Ice pellets?

So, I have a little project going.

For a while now, I've been wondering just how accurate those seven- and fourteen-day out weather forecasts are.  So I've started a spreadsheet.

This is how I solve things...with data.  'Cause without data, all you have is conjecture and anecdotes.

I've shown it to a couple of people, and they seemed a little confused about how the spreadsheet works, so let me explain.

Short version: I'm tracking the predicted high temps for my zip code using four different websites and seeing how much those predictions change over the course of the week or two that they're predicting outward.

Longer version:  Going across the top (row 1) is a list of four websites.  Row 2 then are the specific links to those websites' long-term forecasts (as long-term as they happen to offer) for my zip code (45069).  Row 3 then is the website's predicted high temperature for 45069 as of how ever many days out from that specific date - as well as the actual and average historic high temperature according to official Cincinnati records.

Now, to the actual data.  Take a look at December 1, for example (row 31).  The actual high temperature for December 1 was 33 degrees (Fahrenheit, of course).  As of November 30 (the day before December 1, marked in the High 1 day out column), weather.com predicted that the high temperature was going to be thirty-two degrees.  The day before, they predicted that December 1 would be 36 degrees.  As you slide to the right in row 31, you see the predicted high temperature for December 1 as we go backward in time until the first day that December 1 showed up on weather.com on November 22 and was supposed to have a high of 43 degrees.

The next set of columns does the same thing for AccuWeather.com, then WeatherBug.com, then WeatherUnderground.com, and finally the average high temperature for 45069 based on the past however long data has been kept.

(Longer version all done now.  You can come back.)

I don't necessarily know what I'm going to get out of the data just yet.  I've promised myself that I'm going to do this for 120 days before I come to any specific conclusions.  I have noticed that AccuWeather's fourteen-day out forecast shows a lot more variation in the 14-days out time than it does when it's only a couple of days out.  I highlighted a couple of dramatic changes that AccuWeather showed.  December 7 was supposed to be 35 degrees as of 13 days out but moved to 59 degrees as of 12 days out - a change of 24 degrees.  The same kind of thing happened for December 2 when 14 days out, it was supposed to be 60 degrees, but the next day the high was only supposed to be 37 degrees - a 23 degree swing in a day.  The most dramatic change I've seen from the other sites is six degrees from Weather.com

No big conclusions yet or anything...just throwing it out there that I'm working on this because...um...because I...

Correct...

Oh, and today we're supposed to have ice pellets.  WeatherUnderground says so.

At least that's what WeatherUnderground said on Sunday morning when I typed up this post.

PS - I decided to chart only the high temperatures for the various forecasting sites because (a), it's an easy thing to compare quantitatively as opposed to precipitation which comes in weird % chances and everything and (#2) it's really easy to get and type up at a glance.