Addendum to this blog entry…surprise shower activity on December 31st brought 0.09″ of rain officially to Lafayette, making 2011 the 2nd driest of all time with year end totals unofficially at 35.88″.
While the Japanese earthquake and tsunami was the natural disaster story of the year in 2011, in the U.S. droughts, floods, fires, very deadly tornado outbreaks, an East Coast earthquake and Hurricane Irene composed most of the weather/disaster headlines nationally.
Locally in Acadiana, there were some major headlines as well with a couple of weather stories related to climate rather than individual events.
The National Weather Service in Lake Charles summarizes many of the specific weather events in Acadiana with some of the top stories this year involving an ice storm, tornadoes, a river flood “that wasn’t”, a “beneficial” tropical storm and all-time records for the hottest summer and the driest year.
The first of two deadly events of the year involved an ice storm on February 3 and 4th laying down a glaze of ice 1/4″ or more across portions of Acadiana along and north of the I-10 corridor that left more than 26,000 without power and numerous traffic accidents causing one fatality.
About a month later a severe weather outbreak produced at least 4 tornadoes in Jeff Davis and Acadia Parishes including an EF2 tornado that struck Rayne. The Rayne tornado produced 111-135mph winds damaging or destroying more than 600 homes and responsible for 12 injuries and one death. The tornadic damage cost were estimated in the tens of millions.
This was the beginning of a very deadly, record breaking tornado season in the U.S. with the Mississippi and Missouri devastating EF4/5 tornadoes responsible for taking hundreds of lives and producing hundreds of millions of dollars in damage-swaths.
While a drought continued in Acadiana from the previous year, this spring we found ourselves dealing with a potential “flood of our generation” as water rose to dangerous levels in the Mississippi and Atchafalaya River Basins.
Spring floods across the Central and Northern U.S. manifested in some of the highest levels recorded in the Lower Mississippi River in April and May. This resulted in the opening of the Morganza Spillway for the first time since 1973 to relieve Mississippi River pressure from Baton Rouge to New Orleans dumping excess water into the Atchafalaya Swamp.
Fortunately the river levees held and predicted flooding inundations by the Army Corps of Engineers never materialized across both river basins. Thanks to the ongoing drought, the Atchafalaya Basin absorbed and held delivery of more than 50 Superdomes worth of water per day for several weeks as water levels met or exceeded 1973 levels.
Outside of large tracts of farmland and crops being lost fortunately there were very few homes and camps inundated by the flood water, but preparing for the flood was quite costly for many.
The Atchafalaya Flood had some positive effects helping recharge portions of the swamp and build new wetland areas along the immediate Acadiana Coast at the Atchafalaya River outlet, but the effects of additional pollutants in the Basin, if any, from the Mississippi River has yet to be determined.
The threat of flooding from the river basins eased by mid-June as heat increased and drought worsened across Acadiana.
The summer of 2011 went into the record books as the hottest on record in 118 years with June, July and August temperatures collectively averaging roughly 3 degrees above normal. Daytime highs this summer were generally 1-2 degrees above normal with afternoon heat much more expansive with the lack of frequency of typical scattered showers and storms that the area normally enjoys during the hot summer months.
Interestingly enough Acadiana’s overnight lows were even warmer averaging 4-5 degrees above normal which was likely related to less night-time evaporative cooling from less rainfall.
Heat waves and droughts work hand and hand and feed off each other, and this year that was especially true for Louisiana into Texas.
As mentioned in previous katc.com articles and the Weather Blog, the drought in Acadiana has spanned over the last two years with 2011 likely to go down in the record books as driest ever…at least in Lafayette. The year to date rainfall of 35.78″ is driest in the 118 year record barely beating out the 35.80″ that fell in 1924.
Most area-wide rain totals this year have been higher, in the 40-50″ range, which is still well below the normal of nearly 60″. Conversely there areas in Acadiana that have been drier and more desperate for the rain as well.
Including the year total rainfall in Lafayette of 42.52″ in 2010, the total for last two years is the least combined for any back to back years on record, translating to one of the worst droughts this area (in some spots) has seen in the last 100 plus years.
Usually the tropics make headlines for the year in Acadiana, but this year the main tropical story was Hurricane Irene along the East Coast.
The area did experience the first tropical storm since Hurricanes Gustav and Ike in 2008, but Tropical Storm Lee actually helped to ease the ongoing drought.
Lee struck the area as a weak to moderate tropical storm during the Labor Day Weekend slowly meandering across Acadiana for three days. The storm inflicted minimal wind damage to the area but produced 5-10″ of rain Acadiana wide.
Considering the slow movement of the storm, Lee could have produced more than 20″ of rain or more in the area, but the system never delivered on its potential.
Fortunately most of the rains that fell from Lee were also spread out over a period of time, so outside of some localized flooding, Acadiana weathered the storm fairly well.
At one point there were more than 40,000 homes in Acadiana without power following Lee, but fortunately due to the relatively weak storm, power was restored quickly in most areas in less than a day.