El Nino developing: what it is and what it means for Montana
Posted: Jul 25, 2012 5:06 PM by Meteorologist Mike Rawlins
Updated: Jul 25, 2012 5:08 PM
A new discussion from the National Oceanic & Atmospheric Administration shows a familiar weather condition will return shortly.
El Nino is an oscillation of the equatorial waters in the Pacific Ocean characterized by warmer than average water temperatures.
This can have significant impacts on the weather around the globe.
Trade winds blowing from east to west across the Pacific help to pile up warmer waters in the west Pacific.
During El Nino conditions, the trade winds relax, which lessens upwelling in the eastern Pacific.
Upwelling pulls up cooler water from deeper depths to the surface.
Warmer than average surface waters play can play a major role on Montana's weather.
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Climatic data shows El Nino tends to dry out the Treasure State during the winter months.
Records also indicate warmer than normal temperatures when El Nino conditions are present.
Should this pan out for Winter 2012-2013, Montana could see a worsening of the present drought conditions into the upcoming year.
Keep in mind, El Nino is only one of the factors that play into Montana's weather.
Several other oscillations can drastically affect conditions under the Big Sky.
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Here's the report from NOAA:
Over the last 30 days sea surface temperatures in the equatorial pacific have been warming up and other indicators such as sub-surface ocean temperatures and a gradual reversal in the equatorial wind and pressure fields reflect a likely progression towards El Nino.
Across the eastern equatorial Pacific ocean sea surface temperatures continue to warm, with the greatest warming occurring adjacent to the west coasts of Central and South America where SSTs have risen in excess of 1.5 degrees Celsius above the average as of the middle of July.
Farther west within the region of the eastern Pacific known as Nino 3.4, SSts anomalies varied from .3 degrees C on its west side to 1.4 degrees C at its eastern border.
Since early February of 2012, sea surface temperatures (SSTs) for region Nino 3.4 has exhibited a positive or upward trend.
15 out of a total of the 18 dynamic models predict at least a weak El Nino by August, September, October of 2012 and possibly a moderate El Nino by September, October, November of 2012.
The latest plume-based probabilistic ENSO forecast indicates virtually no chance of a La Nina for the remainder of 2012.
The model forecast does indicate a high probability of an El Nino this fall and winter.
■77% chance of an El Nino in September, October, November
■81% chance of an El Nino in October, November, December
■78% chance of an El Nino November, December, January
■69% chance of an El Nino December, January, February
The model also predicts a return to neutral ENSO conditions by the spring of 2013.
