Findings could help improve long-range winter forecasts
By Summit Voice
FRISCO — A new study that sorts El Niño events into two categories could help forecasters develop better long-range forecasts to predict how the periodic warming of equatorial East Pacific waters may affect winter weather.
Part of the data for the research came from an array of buoys across the Pacific called the TAO-Triton array. The buoys observes conditions in the upper ocean to forecast El Niño months in advance, and for monitoring it as it grows and decays.
After analyzing all El Niño events since 1979, the NOAA and University of Washington scientists said the El Niños that show a drop in outgoing long-wave radiation from the tops of deep convective clouds are the ones that tend to play havoc with winter weathers.
El Niños without that signal did not produce statistically significant anomalies in weather patterns. The dip in heat from deep convective clouds usually occurred before winter, so the timing of the signal could help forecasters improve winter seasonal outlooks, the scientists said.
The study was published in the February issue of the Journal of Climate, co-authored by Ed Harrison, Ph.D. of the NOAA Pacific Marine Environmental Laboratory in Seattle and Andrew Chiodi, Ph.D., of the NOAA Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington.
“When it comes to El Niño’s weather impacts, we are always looking for ways to improve our forecasting skill,” said Harrison. “Our goal is to extract the most useful information to predict El Niño seasonal weather anomalies.”
“By sorting El Niño events into two categories, one with OLR changes and one without, forecasters may be able to produce winter seasonal outlooks with more confidence than previously thought possible,” Harrison said.
El Niño refers to a warming of waters along the equator in the Eastern Pacific Ocean. Through its influence on the atmosphere, El Niño shifts tropical rainfall patterns which causes further shifts in weather around the globe, including milder winters in western Canada and parts of the northern United States and wetter winters in the some southern states.
Industry sectors from energy and construction to transportation and tourism are keenly interested in how El Niño will affect their costs. El Niño-influenced weather can affect fuel oil demand, travel delays, and retail sales. Better accuracy in El Niño predictions could help industry to prepare for its impacts more efficiently.