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Friday, March 23, 2012

Jeff Masters: "Summer in March 2012" heat wave

by Jeff Masters, wunderblog, March 23, 2012

The most incredible spring heat wave in U.S. and Canadian recorded history is finally drawing to a close today, after a 10-day stretch of unprecedented record-smashing intensity. Since record keeping began in the late 1800s, there have never been so many spring temperature records broken, and by such a large margin. Airports in 15 different states have set all-time records for March warmth, which is truly extraordinary considering that the records were set in the middle of the month, instead of the end of the month. The 29.2 °C (85 °F) measured at Western Head, Nova Scotia, yesterday, was the third warmest temperature ever recorded in Canada in March, according to Environment Canada and weather records researcher Maximiliano Herrera (top two records: 31.1 °C at Alberini Beaver Creek, BC, on March 29th 1926, and 29.4 °C in 1921 at Wallaceburg). Michigan's all-time record for March warmth was toppled on Wednesday, when the mercury hit 90 °F at Lapeer. The previous record, 89 °F at Lapeer in 1910, was matched at three stations yesterday -- Ypsilanti, Dearborn, and Lapeer. The duration, areal size, and intensity of the Summer in March 2012 heat wave are simply off-scale, and the event ranks as one of North America's most extraordinary weather events in recorded history. Such a historic event is difficult to summarize, and in today's post I will offer just a few of the most notable highlights.

Figure 1. Clear skies over the eastern U.S. caused by a blocking ridge of high pressure on March 21, 2012, are apparent in this visible satellite image. The comma-shaped cloud pattern over the central U.S. is associated with a "cut-off" low pressure system. This low is moving over the eastern U.S. today through Saturday, and will bring an end to "Summer in March" over the U.S. and Canada. Image credit: NOAA's Environmental Visualization Lab, and modified by Andrew Freedman of Climate Central.

Low temperatures beating previous high temperature records for the date
I've never seen a case where the low temperature for the date beat the previous record high. This happened on at least four occasions during "Summer in March 2012":

The low temperature at Marquette, Michigan, hit 52 °F on March 21, which was 3 °F warmer than the previous record high for the date.

The low at Mt. Washington, NH, on March 21 (44 °F) beat the previous record high for the date (43 °F).

The low temperature for International Falls, Minnesota, on March 20 bottomed out at 60 °F, tying the previous record high for the date.

The low temperature in Rochester, Minnesota, on March 18 was 62 °F, which beat the previous record high for the date of 60 °F.

Breaking all-time April records for warmth in March
Not only did many locations in Canada set records for their all-time warmest March day during "Summer in March 2012," a number also broke their record for warmest April day:

St. John, New Brunswick, hit 27.2 °C (81 °F) on March 21. Previous March record: 17.5 °C on March 21, 1994. April record: 22.8 °C.

Kejimkujik Park, Nova Scotia, hit 27.9 °C on March 21. Previous March record: 22.5 °C on March 30, 1986. April record: 25 °C on April 27, 1990.

Yesterday, I reported that Halifax, Nova Scotia, hit 27.2 °C (81 °F) on March 22, 2012. Previous March record: 25.8 °C set the previous day. April record: 26.3 °C, set on April 30, 2004. However, Rob Paola, a meteorologist with Environment Canada's Prairie and Arctic Storm Prediction Center in Winnipeg, Manitoba, wrote to tell me that Halifax did not break its April record: In fact, Halifax recorded a temperature of 29.5 °C on April 28, 2009. For some reason, that stat does not show up on EC's normal/extremes climate site for Halifax, which only has data up to 2006 for extremes. More details on my blog at

Breaking daily temperature records by more than 30 °F
It is exceptionally 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 many records were smashed by over 20 °F. Two stations broke records by more than 30 °F, which is truly surreal. Western Head, Nova Scotia, hit 29.2 °C (85 °F), yesterday, breaking their previous record for the date (10.6 °C in 1969) by 18.6 °C (33 °F). Yesterday's high temperature was 24 °C (44 °F) above average. Pellston, Michigan, in the Northern Lower Peninsula -- dubbed "Michigan's Icebox," since it frequently records the coldest temperatures in the state -- hit 85 °F on March 21. This broke the previous record for the date (53 °F in 2007) by 32 °F, and was an absurd 48 °F above average.

Breaking daily temperature records nine consecutive days or more
It is extremely rare for stations with a 50+ year period of record to break a daily high temperature record for seven or more days in a row. The longest such streak of consecutive high temperature records at International Falls, Minnesota, was a 5-day period March 3-7, 2000. The city has tied or broken their high temperature for the date ten consecutive days, as of yesterday. This streak will likely end today, as the high is predicted to be 60-65 
°F, and the record high for the date is 66 °F. Chicago, Illinois, has tied or broken their daily high temperature record the past nine days in a row. This ties the nine-day streak of record highs set on August 26-September 3, 1953. Other cites that have set daily high temperature records the past nine days in a row include Fort Wayne and South Bend, Indiana. Numerous cities have broken high temperature records on seven consecutive days during "Summer in March 2012," including Gaylord, Pellston, and Traverse City in Michigan.

Figure 2. All-time high temperature records set in March 2012 for the U.S. The grey icons show locations where the March record was broken on multiple days. Image taken from wunderground's new record extremes page, using data from NOAA's National Climatic Data Center.

The big picture: the impacts of "Summer in March 2012"
I've always said living in Michigan would be much more bearable if we could just get rid of March. March weather here is always horrible, with brutal cold, high winds, damaging ice storms, heavy snow, interminable cloudy stretches with no sun, all interspersed with a few teasing warm spells. Well, this year, I got my wish. This March, we started with 12 days of April weather, followed by 10 days of June and July weather, with 9 days of May weather predicted to round out the month. This has been a huge benefit to the economy -- vastly reduced heating costs, no snow removal bills, and far fewer traffic accidents due to icy roads. However, there is major downside to the "Summer in March 2012" heat wave. The growing season is now in full swing, 5 weeks early. A damaging freeze that will severely impact the fruit industry and other sensitive plants is very likely. Indeed, the forecast calls for lows in the upper 20s in the cherry-growing region of Michigan near Traverse City on Monday night. The exceptional March warmth has also melted all the snow in the northern U.S. and southern Canada, drying out the soils and setting the stage for a much warmer than average summer, and an increased chance of damaging drought conditions. The early loss of snowpack will also likely cause very low flow rates in the major rivers in late summer and early fall, reducing the amount of water needed for irrigation of crops. Low flows may also cause problems for navigation, limiting commercial barge traffic on Midwest rivers.

Andrew Freedman of Climate Central interviewed a number of climate scientists who are experts in studying the link between extreme weather events and climate change for his post, Global Warming May Have Fueled March Heat Wave Odds

Wunderground's weather historian Christopher C. Burt will be posting a more comprehensive summary of the "Summer in March 2012" heat wave this weekend.

Have a great weekend, everyone, and I'll be back Monday with a new post. I expect I'll be hard at work this weekend, mowing my lawn for the first time ever in March! 

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