The May 1995 Louisiana flood, also known as the May 1995 Southeast Louisiana and Southern Mississippi Flood, was a heavy rainfall event which occurred across an area stretching from the

New Orleans metropolitan area The New Orleans metropolitan area, designated the New Orleans–Metairie metropolitan statistical area by the U.S. Office of Management and Budget, or simply Greater New Orleans (french: Grande Nouvelle-Orléans, es, Gran Nueva Orleans), is a me ...

into southern

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

. A storm total rainfall maximum of was recorded near Necaise, Mississippi.Lincoln, W.S
Updated Rainfall Analysis for the May 1995 Southeast Louisiana and Southern Mississippi Flooding
2014. Considerable flooding was caused by the rainfall including several record flood crests along impacted river systems. May 1995 Flood Uptown New Orleans Taxi

The flooding caused six fatalities and more than $3.1 billion in damage.THE HISTORIC SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI FLOOD OF MAY 8-10, 199

Retrieved on 2012-12-06.

Meteorological synopsis

The entire 40-hour event from the evening of Monday, May 8, through the morning of Wednesday, May 10, consisted of two distinct heavy rainfalls. By Wednesday morning, storm total rainfall amounts of were common across portions of southeast

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

and south

. A

cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Northern ...

approached the region from the west, preceded by a

squall line A squall line, or more accurately a quasi-linear convective system (QLCS), is a line of thunderstorms, often forming along or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front (which often are accom ...

. The airmass that entered western Louisiana on May 8 exhibited considerably lower

dewpoint The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will co ...

s than the tropical airmass across east Louisiana and southeast Mississippi. By the evening of May 9, the cold front dissipated in the vicinity of Baton Rouge. The remains of the front served as a focusing axis for heavy precipitation that continued into the late morning hours of May 10. An upper-level trough helped to provide upper-level support to the system. At the surface, warm and moist air moved in from the Gulf of Mexico continually during the event. The swath of highest rainfall totals was closely tied to a theta-e ridge at the 850 mb pressure surface, which stretched from the central Gulf of Mexico into the Mississippi River Delta area. During each wave of rainfall, heavy, "training" thunderstorms continued to form over the same areas for multiple hours. In the New Orleans area, pumping stations were overwhelmed and could not pump rainfall into Lake Pontchartrain as quickly as it was falling. At the time, pumping stations were only rated to pump per hour maximum.

Timeline

Rainfall totals from the first wave of the 1995 New Orleans area flood event

Rainfall totals from the second wave of the 1995 New Orleans area flood event

* Approximately 5:30 p.m. on May 7th... heavy rainfall begins across areas south of

Lake Pontchartrain Lake Pontchartrain ( ) is an estuary located in southeastern Louisiana in the United States. It covers an area of with an average depth of . Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about from wes ...

, continuing into the early morning hours of May 8th. * Early morning hours on May 8th...

Flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...

ing began in

Jefferson Parish Jefferson may refer to: Names * Jefferson (surname) * Jefferson (given name) People * Thomas Jefferson (1743–1826), third president of the United States * Jefferson (footballer, born 1970), full name Jefferson Tomaz de Souza, Brazilian foo ...

and

Orleans Parish New Orleans ( , ,New Orleans

New Orleans New Orleans ( , ,New Orleans

, Metairie,

Kenner Kenner Products, known simply as Kenner, was an American toy company founded in 1946. Throughout its history, the Kenner brand produced several highly recognizable toys and merchandise lines including action figures like the original series of ' ...

, River Ridge, and

Harahan Harahan is a city in the U.S. state of Louisiana and suburb of New Orleans. The city of Harahan is located in Jefferson Parish; its population was 9,116 at the 2020 census. Etymology Harahan was named in honor of James Theodore Harahan, presi ...

* Evening hours on May 9th... Heavy rainfall occurs across areas north of

in Saint Tammany Parish, Louisiana, including Slidell, Covington, Mandeville, and Abita Springs. Heavy rainfall also occurs across south Mississippi, especially portions of

Pearl River County Pearl River County is a county located in the U.S. state of Mississippi. The population was 55,834 at the 2010 census. Its county seat is Poplarville. Pearl River County comprises the Picayune, MS Micropolitan Statistical Area, which is inc ...

, Hancock County, and Harrison County, including

Bay St. Louis Bay St. Louis is a city in and the county seat of Hancock County, Mississippi, in the United States. Located on the Gulf Coast on the west side of the Bay of St. Louis, it is part of the Gulfport–Biloxi Metropolitan Statistical Area. As o ...

and Gulfport. * Late evening May 9th... flooding begins in the Lake Pontchartrain Northshore areas of Louisiana and also coastal Mississippi. * May 10th... severe river flooding impacts areas along the Wolf River,

Tchoutacabouffa River The Tchoutacabouffa River () is a river located in Harrison County, Mississippi. The river's mouth is located just north of the city of Biloxi at Biloxi Bay and south of present-day Interstate 10. Located at a latitude of 30.435 and longitude of ...

, and

Jourdan River Jourdan may refer to: * Carolyn Jourdan, American author *Claude Jourdan (1803–1873), French zoologist and paleontologist * David W. Jourdan, businessman *Jean-Baptiste Jourdan (1762–1833), French army commander * Jourdan Bobbish (1994–2012), ...

in Mississippi, each of which set new record stages (Wolf River flooding from Hurricane Isaac in 2012 subsequently broke the record).

Rainfall

The heaviest rainfall from the first wave of rainfall occurred on the southshore of Lake Pontchartrain in the New Orleans metropolitan area, with a secondary maxima on the northshore. Heaviest rainfall from the second wave occurred across the northshore of Lake Pontchartrain and coastal Mississippi. By May 10th, rainfall totals of 10-20 inches were common. Some notable two-day totals from the

National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...

archives and post-event surveys: * Necaise, Mississippi: 27.50" () *

Abita Springs, Louisiana Abita Springs is a town in St. Tammany Parish, Louisiana, United States. The population was 2,365 at the 2010 census, up from 1,957 in 2000. It is part of the New Orleans– Metairie– Kenner Metropolitan Statistical Area. History Abi ...

: 24.46" () * New Orleans (Tulane University), LA: 24.05" () * New Orleans (International Airport), LA: 9.67" () * New Orleans (Lakefront Airport), LA: 15.44" () * Slidell, LA: 19.09" () For both waves of rainfall, several locations neared or exceeded 24‑hour rainfall amounts estimated as having a 1% chance of being exceeded in a given year, (100 year average recurrence interval) as determined by both the NOAA Atlas 14 and reports by the Southern Regional Climate Center. The rainfall maximum near Necaise of was estimated as having only a 0.1% chance of being exceeded in a given year (1000 year average recurrence interval).

Impact

Similar floods occurred in

November 1979 Louisiana flood November is the eleventh and penultimate month of the year in the Julian and Gregorian Calendars, the fourth and last of four months to have a length of 30 days and the fifth and last of five months to have a length of fewer than 31 days. Nov ...

and November 7–8, 1989 Louisiana flood, although the May 1995 event was more extensive and costlier than both combined. It was the worst flooding the city had experienced between hurricanes Betsy in 1965 and

Katrina Katrina or Katrine may refer to: People * Katrina (given name) * Katrine (given name) Meteorology * List of storms named Katrina, a list of tropical cyclones designated as Katrina ** Hurricane Katrina, an exceptionally powerful Atlantic hurrican ...

in 2005. There has been no comparable recorded flood in New Orleans caused by rain alone. Six people died as a result of the flooding. The city of New Orleans suffered $360 million in damages, and the damage of the surrounding areas put that total above $3 billion. Some 56,000 homes were damaged in 12 parishes. Thousands of cars were flooded. 14,600 homes and apartments were flooded in

alone.

Aftermath

New pumping stations were built and canals were expanded to prevent further catastrophic rainfall floods. Some politicians began to push for pumping rain waters directly into the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

, but environmental groups argued against this plan. The flood prompted expansions and improvements of the city's drainage and pumping system, especially in the worst hit portions of the city, including improvements to the underground canals under Napoleon and Claiborne Avenues in Broadmoor and other SELA projects to improve drainage in Hollygrove connected to the 17th St. Canal.

References

External links

Rainfall Frequency/Magnitude Atlas for the South-Central United States
by Faiers, G.E., B.D. Keim, and R.A. Muller. 1997, Geoscience Publications: Baton Rouge, Louisiana, 40 pp. , in PDF form
Technical Paper 40: RAINFALL FREQUENCY ATLAS OF THE UNITED STATES
by Hershfield, David M. May 1961, Cooperative Studies Section, Hydrologic Services Division.

Marcus, Frances Frank. May 11, 1995. * {{YouTube, 0yxpju9VkQg, Television clips from WVUE-tv & WDSU-tv covering the May 1995 flooding.

20th century in New Orleans Floods in Louisiana 1995 in Louisiana