The Arizona Daily Sun published this article over the weekend: Forecasters: Wet Summer and Winter likely in Flagstaff. This article hints at El Nino as the cause for both extra rainfall this summer and more snow next winter. About a month ago I started to look into El Nino’s effects on Flagstaff’s summer precipitation. My hypothesis was that El Nino actually lowered rainfall amounts in the summer.
Digging into the data since 1950, there really isn’t much difference between the over all normal for 1950-2010 and any of the El Nino averages based on the strength of the El Nino. There are huge swings in the summer (June-September) rainfall amounts. Just to make the point, The El Ninos of 1957 and 1982 are both strong. They produce 4.81 and 13.42 inches of rainfall. The El Ninos of 1986 and 1991 are both moderate strength. They produced 20.64 and 3.53 inches of rainfall. The weak ones are all around 7-8 inches of rain. It looks like anything goes with El Nino Summers.
There is more than just El Nino driving the events for the year. The Climate Prediction Center still has Flagstaff in the above average rainfall zone for the summer. They should have an updated model later this week.
On a side note, I noticed last night that AccuWeather.com had a thunderstorm in the long-range outlook for Flagstaff on June 24. It’s gone this morning.
|El Nino average||0.41||2.33||3.02||2.11||7.87|
|Strong El Nino Average||0.86||1.78||2.37||3.22||8.22|
|Moderate El Nino Average||0.28||2.59||3.38||1.72||7.97|
|Weak El Nino Average||0.15||2.42||3.05||1.61||7.23|