After looking over the latest data on the ENSO cycle, the MJO, NAO, PNA teleconnections, and throwing in a little bit of experience and gut feeling, I have made a few edits to the winter outlook for Kentucky. I also added a tidbit about possibilities for spring 2016. This will be the final revision.
Updated outlook:
I can’t believe it but 2015 is winding down now. We are into the last quarter of the
year. The deciduous trees are beginning
to change colors and drop their leaves.
The air is getting cooler. The
sun’s angle is waning. The nights are
getting longer. We're turning the clocks back this weekend. And with that, those of
us who dwell in the mid latitudes of the northern hemisphere are turning our
minds toward winter.
That begs the question; what will winter 2015-2016 be like
in Kentucky? Are we in for another harsh
one with sub-zero January cold and frequent snowfall? Or is this winter going to begin a pattern of
milder winters that will carry us for a while?
I suppose this would be a great place to insert my
disclaimer. Obviously nobody except God
himself knows for a fact what is coming, and even with all the technology we
have today and the supercomputer power we have to run our models on, seasonal
forecasting has still proven to be a very difficult task with little
accuracy. It is virtually impossible to predict
a white Christmas, for example, from this stage in the autumn season. Having said that, we can look at the global pattern, history, and computer data and come
up with at least a ballpark idea of what to expect in the December-February
time frame. And that's the point of a winter outlook... to give folks an idea of the general type of winter we may be in store for.
Here is how I see the winter of 2015-2016 to play out in
fairly simple terms: it’ll be more variable this season with more swings in
temperatures and a lesser number of snow events but a higher possibility of a
“big one” compared to average. In other words, I do not think we will see as much snow as we've seen in the past few winters, but due to the wild swings in the pattern what snow we do see may come in the form of larger storms. Overall, I expect temperatures to be milder than what we've seen in recent winters.
Now, to expand on those thoughts a little more for those of
you who are still interested…
El Nino is going to be a big deal this winter. We haven’t dealt with El Nino in the past
three winters. In fact, ENSO conditions
have been fairly neutral going into at least the past two winters. So the temperature of the Pacific Ocean water
hasn’t really come into play regarding our winter weather here in Kentucky in
recent years. Other factors such as
blocking patterns in the higher latitudes and the persistence of a mean trough
in the eastern U.S. were responsible for the cold and snowy weather we saw last
winter and the winter before that also.
That is all going to change for this year. El Nino conditions are already present and
are already strong and are predicted to get a little stronger over the next
month or two before peaking. In fact, a
look at the latest model predictions shows that an event peaking above 2.5°C
from average is very possible.
That
hasn’t happened since the late 1990s. So
what’s going on out in the Pacific waters is going to be a huge factor in the
winter weather here in Kentucky this year.
This is true because our weather comes from the west. The Pacific is sort of the “breeding ground”
of our storm systems. Warmer water
generates more action (hence all the hurricanes nearly striking Hawaii this
year and hurricane Patricia which set the record for hurricane strength in the eastern Pacific). As a result, you normally will
see wetter than average conditions east of this area which includes the
southern tier of the United States during a strong El Nino. I think there will be storm systems coming
out of the southern part of the country more frequently this year, and it’s
those “southern runners” that can result in big snow storms for Kentucky. That’s why I said I feel like the chances of
a “big one” are higher this season compared to average.
However, to make a big snow storm you need another
ingredient: cold air. One of the things
that El Nino tends to do (and we saw this in the late 1990s) is that it can
create a pattern where temperatures are mild across much of the U.S. When I was a meteorology student at WKU I
remember walking to classes in a t-shirt all the way through final exams before
Christmas. After the holiday break we
had some mild weather as well. So this
is why I said that I feel like snowfall will be less frequent this year than
the past two years. We will likely see
quite a few cold rain events this winter.
It’s going to take perfect timing of a cold air mass being in place
while a strong weather system moves up from the south to make the magic
happen. Hence, less chance for snow
events, but a bigger chance for a BIG snow event IF one does happen.
I think the theme of this winter overall is going to be
summed up in one word: variable. Whereas
the winters of the last several years were just flat out cold (record setting
cold at times), I think this winter will be more variable with periods of cold,
but periods of mild weather as well. Having said that, I think the mild weather will win out and average temperatures will be at or above normal. Keep in mind that the term "mild winter" doesn't mean that it never gets cold. It just means that compared to average, it's warmer than normal. In
terms of sky conditions I expect sunny days to mix more often with rainy ones. The occasional snow event will be with us,
and as already mentioned the chance of a big one if things come together just right once or twice. But overall I think we’ll get a good mix of
weather this season. I think this will
happen due to the strong influence of El Nino lasting throughout the winter,
and the smaller influences of teleconnections like the PNA, NAO, etc. aligning
from time to time to alter our weather for a week or two at a time. If we can get the PNA to go strongly
positive, the NAO to go strongly negative at the same time, and this warm El
Nino water to kick out some weather systems all simultaneously…look out! The superstorm of February 1998 comes to mind. But it will all have to come together
perfectly to make that happen. Time will
tell if we’ll see that or not. For now,
enjoy this warm weather and lower energy bills that are coming over the next
several weeks courtesy of our buddy El Nino. In fact, the first week of November looks to be a very warm one with some record high temperatures possibly in jeopardy.
So to summarize:
Temperatures – Average to slightly above average overall,
occasional cold snaps, but overall a milder winter than what we've seen in recent years.
Precipitation – Average to slightly above average with more
rain and the possibility of a couple of severe thunderstorm outbreaks. Snow will be less frequent, but there will be the possibility of a big snow storm at some point if timing aligns just right.
Keep in mind that severe weather can and sometimes does occur in winter here in KY, particularly in these types of patterns. And that will also be something that we'll have to watch closely from March-May 2016 because many times we do see a large increase in severe weather outbreaks following these El Nino years.
So there you have it. I have often said that harsh winters strike KY every other decade. The 1950s, 70s, and 90s all featured terrible winters, and so I expected the '10s to give us some harsh ones and the 2012-2015 period proved to do just that. I think this winter our utility bills will be a little lower than what we've been seeing.
Keep in mind that severe weather can and sometimes does occur in winter here in KY, particularly in these types of patterns. And that will also be something that we'll have to watch closely from March-May 2016 because many times we do see a large increase in severe weather outbreaks following these El Nino years.
So there you have it. I have often said that harsh winters strike KY every other decade. The 1950s, 70s, and 90s all featured terrible winters, and so I expected the '10s to give us some harsh ones and the 2012-2015 period proved to do just that. I think this winter our utility bills will be a little lower than what we've been seeing.
-Shawn
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