A Faltering El Nino

The difference between a strong El Nino winter and a neutral winter (neither El Nino nor La Nina) can be a large one.

Strong El Nino winters are generally warmer and drier than normal. Less big storms.  Considerably less snowpack in the Cascades and little, if any, snow in the lowlands.

Neutral winters bring "normal" weather and have a bit of a twist:  the biggest storms--the greatest floods, windstorms, snowstorms--when they happen (which is rare), tend to occur in neutral years.  Years that Seattle mayors need to worry about, as should the keepers of the 520 bridge.  Buckle your meteorological seatbelts--its looks like a neutral winter is coming our way.

As many of you know, the signs late last summer were for an El Nino, albeit a modest one.  But after a period of intensification, this El Nino has run out of steam and the current model forecasts (which are more accurate now because we are so close in time) suggest a neutral year.

Here is the latest record of the sea surface temperature anomaly (the difference from normal) for a region in the tropical Pacific (the Nino 3.4 area shown in the map below).   The official definition of a neutral year is when the anomaly is within .5C of normal.   Currently is it about .3C warm.  And the real El Nino effects aren't significant until the anomalies are much larger (at least 1C warmer or cooler than normal).   You notice that the warm anomaly increased significantly in June-early September and then plummeted.

Unusual sea surface temperatures cause changes in the atmospheric circulation and particularly the trade winds (the easterly tropical trades weaken during El Nino years).  Right now they are near normal.  What about the warmth of the upper portion of the oceans?   As shown here, it has dropped recently.

So what about our fancy computer models?   Well, the National Weather Service key tool is its coupled ocean atmosphere global model (CFS 2) ensemble.   Here is the output.  Predicting neutral conditions and no El Nino (temperature anomalies of the Pacific ocean 3.4 area are small).

And there are a variety of U.S. and international models that indicate either a weak El Nino or neutral conditions:

Folks...the cards are stack AGAINST our friend El Nino, with wily gamblers going for that wild kid, El Neutral (or La Nada).

So I told you earlier that although it is no sure thing, the biggest of the biggest storms of all kinds like neutral years.  Here is an example for windstorms (this is from a figure in my Northwest Weather book.  The red squares indicate a major windstorm year (like the 1962 Columbus Day Storm or the 1993 Inauguration Day Storm).  All of them are associated with temperature anomalies in the tropical Pacific between plus or minus one.  This year will be in that range!

I could show you a similar figure for floods or snowstorms, but that would only scare you.  And bring chills to the spine of Seattle mayors past and present.  Importantly, it is ok to get that season lift ticket pass for Stevens, Snoqualmie, or Crystal.

We might well escape a big storm, but in light of the above information it would pay to be ready.  Flashlights, extra supplies, etc.  I would have recommended getting a Subaru Outback (and was thinking of getting one myself), but they have run a series of insulting advertisements about weathermen. 

P.S.  I would like to thank those that contributed to my fund recently (upper right column or here).  I used the funds to pay for the room charges of the recent Columbus Day Storm gathering in Kane Hall and purchase a replacement disk server for our real-time weather predictions.  I also hope to give another undergraduate scholarship this year.