CW3E Scripps
LightNews LightNews
banner
cw3escripps.bsky.social
CW3E Scripps
@cw3escripps.bsky.social
770 followers 3 following 150 posts
The Center for Western Weather and Water Extremes of Scripps Institution of Oceanography at UC San Diego cw3e.ucsd.edu
Posts Replies Media Videos
Pinned
cw3escripps.bsky.social
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
CW3E AR Update: An #AtmosphericRiver is forecast to bring moderate precipitation to the Pacific Northwest this weekend into early next week.

See 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 GFS IVT forecasts showing the propagation of the AR this weekend. In the middle is a comparison between the GFS and EC IVT late in the event. On the bottom is a comparison between the EPS and GEFS AR Scale for a point in the central Oregon coast. Page three of the quick look. On top is WPC 72-hour forecast precipitation on the left and the marginal excessive rainfall outlook issued over the Olympic Peninsula on the right. On bottom are freezing level forecasts watersheds in the Washington and Oregon Cascades. Page four of the quick look. Shown are NWRFC streamflow forecasts across western Washington.
February 5, 2026 at 10:24 PM
cw3escripps.bsky.social
The forecast for Super Bowl Sunday near Levi's Stadium is mostly dry and warm, with a slight chance of light rain in the evening. Normally, December, January and February are the three wettest months of the year in northern California, but it has been unusually dry since early January.
February 5, 2026 at 1:57 AM
cw3escripps.bsky.social
A family of #AtmosphericRivers brought moderate-to-heavy precipitation to portions of Washington last week.

See our latest Quick Summary for more information: cw3e.ucsd.edu/wp-content/u....
Left: GEFS maximum observed coastal AR Scale for the 7-day period ending 4 PM PST 1 Feb 2026. Center: GEFS control AR Scale and IVT analyses for the 7-day period ending 4 PM PST 1 Feb 2026 at 47.5°N, 124.5°W. Right: NWS Stage IV total estimated precipitation for the 6-day period ending 4 AM PST 2 Feb 2026.
February 3, 2026 at 9:00 PM
cw3escripps.bsky.social
CW3E AR Update: Multiple #AtmosphericRivers are forecast to bring heavy precipitation to portions of 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. GFS integrated vapor transport (IVT; shading and vectors) and sea-level pressure (SLP; contours) forecasts valid at 10 AM PST Tue 27 Jan (top left), 10 AM PST Wed 28 Jan (top right), 4 PM PST Thu 29 Jan (bottom left), and 4 PM PST Sat 31 Jan (bottom right). 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 4 AM PST Mon 26 Jan through 4 AM PST Wed 11 Feb. (Bottom) GEFS 7-day control and ensemble AR Scale and IVT forecasts for 47°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 4 AM PST Thu 29 Jan, Fri 30 Jan, and Sat 31 Jan. Bottom left: WPC Total quantitative precipitation forecast (QPF) valid for the 7-day period ending 4 AM PST Mon 2 Feb. Bottom right: GEFS ensemble freezing level and WPC 6-hourly QPF forecasts in the Duwamish watershed for the 7-day period ending 4 AM PST Mon 2 Feb.
January 26, 2026 at 10:28 PM
cw3escripps.bsky.social
CW3E has prepared a detailed event summary discussing the multiple #AtmosphericRivers that produced heavy precipitation, significant snowfall, and widespread impacts over the US West Coast between 18–27 Dec 2025. Read our extensive analysis here: cw3e.ucsd.edu/cw3e-event-s...
January 13, 2026 at 9:27 PM
cw3escripps.bsky.social
We posted a quick summary of the #AtmosphericRivers that influenced precipitation across the US West Coast and led to heavy precipitation in CA this past week. Check out more here: cw3e.ucsd.edu/wp-content/u...
January 6, 2026 at 10:19 PM
cw3escripps.bsky.social
Multiple systems are forecast to bring low-elevation rain and heavy mountain snow 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 left: GFS integrated vapor transport (IVT; shading and vectors) and sea-level pressure (SLP; contours) forecasts valid at 10 AM PST Tue 6 Jan. Top right: GFS freezing level (shading), SLP (contours), and 10-meter wind (barbs) forecasts valid at 10 AM PST Tue 6 Jan. Bottom left: GFS IVT (shading and vectors) and SLP (contours) forecasts valid at 7 AM PST Wed 7 Jan. Bottom right: GFS 500-hPa geopotential height (contours), absolute vorticity (shading), and wind (barbs) forecasts valid at 7 AM PST Wed 7 Jan. Page 3 of Quick Look. Top: GEFS 7-day freezing level forecasts and 6-hourly WPC precipitation forecasts for the Skykomish watershed. Color shading denotes portion of precipitation forecast to fall as rain, snow, or uncertain precipitation type. Bottom left: NWS Weather Prediction Center (WPC) quantitative precipitation forecast (QPF) valid for the 72-hour period ending 4 AM PST Fri 9 Jan. Bottom right: NWS snowfall accumulation forecast for the 72-hour period ending 4 AM PST Thu 8 Jan. Page 4 of Quick Look. Top left: West-WRF ensemble cumulative snowfall forecasts at Snoqualmie Pass for the 7-day period ending 4 PM PST Sun 11 Jan. Top right: NWS Weather Prediction Center (WPC) Winter Storm Severity Index valid through 7 AM PST Thu 8 Jan. Bottom: NRCS basin (HUC6 boundaries) and station (dots) snow water equivalent (SWE) expressed as a percent of the 1991-2020 median as of 5 Jan.
January 5, 2026 at 10:08 PM
cw3escripps.bsky.social
Check out our latest AR Quick Look discussing the #AtmosphericRiver forecast to make landfall later today and bring precipitation impacts to California into early next week. Read more here: cw3e.ucsd.edu/wp-content/u...
January 2, 2026 at 8:56 PM
cw3escripps.bsky.social
A pair of #AtmosphericRivers and a low-pressure system drive precipitation across California over the next week, including potentially significant snowfall over the Sierra Nevada during the second AR.

See the latest AR outlook for further details: cw3e.ucsd.edu/cw3e-ar-upda...
December 30, 2025 at 10:19 PM
cw3escripps.bsky.social
CW3E Publication Notice: "Compound Atmospheric Drivers of the Catastrophic 2025 Los Angeles Urban Firestorm" in @nature.com's npj Natural Hazards.

For a summary of this paper, visit: cw3e.ucsd.edu/cw3e-publica....
Atmospheric drivers of the January 2025 Los Angeles firestorm. (a-c) An amplified upper-level ridge and retrograding trough produced a highly meridional jet and strong northerly flow over Southern California at 500-250 hPa. (d-e) Subsidence and mountain-wave activity further intensified surface winds and impeded aerial fire suppression. (f) A wind-rose comparison shows that the 2025 event (Firestorm’25) exhibited a distinct northerly “jet-forced Santa Ana” signature that differs from typical historical Santa Ana wind events, but is similar to a previous high-impact Santa Ana windstorm on December 1, 2011 (Windstorm’11).
December 30, 2025 at 1:38 AM
cw3escripps.bsky.social
Multiple storms are forecast to bring moderate-to-heavy precipitation to California later 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. Left column: GFS 500-hPa geopotential height (contours), absolute vorticity (shading), and wind (barbs) forecasts valid at 4 AM PST Wed 31 Dec (top row), 10 AM PST Thu 1 Jan (middle row), and 10 AM PST Fri 2 Jan (bottom row). Center column: GFS integrated water vapor (IWV; shading), sea-level pressure (SLP; contours), and 850-hPa wind (barbs) forecasts valid at 4 AM PST Wed 31 Dec (top row), 10 AM PST Thu 1 Jan (middle row), and 10 AM PST Fri 2 Jan (bottom row). Right column: GFS integrated vapor transport (IVT; shading and vectors) and sea-level pressure (SLP; contours) forecasts valid at 4 AM PST Wed 31 Dec (top row), 10 AM PST Thu 1 Jan (middle row), and 10 AM PST Fri 2 Jan (bottom row). Page 3 of Quick Look. Top: GEFS 16-day probability of AR conditions [IVT ≥250 kg/(ms)] along the US West Coast. Bottom: GEFS and 7-day control member AR Scale (shading) and ensemble IVT forecasts at 33.0°N, 117.5°W and 38.0°N, 123.0°W. Page 4 of Quick Look. Top: NWS Weather Prediction Center (WPC) excessive rainfall outlooks (EROs) valid for the 24-hour periods ending 4 AM PST Thu 1 Jan, Fri 2 Jan, and Sat 3 Jan, and total quantitative precipitation forecast (QPF) valid for the 72-hour period ending 4 AM PST Sat 3 Jan. Bottom: Deterministic and ensemble 10-day mean areal precipitation forecasts for the Los Angeles watershed.
December 29, 2025 at 10:35 PM
cw3escripps.bsky.social
A pair of #AtmosphericRivers are forecast to bring heavy precipitation and snowfall to California with the risk for flooding in southern California in the next five days.

See more here: cw3e.ucsd.edu/wp-content/u...
Page one of the quick look featuring featuring forecast highlights. Page two of the quick look. On top are select IVT model outputs from CW3E's West-WRF based on the GFS showing the two ARs. On bottom are west-wrf ensemble AR Scale matrices for a location near the Bay Area and in Coastal Southern CA. Page three of the quick look. On top is the NBM 5-day precipitation forecast on the left and a select model output from the West_WRF showing simulated reflectivity indicating an NCFR along southern California. On the bottom are watershed precipitation forecasts from CW3E's watershed precipitation tool for the Seven Oaks Dam catchment and the Castaic Lake catchment. Page four of the quick look. On top are Excessive Rainfall outlooks issued by the WPC and a HEFS stream level forecast for a gauge along the Ventura River within the moderate risk EROs shown on the left. On bottom are freezing level forecasts for the GEFS showing a decline throughout the ARs and on the left is forecast snowfall from the NWS showing heavy snowfall across the Sierra Nevada.
December 23, 2025 at 9:30 PM
cw3escripps.bsky.social
CW3E has prepared a detailed summary of the long-duration #AtmosphericRiver that produced extreme precipitation and caused record-breaking flooding in Washington earlier this month.

cw3e.ucsd.edu/cw3e-event-s...
Top left: GEFS maximum AR Scale during the 7-day period ending 4 AM PST 12 Dec 2025. Top center: GEFS control AR Scale and IVT analyses for the 7-day period ending 4 PM PST 12 Dec 2025 at 47.0°N, 124.0°W. Top right: AR Scale matrix showing maximum IVT magnitude and duration of periods with AR conditions during the 7-day period ending 4 PM PST 12 Dec 2025 at 47.0°N, 124.0°W. Bottom left: NWS Stage IV quantitative precipitation estimate (QPE) for the 96-hour period ending 4 AM PST 12 Dec 2025. Bottom center: Maximum observed flood stage at stream gages that reached at least minor flood stage during 8-13 Dec 2025. Bottom right: Photo of damage to US 2 near Stevens Pass (credit: Washington State DOT).
December 23, 2025 at 9:24 PM
cw3escripps.bsky.social
Multiple #AtmosphericRivers and low-pressure systems will bring heavy precipitation to much of California this week. A high risk of excessive rainfall has been issued for the Transverse Ranges Wed into early Thu.

See our latest AR outlook for more details: cw3e.ucsd.edu/cw3e-ar-upda....
December 22, 2025 at 11:01 PM
cw3escripps.bsky.social
An active weather pattern is forecast to set up with multiple #atmosphericrivers over California this weekend into next week. Significant rainfall totals are forecast over the region, with flooding possible. Read our latest update here: go.ucsd.edu/4sbMCKE & Pay attention to @nws.noaa.gov forecasts.
December 19, 2025 at 11:01 PM
cw3escripps.bsky.social
Press Release: "Atmospheric River Research Flights Go Global"

Read the latest @scrippsocean.bsky.social news article to learn about the expansion of #AtmosphericRiver Reconnaissance flights across the Pacific and Atlantic basins here: scripps.ucsd.edu/news/atmosph....
Atmospheric River Research Flights Go Global
Inside the cockpit of a NOAA Gulfstream IV during an atmospheric river mission in February 2025. Image credit: Erik Jepsen/UC San Diego.
scripps.ucsd.edu
December 18, 2025 at 12:44 AM
cw3escripps.bsky.social
An #AtmosphericRiver is forecast to move over the Pacific Northwest on Thu., bringing additional rainfall to WA, OR, and Northern CA as it shifts down the coast thru Fri. A second AR will follow behind on Sat. with additional impacts forecast over Northern CA thru Mon. Read more: go.ucsd.edu/451WXPa
December 17, 2025 at 11:20 PM
cw3escripps.bsky.social
CW3E AR Update: AR activity is forecast to continue over the PNW thru early Wed., with a 2nd AR forecast to move onshore late on Wed. over the PNW and N. CA, through Fri. Models are also highlighting the potential for AR activity over CA next week. Read more here: cw3e.ucsd.edu/cw3e-ar-upda...
December 15, 2025 at 10:42 PM
Reposted by CW3E Scripps
scrippsocean.bsky.social
🏅Congratulations to the 3️⃣ scientists at Scripps Oceanography who will be honored by @agu.org at this week's AGU Annual Meeting through its Honors and Recognition program, which acknowledges section awardees, named lecturers & elected fellows! Learn more: scripps.ucsd.edu/news/three-s...
December 15, 2025 at 7:54 PM
cw3escripps.bsky.social
CW3E Publication Notice: "The NCEI Historical Data Record for Atmospheric Rivers: Visualization over the Western United States" in the @ametsoc.org Bulletin of the American Meteorological Society. Read more here: cw3e.ucsd.edu/cw3e-publica...
December 15, 2025 at 5:52 PM
cw3escripps.bsky.social
Another strong #atmosphericriver is forecast to move onshore over British Columbia & the Pacific Northwest on Sun 14 Dec, shifting southward along the US West Coast and into N. California during the beginning of next week. Read more here in our latest AR Outlook: cw3e.ucsd.edu/cw3e-ar-upda...
December 12, 2025 at 10:54 PM
cw3escripps.bsky.social
CW3E Publication Notice: "Insights from a 25-year Database of Post-Fire Debris Flows in California" published in the International Journal of Wildland Fire with collaborators @cageosurvey.bsky.social Read more about this research here: cw3e.ucsd.edu/cw3e-publica...
December 11, 2025 at 3:54 AM
Reposted by CW3E Scripps
scrippsocean.bsky.social
🌧️ How do we study #AtmosphericRivers? 🛫 By flying planes into them, obviously! @cw3escripps.bsky.social's Alex Tardy caught up with Fox Weather to share why flights are critical for understanding ARs ahead of a powerful atmospheric river headed for the Northwest. U.S. ⬇️
Powerful atmospheric river headed for the Northwest U.S. | Latest Weather Clips | FOX Weather
Project Policy Analyst and Meteorologist with the Center for Western Weather and Water Extremes at UC San Diego’s Scripps Institution of Oceanography, Alex Tar
www.foxweather.com
December 11, 2025 at 12:23 AM
cw3escripps.bsky.social
The atmospheric river (AR) presently impacting the Pacific Northwest will continue to produce very heavy precipitation in western Washington today into early tomorrow, leading to potentially historic riverine flooding.

Read more 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 two select model images showing the slightly northerly shift in the AR. On bottom are 48-hr WPC forecasts showing the same northerly shift in the precipitation. Page three of the quick look. On top are GEFS freezing level forecasts for the Snoqualmie Watershed in the Washington Cascades showing the high forecast freezing levels with this system. On bottom are NWRFC stream level forecasts showing the high number of gauges exceeding flood stage. Page four of the quick look. On top is West-WRF precipitation forecasts in the vicinity of the historic riverine flooding. On bottom are key messages from the NWS regarding this event.
December 10, 2025 at 6:24 PM
cw3escripps.bsky.social
We posted a quick summary of the #AtmosphericRiver the brought precipitation to the Pacific Northwest on Dec 3-6 ahead of the system presently impacting the region. Read more here: cw3e.ucsd.edu/wp-content/u...
December 9, 2025 at 10:06 PM