wxgeek-North American Monsoon and El Nino Outlook

Some interesting data is emerging from the equatorial Pacific Ocean. There is now good confidence that significant warming in the central and eastern Pacific is taking place, and a very significant warming of water just beneath the surface is present. The last time such a situation was observed was in the Spring of 1997, and the most intense El Nino of recorded history occurred that Fall and Winter. There is now a better than 60% probability that a moderate to strong El Nino will develop by this Fall and persist into Winter of 2014-2015. If this does indeed occur, it will likely have implications for snowfall for eastern CO next season. In our foothills, when any strength El Nino has occurred, we have received above average snowfall 100% of the time since 1993. There have been 6 El Nino episodes since 1993 when records of snowfall began on Conifer Mountain, and in each event, snowfall was above the 21 year average. During these events, average snowfall on Conifer Mountain was 226 inches, well above the 170 inch average. The highest snowfall occurred during the 2006/2007 season when 280 inches fell. The lowest snowfall during an El Nino event was 194 inches in 2004/2005, and that was a weak El Nino event. It is still too early to predict the actual strength of the coming El Nino, but the odds are quite good we will see above average snowfall next season. This usually also implies above average snowfall for most of eastern CO, including the Urban Corridor and plains. For the mountains, El Nino events sometimes provide less than average snowfall, especially for the northern and central mountains, while the southwest mountai9ns can do better.

A developing El Nino can also have implications for our North American Monsoon (NAM), which usually begins in early July and extends into early September. The link below is a nice article detailing the relationship between a building El Nino and the NAM. In general, a building El Nino usually enhances precipitation associated with the NAM, so we can likely expect higher than normal precipitation in July and August this year. Normal precipitation for July and August is 5.75 inches on Conifer Mountain (records since 2006). In years that preceded an El Nino, precipitation was 7.5 inches in 2006, and 6.3 inches in 2009, so definitely above average. The relationship makes sense, as warmer than average water builds into the eastern Pacific, this provides additional moisture and energy for the monsoon. This is generally good news for fire season, as fire danger typically lowers significantly once the NAM begins in Colorado due to increased precipitation, higher RH values, and lower temps due to increased cloud cover. The potentially down side is the potential for flooding increases. For this year, streams will begin at higher than average levels due to the higher than average mountain snow pack, and later than usual melt. If strong thunderstorms drop large amounts of rain in a short time, flash flooding potential will increase in areas already prone from last Septembers flooding.

Adapting to Mother Nature is always a balance, as we have had recent devastating floods and fires, as well as a significant drought in our state. What is needed in one area may be problematic to another.

North American Monsoon Outlook
http://www.srh.noaa.gov/images/abq/Brie ... oon%20(NAM)%20Outlook.pdf

El Nino Outlook
http://www.cpc.ncep.noaa.gov/products/a ... odisc.html

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"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

I wouldn't mind a little more moisture. Our pond has been dry the last few years. Would be good to have the ducks and frogs return.