Masters: Midwest deluge enhanced by near-record Gulf of Mexico sea surface temperatures

Unprecedented flooding predicted for Ohio River

April 27, 2011

This week’s storm system, in combination with heavy rains earlier this month, have pushed the Ohio River and Mississippi River to near-record levels near their confluence. The Ohio River at Cairo, Illinois is expected to crest at 60.5 feet on May 1. This would exceed 100-year flood stage, and be the highest flood in history, besting the 59.5′ mark of 1937.

The latest River Flood Outlook from NOAA shows major flooding is occurring over many of the nation’s major rivers.

Multiple torrential downpours are setting the stage for more 100-year floods in the coming days, as meteorologist Dr. Jeff Masters reports today.
Extreme weather disasters, especially deluges and floods, are on the rise — and the best analysis says human-caused warming is contributing (see Two seminal Nature papers join growing body of evidence that human emissions fuel extreme weather, flooding).  Last year, we hadTennessee’s 1000-year deluge aka Nashville’s ‘Katrina’.  And  Coastal North Carolina’s suffered its second 500-year rainfall in 11 years.
Craig Fugate, who heads the U.S. Federal Emergency Management Agency, said in December, “The term ‘100-year event’ really lost its meaning this year” (see Munich Re: “The only plausible explanation for the rise in weather-related catastrophes is climate change”).
Former hurricane-hunter Masters has a good analysis of how the “Midwest deluge [is] enhanced by near-record Gulf of Mexico sea surface temperatures”:

The deluge of rain that caused this flood found its genesis in a flow of warm, humid air coming from the Gulf of Mexico. Sea surface temperatures (SSTs) in the Gulf of Mexico are currently close to 1°C above average. Only two Aprils since the 1800s (2002 and 1991) have had April SSTs more than 1 °C above average, so current SSTs are among the highest on record.

These warm ocean temperatures helped set record high air temperatures in many locations in Texas yesterday, including Galveston (84°F, a tie with 1898), Del Rio (104°F, old record 103° in 1984), San Angelo (97°F, old record 96° in 1994). Record highs were also set on Monday in Baton Rouge and Shreveport in Louisiana, and in Austin, Mineral Wells, and Cotulla la Salle in Texas.
Since this week’s storm brought plenty of cloud cover that kept temperatures from setting record highs in many locations, a more telling statistic of how warm this air mass was is the huge number of record high minimum temperature records that were set over the past two days. For example, the minimum temperature reached only 79°F in Brownsville, TX Monday morning, beating the previous record high minimum of 77°F set in 2006. In Texas, Austin, Houston, Port Arthur, Cotulla la Salle, Victoria, College Station, Victoria, Corpus Christi, McAllen, and Brownsville all set record high minimums on Monday, as did New Orleans, Lafayette, Monroe, Shreveport, and Alexandria in Louisiana, as well as Jackson and Tupelo in Mississippi.
Since record amounts of water vapor can evaporate into air heated to record warm levels, it is not a surprise that incredible rains and unprecedented floods are resulting from this month’s near-record warm SSTs in the Gulf of Mexico.

This final point is the link to human-caused climate change.
Dr. Kevin Trenberth, head of the Climate Analysis Section of the National Center for Atmospheric Research, explained this key connection between human-caused global warming and superstorms in an interview with ClimateProgress last year,:

“I find it systematically tends to get underplayed and it often gets underplayed by my fellow scientists. Because one of the opening statements, which I’m sure you’ve probably heard is “Well you can’t attribute a single event to climate change.” Butthere is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms and it’s unfortunate that the public is not associating these with the fact that this is one manifestation of climate change. And the prospects are that these kinds of things will only get bigger and worse in the future.”

Back in August, Trenberth told the NY Times, “It’s not the right question to ask if this storm or that storm is due to global warming, or is it natural variability. Nowadays, there’s always an element of both.”
Masters showed back in January the connection between high SSTs and record flooding around the world:

If we look at the departure of temperature from average for the moisture source regions of the globe’s four most extreme flooding disasters over the past 12 months, we find that these ocean temperatures ranked 2nd or 3rd warmest, going back through 111 years of history:

• January 2011 Brazilian floods: 2nd warmest SSTs on record, +1.05°C (20S to 25S, 45W to 40W)
• November 2010 Colombia floods: 3rd warmest SSTs on record, +0.65°C (10N to 0N, 80W to 75W)
• December 2010 Australian floods: 3rd warmest SSTs on record, +1.05°C (10S to 25S, 145E to 155E)
• July 2010 Pakistani floods: 2nd warmest SSTs on record, +0.95°C (Bay of Bengal, 10N to 20N, 80E to 95E)

Finally, we’ve only warmed about a degree and a half Fahrenheit in the past century.  The problem for our children and grandchildren is that, if we continue anywhere near our current greenhouse gas emissions pathway, we are on track to warm five times times that or more this century (see M.I.T. doubles its 2095 warming projection to 10°F — with 866 ppm and Arctic warming of 20°F ).

http://climateprogress.org/2011/04/27/midwest-deluge-record-gulf-sea-surface-temperatures/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+climateprogress%2FlCrX+%28Climate+Progress%29