The Drought Discussion Podcast

Episode 1. Seasonal Climate Outlooks and Grass-Cast - July 6, 2022

July 14, 2022 Drought Learning Network Season 1 Episode 1
The Drought Discussion Podcast
Episode 1. Seasonal Climate Outlooks and Grass-Cast - July 6, 2022
Show Notes Transcript

We bring you this podcast with the intention of helping you figure out how much rain to expect this season and - if you’re managing rangelands - how much forage you might get. During the growing season we share seasonal precipitation outlooks from NOAA’s National Weather Service Climate Prediction Center and grassland productivity forecasts from Grass-Cast. Grass-Cast gives you a heads-up in late-spring and early summer for how well your rangeland grasses could grow during the upcoming summer season, depending on whether precipitation in your area ends up being above, near, or below-normal.

Please visit
https://bit.ly/droughtpod to view the maps discussed in this episode. Or click here to load a PDF.

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[00:00:00] Caiti Steele: Welcome to the Drought Discussion podcast. Thanks for joining us as we share the latest drought, precipitation and forage outlooks for Arizona, New Mexico and the Southern Plains. The information in this podcast is best used in combination with local knowledge of soils and topography, plant communities, grazing history and other conditions.

[00:00:20] It should never be used as a sole basis for decisions or to replace local observations of the land you manage. 

[00:00:30] I'm Caiti Steele, Southwest Climate Hub coordinator and director of the ARID project at New Mexico State University. 

[00:00:40] Tonya Bernadt: And I'm Tonya Bernadt, the Education and Outreach specialist at the National Drought Mitigation Center. 

[00:00:46] Caiti Steele: In today's podcast we've asked Julie Elliott, rangeland management specialist with the Natural Resources Conservation Service and liaison to the Northern Plains Climate Hub to talk about the early season forage predictions from Grass-Cast for the Southwest and Southern high Plains. 

[00:01:03] Tonya Bernadt: And because when we interpret Grass-Cast maps, we need to consult seasonal outlooks of precipitation and temperature.

[00:01:09] We've asked Curtis Riganti, climatologist with the National Drought Mitigation Center, to talk about the seasonal outlooks from the National Weather Services Climate Prediction Center. For images of the maps that Curtis and Julie are discussing, please go to bit.ly/droughtpod. That's all one word.

[00:01:31] Or you can also find this link on our podcast page on Buzzsprout. Take it away, Curtis. 

[00:01:38] Curtis Riganti: Okay, good morning. Thanks for having me on Tonya and Caiti. So the sub-seasonal climate outlooks for Arizona, New Mexico and the Southern High Plains can be found from the, as was mentioned earlier, the National Weather Services Climate Prediction Center.

[00:01:53] So there are a few different maps that we can look at here that'll kind of show us what to expect over the next few weeks to the next few months. Both just in terms of general weather and in terms of drought. So first I want to draw your attention to the contours on the maps, where they'll show on the temperature outlooks. Basically the redder, the colors, the higher probability in the opinion of the forecaster for there to be above normal temperatures for the area over which those contours are.

[00:02:27] So let's say that you're sitting in Phoenix. If you are in 60 to 70% contour for above normal temperatures, that means that the forecaster thinks that Phoenix has a 60 to 70% chance of seeing above normal temperatures for whatever the time of year it is that the forecast is being made for. So, as an example, you can also look at these types of maps in terms of precipitation.

[00:02:56] So a map that was made at the end of June for July, 2022 shows above normal chances for above normal precipitation covering much of central and Western New Mexico into central and Eastern Arizona with the highest probabilities along the state line, down to the Mexican border. And so what these maps are showing us right now is that there is a 33% or higher chance for above normal precipitation. 

[00:03:26] For this time of year and for these areas for the month of July, in the opinion of the forecaster. Now, as we go out to three months and these forecasts are a couple weeks older, so we may have some gained some new information since these were last updated, but the higher probabilities for above normal precipitation.

[00:03:48] For the July through September period, as of June 16th are mostly focused over Arizona, specifically south central Arizona, but really some, at least slight probabilities to have higher than normal precipitation across most of the state. Whereas parts of Eastern New Mexico look like they have a larger probability of seeing below normal precipitation for the same time period, with equal chances to see either near normal, above normal or below normal between these areas in central and Western parts of New Mexico. Now, as we look forward for the monthly drought outlook right now, again, most of these states, while they've seen some improvement recently due, due to the ongoing early start of the north American monsoon.

[00:04:40] We still have widespread, severe, extreme, and even some exceptional drought remaining in Eastern New Mexico. And so as we look forward over the next month, based on the forecast from the climate prediction center issued on June 30th much of Arizona and New Mexico, excluding far Eastern parts of the New Mexico high planes are expected to see drought remain but improve.

[00:05:06] Whereas parts of central and Eastern Arizona may even see drought be completely removed during July. Now moving forward through the end of September, you see a pretty similar spatial pattern emerge where drought removal appears likely in parts of central and east central Arizona, even into parts of Southeast Arizona.

[00:05:30] And then a small area of drought removal is also likely near El Paso and just to the south of Las Cruces. Whereas most of the rest of Arizona, New Mexico, again, excluding the far Eastern high plains of New Mexico. We'll likely see drought remain. Now, as we go further east into the high plains of Western Oklahoma, the Texas panhandle, Southwest Kansas, Eastern Colorado.

[00:05:58] We're likely to see drought persist or even develop over the next several months in areas where it isn't already going. 

[00:06:05] Caiti Steele: So Curtis, I was seeing from the three month outlook, which is the one I usually visit for looking into the future a little longer. It's showing that there's a 33 to 40% chance of high precip for the rest of monsoon for Arizona.

[00:06:19] If I was looking at my weather app and it said we have a 33% chance of precipitation tomorrow, I'd be pretty optimistic. Do they have a good reason to be optimistic in Arizona, do you think? What does that, 33% to 40% chance even mean when it's spread over three months? 

[00:06:38] Curtis Riganti: Yeah, that's a great question. So what, what that means is it is different from looking at day to day weather like you would on a phone app where those forecasts are tailored, right to your location. And they're just basically about tomorrow. What do we think the probability of rain or precipitation in anytime of year is to occur? So it's basically a one in three chance. If they forecast 33% chance of rain tomorrow. What this is referring to is there's a normal amount of rain that falls for any particular location based on their own basically climate history or data that's been collected there in the past.

[00:07:19] And so as meteorologists and climatologists for different locations, we know what that normal amount is. So what we're trying to do here is say based on long range, basically long range forecasts that we can make using different models, pattern recognition, different ocean circulations and other things that occur over different parts of the globe, based on those different things.

[00:07:44] We can get a general idea of what areas might see more precipitation than they're used to, less precipitation than they're used to, or about the same. And again, you can do the same thing with temperature. So a 33 to 40% chance of above normal precipitation. How you can hear that is if you know what you normally get for your location.

[00:08:06] And you're in that contour of 33 to 40% for above normal, you can say that the probability of seeing it more than you usually get is slightly higher than that of getting near what you normally get, or less than what you normally get. So it's, it's not a forecast for specific amount of rainfall or even a forecast of, is it going to rain tomorrow or sometime in the next week?

[00:08:32] It's if you add up all the precipitation over this three month period, does the person making the forecast think that it's more or less likely to have above normal precipitation? In this case it's slightly more likely than not to have it. 

[00:08:48] Tonya Bernadt: According to the three month climate outlooks, it looks like there's a good chance that the Southern Plains and most of New Mexico is going to be warmer and drier over the next three months.

[00:08:58] And the seasonal drought outlook says drought persists over the Southern High Plains. But that line separating far east New Mexico from the rest of New Mexico is in a slightly different position on the drought outlook and on the seasonal precipitation outlook. I'm wondering, Curtis, what would you say to those folks in the Eastern third of New Mexico, about what to expect? Is drought going to improve or persist? 

[00:09:25] Curtis Riganti: Thanks Tonya. So what we're looking at right now, and as of June 30th, the current forecast is for other than, probably about the Eastern row of counties or so we're probably looking at improving drought conditions and covering most of New Mexico. But again, you do see a large area of persisting conditions across far Eastern New Mexico into the rest of the Southern High Plains regions of the Oklahoma and Texas panhandles in adjacent parts of parts of Kansas and Colorado. One potential reason that these maps could be maybe so slightly different things, or at least seem to first different areas are in different levels of dryness right now. And so perhaps the amount of the, the weather that's needed to change those barriers from place to place.

[00:10:17] Additionally, the current three month outlook that we're discussing was issued on June 16th. Whereas the most recent seasonal drought outlook was issued June 30th. So it's possible that new information, basically new information has come along in the last couple of weeks, too that changes what we may be looking at over the next several months. Not having made the forecast myself, I can't say for sure what the reasoning for those maps being slightly different are, but those are some possibilities. 

[00:10:47] Caiti Steele: Thanks, Curtis. That was a really helpful explanation of what to expect. Looks like just the Arizona ranchers and perhaps a few folks in New Mexico maybe have something to be a little bit cheerful about with this monsoon.

[00:11:01] Now we're gonna turn to Julie who will tell us about Grass-Cast and what we might expect in terms of forage production this summer. Over to you, Julie. 

[00:11:11] Julie Elliott: Thanks so much, Caiti. Yeah so Grass-Cast is a forecast. So thinking about the weather forecast, it's looking forward forecast of what total above ground production might be for grasses.

[00:11:25] The maps show the difference from the long-term average. So in the Southwest, we, we run it for 36 years and in the Great Plains we run it for 38 years. So the maps are showing compared to the last 36 years, what do we expect the end of season production to be compared to that long-term average? So you interpret the maps and you look at the scale and you'll see that there's blue colors, which is above the long-term average expectation.

[00:11:55] There's green, that's really right about normal below 55% or above 5% of the long-term average. So really normal. And then we gradate yellow to red, to brighter red or darker red as we get farther and farther away from that long term average. So that's what the maps are showing us. We have two mapping or two forecast models. One is specifically for the Southwest for Arizona, New Mexico. That's because Arizona New Mexico have a unique system where they have two distinct growing seasons. They have one in the spring that's fed by moisture received from the beginning of the year to the end of May.

[00:12:36] And then there's more or less a pretty hard stop at the end of May. And then there's a second growing season where the summer grasses and that really runs off for the moisture receive from the first to June through the rest of the summer. So we create a spring map and then we start over again in June with summer maps. We create the maps every two weeks.

[00:12:57] So when we're looking at the Southwest maps, Arizona, New Mexico, particularly right now the most recent forecast was June 28th. Because we only have one month of data feeding into these summer maps, these are pretty speculative maps. We don't have a lot of data feeding into those maps to make a projection out for three or four months out.

[00:13:18] So when you look at the maps, you might say, well, the above average precipitation or above normal precipitation shows above normal production and the below normal precipitation shows below normal production, generally speaking, and the near normal precipitation shows near normal production is not really very informative.

[00:13:36] And part of that is because the maps are so early in the season. Although if you pull up the most recent maps, you'll see that there are some areas, sadly enough, even in the above normal precipitation scenario, that that are not blue, there's even some spots that are yellow. And on the contrast, there's some lucky areas in New Mexico where even below normal precipitation right now Grass-Cast is forecasting that we would have above normal production in those scenarios. 

[00:14:08] If you click on the radio button for the Great Plains, you'll notice that heck, eastern New Mexico is in the Great Plains map as well, or the Great Plains forecast as well. But if you compare those maps, you're going, they are not saying the same thing. Well, that's because the Great Plains forecast is created on a one growing season scenario.

[00:14:29] So the growing season starts March, April, and it runs through September October for the very tail end of the season. So the New Mexico, the in the, on the Great Plains map, the New Mexico portion that's in that forecast area is being built on that assumption that they have one growing season. So users in New Mexico on the Eastern side, you need to decide, do you have this unique two season system?

[00:14:59] Or do you have one season really, that starts in the spring with the early, early grasses transitions over to the summer grasses and then transitions back to the, to the cool season grasses in the fall, if you have adequate moisture. So that's why those two maps look so different from each other. So let's just step back and we'll look at it from a 10,000 foot level.

[00:15:20] As Caiti mentioned, the Arizona folks have a reason to maybe be optimistic. And right now the Grass-Cast maps would agree that even in a near normal precipitation scenario, Grass-Cast the model is predicting that most of the area should see at least near normal production. And some areas could expect even as much as maybe 30% above the normal or average production than what they might normally have. 

[00:15:48] On the other hand, if the spigot were to shut off and the monsoons don't come, do not come through. Yeah. That's why we say cautiously optimistic because we do not know for sure if those monsoons are gonna come through and if they do not, the spring drought could certainly carry on into the summer growing season, even though those two growing seasons are specific. Moving on to the Southern Plains.

[00:16:15] Sadly and really reflecting what Curtis said about that Eastern border of New Mexico and spreading on to the east. Yeah. Grass-Cast even in an above normal precipitation scenario, the model is showing continued below the long term average production and even severely so. More than 30% loss of the total production for parts of New Mexico, the Panhandle, texas, Oklahoma reaching up into Colorado and, and into Kansas.

[00:16:46] So definitely expecting continued drought, even if the precipitation were to turn around drought conditions for the grasses and some of that's just because we've gotten as far as we are this far into the growing season, and it's really hard to turn this truck around when it's headed down so far down the path of drought.

[00:17:08] So when I was saying parts of Arizona, it really is pretty scattered across the state. So I'd encourage you to go check out the website, grasscast.unl.edu, or just type Grass-Cast into your favorite web browser. It'll take you to the site and click on the Southwest radial button. You can see the areas that the model is predicting to have below average production for this year, even with perhaps normal precipitation.

[00:17:36] Tonya Bernadt: So Julie, I have a hypothetical question for you. Say I'm a rancher in Northeast New Mexico, and I've been pretty conservative about my stocking rates been rotating my cattle frequently between different pastures. Then there's this guy down the road who lets his cattle graze down to a couple of inches and really beats up his pastures.

[00:17:56] Grass-Cast seems to suggest that we would both get the same amount of forage. Can you explain that to me a bit more? 

[00:18:03] Julie Elliott: Yeah sure, Tonya. That's a, that's a great question because management plays a huge role in how much production you actually can expect from your pastures. Grass-Cast is really is looking at that 10,000 foot level.

[00:18:17] And it's, it takes the soils information, it takes the plant communities that are expected to be growing there and the past weather information and combines it all together to create this outlook. So it doesn't have a way to look at each individual pasture and say, oh, this pasture, obviously doesn't have the plant community that we are expecting to be there.

[00:18:40] It just, it doesn't have the capacity to handle that much data. And I don't know that anybody would agree that we have the ability to get that kind of data. So it is looking at everything as if it has the plant community that's expected to be there, which may or may not be the plant community that really is there.

[00:19:00] Also Grass-Cast doesn't have any way to know what's happened to the moisture that's out there. It doesn't have any way to know the plants that are there. How deep a root system do they have, how vibrant or healthy are they? So it is across the board assumption of Grass-Cast that the plants are healthy and they have good root system, and that they're even and present on the range.

[00:19:22] Caiti Steele: Julie, that makes me think about the state and transition models from the NRCS that show ecologic dynamics on Rangelands. I'm guessing that Grass-Cast from what you just said, that Grass-Cast doesn't show which ecological site you're on or doesn't show the ecological state or states that your ranch is in.

[00:19:44] So how important is it that ranchers are familiar with ecological sites and states of their pastures? 

[00:19:51] Julie Elliott: Yeah, that's a really good point, Caiti, just as I explained with Tonya that Grass-Cast doesn't have a way to know what really is there. Ecological sites tell us what vegetation to expect and the ecological states within a site give us an idea of the production that that's reasonable for that site. It certainly some ecological sites can vary even a thousand pounds or 2000 pounds from ideal or the best plant community that could be out there to some degraded plant community that's living in, in Tonya's neighbors, hypothetical rangeland.

[00:20:27] So, you need to know what, what you can expect. And that's part of the reason why Grass-Cast, if you look at the maps, it's all given in percentages. We're not saying that we expect there to be 2000 pounds in any particular grid cell we're saying we expect 20% less production or 20% more production than the long term average.

[00:20:51] Again, assuming that those plants are really present. If you have some plant community there that doesn't have the potential to grow 20% more, no matter how much water you pour on it, then obviously you're not gonna see that 20%. So it is important to understand the dynamics and the natural variability that's within your rangeland.

[00:21:10] And if there's, if there's a plant community that could be more productive than what you currently have. 

[00:21:17] Caiti Steele: Thanks, Julie. I think, perhaps, ecological sites and ecological states should be a feature that we cover in the winter. Once the growing season is over. Watch this state. 

[00:21:28] Tonya Bernadt: Thank you again to Curtis and Julie for shedding, some light on how to interpret seasonal outlooks from the Weather Service and Grass-Cast. We'll be back in a couple of weeks to see how the seasonal outlooks may have changed and to check out what the Grass-Cast maps are showing us. 

[00:21:44] Caiti Steele: And thanks to our listeners too. If you have any questions, comments, or requests, please feel free to reach out to us via the podcast page. We'll be very happy to hear from you and fingers crossed. We all get some rain between now and next time. 

[00:22:01] Tonya Bernadt: This podcast is brought to you by the Southwest Drought Learning Network, National Drought Mitigation Center, Agro-Ecosystem Resilience in times of Drought, the Sustainable Southwest Beef project, the Southwest Climate Hub and the Northern Plains Climate Hub.

[00:22:20] Thanks for listening.