NASA Analyzes Weather Event That Caused Deadly Louisiana Flooding

NASA's IMERG data from Aug. 8 to Aug. 15, 2016 showed over 20 inches (508 mm) of rainfall was estimated in large areas of southeastern Louisiana and extreme southern Mississippi. Even greater rainfall totals of 30 inches (762 mm) were indicated in a small area of Louisiana west of Lake Pontchartrain. Credits: NASA/JAXA, Hal Pierce

NASA’s IMERG data from Aug. 8 to Aug. 15, 2016 showed over 20 inches (508 mm) of rainfall was estimated in large areas of southeastern Louisiana and extreme southern Mississippi. Even greater rainfall totals of 30 inches (762 mm) were indicated in a small area of Louisiana west of Lake Pontchartrain. Credits: NASA/JAXA, Hal Pierce

Record-setting rainfall and flooding in southern Louisiana have been calculated at NASA with data from satellites.

An extremely severe rainfall event hit the states of Louisiana and southern Mississippi when a very slow moving low pressure system continuously pulled tropical moisture from the Gulf of Mexico.

Measurements by the Global Precipitation Measurement or GPM mission core observatory satellite showed that rainfall intensity within the low pressure system actually increased on Aug. 12 as the low pressure area bringing the rainfall settled over southeastern Louisiana. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency JAXA.

At least 4 people have died in record flooding after the unusually heavy rainfall starting falling the week of Aug. 8. More than 27 inches (686 millimeters (mm)) of rain have been reported in the area. This is the second time this year that record flooding rainfall has hit Louisiana. At least 27 inches (686 mm) of precipitation was also reported in Louisiana during the middle of Mar. 2016 and also caused record flooding.

At NASA’s Goddard Space Flight Center in Greenbelt, Maryland, NASA’s Integrated Multi-satellite Retrievals for GPM (IMERG) data were used to make estimates of total rainfall over the northern Gulf of Mexico during the period from Aug. 8 to Aug. 15, 2016.

The IMERG data showed heavy rainfall totals moving toward the northwest from the Florida Panhandle into the central northern Gulf coast. Over 20 inches (508 mm) of rainfall was estimated in large areas of southeastern Louisiana and extreme southern Mississippi. Even greater rainfall totals of 30 inches (762 mm) were indicated in a small area of Louisiana west of Lake Pontchartrain.

Heavy rainfall and flooding is now predicted to occur northward into the Mississippi valley as tropical moisture continues to be transported northward and interacts with a nearly stationary frontal system. Heavy rainfall has also recently affected southeastern Texas and western Louisiana.

The National Weather Service (NWS) in New Orleans, Louisiana noted in a forecast discussion on Aug. 15, “As historical and devastating river flooding continues over areas between Baton Rouge and Lake Maurepas, the weather has returned to a more typical summer pattern with isolated to scattered showers and thunderstorms developing with daytime heating.”

NWS also noted that several of the rivers in and around the greater Baton Rouge area still remain at high levels after peaking at record or major crests. NWS noted that several points downstream and close to Lake Maurepas still have a way to go before broad cresting. NWS New Orleans cautioned that some locations will also undergo backwater flooding well away from the main streams, so this event remains in full swing.

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65 thoughts on “NASA Analyzes Weather Event That Caused Deadly Louisiana Flooding

  1. predicted to occur northward into the Mississippi valley…
    Impossible, we were told that was permanent drought

  2. Warmistas will be all over this one. Just would have been some drizzling if not for climate change.

  3. An honest question. (Honestly.)
    “Record setting”. We know that temperature records have been fiddled with. Have flood/precipitation records suffered the same fate?
    Please don’t misfunderstand me. An inch more or less doesn’t make much difference to those effected now. My question is asking if this is “hyped”. That is, wanting to add the “est” to an event that they’d imply was somehow Man’s fault

    • I lived in LA for 37 years prior to moving to the midwest. I witnessed two similar events in the 1980’s. One was a 24 inches in 1 day weather event that brought extensive flooding across S. Louisiana. The other was associated with hurricane Juan. There are numerous similarities of the current weather and Juan. In both cases a tropical event met a cold front that produced near stationary heavy rainfall. Juan actually made land fall three times, with the cold front pushing it back offshore where it strengthen and made land fall again and again. I recall over 24 inches of rain fell that week.
      I recall my father talking about a flood in the 1940’s. During that flood they could take a boat across the farm land of S. W. Louisiana, clearing the barbed wire fences in the process.
      It’s happened before and it’ll happen again.

      • Yes, in may 1995 we got 18 INCHES one evening from a “train effect” in just THREE HOURS(!) We got soaked, we dried out and life goes on… (this sort of thing happens all the time)

    • People can fake and hype temperature data on paper, but they can’t fake several feet of water that is inundating thousands of square miles that have never flooded in recorded history.

      • The problem is that the nature of the flood plain has changed dramatically in recent decades.
        Land has been paved over. Some streams have been blocked, others have been dredged.
        It’s quite possible for the same amount of rainfall to cause more flooding now compared to earlier times.

      • Flooding has certainly been made worse because of construction, but the vast majority of what flooded here was rural.
        In any case, the rainfall area, severity and length of time for this even was stated to have been unprecedented in recorded memory, and that’s why the flood waters came within two streets from my house, which is over 5 miles from the river and twenty-some feet above it. If the river had crested just a few hours later than it did, I would have flooded, too.

  4. This event is inevitably going to be trumpeted from the rooftops by the GWAlarmists as yet further proof to support their cause. Had this happened in say, Banglahesh, residents could be drowning in thousands, and no-one would take much notice.
    My point (thanks Bohdan!) is this: there are extreme weather events *somewhere* on this planet at any one time (think Bell-Curve distribution). While the ones affecting wealthy nations are deemed AGW-generated disasters, it’s not newsworthy when it affects only the 3rd. World. See recent pics of a Bangladeshi(?) miserably pushing his laden-bike with water up to his knees. Had this happened in the SE States, the Alarmists wd be dancing in the streets (dry ones … someplace removed) celebrating another point-proven according to their perverted view of affairs. Their framework of reference (rich nations only) excludes the multitude of other natural disasters occurring (normatively, at ‘tail-ends’ of the distribution curve) elsewhere. For every one “catastrophe” in Alabama, there are likely scores of others that (conveniently) don’t get media coverage AGW Alarmists want to covet natural disasters that only apply on their non-3rd.World turf, where their perverted message gets maximal clout via a complicit media seeking to increase sales thro’ sensationalism.

  5. We [had] 4.6 inches today, just east of San Antonio. That’s about twice as much as a typical whole month.

    • I don’t have the raw data, but roughly speaking the maps of this event showed massive rainfall over at least a 100 mile by 100 mile area. 200 square miles is nothing compared to that.

      • I was actually being conservative. Take a look at the flood maps for the following parishes: East Baton Rouge, Livingston, St. Helena and Tangipahoa. The blue regions are under estimates of where it flooded.
        http://www.lsuagcenter.com/topics/family_home/home/design_construction/laws%20licenses%20permits/getting%20a%20permit/your%20flood%20zone/flood_maps
        Those four parishes were just to be declared a major disaster, since then other parishes have gone under. For example, you can now also add Ascension Parish to the list of flood maps, and FEMA is going to increase the number by up to 30 parishes, which is close to half of the state.
        http://alerts.cnn.com/2016/08/15/us/louisiana-flooding/index.html

      • Before FEMA, no one would’ve bothered about flooding in Louisiana. Historical has little meaning in this regard.
        Citing parishes getting called disaster areas as something new is sophistry.

        “Even greater rainfall totals of 30 inches (762 mm) were indicated in a small area of Louisiana west of Lake Pontchartrain.”

        “were indicated”? Well, that’s a new phrase. Meaning their ‘model’ indicates 30 inches. Rain that fell into the swamps west of Lake Pontchartrain.
        If you check the map there is another lake just west of Lake Pontchartrain, called Lake Maurepas with swamps surrounding it.
        Too much rain here drains out through Lake Pontchartrain via the Rigolets into Lake Borgne which just happens to border on the Gulf of Mexico.
        Since mankind saw fit to channel the Mississippi River and deprive surrounding swamps, bayous, natural levees of the material they require to continue the maturation process.
        So much so that Louisiana is currently losing “Louisiana has lost up to 40 square miles of marsh per year for several decades“.
        Perhaps all of this rainfall, will help to refurbish a small portion of the wetlands that man has ignorantly destroyed with their shallow understandings of weather, water and soil.

      • Before man modified the rivers, most land down here wasn’t of much use for anything but agriculture, and that was iffy. In fact, river navigation for trade was iffy. Do you suggest we revert South Louisiana back to its natural state? And give up the Mississippi River transportation corridor?
        It’s one or the other, really?

      • Larry Fine, rainfall causes flooding events. But keep in mind that local rainfall isn’t necessarily the cause of local rainfall flooding.
        You can have flooding even where there isn’t rainfall. A flooded river doesn’t suddenly return to its banks when it hits a Parrish that otherwise hasn’t had a rainfall bad enough to cause flooding.
        “The blue regions are under estimates of where it flooded.
        http://www.lsuagcenter.com/topics/family_home/home/design_construction/laws%20licenses%20permits/getting%20a%20permit/your%20flood%20zone/flood_maps
        No. The blue regions are where flood insurance maps have been updated since 2003. Typically some properties got better, and others got worse. We have new technologies for mapping like LiDAR and updated benchmarks (permanent benchmarks in swampy regions obviously don’t hold their set elevation over time) so that the maps are more accurate. FEMA is updating them continuously.
        And floods/flood zones aren’t just based on rainfall. Development upstream impacts them greatly.
        You are right that the rainfall event covers more than 200 sq miles, but you are so very wrong on a number of other ideas.

      • Michael,
        The blue area is basically where it was estimated to flood in the event of a 100 year flood. I said that those areas are under estimated for this event. In other words, this was greater than a 100 year flood event.
        I ground truthed some of this myself, and I heard the former state climatologist say basically the same thing I did. I don’t see what your problem is with these facts.

  6. Averages and Extremes for August 15:
    Averages and Extremes Value Year
    Average Maximum Temperature 25.9°C
    Average Minimum Temperature 14.3°C
    Frequency of Precipitation 33.0%
    Highest Temperature (1938-2012) 34.4°C 1938

    Highest Temperature 1938-2012?
    1938

      • Wetish
        Warnings
        9:50 PM EDT Monday 15 August 2016
        Rainfall warning in effect for:
        Innisfil - New Tecumseth - Angus
        Orangeville - Grand Valley - Southern Dufferin County
        Shelburne - Mansfield - Northern Dufferin County
        A significant widespread rainfall is expected beginning overnight or early Tuesday morning and ending Tuesday evening.
        The rain will be heavy at times with general amounts of 40 to 60 mm likely. A few thunderstorms are also expected.
        The system responsible for this rainfall is a moisture-laden disturbance from Texas.
        Heavy downpours can cause flash floods and water pooling on roads. Localized flooding in low-lying areas is possible.
        Rainfall warnings are issued when significant rainfall is expected.
        Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to storm.ontario@ec.gc.ca or tweet reports to #ONStorm.

  7. Couldn’t be because of the wholesale drainage of swamps from the Civil War on keeping rain and runoff in development filled flood channels that turn into class 5 rapids instead of being allowed to mellow out over thousands of shallow square miles to sleepily settle back into Earth. Nah.

  8. The flood waters are finally falling in Baton Rouge, but that just means that Ascension Parish, just south of the capital city, is currently going under. Even further south, people are packing up and sand bagging for their lives. This is a rolling event that’s far from over.
    I read that records were broken at 15 river gauges, and several were broken. As the the former state meteorologist said, this is going to be studied for a while.

  9. By the way, the national media is under reporting this event by a long shot.
    In just one parish, 35,000 people who hadn’t already evacuated had to be rescued, and those rescue efforts continue. 90% of homes in one town have taken on water, and approximately 75% of people in the parish have lost everything. No valid numbers yet for other parishes, and parishes to the south are still seeing rising flood waters, as the deluge continues plowing its way to the Gulf of Mexico.
    Looking on the bright side, many of those people are poor by national standards, so donations will go a long way.
    http://www.wbrz.com/news/90-percent-of-denham-springs-flooded-rescues-will-continue-tuesday

    • Southern, uneducated folks who carry guns and vote Republican…the national media doesn’t care about them. When they start covering it, they have to keep themselves from writing that they think those people deserve it.

      • Quite true.
        In fact, some of the early national coverage that I saw was only about how some celebrity’s home had flooded. 4 trillion gallons of water falling on 1+ million other people’s homes wasn’t important.
        Trivia: That’s equivalent to New Orleans’ indoor water usage for 320 years.
        But there was some good news yesterday. Taylor Swift donated $1 million to the victims, which also means that many people who hadn’t even heard about this unfolding major disaster will now.

  10. Have any of our august contributors an opinion on the actual physical mechanisms that caused (enabled) this event?
    There must have been a highly ‘saturated’ (yet stable) air mass to deliver such volumes of rain, where did it come from, what caused it to cool to condensation point? Why did the ‘jet stream’ not tear away the tops of the clouds at 16k? etc etc etc

    • Charles,
      I watched the weather as this moved into Louisiana, and they said the Low formed onshore on the northeastern Gulf of Mexico. Then a stationary High on the East Coast slowly pushed it into Louisiana, but it was moving at walking speed because the stationary jetstream was hanging over the Plains was pushing against it, too.
      Then prevailing winds pulled moisture into the system from the Atlantic and Gulf of Mexico over several days.

    • I was paying more attention to FL predictions, but I think Mike’s Weather Page / Spaghetti models was reporting on the potential for it a week ahead.

  11. This is typical of the types of severe weather event expected in a warming world…
    (Yes, elsewhere you’ll still have drought)
    https://www.pik-potsdam.de/news/press-releases/record-breaking-heavy-rainfall-events-increased-under-global-warming
    This is the same thing which now regularly produces record floods in winter and summer surface flooding with record rainfall in the UK… (15 out of last 16 years in the UK)
    Time to start hardening your infrastructure, not to be explaining it away

    • Hmm. That is at odds with IPCC & NCA, who have both said that there is no global or US trend in floods.

    • Evidence-free Warmist doctrine. And what the hell does “hardening your infrastructure” have to do with the slight warming we’ve experienced? Nice little red herring there griffy.

      • We do need to harden infrastructure, but more for demographic reasons than climate.
        As populations expanded, and time between floods is often decades, more people have built more in flood plains.
        Then, governments make misguided decisions, like to effectively stop dredging rivers, as in the UK. Or relaxing zoning laws. Or to stop building dams because the pundits predict drought, like in Australia.
        More flood control is needed. More control over building in at risk areas is also needed. Simply forcing owners to carry flood insurance is the simplest, instead of relying on the government to rebuild for you.
        Building dry reservoirs, like Calgary is now doing, also helps. It’s easier than moving hundreds of sky scrapers.
        But, if you build on a flood plain, it will flood. One should not be surprised when it does.

      • The flooding in the UK has reached the point where new flood defences installed to block a 1 in 100 year flood after 2005 floods were overwhelmed last winter.
        The businesses which had ‘hardened’ their premises after 2005 were back working in a couple of days – the rest are still refitting.

    • Fascinating. An event that occurs naturally every few decades is proof that the world is warming?
      Regardless, whether it’s drought, flood, heat or cold, everything has been claimed as proof of a warming world.
      Your devotion to your peculiar religion is duly noted, and ridiculed.

  12. Big deal. Tropical storm Claudette in 1979 put down 43 inches not far to the west in Alvin TX (near Houston).

    • Actually, around Friendswood (near Alvin) people reported 60″ in their rain gauges from Claudette. The official weather station gauges could only hold 40″.

  13. So no one is considering the stuff jasper Kirkby at Cern talks about, air traffic contrails causing a lot more moisture to be airborne, and this surely affects precipitation, floods would be one outcome, drought another.
    Whether intentional or not, aircraft are dumping lots of aerosols into the atmosphere.
    Tell me how this does not affect precipitation? An easier question.
    http://contrailscience.com/skitch/contrails_southeast_lrg.jpg
    http://metabunk.org/sk/skitched-20130827-051029.jpg

    • To clarify more nuclei means more spread out moisture and less chance for rain, until it eventually comes together, and you get a lot more rain than normal. The very process for preventing rain, which China has carried out for their Olympics, can create flooding elsewhere.
      This messing with weather is insane, and the outcomes of this will be blamed on CO2

  14. It’s summer. It’s near the Gulf. There is the sea breeze. It’s North America’s version of the South Asian Monsoon. Now, add to that, some circulation, some lift. Any questions?

  15. We were in Shreveport for the March ‘record’ rainfall. Records are about record keeping not changes in climate. Growing up in the north, I will say these folks are better at handling water than ice. The ice storm the year before closed the interstate for a week.
    We had to go fetch family who were being evacuated in the middle of the night. It was a precaution. If the river had crested over the levee, the only way out would be by boat.
    The best I could tell this was the annual ‘record’ flood. It is a case of predicting which local area will need to be evacuated. Free sand bags at the following locations.
    Last year I bought $400 in gravel. I back the motorhome on to large boards. The soil is saturated all winter and after a good thunderstorm. MH is not a boat, sinks into mud.

  16. I don’t have the details available, but a September 1915 hurricane, preceded by one in August (busy year) that went through New Orleans was reported to have put 13 feet in western Lake Pontchartrain. A large shrimp catch was subsequently reported.
    If you look at the contours (or the lack thereof) of Ascension and southern Livingston Parish one is not encouraged to build there at ground(swamp) level. While still some distance west of the Lake, nevertheless a storm with an eye to the east (like Camille and Katrina) traps water in the lake and blows it west.

  17. FYI,
    East Baton Rouge Parish just released this interactive flood inundation map which shows the extent of the flooding, including every building affected.
    http://www.arcgis.com/home/webmap/viewer.html?webmap=cb332217bdab4572b4930e02d6655f84&extent=-91.4091,30.2533,-90.7149,30.765
    P.S. Many thanks for Anthony Watts breaking news about this major disaster back on August 13, when the only people who knew what was coming were informed Louisianians and Watts. The latest estimates I saw was that 100,000 buildings had flooded, nearly 300,000 people were personally affected, and nearly $22 billion in damages was caused.
    This is going to be a long recovery.
    https://youtu.be/TxWmrVbospE
    Finally, here is an amazing 56 hour loop of radar during just part of this historic storm.
    https://youtu.be/4p1l5Gq78bM

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