Longest day of the year begins with haze, ushers in potential showers this weekend

EMILY BRIGHT: This is Minnesota Now. I'm Emily Bright in for Cathy Wurzer. It's 12:30 and it is hot and hazy today. Just one week ago, the air smelled like burnt tires from wildfire smoke. Well today, it's not smoke, but ozone that's bringing about those milky skies. MPR's chief meteorologist Paul Huttner is here now with me to explain more about what's causing the haze and when it will let up. Hi, Paul. Thanks for being here.

PAUL HUTTNER: Hey, Emily. Great to talk with you as always. And hey, happy summer. The solstice happened at 9:57 this morning, so--

EMILY BRIGHT: It's summer.

PAUL HUTTNER: Yeah, longest day of the year. 15 hours and 36 minutes of daylight today.

EMILY BRIGHT: Wow. So let's talk about that air quality alert.

PAUL HUTTNER: Yeah, so it's still in effect until 9:00 PM Thursday. It includes all of Central and Southern Minnesota, including the Twin Cities. But air quality right now moderate across most of Minnesota, and there's a reason for that. Ozone tends to form in the afternoon more and into the evening because it requires sunlight to hit, basically, the pollutants near the ground. And it causes a chemical reaction.

So the sunlight interacts with nitrous oxides and volatile organic compounds. Most of this comes from car exhaust, and then it forms ground-level ozone. That's bad for us at the surface. So air quality now in the moderate range around most of Minnesota. It will probably get back into that unhealthy range later this afternoon.

And Emily, it's interesting to note that there's kind of an ozone paradox. If you looked at the map of this ozone alert, you notice it's red across Saint Cloud, down around the Twin City suburbs, but it was orange in the center of the Twin Cities, so kind of a donut hole.

EMILY BRIGHT: Yeah, I saw that.

PAUL HUTTNER: Yeah. So actually, there can be less ozone right in the city center because there's a reaction that takes place, and it goes both ways. So once the ozone forms, some of it's short-lived because the nitrous oxides can kind of eat the ozone. So it can actually go down in the cities but linger in the suburbs and the rural areas. So that's why that ozone alert looks the way it does.

EMILY BRIGHT: Now, usually we're talking about a lot of different kind of severe weather right now. It seems like we've had kind of a slow start to the season.

PAUL HUTTNER: This is remarkable, because I remember last year just being deluged with severe thunderstorm and tornado warnings.

EMILY BRIGHT: Yeah.

PAUL HUTTNER: And this is one of the slowest starts on record to a severe weather season in Minnesota. This is the fourth slowest start to the severe weather season in the Twin Cities National Weather Service Office area. Those records go back to about 1986. Now, the Twin Cities National Weather Service has issued only 40 severe thunderstorm warnings so far through June 20. Last year, they had issued 426, so 10 times as many.

EMILY BRIGHT: Oh, my.

PAUL HUTTNER: And that was the highest. So we went from the most active severe weather year to one of the least actives. Tornado warnings, they've only issued four, thankfully. That's good news. Last year, 82, which was the highest also. So this is pretty remarkable, and it just goes to show you that things don't always go in a straight line in weather, Emily. We can get one extreme and another extreme, and we call that just random variability in our weather.

EMILY BRIGHT: Yeah, I think weather whiplash has been the watchword for 2023 based on my very unscientific observations.

PAUL HUTTNER: Yeah. No, there it is-- great term, yeah.

EMILY BRIGHT: There we go. Let's get the forecast. What can we expect for temperatures? And please tell me there's some chance for rain.

PAUL HUTTNER: There is some chance for rain. This is day seven of 90-degree heat. We're at 87 in the Twin Cities now. We'll get to 90 this afternoon. Tomorrow will be day eight. And the average is about 13 for the season, so we're running ahead of schedule. So mostly sunny, hot today. Tomorrow around 90 in the Twin Cities, 89 Friday, and then that chance of rain we're looking for. It's still going to be spotty, but it's coming.

Thursday morning, afternoon, I think, Northwest, North Central, Western Minnesota, a weak front moves in with scattered thunderstorms. Friday, a little better chance for the Twin Cities. And then Saturday and Sunday, a little more widespread rain around Minnesota, maybe many of us seeing a half an inch to an inch.

Some of the models saying more than an inch possible in northern Minnesota. And we're in the 80s Saturday, back into the 70s on Sunday. So there is a chance for rain. We need more prolonged rains, Emily, to dig out of this drought. But hey, we'll take what we can get. Right now, next week looks mostly sunny to partly cloudy, mainly in the 80s.

EMILY BRIGHT: OK, well I have my fingers crossed for rain. Tell me about this super El Nino that's brewing.

PAUL HUTTNER: So here's the thing. We've gone from the three-peat La Nina-- three years in a row of La Nina into an El Nino pretty quickly this year. And Noah, of course, has that El Nino advisory out. They're saying an 84% chance of a moderate El Nino. That's when those tropical Pacific Sea surface temperatures reach one degree Celsius warmer than average. They're saying about a 56% chance it could be strong. That's 1.5 degrees.

And this isn't official, but a lot of meteorologists call two degrees Celsius-- if it gets that warm in the Pacific-- a super El Nino event. And some of the forecast models that model these ocean temperatures are saying we could get there later this year. And if we do, it could just exacerbate some of the extreme weather we're seeing, like these heat waves they're seeing in Texas and Mexico, potentially impact hurricanes and tropical storms.

And for Minnesota usually, statistically a milder than average winter next year. So we'll have to watch that. But this is really something to watch. It's a big climate event and it can also add to the Earth's overall total heat. A lot of climate folks thinking this could be the hottest year on record globally-- and if not this year, 2024. So something to watch as we go through the year.

EMILY BRIGHT: Oh, my. All right, well Paul, before we let you go, what's on Climate Cast tomorrow?

PAUL HUTTNER: Yeah, there is an interesting lawsuit and trial going on in the state of Montana with some young people that are suing the state, claiming that the state Constitution gives them a right for a healthy environment. So this trial is going on right now. We're going to talk to one of the reporters out there this week, and we'll have that on Climate Cast tomorrow.

EMILY BRIGHT: All right, we'll have to listen tomorrow afternoon. NPR chief meteorologist Paul Huttner, thanks for your time, Paul.

PAUL HUTTNER: My pleasure. Thanks, Emily.