It is now clear that a very strong or "super" El Niño will be in place this year.
Some are even calling it a GODZILLA El Niño.
Several media outlets and amateur YouTube channels/social media sites suggest the impacts will be like a regular El Niño on steroids: very warm, wet, with a low snowpack.
For example, Oregon Public Radio:
The Bellington Herald throws caution to the wind, predicting drought and floods! Plus fires. Devastating impacts for Whatcom County. Meteorological "end times".
For example, the Summit at Snoqualmie folks looked at the snow statistics associated with very strong El Niño years and found snow totals near normal (link here)
In summary, past events suggest that the Northwest impacts of a very strong El Niño are quite different from its moderate relatives.
And in my previous blog on very strong El Niños, I found the same thing: Northwest snowpack can be quite decent during "super" El Niño years.
So how can this be?
Why do moderate El Niños cause one impact and "super" El Niños result in something different?
Let's figure this out using real data.
The figure below shows precipitation associated with moderate, strong, and very strong ("super" or Godzilla) El Niño years for October through March.
The difference from normal is shown, with blue and purple indicating above-normal, and yellow and red indicating below-normal precipitation.
Moderate and strong El Niño years are drier than normal over the Northwest, but "super" years, like this year, are WETTER than normal.
No drought expected. Plenty of water for our region.
Surface air temperature?
Moderate and strong years are close to normal over the Northwest (below). For "super" years like this one, temperatures are very modestly warmer (about 0.5 C or about 1F; see the blowup below).
No wonder snowpacks remain decent for Super El Niño years: only slightly warmer but with much more precipitation.
The Snoqualmie Pass folks were on to something!
Finally, can we explain these differences in a more fundamental way?
To do so, below are upper-level weather charts (500 hPa heights; think of these as pressure around 18,000 ft)
All El Niño events are associated with an enhanced low-pressure system over the northeast Pacific (the purple colors). Air circulates counterclockwise around lows.
For the moderate El Niños, the low is centered well offshore. Strong events have the low much closer to the coast, which is not favorable for precipitation over our region. But for the "super" events, the low is more offshore, producing more moist southerly flow over our region.
Just right.
In summary, past events suggest that the Northwest impacts of a very strong El Niño are quite different from its moderate relatives.
Importantly, Northwest drought conditions are not expected with a very strong El Niño, and there is good reason to hope for a near-normal snowpack.
Media and social media predictions of some kind of meteorological "end of times" are without support.
if you ever go downtown Bellingham,
ReplyDeleteWhere the Harold building is at you'll know not to take that paper too serious. The editor was probably stoned
It looks like in Super El Nino years we are more influenced by the strong pacific jet that in moderate and strong El Nino years goes more into California. Speaking of which will also likely have a huge snowpack in the Sierras this year. No talk of drought in California, thats for sure. Next Spring should be a good time to check out the waterfalls of Yosemite. They will be raging.
ReplyDeleteIn the spring of 1998, after another historically strong El Niño, my then-fiancé and I drove down from SF, where we had just moved from the East Coast, to see Death Valley for the first time. The entire valley floor was covered in a carpet of tiny flowers that apparently could go for years without making an appearance, and many of the 4-wheel-drive only roads we wanted to try were washed out from the rains. If this year is anything like that one, Death Valley will be quite the sight to see in the spring!
ReplyDeleteNice summary. I have been living with El Nino/La Nina my entire life on the west coast, since 1950. Each one can be different and has been. Putting together a very strong El Nino with climate change ocean warming and I bet we see a mild wet winter. No one knows about snowfall except what history tells us and the past decade has shown that averages don't mean a lot. Last year was a La Nina winter. Super low precip and snowpack in Oregon. I am hoping for snow. Make it happen Scotty, or Cliffy.
ReplyDeleteWhat is the effect of a super El Nino on the frequency of atmospheric rivers and damaging rain/wind storms?
ReplyDeleteExcellent information, as usual, Cliff. Thanks very much. And I love the mouse towering over Godzilla, too.
ReplyDelete