Ticker for May 20, 2008

                
MESONET TICKER ... MESONET TICKER ... MESONET TICKER ... MESONET TICKER ...
May 20, 2008       May 20, 2008       May 20, 2008       May 20, 2008



Oklahoma's First 100: Right on Schedule?
(subtitled: No We Don't Get Paid Extra Each Time We Use The Word "Normal")

Well, we broke the seal on triple-digit temperatures yesterday, with a
selection of southwestern stations searing in the springtime sun:



Yesterday's weather was much warmer than the so-called normals, but, at
the same time, the arrival of 100-degree temps was perfectly normal.

Huh?

How could we be normal and warmer-than-normal at the same time?

Welcome to spring in Oklahoma.

And here's how it works: normals are just an average for conditions
over a long period of time. As we all know, Oklahoma's weather,
especially during spring, is very bipolar: it avoids normal
religiously. This week's warmth is a great example. The cooler weeks
earlier this spring are another example.

Applying the word "normal" to a field of extremes is a silly thing to
do. It's like saying "I sleep 8 hours a day and I'm awake 16, so my
normal state is two-thirds awake"!

(wait a second, on second thought, that *is* our normal state
around here, but you get the idea)

In other words, it's quite normal to be warmer than normal. This
explains why no single day has a normal high temperature of 100,
yet some place in Oklahoma tops 100 every year.

So, even though 100 isn't normal in a single-day sense, it's quite
normal in an over-the-course-of-the-year sense. And, it turns out
that we can use the same concept to define the so-called "normal"
first-100-of-the-year date. It happens to be, ironically, May 19th.
Which makes yesterday's not-normal warmth normal, *perfectly* normal!



This graph displays the historical date of the first 100 for each year
from 1895 (left side) through last year (right side). The blue bar
indicates how long the non-100 temps held out. In other words, the
taller the bar, the later the date of the first 100.

Notice that the "May 19" date is pretty useless in its own right, because
the onset-of-100s date is all over the calendar. The first 100 has
happened as early as mid-March, and as late as July 4th!

Also notice that during the mid-20th Century, the first 100 tended to
come much earlier than the long-term average. And, in recent years, the
first 100 has actually been a bit later than the long-term so-called
"normal" ... so if May 19th seems a bit early, it is, when compared to
the last 15 years or so.