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Friday, June 8, 2012

Andrew Freedman: Four Major Heat Records Fall in Stunning NOAA Report

If you are not alarmed by this post, then your alarm-o-meter is broken.

Four Major Heat Records Fall in Stunning NOAA Report

Four major heat records fell in a stunning new climate report from the National Oceanic and Atmospheric Administration (NOAA) on Thursday. The lower 48 states set temperature records for the warmest spring, largest seasonal departure from average, warmest year-to-date, and warmest 12-month period, all new marks since records began in 1895. While the globe has been tracking slightly cooler than recent years — thanks in part to the influence of now dissipated La Nina conditions in the tropical Pacific — the U.S. has been sizzling. 
The average springtime temperature in the lower 48 was so far above the 1901-2000 average — 5.2 °F, to be exact — that the country set a record for the largest temperature departure for any season on record since 1895.
Year-to-Date divisional temperature rankings from NOAA. Click on image for a larger version.
Spring 2012 beat 1910, which had held the title for record warm spring, by a healthy margin of 2 °F. No doubt much of this was driven by the massive heat wave that gripped the country during March, but unusual warmth continued during April and May, albeit not as intense. Such warming trends are consistent with both the influence of manmade global warming, particularly the prevalence of record warm nighttime temperatures, and natural variability has also favored warmer-than-average conditions so far this year. Studies show that as greenhouse gases continue to increase in the atmosphere, the odds of heat extremes are growing as well.
Climate Extremes Index showing 2012 has had the most extreme weather to date for any year on record. Credit: NCDC.
According to NOAA’s National Climatic Data Center, the spring of 2012 “was the culmination of the warmest Marchthird warmest April, and second warmest May. This marks the first time that all three months during the spring season ranked among the 10 warmest, since records began in 1895.”
Des Moines, Iowa, offers a case study of just how warm it’s been. The year-to-date there has averaged a whopping 8 degrees F above average, with many other cities across the country tracking close to that figure as well.
Temperature trend chart for Des Moines, IA, showing that 2012 is the warmest year to date by far. Click for a larger image. Credit: NOAA/NCDC.
Most of the states that experienced record or near-record warmth this spring were located east of the Rocky Mountains, with 31 states setting records for warmest spring temperatures. Remarkably, not a single state in the lower 48 was cooler than average this spring, and only Oregon and Washington had spring temperatures that were close to average. Although there were exceptions, much of the country had a drier-than-average spring with Colorado, Delaware, Indiana, Utah, and Wyoming coming in with a top 10 driest spring.
The record warmth helped propel the U.S. Climate Extremes Index, which tracks the highest and lowest 10% of extremes in temperature, precipitation, drought and tropical storms and hurricanes across the contiguous U.S., to a record-large 44% during the March-May period, which was more than twice the average value. “Extremes in warm daytime temperatures (81%) and warm nighttime temperatures (72%) covered large areas of the nation” were mainly responsible for this record.
Chart showing the warmest 12-month periods on record in the lower 48 states. Click on image for a larger version. Credit: NOAA/NCDC.

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