“Average” vs “Normal”

Everyday, meteorologists talk about what is “average” or what is “normal”. For example, we’ll talk about the average or normal high and low temperature for the day. I prefer to use the term “average”, as I’m in the school of thought that questions whether there really is such a thing as “normal” when it comes to weather and climate.

Think about it… how many days each year does our high and low temperature for the day match the so called ”normal” high and low for that date. For example, today the “normal” high is 85F and the “normal” low is 62F. The chance of us hitting both (or even just one) of those numbers on any given day are very slim. In fact, I’d be willing to bet we are lucky to hit both the “normal” high and low on any given day, 5 times a year or less. (I can look it up when I have more time, maybe a future blog)

Or you can think about it in terms of rainfall. “Normally” we would expect 4.25″ of rain to fall in La Crosse during July. Well what do you think the chance of us getting exactly 4.25″ of rain this month is? We might get 4.32″ or 4.19″… but would that be normal??

These are just two examples of why I like to say the “average” high for today is 85F… and the “average” low for today is 62F. For rainfall, I would say “on average”, we can expect 4.25″ of rain to fall in La Crosse during July.

I’m not saying that using the term “normal” is wrong, it just makes more sense to me to use “average” since that’s exactly what we are doing. For example, to get the “average” high for today… we are taking all of the high temps for this date in La Crosse over the past 30 years - then taking the average to come up with a specific number.

With that said… let’s take a look at how July is comparing to average so far in La Crosse. It’s been cooler and much drier than average. The average temperature (factoring in both the high and low for each day so far) is over 5 degrees below average. Only .03″ of rain has fallen so far in July, which is .81″ below average. Since June 1st,  2.88″ of rain has fallen, but that is almost 2.00″ below average. For 2009, 12.22″ of precipitation (rain and melted down snow) has fallen, which is about 3.50″ below average.

I finally gave in and turned the sprinkler on at home for the first time. Most areas could use some rainfall as the last several rain events have either been light… or spotty and scattered so some areas picked up much more rain than others.

Here are some other “averages” for La Crosse in July that might interest you:

• Average 10 sunny days
• Average 10 cloudy days
• Average 11 partly cloudy to partly sunny days
• Average 7 days with thunderstorms
• Average 11 days with rain
• Average 4 days with a high of 90F or higher
• Average 10 days with fog
• Average dew point in July is 62 degrees (highest of all months)
• Average wind speed is about 10 mph

Only time will tell how close to “average” July of 2009 ends up being in La Crosse. Mother Nature has a lot of work to do after our “not-so-average” first week of the month.

Until next time, see you in the morning!