2:00 PM, Thursday, July 30, 2015.
It has been a while since I blogged, partly because the weather for several weeks has not presented any unusual temperature or precipitation extremes. Fairly typical summer weather is likely through the weekend, with only small chances for afternoon thunderstorms and daytime temperatures near or slightly above average.
I say “fairly typical” because this is normally the peak monsoon season with numerous showers and thunderstorms. The monsoon pattern is active, but mainly south of Colorado. A very slight shift in the pattern can allow the moisture to surge back up into Colorado, but that appears unlikely for at least the next few days.
The tropical Pacific Ocean is now seeing the strongest El Niño conditions since 1998. Whether that will persist into the winter is uncertain, but the odds slightly favor a strong El Niño into early 2016. El Niño is certainly a major climate influence, but it acts in concert with other periodic patterns in the Atlantic, Pacific, and Arctic regions which makes it’s specific impacts in Colorado variable. Here are the Colorado weather impacts that are typically associated with El Niño.
1. Less frequent chinook windstorms (and maybe more winter days with air stagnation).
2. Below average midwinter snowfall is favored along and north of I-70 and up into Wyoming.
3. Above average midwinter snowfall is favored in New Mexico and southern Colorado.
4. Early and late season snowfall may be concentrated into a high-impact storm. At the Boulder climate station the chance for a storm with over 12″ in one day during the early and late season doubles during El Niño compared to non-El Niño years. The last two strong El Niños were in 1982-83 and 1997-98. Both March 1983 and March 1998 were stormy along the Front Range. 1982 also brought the infamous Christmas Eve blizzard while 1997 brought the paralyzing and deadly blizzard of October 24-26th. Even some weaker El Niño years in the recent past produced memorable snowstorms in March 2003 and December 2006.