March 2012: warmest in U.S. history

By: Dr. Jeff Masters , 2:12 PM GMT en Abril 10, 2012

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Not only was March 2012 the warmest March in the U.S. since record keeping began in 1895, it was also the second most extreme month for warmth in U.S. history, said NOAA yesterday, in their monthly "State of the Climate" report. The average temperature of 51.1°F was 8.6 degrees above the 20th century average for March, and 0.5°F warmer than the previous warmest March in 1910. Of the more than 1,400 months that have passed since the U.S. weather records began in 1895, only one month--January 2006--had a larger departure from its average temperature than March 2012. A remarkable 25 states east of the Rockies had their warmest March on record, and an additional 15 states had a top-ten warmest March. Only four states were cooler than average, with Alaska being the coldest (tenth coldest March on record.)


Figure 1. Temperature rankings for March 2012 in the Contiguous U.S. Twenty five states set records for warmest March in the 118-year records (red colors.) Image credit: NOAA.

March 2012: most daily records broken of any month since July 1936
A wunderground analysis of weather records from NOAA's National Climatic Data Center temperature record database reveals that more daily high temperature records were broken in March in 2012 than for any month except July 1936, going back at least 100 years. Fully 11.3% of all daily high temperature records for the month of March in the U.S. are now held by the year 2012, for the 550 stations in NOAA's National Climatic Data Center database that have weather records extending back at least 100 years. The only month in U.S. history holding a higher percentage of daily temperatures records is July 1936. That month holds 14.4% of all the U.S. high temperature records for the month of July. That month occurred in the great Dust Bowl summer of 1936, the hottest summer in U.S. history.



Summer in March 2012: records not merely smashed, but obliterated
Among the 15,000 daily records for warmth set in March 2012 were 21 truly astonishing ones: cases where the low temperature for the day beat the previous high temperature for the day. It is quite rare for a weather station with a 50+ year period of record to break a daily temperature record by more than 10°F. During "Summer in March, 2012", beating daily records by 10° - 20°F was commonplace, and NOAA lists 44 cases where a daily record was broken by more than 22°F. Extraordinarily, four stations broke a record for the date by 30°F or more. Canada holds the most surreal record of this nature during the "Summer in March, 2012" heat wave: Western Head, Nova Scotia hit 29.2°C (85°F) on March 22, breaking their previous record for the date (10.6°C in 1969) by 18.6°C (33.5°F.) Canada also had several stations break their all-time warmest April temperature records in March.



Last 3 months and 12 months were the warmest on record
The previous 12-month period (April 2011 -March 2012), which includes the second hottest summer (June-August) and fourth warmest winter (December-February), was the warmest such period for the contiguous United States. The year-to-date period (January - March) was also the warmest on record. NOAA's U.S. Climate Extremes Index, an index that tracks the highest 10 percent and lowest 10 percent of extremes in temperature, precipitation, and drought, was 39 percent, nearly twice the long-term average and the highest value on record for the January - March period. The predominant factor was the large area experiencing extremes in warm daily maximum and minimum temperatures.

Analyzing the "Summer in March, 2012" heat wave
Dr. Martin Hoerling of NOAA's Earth System Research Laboratory in Boulder has posted a thorough analysis of the heat wave, which he calls, "Meteorological March Madness 2012". He explains that the event was probably a natural phenomenon, one that was predicted more than a month in advance by NOAA's long-range CFS model. A similar, though not as intense heat wave occurred in March 1910. However, he notes that the approximate 0.5 - 1°C warming in the Ohio Valley/Midwest U.S. in recent decades--due to human-caused emission of heat trapping gases like carbon dioxide--has significantly increased the odds of major heat waves occurring. He speculates that the odds of a 1-in-40 year heat wave in the Midwest may have increased by about 50% due to human-caused global warming, but that we really don't know how much global warming may have increased the odds of the March 2012 heat wave, saying "This issue of estimating reliable statistics of extreme, rare events continues to be a matter of active research." He estimates that human-caused global warming likely increased the intensity of the March 12 - 23, 2012 heat wave by about 5 - 10%, and concludes by saying, "The probability of heatwaves is growing as [human-caused] warming continues to progress. But there is always the randomness."

Jeff Masters

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Quoting SteveDa1:
Fully 11.3% of all daily high temperature records for the month of March in the U.S. are now held by the year 2012

Unreal...


Who cares, it only goes back to 1895.
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I hope this does not continue into the summer months, can anyone say widespread droughts?
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Tough times for the mountains here on the CA/NV border. Winter temps were normal (cold), but there was no insulating blanket of snow in December, January, and most of February, which is very unusual. Hiking around, I see widespread areas of frost-killed brush and brush with loads of dead leaves. This portends a scary fire season ahead.
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i love how the one state thats on the cold side is mine... thanks la nina !!
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WOW!
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What does that tell us about how thunderstorms make tornadoes?


We've known for decades that all supercell thunderstorms have a gust front, which is the boundary between the moist, warm air that is flowing into the storm and the generally cooler air coming down out of the storm. But what we noticed in several cases recently is that thunderstorms that are making, or are about to make, tornadoes, have a secondary front, which is like a second wave of air rushing down from aloft. A strong downdraft has an important function: It brings the rotation to the ground. But for a tornado to form, you still need to tilt the rotation into the vertical, and this requires a nearby updraft. The intensity of the downdrafts and updrafts is vital, because in the end there needs to be a lot of stretching, which is when you take that existing rotation and turn it into something really violent like a tornado. It's like a figure skater pulling in her arms and spinning faster and faster.

In the Goshen County tornado, we have a strong suspicion that the development of this secondary surge or front sparked the genesis of the tornado. We need to test this. If, after looking at more cases, we can demonstrate a causal link, then perhaps in the future a forecaster observing the development of a secondary surge will have an increased ability to forecast


The data analysis emerging from VORTEX2 also identifies another possible trigger, a "descending reflectivity core." What is that, and how does it work?


Some supercell thunderstorms have a descending core of intense rain and hail wrapping around the west side of the storm. That's what we call a descending reflectivity core, or DRC. This DRC drags rotating air downward from maybe four or five kilometers up and might cool the air in various places. As you drag the air downward, you create rotation and antirotation in different parts of the storm, and that seems to occur around the time of tornadogenesis. Right now these two features, the DRC and the secondary surge, hold the most hope for explaining why some supercells are able to generate rotation near the ground and why the low-level rotation is turning into a tornado when it does.

http://discovermagazine.com/2012/extreme-earth/19 -storm-chaser-looks-tornados-heart
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Fully 11.3% of all daily high temperature records for the month of March in the U.S. are now held by the year 2012

Unreal...
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Member Since: Julio 15, 2006 Posts: 170 Comments: 53613
One possible side effect to watch out for from this winter is its impact on crops. While some crops will enjoy a longer growing season, other crops require a certain amount of "chilling time" (temps under 45F) in order to have productive years. These crops include peaches, pears, plums, and apples. In some areas of the south (such as TX/LA), we didn't get much chill time, so some crops may have drastically lowered production, with high prices to follow during harvest.
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Having a one week dry spell in SE TX, hoping for next week the storm system plays out and get a few inches of rain
Member Since: Julio 14, 2008 Posts: 1 Comments: 9628
The new GFS is trickling in, i hope it matches the Euro and the CMC
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The no Winter of 2011/2012.
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the last 12 months have been warmer than normal doc
Member Since: Julio 15, 2006 Posts: 170 Comments: 53613
Thanks Dr. Masters
It certainly was warm
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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