Record Cold in a Warming World
An impressive blast of Arctic air has toppled more records for all-time March cold over the Eastern U.S., in the wake of the major snowstorm that brought 4 - 8" of snow from Missouri to Maryland. Fresh snow is very efficient at radiating heat to space, and the 3.8" of snow that fell in Baltimore on Monday helped drive the temperature down to 5°F on Monday night, tying the city's all-time March low temperature record set on March 4, 1873. The temperature eventually dipped down to 4°F Tuesday morning, breaking the March record. Atlantic City, NJ, which got 5.5" of snow on Monday, also set a new all-time cold record for the month of March on Monday night, when the temperature fell to 2°F. The previous all-time low for the month of March was 3°F set on March 4, 2009. Official records for the Atlantic City area date back to 1874.
At least five other cities have set or tied all-time March cold temperature records during the current cold wave:
Charlottesville, Virginia set an all-time March low of 1°F Tuesday morning (previous record: 7°F on March 4, 1943.)
Billings, Montana set an all-time March low of -21° on March 2, 2014 (previous record: -19°.)
Pierre, South Dakota set an all-time March low on both March 1 and March 2, dipping to -20° (previous record: -19°F on March 11, 1998.)
Flint, Michigan set an all-time March low of -16° on March 3 (previous record: -12°.)
Rockford, Illinois tied its all-time March record low of -11° on March 3.
At least five U.S. cities have set records for their coldest winter on record, as detailed by wunderground's weather historian Christopher C. Burt in his latest blog post. He has not yet compiled a list of cities that have set a record for their warmest winter on record during 2013 - 2014, but I know of at least two: Las Vegas, Nevada, and Tucson, Arizona.
Figure 1. Departure of surface temperature from average as diagnosed by the GFS model at 00 UTC March 4, 2014. A negative phase of the Arctic Oscillation (AO) allowed cold air to spill southwards out of the Arctic over the Eastern U.S., bringing temperatures up to 36°F (20°C) below average. Compensating warm air flowed northwards into the Arctic underneath a ridge of high pressure over Europe. Data/image obtained using Climate Reanalyzer™ (http://cci-reanalyzer.org), Climate Change Institute, University of Maine, Orono, Maine.
How can a planet that is warming experience record cold?
This week's impressive cold blast brings up the question: How can a planet undergoing "global warming" experience record cold? Well, it's a big planet, and the weather has naturally crazy extremes. We expect to see many locations experience all-time daily and monthly cold records each month. It's just that the number of these cold records will be outnumbered by all-time heat records, when averaged over the globe, and over decades. It is called Global Warming for good reason! A 2009 study led by Dr. Jerry Meehl of the National Center for Atmospheric Research in Boulder, CO found that in the U.S., the ratio of the number of record daily highs to lows was near 1:1 in the 1960s and 1970s, but had increased to more than 2:1 during the decade of the 2000s, due to our warming climate. The ratio for the 2010’s was approximately 2.4-to-1 for daily records, for the four years 2010 - 2013, as explained in detail at Guy Walton's wunderblog. If "business as usual" emissions of heat-trapping gases like carbon dioxide continue this century, this ratio of record highs to record lows is expected to increase to 20:1 by the year 2050, and 50:1 by 2100. So, even on planet experiencing extreme global warming, we will still see a few record low temperatures in the 22nd Century.
Figure 2. Ratio of record daily highs to record daily lows observed at about 1,800 weather stations in the 48 contiguous United States from January 1950 through September 2009. Each bar shows the proportion of record highs (red) to record lows (blue) for each decade. The 1960s and 1970s saw slightly more record daily lows than highs, but in the last 30 years record highs have increasingly predominated, with the ratio now about two-to-one for the 48 states as a whole. ©UCAR, graphic by Mike Shibao; data from a 2009 study led by Dr. Jerry Meehl of the National Center for Atmospheric Research in Boulder, CO.
Two Years Ago: Summer in March
When we do break all-time heat records in the current warming climate, we should expect that some of these new records will crush the old records in phenomenal ways. That was the case during the astonishing U.S. record-breaking "Summer in March" heat wave just two years ago, in 2012. It was the warmest March on record for the contiguous U.S., 8.6°F 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. record began in 1895, only one month, January 2006, had a larger departure from its average temperature than March 2012. Every state in the nation experienced a record warm daily temperature during March, and 25 states east of the Rockies had their warmest March on record. An additional 15 states had monthly temperatures ranking among their ten warmest. All-time March records were broken at 290 stations, with some stations breaking their all-time March record four times. There were 21 instances of the nighttime temperatures being as warm, or warmer, than the existing record daytime temperature for a given date. Four stations broke daily records by 30°F or more.
Figure 3. "This is the kind of sunset that you can expect to see in July, not in March. 77°F when I took this," said the caption on this wunderphoto taken on March 17, 2012 in Windom, Minnesota by wunderphotographer sally.
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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