Why The Tropics Have A Weather Forecasting Problem

Summary

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Short Wave: "Why The Tropics Have A Weather Forecasting Problem"

Podcast: Short Wave (NPR)
Original Air Date: October 10, 2025
Host: Emily Kwong
Guest: Angel Damas Coraliza, Atmospheric Scientist & 2025 MacArthur Fellow

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Episode Overview

This episode unpacks why weather forecasting in the tropics lags behind predictions made for higher-latitude regions, highlighting both scientific challenges and social implications. Atmospheric scientist Angel Damas Coraliza, recognized with a MacArthur "Genius" grant, explains how his childhood in Puerto Rico — and first-hand experiences with devastating hurricanes — fueled his mission to improve tropical meteorology. The episode dives into the science of tropical weather, its differences from mid-latitude systems, the global significance of tropical phenomena like the Madden Julian Oscillation (MJO), and calls for greater scientific equity.

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Key Discussion Points & Insights

1. Personal Connection to Tropical Weather (00:00–04:14)

• Angel Damas Coraliza's Exposure to Hurricanes:
  • Grew up in Puerto Rico, familiar with extreme weather but deeply impacted by Hurricane Georges (1998).
    • "We cannot evacuate from hurricanes because we're in an island. So we had to kind of weather the hurricane...the winds roaring and the house shaking."
      — Angel Damas Coraliza (01:03)
  • Hurricane Maria (2017) was a life-changing event:
    • "I was not able to contact my family for weeks...it was like something died with that storm." (02:01)
• These experiences motivated Angel to pursue atmospheric science, with the explicit goal of better serving his community and all tropical regions.

2. Recognition and Representation in Science (04:14–05:45)

• MacArthur "Genius" Grant:
  • Angel’s pioneering research into tropical humidity earned him the prestigious award, enabling increased visibility for Puerto Rican science.
  • "To be able to receive this award...and they tell me like, no, we see you...To me, this is everything."
    — Angel Damas Coraliza (03:40)

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3. Why the Tropics Are Understudied (05:45–07:41)

• Focus on Mid-Latitude Weather:
  • Early meteorological research centered on wealthier, mid-latitude nations (e.g., US, Europe), with less attention paid to tropical systems.
  • Local knowledge (e.g., Taino in Caribbean, Peruvian natives with El Niño) existed but was overlooked by Western scientific establishment.
    • "It's actually, I don't think it's incorrect to say that people in North America and Europe knew nothing about the tropics until World War II."
      — Angel Damas Coraliza (06:57)

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4. Scientific Breakthroughs and the Roots of Forecasting Gaps (07:41–11:15)

• World War II as a Turning Point:
  • Typhoons challenged Allied operations in the Pacific, spurring recognition of dynamic tropical weather and first real scientific efforts to understand it.
  • Herbert Riehl wrote the first English-language book on tropical meteorology in the 1950s.
    • "Before all this happened, people had just assumed that the tropics were kind of like this paradise...And then we realized that it was serious in World War II."
      — Angel Damas Coraliza (07:43)
• Fundamental Differences in Weather Systems:
  • In mid-latitudes: Jet stream drives large temperature swings (cold/warm fronts).
  • In tropics: Temperature is stable year-round; instead, moisture (humidity) drives weather cycles — rainy vs. dry periods.
    • "So in the tropics it actually gets really humid or it's really dry. That's really kind of the big thing that drives weather patterns."
      — Angel Damas Coraliza (10:03)

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5. The Problem: Poor Tropical Forecasting (11:15–11:59)

• Model Limitations:
  • Most global weather models were built for mid-latitude physics, not tropical conditions.
  • Lack of comprehensive theories and textbooks on tropical dynamics compounds forecasting inequality.
    • "The vast majority of weather forecasting models were initially built to tackle mid-latitude weather, not tropical weather...it is a problem of human safety and well-being that we cannot forecast things in the tropics as well as we do in the mid-latitudes."
      — Angel Damas Coraliza (11:15)

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6. The Madden-Julian Oscillation & New Understandings (11:59–13:59)

• Madden-Julian Oscillation (MJO):
  • Largest unknown global weather driver for most people; as important as El Niño.
    • "The MJO is actually the most important tropical phenomenon that people don't know about...It has impacts throughout the globe."
      — Angel Damas Coraliza (12:21)
  • MJO affects hurricane activity and even rainfall events in distant regions like California.
• Moisture-Wind-Rain Feedback:
  • Angel discovered that, in the tropics, moisture, rainfall, and wind are tightly coupled in a continuous feedback loop — influencing not just the MJO but possibly other phenomena.
    • "When it's humid, it starts to rain, but then all that rain actually changes the wind patterns...the moisture, the rains and the winds, they couple together."
      — Angel Damas Coraliza (13:12)

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7. Scientific Equity & the Future of Forecasting (13:59–15:05)

• The Vision for Global Weather Justice:
  • Calls for forecasting equity so people in the tropics have access to the same level of warning and preparedness as those in wealthier, better-studied regions.
    • "At the end of the day, everybody deserves to have the best possible weather forecast...And right now we don't equally have the knowledge about climate and the atmosphere for everywhere."
      — Angel Damas Coraliza (14:26)

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Notable Quotes / Memorable Moments

• On community and representation:
  "As a community, we've been invisible. And to be able to receive this award...and they tell me...we see what you're doing and we think that what you do matters. It's not just what you're doing, but what your community is doing. To me, this is everything."
  — Angel Damas Coraliza (03:40)

• On scientific priorities:
  "It's a problem of human safety and well-being that we cannot forecast things in the tropics as well as we do in the mid-latitudes."
  — Angel Damas Coraliza (11:15)

• Urgency for scientific parity:
  "Where we should be is a place where everybody knows the same amount about everywhere."
  — Angel Damas Coraliza (14:53)

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Key Timestamps

• 00:00 – Childhood, hurricanes, and shaping a scientific mission
• 03:28 – Recognition by the MacArthur Foundation
• 06:57 – Western ignorance of tropical storms until WWII
• 10:03 – Moisture as the main driver of tropical weather
• 11:15 – Limitations of existing models for tropical forecasting
• 12:21 – Why the MJO matters
• 13:45 – Feedback loops in tropical weather
• 14:26 – The case for equitable forecasting worldwide

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Final Thoughts

In just 15 minutes, this episode connects the personal to the planetary. Listeners get a crash course in why tropical weather is different, why most forecasting fails the tropics, and how scientists like Angel Damas Coraliza are working to close a global data and safety gap. With clear, candid storytelling and a deep sense of justice, the episode offers both accessible science and a passionate call for equity in forecasting — for everyone, everywhere.

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Transcript

[Emily Kwong]

This message comes from Memorial Sloan Kettering Cancer center this October. For a short time, your gift to MSK will be triple matched to help support breast cancer research, treatment and care. Donate [e-mail] match hey, shortwavers, emily Kwong here. School has been back in session for a while now, but grades are due for Short Wave. What would you give us? An A, A B, a C? We want to know. Leave us a rating or a review on Apple, podcasts, on Spotify, on whatever platform you use to listen, and we will take your feedback seriously. I don't know if you've noticed, but we kind of like to learn. Speaking of, let's get on with it. Here's the episode. You're listening to Short Wave from npr. Angela Damas Coraliza grew up in San Sebastian on the northwest side of Puerto Rico. So from childhood, he was used to windy weather, thunderstorms, heavy rain. But nothing really prepared him for Hurricane George in 1998.

[Angel Damas Coraliza]

So in Puerto Rico, we cannot evacuate from hurricanes because we're in an island. So we had to kind of weather the hurricane. So we were up all night. And I just remember the winds roaring and the house shaking. My family had to put these, like, wooden panels to protect the windows and the doors. And I remember, like the wind just hitting those, those doors. And that really left an impression on me.

[Emily Kwong]

That hurricane really etched into his memory.

[Angel Damas Coraliza]

I was 10, so I was a child. I couldn't believe that something so powerful and destructive was in nature's arsenal.

[Emily Kwong]

And this memory became a driving force for Angel's career. He pursued his curiosity about weather all the way to a PhD in atmospheric science and meteorology. He graduated in 2016. And the following year he In 2017, another storm hit, one that changed Puerto Rico forever. And that, Noah said, was the 10th most intense Atlantic hurricane on record.

[Angel Damas Coraliza]

Maria was a life changing experience. Like, I was not able to contact my family for weeks. It was kind of like a grieving moment, like nobody in my immediate family passed away from Maria, but it almost, it was like something died with that storm.

[Emily Kwong]

Angel again felt nature calling him, pushing him.

[Angel Damas Coraliza]

I was already like a dedicated tropical meteorologist trying to understand how humidity, circulation and rain interacted with one another. But I felt like this bigger desire to really want to understand what are the big driving forces? What is it that causes tropical weather to tick? And so I felt this drive to serve my community even more. Like I wanted to be able to go back to Puerto Rico or go to any other community that's in the tropics and be able to tell people like, these are the things that matter. These are the things that drive weather and climate in the tropics. These are the things that you need to pay attention to.

[Emily Kwong]

Angel went on to research tropical weather systems, and he's the person who has really popularized why water vapor in the tropics humidity is such a key player in tropical weather and climate. His work was so notable, it caught the attention of the MacArthur Foundation. Full disclosure, the MacArthur foundation is a financial supporter of NPR. On Wednesday, the MacArthur foundation announced that angel and 21 other people at the cutting edge of their different disciplines had been chosen as recipients of the MacArthur Fellowship, unofficially known as the Genius Grant.

[Angel Damas Coraliza]

I was like, what? And then my brain just completely melted and I don't remember anything else from the call, to be honest with you.

[Emily Kwong]

Angel told us it meant a lot to be chosen to get this kind of recognition and bring it back to the island.

[Angel Damas Coraliza]

You know, coming from Puerto Rico. Puerto Rico is a small island. We do have our contributions to society. We're kind of known for the arts and for like music for example. But we don't often get recognition for science, especially my discipline, you know, like as a community, we've been invisible. And to be able to receive this award where somebody comes out to you, in this case the MacArthur foundation, and they tell me like, no, we see you, you know, and we see what you're doing and we think that what you do matters. It's not just what you're doing, but what your community is doing. To me, this is everything.

[Emily Kwong]

So today on the show, prize worthy knowledge of tropical weather, why the tropics are so different from weather at the poles or the mid latitudes of the globe, and how Angel's work is contributing to make weather forecasts better for everyone. I'm Emily Kwong and you're listening to Shortwave, the Science podcast from NPR.

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[Emily Kwong]

All right, let's talk about the weather and atmospheric science. I know early research into atmospheric dynamics began in the 20th century and it mostly focused on countries in the mid latitudes between the tropics and the poles. In the Northern hemisphere, the mid latitudes cover North America, Europe, a lot of Asia.

[Angel Damas Coraliza]

Yes.

[Emily Kwong]

And in the southern hemisphere, the mid latitude covers what, the bottom of South America, a little bit of Australia.

[Angel Damas Coraliza]

Yeah, it's most of Australia, like a good chunk of Australia, New Zealand, this very southern part of Africa, and kind of like the southern half of South America and almost the entirety of like first world countries in the Northern hemisphere, which is something that is relevant to the research that I do. Okay. The majority of the developed countries, they're used to the stuff that I see here in Madison, Wisconsin, which is like, it gets really cold some days, some days get really warm. Weather is very, very shiny. Temperatures change it very dramatically. It can be really rainy, really dry.

[Emily Kwong]

Got it, yeah. So it sounds like the majority of weather research historically has happened in mid latitude countries, these wealthier countries. And there's been an absence in understanding about tropical weather. What do we know what has been known about tropical systems in the past?

[Angel Damas Coraliza]

So there was a lot of common knowledge. For example, the indigenous populations of the Caribbean knew about hurricanes. So the Taino, for example, they had the semi, which is kind of like their entity of destruction is Huracan. That's where the hurricane name comes from. And so there was knowledge of these things. Right. And then same with the Peruvian natives, they knew about El Nino. So local communities did know about the major phenomenon. Maybe not necessarily what drove them, but they knew about their existence. But of course the mid latitude countries that were actually pushing the research, they didn't really know much. Right. And so there was knowledge in India, China and other communities as well, but there wasn't that much conversation. So it's actually, I don't think it's incorrect to say that people in North America and Europe knew nothing about the tropics until World War II.

[Emily Kwong]

What changed in World War II and what did they figure out?

[Angel Damas Coraliza]

So World War II came and what happened was that the US and the Allied countries got into war with Japan and Japan had taken over a lot of islands in the Pacific. So a lot of the War actually happened in the tropical Pacific. And early combat was actually kind of catastrophic because typhoons, actually a typhoon came and sank a navy ship, for example. Before all this happened, people had just assumed that the tropics were kind of like this paradise. It was just sunny and beautiful all the time. And maybe every now and then you get a hurricane. But then people started realizing, oh, oh dang. Weather in the tropics does actually change at a substantial scale. And this is all summarized in the first tropical meteorology book ever written by, by, by, by somebody in, in the Northern Latitude by Herbert Riel in 19, in the 1950s. So his first paragraph of the book is like, oh, we didn't know that this was serious. And then we realized that it was serious in World War II.

[Emily Kwong]

And in some ways, I suppose you and colleagues like yourself, you are deepening that knowledge. You are figuring out what weather is in the tropics. What do we know so far? How is it different?

[Angel Damas Coraliza]

It's super different. So the first thing that's like, there are some really guiding principles for the mid latitude dynamics that we teach in the classroom. For example, we have this thing, this very important balance that's called geostrophic balance. So it's actually. So if you look at the major weather patterns, you have the jet stream, right?

[Emily Kwong]

The jet stream that is that big current of wind that moves from west to east over the Atlantic.

[Angel Damas Coraliza]

Yeah, yeah. So commercial aircraft take advantage of the jet stream and then they fly along the jet stream to make the flight faster, but then they have to fly against it on the way back. So it is actually slower.

[Sponsor/Advertisement Voice]

Right.

[Angel Damas Coraliza]

So we know that these currents exist and they're actually in a very, very elegant balance. The waves want to accelerate to the poles, but then the coriolis force, which is the bending effect that you get from the planet being in rotation, it bends it the other way. So it causes all the combination of these forces creates the jet stream. And the jet stream goes from west to east and in this jet you get these waves, so you get these undulations. And these undulations are the troughs and ridges that create our day to day pattern. So that's why temperature fluctuates a lot. The cold war side of the jet is really cold. The equator one is warm and, and the jet is waving all the time. So you just get days that are warm and then they start cold in alternation.

[Emily Kwong]

Oh, so that explains the mid latitude variability.

[Angel Damas Coraliza]

Right, right.

[Emily Kwong]

But the tropics is not like this.

[Angel Damas Coraliza]

It is not like this at all. So the Tropics are pretty warm year round, so you don't really see the temperature variability that you see here in the mid latitude. So things like cold fronts and stuff that barely exists in the tropics, you don't really worry about that, but yet you still get these periods where it's really, really rainy and with dry periods. So instead of thinking about temperature variability, it gets really cold or it get hot in the tropics it actually gets really humid or it's really dry. That's really kind of the big thing that drives weather patterns.

[Emily Kwong]

So you're saying in the tropics it's all about the moisture.

[Angel Damas Coraliza]

It is about the moisture. Yeah, yeah. There's other things that matter too, right? Because it's always more complicated than that. But if you want, if I go to a classroom and I teach people, what are the things about the tropics that make the tropics different? That's going to be one of the things that I'm going to mention. Probably the thing that I'm going to.

[Emily Kwong]

Mention in light of the fact that the tropics are so different from the mid latitudes. What's surprising to me and I. You said this elsewhere in some of your work is that there's no. For, for a few years there, there was no textbook on tropical atmospheric dynamics. There kind of wasn't like a comprehensive theory of the tropics. How did that affect weather forecasting in the tropics?

[Angel Damas Coraliza]

So I don't think we still have a comprehensive theory of the tropics, at least when you compare it to the mid latitudes where we have multiple textbooks, we have mature theory. The vast majority of weather forecasting models were initially built to tackle mid latitude weather, not tropical weather. And as a result forecasting weather and climate events in the tropics is more daunting to the detriment of the people that live there. Right. Because sometimes you do get extreme events like floods, heat waves and things that actually are very costly, not just in infrastructure but in life and they're not very well predicted, you know, and so that's the big thing, right? Like ultimately it is a problem of human safety and well being that we cannot forecast things in the tropics as well as we do in the mid latitudes.

[Emily Kwong]

Got it. Okay. Well in pursuit of a comprehensive dynamical theory of the tropics, you have studied many things and one of the earliest things you focus on was something called the Madden Julian Oscillation or mjo, which is this large region of thunderstorm activity in the Tropics.

[Angel Damas Coraliza]

Right. So the MJO is actually the most important tropical phenomenon that you don't know, that people don't know about. That's the way that I would like people to think about, is comparably as important as El Nino.

[Emily Kwong]

Really? The mjo?

[Angel Damas Coraliza]

Yeah.

[Emily Kwong]

Okay.

[Angel Damas Coraliza]

And it has not just massive impacts in the tropics, but it has impacts throughout the globe. It actually modulates weather in the mid latitude. For example, at Masuric. Rivers that cause flooding in California are modulated by the mjo. So it's a global phenomenon. It's rooted in the tropics. It starts in the Indian Ocean. It is about the size of Russia, so it's huge. And it propagates eastward pretty slowly. And in that movement it modulates hurricane activity. So when the MGO is active, hurricane activity increases.

[Emily Kwong]

Fascinating.

[Angel Damas Coraliza]

And so forth.

[Emily Kwong]

So you started studying the mjo. What did you find and what does the MJO tell us about the tropics as a whole?

[Angel Damas Coraliza]

When I started studying it, I started kind of learning about the importance of water vapor in tropical rainfall. And then after that, I started realizing how all these insights about the MGO translate to all sorts of other tropical phenomenon. For example, when it's humid, it starts to rain, but then all that rain actually changes the wind patterns. And the wind patterns then change in such a way that the movement, that moisture gets moved around and so the moisture gets moved around and so the rain moves with the moisture. So all these three things get coupled together. The moisture, the rains and the winds, they couple together.

[Emily Kwong]

They're playing off each other.

[Angel Damas Coraliza]

Yeah, they play off each other, so they feed back on each other. And so that causes the MGO to move, you know, according to the theory that was being proposed at the time, which I contributed to. And so I was like, what if other tropical weather phenomenon work the same way? Right.

[Emily Kwong]

With the idea being that these winds move the humidity, the rain changes the wind patterns, and it becomes this recurring feedback loop of weather. Cool. Well, I have one last question for you about tropical weather. You are obviously not alone in studying it. There are a lot of other atmospheric scientists who study the tropics and who are pushing for a greater global understanding of this area of this region. What future are you all trying to build?

[Angel Damas Coraliza]

I would like to see a role in which when we're making climate reports and when we're making forecasts, that everybody is being equally represented and that everybody's being done justice. Because at the end of the day, everybody deserves to have the best possible weather forecast. Everybody deserves to know to the best degree possible what's going to happen in the climate in the region right now. And right now we don't, we don't equally have the knowledge about climate and the atmosphere for everywhere. I think that speaks volumes to where we are right now. And where we should be is a place where everybody knows the same amount about everywhere.

[Emily Kwong]

Angel, thank you so much for coming on Short Wave. And congratulations again. Thank you on your grant.

[Angel Damas Coraliza]

Thank you so much.

[Emily Kwong]

This episode was produced by Hanna Chin and edited by our showrunner, Rebecca Ramirez. It was fact checked by Tyler Jones. Robert Rodriguez was the audio engineer. Beth Donovan is our senior director of podcasting strategy. I'm Emily Kwong. Thank you for listening to shortwave from npr.

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