Today, NOAA's Climate Prediction Center (CPC) announced its cancellation of the La Nina Watch that was in place. Thus, they expect that we will experience Neutral or La Nada conditions during the upcoming winter.
Now this announcement is not as significant as it might seem, since the forecast La Nina was predicted to be very weak. As most of you will remember La Nina is associated with cooler than normal water in the central tropical Pacific (the Nino 3.4 area is generally used). Specifically, weak La Ninas are associated with a cool temperature anomaly (difference from water) of at least .5C. Neutral conditions occur when the Nino 3.4 temperatures are within .5C of normal.
Here is the latest forecast for a collection of global models (the NMME ensemble) for sea surface temperature anomalies in that Nino3.4 area. Temperatures cooled rapidly in Spring and early Summer as last year's El Nino faded. The forecasts of these models are virtually on the same page--slightly cooler than normal in the neutral temperature range.
So it is probable that we will experience a Neutral-type winter, which has implications for the upcoming weather here in the NW. Remember there is no certainty here, but rather the atmospheric "dice" are weighted toward the following weather conditions in the Northwest during La Nada years:
1. Near normal precipitation and temperature.
2. Greater chance of extreme weather such as heavy precipitation, windstorms, big snowstorms.
Remember these big events are still rare, but they do have a tendency to occur in Neutral years.
We also might expect normal reservoir conditions going into next summer.
Announcement: Talk on Northwest Climate Surprises on September 28.
During the evening of September 28, I will be giving a talk in Seattle at UW's Kane Hall on Climate Surprise: Unexpected Impacts of Global Warming on the Pacific Northwest. You think global warming will simply bring warmer temperatures, drought, less snow, and more storms? Think again. The latest climate model simulations provide a far more nuanced prediction of what will happen here, with some of the results quite surprising. This talk is sponsored by CarbonWa and the Audubon Society To find out more or to secure tickets, please go here.