5 ms·

I posted this in a comment but going to post it again at the top level. For anyone interested in discussing this, I highly recommend you read the NHC forecaster

I posted this in a comment but going to post it again at the top level. For anyone interested in discussing this, I highly recommend you read the NHC forecasters day 2 summary. Ignore the media, just go straight to the source. This is very much unprecedented, despite many here posting that hurricane remnants hit CA all the time. https://www.wpc.ncep.noaa.gov/qpf/ero.php?opt=curr&day=2 https://www.wpc.ncep.noaa.gov/qpf/ero.php?opt=curr&day=2

resolutebat 3y ago
Here's the bit, buried towards the end: The 19/12z NAEFS is indicating IVT values 19.1 sigmas above the mean; it should be noted that it is using a dataset that does not include the rash of tropical cyclones that impacted the Southwest in the 1970's, so this value is likely a bit too high. Even assuming a non-standard distribution and standard deviations half as large, this is extreme. There is a very real potential for 3" amounts in an hour in this environment should sufficient instability be present. Even if instability was completely eroded, 0.5" an hour totals would be possible; heavy rain appears inevitable. The 00z Canadian Regional shows local amounts of towards 10", which would be exceeding rare for the region from a tropical cyclone, potentially unique for Nevada. The 100 year ARI is forecast to be exceeded. Some locations within this arid region are slated to get 1-2 years worth of rain in one day. If a 7"+ maximum materialized over Mount Charleston Sunday into early Monday, it would challenge Nevada's 24 hour rainfall record, set in 2004.
- pard68 3y ago
  What's wild to me is that 1-3" of rain / hour is about our norm for any given storm (southern MO, where evey cloud is a microburst). Really helps put into perspective how little rain Cali is used to.
  - dpe82 3y ago
    At least that part of California. It's a gigantic state and some areas see fairly significant seasonal rain. This storm, however, will impact a region that includes the Mojave Desert - the dryest place in North America.
    - anon84873628 3y ago
      IIRC, The excellent book Dreamt Land says 2/3 of California's precipitation falls in the northern 1/3 of the state. But it's the southern part with the ideal climate for agriculture. Hence the largest water movement system in history.
- luma 3y ago
  One interesting thing I learned while in Las Vegas during a major rain storm, a lot of the buildings leak like a sieve. Word was that heavy rain happens so rarely that leaks are rare to present themselves and thus hard to discover and hard to troubleshoot.
  - jstarfish 3y ago
    Same with your windshield wipers. You use them so infrequently, you don't notice the rubber disintegrated until the next time you need them.
s1artibartfast 3y ago
I'm watching this storm with interest, but I'm a little bit skeptical due to all the extreme language that the NWS forecast used around the storm in January February of this year, which ended up being basically a nothing Burger.
- anon84873628 3y ago
  What? The storms in January and February were a huge deal for California coastal regions. The president visited Santa Cruz county afterwards.
  - s1artibartfast 3y ago
    It depends on which ones you're talking about. I got hit pretty hard by the rain around New Years in late December and early January, so I was watching the forecasts fairly closely. There's also the question of what constitutes a huge deal. It was the later storms where the NWS is using far more extreme language that ended up being basically inconsequential
deleted 3y ago
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resolutebat 3y ago

Here's the bit, buried towards the end: The 19/12z NAEFS is indicating IVT values 19.1 sigmas above the mean; it should be noted that it is using a dataset that does not include the rash of tropical cyclones that impacted the Southwest in the 1970's, so this value is likely a bit too high. Even assuming a non-standard distribution and standard deviations half as large, this is extreme. There is a very real potential for 3" amounts in an hour in this environment should sufficient instability be present. Even if instability was completely eroded, 0.5" an hour totals would be possible; heavy rain appears inevitable. The 00z Canadian Regional shows local amounts of towards 10", which would be exceeding rare for the region from a tropical cyclone, potentially unique for Nevada. The 100 year ARI is forecast to be exceeded. Some locations within this arid region are slated to get 1-2 years worth of rain in one day. If a 7"+ maximum materialized over Mount Charleston Sunday into early Monday, it would challenge Nevada's 24 hour rainfall record, set in 2004.

pard68 3y ago
What's wild to me is that 1-3" of rain / hour is about our norm for any given storm (southern MO, where evey cloud is a microburst). Really helps put into perspective how little rain Cali is used to.
- dpe82 3y ago
  At least that part of California. It's a gigantic state and some areas see fairly significant seasonal rain. This storm, however, will impact a region that includes the Mojave Desert - the dryest place in North America.
  - anon84873628 3y ago
    IIRC, The excellent book Dreamt Land says 2/3 of California's precipitation falls in the northern 1/3 of the state. But it's the southern part with the ideal climate for agriculture. Hence the largest water movement system in history.
luma 3y ago
One interesting thing I learned while in Las Vegas during a major rain storm, a lot of the buildings leak like a sieve. Word was that heavy rain happens so rarely that leaks are rare to present themselves and thus hard to discover and hard to troubleshoot.
- jstarfish 3y ago
  Same with your windshield wipers. You use them so infrequently, you don't notice the rubber disintegrated until the next time you need them.

s1artibartfast 3y ago

I'm watching this storm with interest, but I'm a little bit skeptical due to all the extreme language that the NWS forecast used around the storm in January February of this year, which ended up being basically a nothing Burger.

anon84873628 3y ago
What? The storms in January and February were a huge deal for California coastal regions. The president visited Santa Cruz county afterwards.
- s1artibartfast 3y ago
  It depends on which ones you're talking about. I got hit pretty hard by the rain around New Years in late December and early January, so I was watching the forecasts fairly closely. There's also the question of what constitutes a huge deal. It was the later storms where the NWS is using far more extreme language that ended up being basically inconsequential

deleted 3y ago

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