Will he or won’t he? Weak El Niño’s impact on our Winter unclear

Posted at 8:34 AM, Oct 05, 2012
and last updated 2012-10-05 09:47:48-04

RICHMOND, Va. (WTVR) – We may remain on “El Niño Watch” according to the Climate Prediction Center (CPC), but with such puny signals from the Equatorial Pacific late Summer into the beginning of Fall, we can’t count on El Niño to be a dominant guide for a Winter outlook. The CPC issued this update, “Due to the recent slowdown in the development of El Nino, it is not clear whether a fully coupled El Niño will emerge. The majority of models indicate that borderline ENSO-neutral/ weak El Niño conditions will continue, and about half suggest that El Niño could develop, but remain weak.”

What is El Niño, and why does it matter anyway?
El Niño is the warming of the Equatorial Pacific surface and near-surface waters off of the northwest coast of South America. When you warm that much water, it will impact wind patterns globally. Here’s what a strong El Niño looks like on sea surface temperatures:

Climate Prediction Center: Sea Surface Temperatures (°C).

And this is what the warm departure looks like:

Climate Prediction Center: During a strong El Niño ocean temperatures can average 2°C – 3.5°C (4°F – 6°F) above normal between the date line and the west coast of South America.

Here are the typical El Niño weather impacts during the Northern Hemisphere Winter/Southern Hemisphere Summer because of El Niño-driven wind pattern changes:

Climate Prediction Center

There is substantial evidence that when El Niño occurs in the North American Winter, it brings cooler and wetter-than-average winters to the Southeast U.S., including into Southeast Virginia. Obviously, that is of significant interest to us in Virginia!

Here’s what the transition from La Niña to weak El Niño has looked like since Fall 2011 until now.

Climate Prediction Center

And here’s a closer look at the sea surface temperatures and anomalies now.

Climate Prediction Center

The anomalies are barely showing a warm departure in the eastern Equatorial Pacific. Hence, why the CPC has to call this a near-ENSO neutral/weak El Niño. There’s just not enough evidence to indicate that El Niño will continue or strengthen into the coming weeks and months. That means long-range forecasters trying to predict what kind of Winter we’ll have in different parts of the U.S. can’t rely on the usually helpful guide provided by an El Niño or La Niña Winter. In fact, even the climate computers are saying, “Eh, maybe, maybe not.”

The International Research Institute for Climate and Society

So what does that mean for me as a meteorologist trying to look ahead for you? I’ll have to focus more on patterns that set up over shorter time-frames, on the scale of days to a week or so, as opposed to months. In other words, I plan to approach my Winter forecast as if all bets are off and anything can happen. I can’t say we’ll have a dud of a Winter without storms and deep cold. Neither can I say we’ll have an epic “snowmageddon” repeat. It’s just unclear, based on this Call-Me-Maybe-El Niño. (Oh dear, now I have that song in my head…)

One long-range outlook has already been released based on the prevailing pattern this year (i.e., hot and dry in the central and southwest U.S.).  The current seasonal drought outlook shows persistence of the drought in the drought-stricken central and western U.S., with improvement in Virginia.

Our Abnormally Dry area in the Commonwealth is down to 43 percent of the state compared to three months ago when 91 percent of the state was at least Abnormally Dry. However, the Moderate Drought (D1) is worse now than three months ago in central and northeast Virginia, but did show a slight improvement over the past week.

Meteorologist Carrie Rose
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