multiple episodes of heavy rainfall over the Colorado River Basin between Thu 9 Oct and Tue 14 Oct.

See our latest Quick Summary for more information: cw3e.ucsd.edu/wp-content/u....
Left: National Weather Service (NWS) Stage IV quantitative precipitation estimate (QPE) for the 5-day period ending at 5 am PDT Tue 14 Oct. Right: Local storm reports received by the NWS during 9-14 Oct. Color denotes category of storm report.
October 16, 2025 at 9:30 PM
cw3escripps.bsky.social
CW3E AR Update: A moderate-to-strong atmospheric river is forecast to move onshore over the Pacific Northwest on Saturday, although there is still some uncertainty as to the timing, intensity, and potential impacts to the region. Read more in our latest Quick Look: cw3e.ucsd.edu/wp-content/u...
October 15, 2025 at 7:58 PM
cw3escripps.bsky.social
CW3E AR Update: A cutoff low and an #AtmosphericRiver will bring primarily beneficial early-season precipitation to California and help reduce wildfire risk over southern California.

See our latest Quick Look for more information: cw3e.ucsd.edu/wp-content/u....
(Left) GFS integrated vapor transport (IVT; shading and vectors) and sea-level pressure (SLP; contours) forecast valid at 8 AM PDT Tue 14 Oct. (Right) NWS Weather Prediction Center (WPC) quantitative precipitation forecast (QPF) and excessive rainfall outlook (ERO) valid for the 24-hour periods ending at 5 AM PDT Tue 14 Oct and 5 AM PDT Wed 15 Oct.
October 13, 2025 at 7:45 PM
cw3escripps.bsky.social
CW3E Precipitation Update: Multiple Precipitation Events to Impact the Western US Through Early Next Week. Read more in our latest outlook here: cw3e.ucsd.edu/cw3e-precipi...
October 9, 2025 at 11:20 PM