Discover and read the best of Twitter Threads about #CAWater

Most recents (24)

HAPPENING NOW! Join us as we explore the soil-water nexus and what it means for California's climate goals Image
Dr. Sarah Castle welcomes everyone and gives a little more information about @SusCon_CA & our BRAND NEW soil health program

Thanks to our amazing sponsors @esassoc @Holland_Knight @IronHorseVyds & @SpottswoodeWine!
If you missed our first #webinar in our soils series, you can watch it right here
Read 38 tweets
We accumulated 3.5" (9 cm) of #snow over the last 24 hours and it is expected to continue over the next couple days.

We've talked about snowfall totals and this year's move to second place, which is fantastic, but what about the water content of our snowpack? 🧵

#CAwx #CAwater
Above is a plot of Snow Water Equivalent (SWE; the amount of water that can come from melting the snowpack) from the @USDA_NRCS SNOTEL site at the Snow Lab. We can see that 2022/2023 currently has the highest SWE of any year back to 1984 for this date (69"; 175 cm). 🧵
However, 2010/2011 has the record for the greatest maximum SWE overall at 72.3" (184 cm). At the CSSL, our peak SWE generally occurs on March 24th and that is rapidly approaching. Given the short-term forecast, it's possible that we may fall behind 2010/2011 again. 🧵
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Brief thoughts on likely return to active weather pattern in CA after a much-needed several day break right now. There is *high* confidence that wet and cool conditions will return next week, but right now there is *low* confidence in strength of storms. #CAwx #CAwater (1/4) Time series plot from ECMWF...
Ensembles suggest that there is very high likelihood that unsettled and occasionally stormy conditions return to most of CA by early next wk. But vast majority of ensemble members suggest this will involve series of weak to moderate systems vs. major storms. #CAwx #CAwater (2/4)
Also, for the moment, it looks like these are more likely to be colder (snow-accumulating) storms once again, with less runoff than recent events. So this pattern might actually stave off substantial snowpack melting yet further-at least into April. #CAwx #CAwater (3/4)
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I have never seen this type of #flood control measure before! Here is how some farmers deal with a breach in the Tulare Lake bottom. I assume they will pile some additional dirt on. #cawater #cawx #farm #agriculture
Here is the problem they were facing - Image
For all of those haters and doubters - here is what it looks like now - trees protected as well as community nearby. #cawater #flood #cawx #desperatemeasures #agriculture Image
Read 4 tweets
Brief thread about...snow. As of this weekend, the Southern Sierra now appears to have largest snowpack in recorded history (as measured by snow water equivalent, or SWE). Not just for the calendar date, but for *any* date! #CAwx #CAwater [1/n] SWE time series trace from DWR for the major California Sier
As I earlier noted was plausible, the "warm" atmospheric river storm on Fri actually *increased* net watershed SWE substantially--partly because it still snowed at high elevations, but also because lower elevation snowpack absorbed a lot of rainwater! #CAwx #CAwater [2/n]
This map plot of the SWE change over the past 24 hours really tells the tale--much snow melting and SWE losses below about 4.5k ft in elevation but large *gains* above that level. Classic "warm-ish" storm dipole pattern! #CAwx #CAwater [3/n] 24 hr SWE change map for California. It depicts SWE loss at
Read 8 tweets
A few storm updates following my session Wed PM:
Event still largely on track, but two modest shifts that could affect impacts:
1) Storm may not be quite as warm across central & northern Sierra; could see some very heavy snowfalls above 6,500 ft once again.
#CAwx #CAwater [1/5]
2) Rainfall may be a bit heavier and more concentrated across the northern portion of central CA (but slightly less to north). This means flood risk in Monterey County (including Big Sur Coast), as well as southern Sierra & foothills, has increased somewhat. #CAwx [2/5]
3) Still not expecting widespread major river flooding. HOWEVER, localized significant flooding of creeks & streams is likely, and *possibly* on a few smaller rivers in the above-mentioned areas, due to combo of heavy rain & snowmelt below ~4,500ft elev. #CAwx [3/5]
Read 5 tweets
The #snow over the weekend brought our total to 48.33 feet for the year, which is 0.56 feet above the 2016/2017 total of 47.77 feet. But, 2017 still has an advantage compared to this season: Snow Water Equivalent (SWE; water that comes from melting snow). 🧵

#CAwx #CAwater
Due to our recent light snow, we have had less SWE accumulation than in the 2016/2017 winter, which means that we have less water available in the snowpack for use as it melts. In fact, we had 20% more SWE to this point in the season in 2017 (2017 - 65.3", 2023 - 54.4").
With more storms on the horizon, it's likely that we'll make up for this discrepancy and we may end up near or above the 2017 SWE max by the end of the season. Only time will tell though.
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First cloud-free #Sentinel2 satellite images in a month dropped yesterday. Great to check out snow levels, reservoirs, and wet wet wet in the Butte Basin/Lower Sacramento River. First image compares Colusa area now vs 12/15/2022. #Geography #RemoteSensing #CaWx #CaStorm 1/x
Imagery paints a picture of soil types. Along the River, coarser soils settle quickly once floodwaters slow down. Blue areas have more clay, because super-fine soil particles can stay suspended longer, travel farther in slow-moving floodwaters. Orchards prefer coarse soils. 2/x
Plumes of sediment from the Pajaro and Salinas Rivers are still very visible in the Monterey Bay on 1/19/2023. Two visualizations of sediment in the lower Delta and San Pablo Bay. 3/x
Read 6 tweets
TODAY: @CaWaterBoards Voluntary Agreements Science Report Workshop 10:00 a.m.
CalEPA Building 1001 I Street, Sacramento
Watch VA Workshop…
Register for Public Comment
The @CaWaterBoards staff has begun with their presentation on the Proposed #VoluntaryAgreements, including updates to the #BayDeltaPlan.
Currently staff are reviewing the @cawaterboards efforts to date on the #BayDeltaPlan .
Read 163 tweets
For folks emerging from retirement to champion big gulp for Delta tunnel (mostly older white men who ruled over #CAWater for decades) here are facts:

1) Doesn’t protect communities that will experience 100% of loss of life & 80% of economic loss.
2) New intakes are not flood proof or protected from salt water intrusion. Our comments explain this.…
3) Exported water will lead to further groundwater depletion in Sac Valley.
Read 7 tweets
🧵 As much as I've talked about our impressive snowpack in Utah (and it is VERY impressive), the numbers in the Southern Sierra are truly mind-boggling! #cawx #nvwx #cawater
Just look at these basins via NRCS! The southeast Sierra Nevada, flowing into Mono Lake and Owens Valley is at an 8-station average of 452% of median! For this deep into the season, that's crazy!
One site, Big Pine Creek, is at 738% of median and already well over double the median peak that typically occurs in late March.
Read 9 tweets
Additional widespread precipitation is likely over the next 8-9 days over the northern 2/3 of CA, and it will be heavy at times (especially northern third of CA). Strongest storm, with some more heavy rain, wind, and thunderstorms, is due in on Sat. #CAwx #CAwater [1/4] Projected precipitation map from ECMWF ensemble depicting wi
However, these are primarily areas that have not been nearly as wet as central CA recently. Also, these will generally be colder storm systems, bringing a greater balance of snow (vs rain) in mountains & somewhat limiting higher elevation runoff. #CAwx #CAwater [2/4]
For these reasons, although there will be *some* additional flooding, it increasingly look like *most* of CA will probably thread the needle--thereby avoiding a more widespread/severe flood scenario. Massive Sierra snowfalls are possible during this period! #CAwx #CAwater [3/4]
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Okay, folks. Starting to look like it's going to be a rough 10+ days from a flood risk perspective in Northern California, with a series of very wet & high-impact storms. Brief thread now; blog post late this PM; YouTube live Q&A Tue. [1/n] #CAwx #CAwater
The next inbound storm looks like it will be quite strong. A rapidly deepening surface low (i.e., meteorological "bomb cyclone") will remain well offshore, but the associated warm and cold fronts will bring widespread heavy rain and strong winds to NorCal later Wed. #CAwx [2/n] Map showing ECMWF model representation of "bomb cyclone
This storm would be fairly notable in its own right, as it will be associated with an unusually well-defined warm *and* cold frontal passages and an exceptionally moist and relatively warm #AtmosphericRiver. #CAwater #CAwx [3/n] Map depicting ECMWF representation of Wednesday storm, inclu
Read 17 tweets
Some thoughts on impacts from ongoing and likely prolonged very wet spell in NorCal. (Short thread). TL;DR: widespread heavy precipitation is likely, with mostly minor flood issues becoming more widespread this weekend & *possibly* more significant next week. [1/n] #CAwx #CAwater
Lighter precipitation continues today, but the next significant storm will be this weekend. This will come in the form of a moderately strong low pressure system coupled with a robust, warm, and relatively slow-moving atmospheric river. #CAwx #CAwater [2/n] Image
This New Year's storm will bring heavy rainfall to essentially all of NorCal, and widespread precipitation to SoCal as well. This storm will be quite warm, too, with very high freezing levels initially bringing rain even at 7,000 feet. #CAwx #CAwater [3/n] Precipitation map from ECMW...
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Latest seasonal predictions from NMME/IMME ensembles out today. Overall North Pacific pattern still looks very #LaNina-like: unusually wet PacNW and BC; unusually dry in SoCal & Lower Colorado Basin due to persistent NE Pacific ridging. HOWEVER... #WAwx #CAwx #AZwx (1/4) Maps of seasonal prediction...Image
...However, exact position of N. Pac. ridge is key. Too far east, & CA stays dry, but far enough west & Sierra benefits from cold storms diving south. High confidence in winter ridge, but CA will be on razor's edge--exact position will dictate dry vs wet overall. (2/4)#CAwx
This is why seasonal prediction is hard. It's quite likely models are correct about strong, anomalous North Pacific ridge signal (mainly due to #LaNina). But that doesn't directly translate to CA precip--it only offers a modest tilt in odds toward dry winter. #CAwx #CAwater (3/4)
Read 6 tweets
Some mixed news on CA weather front over next couple of weeks. First, by Monday, another "inside slider" system will bring another burst of cooler & winder conditions statewide. Once again, some Sierra snow showers are possible, but most places stay dry. #CAwx #CAwater
Midweek, however, an even colder airmass and associated low pressure center will slide down the coast slightly farther to the west. This system, although still quite dry, stands a better chance of bringing convective activity (scattered showers/isolated thunder) statewide. #CAWx
The biggest impact from this mid-week system, outside of some additional modest Sierra snow accumulations and a few pockets of accumulating small hail showers at lower elevations (like last week in SoCal), will be a dramatic shift toward much colder temperatures. #CAwx
Read 6 tweets
October and December were extremely wet in parts of California (record wet in some parts of NorCal). But the most recent ~45 day stretch (Jan 1-Feb 17) has been among driest mid-winter periods on record most of CA, NV, UT, and portions of adjacent states. #CAwx #CAwater (1/3) Image
This has yielded in a seasonal "percent of average" precipitation map that is pretty misleading. Most of CA has slipped slightly below avg precip for the season to date--except for narrow swath along I-80 corridor that experienced the extreme Oct #AtmosphericRiver. #CAwx (2/3) Image
Yet hydrologic/landscape conditions--inc. surface reservoirs, soil moisture, streamflow, & vegetation aridity--are at extremely dry levels for mid-winter. This is due to 1) ongoing long-term drought and 2) the recent 6+ week record dry/warm & windy spell. #CAwx #CAWater (3/3) Image
Read 3 tweets
Very dry conditions will continue through end of month, bringing record dry January to some portions of Central & interior Northern CA/western NV. Multi-model ensembles are suggesting a subtle westward shift in Pacific blocking ridge in early February. However... #CAwx #CAwater
However, that while westward shift in ridge axis may be enough to bring some colder & unsettled conditions, it's unlikely to be enough to offer more than light precip in most spots. And pattern shift may be short-lived, with ridging shifting back toward coast by mid Feb. #CAwx
This is another good meteorological example of why only considering individual "operational" weather model output can be misleading in broader context. The "op member" (e.g., left) is presently much wetter than the ensemble mean (e.g., right) from the same model... #CAwx #CAwater
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Interesting new analysis led by @ame_kaminari and co-authors including @epispheric demonstrating observed increases in hydroclimatic variability in California. *Increasing* 90th percentile in winter, but decreasing variability in autumn.… #CAwater
This offers some observational confirmation of climate model projections, which suggest that winter wet extremes will increase substantially with #ClimateChange even as shoulder season precipitation decreases and overall variability increases. #CAwater…
Another reflection on @ame_kaminari's analysis: it is striking how many statistically robust changes are occurring to variability & seasonality of both precip & streamflow even when mean annual values change little. Yet another example of why averages can be misleading...#CAwater
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California, on statewide basis, is now experiencing its worst drought in observational record going back to late 1800s--narrowly beating out peak of last drought in 2014-15 (as measured by PDSI, a metric that takes into account both precip & temperature). #CAwx #CAfire #CAwater
There is a clear trend toward increasing aridity in California--and yet little trend in mean precipitation. How can this be? A very strong warming trend due to #ClimateChange means same the amount of water falling from sky just doesn't go as far as it used to. #CAwx #CAwater
We explored this phenomena in research published in 2015 (finding that rising temps are the main factor behind increasing CA drought severity):…

and 2018 (increasing "precip whiplash" despite little change in mean):…
#CAwater #CAwx
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My perspective piece, "A shorter, sharper rainy season amplifies California wildfire risk," is now out in GRL. I discuss recent findings pointing toward shortening & sharpening wet season, & implications for ecology/wildfire. (1/17) #CAwx #CAfire #CAwater…
This perspective is in response to a recent analysis led by Jelena Luković showing that seasonal onset of CA precipitation has become progressively delayed (by ~1 month) in recent decades, w/ shorter but sharper rainy season. Underlying paper:… (2)
Record heat, plus late arrival of seasonal rains, have played a key role in CA's extremely severe wildfire seasons in recent years. Autumn 2020 exemplified this trend: vegetation conditions were, by a wide margin, the most flammable on record.#CAfire… (3)
Read 18 tweets
March 1st update: 2020-2021 "wet season" in California remains dismally dry in most places. In fact, wide swaths of both NorCal & SoCal are well under 50% of average precipitation. It has also been a warmer than average winter overall, despite some cold interludes. #CAwx #CAwater
Statewide average snowpack has quickly fallen from late January highs (around 70-75% of average for the date) to around 61% of average for the date as of Mar 1. #CAwx #CAwater
Outside of a brief period of possible showers across coastal SoCal on Wednesday, the next ~5 days still look very dry across most of CA. #CAwx
Read 5 tweets
In case you missed it: a "thread of threads" highlighting some of our collaborative research from 2020. How are wildfires, atmospheric rivers, floods, and other extreme events changing in a warming #climate (and in California specifically)? Read on for details: (1/8) #CAwater
A general-audience primer on the rapidly advancing science of "extreme event attribution." How do scientists approach question of whether #ClimateChange is affecting likelihood and/or severity of extreme weather events? (2/8) @ClimateChirper @danielletouma
Our deep dive into extreme #AtmosphericRiver storms in California and how they are likely to warm & intensify considerably due to #ClimateChange. (3/8) @xingyhuang @ProfAlexHall
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New research led by @ggpersad & featuring @PabloWater. Using downscaled climate model simulations, we show that there is unexpectedly high inter-model agreement re: increasing extremity of California hydroclimate due to #ClimateChange. (1/n)… #CAwater
In general, climate models agree than an increasing fraction of California's overall precipitation will become concentrated into the most intense events--and that the most extreme precip events will themselves be substantially more intense. (2/n)… #CAwater
There is also agreement that CA's already pronounced precipitation seasonality will become even sharper--with more rain concentrated into winter months at expense of the autumn & spring. Consider the wildfire season implications... (3/n)… #CAwater #CAfire
Read 8 tweets

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