28 votes

Hurricane Hilary is expected to bring significant flooding to Baja California, southern California, and the southwest US

Posted by spit-evil-olive-tips
Tags: weather, disasters.natural, hurricanes.hilary, mexico, usa, flooding, source.wikipedia, long read
https://en.wikipedia.org/wiki/2023_Pacific_hurricane_season#Hurricane_Hilary

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Title
2023 Pacific hurricane season - Wikipedia
Published
Aug 18 2023
Word count
3366 words

13 comments

  1. [7]
    spit-evil-olive-tips
    Link
    forecast discussion from the National Hurricane Center the NHC also publishes very useful maps and graphics, for example a map of rainfall potential and flash flooding likelihood from CNN's...

    forecast discussion from the National Hurricane Center

    1. Heavy rainfall associated with Hilary may produce areas of flash flooding and result in landslides over portions of Baja California Peninsula from late Friday into late Sunday. Rainfall impacts from Hilary within the Southwestern United States are expected to peak this weekend into Monday. Flash, urban, and arroyo flooding is possible with the potential for significant impacts.

    2. The threat of hurricane-force wind impacts is increasing along the west-central coast of the Baja California Peninsula and hurricane watches could be issued for a portion of that area tonight. Tropical storm conditions are expected to spread across the southern portion of the Baja California Peninsula by late Friday where a Tropical Storm Warning is in effect.

    3. The threat of significant wind impacts continues to increase for the northern portions of the Baja California Peninsula and the Southwestern United States, especially in areas of mountainous terrain. Although it is too soon to determine the location and magnitude of these impacts, interests in these areas should monitor the progress of Hilary and updates to the forecast. Watches could be issued for portions of this area on Friday.

    4. Large swells from Hilary will spread northward along the coast of southwestern Mexico and the Baja California Peninsula. These swells will reach the Gulf of California and northern portions of the Baja California Peninsula later this weekend.

    the NHC also publishes very useful maps and graphics, for example a map of rainfall potential and flash flooding likelihood

    from CNN's coverage:

    Southern California could receive some of Hilary’s heaviest rainfall. Widespread rainfall amounts of 2 to 4 inches may fall there and in southern Nevada from Saturday through Monday. The heaviest rainfall is expected mainly Sunday and Monday. Locally higher amounts up to 6 inches are possible in areas impacted by the heaviest deluges.

    Rainfall amounts of 1 to 2 inches are possible for parts of Arizona, Central California and northern Nevada.

    Multiple days of heavy rainfall will give the ground little opportunity to absorb moisture and can progressively worsen the flood threat.

    Daniel Swain, a climate scientist at the University of California at Los Angeles, said Wednesday that “multiple years’ worth of precipitation” could potentially fall in some of California’s driest areas.

    One of those places is Death Valley, California, the hottest place on Earth. Death Valley typically receives about 2 inches of rain across an entire year, according to NWS data. Moisture from Hilary could unleash enough rain to give Death Valley at least a year’s worth of rainfall in a single day.

    Rainfall this exceptional proved destructive in Death Valley last year. Around 1,000 people became stranded in Death Valley National Park last August when 1.46 inches of rain fell in 24 hours and unleashed flash flooding that washed away roads and entombed cars in floodwater-swept debris.

    I'm sure there are Tilderinos who live in the projected path of this - how's it going? what (if anything) are you doing to prepare? what's the mood like in your neighborhood/town/city?

    13 votes
    1. [4]
      domukin
      Link Parent
      Southern California here… I just heard about it today and feel like we are going to get caught with our pants down. It’s incredibly hard to gauge the risk. On one hand there apparently hasn’t been...

      Southern California here… I just heard about it today and feel like we are going to get caught with our pants down. It’s incredibly hard to gauge the risk. On one hand there apparently hasn’t been a hurricane here in 60+ years (since they started naming storms). But because of that, we don’t really have a culture of preparing for such an event. I may go get some sand bags.

      15 votes
      1. [3]
        Bohmbot
        Link Parent
        Also from So Cal (about 35 miles east of Los Angeles). Also just reading about it for the first time. My hunch is that most folks in my area assume it will not be a big deal or won't hit us as we...

        Also from So Cal (about 35 miles east of Los Angeles). Also just reading about it for the first time. My hunch is that most folks in my area assume it will not be a big deal or won't hit us as we are more inland.

        Aside from the potential rains and flooding, it's the winds that I fear the most for the greater LA area.

        8 votes
        1. [2]
          Thoughtninja
          Link Parent
          Being from the other La (Louisiana) wind damage is the most likely issue with this. Meaning power and travel are going to be affected post storm. Well during too. Fill your bathtub if you have one...

          Being from the other La (Louisiana) wind damage is the most likely issue with this. Meaning power and travel are going to be affected post storm. Well during too. Fill your bathtub if you have one (flushing toilets/basic washing). Probably too late to stock up on non perishable foods or water. If you have any containers you can fill with tap water I'd recommend it. Even if you end up not really affected it never hurts to be prepared even in the most basic ways.

          5 votes
          1. spit-evil-olive-tips
            Link Parent
            wind damage is absolutely a concern, but flooding will be a huge problem as well. somewhat counter-intuitively, flooding tends to be worse in the desert than somewhere swampy like Louisiana, for a...

            wind damage is absolutely a concern, but flooding will be a huge problem as well.

            somewhat counter-intuitively, flooding tends to be worse in the desert than somewhere swampy like Louisiana, for a variety of reasons:

            In deserts, flash floods can be particularly deadly for several reasons. First, storms in arid regions are infrequent, but they can deliver an enormous amount of water in a very short time. Second, these rains often fall on poorly absorbent and often clay-like soil, which greatly increases the amount of runoff that rivers and other water channels have to handle. These regions tend not to have the infrastructure that wetter regions have to divert water from structures and roads, such as storm drains, culverts, and retention basins, either because of sparse population or poverty, or because residents believe the risk of flash floods is not high enough to justify the expense. In fact, in some areas, desert roads frequently cross a dry river and creek beds without bridges. From the driver's perspective, there may be clear weather, when a river unexpectedly forms ahead of or around the vehicle in a matter of seconds. Finally, the lack of regular rain to clear water channels may cause flash floods in deserts to be headed by large amounts of debris, such as rocks, branches, and logs.

            there's also significant differences in infrastructure and the built environment. somewhere like Louisiana, you're not going to have as many basements or underground tunnels as you will in a desert climate. in the Southwest, flooding is expected to be rare, the water table is low, and the soil is generally pretty stable to dig into.

            an estimated 2000 homeless people live in tunnels under Las Vegas, for example. and hotels and casinos in Vegas probably have most of their power & telecoms infrastructure below ground level. probably their vaults for handling cash, as well.

            4 votes
    2. knocklessmonster
      (edited )
      Link Parent
      I'm in Orange County, ~250mi north of the border. Any weather should land Saturday. I'd be surprised if anything major came of it. We deal with desert monsoons, even out west on the coastal...

      I'm in Orange County, ~250mi north of the border. Any weather should land Saturday.

      I'd be surprised if anything major came of it. We deal with desert monsoons, even out west on the coastal floodplain, that peter over the mountains and generally die to our climate. Every so often we get sensationalist forecasts of this or that hurricane bringing a bunch of rain but it never quite materializes this far north, even being geographically coastal (it's 15 miles southwest of me).

      I don't think it's going to hit in a huge way. There are four things: the land massses of Baja and Mexico, wind currents, oceanic currents, and the resulting water temperatures from these currents, which flow south from the Arctic.

      We're used to some pretty intense winds at the 60-80mph range for the worst of Santa Anas, and should be able to weather what will most likely be weakened hurricane winds. If we get solid storms many areas around me will definitely flood, but I wouldn't expect worse than a good El Nino year (which is pretty bad, but not Florida in a hurricane). My area of my city drains quite well, so I'm not worried, but other areas, especially up towards LA county and the smaller cities, can flood quite bad.

      5 votes
    3. clubizarre
      Link Parent
      Southern CA here, closer to San Diego. I've been getting a lot of emails from the power and Internet companies giving tips and possible outages. But other than that, I've moved all patio furniture...

      Southern CA here, closer to San Diego. I've been getting a lot of emails from the power and Internet companies giving tips and possible outages. But other than that, I've moved all patio furniture into the garage which is about all I can really do. But usually with weather reports, stuff gets hyped up with STORM WATCH 2023!!!!1 and then it stays over the ocean.

      And I'm not diminishing the threat at all. Just cautiously watching as the storm gets closer.

      2 votes
  3. [5]
    pedantzilla
    Link
    I thought "hurricanes" in the Pacific were called typhoons?

    I thought "hurricanes" in the Pacific were called typhoons?

    2 votes
    1. [4]
      symmetry
      (edited )
      Link Parent
      Typhoons in the Northwestern side (Asia). Hurricanes in the Northeastern (North America). Edit: wrong direction as pointed out

      Typhoons in the Northwestern side (Asia). Hurricanes in the Northeastern (North America).

      Edit: wrong direction as pointed out

      11 votes
      2. [2]
        EmperorPenguin
        Link Parent
        Is there any reason for this completely arbitrary naming for the same thing?

        Is there any reason for this completely arbitrary naming for the same thing?

        1 vote
        1. nukeman
          Link Parent
          Language. Hurricane comes from the Spanish huracán, typhoon is either Chinese or Arabic-Hindustani, and cyclone was coined by a British sailor who settled in India.

          Language. Hurricane comes from the Spanish huracán, typhoon is either Chinese or Arabic-Hindustani, and cyclone was coined by a British sailor who settled in India.

          12 votes