For about the last two years we have seen almost continuous La Niña conditions where ocean temperatures in the eastern equatorial Pacific are 0.5º or more below the long-term average. Despite this we have continued to see very warm global temperatures. An index that tracks the occurrence of La Niñas is the Southern Oscillation Index (SOI). The SOI is calculated based upon pressure differences between Tahiti and Darwin , Australia. Positive anomalies, seen in blue on the chart below correlate we...

On Thursday, September 10, 2020, NOAA issued a La Niña advisory.  La Niña conditions are here and there is a 75% chance they will persist through the winter. So what exactly is La Niña and what does it mean for the United States in general and for the Pacific Northwest? La Niña is a cooling of the equatorial Pacific and is based on water temperatures between 5°North latitude and 5°South latitude. A La Niña is characterized as weak (temperature 0.5°C to 0.9°C below normal) moderate (...

Thursday and Friday mornings (January 9 and 10, 2020) saw some light snow throughout the Puget Sound region, but with little or no accumulation. A slight warm up followed on Friday afternoon and continued into Saturday. On Sunday, however, big changes are on the way.  Outflow from the Fraser River Valley in British Columbia should start making its way into the Puget Sound by late Sunday afternoon. Plummeting temperatures are then expected through the middle of next week with lows in the te...

Climate Change and Climate Cycles We have heard a lot about global warming in the past few years. Then, in mid-November 2019, we saw cold temperature records shattered in much of the Central and Southern United States.  Concurrently, parts of Asia and much of Eastern Europe were experiencing abnormally high temperatures.  How can we put this all in perspective with respect to global climate change? Here is a little background. Late in the year 406 A.D. over a frozen Rhine River,...

We know that many events affect the climate on Earth.  We usually hear a lot about  El Nino and La Nina and their worldwide effects in the press and news.  Other phenomena such as the North Atlantic Oscillation and the Arctic Oscillation are discussed much less in the popular press but both these air-sea interactions can have major effects in both North America and Europe. One type of weather event, we rarely hear about is Sudden Stratospheric Warming (SSW). One might ask how can an event in the...

Seattle, where snow is relatively rare had its first White Christmas since 2008. Snow began in the area a little after 3PM on Christmas Eve, then continued on and off through about 11 AM on Christmas Day. Officially, SeaTac Airport reported 2.6 inches of snow and the National Weather Service office at Sand Point in Seattle reported 3.3 inches. Some other locations had a bit more - just about 5 inches in Sammamish, WA