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CW3E Scripps
@cw3escripps.bsky.social
700 followers 3 following 110 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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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
While our team was busy preparing this outlook, we also posted a brief summary of the three ARs that brought heavy precipitation to portions of Washington, Oregon, and northern California last week.

cw3e.ucsd.edu/wp-content/u...
Left: GEFS maximum observed AR Scale for the 7-day period ending 4 AM PST 7 Nov 2025. Center: GEFS control AR Scale and IVT analyses for the 7-day period ending 4 AM PST 7 Nov at 43.0°N, 124.5°W (top) and 39.0°N, 123.5°W (bottom). Right: NWS Stage IV quantitative precipitation estimate (QPE) for the 96-hour period ending 4 AM PST 7 Nov 2025.
November 11, 2025 at 4:10 AM
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
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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
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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
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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
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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
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
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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
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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
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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
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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
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CW3E Publication Notice: "Comparison of GOES-17 Atmospheric Motion Vectors With AR Recon Dropsonde Data and Assessment of Wind Fields in the Global Forecast System During Atmospheric River Events" in the @agu.org's Journal of Geophysical Research: Atmospheres. Read more here: go.ucsd.edu/3L1zPsQ
October 9, 2025 at 4:08 PM
cw3escripps.bsky.social
A predecessor rain event associated with the moisture from Hurricane Priscilla is forecast to bring rainfall to Arizona and New Mexico Thu-Sat, followed by additional precipitation associated with an upper-level trough, which may continue into early next week. Read more here: go.ucsd.edu/4q0WYM9
October 7, 2025 at 7:54 PM
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CW3E Publication Notice: "Leveraging the Atmospheric River Framework to Categorize Top-Decile Precipitation Regimes in Colorado" in @agu.org 's Geophysical Research Letters. Read more about this research: cw3e.ucsd.edu/cw3e-publica...
October 6, 2025 at 9:05 PM
cw3escripps.bsky.social
Multiple #AtmosphericRivers and a complex storm system brought several rounds of precipitation to the western US over the past week.

For a brief synopsis of these weather events, visit: cw3e.ucsd.edu/wp-content/u....
National Weather Service (NWS) Stage IV quantitative precipitation estimate (QPE) for the 48-hour period ending 5 AM PDT 30 Sep 2025 (left) and the 96-hour period ending 5 AM PDT 4 Oct 2025 (right).
October 4, 2025 at 7:02 PM
cw3escripps.bsky.social
A trough and remnant moisture from the atmospheric river (AR) that made landfall over the Pacific Northwest on Tuesday drives precipitation over the Sierra Nevada, Great Basin and, Southern Idaho today into tomorrow.
Check out our latest Quick Look for more information: 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 images of IVT from the Global Forecast System (GFS) showing the propagation of the IVT driving the system. On bottom is CW3E's Landfall Tool showing the percentage of members from the GEFS that have IVT > 150 kg m-1 s-2 along the US West Coast in the next 16 days. Page three of the quick look. On top are 24-hour forecasts from the Weather Prediction Center for periods ending at 5 AM on 3 (left) and 4 (right) October. The bottom left image is the percentage of water year normal precipitation accumulation based on the National Blend of Models 7-day precipitation. The bottom right image shows the drought conditions for the Western US from the Drought Monitor.
October 2, 2025 at 8:40 PM
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CW3E Publication Notice: "Observing atmospheric rivers using multi-GNSS airborne radio occultation: system description and data evaluation" in @egu.eu's Atmospheric Measurement Techniques.

For a summary of this paper, visit: cw3e.ucsd.edu/cw3e-publica....
Figure 5 from Cao et al. (2025). Overview of IOP04 (4 Feb 2020): flight track (thin black line), dropsonde releases (black circles), and setting/rising ARO tangent-point paths (solid/dashed blue lines) over integrated vapor transport (IVT), with symbols marking lowest-altitude class and short segments indicating the ray-path portion contributing 50% of excess phase.
October 2, 2025 at 3:32 AM