El Niño on its way by summer, new data show
New data suggest an El Niño weather pattern -- one that could bring wetter, cooler conditions this summer -- is likely to unfold as the crop season advances. But, that same pattern could spell even more severe trouble for parched farms in the western U.S.
Sea surface temperatures (SSTs) in the tropical Pacific Ocean -- a key indicator when predicting which way El Niño-Southern Oscillation (ENSO) will swing -- have risen lately, some to their highest levels since September 2012, according to MDA Weather Services senior meteorologist Bob Haas. But beyond these SSTs, subsurface water temperatures have started to trend higher, firming the belief that El Nino could be firmly in place by summer.
"Looking below the surface, an impressive swath of warmth remains in place, with another slight shift upwards/eastward," Haas says. "This area of subsurface warmth continues to look most similar to 1997 around this time, which turned into the strongest El Niño on record."
While it's far too early to say that strong of an El Nino system will take over later this year, "ongoing trends toward some level of El Niño by the summer months continues to look more likely with each passing week," Haas adds.
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In the nearer term, though some forecasters say a dry, warmer weather window is likely to open later this week, the prognosis is for moisture to dominate through much of the eastern half of the country, including the Corn Belt, northern Plains and mid-South, according to David Simeral of the Western Regional Climate Center.
"The NWS HPC 7-Day Quantitative Precipitation Forecast (QPF) calls for moderate-to-heavy precipitation accumulations (two-to-six inches) across the lower Midwest and moderate accumulations (two-to-three) in the South and Southeast. The Upper Midwest, New England, central Rockies, and Pacific Northwest are forecasted to receive accumulations of less than two inches," he says. "The 6-10 day outlooks call for a high probability of above-normal temperatures across the West while below-normal temperatures are forecasted across the South, Midwest, and Eastern tier. A high probability of above-normal precipitation is forecasted across portions of the Southeast, Mid-Atlantic, New England, northern Plains, and Pacific Northwest while the remainder of the West, southern Plains, and western portions of the South are expected to have below-normal precipitation."
On the opposite side of the spectrum, the water worries remain heightened in the western half of the country, especially in California, where the drought's severity continues to sharpen. Simeral says parts of the northern Sierra region have received less than 1/3 of the normal snowfall, and that could translate to even drier downslope conditions. And, those conditions -- also typical of an El Niño pattern -- are stretching east as far as Colorado.
"Despite short-term gains, the long-term deficits across the region remained substantial. According to the California Department of Water Resources, California's snowpack has increased since the first snow survey on January 3rd, but the latest survey results show California's snow-water equivalent is only 32% of the average April 1st measurement when the snowpack is generally at its peak level prior to spring melt," Simeral says. "In the Southwest, a warm and dry pattern continued across the region leading to slight deterioration of conditions in southwestern Colorado."