El Nino: How will it affect our weather?

With all of the recent talk about El Nino and the effect it could have on the coming winter, NewsChannel 21 Chief Meteorologist Bob Shaw and Meteorologist Russell Bird offer up a closer look at the fascinating anomaly, and an early look at how it might affect the High Desert this winter.

El Nino, or “little boy,” got its name from its noticeable effect on climate around the Christmas holiday.

The ENSO, or El Nino Southern Oscillation, as it is known, is caused by warm ocean temperatures shifting from their usual position in the western Pacific to the eastern Pacific along the coast of South and Central America.

Rising sea surface temperatures in the eastern Pacific alters air flow patterns above it. The shifting wind patterns are responsible for the development of severe and costly thunderstorms across South America.

All of this shifting to our south ultimately affects the weather across North America as well.

During an ENSO-neutral period, winters in the Pacific Northwest are normally fairly cool and wet, while the south tends to stay much drier.

During an El Nino event, however, warm air is pressed farther northward, in turn pushing the jet stream farther to the north and dramatically changing our weather outlook.

Warmer temperatures prevail, along with diminished precipitation, both rainfall and upper elevation snows.

The end result is less runoff, shallow reservoirs and a more active wildfire season…

The southern U.S. suffers from too much moisture. This was evident last year, with damaging floods in Southern California, and deadly floods in Texas and Florida. All of that was followed by a crippling winter in New England.

The current El Nino pattern is being touted to be as strong as or stronger than the event in 1997. So what does that mean for us?

If El Nino continues through the coming winter, we could see another mild winter with warmer than average temperatures and less than average precipitation — less rain in the Willamette Valley and less snow in the mountains.

Pushing these conditions into next year would mean a warm, dry spring and summer, along with another strong fire season.

However, in recent weeks, there have been indications that the winds forcing warm sea surface temperatures eastward are weakening.

Should that continue, there is the potential for El Nino to collapse and allow us to return to a more normal, ENSO-neutral flow.

While there is still enough evidence to suggest that El Nino will continue through this winter, the word from the experts at this point: Wait and see.

The NewsChannel 21 weather team will keep a vigilant eye on this situation and keep you updated through the weeks and months to come.

Bob and Russ also will be teaming up in October to bring us the annual winter outlook forecast, as well.