California – The wettest start since 2010… And more on the way January 31, 2017

I’m getting asked a lot of questions about our weather.  Why are we getting so much rain?  Why is it a year delayed from last year’s strong El Nino?  Is the drought over? What’s going on?

Four months into the water year we have the wettest start ever recorded.

To answer these questions I first have to give some perspective on climate in California and probabilities.

In case you don’t know, California is a state of extremes when it comes to precipitation.  Throughout recorded history we’ve alternated between drought and excessive rain.  Los Angeles is a good example of these extremes.  While we average 15 inches of rain a year, we are rarely near this amount.  If you look at the past 30 years, we’ve gone from extremely dry years to well above average years.  In the end, it averages 15 inches.

Next snow survey is February 2nd and we’ll near 200%.

The one question that is a little more difficult to explain is the why we’re getting the heavy rain this year instead of last year.  Last winter we were prepared for the potential of heavy rain. The reason we thought this was because in all of the significantly strong El Nino climate patterns, Southern California got soaked.  The odds were in our favor.  But the rain didn’t come.

The 2015/16 water year only recorded 6.57″ of rain.

What is fascinating this year is we are in a weak La Nina or neutral weather pattern.  Both of these patterns slant dry for the state of California and especially for Southern California.  The probability our state would be dry this year is 70%, leaving a 30% chance we’d be above average.  And, if you really study this image, there isn’t a weak La Nina pattern that is well above average for Southern California.

Instead what we are seeing is the wettest winter since 2010.  The storms of the past two months have recouped 37% of the state’s five-year snow/water deficits. And for the first time since January 2014, no place in California is in an exceptional drought.  Precipitation is more than 200% of average and the Sierra Snow pack is looking great!

So what gives? Why the two extremes in outcomes?  I could give the answer, “That is how the weather works sometimes.” And this reply wouldn’t be completely wrong because even with an excellent forecast for a 90% chance of rain, there are days it’s dry.

But the answer is a little more complicated.

Last year the water was so warm in the Pacific that it affected the jet stream and moved all of the heavy rain to the Pacific Northwest and Northern California.

This winter we’ve been aided by numerous atmospheric rivers or a Pineapple Express.  This type of pattern can occur at any time regardless of an El Nino, La Nina or neutral pattern.  These rivers of atmospheric moisture are responsible for much of the devastating flooding in California’s history.  And it played a big part in the flooding on Jan. 22.

Long Beach received the most rain ever recorded in a 24 hour period, 3.97″.

Most people don’t know about the mega flood of 1862, which was caused by an intense atmospheric river. It has a return period of 100-200 years, meaning it will happen again.

And this leads me to climate change.  The latest research shows that in a warming planet, droughts will become more severe and heavy rain events will occur more often.  Before we started getting the rain in December, Southern California went through the driest five-year stretch ever recorded.  And, if you look at tree ring data, it may have been the driest stretch in 1,000 years.

But if you look at the history of flooding in California, intense flooding events occurred before the industrial age and atmospheric rivers are responsible for most of these events.  Attributing climate change to future flooding events may be hard to do.  Upcoming research will need to address how a warming world affects atmospheric rivers.

Going forward, the key for our drought, especially in Southern California, is we need this kind of winter pattern for two more years so we can get out of a drought cycle.  And, of course, I’ll keep you posted.

 

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Southern California is Making a Comeback! February 24, 2016

It’s the fourth quarter and SoCal is down by three touchdowns. The clock is ticking and 17 million people are wondering if this will be a disappointing finish.  Don’t give up yet, this is the rain forecast for Sunday and Monday with more on the way.

With one month to go before one of the strongest El Ninos on record fades, the question remains: How much more rain and snow is on the way, and why has Southern California been so dry?

Let’s start by going back in time and look at the El Nino rain forecast for winter. A couple of things stick out. First, notice how Southern California, Texas and Florida are all forecast to receive an above average amount of rain. The Pacific Northwest is dry and Northern California is a toss up. All of the previously strong El Ninos showed no correlation to NoCal, it was 50/50.

This is what has happened so far this winter. The bonus is most of the water sheds and reservoirs, which are located in Northern California and provide water for the entire state, are filling up. But Southern California has been incredibly dry, prompting people to ask: Where is El Nino? I call this forecast the 17-million person “bust.”

What is fascinating to me is what is happening this winter in the Pacific Northwest. Seattle, Washington and Portland have recorded their wettest winters ever! Record keeping goes back to 1894.  So the question is why.

The El Nino-fueled moisture is in the Pacific, as predicted, but the jet stream has moved the rain into the Pacific Northwest and Northern California. The dry slot has been Southern California and Southern Arizona. But why is this blocking ridge of high pressure here?

You’ve heard us say, “Every El Nino is different.” And that is certainly the case this year. The warmest water in the Pacific Ocean isn’t near South America like it was in previously strong El Nino patterns. The warmest water is farther west, south of the Hawaiian Islands.

That warmth is creating a large area of low pressure and rising air.

In turn, the sinking air has created a large area of high pressure keeping the rain away from Southern California.

The rain is back in SoCal March 6th and the longer term climate models have a wet March but these same models also showed a furry of storms in February and obviously that hasn’t happened. So, what do you think will happen?  You can Tweet or Facebook me at: @anthonynbcla.

Time is running out, the clock is ticking and 17 million people are wondering if SoCal can make a come back.

El Nino & California January 13, 2016

We are halfway though California’s wet season and in the three wettest months of the year. While we’ve been in an El Nino pattern since March, California doesn’t feel the effects of this climate pattern until late fall and winter.

The great news is Northern and Central California have been receiving a lot of beneficial rain and snow. In fact, our snowpack is more than double what it was last year at this time.  And some spots will get two more feet of snow in the next two days.  One-hundred percent is considered an “average” amount of snowpack for this date and we are right there. The below image is a comparison of the snow amounts on this date to January of 2014.

Jan 13, 2016 – Purple is 50-75″ of snow

Jan 13, 2014 – Blue is 8″-12″ of Snow

Our Northern California reservoirs are key to building up our water supply as these are the largest and provide water for the most people and land.

So What About Us In Southern California?

We got our first heavy rain last week and there was quite a bit of burn scar flooding and several mud slides. We are close to reaching our monthly average halfway through the month.

No two El Ninos are the same. In 1983, most of the heavy rain and flooding in Los Angeles came in the month of March. In 1998, six storms brought more than 13 inches of rain in February. On average, we get six storms throughout an entire year.

If you are wondering how much rain we need to erase the deficit in Southern California, we’ve got a long way to go.

Our El Nino will end up being the strongest or second strongest on record, and comparing the top five the range in rain amounts is between 20″ and 30″. So, unless we break a record, we’ll still have a deficit, but of course the more rain we get the better.

As of mid January our current El Nino is tied with 1997/98 and peaking right now.

 

 

 

El Niño strengthening and what that means for us in Southern California July 7, 2015

The latest El Niño forecast is in and it is looking more and more likely that we are in for a very strong El Niño through the winter of 2015-16.  There is even a 60% chance that we could experience the strongest El Niño in modern times.  So what does this mean for California and especially our drought?  Keep reading and I’ll try and answer this question.

The above image is the latest forecast for El Niño.  This shows the different models and what they are projecting.  As you can see, almost all of them are forecasting a strong El Niño with some even above the record El Niño of 1997.

Of course the big question is: Will we get enough rain in the winter to get out of our horrific drought in California or at least make a big dent in it?  One of the biggest misconceptions when it comes to El Niño is it ALWAYS brings rain.  There is the belief that every El Niño will be like 1997-98 or 1983-83 when downtown Los Angeles received 30 plus inches of rain during the water year.  The atmosphere is not that simple.  Some El Niño seasons have been dry, some wet, and others are somewhere around average.  Going back through 1950, we have seen 22 seasons with an El Niño, 12 had above-average rainfall and 10 were below-average.  This data shows a slight trend toward wet winters, but you can see it is far from a guarantee.  This is the part of El Niño that is impossible to predict.

However, the one strong correlation to getting the rain we need is if we get a significantly strong El Niño.  Check out the above graph and how all significant years brought well above average rain amounts.  If El Niño forecast continues in this direction I do think we will receive a tremendous amount of rain this upcoming winter.  To get out of our drought in California we need widespread amounts of two feet just to get back to normal.  If we get that in one season we’ll get flooding and mud slides.  We also need more than just rain.  We need our northern California mountains to get snow.  A concern I have is, if the temperatures are too warm, we’ll get a lot of rain but no snow.  The snow in the Northern Sierras is our year-round water supply for families and farmers.

Check out how our July water temperatures compare to the El Niño of 1997.  That year was warmer and more widespread from the waters of South America, but the two are fairly close.  An interesting note: Hurricane Dolores was able to keep its circulation as it moved closer to southern California because the warmer waters in North America kept it from completely dying.  It was Dolores, along with a monsoonal flow, that brought about record-setting rain July 18th and 19th.

In any El Niño season we see an increase in Pacific hurricane activity and a decrease in the Atlantic.

Even with the record-setting July rain, there is no recognizable dent in the drought.  We went from 47% exceptional drought to 46%.

What is interesting for Los Angeles in particular is we also don’t get as many 90-degree days in the summer.

El Niño is a warming of the water off the Pacific coast of South America.  El Niño’s are categorized by their strength, ranging from weak to very strong.  This past winter was a weak El Niño.  No two El Niños are alike.

Special thanks to David Biggar for the graphics and research.