Wednesday, March 30, 2016

March Warmth As A Guide To Summer Temperatures

During each transition season of spring and fall, people incorrectly attempt to predict the next season's warmth or cold by using the current season's temperatures as a guide. The conversations go something like this:

"This warm March means we're in for a super hot summer" or "This cold and rainy fall means we're in for tons of snow this winter." or some other combination like this.

Does this line of thinking work?

I checked the top 10 warmest March years for 8 cities (Cleveland, Cincinnati, Detroit, Indianapolis, Cincinnati, Pittsburgh, Milwaukee and Buffalo) and ranked them. I found the top 10 warmest years that occurred the most frequently for all of the cities and plotted a summer (June through August) composite (blend) temperature map of these years weighting the more frequent--top 6--warm years higher.

Summer blend - Most Frequent Top 10 Warm March Years - Top 6 Weighted Higher
I next plotted the blend of only the top 6 most frequent years of occurrence that were previously weighted. Notice the warmth become more widespread in this blend.

Neither one of these composites above are blast furnace summers by any stretch.

The problem is that both of these composites mask the individual year extremes. Look at each of the top 5 most frequent years of occurrence?  Each summer varies a great deal. A more detailed look at March 2012 (hottest on record in northern Ohio HERE) 

When we create our summer outlook each year, we perform an in-depth analysis of specific current conditions and combine it with computer projections of these conditions into the future. We combine this with some statistical analysis (similar to the above maps) to come up with a consensus outlook. Its more complicated than saying "its warm or cool now therefore it will be warm or cool next month/next season".

Bottom line, seasonal outlooks are very complex.  Don't be fooled by monthly warmth especially in early spring. It doesn't necessarily mean that an equally warmer than normal summer is ahead.

More on the summer outlook later in April.