MILES PARKS, HOST:
It has been a historic weather week in Texas as the start of summer brought with it a brutal heat wave that is shattering records. San Angelo, in the center of the state, set an all-time high temperature record at 114 degrees. That's three degrees hotter than the previous hottest temperature ever recorded there. And the heat is expected to continue into next week because of a weather phenomenon known as a heat dome stretching across Texas and into Arizona, Louisiana and New Mexico.
We're joined now by National Weather Service meteorologist Victor Murphy. He's based in Fort Worth, Texas. Hi, Victor.
VICTOR MURPHY: Good morning.
PARKS: Tell me a little bit about what it's felt like outside this week.
MURPHY: For the state of Texas, it's sort of been a case of pick your poison. Parts of the state, as you mentioned earlier, have seen all-time record high temperatures, and that's basically been the southern part of the state - so maybe a line from San Angelo down to about Corpus Christi southward or so. The other side of the coin has been just very, very high dew point temperatures, which is a way of measuring the amount of water vapor in the air or the amount of moisture in the air. So it's been a combination of just flat-out heat and heat and humidity combined to have record high heat index values.
PARKS: And so this phenomenon is brought on by what's known as a heat dome. Can you just explain what that is?
MURPHY: Well, the heat dome is basically a large area of high pressure aloft, very stable. The stability of the atmosphere and the warmth of the atmosphere and that layer pretty much precludes any development of any clouds or even showers - just a lot of hot air trapped in that layer. And it's been a very persistent heat dome across Mexico for the last month or so. And that heat dome is sort of been waxing and waning northward, if you will. And as it moves north into Texas, like it did during the past week, we get all this extreme heat.
Bad news is, for next week, looks like that heat dome should probably move far enough north where it actually is centered over south Texas, say the Rio Grande Valley. And as a result of that, the area that the heat dome encompasses is going to include not just Texas, but also New Mexico, Oklahoma, Louisiana and Mississippi.
PARKS: I think the thing on many listeners' minds is, how does climate change play into all this? I mean, is it fair to say that these temperatures are a direct cause of climate change? Or what's the connection here?
MURPHY: Well, it's hard to attribute one specific event to climate change, but I do see a couple of climate change fingerprints, shall we say, at the scene of this crime. And the two fingerprints that I see are, number one, when you have climate change, you get less difference in temperature between the tropics and the - say, the North Pole. So as that temperature difference decreases, the jet stream decreases as far as its strength goes, you tend to end up with this blocky pattern of sort of ridges or troughs, areas of high pressure or low pressure just sort of being stuck in place. That's the one fingerprint of climate change that we're seeing in this event.
And the second one would be the increase in these dew point temperatures. The amount of water vapor that's available in the atmosphere, the amount of water vapor that the atmosphere can hold, increases. And as a result of that, you tend to see these higher dew point temperatures. So that's the second fingerprint. I think those are the two main fingerprints that we're seeing of climate change in this event right now.
PARKS: So this heat is going to touch millions of people's lives, Victor. Can you just give some advice for people who are living in some of these places on how they can stay safe during this time?
MURPHY: Yeah. It looks like we're going to have about 30 to 40 million-plus people under heat advisories or excessive heat warnings next week. So any kind of outdoor activity, you want to do it very early in the morning or late in the evening. You know, if you don't need to go outside and do any kind of outside work or outside labor, don't do so. Just stay indoors if you can.
I should point out that heat is the leading source of fatalities across the United States over the last 30 years on average. There's been about 160 heat fatalities per year. Heat can kill you, and be wise as far as decisions you make, as far as going outdoors and staying outdoors or doing hard physical labor outdoors.
PARKS: Meteorologist Victor Murphy with the National Weather Service in Fort Worth, Texas. Thank you so much, Victor. And keep drinking water.
MURPHY: Thank you, sir. Transcript provided by NPR, Copyright NPR.
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