July 2012 was hottest on record for Lower 48

Posted: August 10, 2012

Preheated with a mild, snowless winter and a balmy spring, the contiguous United States last month had its warmest July on record, according to the National Climatic Data Center.

The average temperature of 77.6 degrees Fahrenheit was 0.2 of a degree higher than the standard set in 1936, in the heart of the Dust Bowl era.

"It's a pretty significant increase over the last record," climate-center scientist Jake Crouch said.

Nationally - and in Philadelphia - the first seven months of the year constituted the warmest such period on record.

The 1930s and their infamous droughts have been seared in the national memory, but the '30s are meeting their match in 2012. "We're rivaling and beating them consistently from month to month," Crouch said.

In addition, the nation has undergone an inordinate number of extreme events - drought, heavy rainfall, and record temperatures - according to the climate center, a National Oceanic and Atmospheric Administration agency in Asheville, N.C.

As of last week, about 80 percent of the 48 states were at some level of drought, the U.S. Drought Monitor reported, and, believe it or not, that was a slight improvement over the previous week.

Crouch and other scientists say the national mayhem is a symptom of a warming world.

During the last three decades, global temperatures have risen about 0.8 of a degree Fahrenheit, according to data from the NOAA and NASA satellites.

The climate center's global report for July is not yet available. The satellite data released this week showed that although monthly temperatures were above normal, this was the coolest July worldwide since 2008.

That certainly was not the case in the 48 states.

"It's very similar to the Dust Bowl," said Jeff Masters, meteorologist with Weather Underground, a commercial service.

He said the groundwork for an oven-ready nation was laid by an extraordinarily mild and snowless winter and warm spring. The lack of snow cover meant lack of snowmelt.

The dry ground meant more of the sun's energy went to heating rather than evaporating moisture. That, in turn, allowed high pressure, or heavier air, to build over the middle of the nation, which discourages storms from forming.

"Whenever you have drought, that increases the chances of a hot summer," Masters said.

The heat has been extreme in parts of the West and Midwest, but plenty of it has lapped into the Northeast.

Last month, the temperature in the 48 states was 3.3 degrees warmer than the 20th century average for July, and for 32 states, this July was among their top 10 warmest.

Locally, July 2012 finished at 81.8 degrees, running out of steam before it could catch No. 1, which was 2011, at 82.4 degrees, or No. 2, 1994, 82.1. It did, however, manage to creep past 2010, 81.7.

July 2012 also tied a record for the most days of 90-plus temperatures, 21.

Only 44 days to the equinox.

Contact Anthony R. Wood at 610-313-8210 or twood@phillynews.com.

This article contains information from Inquirer wire services.

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