- 7/16/2025
Dr. Marshall Shepherd, meteorologist and Forbes senior contributor, joined "Forbes Newsroom" to discuss recent historic flooding in New York City and New Jersey, as well as the devastating flash flooding in central Texas earlier this month.
Category
🗞
NewsTranscript
00:00Hi everybody, I'm Brittany Lewis, a breaking news reporter here at Forbes.
00:07Joining me now is meteorologist and Forbes senior contributor, Dr. Marshall Shepard.
00:11Dr. Shepard, thank you so much for joining me once again.
00:14Thanks for having me once again, Brittany.
00:15The Big Apple and the Garden State saw record-breaking rainfall a little over rush hour on Monday night.
00:22New York City saw the second most rainfall in an hour ever recorded in its history,
00:27and New Jersey Governor Phil Murphy declared a state of emergency.
00:31So to start off the conversation, how exactly did this happen?
00:35You know, it was a perfect convergence meteorologically speaking.
00:39There was plenty of moisture in the atmosphere.
00:44There were sea breeze fronts and prefrontal troughs and outflow boundaries from early morning convection.
00:51All of these things came together, unfortunately, at a really tough time of the day.
00:57All of that moisture was lifted violently, and we saw extreme rainfall rates.
01:02And that really is the story, Brittany.
01:04Hopefully we can talk about it.
01:06How much rain is falling so quickly from these storms?
01:10And I want to dive into exactly that because I work in New Jersey.
01:14I work right across the river, so I have a perfect view of the Manhattan skyline.
01:19And I was just in the studio around rush hour on Monday night, and I got a few texts saying,
01:25hey, be careful when you come home from work.
01:27I was like, really, what are you talking about?
01:28I brought my umbrella to work that day, but I go out, and the sky's pitch black.
01:33I mean, it looked really sinister out.
01:35I got drenched going home, but I was lucky.
01:37My subway wasn't one of the cars that was shut down.
01:40But what you saw from videos on social media was really apocalyptic in New York City in that hour.
01:47I mean, trains were flooded.
01:49There was a conductor saying, it's unsafe for me to open the doors right now.
01:52I mean, it looked like a scene from the Titanic.
01:54So how did it fall so fast?
01:57Yeah, it reminded me of what happened in New York after the remnants of Hurricane Ida a few years ago,
02:02a similar sort of flooding in the subways and so forth.
02:04Again, there was so much moisture.
02:07There was quite a bit of lift in the atmosphere as you had a frontal system and a prefrontal trough
02:14that was approaching from the west.
02:16That's probably what you saw as the sky was.
02:18You probably saw the clouds building as that system was moving in.
02:23But, Brittany, we've seen flooding throughout the U.S. this year.
02:28One of the things that we see as we've seen this flooding is there's so much moisture.
02:33There's something that meteorologists look at called precipitable water, Brittany.
02:36It's if you take an imaginary column in the atmosphere and wring out all of the water vapor
02:41and what would be at the ground, we measure that.
02:46And we have seen tremendously high values of precipitable water, which means that if a storm
02:52gets going, it's going to produce rainfall rates like you saw.
02:56Two to four inches of rain in an hour, these are just unbelievable rain rates.
03:03And so it's something that we all just in climate scientists are concerned about because it's
03:07something we've actually expected for many years to come.
03:10And as you said, the only other hour in New York's history was that saw more rainfall
03:17was during Hurricane Ida back in 2021.
03:19This wasn't a hurricane.
03:21This was just a summer night with some rain.
03:24I mean, is that worrying to you?
03:25It is worrying because, again, as our atmosphere warms, look, we get storms naturally in the
03:32summertime.
03:33We have rainstorms.
03:34What we're seeing increasingly, Brittany, in the scientific studies and literature is that
03:38when it's raining, the top one, two percent events are raining with more intensity than
03:43they were two or three decades ago.
03:45That means more rain is falling over shorter periods of time.
03:48Why that's of concern to places like New Jersey and New York is not only is it raining with
03:54greater intensity, you have all of that impervious surfaces, pavement, parking lots, and so forth.
04:00So that rain doesn't have anywhere to infiltrate into the soil, so it runs off quickly into streams
04:05and lakes and rivers, and they fill up quickly.
04:07So that water cycle that we learned about in fourth grade, that wasn't a realistic water cycle.
04:13It didn't have paved surfaces and parking lots and things like that.
04:16An urbanized water cycle will have much more runoff, which will exacerbate the flooding
04:21from these more intense rainstorms.
04:24And I want to read a quote from a piece that you wrote for Forbes regarding this storm.
04:28This is what you said.
04:29It was a somewhat typical scenario with an optimal alignment of ingredients.
04:33However, there is a climate backdrop that must be discussed.
04:37Can you talk about that climate backdrop for us?
04:40Yeah, you know, as a climate scientist, people often say,
04:42well, Dr. Shepard, these things happen naturally.
04:44We get rainstorms in the summer.
04:46It's just summer rainstorms.
04:47Well, yes, we do get storms naturally, but it's not either or, Brittany.
04:53It's and.
04:54We have these naturally occurring rainstorms, but there are some basic physics that explains
04:58some of the things that I think we're seeing.
05:01As the atmosphere warms, it has more water vapor capacity.
05:04There's more water vapor available from evaporating streams and lakes and oceans and so forth.
05:09So there's more water vapor available to these afternoon thunderstorms to be converted to
05:14rainfall.
05:15And then secondly, Brittany, and I think it was part of the story.
05:18If you look at the ocean temperatures off the east coast of the U.S. and the Gulf temperatures
05:23down down here where we are, they're quite warm.
05:27And so when they are that warm, there's greater evaporation of water vapor from the ocean to the
05:31atmosphere.
05:32And so that just provides additional moisture for these storms.
05:37And so I think we're seeing a convergence of things that are both weather and the impacts
05:43of a warming climate as well.
05:45I think that's an interesting point and kind of something to say to the naysayers or people
05:50in the comments that say, hey, this is a typical thing that we see rainfall in the summer.
05:55I mean, that's not exactly new.
05:56And you're saying, yes, this is a summer storm and so what is this indicative then?
06:03What is that and that we could potentially see this summer and beyond?
06:07Yeah, it's bizarre to me that people tell me as an expert on weather and climate that
06:11this is natural.
06:12I promised them that I didn't miss that in all of my years of study at Florida State University.
06:17We know that storms happen naturally.
06:18We know that thunderstorms pop up naturally in the summertime.
06:21But the important thing to note is it's not natural or climate.
06:28There's a mixture likely of both these days.
06:30So, yeah, you probably would have gotten a flood in producing storm given that setup conditions
06:3650 years ago also.
06:39But what's different, Brittany, is that the ocean temperatures are much warmer on average
06:44this time of year and there's more water vapor capacity in the atmosphere.
06:47So, that just makes these storms that much more prime.
06:51And I'll throw one more thing in.
06:53The stormwater removal, the engineered systems in our cities were designed under an assumption
07:00of stationarity, which means they were designed assuming that a rainstorm in New York in 1970
07:06would look just like it does in 2025.
07:08But we know that they don't.
07:10They have chains.
07:11So, we've got to catch up with the stormwater engineering assumptions as well.
07:14And this was especially alarming because it came off of the heels of a really devastating
07:19flash flooding incident in Central Texas earlier this month.
07:24Over 130 people died.
07:26As a result, there are still many missing.
07:29Was this storm that we saw in the Northeast, in New Jersey and New York, related at all to
07:33the Texas Hill Country storm?
07:35No, those are different weather systems.
07:39But what they both had in common is that there was so much moisture in the atmosphere, different
07:46source.
07:47A lot of that moisture was coming from the Gulf, whereas I think a lot of the moisture, some
07:51of it was likely with the Gulf with this New York storm as well, New York, New Jersey storm
07:55as well.
07:55But there was also quite a bit of rich moisture out along the Atlantic seaboard as well.
08:00So, yeah, different systems, but I think they both had in common extreme levels of moisture.
08:06What I will say about the Texas floods, which I was hearing, there were rumors and innuendo
08:10out there about cloud seeding and all kinds of things out there.
08:15Cloud seeding doesn't cause these types of extreme rainfall events.
08:18In fact, what we know from the scientific literature is that cloud seeding is inconclusive
08:23as best.
08:23Now, you'll have a lot of people out there peddling all kinds of things.
08:26But cloud seeding cannot really affect these types of storms in that way.
08:32And even to back that up a step further, because if you go down any rabbit hole on social media
08:37regarding any weather incident, you're probably going to hear the term cloud seeding.
08:42So explain it to us like we are first graders.
08:45What exactly is cloud seeding?
08:47And why do you think or how did it gain this popularity amongst people who are trying to
08:53peddle some sort of misinformation or a possible conspiracy?
08:56Well, I think first graders probably understand it better than some of what I see in social
09:00media, to be honest with you.
09:02But, Brittany, what we know is that all rainstorms here in the U.S., for the most part, they all
09:07rain.
09:07Even if it's the middle of the summer, it started out as ice in the clouds, believe it or not.
09:11That's hard for people to grasp sometimes.
09:13But even on a hot summer day in New York, 95 degrees at the surface, the ice crystals
09:19in the tops of those clouds started out as, you know, in a frozen form.
09:23So what we know is that in order for those ice crystals to form in thunderstorms or in
09:28rain clouds, they have to have a seed, Brittany.
09:30They need a little nucleus.
09:32We call them ice nuclei.
09:33And that can be kaolin, dust, clay, pollen, things of that nature.
09:39What cloud seeding tries to do, and there have been studies for clouded seeding for many
09:44decades, it tries to stimulate or introduce more of those ice nuclei into the clouds to
09:50get the ice crystals to start forming more efficiently.
09:53But what many of the studies have shown, Brittany, is that most of the storm clouds that get seeded
09:59probably already had enough moisture and seeds in them anyhow.
10:03So I'm going to give you a little analogy that maybe will set this to rest.
10:06Think of cloud seeding as a match, like if you're striking a match, right?
10:12And if you try to strike a match and light a rock, you're probably not going to set that
10:17rock on fire.
10:17There's no moisture there.
10:19On the other hand, let's think of a situation like we had with the Texas floods or even the
10:24New York, New Jersey floods.
10:25There was so much moisture in the air that that cloud seeding doesn't really matter.
10:29It's like striking a match and putting it in the midst of a raging inferno.
10:34So it's not going to really matter because that inferno is has enough juice on its own.
10:39Well, thank you for putting that to rest.
10:41And another thing that we saw in Texas was that the warning systems, people were saying,
10:48hey, I was not adequately warned about just how dangerous this was.
10:52I was out for a walk and suddenly the flash flooding began.
10:55You raised a good point in a Forbes piece.
10:59Would Cat5 messaging change anything?
11:02Do you think there needs to be different warning for these types of flash flood incidents for
11:06people to really, you know, heed those warnings and take concern and understand the impact
11:12of just how dangerous this could be?
11:13Well, first of all, the weather warnings are absolutely there with the Texas floods.
11:19I mean, I documented in a Forbes piece that there were warnings in the days leading up to
11:24this and even in the hours beforehand.
11:26So I think the real issue with the Texas flooding was more in the lack of warning systems.
11:31Candidly, some of those camps and RV parks being located in flood zones from the start.
11:38However, I did raise the point, you know, I think people pay attention when you tell them
11:43there's a Category 4, Category 5 hurricane out there.
11:46And so my point that I was raising is that though we had adequate weather warnings for
11:50people to make decisions with that Texas flooding, would people have made different decisions?
11:56Would they have evacuated those camps a day or two or three earlier?
11:59Have we said there's a Category 5 flood possible in two days?
12:04Because I think people, there tends to be a normalcy bias when it comes to things like
12:08floods and heat, which, by the way, kill more people in the United States every year than
12:12any other weather, just heat and flooding.
12:14But people tend to react more to tornadoes and hurricanes.
12:17And so, you know, there's a experimental flash flood severity index that former colleagues
12:23of mine have developed that's out there that's being evaluated by the National Weather Service
12:27that hasn't really taken hold yet.
12:29So it just makes me sort of ponder, you know, how do we kind of improve the sort of communication
12:36and reception of these types of warnings?
12:39Because people just tend to say, well, I get flood warnings on my phone all the time.
12:43What makes this one different?
12:45I think that's a really good point.
12:47And what we saw in Texas was absolutely heartbreaking.
12:49It was devastating.
12:51It was historic.
12:52Something on Monday night that we saw in New York and New Jersey, that was historic rainfall
12:57too.
12:58Do you think we are in, for the rest of the summer at least, is it going to be this really
13:02wet, dangerous summer?
13:05So this is, we've had, I saw a statistic yesterday in some media outlet that said that we've experienced
13:10more flash flood watches this year than last year and in previous years.
13:15I think that, you know, as warm as the Atlantic, Western Atlantic Ocean and the Gulf are, I think
13:24that there's plenty of moisture available for these storms.
13:28But I think it's a signal, you know, Brittany, if you go back and look at things I wrote 10
13:33years ago, if you look at things in the scientific literature 30 years ago, scientists, climate
13:38scientists were warning about something called an accelerated water cycle, which means that
13:43as our system warms, there'll be more water vapor in the atmosphere on average, and that's
13:49going to prime the pump for more intense rainstorms.
13:52So we don't need some kind of wacky conspiracy theory to explain what's going on.
13:56And the science has long warned of this.
13:59Well, I appreciate the conversation.
14:01I always appreciate your expertise here.
14:04And I always wish that we could speak on better circumstances.
14:07But thank you so much for joining me.
14:09And I hope as more storms continue, I hope that you can come back on and break them down
14:14and make us and help us make sense of them.
14:17Dr. Marshall Shepard, thank you for the time.
14:19Thank you, Brittany.
Recommended
1:12
|
Up next
1:10
0:42
0:13
3:43
7:32