You may have already heard some buzz about a “super El Niño” developing over the next several months, with some possibly dire consequences in global weather patterns.
The reality of how “super” it gets remains to be seen, but the potential for the equatorial Pacific sea surface temperatures to warm to a level sustaining an El Niño episode by summer or fall extending into next winter appears to be quite strong. And that could result in some dramatically different weather than what we’ve been having the past few months.
What we have now is severe to extreme drought — though Monday brought somewhat more widespread and voluminous rain than expected, with many locations in Cardinal News’ Southwest and Southside Virginia coverage area getting ½ to 1 inch. More showers and perhaps a few thunderstorms are expected on Wednesday.
Monday’s rain was the kind of rain that would be really beneficial for the dryness if we could get two or three of those each week for the next three months, but rain usually isn’t that evenly distributed on such a timescale. There are already signs of a hotter, drier pattern returning by next week after a cool, occasionally showery start to May that followed a historically hot and very dry April.
The more likely avenue for eventually ending our drought is a couple of months of frequent heavy rain, and an El Niño-influenced atmospheric pattern over North America could be a conduit for such a sequence.
Shift from La Niña to El Niño
La Niña conditions, or the cooling of sea surface temperatures in the equatorial Pacific, have been present most of the time since mid-2020. The one significant exception was mid-2023 through spring 2024, when a moderate El Niño developed for a few months.
The almost continuous La Niña from mid-2024 to early this spring correlates strongly with a tilt to dryness that has now fully manifested in the development of severe to extreme drought across our region and much of the Southern and Eastern U.S.
This is very reminiscent of where we stood in 2001 and 2002 with an even more intense drought, following almost three full years of La Niña.
La Niña historically has edged toward long-fused drier patterns for our region, as the moisture-bearing subtropical branch of the jet stream is weak or non-existent and high pressure over the southeast U.S. often deflects wet storm systems to the west and north.
El Niño, by contrast, more often influences the development of a strong subtropical branch of the jet stream over the southern tier of the U.S. that can — often but not always — swing in multiple wet storm systems that affect our region.
El Niño episodes not all the same
When discussing the role of El Niño and La Niña in our regional weather, it is always important to remember that these phenomena do not act alone, but rather in combination with myriad other climatic oscillations, such as the North Atlantic and Arctic oscillations.
Variations in the strength of El Niño and La Niña, the location of the core of the more extreme sea surface temperatures, interactions with other climatic factors, and other sometimes subtle influences can create different weather outcomes for a given location when compared with similar historic episodes. There are discernible trends in observed weather with El Niño or La Niña but not certain outcomes for particular seasons or years.
Sometimes El Niño and La Niña get a little too much credit as the end-all and be-all of weather trends.
That said, they are important drivers for a series of patterns that often occur around the world. What is projected in months ahead is getting extra attention because many computer forecast models project it to be a “super El Niño” or at least a strong one, intensified by the overall state of warming global climate and hotter oceans.
One extreme El Niño that has been mentioned as a possible comparison occurred in 1877-78 and is blamed for drought and famine in Asia and South America that may have killed as many as 50 million people.
Very strong El Niños have occurred more recently in 1982-83, 1997-98, and 2015-16, years that brought notable periods of extremely wet and sometimes stormy weather across the southern tier of the U.S. into our region.
The parallels in our region between winters in 1982-83 and 2015-16 — unseasonably warm Christmas, big snowstorm a few weeks later — are almost eerie, and 1997-98 was the wettest winter on record at Roanoke and among the few wettest at several other locations in our region. The 2015-16 winter also included the deadly Feb. 24 tornado in Appomattox County, spinning out of exactly the kind of strong southern stream storm system common during an El Niño.
Winters more affected than summers
Winter is when the state of the equatorial Pacific gets the most attention, generally has the most influence, and often, carries the most misconceptions.
One idea that has often planted itself for many in the Eastern U.S. is that El Niño means it will be snowy and La Niña means it won’t be. The truth, of course, is more complicated than that. We will revisit that when it is more seasonally relevant. Short answer specific to our region: Expecting a wet winter with El Niño is reasonable, though not certain, but snow fortunes can be feast or famine.
El Niño and La Niña correlations to summer weather are weaker than those in colder months, but it can generally be said that summers with an El Niño or are transitioning to El Niño are typically not among our region’s hottest. There may be just enough influence on a more vigorous west-to-east flow to stymie the stagnant highs that need to park over us a while to really sizzle.
In the fall, it is often noted that El Niño patterns focus tropical activity in the Pacific Ocean while there tend to be fewer hurricanes in the Atlantic basin. Tropical systems feed off the ocean warmth in the Pacific, while the increase in upper-level winds over the Atlantic can rip the tops off developing tropical systems.
There is always a degree of speculation with equatorial Pacific sea surface temperature projections and even more so in the potential effects, but with warming oceans in that region since February and large consensus in computer projections, it appears very likely an El Niño will develop, possibly as early as mid-summer.
Be that “super” or even something more moderate, we probably won’t be talking about drought a year from now, and could even be begging for some dry weeks.
Journalist Kevin Myatt has been writing about weather for 20 years. His weekly column, appearing on Wednesdays, is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley.
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