Daniel SwainThe following is an excerpt with permission from the
By Daniel Swain of Weather West
Wild times in the California weather world
Welp, here we go again. After a long period (a full season, really) of different kinds of exceptional weather conditions all around California, there’s yet one more big storm to come in the immediate future (discussed below). But what has transpired in the past, oh, 48 hours or so? Well:
- A “Pineapple Express”-type atmospheric river brought very heavy precipitation (heavy low-mid elevation rain, including atop an existing snowpack in many places, and extremely heavy high elevation snow) to central California. Widespread and locally serious flooding occurred in the Southern Sierra watersheds (including Kern and Tulare watersheds) as well as in the agricultural centers of Monterey/Santa Cruz Counties (especially the community of Pajaro, near Watsonville, that has been completely inundated by rising waters caused by a nearby levee break on the Pajaro River).
- Despite lower and middle elevation snowmelt, the addition of new high elevation snow and absorption of rainwater by the snowpack at middle elevations has resulted in what appears to be a new record regional snowpack (in terms of SWE) for the Southern Sierra, and possibly also for the Central Sierra. These snowpacks will likely grow yet more this coming week–exceeding all-time record levels by an even wider margin. Although this record SWE will most likely not contribute substantially to flood risk this week, I am becoming increasingly concerned what it may imply regarding flood risk from late March through April or May. (Stay tuned.)
- The “break” between storms in NorCal has been anything but in some localized spots. Yesterday, several areas of thunderstorms developed in the Central Valley, including isolated true “supercell” thunderstorms that ultimately produced damaging large hail, flash flooding, and at least one confirmed tornado in the Central Valley and lower Sierra foothills. Additional isolated severe storms are possible this afternoon, posing hazards in their own right but also keeping soils saturated ahead of the next big storm.
Another moderate to strong atmospheric river Mon-Tue may produce “outsized” flood and wind impacts due to extremely wet antecedent conditions
There is an unusual amount of uncertainty for such a short-range forecast regarding exactly how the Mon-Tue atmospheric river will look at the point of landfall, and this has some pretty consequential implications for flood and wind damage-related impacts. Here’s a quick overview:
A moderate to strong atmospheric river, once again with deep subtropical origins (i.e., the “Pineapple Express”) will make landfall in northern and/or central California–bringing a period of widespread moderate to heavy rainfall to a wider swath of the state than the Friday event (i.e., some moderate to locally heavy rainfall will extend into most of SoCal as well). Unlike the previous event, this AR will be associated with a rapidly deepening surface low rather close to the NorCal coast. This will raise the potential for widespread and possibly damaging winds well beyond what was observed in the previous storm. It will also potentially amplify the AR on final approach, depending on precisely how much the surface low deepens.
ECMWF depiction of strengthening surface low attached to strong atmospheric river making landfall in California late Mon into Tue.
The GFS and ECMWF ensembles do not currently agree regarding how strong the AR will be, and the difference stems from a disagreement over the strength and exact position of the above-mentioned surface low. The ECMWF is strong and closer to the NorCal coast with the surface low, and hence its depiction is of a much strong AR affecting primarily NorCal (and, to a lesser extent, Central CA). The GFS is weaker with the surface low and therefore more diffuse with the IVT plume–making for a broader but weaker AR and a precipitation bullseye along the Central Coast and into parts of SoCal. (Why are there such big difference between models? The CW3E had an interesting discussion on Twitter this morning.)
If the ECMWF is right, expect a more powerful AR overall with a more northward focus. If the GFS is right, expect a somewhat weaker AR overall but with a broader swath of heavy precipitation across already flood-affected areas of Central CA.
Either way, this storm appears to have better dynamics (thanks to overhead jet streak and proximity of deepening nearby surface low). While I do not expect precipitation totals from this storm to be exceptional, peak hourly rainfall *rates* may well be higher with this storm (including the possibility of embedded thunderstorms in a subtropical airmass). Additionally, soils are now supersaturated everywhere across the northern 2/3 of CA (at least) and rivers are running high/actively flooding. So the higher rain rates, plus exceptionally wet antecedent conditions, pose a thread of more widespread and serious urban, stream, and flash flooding on small rivers than the Friday storm in most places. Additionally, I expect a larger number of northern and central CA rivers to flood on Tue or Wed as a result of the heavy precipitation (along with a small amount of additional snowmelt) from this storm. I *still* don’t expect widespread major river flooding with this event, though we are getting to the point that there may be some isolated major river flooding along the Central Coast and in the San Joaquin Valley (especially places that are already having problems).
Snapshot of ECMWF-predicted position of strengthening surface low near NorCal coast early Tuesday morning that could portend storm “overperformance” potential in the northern half of the state.
I would also expect to see pretty widespread wind-related issues in NorCal with this event, especially if the ECMWF’s deeper surface low is correct. Pattern recognition suggests this kind of setup tends to “overperform” in the wind and rain rate department even if 24 hour totals are not that extreme, so this storm could well have notable impacts in some areas (the very wet soil damage also compounds potential tree damage/power outage potential when combined with strong winds at the end of a storm cycle).
The ECMWF ensemble suggests that the Mon-Tue atmospheric river will be a moderate to strong event, with impacts bolstered by very wet antecedent conditions and presence of a strong nearby surface low.
Hints of relief in the long range: still active, but less wet and stormy
I don’t have much time to discuss the long range except to say that it will probably still be active to some extent, but there are decent ensemble signals suggesting attenuation of the high amplitude flow pattern and a slowing/weakening of the California snow parade. Following the Mon-Tue storm, I don’t see any obvious candidates to produce major flood/wind impacts for the foreseeable future despite ongoing episodes of light to moderate precipitation at times–so storm and flood recovery prospects improve quite a bit after Wednesday. Stay safe out there!
An excerpt from:
https://climate.nasa.gov/news/2740/climate-change-may-lead-to-bigger-atmospheric-rivers/
By Esprit Smith,
NASA’s Jet Propulsion Laboratory
A new NASA-led study shows that climate change is likely to intensify extreme weather events known as atmospheric rivers across most of the globe by the end of this century, while slightly reducing their number.
The new study projects atmospheric rivers will be significantly longer and wider than the ones we observe today, leading to more frequent atmospheric river conditions in affected areas.
“The results project that in a scenario where greenhouse gas emissions continue at the current rate, there will be about 10 percent fewer atmospheric rivers globally by the end of the 21st century,” said the study’s lead author, Duane Waliser, of NASA’s Jet Propulsion Laboratory in Pasadena, California. “However, because the findings project that the atmospheric rivers will be, on average, about 25 percent wider and longer, the global frequency of atmospheric river conditions — like heavy rain and strong winds — will actually increase by about 50 percent.”
The results also show that the frequency of the most intense atmospheric river storms is projected to nearly double.
“The study relied on two resources — a set of commonly used global climate model projections for the 21st century developed for the Intergovernmental Panel on Climate Change’s latest assessment report, and a global atmospheric river detection algorithm that can be applied to climate model output. ” I’m sure that model put forth by the Intergovernmental Panel on Climate Change has no bias whatsoever, and has been ever so accurate predicting things like CA’s drought being the “new normal”, and “the world is going to end in 5 years” every 5 years…. How often do the models need to be wrong before people question their accuracy? So climate change is responsible for our “new normal” CA drought but climate change is also responsible for increased atmospheric rivers which end / prevent droughts? There aren’t many things you can have both ways but I guess climate change is one of them.
Actually, the climate projections relied on by the IPCC have been on the conservative side, as the data coming in are showing. Also, climate change is not one sided – you can have it both ways with extreme weather. For example, as the arctic warms, the jet stream is displaced, bringing colder air farther south
Some clues for you:
Denier Myth #6 – Models Are Unreliable
https://skepticalscience.com/climate-models.htm
Denier Myth #24 – Extreme Weather Isn’t Caused by Global Warming
https://skepticalscience.com/extreme-weather-global-warming.htm
“So climate change is responsible for our “new normal” CA drought but climate change is also responsible for increased atmospheric rivers which end / prevent droughts?”
Yes, this is true. A warmer atmosphere has a greater capacity for holding moisture.
Look up “The Great Flood of 1862” in California. Nothing like it has occurred since. Half the Central Valley was turned into a lake, and Sacramento was under 30’ of water. The entire region was affected by that incessant atmospheric river event.
Here’s just one link to that significant event in California’s history:
https://www.activenorcal.com/remembering-the-great-flood-that-put-northern-california-under-30-feet-of-water/amp/
Thanks for the link Shasta.
https://rationalwiki.org/wiki/Not_as_bad_as
This looks like a substantial amount of rain in a day for this area. The county and schools seems to be very inconsistent with how they order evac or warnings or cancel schools. Sometimes it’s too much; then it’s too little. Objectivity is hard to find. Well, hopefully folks in the danger zone get ahead of time and be prepared.
GUSD just followed the freak out culture for weather and CANCELLED school for tomorrow. Wow.
Never forget Basic irrationally and (obviously) wrongly ass-umed that a man wearing a mask moderating a discussion on Zoom was alone and arrogantly and offensively attacked him for wearing the mask. That man was well known to have twice had cancer and had a splenectomy and is therefore immunocompromised. A number of things can be gleaned from this, but the most important is that Basic’s opinions and pronouncements are forever and always worthless.
Yeah, better sorry than safe!
How many times have we gotten this kind of projected rainfall amount of > 3-4 inches in a day with a saturated ground, mostly during daytime in the past 10 years? Probably half a dozen. With the traffic hazard and road congestion, it’s a good call by the district. Relax and enjoy a day off! Nothing is lost except guaranteed panic during dropoff/pickup hours.
Hardly a rare event. One clue as to the rareness of the event is when there is a nickname (Pineapple Express) associated with said event. The nickname means it’s fairly common and has happened thousands of times in the past, and will happen again, and again and again in the future. It’s really amazing how folks can get all upset about this non-rare event when people do not accept their wrong view that it is rare…when it’s not….LOL!
Yeah, record-breaking events have now become common, since we’re pumping energy into the atmosphere through radiative forcing.
8:51pm yes:
https://www.weforum.org/agenda/2022/05/8-climate-change-records-world-2021/
https://www.theguardian.com/environment/climate-consensus-97-per-cent/2017/jan/23/were-now-breaking-global-temperature-records-once-every-three-years
Are these storms any different than the storms, floods and mud slides of the past decades?
And the bit you ignored:
“Daniel Swain, a climate scientist at the University of California, Los Angeles, told us all extreme weather events are the result of multiple complex and interrelated processes happening across time and space. Therefore, climate change is not “the singular cause” of the storms. But did it affect the storms’ intensity?
“Here, the answer is probably yes, climate change thus far has likely increased both the intensity and likelihood of seeing such an intense period of precipitation in California,” he wrote in an email. “But then the question becomes: to what degree?””
And the thesis of the article that you’re missing: “I don’t think we have evidence to show the degree these events are connected to climate change,” Duane Waliser, chief scientist at NASA’s Jet Propulsion Laboratory, told us in an email.
Waliser, who has studied atmospheric rivers and climate change’s effects on them, told us it would require more study to quantify an estimate of the effects of climate change on the storms. “[U]ntil that happens, A STATMENT ALONG THESE LINES WOULD BE COMPLETE SPECULATION,” he wrote.
O’Brien agreed. He said it is impossible to make a “formal statement” about the effect of climate change on these storms without a detection and attribution study.
and then there’s “complete speculation” which is what it is in this case per the NASA JPL scientist who studies this exact thing.
But go ahead and base your understanding of atmospheric rivers on what a chief scientist studying atmospheric rivers at NASA’s JPL calls “complete speculation”.
There’s speculation, and there’s informed speculation.
In case you glossed over that clause, it was referring to quantifying the level of the effect, not whether it exists.
To answer your question RUBAIYAT, no they aren’t any different, we just haven’t had that many the past several years, thus the drought we were in.
Probably the wrong answer, but simple answers usually are.
1:12PM: You seem to be willfully misunderstanding what you are quoting:
“I don’t think we have evidence to show the degree these events are connected to climate change,”
So that *degree* might be between X and Y. You’re assuming it’s 0%-100%, but it could be, say, 80%-90%.
“Waliser, who has studied atmospheric rivers and climate change’s effects on them, told us it would require more study to quantify an estimate of the effects of climate change on the storms. “
The key word is *quantify*. We know there’s an effect, but we don’t have evidence required to put a *specific number* to it.
“[U]ntil that happens, A STATMENT ALONG THESE LINES WOULD BE COMPLETE SPECULATION,”
Yes, attaching a *specific number* to it would be completely speculative. But it is not speculative that there is some relationship.
“O’Brien agreed. He said it is impossible to make a “formal statement” about the effect of climate change on these storms without a detection and attribution study.”
The key word here being, of course, “formal”, which again refers to an exact quantification. But that there’s a relationship is not in doubt (by honest informed people). As Swain says, “the question becomes: to what degree”. misrepresenting this as there being a question whether there’s any relationship at all is grossly dishonest.
https://www.factcheck.org/2023/01/its-too-soon-to-attribute-the-california-storms-to-climate-change-experts-say/
“There is a good scientific basis to think that storms, including the type that struck California, are generally becoming more extreme due to climate change.”
Scientists say that it’s “too soon to know” because scientists are epistemically conservative and are reluctant to claim to *know* something *until* they have studied it and have hard evidence. But they damn well expect to find such evidence and reach such a conclusion eventually, given what is already known.
The argument made by the climate science deniers is the same as the one made by tobacco companies in regard to *specific instances* of lung cancer–it’s hard to prove that a specific instance of lung cancer was caused by smoking. But everyone–especially the tobacco companies–damn well know that smoking causes lung cancer.
Atmospheric scientists are saying that AGW has probably increased the intensity of the atmospheric rivers. Stay tuned.
https://www.factcheck.org/2023/01/its-too-soon-to-attribute-the-california-storms-to-climate-change-experts-say/
Can we say whether or how much climate change impacted this particular series of storms?
Not yet, climate experts say.
“I don’t think we have evidence to show the degree these events are connected to climate change,” Duane Waliser, chief scientist at NASA’s Jet Propulsion Laboratory, told us in an email.
Waliser, who has studied atmospheric rivers and climate change’s effects on them, told us it would require more study to quantify an estimate of the effects of climate change on the storms. “[U]ntil that happens, A STATMENT ALONG THESE LINES WOULD BE COMPLETE SPECULATION,” he wrote.
O’Brien agreed. He said it is impossible to make a “formal statement” about the effect of climate change on these storms without a detection and attribution study.
Yes, these current storms are different in their frequency and intensity.
That’s why the snow pack is setting records:
https://www.msn.com/en-us/weather/topstories/sierra-snowpack-hits-record-levels-after-recent-storms/ar-AA18yLh9
The storm that hit in 1862 is a regular event for the state. Here’s an interesting article about it:
https://www.earthdate.org/episodes/atmospheric-rivers
The past occurrences are known based on sediment deposits, and here’s an excerpt:
“Sedimentological records show that extreme storms and flood events occur every 150-200 years.”
“Silt deposits record megafloods that occurred in AD 212, 440, 603, 1029, 1300, 1418, 1605, 1750, 1810 and 1861-1862—ranging from 51- to 426-year intervals with a mean return period of 150-200 years.”
“Storms in 440, 1418, 1605 and 1750 were more intense than the 1861-1862 event; the storm in 1605 deposited 2 in (5 cm) of silt in the Santa Barbara Basin, indicating that it was 50% more powerful than any of the others.”
When the next one happens it will be an unimaginable disaster.
Especially now that we are amplifying even the events that really are normal, and not exceptional like the ones you cite.
“regular” and “extreme” are different things.
Anyway, it’s completely irrelevant–it’s a fallacy of relative privation and a strawman fallacy. And you don’t even have the courage to make an explicit argument–you just mention these outliers as if their mere existence contradicts climate science. But climate science does not ignore or deny natural variability. Of course there is natural variability–*and* there is anthropogenic global warming … the existence of the former doesn’t contradict the latter–to think so reflects the poverty of logical reasoning among climate science deniers.
https://www.ipcc.ch/site/assets/uploads/2018/02/ar4-wg1-chapter9-1.pdf
(from page 702)
Frequently Asked Question 9.2
Can the Warming of the 20th Century
be Explained by Natural Variability?
…
Although natural internal climate processes, such as El Niño,
can cause variations in global mean temperature for relatively
short periods, analysis indicates that a large portion is due to
external factors. Brief periods of global cooling have followed
major volcanic eruptions, such as Mt. Pinatubo in 1991. In the
early part of the 20th century, global average temperature rose,
during which time greenhouse gas concentrations started to
rise, solar output was probably increasing and there was little
volcanic activity. During the 1950s and 1960s, average global
temperatures levelled off, as increases in aerosols from fossil
fuels and other sources cooled the planet. The eruption of Mt.
Agung in 1963 also put large quantities of reflective dust into
the upper atmosphere. The rapid warming observed since the
1970s has occurred in a period when the increase in greenhouse
gases has dominated over all other factors.
Numerous experiments have been conducted using climate
models to determine the likely causes of the 20th-century climate change.
These experiments indicate that models cannot
reproduce the rapid warming observed in recent decades when
they only take into account variations in solar output and volcanic activity.
However, as shown in Figure 1, models are able
to simulate the observed 20th-century changes in temperature
when they include all of the most important external factors,
including human influences from sources such as greenhouse
gases and natural external factors.
Nope. This is ordinary weather variation for California. I will always remember the severe droughts of the mid 1970s up in Northern California which were brought to a sudden end just like this year. Massive snow accumulation then warm atmospheric river events melting a lot of the snow in a short period.
The UC Berkeley Central Sierra Snow lab at Soda Springs wasn’t founded until 1946. ‘The most in recorded history’ really means the most since 1946 when the data started being systematically recorded. Read up on the great flood of 1862 and pray it doesn’t recur in your lifetime, the lifetime of your kids, grandkids, and etc.
Okay, thank you for the information, so you’re saying that this has only been tracked for about ninety years. And unless I’m misunderstanding, the snow pack is the highest recorded in that ninety years. That seems like a pretty significant deviation from whatever the “norm” is over that time.
Not to say that over ten thousand years it would be considered significant, but I still fail to see how the greatest single instance over ninety years could possibly be the “norm.”
The deviation from the mean, not that it’s the highest in X number of years, would be the indicator of whether it’s normal or not.
Deniers love to bring up some unique incident in the past to counter a modern record-setting event, even if it refers to an ancient mass extinction event. That happens even if the last X out of X + 1 years has set a record.
So you don’t believe Santa Barbara proper was formed with alluvial flow?
If you are from some state that has 4 seasons then you need to live here for at least 40 years to understand what the weather is HERE, not where you are from where people live by the seasons.
My better half has a saying for that “we have seasons, just not the shitty ones”.
I like to say “we have 5 months of spring and 7 months of fall”.
“This is ordinary weather variation for California.”
Nice gaslighting. This weather variation is happening around a midpoint that is not unchanging — the average global temperature has a sharp upward trend: https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/global/time-series/globe/land_ocean/all/3/1850-2023
6:32 – Nice call of “squirrel!” from out in left field!
Do you have anything on-topic?
Shasta, huh, that’s interesting, I don’t understand how something can be “normal” and also “the most in recorded history”.
How does that work?
Climate is what you expect…weather is what you get.
La Conchita are you guys ready?