Showing posts with label biases. Show all posts
Showing posts with label biases. Show all posts

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.



Friday, April 25, 2014

Summer Outlooks Are Different Than Day-to-Day Forecasts



Our WJW FOX8 Summer Outlook first aired on Thursday, April 24th. Not long after, comments and criticism started pouring in stating in part that we should concentrate on getting the daily forecast right rather than trying to forecast the weather months out. This isn't new. It happens after each seasonal outlook.

Actual day to day weather forecasts are developed with analyzing current conditions, radar, satellite and other parameters to make a forecast for a short period of time in the future. 12 Hours, 24 hours, 36 hours, 48 hours. We utilize computer model projections as guidance. Yes, these projections are getting better as more data is utilized and plugged into faster and faster computers with more sophisticated equations.

Seasonal long range outlooks (winter weather forecast, etc) are created by looking at the ocean sea surface temperature patterns (El Nino, etc), pressure patterns over the Arctic and North Atlantic among some other long term atmospheric trends. Some scientists use solar output and other variables. The elements just mentioned are matched up with other years of occurrence.  A best possible fit is created. Sometimes this works out well.  Sometimes it doesn’t.  Again, this is a trend outlook not a specific forecast for a specific day. Individual storms cannot be seen this far out. Forecasts for specific days? Forget it. Too much randomness in the atmosphere that is way beyond our abilities. But by looking at parameters that existed in the past during other storm events, we can say that the chance of say a hurricane making landfall is greater this year than in years past. 

For most, all of these forecasts and trend outlooks are lumped into one group even though each are derived using entirely different information. I get it. Its human nature to generalize and simplify complicated subjects like the science of weather prediction. So as a result, we formulate a concrete, black and white, overly scaled down version of the weather.  Whether its a long range winter outlook, a climate average for a wedding day, the thunderstorm chances for later this afternoon, lake effect snowfall amounts or a hurricane forecast track. Its all the same animal to most. We subconsciously eliminate the nebulous science, weird looking equations and fancy internet computer animations in favor of a narrative that tells a better story.  In short, The Old Farmers’ Almanac fits with how our brains are wired.  Its simple. Its folksy with just enough science to make it credible.  Why do we continue believing the Old Farmers’ Almanac?  The simple answer is it makes us feel good!  While I love the Old Farmers Almanac for its articles, I'd trust an actual Meteorologist's forecast first.  I wouldn't preemptively dismiss the scientific explanation, ignore the random changes and replace them with the Old Farmers Almanac figuring that its more accurate.  Just saying...

So remember that Seasonal Outlooks are by their very nature formulated differently than day-to-day forecasts.  Let's sit back and see if this summer will behave like we think it will.