Thursday, August 14, 2014

Sea of Japan Rapidly Cooling; Winter Implications Possible

The Sea of Japan has experienced rapid cooling in recent days, something that could come into play later on this winter.

The image above, recorded on August 4th, 2014, shows sea surface temperature anomalies across the Pacific Ocean basin, extending from eastern Asia to the west coast of North America, and down to Australia. Though there are many things to be analyzed in this image, we want to focus in on the Sea of Japan, in the top left corner of this image. The Sea of Japan is located between mainland Asia and the island nation of Japan. On August 4th, SST anomalies read well above normal in this area. This was a concerning feature, as above normal water temperatures can induce persistent high pressure to form over the area, an ability well documented this past winter with positive SST anomalies in the northeast Pacific, and consequential high pressure in that same area, which enabled the polar vortex to grace the northern US.
The feature was primarily of concern for winter weather fans, as the persistent high pressure forming over Japan due to the warmer than normal Sea of Japan could continue into the fall and winter, which would then allow for increased risks of warmth in the United States during the coming winter season. The mechanism which may allow for this warm winter would be the highly-touted Typhoon Rule.

In just 10 days, however, the scenario for the coming winter changed drastically.

The image above shows sea surface temperature anomalies, still projected over the same part of the world, but now valid on August 14th, 2014. Gazing around the chart, we find a stunning reversal in water temperatures in the Sea of Japan. Instead of +3.00º to +4.00º-plus anomalies in the Sea of Japan, we now see widespread negative or neutral water temperature anomalies. This rapid cooling also appears to have affected the waters immediately south of the Sea of Japan.
It's quite possible, even likely, that the destruction of these warm water anomalies is due to a strong low pressure system traversing the Sea of Japan. It is quite common for strong cyclones to "mix" the water it passes over, reducing warm water temperature anomalies in the process. It looks like this same process has happened in the Sea of Japan.
If, and I say 'if' because things can very much change in the next several months, these cool water temperatures are to sustain themselves in the Sea of Japan, and warm waters do not return to the area, the chances of a warm winter would likely be reduced. However, we'll need time to monitor this development for another handful of weeks to see exactly what will end up happening.