
The Official Forecast of the U.S. Government Never Saw This Winter Coming - Shivetya
http://www.businessweek.com/articles/2014-02-18/the-official-forecast-of-the-u-dot-s-dot-government-never-saw-this-winter-coming
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nateweiss
FWIW, my next-door neighbors, who were dairy farmers for many years, felt
quite certain that it would be a very harsh winter this year. Their prediction
was based on a few natural indicators: the fact that old apple trees along our
road were bearing fruit for the first time in a while; and the coloring of a
certain type of furry caterpillar (sadly, like a typical city transplant, I
don't recall the details at the moment). There was also something about where
birds were placing their nests.

My lovely neighbors are full of observations and predictions like this,
sometimes preceded by references to the Farmer's Almanac... what one could
call "country wisdom" with perhaps a smile on one's face... but it really
seems like they are usually right about such matters. They were so convinced
of the harsh 2013-2014 winter that they decided to leave for two months of it,
which they haven't done in like 50 years or something--which turned out to be
a great call. Of course it could be coincidence or random chance, and I
probably don't hear about or remember the times when the predictions are
wrong. But I do love that there are other constructs for measuring and
predicting weather other than what we typically hear about from the
weatherperson on the news.

~~~
ackydoodles
Your lovely neighbours cannot be correct except by chance; if there was any
validity to their predictions, it would imply not just that they knew the
future of the weather, but that the future of the weather was knowable, which
it certainly is not. Your tendency to see their predictions as accurate is
likely a conflation of your confirmation bias and your choice-supportive bias.

Humans naturally search for meaning in chaos. That is all that their
observations of caterpillars and trees and birds amounts to. They are trying
to attach significance to a chaotic universe in order to reassure themselves
that their place in the world makes sense. It does not. This is mathematically
verifiable.

If the birds and the caterpillars and the apple trees could know the future of
chaotic systems, it would imply that we live in a deterministic universe where
birds and caterpillars and apple trees could not exist. QED.

~~~
dllthomas
_" If the birds and the caterpillars and the apple trees could know the future
of chaotic systems, it would imply that we live in a deterministic universe
where birds and caterpillars and apple trees could not exist. QED."_

Wut?

~~~
ackydoodles
Complex dynamics 101: life is a complex dynamical system. If the math of chaos
is wrong, the processes underlying life would not operate as they do. Life
would not exist as we observe it.

Also, your iPad would not work. As I said, QED. This is not controversial.

~~~
Oletros
> Also, your iPad would not work.

What?

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Oletros
Reading the comments is a really depressing exercise.

Do people really know the difference between weather and climate?

~~~
jerf
I'm increasingly less impressed by the claim that we can't predict weather
across weeks, but we can somehow predict climate across decades. (I've never
been overwhelmed by it, but it seems even less sensible over time.) And part
of the reason why is that we can't seem to predict climate across years, and
I'm _really_ unconvinced we can't predict climate across years but we can
predict it across decades.

Wrong predictions are wrong predictions; it is irrational to keep excusing
wrong predictions over and over again and insisting they'll just get more
right in the unknowable future.

If the models can't look into the future even a few months and see a high
probability of the vortex detaching (and I'm _fine_ with a probabilistic
prediction, in fact I'm deeply suspicious of anything else), what use are they
for predicting anything else? One wonders if the models are even capable of
expressing that prediction (in the machine learning sense of the word "bias").

~~~
rayiner
That predicting behavior at larger scales is easier than predicting it at
small scales is a principle you'll encounter repeatedly in the physical
science and engineering disciplines. In the physical sciences, models are
often top-down, as opposed to in computing where they are almost always
bottom-up. In fluid dynamics, for example, the behavior air in a turbulent
flow is chaotic at the small scale. Yet, we can still design airplane wings
because we have pretty good approximate models for how such flows behave at
larger scales. Or to use a physics example: it's easy to predict where a
baseball will land, but very complicated to predict where an electron will be
in a molecule.

~~~
scott_s
The analogy I like to think of is a ping-pong ball in the ocean. At any given
second, its location will be hard to predict, as at the second-granularity,
its location will be dominated by local phenomenon. But, over the course of
months and years, we can often accurately predict where it will generally end
up in the world due to ocean currents.

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ck2
So are polar vortex dips now going to become a regular thing?

Because I could see rock salt becoming a valuable commodity (ironically
returning us to roman times?)

What is all that salt and brine doing to wildlife and water tables?

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drpgq
I liked Nate Silver's chapter on climate modeling predictions in his book The
Signal and the Noise. He wasn't impressed. Maybe somebody needs to start a
fantasy weather league.

~~~
TheCraiggers
The hilarious ending of course would be the fantasy weather league correctly
predicting the weather.

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d23
That scroll is obnoxious. You shouldn't suddenly jar the text position out
from under the reader's eyes.

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ackydoodles
That is because the weather is a chaotic system. It is governed by the
mathematics of complex dynamics.

Predictions diminish in accuracy with increasing time because the number of
inputs rapidly approaches infinity, and each one of them can turn out to be
determinative of the overall behaviour of the system.

It should be no surprise to any scientifically literate person that a weather
forecast issued in October has no validity by January. Any resemblance to
reality is purely accounted for by chance.

This is not amenable to the Mr. Fix-It mentality that inevitably shows up in
these discussions. There is good reason to believe that weather prediction
will _never_ improve, no matter what the scientific and technological
developments, because the future of a chaotic system is mathematically
intractable and genuinely unknowable.

The same argument applies to climate science. I'm sorry to bring you the very
bad news that we live in a chaotic universe, not a deterministic one. Get over
it. Wear a helmet.

Edit: The mysterious part is that the scientists at the so-called Climate
Prediction Center would issue a 3-month forecast. What part of complex
dynamics did they not understand? Sometimes an expert is just a guy with
slides.

~~~
sp332
Prediction centers might not be able to tell the exact date and place of a
storm that far out, but they can at least tell if a season is going to be bad
well ahead of time.

Edit: It says this right in the article: _climate forecasters focus on things
that change more slowly, such as temperatures of the land and oceans... they
try to say whether a given three-month period will be wetter, drier, hotter,
or colder than average._

~~~
ackydoodles
I'm sorry, what part of complex dynamics did _you_ not understand?

It doesn't matter how slowly things change. It doesn't matter how big the
inputs are. Complex dynamics teaches us that scale does not matter; very small
inputs can and do end up being more important than very large inputs.

I'll say it again: _scale does not matter_.

No, they cannot tell if a season is going bad well ahead of time. It is a
fallacy to think that they can. They can tell that a season is going bad
exactly at the moment the season starts to go bad.

Why is it that every time I raise the issue of the unknowable future of
chaotic systems that people down-vote me? Is it so hard for you to accept?
Check the math and the science: it is sound. I am sorry you do not like it,
but the mathematics of chaos is not some fringe idea. It underlies everything.
I'm astonished that so few people have noticed this.

~~~
sp332
Chaos theory does not mean that literally anything can happen. Weather changes
are still bounded by energy inputs and outputs. It can't rain if the humidity
in the air is too low. The jetstream isn't just going to reverse course
anytime soon, although it is shifting slowly. It's physically impossible to
have snow if the weather is too warm - complex dynamics can't change that. I'm
not saying a forecast will never be wrong, but not every case is an edge case.
With good data and a useful model, you can be right most of the time.

