Army Corps Opens Bonnet Carré Spillway; a January Subtropical Storm in the Atlantic?

At 10 am CST January 10, 2016, the U.S. Army Corps of Engineers opened the gates on the Bonnet Carré Spillway in St. Charles Parish, Louisiana to allow flood waters from the swollen Mississippi River to flow into Lake Pontchartrain. This is the earliest that the Corps has been forced to open the spillway, and just the 11th time since it became operational in 1931 that it has been used. The only other time the spillway has been opened in January was back in 1937. All of the other openings have come in spring or early summer. Opening of the spillway is expected to keep the Mississippi River below its 17-foot flood stage in New Orleans--just 3 feet below the tops of the levees. The river is expected to crest in New Orleans on Tuesday, January 12. There is also chance that the Corps will be forced to open the Morganza Floodway in Pointe Coupee Parish northwest of Baton Rouge, which would divert water from the Mississippi River down the Atchafalaya River. This floodway has been opened only twice--in 1973 and 2011--and has a considerably higher cost of being opened than opening of the Bonnet Carré Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Floodway. The Sunday morning forecast from the NWS River Forecast Center predicted that the Mississippi River would crest at Red River Landing, just above the Morganza Floodway, on January 18. The predicted crest of 61.0' is just 2.4' below the all-time record crest of 63.39' set on May 18, 2011, when the Corps was forced to open the Morganza Floodway in order to relieve pressure on the Old River Control Structure. The earliest the Corps would open the Morganza Floodway would be Wednesday, January 13.


Figure 1. Hundreds of people, some parking a mile or more away, trekked to the Bonnet Carré Spillway to view its historic opening on January 10, 2016. Image credit: Bob Henson.

An eyewitness account from Bob Henson on the opening of the Bonnet Carré Spillway
My fellow blogger Bob Henson happened to be in the New Orleans area on Sunday, ahead of this week's annual meeting of the American Meteorological Society. He provided this first-hand report: "Chilly north winds were whisking across the bayou as hundreds of people streamed toward the Bonnet Carré Spillway. I was glad I brought a heavy coat from Colorado! The best viewing was on the outlet side. After a press conference with several speakers, including New Orleans mayor Mitch Landrieu, U.S. Corps of Engineers workers began the laborious process of using cranes to carefully pull the long wooden pins, called needles, upward from the control structure, one by one. About 8,000 cubic feet of water per second was already forcing its way through the crevices between needles. As each needle was removed, more water cascaded from the Mississippi into the outlet flowing toward Lake Pontchartrain. It was fascinating to watch the whole process unfold at its own deliberate pace, and to hear the gradually increasing roar of the water. I also loved the slice of Louisiana life carved out in this very public event. Despite all the horrors of Katrina, and what one person characterized as a ‘love-hate relationship’ with the Corps of Engineers, the mood here was very upbeat. This time, the system was working as it was meant to. Even the winter chill added a touch of novelty, as it underscored the unusual timing of this massive flood crest. I’m feeling incredibly lucky that the timing coincided so well with my arrival here for this week's American Meteorological Society (AMS) Annual Meeting--which seems to be so often cursed with bad weather, but not with historic high water!"


Figure 2. The opening of the Bonnet Carré Spillway was a spectacle in itself. Crowds watched as wooden pins called needles guarding the Bonnet Carré Spillway were methodically removed.Image credit: Bob Henson.


Figure 3. Extracting a needle--very carefully--from the Bonnet Carré Spillway. Each of the 350 concrete bays holds 20 needles. Image credit: Bob Henson.


Figure 4. Crowds lined the slopes of the outlet between the Mississippi and Lake Ponchartrain. Image credit: Bob Henson.


Figure 5. On the Mississippi side of the Bonnet Carré spillway. Is this Louisiana or Minnesota?!


Video 1.  Two work crews remove pins from two bays of the Bonnet Carré Spillway.


Video 2.  Comments from New Orleans native Lisa Arcoleo.


Video 3.  Comments from Sabina Miller (@sweetsabinas), Thibodaux, LA.


January subtropical storm possible in the Atlantic late this week
In the Atlantic, a powerful nontropical low is stirring up the waters east of Bermuda with a large area of strong winds, some as high as 75 mph (Category 1 hurricane-force!) Models continue to move this system toward the southeast and then east this week, which could put it in a more favorable environment for subtropical development. Ocean temperatures are at near-record warm levels for this time of year in the waters east of Bermuda (about 3 - 4°F above average), which is just high enough so that a pre-existing storm like this one, which has been cut off from the jet stream and lingers over these marginally warm waters for a few days, has the potential to become a subtropical storm. On Sunday afternoon, the National Hurricane Center gave 2-day and 5-day odds of this system developing into a subtropical storm of 20% and 40%, respectively. Regardless of development, the storm may bring heavy rains and strong winds in excess of 50 mph to the Azores Islands on Friday.


Figure 6. MODIS satellite image of the low pressure system east of Bermuda that was generating hurricane-force winds on the afternoon of January 10, 2016. Image credit: NASA Worldview.

A January named storm in the Atlantic--how rare?
Only one January tropical storm has formed in the Atlantic since record keeping began in 1851--an unnamed 1938 hurricane that became a tropical storm on January 3 well east of the Lesser Antilles Islands and lasted until January 6. There has also been one subtropical storm to form in January: Subtropical Storm One of January 18 – 23, 1978. Two other named storms that formed in late December managed to last into January, though--Tropical Storm Zeta, which formed on December 30, 2005 and survived until January 7, 2006, west of the Cape Verde Islands, and Hurricane Alice, which formed on December 30, 1954, and tracked west-southwest into the Caribbean, where it dissipated on January 7, 1955.


Figure 7. VIIRS visible satellite image of Tropical Cyclone Ula taken on January 10, 2016. At the time, Ula was a Category 4 storm with 130 mph winds. Image credit: NASA Worldview.

Ula becomes Earth's first Category 4 storm of 2016
Tropical Cyclone Ula became Earth first Category 4 storm of 2016 on Sunday, hitting sustained wind of 130 mph in the South Pacific waters about 300 miles east-northeast of New Caledonia. Ula is headed poleward on a track which should miss any populated islands, fortunately. Ula passed near Vanuatu's southern islands after hitting Fiji and Tonga last week. Ula was at Category 2 strength when it hit Tonga, causing widespread damage, with roofs ripped from homes and utility lines downed by strong winds. No deaths or injuries have been reported from the storm, though.

The Southern Hemisphere’s annual tropical cyclone season, which peaks in February - March, has gotten off to an unusually slow start. Ula reached hurricane strength on December 31, becoming the latest-forming first hurricane-strength tropical cyclone of a Southern Hemisphere tropical cyclone season since the 1987-1988 season, according to CSU’s Dr. Phil Klotzbach.

Tropical Storm Pali meandering in Central Pacific
The earliest tropical storm on record in the Central Pacific, Tropical Storm Pali, had 50 mph winds on Sunday evening as it meandered over the waters about 1,450 miles southwest of Honolulu, Hawaii. Pali is not a threat to any land areas.

We'll have a new post by Tuesday morning.

Jeff Masters and Bob Henson