Agricultural Weather and Climate Forecast and More

Econintersect Weather and Climate Forecast Update 26 May 2014

Written by Sig Silber

Let’s talk about agriculture.

Certainly an important question is how will El Nino impact food production in the U.S. and elsewhere.  It is not a simple question with an easy answer.

These are not specialty crops but they are some of the major crops grown in the U.S. and crops that are very impacted by weather.

It is a fairly concentrated area.

Soybeans overlap a lot with corn giving farmers a decision to make based on expected product pricing.

There are a lot of cotton growing areas thus a lot of places to be helped or hurt by the weather and climate. In the long term,  I guess we should be looking for Anthropogenic Climate Change to result in the cotton belt gradually expanding north. But today I am focusing on the short term.

I assume they got a late start with spring wheat. I need to check on that.

Winter wheat is a crop where we will watch the impact of a possible El Nino closely.

Notice the maps are shown by climate division so it is easy to track the weather for those crops. Those climate divisions shown as growing areas for certain crops are not the only locations that those crops are grown. Cotton is grown in New Mexico but apparently it is not grown sufficiently consistently in any of the climate divisions in New Mexico to be shown. So these maps show the most important climate divisions for these crops.

I wish I had a similar map for pecans. If anyone has it, please forward me the information.

Low frequency (long) climate cycles

Since 1998 the climate in the U.S. has been controlled mainly by the influence of the cycles of the Atlantic and Pacific oceans and the impact on drought frequency is shown by the following maps:

McCabe (with co-authors) has published on the above in 2003 and 2007. I happen to prefer the 2003 article which you can find here and the more recent 2007 version here.  I do not think the maps have changed from one edition of the article to the next and if they have they could only change slightly since adding five years of data to a close to 200 year data base is not going to change the results of the analysis to any great extent.

In terms of interpreting these maps, there are basically four combinations of the two ocean cycles. The Pacific (PDO) can be unusually warm (+) or cold (-) and similarly the Atlantic can be unusually warm (+) or cold (-). The above maps show the drought frequency calculated by McCabe et al with red being drought prone and blue being less than normal (25%) drought and the four combinations are:

1. Pacific Warm(+), Atlantic Cold(-) designated A above
2. Pacific Cold(-). Atlantic Cold(-) designated B above
3. Pacific Warm(+), Atlantic Warm(+) designated C above
4. Pacific Cold(-), Atlantic Warm(+) designated D above

The phases of these cycles last for two to four decades with the Atlantic cycle (officially called an oscillation) tending to have phases that last longer than the phases of the Pacific but that is subject to further study. At any rate, these ocean cycles have a big impact on our climate I say climate because climate is defined as a thirty-year pattern of weather and a phase of these cycles can last thirty years.

But within these low frequency (long) cycles you have the higher frequency ENSO cycle which gives us variations from this overall pattern at a faster rate and we are going to have the El Nino Phase of the ENSO Cycle soon or at least that is the prediction. So you will have El Nino superimposed on the PDO-/AMO+ combination described by “D” in the above McCabe maps. If it is a strong El Nino it will have a more powerful impact than the Ocean Cycles. If a moderate El Nino, perhaps is just cancels out the impact of the ocean cycles.

So now we have to consider the impact of the coming El Nino. This chart shows the impacts for December through February.

And here is the information for June through August. As you can see, El Nino (as is La Nina) is a worldwide event but today I am focusing on the U.S. impacts.

Of course there are other cycles that impact North American and Europe one of which we have experienced last month which was the North Atlantic Oscillation (NAO) which is related to the Arctic Oscillation (AO) which tends to impact things a bit further west. Somehow our cold winter in the Northern Tier of the U.S. and weather in parts of Europe were impacted by the NAO which is described by differences in air pressure levels at different locations. It is all connected but not yet fully understood.

And off course the relentless warming due to anthropogenic climate change impacts everything but not necessarily in ways we understand at this point in time, but people are trying to figure it out. Some claim more success than I believe is warranted especially with respect to what is going to happen over the next fifty years because the cycles I have described in this article often referred to as “internal variability” are likely to dominate Climate Change in terms of impacts on climate for some time.

Back to El Nino. What will the impact be? I have not figured it out yet. Perhaps you can. Money can be made by those who do as it certainly will impact agriculture commodity prices. We all know where citrus is grown in the U.S. California and Florida so an El Nino raises the risk of frost in Florida. The West especially the Southwest will be wetter especially in the winter. But it is not clear to me exactly how our major grain crops will be impacted but I have seen articles that have made some forecasts on that.

Back to the topic on the chances of having an El Nino and a strong El Nino.

Australia weighs in on El Nino – Issued on Tuesday 20 May 2014

“Tropical Pacific Ocean edges further toward El Niño Issued on Tuesday 20 May 2014 The tropical Pacific Ocean continues a general trend toward El Niño, with just over half of the climate models surveyed by the Bureau suggesting El Niño thresholds will be exceeded by August. An El Niño ALERT remains in place, indicating at least a 70% chance of an El Niño developing in 2014. The tropical Pacific Ocean surface has warmed steadily since February, with sea surface temperature anomalies increasing by 0.5 to 1.0 °C. For El Niño to be established and maintained, the sea surface needs to warm further, and be accompanied by a persistent weakening of the trade winds and a consistent increase in cloudiness near the Date Line. In the past fortnight, trade winds have generally been near normal, though have weakened once again in recent days.

El Niño has impacts on many parts of the world, for example, below-average rainfall in the western Pacific and Indonesian regions and increased rainfall in the central and eastern Pacific. For Australia, El Niño is usually associated with below-average rainfall over southern and eastern inland Australia, with about two thirds of El Niño events since 1900 causing major drought over large parts of the continent.

The Indian Ocean Dipole (IOD) is currently neutral. Model outlooks suggest the IOD is most likely to remain neutral through winter, with two of the five models surveyed suggesting a positive IOD may develop during spring. Positive IOD events often coincide with El Niño and are typically associated with large parts of southern and central Australia experiencing lower rainfall than usual.”

North American Monsoon (NAM)

Since I am on a roll, here is the latest forecast for the North American Monsoon.  This version was made specifically for New Mexico and I would have expected to find a companion report issued out of Arizona but I did not not find it. This is a very interesting report for many reasons including:

It is unusual for NOAA to claim either that they can forecast the North American Monsoon (NAM) or that El Nino influences the NAM. So this is groundbreaking. Notice the disclaimer.

“Why not use any of the coupled (atmosphere – ocean) climate prediction models including NOAA/NCEP, NOAA/GFDL,IRI, NCAR, NASA, and Canada’s CMC in this study? While these models are vastly improved, only two of the models have skill (accuracy) scores for any portion of New Mexico in July, August and September of greater than 30%. The GFDL and NASA models show the most skill with regard to predicting precipitation in New Mexico during the monsoon. The remainder of the models have skill scores during the monsoon of 10% or less.”

Secondly, the report notes the current condition of the Pacific as measured by the PDO index. This index has been reporting the PDO Negative or cold condition but recently has been measuring warm i.e. PDO Positive not just in the area where El Nino is measured. Similarly the Atlantic AMO index has been recording negative numbers. So for the first part of the year we have index readings that suggest PDO+/AMO- which is combination “A” in the above McCabe maps i.e. the low-drought situation for the Southwest. Is this a true flipping of the PDO (and or the AMO)? Here is what the special North American Monsoon Report says:

Note: PDO index values are used to reflect current SSTAs in order to evaluate moisture availability from the northeast Pacific Ocean and not to forecast long-lived PDO phase changes.

So not only do we have a very interesting report on the North American Monsoon as it impacts New Mexico but we clearly have a recognition that there has been at least a short-term reversal of the condition of both the Pacific and Atlantic. The change in the Atlantic could be explained by the North Atlantic Oscillation and the change in the PDO by the influence of the El Nino but either way it is a very interesting situation.

Personally I think these changes in the index are transitory but at this point there is no way to tell.

Click here for the latest data from NOAA (National Oceanic and Atmospheric Administration) and other sources on the Econintersect Weather and Climate page.