Ocean conditions on the cusp of El Nino
El Nino isn't quite officially here yet, but it's close.
That's the latest from NOAA's Climate Prediction Center, which put out its September version of its monthly update Thursday.
El Nino is part of the 3-7 year cycle when temperatures in the equatorial Pacific Ocean warm (El Nino) then cool (La Nina) with "neutral" conditions in between. We've been just below official El Nino conditions much of the summer after spending the past two winters dealing with the opposite La Nina. I was expecting the September outlook to declare an "El Nino Advisory," meaning it's here, but they have continued with the "El Nino Watch" which means... perhaps soon. (Their next discussion will come out in early October.)
Their discussion states that while ocean temperatures have been warming, the atmosphere hasn't responded yet and thus the delay in getting true El Nino conditions, but that it's inevitable El Nino will arrive sometime soon and last through the end of the year.
Some climate models indicate this El Nino will be borderline moderate in strength, while others suggest it'll be a weak event.
Are we set for most boring winter ever?
El Ninos in Western Washington are synonymous with generally warmer and drier winters as historically, that's how they roll. But that doesn't mean every El Nino winter will be boring.
There have been four prior El Nino events since 2000, and some have not followed the script.
On the dry/warm side was 2002-2003, which didn't get any snow at Snoqualmie Pass until December and had periods early in 2003 with zero snow at the pass. In the lowlands, Seattle was pretty normal for rainfall until January which was quite wet, then February which was quite dry. March was very wet again. However temperatures from November to January were much warmer than normal.
The next El Nino was 2004-2005 which had the least amount of annual snow at Snoqualmie Pass (216" fallen, average 435") since 1991-92 (211"). In the lowlands, Seattle was about spot-on normal for temps October through December but warmed considerably as we got into late winter. Rainfall was below average through the fall and winter.
The winter of 2006-07 was also El Nino, but that November was the wettest month in Seattle history, followed by the big Hanukah Eve wind storm in mid December and then a big cold snap in January. (And not to mention a foot of snow fell in the North Sound on March 1). Above average rains continued through December and January before trending closer to normal. Overall, temperatures in Seattle were pretty close to normal through the fall and winter.
The most recent was 2009-2010 which was pretty wet in October and November, but then dry and cold in December. But lowland snow was missing in Seattle -- just the 10th time we went through a winter without measurable snowfall -- even less than Houston! (They got 1"). November, January, February and March were all considerably warmer than normal.
So three out of the past four have at least had some hall mark of El Nino, but certainly not as if it'll be 90 days of continued sunshine this winter.