The Big Chill Will Save California from the Big Melt

From the Cliff Mass Weather Blog

Cliff Mass

The Big Chill will Save California From the Big Melt

The media has been going big on potential disasters in California.

Drought warmings earlier this winter have been replaced by scary warming of major flooding as an incipient  “Big Melt” rapidly melts the record-breaking snowpack over the Golden State.

Desperately, California reservoir managers have been dumping water in a race to prevent reservoirs from being overtopped and potentially damaged as temperatures warm.

But it now appears that the weather gods have decided to be kind, and meteorological salvation is now in California’s future.

An incipient Big Chill is about to reduce the Big Melt to tolerable levels.

Using the European Center ensemble prediction system, the best in the world, here are the predicted differences from normal of surface air temperatures around California for the next week.  This is also called the anomaly from climatology.

Blue indicates colder than normal;  green is much colder than normal (by 8°F or more).

Wow.   Lots of green over the entire state.  The mountains above LA will be frigid.

Consider Truckee Airport at 5600 ft in the Sierra Nevada range (see below).  No heatwave there, with temperatures most nights dropping into the 20s and many days only getting into the lower 40s.

The National Weather Service’s extended temperature forecast for the entire month of May from their GFS model is for substantially cooler than normal over California.

And did I mention that Pacific Ocean sea surface temperatures along the West Coast are MUCH colder than normal?  See below.  Blue colors indicate below-normal ocean temps.

In short, such suppressed temperatures will be California’s near-term future and will greatly decrease snowmelt.

This is going to be one of the coolest Mays in California history if the models are correct. 

So let’s give this a name:  The California Big Chill.

I know your next question.  Why is California going to be SO COLD during the next week or so?

The reason:  a deep trough, low-pressure area, not unlike some of the features seen for much of the late winter.

Below is the upper-level map for 2 PM Wednesday.  The solid lines show the heights of 500 hPa pressure (you can think of this as the pressure around 18,000 ft) and the shading is the difference from normal of these heights/pressures.

An unbelievably strong low off California.  Very unusual for this time of the year.

This low sticks around for a few days and then ANOTHER strong low begins to move in from the Northwest on Monday (see below).

A cool May will allow the Sierra Nevada snowpack to slowly melt.  Reservoirs will fill but not overtop.  Flooding will be lessened.

Bottom line:  it appears that California will get through this unusually wet/snowy period without serious flooding.

But one thing is clear:  the political “leadership” in California has been deeply irresponsible during the past decades by not adding more reservoir capacity.   No new reservoirs have come online in the Golden State during the past 40 years, as the population has doubled. 

More reservoirs would not only have promoted safety by holding all the wet bounty for slow release, but would make huge water resources available for the growing population and agriculture in the State.  

There is too much talk about global warming and not enough rational planning and action to deal with the known environmental challenges of the state.


The Northwest Weather Workshop agenda and information are online.   This meeting, which will take place on May 12-13th in Seattle, is the major weather meeting of the year in the Northwest.   We have a varied and interesting agenda.  The meeting is open to everyone and if you want to attend you must register (on the website).   

We will also have a banquet/talk at Ivar’s Salmon House on Friday May, 12.  This is a fun meeting and will be hybrid (in person and on zoom).

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May 3, 2023 6:11 am

Heat and precipation dynamics are unequivocal evidence of climate change.

More Soylent Green!
Reply to  n.n
May 3, 2023 8:28 am

And? The climate always changes.

Reply to  n.n
May 3, 2023 8:28 am

This word you used does not mean what you think it means –

adjectiveAdmitting of no doubt or misunderstanding;
clear and unambiguous.
Not equivocal;
not doubtful; not ambiguous;
evident; sincere;
without equivocation or ambiguity;
singularly clear
unmistakable, or unquestionable

Reply to  n.n
May 3, 2023 10:59 am

Heat and precipation dynamics are unequivocal evidence of climate change weather.

You’re welcome.

Joseph Zorzin
May 3, 2023 6:11 am

“More reservoirs would not only have promoted safety by holding all the wet bounty for slow release, but would make huge water resources available for the growing population and agriculture in the State. ”


Tom Halla
Reply to  Joseph Zorzin
May 3, 2023 6:16 am

If it benefits people, the greens will oppose it.

Joseph Zorzin
Reply to  Tom Halla
May 3, 2023 6:57 am

Here in the American northeast (slowly spreading across the continent) is a new movement called “proforestation”. The idea is that we must lock up all the forests- cut no more trees- so forests serve only one purpose- sequester carbon. The fact that forestry provides many decent blue collar jobs, produces a low carbon footprint product (wood- and not that I care about the carbon issue), that there is a huge housing crisis in many states due to a shortage of development sites, too much regulation, high cost of wood (due to not enough forestry), too much land having solar farms built on it, etc. So, forestry is a good thing that benefits many people yet these idiots now want to end it. Since that’s what I’ve been doing for 50 years, I’m not happy about this- an understatement of course. 🙂

William Howard
Reply to  Joseph Zorzin
May 3, 2023 7:20 am

growing populations? everyone is leaving that democrat hellhole

Tom Abbott
Reply to  William Howard
May 3, 2023 7:50 am

I heard a startling number yesterday: It was said that cell phone traffic in San Francisco is down 70 percent from what it was in 2019!

Radical Democrat policies in Democrat States are killing their respective States. The people are leaving, voting with their feet. It’s a disaster for the normal people living in those areas.

Reply to  Tom Abbott
May 3, 2023 9:02 am

It’s a disaster for the people already living in the mover’s new homes, since these new residents don’t seem to be able to learn.

Reply to  Tom Abbott
May 3, 2023 10:53 am

But how much did Zoom and Teams calls increase over that time period?

Reply to  William Howard
May 3, 2023 10:52 am

Nordstroms just closed ALL their stores in downtown San Francisco citing rampant theft and local crime. They join Saks Fifth Avenue and 17 other retailers since 2020.

May 3, 2023 6:34 am

“The Big Chill”
Dont talk rubbish,
we all know the planet is on fire & the oceans are boiling (or was it the other way round ?? ), you ask the No ball prize whiner Al Gore … he’ll give you chapter & verse ( well, he won’t give; there will be a substantial fee & a private jet involved );
or Dr Thumbelina (she can see invisible gas !! ).

Never mind all this science rubbish (that was settled yrs ago) you need to get your facts from the BBC, they’ll tell you what to think !!

Reply to  1saveenergy
May 3, 2023 6:44 am

At least someone is on the ball and knows WTF is going on. (Sarc)

May 3, 2023 6:40 am

Forget reservoir capacity and flood protection. Does the region have the energy capacity to keep their citizens from freezing to death AND charge their EVs at the same time?

May 3, 2023 6:53 am

The best laugh recently was The Guardian’s report on the melt

California’s ‘big melt’ has begun and could bring perilous flooding with it

Noting the role that climate crisis has played in these cycles of crisis

Experts warned that the risks California and the wider American west is facing will only get worse as the climate crisis intensifies.

While it’s hard to attribute any one weather event to climate crisis, the harsh swings between wet and dry fit the pattern predicted by models and scientists

And yet they say…

“The climate crisis has made models and forecasts that rely on historical data less reliable”

Oh dear.

Last edited 27 days ago by strativarius
William Howard
Reply to  strativarius
May 3, 2023 7:23 am

not to worry – we can spend trillions to remove a tiny, miniscule amount of CO2 from the atmosphere which will restore the utopia and a perfect climate for all the world

Interested Bystander
Reply to  William Howard
May 3, 2023 9:49 am

yes, because before SUVs the climate was always perfect and no one ever died in a hurricane, flood or tornado.

May 3, 2023 6:55 am

But one thing is clear: the political “leadership” in California has been deeply irresponsible during the past decades by not adding more reservoir capacity.  No new reservoirs have come online in the Golden State during the past 40 years, as the population has doubled. 

You just imagineer these things to fix the weather-
‘You can’t close Eraring’: Former Snowy Hydro CEO (
What would he know as he clearly lacks imagination for the vision splendid-
Snowy Hydro boss Paul Broad resigns amid Snowy 2.0 project delays – ABC News

Reply to  observa
May 3, 2023 9:33 am

Update: And that was a supposed conservative PM at the time dreaming big-
Labor are ‘attempting what’s never been done’ with your money: Chris Kenny (

Reply to  observa
May 3, 2023 11:32 am

Snowy 2.0 is a pumped hydro project, that will use extra solar and wind power, to move the water uphill to the reservoir. Sounds like a winner! (Sarc)
– – – – – – – – –

About Snowy 2.0
Snowy 2.0 is the next chapter in the Snowy Scheme’s history. It is a nation-building renewable energy project that will provide on-demand energy and large-scale storage for many generations to come.
Water will be pumped to the upper dam when there is surplus renewable energy production and the demand for energy is low, and then released back to the lower dam to generate energy when electricity demand is high.

Thomas Finegan
May 3, 2023 6:56 am

No new reservoirs have come online in the Golden State during the past 40 years, as the population has doubled.

Diamond Valley Reservoir is in Southern California was built in the 1990’s. It holds 800,000 acre feet of Colorado River water but cannot capture any Sierra snowmelt.

Reply to  Thomas Finegan
May 3, 2023 11:03 am

Filling of the Diamond Valley reservoir, by way of the Colorado River Aqueduct, began in 1999 and was completed in 2003. Every bit of the 800,000 acre feet of water was pumped uphill 5 times in order to fill it. Water falls from the sky for free and runs downhill for free. But this does not happen at all at the Diamond Valley Reservoir.

Last edited 26 days ago by doonman
Michael in Dublin
May 3, 2023 7:05 am

No new reservoirs have come online in the Golden State during the past 40 years, as the population has doubled. 

This sounds very much like what has happened in South Africa. Five of the six by far largest dams were built between 1970 and 1980 and one in 1939. Since 1980 the population has more than doubled. However, water problems are being blamed on climate change not a corrupt and incompetent government.

Ben Vorlich
Reply to  Michael in Dublin
May 3, 2023 7:35 am

UK too last two major reservoirs Keilder 1981 Carsington 1991. Although the latter is pumped storage rather than a traditional reservoir.
Although Keilder is the biggest in Europe but as far away from London and the South East where the people are as it’s possible to get in England

Reply to  Ben Vorlich
May 4, 2023 5:52 am

Interesting. Reservoirs are normally fairly static, whereas people normally are equipped with feet. Here’s a novel idea – why not move the people to the water?

Interested Bystander
Reply to  Michael in Dublin
May 3, 2023 9:53 am

All of the useable watersheds have already been dammed in CA. That’s one reason no new dams are being built. The only feasible alternative to building new dams is to expand and raise existing dams. Some work has been going on in that vein but not nearly enough. CA is going to have to build desalination plants and figure out a way to recharge its aquifers in the bountiful years.

The small electic company I worked for has 7 small hydro dams. For 50 years proponents have wanted to build a pumped storage project on the American River project. After spending several $ millions in engineering studies the project was once again dropped in 2014. The reason given was the cost but I suspect resistence from the tiny rural community and professional climate protesters had a lot to do with it.

Last edited 26 days ago by Interested Bystander
Reply to  Interested Bystander
May 3, 2023 11:17 am
Rud Istvan
May 3, 2023 7:29 am

This ‘Big Chill’ is good news for another reason than fewer floods. The slower the snowpack melts, the more it recharges groundwater downslope that has been severely depleted in the Central Valley agricultural areas.

Ron Long
May 3, 2023 7:58 am

Maybe the “Big Chill” will only delay the inevitable melting and flooding. And, like they say, Justice delayed is justice denied. Wait for it.

John Oliver
May 3, 2023 8:09 am

The age of reason is over. I tried to spend some time recently “listening” to the “ other side” on number of current issues ( all woke)be it AGGW or trans rights or Biden border policy or the latest assault on say the Supreme court( really dangerous stuff there). It is all insanity. All text book examples of fallacious reasoning topped off with conflation or really just no reasoning at all. Just mass movement mob mentality psycho social babble. And rage and resentment- very mentally unhealthy individuals leading these movements.

I hope there is enough of our society left after “ peak insanity” for us to rebuild.

Reply to  John Oliver
May 3, 2023 11:09 am

Don’t worry. Once we capture all that atmospheric CO2 and put it underground the climate crisis will be over. I don’t have the slightest idea why that’s OK but storing nuclear waste underground isn’t. But I’m sure Jane Fonda can tell you.

Reply to  John Oliver
May 4, 2023 8:51 am

Here’s a great example of climate change gibberish published in our local rag.
No actual facts, just somehow magically saving $2B on heating using heat pumps in a climate where they don’t actually work. Just trust us. Complete insanity.

The Deerfield Valley News - VBSR.jpg
Steve Keohane
May 3, 2023 8:13 am

These lows may cause problems for the western slope of the southern Rockies which are currently melting and runoff is full bore. We don’t need more precipitation.

More Soylent Green!
May 3, 2023 8:26 am

Once again, my persnickity nit-picking on average versus normal. Yes, meteorologists commonly misuse “normal” instead of “average.”

Let’s not use “normal” unless we’re trying to imply the weather or other observations are abnormal, please. Let’s not feed into extreme weather hysteria. Normal is actually a very broad range of conditions.

Reply to  More Soylent Green!
May 3, 2023 11:22 am

Average weather is not normal. It occurs only occasionally. For example, the average monthly temperature for an area only occurs briefly in the morning and evening of most days. We almost every have an average annual rain fall year in California. It’s either dry or wet.

Peta of Newark
May 3, 2023 8:36 am

Too late for many of you young whippersnappers but Big Chill was one of the places where some of us learned to dance.(in the big blue tent)
an invaluable skill

It was overtaken/spoiled by bright young things who imagined they were The Cleverest Things In Creation because/when they’d snorted Coke.

Like Climate Science, nothing could be more wrong

Big Chill 2005.jpg
Reply to  Peta of Newark
May 3, 2023 4:44 pm

they were The Cleverest Things In Creation because/when they’d snorted Coke.”

I tried snorting Pepsi !! … is that why I’m not ‘ The Cleverest Thing In Creation’ ??

Last edited 26 days ago by 1saveenergy
May 3, 2023 10:47 am

California has other problems. California one party government has managed to take a 98 billion dollar surplus and turn it into a 25 billion dollar deficit in just one year.

May 3, 2023 11:11 am

A cool May will allow…  will fill… will be lessened.” Models. We like them when we like them. The ones we like most often must be the best ones.

No new reservoirs have come online in the Golden State during the past 40 years, as the population has doubled.” A statement like that should become common knowledge if it isn’t. I did not know. I wonder whether reservoir capacity is built out for a typical 1980-2020 spring, as hydroelectric dam capacity seems to have been built out for typical 1940-1980 economics.

May 3, 2023 2:44 pm

That’s why I didn’t surf the LA beaches in the spring! Hate cold water….much prefer snorkling the reefs in 80ºF in the USVI.

May 3, 2023 2:44 pm

The Big Chill! I like it!

May 3, 2023 3:20 pm

Maybe some Californians will wake up after this year of heavy rain and snow and tell their state government “We should have had more dams and reservoirs to slow down the flooding”.

But then California could have some droughts in future years, after which people will complain, “We should have had more dams and reservoirs in 2023 to save all that water for this year”.

Californians need to re-read the story of Joseph (great-grandson of Abraham) in the Bible, who predicted to the Egyptian Pharaoh that there would be seven years of plentiful harvests followed by seven years of famine. Pharaoh at that time heeded Joseph’s advice, and built huge barns to store the overflow from the seven years of plenty, which were later used to feed the people during the seven years of poor harvests.

Governor Gruesome needs to apply the lessons of ancient Joseph to the present day, only substituting dams and water for the ancient Pharaoh’s barns and food. California had its year of plenty–what will they do with the abundance now for the dry years to come?

May 3, 2023 4:53 pm

Nice report Cliff.

Steve Oregon
May 3, 2023 8:04 pm

With all due respect for Cliff, I believe he may have this wrong. The cold spell will delay the melt. Whereas normal weather is needed to quicken the pace of melting given the massive amount there is to melt. This cold spell has it still snowing in the Sierras. There’s not a lot of melting. The southern Sierras has 341% of normal for this date. The Kerns River water shed has 422% of normal runoff coming with the melt.

1983 Utah flooding seems to be the historical model that makes my point.
That year a record snowpack and long cold spell deep into May lead to a heat wave, intense snow melt & hefty flooding.

In late May, the combination of record snowfall, a long cold spell, and then five days of 80 degree temperatures leading up to Memorial Day weekend triggered intense snow melt, which caused severe flooding along the Wasatch Front. Flood waters were diverted, causing a temporary river down State

As Utah marks the 40th Anniversary of the 1983 floods, some similarities exist this year. The state has received record snowpack with record snow water equivalent (30″ in 2023 compared to 26″ in 1983). This year, Utah has already seen isolated incidents of flooding due to record snowpack, and there is potential for widespread flooding depending on temperatures and the rate of melt and runoff.

If the cold spell continues as Cliff suspects and an 80 degree heat wave in the Sierras occurs the millions of acre feet of snow melt water will overflow almost everything down slope.
2 million acre feet is forecast to enter Tulare Lake. If the melt is intense no containment will be possible.

Paul Stevens
May 4, 2023 3:46 am

Cliff Mass is always so balanced and rational. Reading his posts is like taking a cool drink of water after crossing a desert.

moringa man
May 4, 2023 1:58 pm

The best part of this whole thing is my garden still has peas and some spinach in Tucson in May. I just wish just once they would have one good thing to say about the weather. I have turned so many on to this great website over the years and as no predictions have ever come true they can go pound sand.

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