This year’s winter outlook once again took many hours of research and many factors were considered. Unlike last year when we had a La Nina in the Pacific Ocean, this year we will have a weak to very weak El Nino. Here's just a small part of the items I considered this year and how I think they will play out with our winter of 2012-2013. El Nino: When looking at the El Nino, you must look at how strong it is, when will it peak, how fast will it fade and where in the Pacific Ocean is it strongest. This year's El Nino is forecast to be weak to neutral. Here's a chart of the forecast of the El Nino and as you can see it is forecast to stay weak at best.
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Transcript
This year’s winter outlook once again took many hours of research and many factors were
considered. Unlike last year when we had a La Nina in the Pacific Ocean, this year we will have a
weak to very weak El Nino. Here's just a small part of the items I considered this year and how I think
they will play out with our winter of 2012-2013.
El Nino: When looking at the El Nino, you must look at how strong it is, when will it peak, how fast
will it fade and where in the Pacific Ocean is it strongest. This year's El Nino is forecast to be weak to
neutral. Here's a chart of the forecast of the El Nino and as you can see it is forecast to stay weak at
best.
Pacific Decadal Oscillation ( PDO ): I'm a firm believer in the Pacific Ocean having a major impact
on our winter weather. Let's face it, oceans cover about 3/4 of the earth so we must pay close attention
to what certain ocean currents and sea surface temperatures are worldwide when doing long term
seasonal forecasts. This oscillation as the name implies, tends to last for a decade or longer, actually
around 20 - 25 years. We were in the "cool" phase of the PDO from about the middle 1940's till the
late 1970's. We then went into the "warm" phase of this oscillation from the late 1970's until about
2000. Since around 2000, we have gone back into the "cool" phase and this had to be factored in when
looking at the El Nino. El Ninos of the 80s and 90s will not act the same as current El Ninos because
of the change in the PDO. I believe this is going to keep us in colder winters for probably the next 10-
15 years. To give you an example, during the decade of the ‘90s all our winters were above
normal. Since 2000, we’ve had 12 winters and 8 of those have been colder than normal. There’s an
obvious change that has happened since 2000.
Here's a graph of the PDO trends since 1900:
Atlantic Ocean and Gulf of Mexico temperature profiles: Depending on what the temperature
profiles look like in these areas will help determine where storms may be more likely to form and
where the will track. Will a high pressure be more likely to form in the southeast or will low pressure
be more likely there during the winter, this can greatly impact temperatures and storm tracks for us in
this area. This year it does not look favorable for a “ridge” of high pressure to set up over the southeast
part of the country for any long period of time. In the graphic below notice lots of warm water in the
Gulf of Mexico and in the Atlantic. The cool area off the southeast coast was colder water churned up
by hurricane Sandy in late October.
North Atlantic Oscillation ( NAO ): Just like the PDO, this also will oscillate but on a much shorter
time period. The NAO is very difficult to predict much more than a couple of weeks in general and
then it's not always predicted well. When the NAO goes into a negative value, we generally have
colder than normal temperatures and when it's positive, we normally have warmer than normal
weather. The NAO has been mainly running mainly negative the past few months ( it was positive
much of last winter ) so the question here is, will that trend continue. My feeling is that we will remain
in a negative phase much of the time but there will be swings to positive and this will give us some
pretty large temperature swings from cold to warm.
Here's the NAO chart since 1950. Notice the very positive values for last winter but very negative for
the two winters before that and those winters were cold.
Arctic Oscillation ( AO ): This works similar to the NAO and when negative, we have colder weather
and positive brings warmer weather. It was running mainly positive until around October 1st and then
went negative and stayed there for the entire month and we ended October 3 degrees colder than
normal. It has been bouncing around the last few weeks as you can see from the chart. Once again, I
think we are looking at mainly a neutral to negative value here. When the AO and NAO are both
negative, we should experience some pretty cold weather and look for that for some of the winter.
Atlantic Multidecadal Oscillation (AMO) This is based on the sea surface temperatures mainly in
the northern Atlantic Ocean. It’s currently in the “warm phase” and is running the warmest we’ve seen
since back in the 1950s. We are still learning about the AMO but we tend to see more of a “blocking”
pattern when it’s in the warm phase and this brings shots of colder weather into the eastern part of the