Monsoons

Where Two Deserts Meet

In this episode of Where Two Deserts Meet, we meet up with National Weather Service Meteorologist, Jessica Leffel, and explore the complexities of the monsoon season and what visitors should expect during this time of year when visiting Joshua Tree National Park. We also catch up with Alex Snay, Joshua Tree National Park’s Facility Manager to learn about the importance of safety during flash floods and why we say, “Turn Around, Don’t Drown.”

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TRANSCRIPT:

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Donovan: Where two Deserts Meet is an official podcast of Joshua Tree National Park. Joshua Tree National Park acknowledges the Serrano, Chauilla, Mojave, and Chemehuevi people as the original stewards of the land in which the park now sits. We are grateful to have the opportunity to work with the indigenous people in this place, and we pay our respects to the people past, present, and emerging who have been here since time in Memorial. Ian: Hi, I'm Ian. Donovan: And I'm Donovan. Ian: And we are both park rangers here at Joshua Tree National Park, Where Two Deserts Meet is an official podcast of Joshua Tree National Park, where we explore topics that often require a bit more detail and the help of an expert in the field to gain perspective. Donovan: Hey, Ian, did I ever tell you about that one time I almost got caught in a flash flood? Ian: Uh, no. What happened? Donovan: During the summer of 2022, I was stationed down at Cottonwood Visitor Center for the day, and the drive down was pretty peaceful and covered with blue skies. As the day went on, I remember often looking outside the west facing window and I started to see denser and denser clouds form. I remember actually being pretty excited by this image because usually that means that the sun will be blocked by them. Providing a brief moment of shade, which can feel amazing, especially when it's usually over a hundred degrees Fahrenheit outside. That feeling of relief was short-lived. However, as those white fluffy clouds soon turned to a dark gray cover, blocking all sunlight completely, what once was a pleasant Sunday afternoon? Looked as though it was now. 8:00 PM at night. It was clear to me that the rain was coming and I needed to get back as soon as possible. Luckily, we had just closed up the visitor center and we were getting ready to drive back up to headquarters. As we started to drive, we heard sounds of thunder in the distance. We could see some signs of rain about five to six miles east of smoke tree wash just off of Pinto Basin Road there. But luckily, no signs on the road. We were actively driving as we turned the corner. Suddenly we started to see a small stream form across the porcupine wash area. The water was only about one to two inches deep, so I decided to push forward. I then pulled over and waited just to keep an eye on the situation, but not even after one minute of driving through what was a small creek, it had now become a river at least. Four to five inches deep. I got out of the car and put on a safety vest to stop incoming cars from passing through the flood. After about five minutes, the water was almost a foot deep and I could see large rocks in boulders being pushed onto the road by the force of the water. I radioed the rest of the park to let them know that there was a flash flood occurring. The amazing part about all of this that I'm still surprised today about flash flooding is for myself and those cars that had to wait that day, we only waited about 20 minutes for that water to come and go. As fast as it came, it went and everybody was able to proceed on with a regular day, you know? Ian: I feel like that's actually sort of a common story. Most rangers at Joshua Tree National Park have had their own flash flood story after living here for a while. Your story reminds me of how hard it is sometimes as a ranger giving informed advice to visitors, considering sometimes we get those visitors who really want a definitive answer on if rain will impact their trip or not. Sometimes the only thing we can advise them is to be prepared for anything, especially during the monsoon season when it's hot and summery and rain is the last thing most visitors expect. But the monsoon season here has played a significant role in shaping the desert. Donovan: I feel like the weather here in the desert often confuses a lot of people. The extremes of day and night temperatures elevated precipitation in the summer. I think it's about time we consult a meteorologist on this one. Ian: Wait. What do meteors have to do with weather? Dononvan: Oh, okay. Ian, you know what meteorology is. Ian: I know. I just couldn't let us get away with doing a meteorology episode without making the joke once. But really though meteorology is no joke despite its misleading name. Meteorology goes beyond just the study of weather. The atmosphere and its phenomena. Donovan: And of course when talking about meteorology and Joshua Tree National Park, it would be impossible to do so without mentioning our friends at the National Weather Service in Phoenix, Arizona, who we rely on daily to have the most up-to-date weather inside the park. Luckily, a meteorologist at the National Weather Service agreed to talk with us on all things weather and especially the complexities of the monsoon season here in Joshua Tree National Park. Jessica: My name is Jessica Leffel and I'm a meteorologist at Nashville Weather Service Phoenix. Uh, we have over 120 different weather forecast offices across the country, and they stretch anywhere from Puerto Rico to Guam, but here in Phoenix, we actually cover South Central Arizona, stretching all the way into Southeast California. And we do a variety of different things here. So we'll do anything from forecasting to aviation weather to DSS, which is decision support services, helping our political partners out if they have events going on, as well as looking out and doing outreach events too, and doing the best that we can to get out into the public and educate people on weather preparedness. Donovan: On top of all that, Jessica is a part of the team that plays the important role of providing the weather forecast for Joshua Tree National Park. We utilize their weather resources in all our daily operations, visitor education and resource management. In the desert where weather conditions are often extreme, receiving alerts of potential hazardous conditions is often critical to visitor and park staff safety. But before we dive into that, we ask Jessica, what does an average workday look like for a meteorologist? Jessica: Depending on the day, you know, usually right now we're starting to get into the monsoon, so, our shifts will be a little bit more occupied. But outside of that, we do have routine shift duties that we have to get accomplished. So that's putting out our forecast. So that's something that anyone could go on our website to see what the high and low temperature's going to be, what the winds are going to be like, or all of those different. Variables that they're interested to know about the weather. We also put out a forecast discussion as well, and that kind of covers goes over our understanding of what's happening in the upper air and giving a better idea of synoptically what's happening so we can explain our reasoning and what different things we're seeing to cause the current weather that we're having. On top of that as well, we'll also put out an aviation forecast and that will include things called T A Fs. TAFs for short, and it's a terminal arid drum forecast. So this is something that we provide for the different airports within our region. So we have, currently about five airports that we create these forecasts for. And they'll go over any conditions or any changes so that the airports are ready to go and know if they need to change their runway configuration, if there's gonna be a wind shift, for example. Um, just to increase the safeness of the taking off and landing of airplanes. Beyond that as well, we do answer lots of public phone calls anytime anyone has any question about what's going on with the weather, as well as answering phone calls from our media partners to produce interviews to give, the public a better idea of what's happening and what different things that they can be prepared about for upcoming weather. And then beyond that, whenever we get into the actual activeness of the monsoon and the height of everything, we'll start putting out watches and warnings and advisories and doing the best that we can to warm the public before severe weather is approaching Ian: Meteorologist do a lot more work behind the scenes to keep us safe than we can even imagine. However, we often take weather forecasts for granted as they are often much more work to produce than it takes to access them. It's easy for us as the general public to open up an app on our phone and within seconds get an idea of what the next seven days of weather will look like almost anywhere in the world for a meteorologist. It's much more than that. So what exactly is happening behind the scenes of those forecasts? Jessica: With weather prediction, we do a lot to look at the current state of the atmosphere, and then we also look at a bunch of different models and different things to see how the atmosphere is going to evolve and then change our forecast. So we'll look at lots of current observations. So we'll check out what's happening with surface observations, what's happening with satellite imagery, what's happening with radar data radio, saw data, upper air data, and much more to get a big picture idea of what's currently happening. And then we use our pattern recognition and the skills that we learned in school from our foundation of understanding the upper air and the atmosphere and the different changes that it goes through, depending on the atmospheric pattern, we're able to see how this situation currently is going to evolve, and then that helps us predict whether and then make our forecast. Donovan: So there's surface observation, satellite observations, radar data, and more. There are so many complex resources and factors that go into the forecast that we receive. This reminds me of a common visitor question I get, which is, I'm camping in Joshua Tree National Park about two to three months from now, what will the weather be and what can I expect? And honestly, us rangers can give you an estimate based on past weather averages in the park, but to provide specific details that far in advance is quite complicated. Jessica: We produce a seven day forecast. Obviously, the closer it is in time, the more accurate that it will be. Just because we're able to get a better idea of what's happening currently and from day to day, we're able to see that variation in those small minute details and understand what's gonna happen a little bit better. However, as we get further on the forecast, things can definitely change. That isn't to say that long lead forecasts are not accurate. We do have, you know, a climate prediction center that will put out three month outlooks and things of that nature that can be fairly accurate. But as we get closer, we're able to see what those local influences will be a bit better. So for example, with this current monsoon and the climate prediction center was forecasting above normal temperatures and below normal precipitation for much of our region and our office. So with that, we were able to get a better idea of what we were going into, but as it's gotten closer, we were able to see how things have evolved, how it's changed, and create a more. Specific forecast that's more detailed with the current observations that we have now to better formulate our, our forecast. But closer it is the more accurate it is. But the reason that we do seven days out is because those are our, our highest confidence intervals. If we started doing eight days and beyond, then we would have more uncertainty in the forecast and there would be more changes. So we feel very confident with our seven day forecast. So that's why we release those to the public. Ian: Some confidence is very important when predicting precipitation in the desert, and we know precipitation isn't always the first thing that comes to mind in the desert, but why is that? What causes some landscapes to get large amounts and others to get maybe just a few inches a year? Jessica: A desert basically just lacks the available moisture to pull from in order to produce precipitation. So that could be due to a variety of different factors, whether that's the atmospheric circulation pattern, and you're over a high pressure system, which is usually in tuned with hot and dry conditions, or if it's the prevailing wind pattern that is. Producing an effect or topographic barriers and terrain influences or different temperature variations. So there's many different factors that can cause a desert to not receive as much rainfall as exterior regions that might receive more. So Joshua Tree National Park is under the influence of what's called the rain shadow effect, and this is essentially just the absence of rain on the leeward side of the mountain. So with that as air cools, as well as climbs over a mountain range, it begins to dry. So because we've got Mount San Jacinto as well as Mount San Gorgonio, just west of Joshua Tree National Park, as this air moves in, it is then pushed up by these mountains, and then it cools and dries as it rises over the mountains. So then, Only the mountains are really receiving that precipitation. And by the time that it reaches over the mountains and gets to the leeward side of the mountain, it doesn't have any moisture left to pull from. So the water vapor content is significantly decreased, and then we can't get as much rain in Joshua retrieve because of those mountains just west. Donovan: So when visiting Joshua Tree National Park and traveling from places like Coastal California, you may get a glimpse of two large and often snow capped mountains just west of the park. The leftover rain from those storms that hits those mountains often isn't much. For example, big Bear Lake located at the top of San Gregorio gets about 70 to 80 inches of combined snow and rain every year. Whereas Joshua Tree National Park only gets about four to seven combined inches annually. This is a huge difference when you consider that these landscapes are only a handful of miles apart. This doesn't mean that the rain can't catch people off guard here, though. Ian: Yeah. No matter how much precipitation a place gets annually, it's always important to plan ahead and check the weather. But interpreting the forecast is also important. Like the whole probability of precipitation can be a little confusing. Like what exactly does 20% chance of rain mean? Luckily we have Jessica. To clear things up. Jessica: Yeah. So whenever we're giving probabilities and different percentages of what's happening with rain coverage, um, just know that that is for aerial coverage. So if it says 20% chance for Joshua Tree National Park, it's for the region. It's not necessarily saying that there's only a 20% chance of rainfall in one specific location. So you have to kind of take it with a grain of salt and understand where that probability is coming from in order to better have a better idea if you're gonna need to bring an umbrella or not, for example. Donovan: Being prepared for a potential thunderstorm can make a huge difference in the success of your trip. Summer is the most common time of year. People don't expect rain in the park, but those who live locally often, once summer comes along, it's on everybody's mind. The monsoon season is why Joshua Tree National Park often gets a majority of its rain during the summer months, but what exactly is the monsoon season and what can visitors expect from the weather during this time of year? Jessica: What will happen during the monsoon is our high-pressure systems will relocate themselves to create a more favorable pattern for thunderstorm development. So what happens there is by late spring, heading into early summer, we start to see strong solar heating take place, which causes hotter temperatures, and then our surface air pressure starts to decline. And then this formulates what's called a thermal low. From there on the difference in surface air pressure starts to cause the air over the ocean, which is more moist in nature and cool to be pushed into these hotter and dry regions. And as that air pushes in, it also brings instability with it, causing these sun to develop and the three main ingredients that you need for thunderstorm development, our moisture, instability, and uplift. So as that moisture comes in, we're able to get those thunderstorms develop. And because there's currently thunderstorms happening, It increases the humidity in that region, so more thunderstorms are able to take place. Um, and then from there we also have the unstable air. And then we're seeing, uh, as I was mentioning, those uplift is another ingredient that we need. So that's why we usually see our monsoon thunderstorms will actually start over our higher terrain features first. So any mountain ranges. Will get that precipitation to start there first, and those storms will start there and only if they're strong enough will they make their way to lower elevations. And it's just because the uplift mechanisms that are reintroduced with those higher terrain features allows air to push upward, and then the instability works along with the moisture to create those storms. So usually as we start to move into those lower elevations, we're losing out on that uplift mechanism that helps create those thunderstorms. And it's why it's only those stronger thunderstorms that are actually able to make it to lower desert areas. But beyond that, once this occurs and rain falls, you know, we're able to have this loop where we have continual moisture and that. Whole season is able to continue and continue having thunderstorms because that available moisture is there to pull from and then it doesn't actually decrease and fizzle out until surface temperatures start to decline. And then from there, there's not so much of a difference between our surface air pressure and there's no longer this competing force there. Ian: As Jessica mentioned, those monsoonal storms often form around high geographical features for Joshua Tree National Park. The two most prominent peaks to find a storm forming around are Queen Mountain, just north of Skull Rock and Pinto Mountain, just east of the Choa Cactus Garden. Once that moisture cycle starts, those storms can rapidly form over the next few days, all throughout the park. Donovan: We often get visitors who are from other areas where monsoon storms don't regularly occur and often mistaken them for something like a tropical storm or cyclone, thinking that they are similar, but although similar in appearance, they aren't the same thing. Jessica: Yeah, so a monsoon is a season, as you mentioned, so it is a calendar based definition of June 15th through September 30th. Um, that doesn't mean that monsoon thunderstorms can only occur during this timeframe. It's just when we commonly see them and when we have usually the pattern developed for those favorable thunderstorm conditions in the upper air. However, you can definitely get those thunderstorm patterns outside of that as well. So a monsoon is a. Season, it's something that will occur over an extended period of time and over a larger region as well. So, for example, we are under the influence of the North American monsoon. So this is a, you know, continental pattern that happens, whereas a tropical cyclone is a more individual in nature storm. So you can have multiple tropical cyclones happening at once or just an individual one. But with that it's individual in nature. It's moved by specific high and low pressure systems competing, and it's more of a frontal boundary or things that are happening there that are causing it, rather than the overall pattern allowing for this favorable condition to happen for months on end. So a tropical storm instead is, Just a strong rotating calm of air, usually centered by a low pressure, and it's, got a closed, low level circulation that's able to produce those very strong winds and heavy rains and squall lines and things of that nature rather than the monsoon itself, which is a full on season and has these conditions for an extended period of time. Ian: So to put it in a way that hopefully makes it easier to remember, the monsoon is an entire season of atmospheric changes. Unlike tropical cyclones which operate individually, one thing they do have in common, Is rain and lots of it. A monsoonal storm can cause a rapid downpour of precipitation to concentrated areas causing something called flash flooding. But why do flash floods more commonly occur in the desert compared to other regions? Jessica: So we get more flash floods during the monsoon because we have longer duration precipitation events. And with that as well, our region and our soil content isn't able to necessarily take in moisture as well as other regions might be. Also, it has to do with our infrastructure and the way that roads are built in and the way that things are built over the years and how we have different regions where we have lower elevations and these low water crossings that as rain falls and pools, it obviously has its runoff pattern and finds the lowest spot possible to continue its path and it. Finds those lower spots and, and reaches into them and fills those regions very quickly. So anywhere where we have maybe a road that maybe should have been a bridge or um, has a dip in the road there, um, is more susceptible for water to pool there. So it's just those low water crossings, those lower lying areas where water will then accumulate very quickly. Um, and then from there, flash floods are just more common during them monsoon because we get heavier rainfall at that time and for more longer durations as well. Donovan: As Jessica mentioned, rain will often find the path of least resistance, allowing it to collect in runoff areas, which often compose a huge risk to our safety. Jessica: Yeah, so flash loads are extremely dangerous. It only takes six inches of moving water to knock over an adult and then 12 inches for, um, small cars to be moved away as well. And then we get up to 18 to 24 inches, can actually push away a large SUV or trucks. So it's really not that much moving water that can get things to start pushing and moving. Um, and with that as well, flash flooding is, Very dangerous and, and causes a lot of different drowning events, so people might not think, oh, this low water crossing here, I'm seeing some flooding happening and think, well, I'm in my truck. I'll be fine. I can go ahead and drive through this. That's the most dangerous thing that you can do in that case. So if you come across a area where there is flooding, never drive through the water, you definitely wanna turn around because people often underestimate the power of water and power of moving water and how strong it could be. So you might face a situation where you're now stuck and you can't swim your way out because the current is just. Too strong and your vehicle is now not even attached to the ground anymore. It's now hydroplaning completely, and you just have no way to get out besides getting rescued. So it can be very dangerous and it can get very dangerous quickly, um, as flood waters escalate very fast. Donovan: According to the National Weather Services website in 2022, there were 102 fatalities caused by flooding and 146 in 2021. As Jessica mentioned, it does not take a lot of water to sweep you off your feet. Six inches to knock over an adult. 12 inches to move a small car and only 18 to 20 inches can move a large truck. When these floods occur, they're not only rapid in their appearance, but fast moving with great force. Ian: Unfortunately, flash floods are not the only safety risk when it comes to monso storms. There's also lightning, that loud flash of light coming from a storm cloud, often causing destruction to whatever it encounters. What lightning is, in simple terms, is an electrical discharge caused by the splitting of atoms, often moving across the sky in the path of least resistance. As its energy is released, it can be extremely dangerous to be caught in its path, although you have less of a chance of being struck by lightning compared to being caught in a flash flood. It's still important to be prepared and know what to do in case of a lightning strike. Jessica: So lightning is very commonly associated with storms. With that. We can even receive dry lightning when we might have a storm that doesn't have much precipitation with that, and lightning is incredibly dangerous. People often underestimate the power of lightning and think, I'll never get struck by lightning. That's incredibly rare. While it is rare, the cases have risen each year in the United States, so it's important that we're prepared and know what safety procedures we can follow whenever we see a storm coming, in case that is accompanied by lightning. One of our favorite sayings to say around here is when thunder roars go indoors. So anytime you hear thunder, go ahead and go do what you can to get inside. If you're already in the park, go ahead and hop into your car. It's also safe to be in a metal hard topped vehicle because if lightning were to hit your car, it would actually go around the exterior of your vehicle rather than ate you as you're inside. Also wanna say, make sure you're seeking shelter, not in something. That would be an open building or open feature. So if you're under something that looks similar to a bus stop, for example, where it's open and doesn't have closed features that would not be considered safe. So do what you can to get into a closed vehicle . If you can get into a building, that'd be great. If there's a visitor center nearby, run in there. That would be the most safe location. And also wait until 30 minutes after you last your thunder to go back outside and resume your outdoor activities. Donovan: When thunder roars go indoors, it's as simple as that. Luckily, our friends at the National Weather Service have systems in place to make sure that we are aware and prepared for such events. When looking at the weather forecast, you may see terms like watches, warnings, and advisories, but what exactly do those mean and what should we do if we see those alerts? Jessica: We will very closely monitor storms and any different factor that we put out, watches, warnings, and advisories for. Um, what we do have is certain criteria in order for things to become a watch versus a warning versus an advisory. So if something is more severe in nature, then it would be considered a warning. Um, and just to break down the definition of each of them, a watch is something where we notice that there's. Favorable conditions for something to develop. Whereas a warning means that conditions are currently happening or very imminent and it's severe in nature, it's gonna cause a lot of different impacts and, um, be more hazardous. Whereas an advisory is very similar to a warning in the sense that it's. Imminent or currently happening, however, it's sub severe. Usually the conditions aren't gonna be quite as impactful or cause as many hazards as a warning would cause. Um, so in that case, anytime we're going through and we're monitoring a storm system or whatever it might be, we're seeing if it's able to meet a certain criteria to be elevated or upgraded to the next step. So whenever we have a watch out, that means that we've noticed that there's favorable conditions. We're keeping a close eye on it, and then only when we see that those conditions actually meet our criteria and break a certain threshold, will we upgrade that then to a warning? Donovan: Jessica had a great analogy of a s'more when talking about weather alerts. Imagine you have all the ingredients of a s'more. You have the chocolate bar, the marshmallows, and some graham crackers, but they aren't quite put together yet. That is sort of like a watch, just like the s'more. All the ingredients of the atmospheric phenomenon are there, but it hasn't quite happened yet. So now let's say you put all the ingredients together, you've got a fully structured s'more. That would be an advisory. The phenomenon is here and it's actively happening, but now let's imagine that maybe the person who made you this smore, double stuffed it, little extra chocolate running down the side, marshmallows, getting all over your fingers. It's just overall a little bit more intimidating. That would be a warning, just like the advisory, the atmospheric phenomenon is here, but it's much more intense. Jessica: So a watch we would recommend just be prepared. Know that this could happen. So with a watch, you wanna be prepared and be ready to go in case you need to take action. Whereas a warning, you need to take action immediately. So if we're saying that there's gonna be a severe hail threat, then in that case, take cover immediately. Get what you do, what you can to get into the safest location as possible, and just make sure that you're taking it seriously because a warning is not something that we play around with, especially because that does activate. People's phone systems. So we, we don't wanna put out a warning unless we're confident about it. So when you see a warning, definitely take caution and, and do what you can to, to follow safety procedures in that case. Ian: Hopefully you're feeling pretty prepared to make a safety plan for yourself in case of an extreme weather phenomena. Before we wrapped up with Jessica, though, we got a chance to ask her what meteorology meant to her and why it is important. Jessica: So meteorology just boils down to the study of weather, but it really goes much far beyond that. As far as being a meteorologist. So yes, we have the foundation that we need from schooling and from taking all of our necessary prerequisite classes to develop this understanding of the science behind weather. Um, but what's really important as meteorologists, that we have the ability to communicate this to the public because ultimately, if we create these forecasts and come up with all of these solutions and have all these groundbreaking scientific discoveries, but we're not able to reach the public and then communicate that information, it's all for nothing. So it's crucial that meteorologists really take the time to really get into the public and, and tell them what's happening. Um, because really we're the barrier between these natural disasters happening and the public being informed and ready to know and know when they need to evacuate. So it's a really important job because it can ultimately save lives at the end of the day. So it's, it's much more than just studying the weather for the fun of it. We do it so that we can have better lead time for whenever we're expecting severe weather or things that will eventually cause hazards and impact the public. We just do our best to not only just study the weather and do our best to contribute what we can to the research and meteorology as scientific field, but also what we could do to educate the public and make them be more weather prepared. Donovan: So now, Whenever you check the forecast to plan an event, take a trip, or even go on a hike, you can thank meteorologists like Jessica for helping keep you safe by providing that information. Ian: Of course, visitor safety here at Joshua Tree National Park doesn't stop there. We have teams of rangers dedicated to ensuring you stay up to date on park conditions and closures due to hazardous weather all throughout the park. Someone who knows a thing or two about flash floods here at Joshua Tree National Park is Alex Nay. Alex: My name's Alex Nay, and I am the facility manager here at Joshua Tree. Previously, I was a road supervisor from 2017 until last month. Donovan: During the monsoon season. When flash floods occur, park visitors should seek shelter by driving out of the park. However, Alex and his team are usually the. First ones on scene to check road conditions and safety, but he does much more than that here at Joshua Tree National Park. Alex: So as a road supervisor, when we come in, in the mornings, we'll go over all the projects that we're working on for the week. We'll go out depending on the time of year, that usually dictates what kind of projects we're doing here in the summer months we're usually in vehicles staying out of the heat. We also take care of all of the road signs that you see, all of the gates that you see as you drive through the park. We also make sure that the shoulders and the drains in the shoulders are prepared so that when we do get rain here in the monsoon season, it's able to flow off the road. Ian: Alex has helped the park manage a lot of flash floods, which can vary in degree quite a bit. We asked Alex if he could give some perspective of what he tends to expect during the monsoon season. Alex: I started working here in 2016. I would say I've been through at least 50 monsoonal rains here in the park. Most years we get about five to 10 heavy rains that we actually have to go out and do mechanical removal of sand off the road. I would say every year it'll be a few days where we get light rains and then we'll get one heavy day of rain. Last year was an anomaly as we went in about 40 days getting rain every day somewhere in the park. Donovan: Alex is referring to the summer of 2022, where a majority of the summer consisted of cloud coverage and record breaking thunderstorms. That monsoon season didn't just affect Joshua Tree National Park, but our other neighboring park service units as well, such as Mojave National Preserve and Death Valley National Park, referring back to a press release from Death Valley National Park on August 5th, 2022. Unprecedented amount of rainfall. Caused substantial flooding within Death Valley National Park. All roads into and out of the park are currently closed. There are approximately 500 visitors and 500 staff members unable to exit the park. This catastrophic event was caused from a sudden downpour of 1.46 inches of rain onto the 1.47 inches from the previous day. That might not seem like a lot, but their annual rainfall is usually less than two inches. According to the release, no one was harmed, but effects of weather events like this are long lasting Here in Joshua Tree National Park, we do everything we can to prepare for extreme flash floods. Alex: So our monsoon season runs from the end of June to the middle of October here. Usually what happens is in June we'll start going through identifying any low areas in the road shoulder that we have to fill in. We'll start making sure that all of the drains that are on the side of the roads are opened. We do a lot of maintenance throughout the year with our shoulders. We'll keep 'em bermed up just so that people are not trying to drive down the drains. And then in the summer before monsoon season, we'll come out and we'll open these drains up to make sure that the water has a good path to get off the road. We also do a lot of work on our dirt roads to make sure that those have the same type of drainages through the windrows to make sure that any rain that comes onto those roads are able to get off. We have a lot of historic roads here in the park and some of these areas are really low and it's hard for the water to get out of them, so we try to create areas in which the, the water can help shed off the road so that, say a visitor is back on Bighorn Pass Road and they get rained on, they're able to get out of there before they're fully closed in by flooded roads. Another thing we'll do is we'll go and we'll pre-stage a bunch of signs around the park to let visitors know that there might be flooding ahead, or there might be areas where there's standing water. You know, standing water in vehicles is not a good mix, you know, hydroplaning happens. So we try to give visitors as much warning as we can when they come into the park that, hey, there's gonna be rain, there's gonna be danger ahead. Make sure that you're, you're paying attention as you drive through the park. Ian: So remember, if you see any sort of closure or warning sign, it is placed there for your safety. It is sometimes hard to conceptualize how water can tear apart a road, but it can happen. Alex: Here in the park, we have various areas that the monsoons affect differently. This is generally how roads are constructed. Here in the desert, we have shoulders that are soft shoulders, they're made up of loose sand. That sand gets compacted over time, but when fast running water that goes over these shoulders, it'll wash away. The water will continue to move on down the side of a hill. It'll take that sand with it, and eventually the asphalt will get undercut. Once that asphalt gets so undercut that it's no longer supported by anything underneath, then that's when the road collapses. This can happen where culverts are installed. If a culvert gets plugged up, this can happen in areas where water has a long runup before it actually gets to the road. There's very little to slow the water down. So once that water's getting to a road network, when it comes off the mountains, it adds a lot of velocity and it's taken a lot of the sand away, and eventually that sand, that's basically what's holding the road up here in the desert. When that is gone, then the road starts washing away. Ian: Once that road is undercut, it is no longer safe to drive on. A common visitor question I get, however, is I'm in the park and a flash flood occurs. Where should I go and what should I do? Although flash flooding could occur almost anywhere through Alex's experience, he's able to identify several areas that are more susceptible to flash flooding and how to stay safe while driving near them. Alex: Here in the park, we don't really worry about that too much in the northern part of the park. That stuff happens a lot down in Pinto Basin Road down to the Southern boundary. So if, if you're south of Cholla Garden on a dirt road, say Dale Road or Black Eagle Mine Road, and you see rain clouds coming, you want to exit the area and get back to Paved road, those areas, Have a very, very fast water flow. When that water comes off the roadway so much that we can lose a foot of road, a foot of sand off of that dirt road. Within minutes in the Cottonwood campground area down to the south boundary. The water basically runs through the canyon. It crosses over the road in various areas. That area, we get boulders two to three feet in size on the road. You don't want those hitting your vehicle. If you're in a park and you see heavy rain clouds coming, usually if you just stay where you're at, you'll be fine. Uh, one nice thing about Joshua Tree is we don't have a lot of area for, for water to gather. So when the rains come, we'll get quick flash flooding, and then within a half hour to 45 minutes, most of that water is receded to the point to where you can continue to drive either further north or out the southern boundary of the park would say. As you're driving through the park after Monsoonal rains, make sure that you're watching the sides of the road. That road still might be held in place just due to the nature of asphalt, but eventually that road will collapse and you don't wanna be on top of it when it happens. Donovan: Alex and his team will not only respond to flash floods, but will often do preparation beforehand. They will often pre-stage in more susceptible areas for flash flooding, and then from there they wait and watch. Alex: The flash flooding starts with a slow trickle. Imagine like you're filling up a bathtub right in the beginning. As soon as that water starts building up, it slowly starts creeping up in depth. That's kind of how a flash flood is. And then all of a sudden, the next thing you know, you've got boulders rolling through the road. You have water flowing over the road at a very fast pace, and once that water gets up to halfway up the side of your tire, that's when you, you gotta worry about floating away. But there's no connectivity in Joshua Tree. So we'll let visitors know that, hey, rains are here, or they're coming, you should exit the area or. Hold in place. Once we start seeing the water come across the road, we'll put in blocking positions. We'll make sure that visitors don't go through these areas. When we get heavy rains, uh, we usually get about 20 miles of roadway that can get covered in sand. Ian: Once that damage or coverage of debris occurs, Alex's team kicks into action to plow the debris off the road or determine if the road is even safe to drive on at all. If not, a closure might be needed. Closures only occur when absolutely necessary. So it is important to take them seriously for your own safety. Speaking of safety, Alex had one last piece of advice to give visitors when visiting the park during the monsoon season. Alex: I would say during monsoon season, pay attention to all the weather alerts. Also follow the park social media pages while I'm out and about. Take photos for record purposes, and I send those in into our social media people. So you might get an idea of what's going on in the park. Donovan: What we communicate with you, whether in the visitor center or on social media, it's always with your safety in mind. We understand that not everything can be planned for, but nothing can ruin a trip faster than not being prepared and having to face the unexpected head on. It's your trip and your experience. Ian: So remember, thank a meteorologist while checking the weather. Ideally, don't get struck by lightning. Pay attention to road signs and try to plan ahead for the unexpected. Donovan: Where Two Deserts Meet is an official production of Joshua Tree National Park, produced and edited by Donovan Smith, co-hosted and written by Donovan Smith. And Ian Chadwick. We'd like to extend special thanks to Jessica Leffel and Alex Snay for taking their time to talk with us. Sharon Lee Hart for letting us use her art titled Split as the Cover Art for Where Two Deserts Meet and Barstool for their songs, Lengthy, luckily fills Slowing Lover and Feathers Soft. For more information about the park and current conditions, visit our park website at www.nps.gov/jotr. Happy Trails.