Thursday, June 19, 2014

Global Sea Surface Temperatures Supporting Cold Winter Ahead

Global sea surface temperature anomalies continue to point towards an increased likelihood for a cold winter ahead.

There are four specific items I want to review that are pointing towards this cold winter idea.

1. El Nino
It's been discussed countless times already by countless weather agencies and enthusiasts, but we'll discuss it again here. The anomalously warm waters appearing west of Ecuador, nicknamed the El Nino phenomenon, look to be a crucial piece to this puzzle indicating a chilly winter ahead. In typical El Nino situations, we tend to see warm weather confined to the North and West US regions, while cool anomalies prevail in the South and East. Considering the El Nino retains the highest confidence for still being present in the coming winter, confidence in a cooler than normal winter for the aforementioned regions rises in response.

2. Cooler than Normal West Pacific 
This factor doesn't constitute an oscillation or index, per se, but will likely play into what we see happen this winter. The past cold season, I based the majority of my long range posts off of storms I was seeing hit Japan, based on the Typhoon Rule popularized by Joe Renken. It only takes a simple understanding of the relationship between high/low pressure patterns and sea surface anomalies to recognize what this means. The presence of below normal water temperatures extending eastward from Japan could very well mean that we see a stormy pattern over Japan this winter. Translating that through the Typhoon Rule, it means that the prospects of a stormy (and consequentially cooler) winter are enhanced.

3. Positive Water Temperature Anomalies in the Gulf of Alaska
In addition to the waters off Ecuador, the Gulf of Alaska is also experiencing above normal water temperatures. However, the placement of this particular body of warm water is key. Last winter, well above normal water temperature anomalies in the Northeast Pacific resulted in consistent high pressure along the West Coast, which provoked the polar vortex and incredibly cold air to push south, affecting much of the United States in the process. Barring any significant changes this summer and fall, a similar situation could unfold this next cold season.

4. AMO
The Atlantic Multidecadal Oscillation, abbreviated as AMO, is the wild card this winter. In recent months, it has reversed from its positive phase, which appears as warm waters along the coast of Greenland and into the Arctic Circle, into its negative phase, which features cold water temperatures in those same areas. The two conflicting masses of water are outlined clearly on the image above, and right now, it looks like the warm water is winning the fight. If it does hold out, we can expect increased probabilities of high pressure being sustained over Greenland, which would buckle the jet stream to the south and allow for cold air to penetrate deep into the Eastern US. Again, however, this is the wild card, and we likely won't know if this will happen for another handful of months.