ENSO update, winter outlook defined a little more, outlook unchanged

• ENSO status and forecast
• What does this mean for us and our winter?
• A little about the PDO (Pacific Decadal Oscillation) and what it has at play as well.

Today the NOAA Climate Prediction Center released their monthly ENSO status and forecast discussion.  The current ENSO status is now set to "Not Active".  This means conditions and forecast models now point to an ENSO neutral winter, so no watches or advisories are issued.  As I discussed in my previous ENSO outlook (Fall and Winter Long Range Outlook and ENSO status), conditions were favoring a neutral winter.  I suspected as such due to a cold phase PDO (Pacific Decadal Oscillation) primarily, among other global oscillation phases currently going on right now.

What does this means for us for our remaining fall and winter season?

Generally with the neutral ENSO fall/winter/spring or our wet season, we average near normal for temperature and near normal for precipitation. However some of the most historic storms in this region occurred during a neutral winter season. The recently talked about Columbus Day storm of 1962 occurred during ENSO neutral fall. Our Winter storm cold snap of December 2008 shutting down the region for nearly 3 weeks was also during a neutral ENSO winter season. The chances of a repeat of winter of 2008-2009 are very strong. At least one snow event is likely, more likely that we will have several snow events and a few other strong storm systems as well. Make sure you are prepared for winter storms now, before it's too late to get supplies in the rush of storm warnings.  We may also see severe temperature swings, we could have a 2 week stretch of highs in the 60's, but then another one week stretch of sub-freezing temperatures, possibly lows in the teens at times.

The Pacific Decadal Oscillation (also known as the PDO) usually switches phases once every 20-30 years. From about 1976 until about 2006 we were in what was called a warm phase. Really things started showing signs of switching right around the year 2000, and starting in 2008 we have been in a full blown cold phase mode. However the El Niño's and La Niña's have masked the typical activity of a cold phase PDO. 2008-2009 winter season was our last and only neutral winter occurring during a cold phase PDO in any recent history, particularly in Satellite history. Many of the most severe winter storms to strike our region occurred during an ENSO neutral winter season, with a cold phase PDO in effect. These were the conditions that we had in the Fall of 1962, and during many other major storms that have affected this region. Some of you may remember the sudden heavy convergence zone snow storm that struck December 18, 1990 stranding people at work and kids at school throughout everywhere between Sea-Tac and Lynnwood. Interestingly enough the PDO had for about 2 years during that time dipped into a slight cold phase before cranking back to its normal warm phase, and 1990-1991 happened to be an ENSO neutral winter season as well.

It is difficult to read clearly, but below is a line graph of the past 25 years starting January 1987 - August 2012 of the ENSO (blue line) index compared to the PDO (red line) index.  You can see where the little dip was in 1990, and also see how neutral years are uncommon.  A neutral year is defined when an index number is less than +/- 0.5.

Negative Numbers indicate Cold Phase or La Niña, Positive Numbers indicate warm phase PDO or El Niño.

So, these are some things to keep in mind while preparing for the 2012-2013 winter season, which has already started. We all hope we do not have any severe weather, except maybe the kids that want snow, however, weather patterns and global oscillations are favorable for a stormy and eventful winter this season.

My judgment on our local weather is based on my personal studies of historic weather coordinated with the known past of global oscillations and global events, including but not limited to the ENSO (El Niño Southern Oscillation.) Links to many of my resources can be found at Carl's Shoreline Weather Station, under weather links.

Twitter: @SWeatherWatcher