El Nino changes weather worldwide, mostly affecting the United States in winter. The weather pattern happens every few years when the Pacific Ocean warms up around the equator. This year's is one of the strongest El Ninos on record.
NOAA expects a cooler and wetter winter for the South. For California, more precipitation than usual is expected during the critical time that its reservoirs usually fill, but there's no guarantee. Only northern tier states, the Ohio Valley states and Alaska should be dry.
Effects of El Nino:
El Nino's effects
NOAA: Thanks to El Nino, the US looks pretty wet this winter
NOAA has released an update to its El Niño advisory. This image shows the satellite sea surface temperature departure for the month of October 2015, where orange-red colors are above normal temperatures and are indicative of El Niño. This event is forecast to continue through the winter, likely ranking as one of the top 3 strongest events since 1950, before fading in late spring or early summer. El Niño has already produced significant global impacts, and is expected to affect temperature and precipitation patterns across the United States during the upcoming months. Seasonal outlooks generally favor below-average temperatures and above-median precipitation across the southern tier of the United States, and above-average temperatures and below-median precipitation over the northern tier of the United States. (Photo via NOAA)
MAKASSAR, SOUTH SULAWESI, INDONESIA - SEPTEMBER 21: Two girls are seen walk behind of dried up ricefield at Manggara Bombang village, Maros district on September 21, 2015 in Makassar, Indonesia. Indonesia's national disaster management agency has declared that the majority of the country's 34 provinces are experiencing drought caused by the El Nino weather phenomenon, the worst drought in the past five years. The dry season forces villagers to walk long distances to find clean water. (Photo by Agung Parameswara/Getty Images)
NOAA issued an update to the El Niño analysis on September 10, 2015, in which forecasters from the Climate Predication Center say a strong El Niño is in place and likely to peak in late fall/early winter, and gradually weaken through spring 2016. This image shows the satellite-based average sea surface temperature data from the week of August 31 - September 6, 2015. Blue areas are cooler than the 1981-2010 average; red areas are warmer than that historical base period. The large pool of warmer than average temperatures along the equatorial Pacific is indicative of the El Niño conditions. (Photo via NOAA)
Sea surface temperature anomalies in November 1997 (left) compared to July 2015 (right). (Photo via NOAA)
A couple tries to cool off from the heat caused by El Nino with water overflowing from a defunct but still watery reservoir called the Wawa dam in Montalban in Rizal, east of Manila on February 21, 2010. El NiÃ±o was expected to dehydrate the Metro Manila area over in the next two months, according to the Philippine Atmospheric Geophysical Astronomical Services Administration (Pagasa). Earlier this month the government warned a possible drought caused by the El Nino weather system could slash Philippines rice yields this year. AFP PHOTO / NOEL CELIS (Photo credit should read NOEL CELIS/AFP/Getty Images)
Tons of dead fish are seen on the banks of the Solimoes River due the water's low level, November 25, 2009 near Manaquiri, 120Km from Manaus. The dry season, affected by the weather phenomenon EL Nino, is worse this year. According a study from Brazil's universities USP,UNICAMP,UFRJ and Embrapa, the country could lose some USD 3.6 billion over the next 40 years. AFP PHOTO / ANTONIO SCORZA (Photo credit should read ANTONIO SCORZA/AFP/Getty Images)
Heavy clouds covers Indonesia's capital city of Jakarta on November 29, 2009. The month of November ends the dry season and starts the wet period but the weather bureau anticipates El Nino's dry spell to affect Indonesian weather. AFP PHOTO / Bay ISMOYO (Photo credit should read BAY ISMOYO/AFP/Getty Images)
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While California's drought is likely to lessen in January, even the wettest winter on record -- 33 years ago -- didn't have enough rain to wash out the current four-year drought, said NOAA hydrologist Alan Haynes of the California Nevada River Forecast Center.
Forecasters see a milder, warmer winter north of the Mason-Dixon line and for all of California and Nevada. Texas and the Deep South are forecast to be cold.
Overall, the nation should have 2 percent fewer days when people have to fire up their furnaces, said Halpert. He said the Northeast, where it was chilly and snowy last year, should see 6 percent fewer heating days.
Because of El Nino, NOAA is more confident than usual that its forecast is on target -- 70 percent for a wet South, Halpert said.
The federal winter forecast doesn't address snow, just wet or dry and warm or cold. Even though it's likely to be both cooler and wetter in the South, it is usually so warm there that it needs a blast of Arctic air for snowstorms and that's not looking likely, Halpert said. And while the north is likely to be warmer, past El Ninos have had some big snowstorms.
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This year's is one of the strongest El Ninos on record.
Historically, because there's more storminess during El Ninos, there's been a slight but not great increase in snowfall in the Northeast during El Ninos, said NOAA El Nino expert Michelle L'Heureux. But that could be skewed by a few big years in the past like the winter of 2009-10, she said. The Great Lakes area tends to get less snow during El Ninos, she said.
Private forecast firm Weather Bell Analytics predicts a swath from New Mexico across to the Carolinas and up the coast to Connecticut will get 50 percent more snow than usual.
AccuWeather, another private firm, sees severe thunderstorms in Florida, but forecasts less lake-effect snow around the Great Lakes, occasional mild days for the Midwest and says it will be "not as brutal" for the Northeast.