Click image to view Arctic Oscillation video.
In this video I explain what is called the arctic oscillation. It has played a big role in bringing cold arctic air into the southern part of the United States this year and last. Even though we are in the midst of big-time warm up, we will end up setting record cold temperatures for the month of February no matter how the month ends.
This is fascinating to me. Looking at the month of February in an eleven year span from 2000 to 2010, Houston had only three days in the 20s. 2011 has had five and counting.
February 1st 24 degrees
February 2nd 21 degrees
February 3rd 28 degrees
February 4th 26 degrees
February 5th 24 degrees
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.
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.
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Anthony Yanez's Weather Blog 