wxgeek's weather-Monsoon Precip and Building El Nino

So far the North American Monsoon has been stronger than average through the end of July. The NAM officially started on June 25 this year. So far I measured 3.65 inches of precip on Conifer Mountain un July, which is well above the average of 2.8 inches in July. Many areas in AZ are also well above average precip for the Monsoon season as well. The precip across CO has greatly reduced the wildland fire risk with several counties lifting their fire bans recently.

Perhaps related to our stronger than normal Monsoon rainfall is a strengthening of positive ENSO (El Nino Southern Oscillation) condition. We have been in a negative ENSO condition for the past 2 years, also known as La Nina. Tne ENSO index is currently around +0.4 which is considered a "Nuetral" ENSO condition, but the vast majority of dynamic climate models predict a strengthening of El Nino conditions as we head into the Fall and Winter months. Most models predict we will see and ENSO index near +1.0 later this year, which would mean a weak to moderate strength El Nino for the upcoming snow season. Some models predict a strong El Nino, although they are in the minority. So what does all of this mean for the rest of our Monsoon season and our upcoming snow season ?

In general, a building El Nino in the summer produces higher than average precip for CO. We have already seen this in July, and the last 2 times we have had a building El Nino in summer, August precip has been 4.74 inches in 2006 but only 1.05 inches in 2009. So not sure how our August precip will turn out. Latest long range models build an upper ridge into the Great Basin over the next 5-10 days which would limit our precip in CO. However, models also predict a hurricane to form in teh eatern Gulf of Mexico late next week and move into southern TX/northeast Mexico. This moisture could eventually end up across NM and AZ as well as CO, so hard to tell how August will play out.

There is a very high correlation between El Nino conditions and above average snowfall for the foothills and Plains of CO, especially areas south of I-70. Over the past 20 years, we have experienced 6 seasons with a weak to strong El Nino. The average snowfall on Conifer Mountain for these 5 seasons is 226 inches, well above the average of 175 inches. The record seasonal snowfall of 280 inches on Conifer Mountain was set in the 2006/2007 season, which had an ENSO index of +1.1 (moderate El Nino). Thus, it is currently quite likely we will see above average snowfall in the foothills this coming season. In previous El Nino years, we also see a positive correlation between heavy snowfall in the Fall and Spring months, especially October, March and April.

Conversely, the CO mountains tend to receive lower than average snowfall during El Nino years. The exception is sometimes the southwest mountains, but in nearly every previous El Nino, the central and northern mountains receive significantly less than average snow.

All of this is still conjecture of course, but I for one am looking forward to a snowy Fall, Winter and Spring.
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"Climatology is what you expect, Weather is what you get".

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