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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The Winter Storm That Was… The Snow That Wasn’t February 7, 2011

The alarm went off at 2 a.m., I jumped out of bed and ran to the window. The second that I saw there wasn’t any snow I knew I was in for a long day. On the ride to work I soon found we didn’t have snow, but we did have ¼” of ice blanketing Houston. On 610 I counted four single-car accidents. Every few hundred feet on the 59 freeway a car had spun out and hit the guardrail. Police cars and ambulances had their lights flashing warning of the oncoming danger. By 2:30 a.m., 41 calls came into 911 reporting accidents. Freezing rain is the most dangerous kind of winter weather, and a sheet of black ice was waiting for all those who ventured out Friday morning. Early on our broadcast I focused on the ice, below-freezing temperatures and how dangerous that combination was, but it wasn’t until I got an e-mail from 13-year-old Emily Whisenant that I started explaining why it didn’t snow. Emily, like most kids, was hoping for the white stuff, and, when it didn’t fall, she was crushed. What was strange about most of the negative e-mails I received Friday was that they were from kids hoping to make snowmen, snow angels and enjoy Houston covered in white.

So what went wrong? I could make the excuse that Houston is one of the few major cities in the country that doesn’t have its own upper level air analysis. That means forecasters have to rely on weather balloon data from Lake Charles, La., and Corpus Christi, Texas. Lake Charles showed a very warm layer of temperatures above ground, while Corpus Christi showed a deep column of below-freezing temperatures. It turned out our air was much more like Lake Charles than Corpus, and that is one of the reasons why we got the freezing rain but not the snow. But I’m not here to make excuses. I said there was an 80 percent chance we would get snow and even forecasted 1 to 3 inches of it on the ground.

It’s forecasts like this that keep me up at night.  Looking back there isn’t much I would change, but there are some things I would do different.

First, what went right. The National Weather Service issued a winter storm watch and warning for all of Southeast Texas. These are issued when driving is expected to be treacherous. There were more than 1,000 car accidents because of the ice, and the warnings kept most people at home and safe.

Second, school districts and cities did an excellent job making the call a day before to keep kids and workers home, knowing Friday morning would be dangerous.

What went wrong? As Emily simply put it, “It didn’t snow.”

I’ve looked at all of my forecasts I made last week and two things stick out. First, and you can check this out on my webcasts that are posted below, our model, which is exclusive to KPRC Local 2, showed that it would not snow in Houston. It always showed ice. I dismissed this because every other model showed snow falling. Looking back, I should have said this was more of a possibility. Something I’m going to try on our next big weather event is a bust percentage. It’s simple: what were the chances that it wouldn’t snow in Houston? Twenty percent. Somewhere in my presentation I need to say, “What is the chance it won’t snow? What is the chance this forecast busts? Twenty percent. Will this stop e-mails like the one I received from Emily? Probably not, but I will sleep better.

Snow & Ice Moving In – Winter Storm Warning February 3, 2011

We have a classic setup to receive snow in Southeast Texas.  Low pressure moving in from South Texas picks up moisture from the Gulf of Mexico and moves over us, and below-freezing temperatures from the arctic blast will still be coming in from the north. 

The white line represents the temperature profile in the upper levels of the atmosphere.  We have a shallow layer of below-freezing temperatures along the coast.  What happens with a setup like this is rain falls but freezes once it hits the ground.  This makes freezing rain for our coastal counties and the most dangerous driving conditions.  We start with sleet in Houston this evening and the rain is freezing as it falls.  After a few hours this will all turn to snow.  We have a deep layer of below-freezing temperatures north of Houston, so all precipitation will fall as snow.  Because the temperatures have been in the 20s and 30s the snow and ice will stick and accumulate right away.   

By Friday morning we’ll have about a half-inch of ice in Galveston, 1 to 3 inches of snow in Houston, west and north with more northeast of Houston.  Be careful Friday morning, it will be dangerous on the roadways.

Click here to watch your Thursday’s webcast:

Winter Weather Alert Webcast

Snow Shots! February 23rd February 24, 2010

Third time this season it’s snowed in SE Texas. The last time that happened was in 1973.  Here are a few of the pictures that were sent into hotshots@click2houston.com.

Freeze!  It’s a stick up!

Click image to view other pictures from our Local 2 Mornings Facebook Page.

Snow in Southeast Texas! December 7, 2009

We received almost 2,000 pictures of the snow that fell December 4th.  It’s always magical when the white stuff falls in a tropical environment.  Besides the traffic accidents the people I talked to loved it!

Photo by: Tia Artisst, 4^th hole of Southwyck Golf Course in Pearland

Click the image to get all of the coverage, videos and photos from our snowfall.

Lisa and Mallory made this little guy in Alief.  Click image to see other photos. 

Photo by: Brock Anderson, Jersey Village.  This is Kate and her new snowman friend.  Click image to see how much snow fell where you live. 

Photo by: Paul Rodriguez, Rosenberg.  Click picture to watch snow videos.

Photo by: Marissa Exum, Gulf Coast Seal, Ltd. employees at Hobby Airport.

Here is the 2008 snow pictures: 2008 Snow

And the Christmas Eve snow in 2004: Christmas Eve Snow