Good morning everyone. Since we are currently experiencing excellent weather that will continue into the weekend I thought I would share a factor that goes into my winter forecasts, the ocean.
In order to make a contrast between the ocean temperatures in cold/stormy winters vs warm/non eventful winters I ran an analysis that subtracted the 10 most snowless winters from the 10 snowiest winters over the last 60 years. Here is the result..
What is most glaring in the image above is that in the winters that produced the most snowfall, you can see a distinct area of warmer than normal sea surface temperatures off the coast of California into gulf of Alaska. There is a reason for this as warmer water off the west coast tends to support a high pressure ridge that extends up into western Canada. The result is a downstream trough over the east coast. The image below shows this using the same difference in top 10 vs bottom 10 winters.
Notice the large dark blue area south of the Aleutian Islands and the orange area extending into Alaska and western Canada. This represents a tough and a ridge in the jet stream. The downstream effects of this are a deep trough over the eastern 1/3 of the country. As a reminder troughs cause colder and stormier conditions as they represent low pressure.
Although this is not the only factor when it comes to predicting a winter, you can see it is something that we need to keep a close eye on. Right now, here is what models are predicting for ocean temps for the winter of 2016..
For snow lovers out there you can see AT THIS TIME models are hinting that the warm water stays off the west coast. However, also notice the very warm water off the coast of South America in the tropical pacific. As I have discussed, this is EL Nino (click tab at top of page for more info) and that will also be a MAJOR factor when trying to put together a forecast. We simply do not know how all these variables will change over next 4-5 months so that is why its premature to try to make a forecast at this time. All we can do is study trends and identify the major drivers behind cold/warm winter weather. I am a firm believer ocean temps are one of them.
Stay tuned for more sneak peaks at other relevant factors. The actual Winter Forecast 2016 comes out in October.