In our daily weather forecasting a lot of times we compare our weather forecast to what we call the climate average or “normal” temperatures and rainfall. In truth, it’s not an average that we go by in terms of daily, monthly, or seasonal temperatures but rather a statistical formula that uses a 30 year segment of climate data. The Climate Data Center and National Weather Service take the averages for the 30 years and update the numbers every 10 years, or about as often as the government takes a census of the population. The numbers are splined through the calendar year, or in other words for simplicity’s sake, the numbers are smoothed so that the averages are evened out and only gradually increase and decrease with the changing seasons. An example is the month of August which has an average high of 80 on the first and then the numbers only gradually decrease through the month, first to 79 and then 78 toward the end of the month. That’s not going by straight averages, but rather the splined statistical computation. Again, it’s just a way to keep the numbers neat and simplified. Anyway, back to our new data. Yes, we have a brand new set of climate statistics available to us that uses data from 1981-2010 and now as of today, August 1st, it’s officially being used locally with our own weather. It’s kind of exciting-like Christmas for climate geeks! Below is a chart from the NWS in La Crosse that shows the comparison of the new set of data with the previous set of 30 year data. Notice that with few exceptions the temperatures have increased over the previous data set.
Old is the 1971-2000 normals. New is the 1981-2010 normals. Red text indicated a warmer temperature compared to the old set of normals. Blue text indicates cooler temperatures compared to the previous normals. Green text indicated more precipitation, while Brown text indicates less.
More details on the new climate normals will be added to this, or other news stories, over the next few weeks. In the meantime, consult the links below for more information, or take a look at some of the new normals. Note that the normal files are not “user friendly” and its suggested that you peruse the “Read Me” text file for help in interpreting them. A more friendly interface of accessing the normals will be made available in the near future.
Posted under climate
This post was written by tschmidt on August 1, 2011