Friday, January 11, 2013

2012 - A Weather Anomaly?

The National Oceanic and Atmospheric Administration (NOAA) has released its retrospective on the weather for the year that just passed and, not surprisingly, there are some interesting modern day records that have been broken.  

Let's start with this map that shows the difference from average temperature by geographic area:

Every state in the continental U.S. had an above average overall temperature for 2012.  A total of nineteen states broke new records and a further twenty-six states had one of their top ten warmest years.  The year started out with the fourth warmest winter out of the past 117 with seasonal temperatures 3.9 degrees above the average for the entire 20th century:

Please note that the map shows how 2012's average winter temperatures compared to average temperatures over the period from 1981 to 2010.  Winter 2012 was warmer than normal for one main reason; the winds of the jet stream which divide cold northern Arctic air from warmer southern air stayed further north than usual.  This impacted the distribution of precipitation with the eastern and western states getting as little as 10 percent of normal precipitation and the central states getting getting as much as 200 percent plus of normal precipitation.

New spring temperature records were set with May being the second warmest May on record.  May's high temperatures, more than 3 degrees Fahrenheit above the long-term average, contributed to the warmest 12 month period that the United States has experienced since record keeping began in 1895.  Here is a map showing just how warm May was compared to historical norms for most of the United States:

The first five months of 2012 set a new high temperature record for that time period with temperatures a whopping 5 degrees above the long-term average.  This excessive warming causes problems for the farming community; crops germinate early and insect and weed pests follow shortly thereafter at a far earlier stage than would normally be expected.

The hot dry summer of 2012 was just that, very hot and very dry.  The average temperature in July 2012 was 3.3 degrees Fahrenheit above the 20th century average, winning the award for the warmest month on record for the United States.  Here is a map showing how the central states suffered from temperatures that were up to 8 degrees higher than normal for the month of July:

Here is a map showing the drought conditions that accompanied the hot weather in mid-July:

More than 1000 counties in 26 states were declared natural disaster areas, the largest natural disaster area in U.S. history.  With the accompanying drought conditions, over 2 million acres of wildfires were recorded during the month of July, the fourth highest since 2000.

Data for the fall of 2012 shows that above normal temperatures and below normal precipitation levels  have been experienced by the continental United States as a whole.  Here is a preliminary map showing the warmer and cooler than normal regions of the United States during the period from September to November 2012:

Now, let's look at the bigger picture.  This bar graph shows that global mean annual temperature from 1880 to the present:

Here is a line graph showing the average annual temperature in the continental United States from 1895 to 2010:

Over the past century, the average annual temperature in the United States has risen by 1.2 degrees Fahrenheit per 100 years, roughly the same as the global average.

Climate is defined as the meteorological conditions, including temperature, precipitation, humidity, air pressure and wind, that characteristically prevail in a particular region averaged over a long period of time.  Basically, climate is the average of all weather conditions.  What we are seeing from this report is NOAA's summary of 2012 weather.  Eventually, all of the weather experienced in 2012 will form part of the long-term average weather that will make up climate.  Eventually, as the warmer data is averaged into the long-term equation, we may be forced to admit that global climate change is real, unfortunately, by then, it may be too late to do anything about it.

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