Winter Recap : 2018-2019 Winter in Review

As we begin to look at the coming 2019-2020 winter, and speculate what awaits, lets take a look back at last winter… to see what actually occurred, as well as what we speculated would happen.

First, let’s start with our 18-19 Winter Outlook temperature projection:

We had projected below average temperatures in the SE half of the country, and above average temperatures in the NW half of the US.  So lets take a look and see what actually happened…

Well… that’s kind of the opposite.  Warm where it was supposed to be cold, and cold where we expected to see warmth.  The winter actually started out as expected, with October, November and December, all looking the way we expected.  Then things went off the rails in January, and we never got back to what was expected.  So lets try and figure out where the outlook went wrong.

First, lets review what our sea surface conditions were projected to be in our winter outlook…

We had expected a weak El nino (A) and warmer water right along the US coast, with cooler water expected back toward Hawaii.  Now lets see what actually occurred…

The area near (A) turned out right, with a weak El Nino.  But the conditions near area (B) the Northeast Pacific Ocean, is where things didn’t go as planned.  The differences may not appear dramatic, but they were enough to result in almost the inverse of the winter we expected.  We circled 2 areas in the Pacific.  The blue circle shows well above average temperatures in the ocean, but if you look at the projection, waters were expected to be cooler than average in that area.  Looking to the brown circle, the sea surface was near to slightly below average… which is close to what the outlook had projected.  But it’s the combination of the two circles that we think caused the outlook to bust.

Having the warmer pool of water (blue circle) off to the west of the cooler water (brown circle), while subtle, is the opposite of what we had projected.  Here was the upper air pattern (jet stream) we had projected for last winter…

Here’s the ACTUAL upper air (jet stream) pattern that occurred last winter…

The pattern is almost opposite of what we projected… and our contention is that the warmer water NW of Hawaii and the cooler water to the east are the culprit.  The warmer water influences a sustained ridge of high pressure, which is what we got over Hawaii, instead of the western US.  The cooler water east of Hawaii favored a dip in the jet stream and a persistent trough out west.  All of that leads to a reflexive ridge in the eastern US, leaving us milder than average.  This is why we believe the pattern of the oceans is so important, because it’s not just the temperatures themselves… it’s how different regions relate to the surrounding waters.  But ultimately… seasonal forecasting is an imperfect science.

Could We Have Done Better?

Of course we could have… because the outlook was nearly inverse of the result.  But it’s important to remember, the winter outlook is built on assumptions made by computer models.  When we create the outlook, we know what the current SST profile looks like, but we utilize computer data to estimate what the sea surface temperatures (SSTs) will look like in the coming winter.  Most times, it’s close, or similar to what the current conditions are.  However, if the actual SSTs end up being drastically different than the projected SSTs from the Winter Outlook… odds are, the outlook will be a bust.

So when asking if we could do better, the question really is, did the data give us clues that we might have missed?  The answer to this question… is yes.

Remember, this is what the actual SSTs looked like.  Notice the areas circled… lets compare the result, to the 2 computer models used…

This is actually quite interesting.  Going back and reviewing this… we were rather shocked to see the exact pattern that resulted last winter, in each of the model data.  Both the CFSv2 and JAMSTEC have the cooler waters to the east of the warmer waters in this key part of the world.  This pattern would favor the dip in the jet out west, and the reflexive ridge over the southeast.  It gives us pause as to how we did not give this more credence in the winter outlook last year.  Was it a blind spot, or did we believe the cooler water east of Hawaii was too small and insignificant to make a difference?  We’re not sure… but it’s very interesting for sure.  Something we’ll be alert to when finalizing this year’s outlook, and beyond.

But in closing… we love putting together the winter outlook each year.  It’s a complex look at multiple factors that will hopefully give us a preview of what the coming winter will hold.  Clearly, as we always try to reiterate, it’s nearly 50% forecast, 50% entertainment… just because of the combination of forecasting 3 to 6 months into the future, and relying heavily on computer data to do it.  But with that said, we’re always trying to fine tune our methods and learn from our mistakes.  If we can eliminate as many blind spots as possible, we can give the most accurate outlook possible.  Hopefully you’ve enjoyed this review of last winter’s outlook, as we prepare for the release of the 19-20 winter outlook.   Thank you for all your support!

 

4 thoughts on “Winter Recap : 2018-2019 Winter in Review

  1. Predicting the weather is not an exact science. But learning the methodology behind these predictions is amazing. HVW puts science in layman’s terms. I’m thoroughly enjoying my sneak peeks-carry on sirs!

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