Forecast models are now calling for this El Niño to be the strongest on record
Original article posted on www.washingtonpost.com by Angela Fritz dated August 21, 2015
As of this week, the average of the group of forecast models used to predict the intensity of El Niño are calling for an event that would surpass the record-strong El Niño of 1997-1998.
El Nino, which is a measure of how abnormally warm the tropical Pacific Ocean is, can be classified as “very strong” if surface waters are running at least 2 degrees Celsius warmer than average for at least three months in a row. While this can be a difficult metric to achieve — it’s only happened twice before — it’s looking more like this year will not only jump that hurdle, but also surpass the old record.
Colorado State meteorologist Phil Klotzbach plotted the 1997-1998 El Niño on top of the most recent forecast, showing how the model average — in yellow below — is warmer than the previous record El Niño all the way through spring of next year. It’s close, and only slightly stronger — but it’s a big change compared to forecasts from recent months.
Dozens of global forecast models are used to help predict the future intensity of El Niño. Some are “dynamic,” meaning they take actual current global conditions and physically attempt to define what will occur in the future. Others are “statistical,” which means they predict the future based on what happened during a similar situations in the past.
Once a month, these models are compiled by NOAA and the International Research Institute for Climate and Society. And month after month, they have continued to predict a stronger and stronger El Niño.
[July was the hottest month on record for Earth, in its hottest year so far]
Jan Null, California weather expert and owner of Golden Gate Weather Services, has been tracking the monthly forecasts since May. Each month, the peak El Niño intensity from the dynamical models has increased. With the caveat that there are no guarantees, Null says the forecast trend “is very encouraging for a continuing increase in the chances of above normal precipitation in California” this winter.
In the West, a very strong El Niño would greatly increase the chances for torrential rain storms this winter — something that drought-stricken California direly needs.
On the East Coast, an epic El Niño could mean a very wet winter, but not necessarily a snowy one. Interestingly, El Niño increases the moisture supply in the eastern U.S., but it also tends to keep the polar jet — and all of its cold air — farther north. “The combination of these two El Niño effects sometimes means D.C. gets flooded with mild air throughout the winter, favoring rain rather than snow when moisture-laden storms come along,” wrote Jason Samenow. “But, at other times, just enough cold air hangs around for it to get hammered by a crippling snowstorm.
In other words, with all of the moisture El Niño can supply, the East Coast might only need one good shot of the Polar Vortex to push snow totals above average.
Given all the ways a very strong El Nino can impact global weather, meteorologists have been watching this year’s with bated breath. “This is a really big deal,” said Tony Barnston, chief forecaster for the International Research Institute, in a video on the new forecast. “We’ve already seen impacts from this El Niño — India had a weak monsoon, we’ve been dry in the Caribbean and in a lot of Central America and in Indonesia.”
But although the models keep pushing this El Niño stronger, Barnston is still cautious about making a record-intensity forecast, simply because the 1997-1998 El Niño was so incredibly strong. “It could be a record, but probably its more likely it will be just below the 1997-1998 event, maybe a little bit weaker,” said Barston. “But that [event] was so strong, it’s hard to equal that again.”