[fortysixdegrees]

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

[resolutebat]

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]

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]

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]

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]

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]

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]

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]

What? The storms in January and February were a huge deal for California coastal regions. The president visited Santa Cruz county afterwards.

[s1artibartfast]

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