MY FINAL WINTER FORECAST....

November 1, 2018

It's November and it's time to start getting serious about winter. I've mentioned on a number of occasions that I feel the two key drivers in this years version of winter will be a Modoki El Nino (centrally based in the Pacific) and abnormally warm sea surface temperatures in the Gulf of Alaska (the blob below).

Here's the latest forecast for the Modoki. It's very much in the weak category through the winter.

As most of you know the majority of Earth is comprised of water...71% to be exact. 96% of that resides in the oceans. That's why sea surface temperatures are so important. By knowing where the greatest anomalies exist we can get an idea of how jet stream patterns will set-up. That's key to temperatures, precipitation, and the overall type that falls.

 

With that in mind I went back and found October sea surface temperature analogs that included Modoki El Ninos and above normal Gulf of Alaska "blobs". The idea is to compare those sea surface temperatures to current ones to find links to the winter ahead. I came up with 5 years that are similar to 2018. They are 1993, 2003, 2004, 20013, and 2014. Here's the comparisons to 2018 SST's.

 

In Cedar Rapids the average temperatures for the following winter's (Dec.-Feb.) looked like this. 

 

1993-94.....19.9

2002-03.....24.9

2004-05.....27.3

2013-14.....15.4

2014-15.....22.4

 

The average winter temperature in those years comes out to 21.9 degrees. That's 2.8 degrees below the norm of 24.7. Here's a graphic with yearly plots compared to normal. 

Switching to snowfall I came up with this. I took seasonal measurements from November 1 to April 30.

 

1993-94.....30.6"

2002-03.....22.1"

2004-05.....22.5"

2013-14.....42.9"

2014-15.....24.1"

 

The average winter snowfall came out to 28.44". That's 0.9" below the long term norm of 29.3". The graphic below shows yearly plots compared to normal.

In summary, what the analogs show is that there is a strong chance winter temperatures end up below normal. The 2.8 degree average departure may not seem like much but it is significant. However, there is a large spread from 15.4 to 27.3 degrees in the 5 different analogs indicating room for variability.

 

Outside of the one winter with 42.9", snowfall was generally below normal. The analogs would point to near or below normal snowfall in the coming winter. Based on the analogs I would estimate 25-30".

 

That said, if you really drill down, the best SST comparison of the 5 analogs just might be 2013-14. Running with that temperatures would end up 9.3 below normal and snowfall 13.6" above. That would be a tough winter and in my opinion the worst case scenario.

 

The 2nd best analog might be 2004-05. Using that temperatures would end up 2.6 degrees above normal and snow would be about 6" below. To me this is a best case scenario and I think the odds are against it.

 

I like the compromise between the two extreme solutions so I'm sticking with below normal temperatures and near normal snowfall in my local area.

 

Anyway, the point of this exercise is to show that I just don't throw out forecasts without thinking about them. This is a scientifically based outlook. Even so, mother nature always has a few twists of her own and despite my best efforts, I can't guarantee the results of my research. Just know that I put plenty of thought into this winter forecast and I feel good about it. Roll weather...TS

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© 2019 Terry Swails