No announcement yet.

California's ARkStorm Scenario Revisited & National Preparedness Month

  • Filter
  • Time
  • Show
Clear All
new posts

  • California's ARkStorm Scenario Revisited & National Preparedness Month

    California's ARkStorm Scenario Revisited & National Preparedness Month


    A little over 11 years ago, in ARkStorm: California’s other "Big One", we looked at a USGS Multi Hazards Demonstration Project (MHDP) analysis of a winter storm scenario called ARkStorm (for Atmospheric River 1,000) with historical precedence.

    From the USGS website:

    Experts have designed a large, scientifically realistic meteorological event followed by an examination of the secondary hazards (for example, landslides and flooding), physical damages to the built environment, and social and economic consequences. The hypothetical storm depicted here would strike the U.S. West Coast and be similar to the intense California winter storms of 1861 and 1862 that left the central valley of California impassible. The storm is estimated to produce precipitation that in many places exceeds levels only experienced on average once every 500 to 1,000 years.

    USGS Video On ARkStorm

    Like a great Los Angeles Earthquake (see Dr. Lucy Jones: `Imagine America Without Los Angeles’), a 9.0 quake on the Pacific Northwest's Cascadia fault (see FEMA: Cascadia Rising 2016), or a massive CME impact from the sun (see NASA: The Solar Super Storm Of 2012), ARkStorm falls into that category of rare - but over enough time, probably inevitable - disasters that would have national, and even global, impacts.

    Of course, we haven't taken a major hit from the sun since 1859 (i.e. the Carrington Event), the last really big quake on the San Andreas fault was in 1857, and the last great California flood was in 1861 and 1862, although there is geological evidence of this being a recurring event.

    And we have to go back even further - more than 300 years - for the last great Cascadia quake (and 210 years since the New Madrid series of quakes). Illustrating that just because something is inevitable, it doesn't necessarily mean in our lifetime.

    But just as another pandemic is inevitable, so to are these (and many other) disaster scenarios.

    While it doesn't get as much attention - at least outside of California - as the San Andreas fault, the ARkStorm scenario gets revived in the press every few years when new papers are published (see USGS ARkStorm Search Page) or updated.

    Although California's biggest concerns right now are drought and wildfires, a new study suggests that the climate grows hotter and dryer, it increases the odds of seeing another catastrophic ARkStorm event. You'll find a link, and the abstract below (follow the link to read it in its entirety), and a press release.

    Despite the recent prevalence of severe drought, California faces a broadly underappreciated risk of severe floods. Here, we investigate the physical characteristics of “plausible worst case scenario” extreme storm sequences capable of giving rise to “megaflood” conditions using a combination of climate model data and high-resolution weather modeling. Using the data from the Community Earth System Model Large Ensemble, we find that climate change has already doubled the likelihood of an event capable of producing catastrophic flooding, but larger future increases are likely due to continued warming. We further find that runoff in the future extreme storm scenario is 200 to 400% greater than historical values in the Sierra Nevada because of increased precipitation rates and decreased snow fraction. These findings have direct implications for flood and emergency management, as well as broader implications for hazard mitigation and climate adaptation activities.

    (Continue . . . )

    And from the UCLA Newsroom:

    Climate change makes catastrophic flood twice as likely, study shows

    Increased runoff could lead to devastating landslides and debris flows — particularly in hilly areas burned by wildfires

    David Colgan | August 12, 2022

    Key takeaways:
    • Climate change has already made extreme precipitation in California twice as likely, part of a trend projected to continue through 2100.
    • Extreme storm sequences are projected to generate 200% to 400% more runoff by the end of the century.
    Today’s study is the first part of ArkStorm 2.0, a scenario to prepare for catastrophic flooding in the western United States.

    California lives with a sleeping giant — an occasional flood so large that it inundates major valleys with water flows hundreds of miles long and tens of miles across.

    Motivated by one such flood that occurred in 1862, scientists investigated the phenomenon in 2010. They called it the “ArkStorm scenario,” reflecting the potential for an event of biblical proportions.

    To account for the additional flood-worsening effects of climate change, scientists from UCLA and the National Center for Atmospheric Research have completed the first part of ArkStorm 2.0.

    “In the future scenario, the storm sequence is bigger in almost every respect,” said Daniel Swain, UCLA climate scientist and co-author of the paper, which is published today in the journal Science Advances. “There’s more rain overall, more intense rainfall on an hourly basis and stronger wind.”

    In total, the research projects that end-of-the-century storms will generate 200% to 400% more runoff in the Sierra Nevada Mountains due to increased precipitation and more precipitation falling as rain, not snow.

    (Continue . . . .)

    Geological evidence suggests that as many as 9 other `Megafloods' have hit California over the past 2,000 years, suggesting these events recur every 200 years or so (range 51 to 426 years). It's pretty safe to assume if it has happened that many times before, it can happen again.

    But the difference is, today there are tens of millions of people living in harm's way.

    While we may not be able to prevent the next great natural disaster, we can take steps to prepare for it. California could improve its drainage system, shore up its dams and levees, and improve its ability to respond to a flooding emergency.

    But when tens of millions of people are affected, it will require a high degree of community, and individual, preparedness as well.

    This September - as I do every year - I'll devote a good deal of this blog to National Preparedness Month. I'll have new preparedness essays, and updated blogs from the past, all devoted to helping you become better prepared for whatever comes.

    According to FEMA's 2021 Household Survey on Preparedness, only 59% of households took 3 or more (of 12 recommended) preparedness steps in 2021.

    Although that is up 2% from the 2019 survey, it is far from ideal. Whether it is an ARkStorm Event, a CAT 5 Hurricane, a major earthquake, a solar storm, or a blizzard, you and your family may be called upon to fend for yourselves - without power, water, or emergency services - for days, or even weeks.

    So . . if a disaster struck your region today, and the power went out, stores closed their doors, and water stopped flowing from your kitchen tap for the next 7 to 14 days . . . you are you prepared with:
    • A battery operated NWS Emergency Radio to find out what was going on, and to get vital instructions from emergency officials
    • A decent first-aid kit, so that you can treat injuries
    • Enough non-perishable food and water on hand to feed and hydrate your family (including pets) for the duration
    • A way to provide light when the grid is down.
    • A way to cook safely without electricity
    • A way to purify or filter water
    • A way to handle basic sanitationand waste disposal.
    • A way to stay cool (fans) or warm when the power is out.
    • A small supply of cash to use in case credit/debit machines are not working
    • An emergency plan, including meeting places, emergency out-of-state contact numbers, a disaster buddy, and in case you must evacuate, a bug-out bag
    • Spare supply of essential prescription medicines that you or your family may need
    • A way to entertain yourself, or your kids, during a prolonged blackout

    If not, you've got some important work to do. A good place to get started is by visiting

    While preparedness may seem like a lot of work, it really isn’t.
    You don’t need an underground bunker, an armory, or 2 years worth of dehydrated food. But you do need the basics to carry on for a week or two, and a workable family (or business) emergency/disaster plan.

    For more information on how to prepare, I would invite you to visit:

    All medical discussions are for educational purposes. I am not a doctor, just a retired paramedic. Nothing I post should be construed as specific medical advice. If you have a medical problem, see your physician.