It is still true that La Niña tends to correlate with dry water years, which the National Weather Service defines as from Oct. 1 to Sept. 30. During La Niña, the sea surface temperatures of the central and eastern Pacific Ocean cool. And the jet stream - the west-to-east band of wind in the atmosphere - shifts northward. This typically pushes winter storms toward the Pacific Northwest and Canada, while leaving swaths of California drier than average, especially in the south.
General Pattern: La Niña conditions are expected to persist through winter, favoring a split temperature pattern across the US. Colder Areas: Below-normal temperatures are favored from the Upper Mississippi Valley, Northern and Central Great Plains west to the Northern Rockies and parts of the Pacific Northwest. Early December is likely to be colder-than-normal in the Midwest and northern states due to atmospheric patterns including a negative Arctic Oscillation and a modulating Madden-Julian Oscillation.
Storm causes havoc as it hits centre of the country, displacing hundreds of thousands. Residents have sought refuge on rooftops, and cars have floated through flooded streets as Typhoon Kalmaegi has battered the central Philippines, killing at least two people. Hundreds of thousands have been displaced by the powerful storm, which made landfall shortly before midnight on Monday. The 20th tropical cyclone to batter the Philippines this year was moving westwards at 25km/h (16mph) on Tuesday
After months of slight temperature shifts in the Pacific Ocean, La Niña has officially returned - the climate pattern that typically drives drought in Southern California. The National Oceanic and Atmospheric Administration announced Thursday that La Niña conditions had arrived, a possibly foreboding sign for the Southland. The southern half of the Golden State still has not bounced back from the last year of below-average rainfall, and the reemergence of the ocean phenomenon could mean more drought, with another drier-than-average winter.
