Today is August 1, 2011, so our climate normals have changed.
We meteorologists have been using relatively old records to determine our average high/low temperatures, precipitation and so on. These records were based from the year 1971 to the year 2000. Beginning today, normals will be from 1981-2010.
What’s going on here? The term “normal” – according to NOAA’s National Climate Data Center (NCDC) – is technically “the latest three-decade averages of climatological variables, including temperature and precipitation.” So normal, for NCDC, is really an average of the past 30 years – the previous three completed decades.
So now once every decade NCDC re-calculates the average and calls it our “normal.” Beginning August 1, we are using 1981-2010.
The NCDC is now using this new 30-year average for various reasons:
- Stations may have relocated
- Instrumentation at various locations have been upgraded or changed
- Changes in methodology
- It will include a suite of metrics, including daily probabilities of precipitation with month-to-date and year-to-date precipitation normals.
You can learn more about the climate normals by visiting the NCDC.
You can also locate the normals from each state through 1981-2010 from the Department of Atmospheric Sciences at the University of Washington.
Matt Daniel is Meteorologist for WBRC in Birmingham, Alabama. A self-described "big weather and music geek," Matt has a passion for helping to keep people safe when severe weather strikes and says if you don't have a NOAA Weather Radio ... you should get one.