The calendar says it’s winter, but the weather says it’s spring. Even by Phoenix standards.
Phoenix broke another heat record this weekend when the thermometer hit 82 degrees on Sunday at Sky Harbor International Airport. That beat the 78 degree record from Dec. 14 from 2010 and marks a 56-year high.
So, is this the new winter normal? And will it cool off by Christmas? Randy Cerveny, professor of geographical sciences at Arizona State University, joined The Show to talk about this.
Full conversation
LAUREN GILGER: OK, so what’s happening here weather wise? Why are we breaking records in December?
RANDY CERVENY: Well, we are having climate change. I will say that the likelihood of breaking high temperature records is much, much greater than of breaking low temperature records. We haven’t broken a low temperature record for 30-40 years. But this main event is primarily due to what’s going on in the middle of the Pacific Ocean.
We are under what is called La Niña conditions, which is a cooling of the central Pacific Ocean. And since the Pacific Ocean is so big, when you cool down a part of it, it changes the weather patterns across the world, particularly across the United States.
And what happens is that we have the jet stream — which over the last couple years has been down over us — is now way up in Oregon and Washington and they have just gotten slammed with storm after storm after storm. If you turn on the news, you’ll hear “atmospheric river” because they’re having all of these storms up there. But it keeps us really, really dry.
GILGER: And on the East Coast right now, we’re seeing tons of snow and very cold temperatures, right?
CERVENY: Right. And that’s related because the jet stream kind of acts like a giant seesaw, that if we have it moving really high to the north in the west, it’s going to dip way down to the south in the east. And so they are having some record cold temperatures along the eastern seaboard.
I was looking at Virginia today and they’ve gone 50 days now with below normal temperatures in Richmond, Virginia.
GILGER: OK, so the “Is this the new normal? Is this climate change caused? Is this the urban heat island effect?” question is sort of no.
CERVENY: No, it’s primarily driven by something that we were actually expecting to set up here in the fall, but we kind of got surprised by all the rain.
GILGER: Right.
CERVENY: This is what we should have had probably in the fall, but luckily we didn’t.
GILGER: Right. We hear La Niña and El Niño. This is the dry one. El Niño is the wet one.
CERVENY: Right.
GILGER: We were expecting a dry fall, got a kind of a wet one. What happens, Randy, when you have all that rain we got — which kind of came out of nowhere, it sounds like — and then we get these very dry temperatures and higher than normal temperatures?
CERVENY: Well, part of the problem is going to be that all that rain and then drying out allows vegetation to kind of explode across Arizona. So unfortunately, as we continue to dry out, that vegetation will start to dry out, and we’re going to have an increased fire risk. That’s going to be one of the big things we have to worry about.
GILGER: Right. So you drive across the state right now, as I did over the weekend, and you see green, like it’s much greener than normal. But you’re saying that’s all going to turn brown pretty soon.
CERVENY: Right. Unless something drastically changes with the weather patterns. And we don’t see that happening. At least for the next week, week and a half, we’re under this dome of high pressure that’s over the Western United States.
GILGER: OK, OK. And we’ll do a little forecasting in a moment. But I want to hit back on that point about climate change that you mentioned because you said, yes, climate change is happening. It’s kind of always an underly part of everything now. But this particular pattern of weather is not climate change related.
What is the climate-change-related part?
CERVENY: The climate-related part is the fact that we are hitting record temperatures. Under normal circumstances, when we have this kind of a big what we call ridge over top of the Western United States, we would have good, warm temperatures. But the fact that they are setting records is part of the underlying climate change.
That our average temperatures are continually going up a little bit year after year after year. So it makes more likely the chance of hitting a record temperature as opposed to just having a warm temperature.
GILGER: OK, OK. And that’s true on the East Coast too, with those extra cold temperatures?
CERVENY: Right. With this particular pattern, it’s allowing for very cold Arctic temperatures to come plummeting down through the Great Lakes and down into the eastern United States.
GILGER: So climate change is an era, as we’ve heard, of extremes on both ends. And here it’s most often going to be on the hot end. So a new normal in a sense in that way.
Let me ask you then about what we’re looking forward to here. A lot of folks who probably are visiting the Valley right now are happy as can be, they can go to the pool.
But I think those of us who live here kind of want to wear a sweater and maybe can’t do it. Are we looking at some kind of cool-off heading into the holidays?
CERVENY: Well, our long term forecasts are always hedged with a lot of caution. But by not this weekend but the next, Christmas weekend there, we are looking at a possibility of a storm coming down through California and then heading into Arizona. If so, that could allow for some colder air so you can wear your sweaters and even the possibility of some snow up in Flagstaff for Christmas.
GILGER: You’re saying Flagstaff might have a white Christmas?
CERVENY: Well, more likely it’s going to be the few days after Christmas. But yeah, it could possibly have some snow here by the weekend after this next.
GILGER: A white almost Christmas. All right. We will leave it there. That is Randy Cerveny, professor of geographical sciences at Arizona State University, joining us to talk more about this extra warm winter we are getting.
Randy, thanks so much. I appreciate it. You’re wearing your T-shirt. It sounds like about the right time.
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Temperatures in the Valley are projected to reach the mid- to upper 70s later in the week, which the National Weather Service said is well above what he would expect this time of year. -
A proposed Arizona bill would make it a felony to try to affect the climate or weather. -
SRP senior hydrologist Stephen Flora said while the state is experiencing a mild La Niña weather pattern, the unpredictable climate in Arizona may bring unexpected conditions this winter. -
The weather almost everywhere else except Phoenix is looking frightful. There are blizzard conditions in parts of the Northeast and Midwest, and storms in the South. -
What started as a rainy, muggy Christmas morning is expected to mostly clear up, as the rain moves east. Though the National Weather Service says some cloud cover and sprinkling may continue.
