Ticker for April 12, 2001

                
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April 12, 2001     April 12, 2001     April 12, 2001     April 12, 2001


"Normal" Oklahoma Climate to be Slightly Cooler and Much Wetter

What climatologists call the "normal" monthly and annual climate
will change when data from the 1991-2000 decade are fully processed.
The normal temperature and precipitation values are based on a 30-year
average, updated every ten years.  In other words, the 1991-2000
decade will replace the 1961-1970 decade in the new 30-year benchmark.

A preview of the coming 1971-2000 statewide normals for Oklahoma has
been prepared by Associate State Climatologist Howard Johnson.  These
values will differ slightly from the official values that will be
released by the National Climatic Data Center in coming months, but
any variance will be minimal.

The most striking change from the 1961-1990 normals to the 1971-2000
set will be that Oklahoma's normal climate will be much wetter.
More accurately, the normal statewide-averaged annual precipitation
will increase by more than two inches, which is six percent more than
the outgoing normal value.

Ten months will see increases, and two (August and September) will see
small decreases in normal precipitation.

The largest increases in normal precipitation occur in the calendar's
final three months.  December, in particular, will see a new statewide
mean precipitation of 2.04", a whopping 23% increase from the outgoing
value.

These changes reflect differences between the 1960s and the 1990s.
The sixties were somewhat dry years, when compared to Oklahoma's
long-term records.  The nineties period was the wettest decade on
record in several Oklahoma climate divisions.  The late autumn and
winter months were particularly wet during the nineties.

Changes in normal temperature will be less dramatic.  The overall
annual temperature will change very little, but some months will
change by up to a degree Fahrenheit.  April and November "normals"
will be 0.9 F and 0.8 F cooler, respectively.  February's will be
1.0 F higher.

The temperature changes are smaller because the relatively warm
nineties (compared to Oklahoma's long-term average) are replacing
the almost equally warm sixties in the calculations.

None of this affects the actual weather as it occurs, of course.  What
will change is the distance of an observed (or calculated or forecast)
temperature and/or precipitation value from the value deemed to be
"normal".

The data set is detailed in the tables below:

Mean Temperatures (F)         Mean Precipitation (in.)
Current  New     Change       Current  New     Change

January     36.4     36.8    +0.4         1.26     1.46    +0.20
February    41.3     42.3    +1.0         1.73     1.77    +0.04
March       50.7     51.0    +0.3         2.81     3.06    +0.25
April       60.7     59.8    -0.9         3.09     3.32    +0.23
May         68.7     68.4    -0.3         4.86     5.13    +0.27
June        77.0     76.9    -0.1         3.95     4.24    +0.29

July        82.1     82.0    -0.1         2.62     2.73    +0.11
August      80.8     80.9    +0.1         2.82     2.75    -0.07
September   73.0     73.0     0.0         3.87     3.80    -0.07
October     62.1     62.0    -0.1         3.07     3.38    +0.31
November    49.8     49.0    -0.8         2.42     2.78    +0.36
December    39.5     39.6    +0.1         1.66     2.04    +0.38

Annual      60.3     60.2    -0.1        34.24    36.44    +2.20