Using Summertime Patterns to Predict Upcoming Winter Conditions

The hunt is now on more fiercely than ever: with meteorology growing and advancing at exponential rates in the last few decades to the present day, researchers are working harder than ever to find patterns in the weather to accurately predict long range conditions, months in advance. One aspect of this hunt is being able to predict the upcoming winter using conditions observed in the fall, or even summer. We'll take the time today to discuss methods that may or may not be useful in such long range predictions.

1. Nature Signs
This is a personal favorite of mine, due to the mystery surrounding it. Many weather enthusiasts, and people in general, believe that nature can point us to the intensity (or lack thereof) of the upcoming winter. I've heard mentions of trees producing anomalous fruit in the summer, animals acting in a suspicious manner, and even the color of certain shrubs and plants in the preceding summer/fall. I've even taken it upon myself to monitor roadkill anomalies in the fall, wondering if increased (decreased) animal activity in the fall may indicate a more (less) intense winter ahead, hence the above normal (below normal) roadkill sightings.
The unfortunate truth is that we don't know if these methods work, and likely will never know. The concept is very similar to us as a human race. We monitor certain trees and animals for signs of oddity, but that's like monitoring a certain person for an oddity. It doesn't work, because each person is different than the person next to them. As a race, humanity is quite similar across the board. The same goes with certain species of trees, animals, etc. But we can't observe a few trees and/or animals and make a qualified deduction from it. In order to determine any possible connection between nature anomalies and winter, a large-scale (covering a plethora of states) operation would likely be needed to monitor great masses of the same type of animal/tree, and then attempt to make a reasonable deduction on any winter prediction abilities.

Squirrels are commonly looked to for their ability to predict the upcoming winter, with observers monitoring a squirrel's effort to collect nuts earlier (or later) on in the year.

2. Six-Month Separation
This method involves monitoring conditions in June-July-August to see if conditions six months later (December-January-February) are correlated. The method likely stems from the question of cyclical patterns repeating on a regular, monthly scale; in this case, half a year. One might believe that Arctic 500mb heights in the summer may be related to Arctic 500mb heights that following winter, or the same scenario, except over North America, etc.
The truth behind this method is that it does not work a heavy majority of the time. I did some research last winter, where I compared monthly Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and Pacific-North American (PNA) index values from June-July-August to values for the following December-January-February to determine any correlation. Although I no longer have the exact values with me, I can recall there being little to no correlation between any of the indices' summer and winter values. Looking back, I believe the PNA actually ended up seeing a near-perfect split of 50% of years recording a positive summer PNA and negative winter PNA, and 50% of years recording a positive summer PNA and positive winter PNA, or negative rather than positive for both timeframes. The Arctic Oscillation may have had the "highest" anomaly, with the split coming in at 40%-60% when comparing number of years with positive summer/winter value correlations and negative summer/winter value correlations. To make a long story short, this method is not one worth using.

So far, we've discussed items that either don't work in long range forecasting, or their effectiveness has gone undetermined. Let's now go over some items that do have merit in the long range forecasting field.

3. Sea Surface Temperature Anomalies
Long range forecasters often look to the oceans for their outlooks. Multiple oscillations reside in oceans all around the world, with many of them spreading their impacts on a global scale. Forecasters tend to believe that these long-term oscillations, which may remain in their same state for months or years at a time, can predict winter conditions as far out as summer.
There is definitely some truth to this claim. Persistent SST anomalies in a certain part of the globe can allow forecasters to get a glimpse at the weather for multiple months ahead. Long-term oscillations, like the Pacific Decadal Oscillation (PDO) or Atlantic-Multidecadal Oscillation (AMO), can remain in their same positive or negative phase for years, or even decades, at a time. Some shorter-term oscillations, like the El Nino-Southern Oscillation (ENSO) phenomenon, can still allow for long range outlooks, valid for months in advance.

SST anomalies are often believed to be one of the best & most reliable predictors of long range weather.

4. Soil Moisture & Drought
This theory stems from the concept of feedback loops, which entail that something already in a bad situation gets continually worse, because that something is harming the things trying to improve the situation. In our case, we can apply this to drought. If a drought forms, the soil is anomalously below-normal in soil moisture, making the earth dry. As a result, clouds cannot form, meaning rain cannot fall. This makes the drought worse, and makes for a vicious cycle that continues the drought. Storm systems that move over the drought-affected region cannot produce as much rain as in other regions, because the storm can't draw water from the dry soil. Similarly, areas with above normal soil moisture may see rain continue, as more moisture is available in the soil than is necessary. Thus, the air becomes unusually humid, and any storms that form over this region can produce heavy rainfall, keeping the soil on a wet level.
This method of forecasting is more of a hit-or-miss method. This is because, while the theory of these feedback loops is sound (to an extent), a plethora of external forces, made up of oscillations in the oceans and upper atmosphere, can shift and change to bring rain to drought areas, or deprive precipitation to rain-soaked land. The atmosphere is one big, constantly-changing chess board, if you will, and some pieces happen to be weaker than others. While this drought/soil moisture method of long range forecasting can work, other factors must be taken into account as well.

We've only reviewed a few of many long range patterns known in the world of weather, but hopefully this gives you an understanding of some aspects of long range forecasting. While some methods don't tend to work well, others have experienced a decent amount of success. The hunt for a long range predictor with considerable accuracy will continue into the foreseeable future.

Andrew

Long Range Models Likely Incorrect in Winter Outlooks

After extensive analysis of multiple long range climate models, it looks like the consensus is for a moderate to strong El Nino on all guidance members, something that is not expected to occur, and thus rendering their forecasts incorrect.

NMME/CPC

The image above shows sea surface temperature anomaly forecasts from eight different long range models, all valid for the month of August 2014. These forecasts were made in July 2014, meaning this is only the first month forecast. Even though it's only one month out, we still see incredible inconsistencies. Starting along the top row, the CFSv2 model has warmer than normal SST anomalies persisting to the north and south of the Equator, with neutral anomalies along the Equator itself. This is a reasonable scenario, and we will examine this model further later on in this post. The CMC1 model allows a moderate to strong El Nino to develop, projecting SST anomalies of 1º to 2º C above normal (dark red) to form. Closer analysis indicates anomalies of over 2º C are actually present, seen in the dark brown. Checking out the CMC2 model, a relative of the CMC1, we still see moderate to strong El Nino conditions present per the SST anomalies, something highly unlikely to happen in the next ~25 days. Lastly, analyzing the GFDL_FLOR model, we once again find well above normal anomalies present along nearly the entire Equatorial Pacific region, from Ecuador to Australia. Aside from the well above normal anomalies, full-basin coverage of the El Nino is not anticipated, further degrading this model's credibility. Out of the four top-row models, only the CFSv2 model seems somewhat reasonable right now, and even that assertion is debatable.

Moving on to the bottom row, we come upon the GFDL model, a close relative of the GFDL_FLOR model. As such, the GFDL model continues the above normal sea surface temperature anomaly trend, though not as intense as many of the top-row guidance. This makes me think the GFDL may be on to something worth watching, and this will be discussed later on in the post. The NCAR model initiates a likely-Strong El Nino in the next couple weeks, something that will not be happening. The NCAR_CCSM4 model follows up with a nearly-identical scenario, so we can toss that solution as well. Lastly, the NASA model shows a moderate El Nino in place for the month of August. Because it's not such an extreme solution, we'll go over it further down the road.

After analyzing these models, we have found three of the eight models - CFSv2, GFDL, and NASA - to have somewhat reasonable scenarios. That means only ~38% of these forecasts have a chance to verify. Think about that- over half of these models can't even get the forecast right in the first month. It's pitiful, to some degree, but that's why we have scientists working to improve them.

Let's now analyze a sea surface temperature anomaly forecast for 3 months out, rather than 1 month out, to see how well our three aforementioned models are doing.

NMME/CPC

Let's now analyze the CFSv2 model in the top-left corner. In the forecast month of October, the CFSv2 has a Central Pacific-based moderate El Nino, possibly nearing Strong El Nino-strength. Unfortunately, considering conditions seem favorable more for a weak El Nino (MAYBE up to a moderate El Nino), we'll have to toss this forecast model.

Analyzing our second chosen climate model, the GFDL, brings about mixed results. On one hand, we see the forecast for a likely-moderate strength El Nino, something not too far from the realm of possibility. However, the El Nino is based in the west-central Pacific, something not showing up on other forecast models. For that reason, it may be wise to toss this forecast model as well.

Our last model of hope, the NASA model, shows unfortunate circumstances for October 2014. The model induces a moderate to strong El Nino across nearly the entire Pacific basin, something highly unlikely to happen. We can discount this forecast, too. Even lightly auditing the first-month forecast models can't save our chosen three models from the poor forecast ability just three months out.

Why do I think this is important? Many long range guidance models are calling for a warm United States winter, possibly accompanied by a cool South Plains at times. However, when you look at the SST forecast, it becomes apparent that the forecast cannot be trusted, due to a very slim chance of the SST anomaly outlook actually verifying. Thus, don't take the predominantly warm forecasts as they are unless verifying the SST outlook; the same goes for predominantly cold winter outlooks, as their SST forecasts must be verified as well.

Andrew

Weak El Nino Preparing to Surface; Atmosphere Not Responding

The warm water anomalies in the central Pacific look to be pushing towards the surface, possibly inducing the expected weak El Nino for this fall and winter.

CPC
Refresh the page if animation stops looping

The animation above shows water temperature anomalies along the Equator, on a depth-longitude graph. We can see the extremely above-normal waters pushing into the surface earlier this summer, a byproduct of the Kelvin Wave that traversed the Pacific during this past spring. After the warm waters dissipated, we saw a swath of below-normal water temperatures take over. This put us back to the same neutral-ENSO / Cool-Neutral ENSO situation we've been in for the past couple of years. Fast-forward to the present, and we see a new situation developing.

Warm water anomalies have been steadily building underwater around the Central Pacific region, between about 100 to 200 meters below the surface. These waters have been organizing themselves in recent days and weeks, and the eastern-most portion of these positive anomalies has begun shifting towards the surface, and towards the east. It is currently expected that these warm waters will push east and eat away at the below-normal water temperatures. If the warmth can sustain itself and hit the surface, this should be our weak El Nino, possibly more towards a moderate El Nino at best.

NOAA

In order to actually see an El Nino develop, however, we'll need to see the atmosphere respond, which isn't happening just yet. Shown above are two panels; one shows the mean surface wind currents across the Equatorial Pacific, while the bottom one displays anomalous wind currents. In order for the atmosphere to indicate an El Nino is present, we would have to see winds going from west to east, as part of the reversed Walker Circulation, which is displayed below in the form of the regular circulation.

BOM
Switch wind direction  and warm/cool anomalies' places to observe reversed (El Nino) Walker Circulation.

In the Walker Circulation, surface winds go east-to-west, where the air rises due to convection near Australia. Upper-level winds then push west-to-east, before sinking near the South America coastline, completing the circulation. This is commonly seen in a La Nina event. The El Nino reverses the Walker Circulation, where surface winds push west-to-east, allowing convection to develop along the coast of South America. Upper level winds are carried westward, before sinking near Australia.

If we look back at the surface wind current image above, we can see the winds along the Equator pushing predominantly to the west, indicating that the atmosphere is not favorable for an El Nino. We have yet to see if this will change in coming months, and if it may allow for an El Nino to actually establish itself.

Andrew

Notice

After some thinking and analyzation of where the blog is at now, I've decided to go ahead and enlist advertising for The Weather Centre. These adverts will be placed on the sidebar of the blog only, so as not to disrupt the environment of the blog.

I decided to enlist advertising to benefit the blog, and all of you. If I am lucky enough to collect any substantial revenue from these ads, I hope to invest in products to improve the blog's experience. Such investments may include paid model subscriptions, enhanced radar software, and other ventures.

These ads are not meant to be a big source of revenue for me- that's not my intention, at all. These ads are only meant to better the blog as a whole.

Unfortunately, I cannot control the majority of ads that appear on the blog, so I apologize in advance if any are not related to the website, may be controversial, or are just "odd", for lack of a better term.

If you have any concerns or suggestions on these ads, please don't hesitate to voice them, since, at least from my point of view, this may be a rather controversial move.

Andrew

Arctic Sea Ice, Temperatures Indicative of Winter Ahead

Latest observations of Arctic sea ice anomalies, as well as temperature anomalies, may hint at what's to come this winter.

COI

The above graph shows past records of Arctic sea ice over time, categorized by color, with the key on the bottom left. This year's sea ice observations are shown in the thick black line, while 2013's sea ice observations can be viewed by the orange-colored line. Glancing around this chart, it's quite evident that sea ice anomalies in comparison to recent history are above normal this year. Showing itself more recently, these above-normal sea ice anomalies appear to be eclipsing the observations of 2006, which appears to be the highest areal sea ice coverage minimum in the last ten or so years. This recent slowdown of declining ice coverage indicates the presence of cold air over the Arctic Circle, something that stays in that area year-round. What's more important this time, however, is that the cold air is allowing less ice to melt, which in response provides more cold air, and so on and so forth.

COI

The next chart we will analyze is a graph of observed temperatures in the Arctic Circle. The red line on this graph shows observed temperatures, in units of Kelvin. The green line indicates the average temperature for a given date, and the solid blue line depicts the freezing temperature. Arctic temperatures have remained almost completely below average since this spring, a rather remarkable feat. Temperatures currently are above freezing, as is to be expected for the summer season, but observed temperatures remains below the average temperatures. As we discussed earlier, the presence of cold air and slowing of sea ice melt are likely playing into these below normal temperatures in the Arctic.

To break it all down, these developments tell me the chances of a cold winter ahead are being raised. If we were to see low sea ice levels and warm Arctic temperatures, I'd probably root for a warm winter ahead. However, seeing substantial sea ice presence in the northern Hemisphere, as well as consistently below-normal Arctic temperatures, I believe that these factors could play into the risk of another cold winter ahead.

Andrew