May 01, 2023

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Drought warmings earlier this winter have been replaced by scary warming of major flooding as an incipient  "Big Melt" rapidly melts the record-breaking snowpack over the Golden State.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


  1. Great article Cliff, your blogs are a breath of fresh air from the agenda most media outlets push, thanks a bunch!

  2. You a missing the real solution in Calif, where I lived for 20 yrs. It is NOT reservoirs. They help with floods, but long term reservoirs destroy river ecosystems, eventually will fill with sediment, and eliminate fish populations. Conservation, floodplain management, don't build in it and don't bail out with FEMA money past mistakes.

    1. aaaaa.... I don't think you are incorrect. This is about water supply. CA is unsustainably drawing sub-surface water and water is needed for dry periods. Only more reservoirs can solve that problem. And sediment issues are solvable...cliff

    2. All true. Its a matter of trade-offs. Reservoirs are temporary unless you want to pay huge dredging costs over time not to mention levee mtc. I lived in Lewiston, Id for 12 yrs. and the Corps of Eng. has discussed the need to raise levees in Lewiston due to loss of space for water behind Granite Dam. The value of salmon and aquatic river ecosystems can last for hundreds of yrs, hmm climate change???, is much more than 50 yrs of a dams life.

    3. My reply to this discussion would be to ask, Why are we doing so much farming in a desert state such as California? The Eastern great plains and the Midwest get more rain. Farming tales a lot more water per capita than residences do.

      And if that isn't enough land for crops, maybe we need to reopen the 1970's discussion about the world-wide population bomb and what to do about it.

    4. California produces approximately half to two thirds of the country’s fruits and nuts which can't be grown in colder climates.

    5. Ansel, only parts of the state are desert, and they aren't the part that's farmed intensively. Vast stretches of the Central Valley are marshland that was drained for farming, and then of course there is Tulare Lake, which was drained and desecrated for farming. The real question is why there is so much intensive farming in the first place, since so much of its production is just exported out of state.

  3. Wanted to say that Truckee is on the eastern slopes of the Sierra Nevada range

  4. After reading the incipient scare - mongering going on about the Big Melt, it only confirmed what many of us have known for decades regarding the climate alarmists: no matter what happens with the weather at present, there will only be confirmations of their established narrative that humanity is doomed unless we again do something immediately to avoid extinction.

  5. Agree with Keith. Yes, this is a very interesting and insightful post. I get the impression that in many parts of the west, not just California, practical reality based decision-making is in shorter supply than water itself. Keep the facts coming!

  6. CPC just updated their summer outlook and it's showing high probability for above normal temps in the west, well see.

    1. When has the CPC ever issued a long - range forecast for the summer in the PNW that was calling for below - average temps? I'm sure they've done it at least a few times in the recent past, but I can't recall any.

  7. Search on Google Earth for "Sites, CA"
    The off-stream Sites Reservoir was proposed in the 1950s. It might get built (recall the high- speed rail project) by mid-century, although someone thinks 2030.
    Wikipedia has a Sites_Reservoir page.

  8. CPC summer outlooks have been fairly accurate for the past several years, our summers have been warmer than normal so give credit were credit is do. I don't think temps this summer will be near normal like some models are suggesting.

    1. tim.... how you looked at the CPC verification numbers for summer seasonal forecasts? They are not impressive unfortunately. Did this call for the record breaking heat of summer 2021? The answer is no...cliff

  9. The daily minimum temp at my location in Bellingham on 5/2 was 50.1F, the first daily min temp in the 50s since 10/5/22.

  10. Well, another long range forecast bits the dust. CA is having the same heat wave we are and there are multiple river flood watches out.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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