EL NIÑO IS GONE … WHAT’S NEXT?
El Niño has come and gone, and at least for Texans, it was every bit as powerful as advertised. What’s next? During late spring and early summer, conditions transitioned from El Niño to what is described as a neutral weather pattern (neither El Niño nor La Niña). But weather forecasters expect that to change into La Niña conditions soon.
Before we focus on La Niña, let’s take a look back at El Niño. Since that weather pattern began drenching the state, the Brazos River basin and other parts of the state experienced record rainfall. The good news is that our reservoirs filled up. The bad news is that the area experienced widespread flooding, and in some areas of the lower Brazos basin, it was a level of flooding that shattered previous records.
A multi-year drought was eliminated thanks to El Niño-driven rainfall, but the flooding proved there really can be too much of a good thing.
So how strong are the chances that La Niña is coming? Texas State Climatologist John Nielsen-Gammon says “it’s almost certain” to develop later this year. The bad news is that the multi-year drought that plagued Texas started with a La Niña.
Fortunately, El Niño has given us plenty of water in our reservoirs. The six months from November 2015 through April 2016 was the seventh-wettest stretch of that length in Texas records, which date back to 1895, Nielsen-Gammon said, despite a dry two months to start the year. During that dry stretch, some people referred to El Niño as El Nada or El Busto, but that two-month stretch was merely a respite from the rain that drenched the state throughout the spring.
La Niña conditions in the Brazos basin and throughout Texas typically mean higher chances for drier weather overall. But La Niña conditions also usually mean a more active hurricane season, and forecasters are predicting what could be the busiest hurricane season in four years.
La Niña is the cool phase of the El Nino-Southern Oscillation (ENSO) climate pattern -- a naturally occurring phenomenon that involves fluctuating ocean temperatures in the Pacific. La Niña is the opposite of El Niño, which is the warm phase of the cycle. El Niño is characterized by warmer waters in the central and eastern Pacific Ocean. La Niña features a cooling of those same Pacific waters.
U.S. National Oceanic and Atmospheric Administration climate models indicate there is a 75 percent chance of a La Niña forming by the end of this year (www.climate.gov).
The NOAA website notes there have been 14 La Niña weather patterns since 1950 (and 23 El Niño patterns during that same timeframe). Of those 14 La Niñas, nine immediately followed El Niño years. Two occurred two years after an El Niño, with a neutral year intervening. Two were the second year of a “double dip” La Niña, where sea surface temperatures briefly returned to neutral during the summer before heading back into La Niña territory.
All La Niña events in the NOAA records have started within two years of an El Niño. (But not all El Niño events are followed by La Niña.) El Niño does not have a similar rule, as several of the 23 El Niños on record have started four or more years after the last La Niña.
La Niña tends to last longer than El Niño, often lingering for back-to-back years. While forecasters are still figuring out the potential impact of a La Niña pattern, the Weather Network notes that, “There does seem to be a correlation between significant patterns … after the pattern swings significantly in one direction - either a strong, sharp peak or a prolonged event - there tends to be a significant counteraction in the opposite direction.
With the (recent) El Niño having matched the overall strength of the strongest pattern in the record books (from 1997-1998), from just a glance at the similar El Niños from the past, it's easy to see how something significant should develop later this year in response.
John Nielsen-Gammon, Texas State Climatologist
Nielsen-Gammon explains it this way: “What that means is that it still seems likely that temperatures will cool enough to reach La Niña territory by late summer or fall. The Climate Prediction Center rates the chances of a La Niña at about 75 percent. By next winter, if La Niña is in place, Texas is likely to experience a warm and dry winter.”
Still, the La Niña pattern is variable.
Each year in a La Niña year is different,” said Nielsen-Gammon said. “Some differences are due to the particular year’s pattern of La Niña Pacific Ocean temperatures, some of it is due to what’s happening in the Atlantic Ocean, and some of it is just the randomness of the weather.
As we wait for the impact of La Niña, the outlook is hazy, but it should get much clearer in the coming months.