You all have probably heard a lot about month-to-month temperature variability in El Niño winters, but what about the finer scale details?
Well, here's what a weighted 3-week moving average composite "relative" temperature anomaly looks like for *every* moderate-strong El Niño since 1876. (Note: "East-based" El Niños and El Niños accompanied by a +IOD were weighted more in this composite).
Most of you are probably already aware that strong El Niño Decembers tend to be rather mild in the Eastern US. This chart actually shows that these anomalously mild conditions tend to be favored more in mid-late December/closer to Christmas. Early in December, there's not much signal. Of course, you'll also notice that the first 2/3rds or so of February tend to be the coldest (& snowiest!) parts of an El Niño winter!
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Here's the time series in the context of uncertainty (approximated as spread) between the 15 sites used to create this graph.
The warm periods in mid-late December and even mid-late January are significant. The mid-late January warm-up is more prevalent over the northern US/closer to New England, hardly noticeable over the southern US in the grand scheme of things.
Also notice the cool-down, centered around the 2nd and 3rd weeks of February, is
very significant, in fact, it's the most prominent feature on this entire chart.
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