ENSO Blog

La Niña conditions prevailed through March, but it’s very likely the great La Niña of 2017–18 is a sinking ship. ENSO-neutral conditions are expected to arrive within the next couple of months, meaning sea surface temperatures in the central Pacific will return to near the long-term average. Amity Island The Niño3.4 Index, our very favorite measurement of the central Pacific sea surface temperature, was about 0.5°C cooler than average over the past week, according to the weekly OISST data set. This anomaly (the departure from the long-term average) is just on the border of neutral conditions: when the Niño3.4 Index is in between -0.5°C and 0.5°C. Of course, when we’re talking EN…   Read article

I know it may seem a bit ridiculous to say that winter is over when the eastern half of the United States keeps getting repeatedly smacked by nor’easters. But from a meteorological perspective, winter lasts from December 1 – February 28. And it is over. Which can mean only one thing! It is time for the ENSO Blog’s annual post looking back at how NOAA’s Climate Prediction Center’s Winter Outlook did. So for residents of the Northeast, I ask you to postpone shoveling out your car for 10 minutes, because it’s time to talk forecast verification. (I have an obsession, see here, here, here and here). Let’s start with the temperatures The Winter Outlook, which came out in November…   Read article

The great La Niña of 2017–18 is dwindling, and forecasters expect the return of neutral conditions by the March–May season, estimated at about 55% likelihood. Neutral conditions are favored to continue through the summer. It’s too early to get a picture of next fall and winter, due to the spring predictability barrier and the absence of strong signs one way or the other. There are a few interesting features we’ll watch closely over the next few months… but first, this update on current conditions! Stick your toe in La Niña may be weakening, but she’s still making an impression on the average sea surface temperature in the equatorial Pacific. The Niño3.4 index, which measures the depart…   Read article

Howdy readers! It’s now mid-February and while some of us are still dealing with the last vestiges of deep winter (wrapped up in wool blankets, sipping our hot tea, in the glare of our light therapy lamps), I thought it would be a nice time to recap what we’ve seen weather- and climate-wise so far this winter. Official winter for us meteorologists is the months of December-February, and although we’re not quite done, I still want to point out the changes in surface temperature over the U.S. so far because they’ve been really fascinating, likely in part due to the Madden-Julian Oscillation or “MJO.”  Wheel o’ MJO The What?  The MJO? This can’t be good! But please hang tight—he…   Read article

Many thanks to Tom for covering my post last month, allowing me to focus on the American Meteorological Society’s annual meeting (where I talked about the blog, and enjoyed my company on the plane ride home). It’s good to be back, and I’m glad to see our La Niña is still hanging around… although probably not for much longer. In fact, the current ENSO forecast from the Climate Prediction Center and IRI predicts a 55% chance that neutral conditions will be in place by spring 2018. Let’s get to it! Sea shanties During January, the sea surface temperature in the Niño3.4 region of the tropical Pacific—our primary measurement for ENSO’s ocean component—was close to 1.0°C cooler than the long…   Read article