Snow cover growth continues over Eurasia and over the last several days the spread of the sea ice in the arctic has increased rather rapidly. So far through the first half of October the snow cover growth was rather tepid and behind the rate of growth of the prior 2 winters however we have seen a pick up in the last 4 to 5 days over the area in general.
Just to review, it is the rate of growth of the snow cover and not necessarily the depth of snowcover that is important. It also is where we finish the month and not where we started or where we are in the middle of the month. 6 days remain in October so By this time next week we should start seeing what the growth rate indexes are showing and make some kind of determination of what it means for the upcoming winter.
This is the GFS snowfall forecast for the next 6 days ending Saturday 10/31/2015 8PM and I think the important thing to focus on is the area between 50N and 60N. We don’t care very much about what falls north of 60. Snow lovers will want to see a continued expansion of the Southern and Western Flanks. As I recall last year the rate of growth slowed some around mid month before there was an end of month burst of snow cover growth.
Now remember this is one indicator. Also remember that the result of last year caused those who follow this closely to conclude certain atmospheric changes would occur that would result in a harsh winter. Namely the forecast was for the development of high latitude blocking which never happened. Instead the main driver of last winter (and the winter before) was the warm water off the northeast Pacific to the Gulf of Alaska. So many said they got the forecast right but for the wrong reason. Also the cold did not extend geographically to other areas of the east and midwest like it did the winter before. Here are the indicators that I am paying attention to over the coming weeks.
- El Nino which remains strong through there are some indications that the peak is close or may have occurred in recent weeks however the situation is fluid. Note the Climate Prediction Center is forecasting El Nino to continue through the winter which coincides with their winter forecast. That forecast was completely el-nino based.
- Warm Ocean waters continue off the Pacific Northeast Coast into the Gulf of Alaska. This was the driver of the last 2 winters. This anomaly was not present during the 1997-98 el nino nor was it present during the 1982-83 el nino.
- From the same map above is the expanding cold pool of ocean water south of Greenland. That area seems to have grown over the last number of weeks.
- Negative values for the Atlantic Oscillation and North Atlantic Oscillation which have persisted for the most part all summer and into the fall. This factor would favor colder than normal air into the east.
There are several other factors which may also come into play including the robust snow growth that has occured in Eastern Canada this year. I went back and tried to find some sort of link but this seems to be a variable that may not have much impact. It was hard to make a connection between early fast snow cover growth in Eastern Canada and winters in the east.
I have never been a fan of seasonal forecasts and certainly the winter forecasts from the Climate Prediction Center in my view continue to really say nothing of value. They missed the last 2 winters and in fact they have not predicted below normal temperatures in the northeast of east anytime in the 15 winters. Equal chances really doesn’t tell me anything. Snow lovers need to understand that for many areas 6 of the last 7 winters have produced normal or above normal snowfall and that doesn’t happen very much if at all. A below normal snowfall winter in the northeast would not be a surprise if it happens. On the other hand we have been in a general 15 year up cycle that began in 2000 so if this is going to be 7 of 8, you have that up cycle in your favor. I do believe that even if El nino remains strong all winter long, the North Atlantic Oscillation and the Atlantic Oscillation will be a player this winter unlike the last 2 which will make things interesting for at least a couple of big threats along the way.
JOESTRADAMUS will probably make some sort of winter prediction in the next week to 10 days so stay tuned. I have given some hints here as to what I am thinking and where my mind is going with regards to winter 2015-2016.