Wettest Month in State History – December 1933
In three previous newsletters we’ve reviewed the warmest (July 1985), coldest (January 1950), and driest (July 1960) months over the last 100 years for WA State. Here we complete the series with a look back at the wettest month in WA State history dating back to when modern records began in the 1890s: December 1933.
Read morePrediction of Mean Summer Temperatures in Washington State
Recent work at OWSC has led us to ponder just how predictable summer mean temperatures are in Washington state. We constructed a simple model for a workshop on El Nino-Southern Oscillation (ENSO) and the seasonal weather of the western US with this question in mind.
Read moreWinter Preview: What can we expect?
Now that our nights are getting longer and that familiar fall chill is in the air, folks are beginning to wonder what to expect for the upcoming 2016-17 winter. The El Niño of winter 2015-16 has been long gone, and neutral ENSO (El Niño-Southern Oscillation) conditions took its place this past summer.
Read moreThe Pacific Decadal Oscillation: How much longer will it remain in the positive state?
There is a close association between the short-term climate variability of the Pacific Northwest and the Pacific Decadal Oscillation (PDO). The PDO is fundamentally a mode or pattern of North Pacific sea surface temperature variability; Figure 1 shows the monthly PDO index since about 1970.
Read moreEarly Winter Weather for WA during El Niño
We return to the topic of El Niño and what it means for WA. Perhaps this constitutes an obsession, for which we make no excuses. The extremely wet month of December 2015 serves as motivation.
Read moreSea Level in WA during El Niño Winters
As readers of this newsletter are aware, the tropical Pacific is currently in an El Niño state. Such conditions in the tropical Pacific have usually, but not always, been accompanied by relatively warm winters in the mean for the Pacific Northwest.
Read moreWinter Preview: What Can We Expect?
As many of our readers are likely well aware, there is a high likelihood (between 60 and 65% chance) of a weak El Niño developing during the fall and winter. Sea-surface temperature anomalies are above normal throughout the equatorial Pacific Ocean at the time of this writing (more information in the Climate Outlook below), but the predicted El Niño has been slow to start.
Read moreSkill in ENSO Model Prediction
We have previously discussed the skill of seasonal weather predictions for winter in this newsletter (March 2014 edition). One of the most important sources of information for these seasonal forecasts is the future state of El Niño-Southern Oscillation (ENSO).
Read moreThe Arctic Oscillation and Pacific Northwest Weather
The Arctic Oscillation (AO), also known as the Northern Annular Mode (NAM), is an important element of the variability in the weather and climate of the Northern Hemisphere. It relates fundamentally to the state of the flow at northern latitudes, with the positive phase associated with a strong, axisymmetric polar vortex and the negative phase associated with a weak polar vortex, allowing for more prominent large-scale ridges and troughs for the whole hemisphere.
Read moreOn the Flavors of El Niño
It may seem that the climate community is often making a fuss about the phenomenon of El Niño-Southern Oscillation (ENSO), and this impression is correct. Why is there such an emphasis?
Read more