The monsoon season
17 August 2006, 1:30 PM MDT
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Transcript
donn:
Is the cycle of drought and then flood what caused the Anasazi to resort to canibalism and then leave Chaco Canyon?
John Fleck:
I'll sidestep cannibalism, but archaeologists think there may be a connection to the drought/flood pattern and the Anasazi departure. According to Jeff Dean, an archaeologist at the University of Arizona, the decline of the Anasazi happened with rainfall patterns - both summer and winter - became more highly variable in both space and time. For much of the Anasazis' tenure in the Four Corners, rain fell dependably somewhere in the region every year somewhere, meaning that grain could be traded from places that had good harvests to places that had bad harvests. Dean and others argue that pattern broke down, with highly variable periods here drought happened simultaneously regionwide, with both summer and winter precipitation failing together. Similar pattern happened here in the drought of the 1950s. David Stuart's bood Anasazi America gives a nice account of all this.
Avelino:
Why has it seemed as though the storms are moving in non-traditional directions for monsoons?
John Fleck:
Summer rain patterns are controlled by a big high pressure system that generally hovers somewhere around the western or central US. It creates a large clockwise circulation of air. When it's on top of us, it doesn't rain. That obviously hasen't happened this year. When it's to the east - a classic monsoon - it pulls a big tap of moisture up out of Mexico and contributes to the rain. That's what's happening now, which seems "normal." In July, the high was sitting to the north of us, according to Charlie Liles, the weather guru at the local National Weather Service office. It pulled moisture out of Mexico, which then swung all the way over to top, north of us, then down onto New Mexico from the north. It's a less common monsoon pattern, according to Liles, but it does happen.
(P.S. A lot of people use the Weather Channel for their weather web site, but I strongly recommend Charlie's page. These people are very smart and they're right here.)
(P.S. A lot of people use the Weather Channel for their weather web site, but I strongly recommend Charlie's page. These people are very smart and they're right here.)
Greg:
Re: the drought
Is all this summer rain better for easing the drought than a lot of winter snowpack?
Is all this summer rain better for easing the drought than a lot of winter snowpack?
John Fleck:
It depends on what you mean by drought. :-)
The rains have really improved soil moisture conditions. Down at the Sevilleta, where the University of New Mexico biologists have soil moisture sensors, the ground is saturated. That means the grasses and other plants are all fat and happy. So by that definition of drought, it's great drought relief. But the effect on reservoir levels is minimal. (More on this in a minute.)
The rains have really improved soil moisture conditions. Down at the Sevilleta, where the University of New Mexico biologists have soil moisture sensors, the ground is saturated. That means the grasses and other plants are all fat and happy. So by that definition of drought, it's great drought relief. But the effect on reservoir levels is minimal. (More on this in a minute.)
donn:
Should we all move to Oregon before it's too late?
John Fleck:
No. The rain there means their green chile sucks.
Lloyd S/ Nelson:
How have the recent heavy rains affected the state's major reservoirs, e. g., Elephant Butte?
John Fleck:
Lloyd -
This is a great question. Typical summer rains have almost no effect on reservoir levels. But this summer is anything but typical.
Over the first 10 days of August, Elephant Butte's storage rose 40,000 acre feet. That's a lot of water - almost as much as the city of Albuquerque consumes in a typical year. So it's a significant contribution. But it's still far less than you get flowing into the Butte in a wet winter. At the end of an average July, Elephant Butte has 1.2 million acre feet of water. This year, it had just 189,000 acre feet. So you can see that, while this current inflow is nothing to sneeze at, it's pretty insignificant in terms of the deficit we're running.
This is a great question. Typical summer rains have almost no effect on reservoir levels. But this summer is anything but typical.
Over the first 10 days of August, Elephant Butte's storage rose 40,000 acre feet. That's a lot of water - almost as much as the city of Albuquerque consumes in a typical year. So it's a significant contribution. But it's still far less than you get flowing into the Butte in a wet winter. At the end of an average July, Elephant Butte has 1.2 million acre feet of water. This year, it had just 189,000 acre feet. So you can see that, while this current inflow is nothing to sneeze at, it's pretty insignificant in terms of the deficit we're running.
donn:
Is there a link between the snow this week in South Africa and the wet weather here?
Why has this hurricane season been light so far in the Gulf of Mexico are we getting all the moisture?
Why has this hurricane season been light so far in the Gulf of Mexico are we getting all the moisture?
John Fleck:
I don't know about the South Africa thing. Prolly too far away to matter.
I think the hurricane-monsoon part of your question is very interesting, though. Last year, we had a bangup hurricane season, while the summer rains here were lousy. This year, both situations are reversed. Could there be a connection?
When I posed this question this morning to Dave Gutzler, the UNM climate guru (the advantage of questions ahead of time!), he suggested it was an interesting conjecture, but that scientists don't know enough to say. Hurricanes are affected by large-scale patterns of highs and lows across the northern hemisphere, as are our summer rains. There also is a lot of very active research into the way in which Atlantic Ocean temperatures influence rain in the continental U.S. And we know those oceans temperatures influence hurricanes. But whether the same patterns influence both, they just don't know enough to say.
I think the hurricane-monsoon part of your question is very interesting, though. Last year, we had a bangup hurricane season, while the summer rains here were lousy. This year, both situations are reversed. Could there be a connection?
When I posed this question this morning to Dave Gutzler, the UNM climate guru (the advantage of questions ahead of time!), he suggested it was an interesting conjecture, but that scientists don't know enough to say. Hurricanes are affected by large-scale patterns of highs and lows across the northern hemisphere, as are our summer rains. There also is a lot of very active research into the way in which Atlantic Ocean temperatures influence rain in the continental U.S. And we know those oceans temperatures influence hurricanes. But whether the same patterns influence both, they just don't know enough to say.
climatron:
Is the drought over yet?
John Fleck:
Climatron asks the best question of the day, a fat moth hanging before my spider's web....
Back in the 1980s, two drought science/policy researchers, Don Wilhite and Mickey Glanz, combed the scientific literature looking for definitions of drought. They found something like 150. So the best answer is, "Depends on what you mean by drought." But you knew that. :-)
As I mentioned before, soil moisture is great right now. The biologist I talked to yesterday from the Sevilleta said the plants have bounced back nicely. The ecosystems here are relatively well adapted to wet-dry cycles, and the plants "know" how to hunker down when it's dry and take advantage of the wet bits.
The Rio Grande is running strongly, too, so riparian systems are flush right now.
Reservoir levels may be the most important definition of drought here, though, because they're the human response to climate variability in the West, storing up in wet times to tide us over in the dry. By that measure, this stuff is better than having a lit cigar stuck up your nose, but it's not going to end "hydrologic drought."
Back in the 1980s, two drought science/policy researchers, Don Wilhite and Mickey Glanz, combed the scientific literature looking for definitions of drought. They found something like 150. So the best answer is, "Depends on what you mean by drought." But you knew that. :-)
As I mentioned before, soil moisture is great right now. The biologist I talked to yesterday from the Sevilleta said the plants have bounced back nicely. The ecosystems here are relatively well adapted to wet-dry cycles, and the plants "know" how to hunker down when it's dry and take advantage of the wet bits.
The Rio Grande is running strongly, too, so riparian systems are flush right now.
Reservoir levels may be the most important definition of drought here, though, because they're the human response to climate variability in the West, storing up in wet times to tide us over in the dry. By that measure, this stuff is better than having a lit cigar stuck up your nose, but it's not going to end "hydrologic drought."
sharon:
Is an end in sight soon to this rain?
John Fleck:
Not as far out as the current models can project. There's rain in the forecast for Albuquerque and environs for at least the next week. It varies from place to place around New Mexico, but the whole state should see significant rain somewhere for at least the next week. (Beyond that, the forecast models lose some of their predictive power.)
You didn't exactly ask this, but I'll take the opportunity anyway to share the latest longer term forecasts, which came out today out of the Climate Prediction Center, is starting to talk about the possibility of a wet winter, a result of the nascent El Nino that seems to be taking shape. Don't bet the farm on this yet, but it's out there.
You didn't exactly ask this, but I'll take the opportunity anyway to share the latest longer term forecasts, which came out today out of the Climate Prediction Center, is starting to talk about the possibility of a wet winter, a result of the nascent El Nino that seems to be taking shape. Don't bet the farm on this yet, but it's out there.
climatron:
If an average citizen was interested in getting more involved with water and conservation, what would you recommend they do? How can one make a meaningful difference?
John Fleck:
I don't know if you're in Albuquerque, Climatron, but there's a "Water Fiesta" here this Saturday from 9 a.m. to 2 p.m. at the Alameda Open Space, where Alameda crosses the Rio Grande. They're going to be out talking about municipal water conservation, with apparently fun games for the kids or something.
donn:
Do most scientists believe the increased temperatures around the globe is causing New Mexico to become wetter?
John Fleck:
Donn -
There's no way to tell, but what we're seeing is consistent with what global warming science predicts.
Regional-scale global warming projections are not very reliable right now. In general, global warming science predicts things will get wetter overall, which we seem to be seeing. But - and this may seem counterintuitive - the scientists also predict more droughts, which we also seem to be seeing. That is because, in general, as the planet warms we should see an enhanced hydrologic cycle. That means wetter wets and drier dries, essentially, which is what we've been seeing in New Mexico's recent summer rainy seasons. In the 1990s, we had a bunch of extremely wet monsoon years. Lately, we've had quite a few that were extremely dry. Scientists can't point to this and say it's definitely caused by global warming, but it's certainly consistent with scientists' predictions.
There's no way to tell, but what we're seeing is consistent with what global warming science predicts.
Regional-scale global warming projections are not very reliable right now. In general, global warming science predicts things will get wetter overall, which we seem to be seeing. But - and this may seem counterintuitive - the scientists also predict more droughts, which we also seem to be seeing. That is because, in general, as the planet warms we should see an enhanced hydrologic cycle. That means wetter wets and drier dries, essentially, which is what we've been seeing in New Mexico's recent summer rainy seasons. In the 1990s, we had a bunch of extremely wet monsoon years. Lately, we've had quite a few that were extremely dry. Scientists can't point to this and say it's definitely caused by global warming, but it's certainly consistent with scientists' predictions.