Changing Water Temperatures in the Pacific
This time of year is critical in regards to sea surface temperatures in the Pacific Ocean as pockets of warmer and colder water can have a big impact on the coming winter and spring season.
This past winter and spring (2017-2018) was dominated by a moderate La Nina in the Pacific (colder waters). The winter and spring of 2017-2018 followed closely the expected trends you would expect during a La Nina (dry west, colder in the north and east).
Over the course of the summer season the sea surface temperatures in subtropical Pacific have climbed and a weak El Nino may be forming. If not an El Nino, an El Nino Modoki (weaker El Nino) will form.
Another critical area that is worth watching to get a hint about the winter season is the north Pacific, especially in the region of the Gulf of Alaska. When the sea surface temperatures are warmer in the Gulf of Alaska it is a signal that the lower 48 states may experience colder temperatures in the winter season as high pressure like to build over the warmer waters directing the jet stream to the southeast and opening the door to Canadian cold.
The graphic below shows global sea surface temperatures as of this past weekend.
Of interest is the area between South American and Australia, where there is a mix of blue (colder) and orange (warmer) sea surface temperatures. This indicates a weak El Nino or a Modoki El Nino. Also, notice the bright orange area (warm) developing in the Gulf of Alaska. As stated above, the warmer sea surface temperatures developing there is a cold signal for most of the USA this winter.
A weak El Nino near the equator and a warm Gulf of Alaska could me some cold weather is on the way this winter from the east slopes of the Rockies and into the Midwest and East.