Daniel SwainThe following is an excerpt with permission from the
By Daniel Swain of Weather West
Yet another extraordinary period of California weather
Well, things are finally calming down, weather-wise, in California after a rather extraordinary season. And March, in some ways, put an exclamation point on this very active period: it ended up being the coldest March on record in some parts of NorCal, and well colder than average almost everywhere else in CA. That is a truly remarkable statement, especially since the sustained centennial-scale warming trend in California has made it very difficult to experience long durations of record-breaking cold temperatures in recent decades. This very cold March has major implications for agriculture in California, and have also been part of the reason why the enormous Sierra snowpack has only just begun to melt as temperatures finally start to warm in early April.
This winter overall also ended up being the coldest in ~44 years in a statewide basis–meaning that no one born after 1979 has ever experienced a season this cold in California! And, yet, winters as cold as this one used to be relatively common prior to the 1970s, which is a dramatic testament to just how large and sustained California’s long-term warming trend has actually been and how rare record-breaking cold is today.
This winter was, of course, also exceptionally wet across portions of California. Although this year has not turned out to be among the wettest on record on a statewide basis–since far NorCal actually saw near-average precipitation–it was indeed the wettest on record across central portions of the state stretching from the Central Valley into the southern and central Sierra Nevada. This means that around two thirds of California has now experienced a “record wettest” winter at some point in the past decade–and nearly all of California has also experienced a “record driest” winter during the same period (and in some cases, more than once)!
Spring warmth and calmer weather have finally arrived, with a more typical pattern expected in coming days
A fairly typical spring pattern will likely take shape in the coming days and weeks across California–which will feel pretty warm and calm in comparison to recent months. I expect the overall North Pacific/West Coast flow pattern to be “progressive” in nature, with occasional weak spring-like systems passing through but no major or sustained precipitation events. It’s likely that the higher mountains will still see at least one or two minor additional snow events over the next couple of weeks, but not enough to offset the substantial snowpack melting that will likely occur as the strong spring sun and warmer temperatures start to work their magic. Lower elevation areas may see occasional shower chances, mainly in NorCal, but precipitation should remain near average in NorCal for April and probably below average in SoCal (and averages start to sharply decrease this time of year).
The ECMWF ensemble suggests pretty typical, and fairly unremarkable, atmospheric flow anomalies across the Western U.S. in the coming days.
Temperature-wise, conditions will likely oscillate between slightly cooler and slightly warmer than average over the next couple of weeks. The ensemble mean 500mb flow pattern for this period is “remarkably unremarkable”–with no sustained anomalies of either sign apparent. The cold nearshore ocean waters, plus the still-extensive Sierra snowpack, may exert a slight additional local cooling effect in relevant areas, too. All in all, this looks like a fairly benign weather pattern–and will allow the enormous snowpack to finally start melting more quickly (but not too quickly…for now).
Spring and early summer snowmelt flood risk looms large in/below Southern Sierra watersheds
Although no extreme snowmelt events are currently on the horizon for the next 1-2 weeks, there is still a record-breaking amount of snow water that’s going to have to come downhill at some point between now and mid-summer. We still can’t rule out a late season (late April or May) warm atmospheric river (happens every few years), and once we get into May significant heatwaves become significantly more likely. There will probably be, at some point, a significantly larger pulse of meltwater both on the watersheds draining into the Tulare Basin and southern San Joaquin watershed as well as the Owens Valley and east slope watersheds at some point between now and mid-June, but it’s still impossible to say exactly when that’s going to occur. Widespread flooding is inevitable (and already ongoing) in the Tulare Basin, and will likely get worse before it gets better. Flooding of some magnitude is also likely farther north in the San Joaquin watershed and in the Owens Valley, though just how bad things get there (minor-moderate vs. severe) will depend on whether there are any especially intense snowmelt pulses. Additionally, there is concern regarding prolonged high flow/stress on flood protection levees and the potential for eventual failures even if there are no record-breaking runoff events this spring (simply because these structures will be subjected to high stress for weeks to months on end). This will continue to be a major story in the coming weeks even as the rest of the state dries out and recovers from this winter’s damaging and disruptive events–flood risk may linger into mid-summer in some areas subject to direct snowmelt runoff.
It’s also important to note that this season has been an excellent snow accumulation period for much of the Lower Colorado River Basin–and it couldn’t have come at a better moment in the context of the extreme multi-decadal “megadrought”. One wet and cool winter does not, of course, obviate a 2-3 decade long drought–but this year will at least partially de-fuse the short term crisis that had escalated (as recently as autumn 2022) to crisis levels. Snowmelt runoff into the big CO River reservoirs in the coming months will stave off worst-case scenarios for at least a year or so, giving a little breathing room to figure of what to do in the context of the long-term sustainability crisis amid a warming climate.
El Niño update: it’s coming.
Current SST anomaly map from NOAA. It depicts a remarkably warm global ocean, punctuated by extremely warm temperatures near the tropical west coast of South America and unusually cool water near California and the west coast of North America.
At this moment in time, no person alive has ever experienced global ocean temperatures as warm as they are today (i.e., the global average SST anomaly has reached record levels in recent days). This is despite remarkably cool patches of water in two regions: the sub-Antarctic eastern Pacific west of South America, and the mid-latitude East Pacific along the coast of western North America (including along the California coast). Nearly everywhere else on Earth, the oceans are presently much warmer than the long-term average–and this is especially true near the west coast of tropical South America near Peru, where SST anomalies are locally in excess of 5C (9F). That is an extraordinary level of oceanic warmth, and is highly suggestive of the early stages of a significant El Niño event.
10 years isn’t anything. It’s an absolute zero statistically to look at 10 years here locally. Ask a science professor what 10 data points mean out of many, many thousands that naturally fluctuate. Are you arguing that climate change has struck us? You do realize your living smack dab in a Mediterranean zone climatically and saying “look at our last 10 years”?
I do think humans are influencing the climate in a negative way, but no-thought knee jerk comments like yours are useless if you’re trying to persuade anyone.
Dude…. your OWN WORDS: “to me this feels like the oldest AND wettest winter I’ve ever seen” – you said the SAME thing as I did and then you LOST IT. LOL keep scrambling chump.
BASIC – uh…. what? Who are you losing it on? I was responding the the comment that the WEATHER is the “same as it’s always been.” It hasn’t. This was a wet winter, last winter and the many preceding winters have NOT been as wet. Ergo, the WEATHER is NOT the same this year as it’s “always been.” That is all I meant and all I responded to. Calm down, you sound like an a$$.
You’re response to Rubaiyat is what it is. It sounds like you believe the last drought in an indication of something other than typical changes on our local climate. Right?
I’m not claiming anything, just simply saying ‘wet and cold’ about this winter, literally. That’s it. Anyone can disagree or agree with me. I’m coming from the simple perspective of observation, nothing more. Throwing it out to others who can think about whether they have noticed this.
That’s for the condescending ‘ass’ and ‘champ’ stuff too. Very classy.
“It sounds like you believe the last drought in an indication of something other than typical changes on our local climate. Right?” – No, you are WAY off. I simply disagreed with the WEATHER being the “same as it’s always been.” Your “useless” and “knee jerk” reaction (YOUR words) was to attack me about climate change. Again, you’re way off and missed the point.
You’re welcome, “knee jerk.”
And nobody would ever think “champ”.
7:35 – It’s weather that typically changes, not climate.
All inn all the weather is the same as it’s always been.
RUBAIYAT – No, it has most certainly “always been” like this. Did you forget the massive drought we lived with for the past 10 years?
Weather is both unique and the same. Every year is unique, no day is exactly the same. Lets say July 1 1865 was 81 degrees and so was July 1 2002 but if you do all your measurement down to the minute, it won’t be the same. Measure to the second and it won’t even be close. But it is very much the same in the macro, after all it was a warm 81 degree day. Climate is similar, there have been warming periods before and there will be more. There have been cooling periods and there will be more. There will be droughts, there will be floods. But the details will be different.
I think human beings are narcissists who constantly think the world revolves around humans
Hi sacjon
This sounds momentous
“At this moment in time, no person alive has ever experienced global ocean temperatures as warm as they are today”
OK, but that is what? 120 years? out of 4.54 billion?
Next questions:
Why were oceans so warm back 120 years ago?
Why were oceans very very warm in the 1300’s but within 20 years turned so cold we had a mini ice age, and the population of Earth actually dropped by 20,000,000 over the next 200 years?
Humans like to believe that everything, even the climate revolves around them and how much of that is hubris?
Humans do have a big impact on the earth. No one who has ever cleaned grandma’s attic or a homeless encampment would ever deny that, but there are much much larger forces than us in play.
Like the sun. Or during the cold mini ice ages it was the movement of colder water in the oceans that occurred with no human influence to speak of. Kelvin waves, all the various oscillations from the ENSO to the MJO that were doing their thing way before humans “discovered” them. The earths rotation and the sun all have far more impact on the climate than humans. A single volcano can produce the equivalent of decades of 2023 human pollution, imagine what several volcanos violently erupting at the same time could do.
10:06 – Too many falsehoods encapsulated in that outpouring of drivel to even begin to address in a comment. Please educate yourself on climate!
https://climate.nasa.gov/evidence/
https://www.bbc.com/news/science-environment-24021772
Hi Edney,
Since this article is about our current weather, not climate change in general, my comment as to the weather being the same as always, is/was limited in scope as to the current weather, being much more wet and cold (as BASIC agrees even though he doesn’t realize it) than it has been in past years.
As for climate change….. yup.
From personal observations only – to me this feels like the oldest AND wettest winter I’ve ever seen in SB (half century).
sorry, ‘coldest’…