NOAA’s winter outlook is in line with classic La Niña expectations, but skewed toward a warm outcome, in keeping with the ongoing warmth of the 21st century. through Feb.), as predicted by NOAA on October 19, 2017. The outlook for temperatures (left) and precipitation (right) across the contiguous U.S. Image credit: NOAA/NWS Climate Prediction Center.įigure 2. Subsurface temperature anomalies (departures from average, in degrees C) beneath the equatorial Pacific, averaged across the 10-day period centered on Oct. With trade winds beginning to strengthen in the last few days, and a large pool of cooler-than-average water lurking below the surface of the tropical Pacific (see Figure 1), La Niña does appear to be a good bet for this winter.įigure 1. Most of the global models analyzed by the Australian Bureau of Meteorology on October 16 indicated La Niña conditions would develop. In its last monthly outlook, issued October 12, NOAA gave 55-65% odds that La Niña will be in place this fall and winter. A brief, weak La Niña extended through autumn and early winter 2016, and SSTs are once again near the La Niña threshold (0.5☌ below average in the Niño3.4 region of the equatorial Pacific). La Niña events often occur in pairs: the last set was in 2010-12. winters is to accentuate temperature contrasts between a chilly Northwest and a mild South, with an active polar jet stream leading to frequent storms and fronts. La Niña tends to favor an upper-level ridge over the northeast Pacific and a downstream trough over western North America. La Niña is the counterpart to El Niño, associated with cooler-than-average sea surface temperatures (SSTs) over the eastern equatorial Pacific. Signals are more mixed across the Midwest and Northeast, where periods of distinct mildness may be interspersed with sharp cold blasts. The best bets are for mostly milder-than-average conditions from California to Florida and a chillier-than-average winter over the Pacific Northwest. will likely be colored by La Niña, according to outlooks from NOAA and The Weather Company. Image credit: Scott Olson/Getty Images.įor the second year in a row, the upcoming winter across the contiguous U.S. For the first time on record, the city went through both January and February with no snow cover at all. Above: Winter finally looked like winter in Chicago on March 13, 2017, as people walk along the snow-covered lakefront near downtown.
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